Hydrocracking of Fischer–Tropsch Paraffin Mixtures over Strong Acid Bifunctional Catalysts to Engine Fuels

摘要

Biomass-based Fischer–Tropsch paraffin mixtures, having C_(16)–C_(46) and C_(11)–C_(45) carbon number range, were hydrocracked over platinum-supported beta, ZSM-5, and mordenite catalysts. The aim of the study was to investigate the effects of the feedstock composition, the process parameters, and the catalyst properties (acidity and zeolite structure) on the C_(21~(+)) conversions, the product yields, and the isoparaffin contents. It was stated that lower C_(21~(+)) conversions and higher JET and diesel fuel yields can be obtained for feedstock comprising C_(11)–C_(45) hydrocarbons. Under identical reaction conditions, the activity order of the catalysts was Pt/H-beta > Pt/H-ZSM-5 > Pt/H-mordenite. This order corresponds to the relative number of accessible acid sites. Among the tested catalysts, platinum-supported beta zeolite showed the highest hydroisomerization activity; meanwhile, in the pores of Pt/ZSM-5 and Pt/H-mordenite, diffusion constraints were observed. As the product of hydrocracking valuable gasoline, JET and diesel fuels having high hydrogen content and excellent burning properties were produced.