TY  - JOUR
AU  - Tomić, Aleksandra
AU  - Pomeroy, Brett
AU  - Todić, Branislav
AU  - Likozar, Blaž
AU  - Nikačević, Nikola
PY  - 2024-07
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7452
AB  - The implementation of the liquid organic hydrogen carrier (LOHC) technology for efficient energy storage requires the development of a reliable kinetic model for both hydrogenation and dehydrogenation processes. In this research study, the catalytic hydrocarbon saturation for a dibenzyltoluene (DBT) mixture solution, containing dibenzylbenzene (DBB), dibenzylethylbenzene (DBEB) and impurities has been performed in the presence of Ru/Al2O3 particles. The influence of different reaction conditions, such as temperature, pressure, initial reactant concentration, catalyst amount and stirring speed has been examined. A measurement-based system micro-kinetics, based on the Langmuir–Hinshelwood mechanism with dissociative H2 surface adsorption, has been derived. H2 thermodynamic solubility equilibrium was defined through Henry's law. The adsorbing, desorption and reactivity of inert solvent molecules was not considered to be relevant. The mass transfer resistance over 1000 rpm stirring speed was negligible. Relative- and mean squared error of representation were 40.9% and 1.00×10−4, respectively. Expressions gave an excellent data prediction for the profile period trends with a relatively accurate estimation of H2 intermediates' rate selectivity, H2-covered area approximation and pathway rate-determining steps. Due to the lack of commercially available standard chemical compounds for quantitative analysis techniques, a novel experiment-based numerical calibration method was developed. Mean field (micro)kinetics represent an advancement in the mesoscale mechanistic understanding of physical interface phenomena. This also enables catalysis structure–activity relationships, unlocking the methodology for new LOHC reaching beyond traditional, such as ammonia, methanol and formate, which do not release H2 alone. Integrated multiscale simulations could include fluidics later on.
PB  - Elsevier Ltd.
T2  - Applied Energy
T1  - Catalytic hydrogenation reaction micro-kinetic model for dibenzyltoluene as liquid organic hydrogen carrier
SP  - 123262
VL  - 365
DO  - 10.1016/j.apenergy.2024.123262
ER  - 

@article{
author = "Tomić, Aleksandra and Pomeroy, Brett and Todić, Branislav and Likozar, Blaž and Nikačević, Nikola",
year = "2024-07",
abstract = "The implementation of the liquid organic hydrogen carrier (LOHC) technology for efficient energy storage requires the development of a reliable kinetic model for both hydrogenation and dehydrogenation processes. In this research study, the catalytic hydrocarbon saturation for a dibenzyltoluene (DBT) mixture solution, containing dibenzylbenzene (DBB), dibenzylethylbenzene (DBEB) and impurities has been performed in the presence of Ru/Al2O3 particles. The influence of different reaction conditions, such as temperature, pressure, initial reactant concentration, catalyst amount and stirring speed has been examined. A measurement-based system micro-kinetics, based on the Langmuir–Hinshelwood mechanism with dissociative H2 surface adsorption, has been derived. H2 thermodynamic solubility equilibrium was defined through Henry's law. The adsorbing, desorption and reactivity of inert solvent molecules was not considered to be relevant. The mass transfer resistance over 1000 rpm stirring speed was negligible. Relative- and mean squared error of representation were 40.9% and 1.00×10−4, respectively. Expressions gave an excellent data prediction for the profile period trends with a relatively accurate estimation of H2 intermediates' rate selectivity, H2-covered area approximation and pathway rate-determining steps. Due to the lack of commercially available standard chemical compounds for quantitative analysis techniques, a novel experiment-based numerical calibration method was developed. Mean field (micro)kinetics represent an advancement in the mesoscale mechanistic understanding of physical interface phenomena. This also enables catalysis structure–activity relationships, unlocking the methodology for new LOHC reaching beyond traditional, such as ammonia, methanol and formate, which do not release H2 alone. Integrated multiscale simulations could include fluidics later on.",
publisher = "Elsevier Ltd.",
journal = "Applied Energy",
title = "Catalytic hydrogenation reaction micro-kinetic model for dibenzyltoluene as liquid organic hydrogen carrier",
pages = "123262",
volume = "365",
doi = "10.1016/j.apenergy.2024.123262"
}

Tomić, A., Pomeroy, B., Todić, B., Likozar, B.,& Nikačević, N.. (2024-07). Catalytic hydrogenation reaction micro-kinetic model for dibenzyltoluene as liquid organic hydrogen carrier. in Applied Energy
Elsevier Ltd.., 365, 123262.
https://doi.org/10.1016/j.apenergy.2024.123262

Tomić A, Pomeroy B, Todić B, Likozar B, Nikačević N. Catalytic hydrogenation reaction micro-kinetic model for dibenzyltoluene as liquid organic hydrogen carrier. in Applied Energy. 2024;365:123262.
doi:10.1016/j.apenergy.2024.123262 .

Tomić, Aleksandra, Pomeroy, Brett, Todić, Branislav, Likozar, Blaž, Nikačević, Nikola, "Catalytic hydrogenation reaction micro-kinetic model for dibenzyltoluene as liquid organic hydrogen carrier" in Applied Energy, 365 (2024-07):123262,
https://doi.org/10.1016/j.apenergy.2024.123262 . .

TY  - JOUR
AU  - Pravilović, Radoslava
AU  - Janković, Tamara
AU  - Veljković, Milica
AU  - Todić, Branislav
AU  - Simović, Milica
AU  - Bezbradica, Dejan
AU  - Nikačević, Nikola
PY  - 2023
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/6385
AB  - A new micro-kinetic model of the enzyme-catalyzed synthesis of fructo-oligosaccharides (FOS) was developed. A commercial enzyme mixture Pectinex® Ultra SP-L derived from Aspergillus aculeatus was used. A variety of initial enzyme concentrations (1–5 vol%) and sucrose concentrations (400–600 g/L) were experimentally investigated and included in kinetic modeling. Several variations of kinetic mechanisms and corresponding models have been examined. A hybrid genetic algorithm was used to predict the kinetic parameters simultaneously for all experimental data. The best fitting model has been adopted, and with an average error of 13.34%, it describes the experimental data very well. The influence of initial concentrations on the conversion of sucrose and production of FOS is being carefully investigated. It was shown that the initial sucrose concentration significantly affects the highest level of FOS concentration, but the enzyme concentration controls the time at which maximum is reached as well as the rate of FOS decomposition.
PB  - John Wiley and Sons Inc.
T2  - AIChE Journal
T1  - Micro-kinetic model of fructo-oligosaccharide synthesis for prebiotic products
IS  - 9
SP  - e18122
VL  - 69
DO  - 10.1002/aic.18122
ER  - 

@article{
author = "Pravilović, Radoslava and Janković, Tamara and Veljković, Milica and Todić, Branislav and Simović, Milica and Bezbradica, Dejan and Nikačević, Nikola",
year = "2023",
abstract = "A new micro-kinetic model of the enzyme-catalyzed synthesis of fructo-oligosaccharides (FOS) was developed. A commercial enzyme mixture Pectinex® Ultra SP-L derived from Aspergillus aculeatus was used. A variety of initial enzyme concentrations (1–5 vol%) and sucrose concentrations (400–600 g/L) were experimentally investigated and included in kinetic modeling. Several variations of kinetic mechanisms and corresponding models have been examined. A hybrid genetic algorithm was used to predict the kinetic parameters simultaneously for all experimental data. The best fitting model has been adopted, and with an average error of 13.34%, it describes the experimental data very well. The influence of initial concentrations on the conversion of sucrose and production of FOS is being carefully investigated. It was shown that the initial sucrose concentration significantly affects the highest level of FOS concentration, but the enzyme concentration controls the time at which maximum is reached as well as the rate of FOS decomposition.",
publisher = "John Wiley and Sons Inc.",
journal = "AIChE Journal",
title = "Micro-kinetic model of fructo-oligosaccharide synthesis for prebiotic products",
number = "9",
pages = "e18122",
volume = "69",
doi = "10.1002/aic.18122"
}

Pravilović, R., Janković, T., Veljković, M., Todić, B., Simović, M., Bezbradica, D.,& Nikačević, N.. (2023). Micro-kinetic model of fructo-oligosaccharide synthesis for prebiotic products. in AIChE Journal
John Wiley and Sons Inc.., 69(9), e18122.
https://doi.org/10.1002/aic.18122

Pravilović R, Janković T, Veljković M, Todić B, Simović M, Bezbradica D, Nikačević N. Micro-kinetic model of fructo-oligosaccharide synthesis for prebiotic products. in AIChE Journal. 2023;69(9):e18122.
doi:10.1002/aic.18122 .

Pravilović, Radoslava, Janković, Tamara, Veljković, Milica, Todić, Branislav, Simović, Milica, Bezbradica, Dejan, Nikačević, Nikola, "Micro-kinetic model of fructo-oligosaccharide synthesis for prebiotic products" in AIChE Journal, 69, no. 9 (2023):e18122,
https://doi.org/10.1002/aic.18122 . .

TY  - JOUR
AU  - Pravilović, Radoslava
AU  - Todić, Branislav
AU  - Simović, Milica
AU  - Banjanac, Katarina
AU  - Bezbradica, Dejan
AU  - Nikačević, Nikola
PY  - 2022
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5226
AB  - A new micro-kinetic model is proposed for galacto-oligosaccharide (GOS) synthesis with β-galactosidase from Aspergillus oryzae. Several kinetic models with similar reaction mechanisms, i.e., steps and kinetic constants, have been investigated covering a range of initial lactose (20-40 wt %) and enzyme concentrations (0.5-2 mg/mL). The kinetic parameters were estimated simultaneously for all experimental results using a hybrid genetic algorithm. A detailed analysis of the effect of process parameters on the concentrations of lactose and GOS is performed. The proposed model has a very good quantitative fit of the experimental data, with an average error of 9.34%. More importantly, qualitative trends for the change in the concentration of lactose and GOS are predicted excellently, especially if one takes into account the variation of both concentrations of enzyme and lactose in a range wider than reported in the literature to date. Also, the analysis between the two comparative reactions of transglycosylation and lactose hydrolysis confirmed the positive effect of increasing lactose concentration on the production of GOS. On the other hand, a higher enzyme concentration resulted in a faster production of GOS but with more intensive decomposition at longer reaction times.
PB  - American Chemical Society
T2  - Industrial and Engineering Chemistry Research
T1  - Kinetic Model for Galacto-Oligosaccharide Synthesis
EP  - 14198
IS  - 38
SP  - 14189
VL  - 61
DO  - 10.1021/acs.iecr.2c02053
ER  - 

@article{
author = "Pravilović, Radoslava and Todić, Branislav and Simović, Milica and Banjanac, Katarina and Bezbradica, Dejan and Nikačević, Nikola",
year = "2022",
abstract = "A new micro-kinetic model is proposed for galacto-oligosaccharide (GOS) synthesis with β-galactosidase from Aspergillus oryzae. Several kinetic models with similar reaction mechanisms, i.e., steps and kinetic constants, have been investigated covering a range of initial lactose (20-40 wt %) and enzyme concentrations (0.5-2 mg/mL). The kinetic parameters were estimated simultaneously for all experimental results using a hybrid genetic algorithm. A detailed analysis of the effect of process parameters on the concentrations of lactose and GOS is performed. The proposed model has a very good quantitative fit of the experimental data, with an average error of 9.34%. More importantly, qualitative trends for the change in the concentration of lactose and GOS are predicted excellently, especially if one takes into account the variation of both concentrations of enzyme and lactose in a range wider than reported in the literature to date. Also, the analysis between the two comparative reactions of transglycosylation and lactose hydrolysis confirmed the positive effect of increasing lactose concentration on the production of GOS. On the other hand, a higher enzyme concentration resulted in a faster production of GOS but with more intensive decomposition at longer reaction times.",
publisher = "American Chemical Society",
journal = "Industrial and Engineering Chemistry Research",
title = "Kinetic Model for Galacto-Oligosaccharide Synthesis",
pages = "14198-14189",
number = "38",
volume = "61",
doi = "10.1021/acs.iecr.2c02053"
}

Pravilović, R., Todić, B., Simović, M., Banjanac, K., Bezbradica, D.,& Nikačević, N.. (2022). Kinetic Model for Galacto-Oligosaccharide Synthesis. in Industrial and Engineering Chemistry Research
American Chemical Society., 61(38), 14189-14198.
https://doi.org/10.1021/acs.iecr.2c02053

Pravilović R, Todić B, Simović M, Banjanac K, Bezbradica D, Nikačević N. Kinetic Model for Galacto-Oligosaccharide Synthesis. in Industrial and Engineering Chemistry Research. 2022;61(38):14189-14198.
doi:10.1021/acs.iecr.2c02053 .

