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