Hydroisomerization of 1-octene utilizing hierarchical SAPO-11-supported Ni catalysts: effect of the alkyl chain length of the mesoporogen

Abstract

A series of hierarchical SAPO-11 molecular sieves synthesized by adding mesoporogens with different alkyl chain lengths were prepared. The synthesized hierarchical SAPO-11s were characterized by XRD, SEM, N₂ adsorption–desorption, TEM, NH₃-TPD and Py-IR. The results showed that the physicochemical properties of the hierarchical SAPO-11s change with the increase of the alkyl chain length, and the hierarchical SAPO-11 molecular sieve synthesized with DTAB has the largest external surface area and pore volume, and the most medium and strong B acid sites. Furthermore, the 1-octene hydroisomerization reaction on Ni catalysts supported on hierarchical SAPO-11 was investigated and the experimental results showed that the alkyl chain length of the mesoporogen has an obvious influence on the hydroisomerization selectivity. The hierarchical Ni/SAPO-11 catalyst synthesized using DTAB has the highest selectivity of C₈ isomers and the lowest cracking selectivity. These results indicate that DTAB is the most suitable mesoporogen for the synthesis of hierarchical SAPO-11 molecular sieves for 1-octene hydroisomerization.