Pravilović, Radoslava, Todić, Branislav, Simović, Milica, Banjanac, Katarina, Bezbradica, Dejan, Nikačević, Nikola, "Kinetic Model for Galacto-Oligosaccharide Synthesis" in Industrial and Engineering Chemistry Research, 61, no. 38 (2022):14189-14198,
https://doi.org/10.1021/acs.iecr.2c02053 . .

TY  - JOUR
AU  - Bukur, Dragomir B.
AU  - Mandić, Miloš
AU  - Todić, Branislav
AU  - Nikačević, Nikola
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4452
AB  - In this study we investigate performance characteristics (catalyst effectiveness, CH4 selectivity, and hydrocarbon product distribution) of with a highly active Co/Re/Al(2)O(3 )catalyst particle for Fischer-Tropsch synthesis. In numerical simulations we utilize kinetic parameters for CO consumption rate, CH4 formation rate and hydrocarbon formation rates (C-2+ hydrocarbons) determined from experiments with this catalyst to study effects of catalyst activity, catalyst particle shape (sphere, slab, solid and hollow cylinder), size (i.e. diffusion length), catalyst distribution (uniform vs. eggshell type distribution for a spherical particle) and process conditions (temperature, pressure, syngas composition and conversion level) on the catalyst performance. With increase in Thiele modulus (i.e. particle size at a fixed set of process conditions) we observe increasing H-2/CO ratio profile towards the center of the particle resulting in increase of local and average CH4 selectivity. The goal is to find conditions which allow one to use sufficiently large particles to reduce pressure drop, while avoiding negative influence of diffusional limitations on selectivity and activity. For each catalyst particle shape we determined values of Thiele modulus, i.e. characteristic length of diffusion, corresponding to the upper limit of the kinetic region, and investigated how it changes with operating conditions. We found that simultaneous increase of pressure and the use of syngas with H-2/CO feed ratio of 1.4-1.7 is the best strategy for mitigating the negative impact of intraparticle diffusional limitations on CH4 selectivity. For a spherical particle of 1 mm in diameter, one can achieve CH4 selectivity of 5.6% with catalyst effectiveness factor of 1.07 at the reactor inlet by operating at 50 bar, 473 K and H-2/CO = 1.4.
PB  - Elsevier, Amsterdam
T2  - Catalysis Today
T1  - Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst
EP  - 155
SP  - 146
VL  - 343
DO  - 10.1016/j.cattod.2018.10.069
ER  - 

@article{
author = "Bukur, Dragomir B. and Mandić, Miloš and Todić, Branislav and Nikačević, Nikola",
year = "2020",
abstract = "In this study we investigate performance characteristics (catalyst effectiveness, CH4 selectivity, and hydrocarbon product distribution) of with a highly active Co/Re/Al(2)O(3 )catalyst particle for Fischer-Tropsch synthesis. In numerical simulations we utilize kinetic parameters for CO consumption rate, CH4 formation rate and hydrocarbon formation rates (C-2+ hydrocarbons) determined from experiments with this catalyst to study effects of catalyst activity, catalyst particle shape (sphere, slab, solid and hollow cylinder), size (i.e. diffusion length), catalyst distribution (uniform vs. eggshell type distribution for a spherical particle) and process conditions (temperature, pressure, syngas composition and conversion level) on the catalyst performance. With increase in Thiele modulus (i.e. particle size at a fixed set of process conditions) we observe increasing H-2/CO ratio profile towards the center of the particle resulting in increase of local and average CH4 selectivity. The goal is to find conditions which allow one to use sufficiently large particles to reduce pressure drop, while avoiding negative influence of diffusional limitations on selectivity and activity. For each catalyst particle shape we determined values of Thiele modulus, i.e. characteristic length of diffusion, corresponding to the upper limit of the kinetic region, and investigated how it changes with operating conditions. We found that simultaneous increase of pressure and the use of syngas with H-2/CO feed ratio of 1.4-1.7 is the best strategy for mitigating the negative impact of intraparticle diffusional limitations on CH4 selectivity. For a spherical particle of 1 mm in diameter, one can achieve CH4 selectivity of 5.6% with catalyst effectiveness factor of 1.07 at the reactor inlet by operating at 50 bar, 473 K and H-2/CO = 1.4.",
publisher = "Elsevier, Amsterdam",
journal = "Catalysis Today",
title = "Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst",
pages = "155-146",
volume = "343",
doi = "10.1016/j.cattod.2018.10.069"
}

Bukur, D. B., Mandić, M., Todić, B.,& Nikačević, N.. (2020). Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst. in Catalysis Today
Elsevier, Amsterdam., 343, 146-155.
https://doi.org/10.1016/j.cattod.2018.10.069

Bukur DB, Mandić M, Todić B, Nikačević N. Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst. in Catalysis Today. 2020;343:146-155.
doi:10.1016/j.cattod.2018.10.069 .

Bukur, Dragomir B., Mandić, Miloš, Todić, Branislav, Nikačević, Nikola, "Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst" in Catalysis Today, 343 (2020):146-155,
https://doi.org/10.1016/j.cattod.2018.10.069 . .

TY  - JOUR
AU  - Nikačević, Nikola
AU  - Todić, Branislav
AU  - Mandić, Miloš
AU  - Petkovska, Menka
AU  - Bukur, Dragomir B.
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4453
AB  - One-dimensional pseudo-homogenous dynamic reactor model, incorporating detailed Fischer-Tropsch kinetics, was applied in a theoretical analysis of forced periodic operations. A milli-scale fixed-bed reactor was analyzed, using design and operation parameters, obtained previously in a steady-state optimization. Dynamic optimization and NLP methods were utilized to obtain optimal values of amplitude(s), frequency and phase shift(s) of sine-wave variation of inputs, around the corresponding optimal steady-state values, which maximize the productivity of C5+ hydrocarbons. Inlet variables that were modulated are: coolant temperature, reactants molar ratio, mass flow rate and pressure. In addition to the single input forcing, simultaneous modulations of multiple inputs were also considered, with combinations of the listed inlet variables. Among the single input cases, periodic variation of the coolant temperature resulted in the highest relative improvement of C5+, productivity by 30%. Multiple inputs forcing showed additional potential for improvement, resulting in relative c(5+) productivity increase of 52% for synchronized modulation of the coolant temperature, reactants molar ratio and mass flow rate. However, the increase in C5+ productivity is accompanied with relative increase in methane selectivity of 22-33% (relative to the steady-state value). The results suggest that, in the case of multiple input variations with high amplitudes, modulation of the inlet reactants molar ratio mainly contributes to the increase of CO conversion (e.g. reaction rate), the coolant temperature forcing slightly increases selectivity towards the desirable higher hydrocarbons (C5+), while the variation of the inlet mass flow rate enables better reaction temperature control and prevents a thermal runway.
PB  - Elsevier, Amsterdam
T2  - Catalysis Today
T1  - Optimization of forced periodic operations in milli-scale fixed bed reactor for Fischer-Tropsch synthesis
EP  - 164
SP  - 156
VL  - 343
DO  - 10.1016/j.cattod.2018.12.032
ER  - 

@article{
author = "Nikačević, Nikola and Todić, Branislav and Mandić, Miloš and Petkovska, Menka and Bukur, Dragomir B.",
year = "2020",
abstract = "One-dimensional pseudo-homogenous dynamic reactor model, incorporating detailed Fischer-Tropsch kinetics, was applied in a theoretical analysis of forced periodic operations. A milli-scale fixed-bed reactor was analyzed, using design and operation parameters, obtained previously in a steady-state optimization. Dynamic optimization and NLP methods were utilized to obtain optimal values of amplitude(s), frequency and phase shift(s) of sine-wave variation of inputs, around the corresponding optimal steady-state values, which maximize the productivity of C5+ hydrocarbons. Inlet variables that were modulated are: coolant temperature, reactants molar ratio, mass flow rate and pressure. In addition to the single input forcing, simultaneous modulations of multiple inputs were also considered, with combinations of the listed inlet variables. Among the single input cases, periodic variation of the coolant temperature resulted in the highest relative improvement of C5+, productivity by 30%. Multiple inputs forcing showed additional potential for improvement, resulting in relative c(5+) productivity increase of 52% for synchronized modulation of the coolant temperature, reactants molar ratio and mass flow rate. However, the increase in C5+ productivity is accompanied with relative increase in methane selectivity of 22-33% (relative to the steady-state value). The results suggest that, in the case of multiple input variations with high amplitudes, modulation of the inlet reactants molar ratio mainly contributes to the increase of CO conversion (e.g. reaction rate), the coolant temperature forcing slightly increases selectivity towards the desirable higher hydrocarbons (C5+), while the variation of the inlet mass flow rate enables better reaction temperature control and prevents a thermal runway.",
publisher = "Elsevier, Amsterdam",
journal = "Catalysis Today",
title = "Optimization of forced periodic operations in milli-scale fixed bed reactor for Fischer-Tropsch synthesis",
pages = "164-156",
volume = "343",
doi = "10.1016/j.cattod.2018.12.032"
}

Nikačević, N., Todić, B., Mandić, M., Petkovska, M.,& Bukur, D. B.. (2020). Optimization of forced periodic operations in milli-scale fixed bed reactor for Fischer-Tropsch synthesis. in Catalysis Today
Elsevier, Amsterdam., 343, 156-164.
https://doi.org/10.1016/j.cattod.2018.12.032

Nikačević N, Todić B, Mandić M, Petkovska M, Bukur DB. Optimization of forced periodic operations in milli-scale fixed bed reactor for Fischer-Tropsch synthesis. in Catalysis Today. 2020;343:156-164.
doi:10.1016/j.cattod.2018.12.032 .

Nikačević, Nikola, Todić, Branislav, Mandić, Miloš, Petkovska, Menka, Bukur, Dragomir B., "Optimization of forced periodic operations in milli-scale fixed bed reactor for Fischer-Tropsch synthesis" in Catalysis Today, 343 (2020):156-164,
https://doi.org/10.1016/j.cattod.2018.12.032 . .

