摘要
To systematically study the conversion process of paraffin,cycloalkane,and aromatic on ZSM-5 molecular sieve in naphtha hydrocracking,a series of related experiments were carried out based on the prepared hydrocracking catalyst,Catalyst-HC.Ni and ZSM-5 molecular sieve were selected as the hydrogenation active component and the cracking component of Catalyst-HC,respectively.The results obtained through this work indicate that on ZSM-5 molecular sieve,the paraffin and cycloalkane in naphtha are mainly convertible hydrocarbons.The higher the content of convertible hydrocarbons in naphtha,the easier it is for the conversion reaction to occur.As C_(5+)conversion rate rises,the yields of paraffin and cycloalkane decline,and the yields of aromatic and aromaticcarbon in product-naphtha remain almost unchanged.The aromatic-average carbon-number(CN)in productnaphtha changes very little,decreasing from 8.3 to 8.2.This means that almost no aromatic undergoes the saturation reaction or conversion reaction on Catalyst-HC.Due to the small pore size of ZSM-5,C_(5+)i-paraffin has a lower conversion rate and a higher average CN compared to C_(5+)n-paraffin.Meanwhile,as C_(5+)conversion rate gradually rises from 0 to 23%,the average CN drop-values of C_(5+)n-paraffin and C_(5+)i-paraffin are 1.3 and 0.14,respectively.C_(5)-ring cycloalkane-ring-carbon(C_(5)-ring CRC)is more likely undergoing ring-opening(RO)reaction than that of C6-ring cycloalkane-ring-carbon(C6-ring CRC).The conversion rate of C_(5)-C_(7)cycloalkane is higher than that of C8+cycloalkane,and the former bears a higher jump-value compared to the latter with the increase of C_(5+)conversion rate.Unlike paraffin and aromatic,the average CN of cycloalkane gradually rises with the increase of C_(5+)conversion rate.
基金
supported by SINOPEC Research Programs(Grant KL20009 and 121028-2).
