Cascade hydrogenation of n-C16 to produce jet fuel over tandem catalysts of modified ZSM-22

Abstract

ZSM-22 with one-dimensional straight channels and suitable acid properties is widely applied in the selective hydrocracking of long-chain alkanes to produce middle distillate. In this work, the tandem catalysts with two kinds of modified ZSM-22 were employed in series to optimize the distribution of the product in the hydrotreatment of n-C16 to produce jet fuel. The yield of linear alkanes with high carbon numbers was enhanced over the upstream catalyst bed of Pt/L-HZSM-22 with shielded external acid sites while the isomerization with less further cracking occurred over the downstream catalyst bed of Pt/Me-HZSM-22 with introduced mesopores. The tandem catalysts can combine the ability of Pt/L-HZSM-22 to produce heavy n-alkanes and the stronger isomerization performance of Pt/Me-HZSM-22. The highest yield of jet fuel (∼23 wt.%) can be obtained over the tandem catalysts instead of any individual catalyst. The strategy of the tandem zeolite has been initially verified and proposed to broaden the investigation perspectives of the oil refinery.