TY  - JOUR
AU  - Ma, Wenping
AU  - Jacobs, Gary
AU  - Sparks, Dennis E.
AU  - Todić, Branislav
AU  - Bukur, Dragomir B.
AU  - Davis, Burtron H.
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4484
AB  - Quantitative data comparing iron and cobalt based catalysts for the Fischer-Tropsch synthesis (FTS) are scarce due to the fact that these two kinds of catalysts typically utilize different process conditions. This paper focuses on studying the catalytic behavior of two highly active iron and cobalt based research catalysts at clean conditions and during poisoning with common syngas contaminants. The catalyst activity and selectivity at identical conditions, the CO conversion effect, and the effect of poisons on iron and cobalt catalysts were systematically explored in a quantitative manner. At a set of identical FTS conditions, the cobalt catalyst was 2.5 times as active as the iron catalyst with higher CH4 and C-5+ selectivities but much less olefins and lower CO2 selectivity. Cobalt based catalysts are more susceptible to deactivation by oxidation at high CO conversions (e.g.  gt  80%) due to the high partial pressure of water (P-H2O) in the reactor, while the iron catalyst can be stabilized at a high conversion level. Under clean FTS conditions, the cobalt catalysts displayed a more pronounced CO conversion effect on stability and selectivity; on the other hand, a combination of effects (i.e. from CO conversion and the nature of the catalyst) were observed for the iron catalysts. The sensitivities of the Fe and Co catalysts to the typical contaminants (i.e., H2S and NH3) present in the syngas derived from coal, natural gas or biomass were compared. Iron and cobalt catalysts exhibited similar resistance to the H2S poison (i.e. threshold levels 25-50 ppb), but the iron catalyst was found to be much more resistant to ammonia than the cobalt catalyst (i.e., threshold levels of 80 ppm and 45 ppb, respectively). Co-feeding 150-200 ppm ammonia lowered CH4 selectivity and 2-olefin content (suppressing secondary reactions of 1-olefin) on both types of catalysts. In contrast, co-feeding up to 1 ppm H2S significantly increased CH4 formation only on cobalt catalysts but had a minor effect on CH4 selectivity with iron catalysts. It increased 2-olefin content (enhanced secondary reactions of 1-olefin) regardless of catalyst type. H2S and NH3 have different impacts on H-2, CO adsorption, and the formation of sulfur and nitride compounds have been proposed to explain these dissimilar effects.
PB  - Elsevier, Amsterdam
T2  - Catalysis Today
T1  - Quantitative comparison of iron and cobalt based catalysts for the Fischer-Tropsch synthesis under clean and poisoning conditions
EP  - 136
SP  - 125
VL  - 343
DO  - 10.1016/j.cattod.2019.04.011
ER  - 

@article{
author = "Ma, Wenping and Jacobs, Gary and Sparks, Dennis E. and Todić, Branislav and Bukur, Dragomir B. and Davis, Burtron H.",
year = "2020",
abstract = "Quantitative data comparing iron and cobalt based catalysts for the Fischer-Tropsch synthesis (FTS) are scarce due to the fact that these two kinds of catalysts typically utilize different process conditions. This paper focuses on studying the catalytic behavior of two highly active iron and cobalt based research catalysts at clean conditions and during poisoning with common syngas contaminants. The catalyst activity and selectivity at identical conditions, the CO conversion effect, and the effect of poisons on iron and cobalt catalysts were systematically explored in a quantitative manner. At a set of identical FTS conditions, the cobalt catalyst was 2.5 times as active as the iron catalyst with higher CH4 and C-5+ selectivities but much less olefins and lower CO2 selectivity. Cobalt based catalysts are more susceptible to deactivation by oxidation at high CO conversions (e.g.  gt  80%) due to the high partial pressure of water (P-H2O) in the reactor, while the iron catalyst can be stabilized at a high conversion level. Under clean FTS conditions, the cobalt catalysts displayed a more pronounced CO conversion effect on stability and selectivity; on the other hand, a combination of effects (i.e. from CO conversion and the nature of the catalyst) were observed for the iron catalysts. The sensitivities of the Fe and Co catalysts to the typical contaminants (i.e., H2S and NH3) present in the syngas derived from coal, natural gas or biomass were compared. Iron and cobalt catalysts exhibited similar resistance to the H2S poison (i.e. threshold levels 25-50 ppb), but the iron catalyst was found to be much more resistant to ammonia than the cobalt catalyst (i.e., threshold levels of 80 ppm and 45 ppb, respectively). Co-feeding 150-200 ppm ammonia lowered CH4 selectivity and 2-olefin content (suppressing secondary reactions of 1-olefin) on both types of catalysts. In contrast, co-feeding up to 1 ppm H2S significantly increased CH4 formation only on cobalt catalysts but had a minor effect on CH4 selectivity with iron catalysts. It increased 2-olefin content (enhanced secondary reactions of 1-olefin) regardless of catalyst type. H2S and NH3 have different impacts on H-2, CO adsorption, and the formation of sulfur and nitride compounds have been proposed to explain these dissimilar effects.",
publisher = "Elsevier, Amsterdam",
journal = "Catalysis Today",
title = "Quantitative comparison of iron and cobalt based catalysts for the Fischer-Tropsch synthesis under clean and poisoning conditions",
pages = "136-125",
volume = "343",
doi = "10.1016/j.cattod.2019.04.011"
}

Ma, W., Jacobs, G., Sparks, D. E., Todić, B., Bukur, D. B.,& Davis, B. H.. (2020). Quantitative comparison of iron and cobalt based catalysts for the Fischer-Tropsch synthesis under clean and poisoning conditions. in Catalysis Today
Elsevier, Amsterdam., 343, 125-136.
https://doi.org/10.1016/j.cattod.2019.04.011

Ma W, Jacobs G, Sparks DE, Todić B, Bukur DB, Davis BH. Quantitative comparison of iron and cobalt based catalysts for the Fischer-Tropsch synthesis under clean and poisoning conditions. in Catalysis Today. 2020;343:125-136.
doi:10.1016/j.cattod.2019.04.011 .

Ma, Wenping, Jacobs, Gary, Sparks, Dennis E., Todić, Branislav, Bukur, Dragomir B., Davis, Burtron H., "Quantitative comparison of iron and cobalt based catalysts for the Fischer-Tropsch synthesis under clean and poisoning conditions" in Catalysis Today, 343 (2020):125-136,
https://doi.org/10.1016/j.cattod.2019.04.011 . .

TY  - JOUR
AU  - Kljajić, Nikola
AU  - Todić, Branislav
AU  - Slavnić, Danijela
AU  - Nikačević, Nikola
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4119
AB  - A detailed transient tridimensional CFD model of the turbulent flow of liquid phase inside of 26 mm diameter continuous oscillatory baffled reactor (COBR) was developed using STAR CCM+ software. The model considered a large number of COBR cavities separated with single-orifice baffles. The CFD model was validated using residence time distribution experiments with several flowrates and frequencies. Different from previous studies, flow oscillations in our work were generated using a membrane pump, which enabled lower amounts of backflow. Simulations were used to analyse flow patterns and mixing for several values of inlet flowrate and oscillation frequencies.
PB  - Elsevier Science Bv, Amsterdam
T2  - 29th European Symposium on Computer Aided Process Engineering, Pt A
T1  - Turbulent flow modeling in continuous oscillatory flow baffled reactor using STAR CCM
EP  - 846
SP  - 841
VL  - 46
DO  - 10.1016/B978-0-12-818634-3.50141-7
ER  - 

@article{
author = "Kljajić, Nikola and Todić, Branislav and Slavnić, Danijela and Nikačević, Nikola",
year = "2019",
abstract = "A detailed transient tridimensional CFD model of the turbulent flow of liquid phase inside of 26 mm diameter continuous oscillatory baffled reactor (COBR) was developed using STAR CCM+ software. The model considered a large number of COBR cavities separated with single-orifice baffles. The CFD model was validated using residence time distribution experiments with several flowrates and frequencies. Different from previous studies, flow oscillations in our work were generated using a membrane pump, which enabled lower amounts of backflow. Simulations were used to analyse flow patterns and mixing for several values of inlet flowrate and oscillation frequencies.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "29th European Symposium on Computer Aided Process Engineering, Pt A",
title = "Turbulent flow modeling in continuous oscillatory flow baffled reactor using STAR CCM",
pages = "846-841",
volume = "46",
doi = "10.1016/B978-0-12-818634-3.50141-7"
}

Kljajić, N., Todić, B., Slavnić, D.,& Nikačević, N.. (2019). Turbulent flow modeling in continuous oscillatory flow baffled reactor using STAR CCM. in 29th European Symposium on Computer Aided Process Engineering, Pt A
Elsevier Science Bv, Amsterdam., 46, 841-846.
https://doi.org/10.1016/B978-0-12-818634-3.50141-7

Kljajić N, Todić B, Slavnić D, Nikačević N. Turbulent flow modeling in continuous oscillatory flow baffled reactor using STAR CCM. in 29th European Symposium on Computer Aided Process Engineering, Pt A. 2019;46:841-846.
doi:10.1016/B978-0-12-818634-3.50141-7 .

Kljajić, Nikola, Todić, Branislav, Slavnić, Danijela, Nikačević, Nikola, "Turbulent flow modeling in continuous oscillatory flow baffled reactor using STAR CCM" in 29th European Symposium on Computer Aided Process Engineering, Pt A, 46 (2019):841-846,
https://doi.org/10.1016/B978-0-12-818634-3.50141-7 . .

TY  - JOUR
AU  - Bukur, Dragomir B.
AU  - Mandić, Miloš
AU  - Todić, Branislav
AU  - Nikačević, Nikola
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4132
PB  - Amer Chemical Soc, Washington
T2  - Abstracts of Papers of the American Chemical Society
T1  - Influence of intraparticle diffusion on effectiveness factor and methane selectivity of a cobalt based Fischer-Tropsch catalyst
VL  - 258
UR  - https://hdl.handle.net/21.15107/rcub_technorep_4132
ER  - 

@article{
author = "Bukur, Dragomir B. and Mandić, Miloš and Todić, Branislav and Nikačević, Nikola",
year = "2019",
publisher = "Amer Chemical Soc, Washington",
journal = "Abstracts of Papers of the American Chemical Society",
title = "Influence of intraparticle diffusion on effectiveness factor and methane selectivity of a cobalt based Fischer-Tropsch catalyst",
volume = "258",
url = "https://hdl.handle.net/21.15107/rcub_technorep_4132"
}

Bukur, D. B., Mandić, M., Todić, B.,& Nikačević, N.. (2019). Influence of intraparticle diffusion on effectiveness factor and methane selectivity of a cobalt based Fischer-Tropsch catalyst. in Abstracts of Papers of the American Chemical Society
Amer Chemical Soc, Washington., 258.
https://hdl.handle.net/21.15107/rcub_technorep_4132

Bukur DB, Mandić M, Todić B, Nikačević N. Influence of intraparticle diffusion on effectiveness factor and methane selectivity of a cobalt based Fischer-Tropsch catalyst. in Abstracts of Papers of the American Chemical Society. 2019;258.
https://hdl.handle.net/21.15107/rcub_technorep_4132 .

Bukur, Dragomir B., Mandić, Miloš, Todić, Branislav, Nikačević, Nikola, "Influence of intraparticle diffusion on effectiveness factor and methane selectivity of a cobalt based Fischer-Tropsch catalyst" in Abstracts of Papers of the American Chemical Society, 258 (2019),
https://hdl.handle.net/21.15107/rcub_technorep_4132 .

