THE CRACKING REACTION-PATH IN 1-HEXENE ISOMERIZATION ON SAPO-11 AND PD/SAPO-11

In order to investigate into the predominant cracking pathway on SAPO-11, the activity and selectivity patterns for 1-hexene isomerization have been compared in the temperature range of 150-450-degrees-C for four different kinds of acidic molecular sieves(H-mordenite, HZSM-5, SAPO-11 and Pd/SAPO-11). The predominant reaction pathway was double bond shift(DBS) at lower temperature (around 150-degrees-C) without regarding the type of catalyst. However, at higher temperature significant, shifts in selectivity were observed from DBS to cracking(C) or skeletal rearrangement(SR) depending on the type of catalyst. The cracking reaction path was considered two ways. One is dimerization between linear hexenes and the other is dimerization between linear hexene and SR isomers. Two paths were almost equated on SAPO-11, but latter path was predominant on Pd impregnated SAPO-11, HZSM-5 followed the former cracking path because of its characteristic small pores and complex pore structure. In the comparison between the reaction path and the acidity of catalyst, the lager the acidity of catalyst the more dominant the former path.