Methanolysis of sunflower oil using alumina/silica supported potassium oxide (K2O) as a heterogeneous catalyst

Abstract

Biodiesel, the most promising alternative to diesel fuel, is renewable, biodegradable, environmentally friendly and can be used in existing engines. Certain disadvantages of conventional processes of biodiesel, i.e. fatty acid methyl esters (FAME) synthesis could be avoided by applying new technologies which are based on using heterogeneous catalyst under moderate and high temperatures and pressures. Heterogeneous catalyst is easily removed from the products of reaction, making purification and neutralization process much simpler. Beside the fact that synthesis becomes less problematic for environment, it can also improve the economics of biodiesel production and lead to cheaper production costs. In this study a new type of heterogeneous catalyst with K2O as active component on alumina/silica support is synthesized. A starting step when producing catalyst (aerogel and xerogel) is a sol-gel synthesis, method that provides a possibility to add different catalyst constituents in only one step. It is followed by drying of the wet gel: drying at elevated temperature and atmospheric pressure to obtain xerogel and supercritical drying with supercritical carbon dioxide to obtain aerogel. Prepared catalysts were used in the methanolysis of sunflower oil at 200˚C and 37 bar with molar ratio methanol:oil 30:1 and 2 wt% of catalyst (based on oil). For the catalysts that showed better activity the possibility to optimize the process of FAME synthesis was investigated. The efficiency of process under different temperatures (80-200°C), reaction times (15min-8h) and molar ratios of methanol to oil (6:1-30:1) was analyzed. With the yield of FAME over 93% after 15 minutes, some catalysts showed very good activity and are promising catalysts for FAME synthesis. .

Određeni nedostaci konvencionalnih načina sinteze biodizela, tj. metil estara masnih kiselina (MEMK) mogu se izbeći primenom novih tehnologija koje se baziraju na korišćenju heterogenih katalizatora. U ovom radu novi tip heterogenog katalizatora sa K2O kao aktivnom komponentom na alumosilikatnom nosaču je sintetizovan sol-gel postupkom. Dobijeni katalizatori korišćeni su u reakciji metanolize suncokretovog ulja. Ispitana je efikasnost procesa pri različitim temperaturama (80-200°C), vremenu trajanja reakcije (15min-8h) i molarnom odnosu metanol:ulje (6:1-30:1). Sa prinosom MEMK od preko 93% za 15 minuta, pojedini katalizatori pokazali su se kao veoma aktivni i efikasni katalizatori za proces sinteze MEMK. .