TY  - JOUR
AU  - Zivanić, Ljiljana
AU  - Stamenić, Marko
AU  - Todić, Branislav
AU  - Bukur, Dragomir B.
AU  - Nikačević, Nikola
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4246
AB  - Predictions of vapor liquid equilibrium for Fischer-Tropsch mixtures were com-pared using the classical Soave-Redlich-Kwong (SRK) and cubic-plus-asso-ciation (CPA) equations of state. The performance of the two equations of state was evaluated based on comparison with results from eight sets of exp-erimental runs in which different process conditions (pressure, reactants feed ratio, space velocity) were used. Flash calculations were used to determine the phase split at defined process conditions, whereas the phase equilibrium was defined utilizing the concept of equal fugacities in the vapor and the liquid phase for all components. A total of 75 components were considered in the reaction mixture: CO, H-2, H2O, CO2, C-1-C-57 paraffins and C-2-C-15 olefins. All calculations were performed in MATLAB. The results showed that both equat-ions of state had similar performance regarding the hydrocarbons, whereas CPA gave better results with inorganic components and SRK with prediction of the composition of the liquid phase. Computational time for CPA was sub-stantially (100 times with the CPU used) higher than that for SRK. Overall, the use of CPA did not improve VLE prediction for FTS systems significantly enough to be recommended for use in FTS reactor models.
PB  - Savez hemijskih inženjera, Beograd
T2  - Chemical Industry & Chemical Engineering Quarterly
T1  - Comparison of cubic-plus-association and soave-redlich-kwong equations of state for prediction of vapor-liquid equilibrium of fischer-tropsch reaction mixture
EP  - 76
IS  - 1
SP  - 67
VL  - 25
DO  - 10.2298/CICEQ180403018Z
ER  - 

@article{
author = "Zivanić, Ljiljana and Stamenić, Marko and Todić, Branislav and Bukur, Dragomir B. and Nikačević, Nikola",
year = "2019",
abstract = "Predictions of vapor liquid equilibrium for Fischer-Tropsch mixtures were com-pared using the classical Soave-Redlich-Kwong (SRK) and cubic-plus-asso-ciation (CPA) equations of state. The performance of the two equations of state was evaluated based on comparison with results from eight sets of exp-erimental runs in which different process conditions (pressure, reactants feed ratio, space velocity) were used. Flash calculations were used to determine the phase split at defined process conditions, whereas the phase equilibrium was defined utilizing the concept of equal fugacities in the vapor and the liquid phase for all components. A total of 75 components were considered in the reaction mixture: CO, H-2, H2O, CO2, C-1-C-57 paraffins and C-2-C-15 olefins. All calculations were performed in MATLAB. The results showed that both equat-ions of state had similar performance regarding the hydrocarbons, whereas CPA gave better results with inorganic components and SRK with prediction of the composition of the liquid phase. Computational time for CPA was sub-stantially (100 times with the CPU used) higher than that for SRK. Overall, the use of CPA did not improve VLE prediction for FTS systems significantly enough to be recommended for use in FTS reactor models.",
publisher = "Savez hemijskih inženjera, Beograd",
journal = "Chemical Industry & Chemical Engineering Quarterly",
title = "Comparison of cubic-plus-association and soave-redlich-kwong equations of state for prediction of vapor-liquid equilibrium of fischer-tropsch reaction mixture",
pages = "76-67",
number = "1",
volume = "25",
doi = "10.2298/CICEQ180403018Z"
}

Zivanić, L., Stamenić, M., Todić, B., Bukur, D. B.,& Nikačević, N.. (2019). Comparison of cubic-plus-association and soave-redlich-kwong equations of state for prediction of vapor-liquid equilibrium of fischer-tropsch reaction mixture. in Chemical Industry & Chemical Engineering Quarterly
Savez hemijskih inženjera, Beograd., 25(1), 67-76.
https://doi.org/10.2298/CICEQ180403018Z

Zivanić L, Stamenić M, Todić B, Bukur DB, Nikačević N. Comparison of cubic-plus-association and soave-redlich-kwong equations of state for prediction of vapor-liquid equilibrium of fischer-tropsch reaction mixture. in Chemical Industry & Chemical Engineering Quarterly. 2019;25(1):67-76.
doi:10.2298/CICEQ180403018Z .

Zivanić, Ljiljana, Stamenić, Marko, Todić, Branislav, Bukur, Dragomir B., Nikačević, Nikola, "Comparison of cubic-plus-association and soave-redlich-kwong equations of state for prediction of vapor-liquid equilibrium of fischer-tropsch reaction mixture" in Chemical Industry & Chemical Engineering Quarterly, 25, no. 1 (2019):67-76,
https://doi.org/10.2298/CICEQ180403018Z . .

TY  - JOUR
AU  - Mandić, Miloš
AU  - Dikić, Vladimir
AU  - Petkovska, Menka
AU  - Todić, Branislav
AU  - Bukur, Dragomir B.
AU  - Nikačević, Nikola
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3846
AB  - Dynamic performance of a milli-scale fixed bed reactor for Fischer-Tropsch synthesis (FTS) was studied using a dynamic pseudo-homogeneous 1D reactor model. The model uses detailed kinetics to describe the rates of FTS product formation. Dynamic responses of the process variables and main performance indicators, including productivity of C-5(+) hydrocarbons and CH4 selectivity, to input step changes, were analyzed. Total of 7 inlet variables were used in step-change-response analysis, with different magnitudes of change and for two initial steady-state conditions. Reactor simulations show highly nonlinear behavior due to phenomena coupling and fast dynamics due to system small scale and intensified rates within. In addition, reactor model shows instability related to thermal runaway with certain magnitudes of step change of coolant temperature and feed flow rate. The analysis outlines the effects of potential process disturbances on operation of milli-scale fixed bed reactor for FTS and provides general guidelines for control systems.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Chemical Engineering Science
T1  - Dynamic analysis of millimetre-scale fixed bed reactors for Fischer-Tropsch synthesis
EP  - 447
SP  - 434
VL  - 192
DO  - 10.1016/j.ces.2018.07.052
ER  - 

@article{
author = "Mandić, Miloš and Dikić, Vladimir and Petkovska, Menka and Todić, Branislav and Bukur, Dragomir B. and Nikačević, Nikola",
year = "2018",
abstract = "Dynamic performance of a milli-scale fixed bed reactor for Fischer-Tropsch synthesis (FTS) was studied using a dynamic pseudo-homogeneous 1D reactor model. The model uses detailed kinetics to describe the rates of FTS product formation. Dynamic responses of the process variables and main performance indicators, including productivity of C-5(+) hydrocarbons and CH4 selectivity, to input step changes, were analyzed. Total of 7 inlet variables were used in step-change-response analysis, with different magnitudes of change and for two initial steady-state conditions. Reactor simulations show highly nonlinear behavior due to phenomena coupling and fast dynamics due to system small scale and intensified rates within. In addition, reactor model shows instability related to thermal runaway with certain magnitudes of step change of coolant temperature and feed flow rate. The analysis outlines the effects of potential process disturbances on operation of milli-scale fixed bed reactor for FTS and provides general guidelines for control systems.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Chemical Engineering Science",
title = "Dynamic analysis of millimetre-scale fixed bed reactors for Fischer-Tropsch synthesis",
pages = "447-434",
volume = "192",
doi = "10.1016/j.ces.2018.07.052"
}

Mandić, M., Dikić, V., Petkovska, M., Todić, B., Bukur, D. B.,& Nikačević, N.. (2018). Dynamic analysis of millimetre-scale fixed bed reactors for Fischer-Tropsch synthesis. in Chemical Engineering Science
Pergamon-Elsevier Science Ltd, Oxford., 192, 434-447.
https://doi.org/10.1016/j.ces.2018.07.052

Mandić M, Dikić V, Petkovska M, Todić B, Bukur DB, Nikačević N. Dynamic analysis of millimetre-scale fixed bed reactors for Fischer-Tropsch synthesis. in Chemical Engineering Science. 2018;192:434-447.
doi:10.1016/j.ces.2018.07.052 .

Mandić, Miloš, Dikić, Vladimir, Petkovska, Menka, Todić, Branislav, Bukur, Dragomir B., Nikačević, Nikola, "Dynamic analysis of millimetre-scale fixed bed reactors for Fischer-Tropsch synthesis" in Chemical Engineering Science, 192 (2018):434-447,
https://doi.org/10.1016/j.ces.2018.07.052 . .

TY  - JOUR
AU  - Stamenić, Marko
AU  - Dikić, Vladimir
AU  - Mandić, Miloš
AU  - Todić, Branislav
AU  - Bukur, Dragomir B.
AU  - Nikačević, Nikola
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3964
AB  - Our previously developed mathematical model is used for parametric sensitivity and optimization study of conventional and milliscale fixed-bed reactors (FBRs) for Fischer-Tropsch synthesis (FTS). Five indicators are chosen to analyze the influence of eight parameters on the FBRs performance. The results show the scale of the effects caused by changing single parameter values and highlight the most important ones. Subsequently, the model is used to perform a rigorous multivariable optimization of the FBRs performance in the steady state. Three optimization functions are used, depicting different reactor costs. Four design parameters (tube length and diameter, particle diameter, and catalyst layer thickness) and five operating parameters (inlet and wall temperature, inlet pressure, H-2/CO ratio, velocity) are optimized simultaneously. The results indicate that optimal results, in terms of reactor design and operating parameters and FBR performance, highly depend on the selected objective function and values of constrained parameters (especially methane selectivity and the partial pressure of water).
PB  - Amer Chemical Soc, Washington
T2  - Industrial & Engineering Chemistry Research
T1  - Multiscale and Multiphase Model of Fixed-Bed Reactors for Fischer-Tropsch Synthesis: Optimization Study
EP  - 3162
IS  - 9
SP  - 3149
VL  - 57
DO  - 10.1021/acs.iecr.7b04914
ER  - 

@article{
author = "Stamenić, Marko and Dikić, Vladimir and Mandić, Miloš and Todić, Branislav and Bukur, Dragomir B. and Nikačević, Nikola",
year = "2018",
abstract = "Our previously developed mathematical model is used for parametric sensitivity and optimization study of conventional and milliscale fixed-bed reactors (FBRs) for Fischer-Tropsch synthesis (FTS). Five indicators are chosen to analyze the influence of eight parameters on the FBRs performance. The results show the scale of the effects caused by changing single parameter values and highlight the most important ones. Subsequently, the model is used to perform a rigorous multivariable optimization of the FBRs performance in the steady state. Three optimization functions are used, depicting different reactor costs. Four design parameters (tube length and diameter, particle diameter, and catalyst layer thickness) and five operating parameters (inlet and wall temperature, inlet pressure, H-2/CO ratio, velocity) are optimized simultaneously. The results indicate that optimal results, in terms of reactor design and operating parameters and FBR performance, highly depend on the selected objective function and values of constrained parameters (especially methane selectivity and the partial pressure of water).",
publisher = "Amer Chemical Soc, Washington",
journal = "Industrial & Engineering Chemistry Research",
title = "Multiscale and Multiphase Model of Fixed-Bed Reactors for Fischer-Tropsch Synthesis: Optimization Study",
pages = "3162-3149",
number = "9",
volume = "57",
doi = "10.1021/acs.iecr.7b04914"
}

Stamenić, M., Dikić, V., Mandić, M., Todić, B., Bukur, D. B.,& Nikačević, N.. (2018). Multiscale and Multiphase Model of Fixed-Bed Reactors for Fischer-Tropsch Synthesis: Optimization Study. in Industrial & Engineering Chemistry Research
Amer Chemical Soc, Washington., 57(9), 3149-3162.
https://doi.org/10.1021/acs.iecr.7b04914

Stamenić M, Dikić V, Mandić M, Todić B, Bukur DB, Nikačević N. Multiscale and Multiphase Model of Fixed-Bed Reactors for Fischer-Tropsch Synthesis: Optimization Study. in Industrial & Engineering Chemistry Research. 2018;57(9):3149-3162.
doi:10.1021/acs.iecr.7b04914 .

