The application of the zeolyte powder for the construction of the dense composite membranes for the carbon-dioxide separation

Abstract

The main task of the work is to construct the polymeric membrane that could be used for the waste gases treatment. For this purpose, membrane must have high permeability for the carbon dioxide and low permeability of the other gases commonly present in waste gases (hydrogen, oxygen, nitrogen and methane). The constructed membranes were of a dense type, based on a solubility/diffusivity mechanism. In order to enchase the permeability of carbon dioxide, four different zeolytes were added, and in order to improve mechanical stability two different additives were tested. Three zeolytes were with the 3-dimensional pores (ZSM5; Faujasite Linde type A) and one was with the 1-dimensional pores (Linde type L). As an additive, n-tetradecyldimethylamonium bromide - n-C14TMABr was tested. The aim of an additive was to provide good wetting of a highly electrically charged zeolyte particle by the hydrophobic polymer chains. The other examined additive was dimethylaminopyridine (DMAP) which should improve the solubility of carbon dioxide due to its alkali properties. The best results in carbon dioxide/hydrogen selectivity and permeability were obtained with the membrane constructed with PEBAX 1657 and surface treated zeolyte. The obtained permeability of carbon dioxide was 128 Barrer, and the carbon dioxide/hydrogen selectivity was 9.7.

Cilj istraživanja prikazanih u ovom radu je izrada polimerne membrane koja bi imala primenu u prečišćavanju otpadnih gasova. Membrana konstruisana za ovu primenu bi morala da ima visoku permeabilnost za ugljen-dioksid i nisku permeabilnost za druge gasove koji su standardno prisutni u otpadnim gasovima (vodonik, kiseonik, azot i metan). Dobijene membrane pripadaju tipu neporoznih membrana čija se permeabilnost bazira na mehanizmu rastvaranja i difuzije. U ovom radu, ispitivana je mogućnost primene poli(etilenoksida) - kopoli(ftalamida) za ovu svrhu. Da bi se povećala permeabilnost ugljen-dioksida, dodate su četiri različite vrste zeolitnih prahova, a u cilju poboljšanja mehaničkih svojstava, ispitivana su dva aditiva. Tri zeolitna praha korišćena u eksperimentu imaju trodimenzionalne pore (ZSM5, Faujasit i Linde zeolit tip A), a jedan prah je sa jednodimenzionalnim porama (Linde zeolit tip L). Kao aditiv je testiran n-tetradeciltrimetilamonijum bromid. Cilj dodavanja ovog aditiva je da omogući dobar kontakt između dugih, hidrofobnih polimernih lanaca i naelektrisanih čestica zeolita. Drugi ispitivani aditiv je dimetilaminopiridin, čija bi bazna svojstva trebalo da poboljšaju rastvorljovost ugljen dioksida. Najbolji rezultati su postignuti korišćenjem membrane konstruisane sa PEBAX 1657 polimerom i zeolitom u prisustvu aditiva.