2016 Volume 59 Issue 5 Pages 184-196
Zeolite-containing catalysts with hierarchical structures were prepared by combining microporous zeolites (beta and Y zeolite) with mesoporous matrices (silicas and silica–aluminas with large mesopores) prepared by the gel skeletal reinforcement method and a binder. Morphology of the prepared catalysts was characterized by X-ray diffraction, nitrogen adsorption-desorption, ammonia adsorption-desorption, and thermogravimetric-differential thermal analysis. Catalytic cracking of soybean oil was performed with these mixed catalysts to observe the effect of the pore size on the catalytic activity and the selectivity of products using the convenient Curie point pyrolyzer. Zeolite-containing mixed catalysts exhibited great improvements in all aspects such as maximum increase of 31 % conversion, about 10 % higher gasoline yields, and maximum decrease of 36 % coke formation in comparison with single zeolite, indicating that the presence of the matrices greatly influenced the catalytic cracking. The yields of gasoline, single branched and multi-branched hydrocarbons increased with higher conversion, indicating that increased conversion was necessary to obtain higher yields of products. In comparison of product yields at the same conversion, Y zeolite-containing catalysts exhibited the higher yields than beta (β) zeolite-containing catalysts, indicating that the larger micropore diameter of Y zeolite in the catalysts induced the increase in the gasoline fraction and promoted the isomerization to produce the bulkier products. The conversion of soybean oil increased with increasing the pore diameter for β series catalysts and the conversions were maximum for MAT(200S)-β and MAT(200SA)-β with relatively larger mesopores, indicating that the diffusion of reactants and products affected the catalytic performance. In contrast to this phenomenon, MAT(0S)-Y and MAT(0SA)-Y with relatively smaller mesopores exhibited the maximum conversions for Y series catalysts.