Stamenić, Marko, Dikić, Vladimir, Mandić, Miloš, Todić, Branislav, Bukur, Dragomir B., Nikačević, Nikola, "Multiscale and Multiphase Model of Fixed-Bed Reactors for Fischer-Tropsch Synthesis: Optimization Study" in Industrial & Engineering Chemistry Research, 57, no. 9 (2018):3149-3162,
https://doi.org/10.1021/acs.iecr.7b04914 . .

TY  - JOUR
AU  - Todić, Branislav
AU  - Mandić, Miloš
AU  - Nikačević, Nikola
AU  - Bukur, Dragomir B.
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3996
AB  - A two-dimensional pseudo-homogeneous model of wall-cooled fixed bed Fischer-Tropsch synthesis (FTS) reactor with Co/Re/gamma-Al2O3 catalyst was developed to study the effect of process and design parameters on heat generation and removal characteristics. The influence of liquid-phase formation on heat transport was accounted for by using two-phase correlations. The effect of intraparticle diffusion on heat generation was considered. Detailed numerical simulations were performed to analyze the effect of process and design parameters on the reactor performance in terms of heat management. Results show that thermal behavior of FTS fixed bed reactors is very sensitive and any large disturbances can lead to temperature runaway. Large tube diameters are shown to be particularly unfavorable, with d (t)  gt  5 cm resulting in axial and radial gradients greater than 20 K and 13 K, respectively. The importance of detailed reactor modeling when designing and optimizing FTS fixed bed reactors is highlighted.
PB  - Korean Institute Chemical  Engineers, Seoul
T2  - Korean Journal of Chemical Engineering
T1  - Effects of process and design parameters on heat management in fixed bed Fischer-Tropsch synthesis reactor
EP  - 889
IS  - 4
SP  - 875
VL  - 35
DO  - 10.1007/s11814-017-0335-3
ER  - 

@article{
author = "Todić, Branislav and Mandić, Miloš and Nikačević, Nikola and Bukur, Dragomir B.",
year = "2018",
abstract = "A two-dimensional pseudo-homogeneous model of wall-cooled fixed bed Fischer-Tropsch synthesis (FTS) reactor with Co/Re/gamma-Al2O3 catalyst was developed to study the effect of process and design parameters on heat generation and removal characteristics. The influence of liquid-phase formation on heat transport was accounted for by using two-phase correlations. The effect of intraparticle diffusion on heat generation was considered. Detailed numerical simulations were performed to analyze the effect of process and design parameters on the reactor performance in terms of heat management. Results show that thermal behavior of FTS fixed bed reactors is very sensitive and any large disturbances can lead to temperature runaway. Large tube diameters are shown to be particularly unfavorable, with d (t)  gt  5 cm resulting in axial and radial gradients greater than 20 K and 13 K, respectively. The importance of detailed reactor modeling when designing and optimizing FTS fixed bed reactors is highlighted.",
publisher = "Korean Institute Chemical  Engineers, Seoul",
journal = "Korean Journal of Chemical Engineering",
title = "Effects of process and design parameters on heat management in fixed bed Fischer-Tropsch synthesis reactor",
pages = "889-875",
number = "4",
volume = "35",
doi = "10.1007/s11814-017-0335-3"
}

Todić, B., Mandić, M., Nikačević, N.,& Bukur, D. B.. (2018). Effects of process and design parameters on heat management in fixed bed Fischer-Tropsch synthesis reactor. in Korean Journal of Chemical Engineering
Korean Institute Chemical  Engineers, Seoul., 35(4), 875-889.
https://doi.org/10.1007/s11814-017-0335-3

Todić B, Mandić M, Nikačević N, Bukur DB. Effects of process and design parameters on heat management in fixed bed Fischer-Tropsch synthesis reactor. in Korean Journal of Chemical Engineering. 2018;35(4):875-889.
doi:10.1007/s11814-017-0335-3 .

Todić, Branislav, Mandić, Miloš, Nikačević, Nikola, Bukur, Dragomir B., "Effects of process and design parameters on heat management in fixed bed Fischer-Tropsch synthesis reactor" in Korean Journal of Chemical Engineering, 35, no. 4 (2018):875-889,
https://doi.org/10.1007/s11814-017-0335-3 . .

TY  - CONF
AU  - Todić, Branislav
AU  - Mandić, M.
AU  - Nikačević, Nikola
AU  - Bukur, Dragomir B.
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3481
PB  - Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Meeting
C3  - Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Me
T1  - Heat generation and removal in fixed-bed reactors for fischer-tropsch synthesis
EP  - 474
SP  - 471
VL  - 2
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3481
ER  - 

@conference{
author = "Todić, Branislav and Mandić, M. and Nikačević, Nikola and Bukur, Dragomir B.",
year = "2017",
publisher = "Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Meeting",
journal = "Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Me",
title = "Heat generation and removal in fixed-bed reactors for fischer-tropsch synthesis",
pages = "474-471",
volume = "2",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3481"
}

Todić, B., Mandić, M., Nikačević, N.,& Bukur, D. B.. (2017). Heat generation and removal in fixed-bed reactors for fischer-tropsch synthesis. in Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Me
Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Meeting., 2, 471-474.
https://hdl.handle.net/21.15107/rcub_technorep_3481

Todić B, Mandić M, Nikačević N, Bukur DB. Heat generation and removal in fixed-bed reactors for fischer-tropsch synthesis. in Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Me. 2017;2:471-474.
https://hdl.handle.net/21.15107/rcub_technorep_3481 .

Todić, Branislav, Mandić, M., Nikačević, Nikola, Bukur, Dragomir B., "Heat generation and removal in fixed-bed reactors for fischer-tropsch synthesis" in Catalysis and Reaction Engineering Division 2017 - Core Programming Area at the 2017 AIChE Annual Me, 2 (2017):471-474,
https://hdl.handle.net/21.15107/rcub_technorep_3481 .

TY  - JOUR
AU  - Stamenić, Marko
AU  - Dikić, Vladimir
AU  - Mandić, Miloš
AU  - Todić, Branislav
AU  - Bukur, Dragomir B.
AU  - Nikačević, Nikola
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3542
AB  - A multiphase fixed-bed reactor (FBR) model for Fischer Tropsch Synthesis has been developed. A high level of details is considered for description of the phenomena on the reactor and particle scale. Detailed kinetics is used, with parameters estimated from experiments with a cobalt-based catalyst. Model robustness has been validated using literature data. Performance analysis was made for a conventional scale FBR with egg-shell distribution of catalyst and a millimeter-scale FBR with small particles and uniform distribution. In both cases, diffusion limitations are almost eliminated due to use of small diffusion lengths. For similar qualitative results, a milli-scaled design would result in a significantly lower reactor volume, but the capital costs could be high due to large wall area and a vast number of tubes. Heat removal is efficient in both cases, and pressure drop in the milli-scale reactor is low due to the use of a shorter bed and lower velocity.
PB  - Amer Chemical Soc, Washington
T2  - Industrial & Engineering Chemistry Research
T1  - Multiscale and Multiphase Model of Fixed Bed Reactors for Fischer-Tropsch Synthesis: Intensification Possibilities Study
EP  - 9979
IS  - 36
SP  - 9964
VL  - 56
DO  - 10.1021/acs.iecr.7b02467
ER  - 

@article{
author = "Stamenić, Marko and Dikić, Vladimir and Mandić, Miloš and Todić, Branislav and Bukur, Dragomir B. and Nikačević, Nikola",
year = "2017",
abstract = "A multiphase fixed-bed reactor (FBR) model for Fischer Tropsch Synthesis has been developed. A high level of details is considered for description of the phenomena on the reactor and particle scale. Detailed kinetics is used, with parameters estimated from experiments with a cobalt-based catalyst. Model robustness has been validated using literature data. Performance analysis was made for a conventional scale FBR with egg-shell distribution of catalyst and a millimeter-scale FBR with small particles and uniform distribution. In both cases, diffusion limitations are almost eliminated due to use of small diffusion lengths. For similar qualitative results, a milli-scaled design would result in a significantly lower reactor volume, but the capital costs could be high due to large wall area and a vast number of tubes. Heat removal is efficient in both cases, and pressure drop in the milli-scale reactor is low due to the use of a shorter bed and lower velocity.",
publisher = "Amer Chemical Soc, Washington",
journal = "Industrial & Engineering Chemistry Research",
title = "Multiscale and Multiphase Model of Fixed Bed Reactors for Fischer-Tropsch Synthesis: Intensification Possibilities Study",
pages = "9979-9964",
number = "36",
volume = "56",
doi = "10.1021/acs.iecr.7b02467"
}

Stamenić, M., Dikić, V., Mandić, M., Todić, B., Bukur, D. B.,& Nikačević, N.. (2017). Multiscale and Multiphase Model of Fixed Bed Reactors for Fischer-Tropsch Synthesis: Intensification Possibilities Study. in Industrial & Engineering Chemistry Research
Amer Chemical Soc, Washington., 56(36), 9964-9979.
https://doi.org/10.1021/acs.iecr.7b02467

Stamenić M, Dikić V, Mandić M, Todić B, Bukur DB, Nikačević N. Multiscale and Multiphase Model of Fixed Bed Reactors for Fischer-Tropsch Synthesis: Intensification Possibilities Study. in Industrial & Engineering Chemistry Research. 2017;56(36):9964-9979.
doi:10.1021/acs.iecr.7b02467 .

Stamenić, Marko, Dikić, Vladimir, Mandić, Miloš, Todić, Branislav, Bukur, Dragomir B., Nikačević, Nikola, "Multiscale and Multiphase Model of Fixed Bed Reactors for Fischer-Tropsch Synthesis: Intensification Possibilities Study" in Industrial & Engineering Chemistry Research, 56, no. 36 (2017):9964-9979,
https://doi.org/10.1021/acs.iecr.7b02467 . .

