Cracking of naphtha range alkanes and naphthenes over zeolites

摘要

Naphtha range alkanes and naphthenes can be activated over H-form of zeolites, which provide low temperature cracking pathways that are otherwise unavailable during conventional steam cracking. A range of zeolitic catalysts were tested for cracking naphtha. Due to their relatively larger kinetic diameter, isoalkanes and naphthenes exhibited lower reactivity than linear alkanes over 8-MR zeolites. 12-MR zeolites favored bimolecular hydride transfer pathways, which eventually increased the selectivity to light alkanes and to coke at the expense of ethylene and propylene. Hydride transfer and aromatization were suppressed by keeping the number of acid sites low. Primary reaction products n-butenes-butane showed low reactivity for secondary conversion over 12-MR zeolites, but showed relatively high reactivity over 10-MR zeolites. The highest ethylene and propylene yields were obtained over 10-MR zeolites such as Ferrierite.