TY  - JOUR
AU  - Todić, Branislav
AU  - Ma, Wenping
AU  - Jacobs, Gary
AU  - Nikačević, Nikola
AU  - Davis, Burtron H.
AU  - Bukur, Dragomir B.
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3678
AB  - A detailed kinetic model of Fischer-Tropsch synthesis (FTS) product formation, including secondary methane formation and 1-olefin hydrogenation, has been developed. Methane formation in FTS over the cobalt-based catalyst is well known to be higher-than-expected compared to other n-paraffin products under typical reaction conditions. A novel model proposes secondary methane formation on a different type of active site, which is not active in forming C2+ products, to explain this anomalous methane behavior. In addition, a model of secondary 1-olefin hydrogenation has also been developed. Secondary 1-olefin hydrogenation is related to secondary methane formation with both reactions happening on the same type of active sites. The model parameters were estimated from experimental data obtained with Co/Re/-Al2O3 catalyst in a slurry-phase stirred tank reactor over a range of conditions (T = 478, 493, and 503 K, P = 1.5 and 2.5 MPa, H-2/CO feed ratio = 1.4 and 2.1, and X-CO = 16-62%). The proposed model including secondary methane formation and 1-olefin hydrogenation is shown to provide an improved quantitative and qualitative prediction of experimentally observed behavior compared to the detailed model with only primary reactions.
PB  - Wiley, Hoboken
T2  - International Journal of Chemical Kinetics
T1  - Kinetic Modeling of Secondary Methane Formation and 1-Olefin Hydrogenation in Fischer-Tropsch Synthesis over a Cobalt Catalyst
EP  - 874
IS  - 12
SP  - 859
VL  - 49
DO  - 10.1002/kin.21133
ER  - 

@article{
author = "Todić, Branislav and Ma, Wenping and Jacobs, Gary and Nikačević, Nikola and Davis, Burtron H. and Bukur, Dragomir B.",
year = "2017",
abstract = "A detailed kinetic model of Fischer-Tropsch synthesis (FTS) product formation, including secondary methane formation and 1-olefin hydrogenation, has been developed. Methane formation in FTS over the cobalt-based catalyst is well known to be higher-than-expected compared to other n-paraffin products under typical reaction conditions. A novel model proposes secondary methane formation on a different type of active site, which is not active in forming C2+ products, to explain this anomalous methane behavior. In addition, a model of secondary 1-olefin hydrogenation has also been developed. Secondary 1-olefin hydrogenation is related to secondary methane formation with both reactions happening on the same type of active sites. The model parameters were estimated from experimental data obtained with Co/Re/-Al2O3 catalyst in a slurry-phase stirred tank reactor over a range of conditions (T = 478, 493, and 503 K, P = 1.5 and 2.5 MPa, H-2/CO feed ratio = 1.4 and 2.1, and X-CO = 16-62%). The proposed model including secondary methane formation and 1-olefin hydrogenation is shown to provide an improved quantitative and qualitative prediction of experimentally observed behavior compared to the detailed model with only primary reactions.",
publisher = "Wiley, Hoboken",
journal = "International Journal of Chemical Kinetics",
title = "Kinetic Modeling of Secondary Methane Formation and 1-Olefin Hydrogenation in Fischer-Tropsch Synthesis over a Cobalt Catalyst",
pages = "874-859",
number = "12",
volume = "49",
doi = "10.1002/kin.21133"
}

Todić, B., Ma, W., Jacobs, G., Nikačević, N., Davis, B. H.,& Bukur, D. B.. (2017). Kinetic Modeling of Secondary Methane Formation and 1-Olefin Hydrogenation in Fischer-Tropsch Synthesis over a Cobalt Catalyst. in International Journal of Chemical Kinetics
Wiley, Hoboken., 49(12), 859-874.
https://doi.org/10.1002/kin.21133

Todić B, Ma W, Jacobs G, Nikačević N, Davis BH, Bukur DB. Kinetic Modeling of Secondary Methane Formation and 1-Olefin Hydrogenation in Fischer-Tropsch Synthesis over a Cobalt Catalyst. in International Journal of Chemical Kinetics. 2017;49(12):859-874.
doi:10.1002/kin.21133 .

Todić, Branislav, Ma, Wenping, Jacobs, Gary, Nikačević, Nikola, Davis, Burtron H., Bukur, Dragomir B., "Kinetic Modeling of Secondary Methane Formation and 1-Olefin Hydrogenation in Fischer-Tropsch Synthesis over a Cobalt Catalyst" in International Journal of Chemical Kinetics, 49, no. 12 (2017):859-874,
https://doi.org/10.1002/kin.21133 . .

TY  - JOUR
AU  - Mandić, Miloš
AU  - Todić, Branislav
AU  - Zivanić, Ljiljana
AU  - Nikačević, Nikola
AU  - Bukur, Dragomir B.
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3688
AB  - We investigate effects of catalyst activity, catalyst particle shape (sphere, slab, and hollow cylinder), size (i.e., diffusion length), catalyst distribution (uniform vs eggshell type distribution for a spherical particle), and process conditions (temperature, pressure, syngas composition, and conversion level) on catalyst effectiveness factor and methane selectivity inside the catalyst pellet. In numerical simulations we utilize kinetic parameters for CO consumption rate and CH4 formation rate determined from experiments with a highly active Co/Re/gamma-Al2O3 catalyst. It is found that the use of small spherical particles (0.2-0.5 mm) or eggshell distribution for larger spherical particles with catalyst layer thickness less than approximately 0.13 mm is needed to avoid negative impact of diffusional limitations on CH4 selectivity under typical Fischer Tropsch synthesis operating conditions. For monolith reactors with wash-coated catalyst, diffusional limitations can be avoided by using a catalyst layer thickness less than 0.11 nun at base case conditions (473 K, 25 bar, and H-2/CO molar ratio of 2).
PB  - Amer Chemical Soc, Washington
T2  - Industrial & Engineering Chemistry Research
T1  - Effects of Catalyst Activity, Particle Size and Shape, and Process Conditions on Catalyst Effectiveness and Methane Selectivity for Fischer-Tropsch Reaction: A Modeling Study
EP  - 2745
IS  - 10
SP  - 2733
VL  - 56
DO  - 10.1021/acs.iecr.7b00053
ER  - 

@article{
author = "Mandić, Miloš and Todić, Branislav and Zivanić, Ljiljana and Nikačević, Nikola and Bukur, Dragomir B.",
year = "2017",
abstract = "We investigate effects of catalyst activity, catalyst particle shape (sphere, slab, and hollow cylinder), size (i.e., diffusion length), catalyst distribution (uniform vs eggshell type distribution for a spherical particle), and process conditions (temperature, pressure, syngas composition, and conversion level) on catalyst effectiveness factor and methane selectivity inside the catalyst pellet. In numerical simulations we utilize kinetic parameters for CO consumption rate and CH4 formation rate determined from experiments with a highly active Co/Re/gamma-Al2O3 catalyst. It is found that the use of small spherical particles (0.2-0.5 mm) or eggshell distribution for larger spherical particles with catalyst layer thickness less than approximately 0.13 mm is needed to avoid negative impact of diffusional limitations on CH4 selectivity under typical Fischer Tropsch synthesis operating conditions. For monolith reactors with wash-coated catalyst, diffusional limitations can be avoided by using a catalyst layer thickness less than 0.11 nun at base case conditions (473 K, 25 bar, and H-2/CO molar ratio of 2).",
publisher = "Amer Chemical Soc, Washington",
journal = "Industrial & Engineering Chemistry Research",
title = "Effects of Catalyst Activity, Particle Size and Shape, and Process Conditions on Catalyst Effectiveness and Methane Selectivity for Fischer-Tropsch Reaction: A Modeling Study",
pages = "2745-2733",
number = "10",
volume = "56",
doi = "10.1021/acs.iecr.7b00053"
}

Mandić, M., Todić, B., Zivanić, L., Nikačević, N.,& Bukur, D. B.. (2017). Effects of Catalyst Activity, Particle Size and Shape, and Process Conditions on Catalyst Effectiveness and Methane Selectivity for Fischer-Tropsch Reaction: A Modeling Study. in Industrial & Engineering Chemistry Research
Amer Chemical Soc, Washington., 56(10), 2733-2745.
https://doi.org/10.1021/acs.iecr.7b00053

Mandić M, Todić B, Zivanić L, Nikačević N, Bukur DB. Effects of Catalyst Activity, Particle Size and Shape, and Process Conditions on Catalyst Effectiveness and Methane Selectivity for Fischer-Tropsch Reaction: A Modeling Study. in Industrial & Engineering Chemistry Research. 2017;56(10):2733-2745.
doi:10.1021/acs.iecr.7b00053 .

Mandić, Miloš, Todić, Branislav, Zivanić, Ljiljana, Nikačević, Nikola, Bukur, Dragomir B., "Effects of Catalyst Activity, Particle Size and Shape, and Process Conditions on Catalyst Effectiveness and Methane Selectivity for Fischer-Tropsch Reaction: A Modeling Study" in Industrial & Engineering Chemistry Research, 56, no. 10 (2017):2733-2745,
https://doi.org/10.1021/acs.iecr.7b00053 . .

TY  - JOUR
AU  - Todić, Branislav
AU  - Nowicki, Lech
AU  - Nikačević, Nikola
AU  - Bukur, Dragomir B.
PY  - 2016
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3411
AB  - The effect of process conditions on product selectivity of Fischer-Tropsch synthesis (FTS) over industrial iron-based catalyst (100 Fe/5 Cu/4.2 K/25 SiO2) was studied in a 1-L stirred tank slurry reactor. Experiments were performed over a range of different reaction conditions, including three temperatures (T = 493, 513 and 533K), four pressures (P = 0.8, 1.5, 2.25 and 2.5 MPa), two synthesis gas feed molar ratios (H-2/CO = 0.67 and 2) and gas space velocity from 0.52 to 23.5 Ndm(3)/g-Fe/h. The effect of process conditions on reaction pathways of FTS and secondary 1-olefin reactions was analyzed by comparing product selectivities, chain growth probabilities and ratios of main products (n-paraffin, 1- and 2-olefin). Reduction of methane production and increase of C5+ products was achieved by decreasing temperature, inlet H-2/CO ratio and/or increasing pressure. Overall selectivity toward methane and C5+ did not show significant changes with variations in residence time. All of the product selectivity variations were shown to be related to changes in chain length dependent growth probabilities.
PB  - Elsevier Science Bv, Amsterdam
T2  - Catalysis Today
T1  - Fischer-Tropsch synthesis product selectivity over an industrial iron-based catalyst: Effect of process conditions
EP  - 39
SP  - 28
VL  - 261
DO  - 10.1016/j.cattod.2015.09.005
ER  - 

@article{
author = "Todić, Branislav and Nowicki, Lech and Nikačević, Nikola and Bukur, Dragomir B.",
year = "2016",
abstract = "The effect of process conditions on product selectivity of Fischer-Tropsch synthesis (FTS) over industrial iron-based catalyst (100 Fe/5 Cu/4.2 K/25 SiO2) was studied in a 1-L stirred tank slurry reactor. Experiments were performed over a range of different reaction conditions, including three temperatures (T = 493, 513 and 533K), four pressures (P = 0.8, 1.5, 2.25 and 2.5 MPa), two synthesis gas feed molar ratios (H-2/CO = 0.67 and 2) and gas space velocity from 0.52 to 23.5 Ndm(3)/g-Fe/h. The effect of process conditions on reaction pathways of FTS and secondary 1-olefin reactions was analyzed by comparing product selectivities, chain growth probabilities and ratios of main products (n-paraffin, 1- and 2-olefin). Reduction of methane production and increase of C5+ products was achieved by decreasing temperature, inlet H-2/CO ratio and/or increasing pressure. Overall selectivity toward methane and C5+ did not show significant changes with variations in residence time. All of the product selectivity variations were shown to be related to changes in chain length dependent growth probabilities.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Catalysis Today",
title = "Fischer-Tropsch synthesis product selectivity over an industrial iron-based catalyst: Effect of process conditions",
pages = "39-28",
volume = "261",
doi = "10.1016/j.cattod.2015.09.005"
}

Todić, B., Nowicki, L., Nikačević, N.,& Bukur, D. B.. (2016). Fischer-Tropsch synthesis product selectivity over an industrial iron-based catalyst: Effect of process conditions. in Catalysis Today
Elsevier Science Bv, Amsterdam., 261, 28-39.
https://doi.org/10.1016/j.cattod.2015.09.005

Todić B, Nowicki L, Nikačević N, Bukur DB. Fischer-Tropsch synthesis product selectivity over an industrial iron-based catalyst: Effect of process conditions. in Catalysis Today. 2016;261:28-39.
doi:10.1016/j.cattod.2015.09.005 .

Todić, Branislav, Nowicki, Lech, Nikačević, Nikola, Bukur, Dragomir B., "Fischer-Tropsch synthesis product selectivity over an industrial iron-based catalyst: Effect of process conditions" in Catalysis Today, 261 (2016):28-39,
https://doi.org/10.1016/j.cattod.2015.09.005 . .

TY  - JOUR
AU  - Olewski, Tomasz
AU  - Todić, Branislav
AU  - Nowicki, Lech
AU  - Nikačević, Nikola
AU  - Bukur, Dragomir B.
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2972
AB  - Two kinetic models of Fischer-Tropsch product selectivity have been developed based on reaction networks from the literature. The models were fitted to experimental data obtained using commercial iron-based catalyst in a stirred tank slurry reactor and under a wide range of process conditions. Results showed that both of the rival models were able to provide a satisfactory prediction of the experimental product distribution for n-paraffin, 1- and 2-olefin. The simpler of the two models, a reaction network with a single type of active sites and solubility enhanced 1-olefin readsorption term, was chosen as more adequate for practical use.
PB  - Elsevier, Amsterdam
T2  - Chemical Engineering Research & Design
T1  - Hydrocarbon selectivity models for iron-based Fischer-Tropsch catalyst
EP  - 11
SP  - 1
VL  - 95
DO  - 10.1016/j.cherd.2014.12.015
ER  - 

@article{
author = "Olewski, Tomasz and Todić, Branislav and Nowicki, Lech and Nikačević, Nikola and Bukur, Dragomir B.",
year = "2015",
abstract = "Two kinetic models of Fischer-Tropsch product selectivity have been developed based on reaction networks from the literature. The models were fitted to experimental data obtained using commercial iron-based catalyst in a stirred tank slurry reactor and under a wide range of process conditions. Results showed that both of the rival models were able to provide a satisfactory prediction of the experimental product distribution for n-paraffin, 1- and 2-olefin. The simpler of the two models, a reaction network with a single type of active sites and solubility enhanced 1-olefin readsorption term, was chosen as more adequate for practical use.",
publisher = "Elsevier, Amsterdam",
journal = "Chemical Engineering Research & Design",
title = "Hydrocarbon selectivity models for iron-based Fischer-Tropsch catalyst",
pages = "11-1",
volume = "95",
doi = "10.1016/j.cherd.2014.12.015"
}

Olewski, T., Todić, B., Nowicki, L., Nikačević, N.,& Bukur, D. B.. (2015). Hydrocarbon selectivity models for iron-based Fischer-Tropsch catalyst. in Chemical Engineering Research & Design
Elsevier, Amsterdam., 95, 1-11.
https://doi.org/10.1016/j.cherd.2014.12.015

Olewski T, Todić B, Nowicki L, Nikačević N, Bukur DB. Hydrocarbon selectivity models for iron-based Fischer-Tropsch catalyst. in Chemical Engineering Research & Design. 2015;95:1-11.
doi:10.1016/j.cherd.2014.12.015 .

Olewski, Tomasz, Todić, Branislav, Nowicki, Lech, Nikačević, Nikola, Bukur, Dragomir B., "Hydrocarbon selectivity models for iron-based Fischer-Tropsch catalyst" in Chemical Engineering Research & Design, 95 (2015):1-11,
https://doi.org/10.1016/j.cherd.2014.12.015 . .

TY  - JOUR
AU  - Todić, Branislav
AU  - Ordomsky, Vitaly V.
AU  - Nikačević, Nikola
AU  - Khodakov, Andrei Y.
AU  - Bukur, Dragomir B.
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3032
AB  - Due to the global growth in production of synthetic fuels via the Gas-to-Liquid (GTL), Coal-To-Liquid (CTL) and Biomass-To-Liquid (BTL) processes, academic and industrial interest in Fischer-Tropsch synthesis (FTS) research has increased during the past decade. The undesired product of FTS is methane and it is formed in amounts higher than expected according to the current understanding of the FTS mechanism. Therefore, it is important to gain better understanding of methane formation in order to optimize the FTS process. In this review we discuss the reasons responsible for higher than expected methane selectivity under FTS conditions over cobalt-based FTS catalysts and describe novel microreactors for use in FTS. These novel reactors could help improve reaction selectivity and yield, as well as offer significant economic benefits. Recommendations are given for intensification of FTS in terms of product selectivity by improved selection of catalysts, process conditions and reactor configurations.
PB  - Royal Soc Chemistry, Cambridge
T2  - Catalysis Science & Technology
T1  - Opportunities for intensification of Fischer-Tropsch synthesis through reduced formation of methane over cobalt catalysts in microreactors
EP  - 1411
IS  - 3
SP  - 1400
VL  - 5
DO  - 10.1039/c4cy01547a
ER  - 

@article{
author = "Todić, Branislav and Ordomsky, Vitaly V. and Nikačević, Nikola and Khodakov, Andrei Y. and Bukur, Dragomir B.",
year = "2015",
abstract = "Due to the global growth in production of synthetic fuels via the Gas-to-Liquid (GTL), Coal-To-Liquid (CTL) and Biomass-To-Liquid (BTL) processes, academic and industrial interest in Fischer-Tropsch synthesis (FTS) research has increased during the past decade. The undesired product of FTS is methane and it is formed in amounts higher than expected according to the current understanding of the FTS mechanism. Therefore, it is important to gain better understanding of methane formation in order to optimize the FTS process. In this review we discuss the reasons responsible for higher than expected methane selectivity under FTS conditions over cobalt-based FTS catalysts and describe novel microreactors for use in FTS. These novel reactors could help improve reaction selectivity and yield, as well as offer significant economic benefits. Recommendations are given for intensification of FTS in terms of product selectivity by improved selection of catalysts, process conditions and reactor configurations.",
publisher = "Royal Soc Chemistry, Cambridge",
journal = "Catalysis Science & Technology",
title = "Opportunities for intensification of Fischer-Tropsch synthesis through reduced formation of methane over cobalt catalysts in microreactors",
pages = "1411-1400",
number = "3",
volume = "5",
doi = "10.1039/c4cy01547a"
}

Todić, B., Ordomsky, V. V., Nikačević, N., Khodakov, A. Y.,& Bukur, D. B.. (2015). Opportunities for intensification of Fischer-Tropsch synthesis through reduced formation of methane over cobalt catalysts in microreactors. in Catalysis Science & Technology
Royal Soc Chemistry, Cambridge., 5(3), 1400-1411.
https://doi.org/10.1039/c4cy01547a

Todić B, Ordomsky VV, Nikačević N, Khodakov AY, Bukur DB. Opportunities for intensification of Fischer-Tropsch synthesis through reduced formation of methane over cobalt catalysts in microreactors. in Catalysis Science & Technology. 2015;5(3):1400-1411.
doi:10.1039/c4cy01547a .

Todić, Branislav, Ordomsky, Vitaly V., Nikačević, Nikola, Khodakov, Andrei Y., Bukur, Dragomir B., "Opportunities for intensification of Fischer-Tropsch synthesis through reduced formation of methane over cobalt catalysts in microreactors" in Catalysis Science & Technology, 5, no. 3 (2015):1400-1411,
https://doi.org/10.1039/c4cy01547a . .

TY  - THES
AU  - Todić, Branislav
PY  - 2015
UR  - http://eteze.bg.ac.rs/application/showtheses?thesesId=3173
UR  - https://fedorabg.bg.ac.rs/fedora/get/o:11518/bdef:Content/download
UR  - http://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=47501583
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4622
AB  - Fischer-Tropsch synthesis (FTS) is a heterogeneously catalyzed chemical reaction in which a mixture of hydrogen and carbon-monoxide is converted into an array of hydrocarbon products. These products can be used as synthetic liquid fuels (gasoline, diesel, kerosene) or feedstock for the chemical industry. As such, FTS is a key step in the conversion of coal, natural gas and biomass into liquids in large plants all over the world, including plants in Qatar, Malaysia, South Africa etc. Even though FTS has been commercially used for most of the 20th century, many fundamental aspects of this reaction are unclear. The main objectives of the work included in this thesis were: to study the effect of process conditions on FTS product selectivity and distribution with regards to hydrocarbon chain length, develop a detailed model of FTS kinetics (capable of predicting both reactant disappearance and product formation rates) and apply the detailed kinetic model in modeling and optimization of a multi-tubular fixed-bed reactor for FTS. Most often used catalysts for FTS are iron and cobalt. The experimental data used in this study were obtained in collaboration with Texas A&M University and Center for Applied Energy Research, University of Kentucky, for iron- and cobalt-based catalyst, respectively. The analysis of experimental data for both catalysts showed dependence of product selectivity from process conditions inside the reactor (temperature, pressure, reactant feed ratio and conversion level). These dependences were shown to be related to the chain-growth probability factor (α), which also varies with carbon number. Over the cobalt catalyst, the significant variation of C1 intermediate growth probability (α1) at different process conditions and a lack of the same variations for higher C2+ chain intermediates, was interpreted as evidence for the existence of separate methanation pathways. The same data presented evidence that the secondary 1-olefin readsorption does not play a major part in determining FTS selectivity. For the iron-based catalysts, similar correlations between variations of growth probability with process conditions were found. However, existence of additional pathways for methane formation and relevance of secondary olefin reactions could not be confirmed for that catalyst...
AB  - Fischer-Tropsch sinteza (FTS) je heterogeno katalizovana hemijska reakcija u kojoj se smeša vodonika i ugljen-monoksida pretvara u niz ugljovodoničnih proizvoda. Ti proizvodi se mogu koristiti kao sintetička tečna goriva (benzin, dizel i kerozin) ili sirovine za hemijsku industriju. Kao takva, FTS je ključni korak u konverziji uglja, prirodnog gasa i biomase u tečnosti u velikim postrojenjima širom sveta, uključujući postrojenja u Kataru, Maleziji, Južnoj Africi itd. Iako je FTS veći deo dvadesetog veka bila u komercijalnoj upotrebi, mnogi fundamentalni aspekti ove reakcije su nejasni. Glavni ciljevi istraživačkog rada u sklopu ove disertacije su bili: ispitivanje efekata procesnih uslova na selektivnost i raspodelu FTS proizvoda u odnosu na dužinu ugljovodoničnog lanca, razvoj detaljnog kinetičkog modela FTS (sposobnog da ujedno predskaže brzine nestajanja reaktanata i nastajanja proizvoda) i primena detaljnog kinetičkog modela u modelovanju i optimizaciji višecevnih FTS reaktora sa pakovanim slojem katalizatora. Najčešće korišćeni katalizatori za FTS su gvožđe i kobalt. Eksperimentalni podaci za gvozdeni i kobaltni katalizator korišćeni u ovoj studiji su dobijeni u saradnji sa Texas A&M Univerzitetom (Texas A&M University) i Centrom za primenjeno istrazivanje energije Univerziteta u Kentakiju (Center for Applied Energy Research, University of Kentucky), respektivno. Analiza eksperimentalnih podataka za oba katalizatora je pokazala zavisnost selektivnosti proizvoda reakcije of procesnih uslova unutar reaktora (temperature, pritiska, odnosa reaktanata u ulaznoj smeši i konverzije reaktanata). Pokazano je da su ove zavisnosti povezane sa verovatnoćom rasta ugljovodoničnog lanca (α), koja se takođe menja sa brojem atoma ugljenika. Značajne varijacije u vrednosti verovatnoće rasta C1 lančanih intermedijera pri različitim procesnim uslovima, zabeležene sa kobaltnim katalizatorom, kao i odsustvo istih varijacija za duže C2+ lančane intermedijere, su interpretirane kao dokaz postojanja dodatnog reakcionog puta za metanaciju. Isti rezultati su poslužili kao dokaz da sekundarne reakcije 1-alkena ne igraju bitnu ulogu u određivanju selektivnosti FTS. Slične korelacije između promena verovatnoće rasta lanca i procesnih uslova su zapažene i sa gvozdenim katalizatorom. Međutim, postojanje dodatnog reakcionog puta za formiranje metana i važnost sekundarnih reakcija alkena nisu potvrđene za taj katalzator...
PB  - Univerzitet u Beogradu, Tehnološko-metalurški fakultet
T1  - Kinetic modeling and oprimization of fixed-bed reactor for Fischer-Tropsch synthesis
UR  - https://hdl.handle.net/21.15107/rcub_technorep_4622
ER  - 

@phdthesis{
author = "Todić, Branislav",
year = "2015",
abstract = "Fischer-Tropsch synthesis (FTS) is a heterogeneously catalyzed chemical reaction in which a mixture of hydrogen and carbon-monoxide is converted into an array of hydrocarbon products. These products can be used as synthetic liquid fuels (gasoline, diesel, kerosene) or feedstock for the chemical industry. As such, FTS is a key step in the conversion of coal, natural gas and biomass into liquids in large plants all over the world, including plants in Qatar, Malaysia, South Africa etc. Even though FTS has been commercially used for most of the 20th century, many fundamental aspects of this reaction are unclear. The main objectives of the work included in this thesis were: to study the effect of process conditions on FTS product selectivity and distribution with regards to hydrocarbon chain length, develop a detailed model of FTS kinetics (capable of predicting both reactant disappearance and product formation rates) and apply the detailed kinetic model in modeling and optimization of a multi-tubular fixed-bed reactor for FTS. Most often used catalysts for FTS are iron and cobalt. The experimental data used in this study were obtained in collaboration with Texas A&M University and Center for Applied Energy Research, University of Kentucky, for iron- and cobalt-based catalyst, respectively. The analysis of experimental data for both catalysts showed dependence of product selectivity from process conditions inside the reactor (temperature, pressure, reactant feed ratio and conversion level). These dependences were shown to be related to the chain-growth probability factor (α), which also varies with carbon number. Over the cobalt catalyst, the significant variation of C1 intermediate growth probability (α1) at different process conditions and a lack of the same variations for higher C2+ chain intermediates, was interpreted as evidence for the existence of separate methanation pathways. The same data presented evidence that the secondary 1-olefin readsorption does not play a major part in determining FTS selectivity. For the iron-based catalysts, similar correlations between variations of growth probability with process conditions were found. However, existence of additional pathways for methane formation and relevance of secondary olefin reactions could not be confirmed for that catalyst..., Fischer-Tropsch sinteza (FTS) je heterogeno katalizovana hemijska reakcija u kojoj se smeša vodonika i ugljen-monoksida pretvara u niz ugljovodoničnih proizvoda. Ti proizvodi se mogu koristiti kao sintetička tečna goriva (benzin, dizel i kerozin) ili sirovine za hemijsku industriju. Kao takva, FTS je ključni korak u konverziji uglja, prirodnog gasa i biomase u tečnosti u velikim postrojenjima širom sveta, uključujući postrojenja u Kataru, Maleziji, Južnoj Africi itd. Iako je FTS veći deo dvadesetog veka bila u komercijalnoj upotrebi, mnogi fundamentalni aspekti ove reakcije su nejasni. Glavni ciljevi istraživačkog rada u sklopu ove disertacije su bili: ispitivanje efekata procesnih uslova na selektivnost i raspodelu FTS proizvoda u odnosu na dužinu ugljovodoničnog lanca, razvoj detaljnog kinetičkog modela FTS (sposobnog da ujedno predskaže brzine nestajanja reaktanata i nastajanja proizvoda) i primena detaljnog kinetičkog modela u modelovanju i optimizaciji višecevnih FTS reaktora sa pakovanim slojem katalizatora. Najčešće korišćeni katalizatori za FTS su gvožđe i kobalt. Eksperimentalni podaci za gvozdeni i kobaltni katalizator korišćeni u ovoj studiji su dobijeni u saradnji sa Texas A&M Univerzitetom (Texas A&M University) i Centrom za primenjeno istrazivanje energije Univerziteta u Kentakiju (Center for Applied Energy Research, University of Kentucky), respektivno. Analiza eksperimentalnih podataka za oba katalizatora je pokazala zavisnost selektivnosti proizvoda reakcije of procesnih uslova unutar reaktora (temperature, pritiska, odnosa reaktanata u ulaznoj smeši i konverzije reaktanata). Pokazano je da su ove zavisnosti povezane sa verovatnoćom rasta ugljovodoničnog lanca (α), koja se takođe menja sa brojem atoma ugljenika. Značajne varijacije u vrednosti verovatnoće rasta C1 lančanih intermedijera pri različitim procesnim uslovima, zabeležene sa kobaltnim katalizatorom, kao i odsustvo istih varijacija za duže C2+ lančane intermedijere, su interpretirane kao dokaz postojanja dodatnog reakcionog puta za metanaciju. Isti rezultati su poslužili kao dokaz da sekundarne reakcije 1-alkena ne igraju bitnu ulogu u određivanju selektivnosti FTS. Slične korelacije između promena verovatnoće rasta lanca i procesnih uslova su zapažene i sa gvozdenim katalizatorom. Međutim, postojanje dodatnog reakcionog puta za formiranje metana i važnost sekundarnih reakcija alkena nisu potvrđene za taj katalzator...",
publisher = "Univerzitet u Beogradu, Tehnološko-metalurški fakultet",
title = "Kinetic modeling and oprimization of fixed-bed reactor for Fischer-Tropsch synthesis",
url = "https://hdl.handle.net/21.15107/rcub_technorep_4622"
}

Todić, B.. (2015). Kinetic modeling and oprimization of fixed-bed reactor for Fischer-Tropsch synthesis. 
Univerzitet u Beogradu, Tehnološko-metalurški fakultet..
https://hdl.handle.net/21.15107/rcub_technorep_4622

Todić B. Kinetic modeling and oprimization of fixed-bed reactor for Fischer-Tropsch synthesis. 2015;.
https://hdl.handle.net/21.15107/rcub_technorep_4622 .

Todić, Branislav, "Kinetic modeling and oprimization of fixed-bed reactor for Fischer-Tropsch synthesis" (2015),
https://hdl.handle.net/21.15107/rcub_technorep_4622 .

TY  - JOUR
AU  - Todić, Branislav
AU  - Ma, Wenping
AU  - Jacobs, Gary
AU  - Davis, Burtron
AU  - Bukur, Dragomir B.
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3107
PB  - Amer Chemical Soc, Washington
T2  - Abstracts of Papers of the American Chemical Society
T1  - Importance of methane formation in determining overall selectivity of Fischer-Tropsch synthesis over cobalt-based catalyst
VL  - 249
UR  - https://hdl.handle.net/21.15107/rcub_technorep_3107
ER  - 

@article{
author = "Todić, Branislav and Ma, Wenping and Jacobs, Gary and Davis, Burtron and Bukur, Dragomir B.",
year = "2015",
publisher = "Amer Chemical Soc, Washington",
journal = "Abstracts of Papers of the American Chemical Society",
title = "Importance of methane formation in determining overall selectivity of Fischer-Tropsch synthesis over cobalt-based catalyst",
volume = "249",
url = "https://hdl.handle.net/21.15107/rcub_technorep_3107"
}

Todić, B., Ma, W., Jacobs, G., Davis, B.,& Bukur, D. B.. (2015). Importance of methane formation in determining overall selectivity of Fischer-Tropsch synthesis over cobalt-based catalyst. in Abstracts of Papers of the American Chemical Society
Amer Chemical Soc, Washington., 249.
https://hdl.handle.net/21.15107/rcub_technorep_3107

Todić B, Ma W, Jacobs G, Davis B, Bukur DB. Importance of methane formation in determining overall selectivity of Fischer-Tropsch synthesis over cobalt-based catalyst. in Abstracts of Papers of the American Chemical Society. 2015;249.
https://hdl.handle.net/21.15107/rcub_technorep_3107 .

Todić, Branislav, Ma, Wenping, Jacobs, Gary, Davis, Burtron, Bukur, Dragomir B., "Importance of methane formation in determining overall selectivity of Fischer-Tropsch synthesis over cobalt-based catalyst" in Abstracts of Papers of the American Chemical Society, 249 (2015),
https://hdl.handle.net/21.15107/rcub_technorep_3107 .

TY  - JOUR
AU  - Todić, Branislav
AU  - Olewski, Tomasz
AU  - Nikačević, Nikola
AU  - Bukur, Dragomir B.
PY  - 2013
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2453
AB  - The kinetic models of Fischer-Tropsch synthesis (FTS) product distribution can be classified into two major groups: hydrocarbon selectivity models and detailed Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic models. In this study the two approaches to FTS product distribution modeling are presented and compared using the experimental data obtained in a stirred tank slurry reactor with promoted iron catalyst over a wide range of process conditions. Positive deviations from the classical Anderson-Schulz-Flory distribution and an exponential decrease in olefin-to-paraffin ratio with carbon number are predicted by the inclusion of solubility-enhanced 1-olefin readsorption and/or chain length dependent 1-olefin desorption concepts. In general the agreement between the model predictions and experimental data was very good, and modeling approaches are discussed in terms of fit quality, physical meaningfulness and practical utility.
PB  - Aidic Servizi Srl, Milano
T2  - ICHEAP-11: 11th International Conference on Chemical and Process Engineering, Pts 1-4
T1  - Modeling of Fischer-Tropsch Product Distribution over Fe-based Catalyst
EP  - 798
SP  - 793
VL  - 32
DO  - 10.3303/CET1332133
ER  - 

@article{
author = "Todić, Branislav and Olewski, Tomasz and Nikačević, Nikola and Bukur, Dragomir B.",
year = "2013",
abstract = "The kinetic models of Fischer-Tropsch synthesis (FTS) product distribution can be classified into two major groups: hydrocarbon selectivity models and detailed Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic models. In this study the two approaches to FTS product distribution modeling are presented and compared using the experimental data obtained in a stirred tank slurry reactor with promoted iron catalyst over a wide range of process conditions. Positive deviations from the classical Anderson-Schulz-Flory distribution and an exponential decrease in olefin-to-paraffin ratio with carbon number are predicted by the inclusion of solubility-enhanced 1-olefin readsorption and/or chain length dependent 1-olefin desorption concepts. In general the agreement between the model predictions and experimental data was very good, and modeling approaches are discussed in terms of fit quality, physical meaningfulness and practical utility.",
publisher = "Aidic Servizi Srl, Milano",
journal = "ICHEAP-11: 11th International Conference on Chemical and Process Engineering, Pts 1-4",
title = "Modeling of Fischer-Tropsch Product Distribution over Fe-based Catalyst",
pages = "798-793",
volume = "32",
doi = "10.3303/CET1332133"
}

Todić, B., Olewski, T., Nikačević, N.,& Bukur, D. B.. (2013). Modeling of Fischer-Tropsch Product Distribution over Fe-based Catalyst. in ICHEAP-11: 11th International Conference on Chemical and Process Engineering, Pts 1-4
Aidic Servizi Srl, Milano., 32, 793-798.
https://doi.org/10.3303/CET1332133

Todić B, Olewski T, Nikačević N, Bukur DB. Modeling of Fischer-Tropsch Product Distribution over Fe-based Catalyst. in ICHEAP-11: 11th International Conference on Chemical and Process Engineering, Pts 1-4. 2013;32:793-798.
doi:10.3303/CET1332133 .

Todić, Branislav, Olewski, Tomasz, Nikačević, Nikola, Bukur, Dragomir B., "Modeling of Fischer-Tropsch Product Distribution over Fe-based Catalyst" in ICHEAP-11: 11th International Conference on Chemical and Process Engineering, Pts 1-4, 32 (2013):793-798,
https://doi.org/10.3303/CET1332133 . .