The catalytic effect of boron substituted ZSM-5 and MCM-41 molecular sieves on 1-octene isomerization

A series of B-MCM-41 and B-ZSM-5 samples has been synthesized from gel mix containing the SiO2/B2O3 ratio of 20, 50, 100 and 200. Ethylsilicate ester (ES-40) used as the silica source in these syntheses and materials were characterized by XRD, FTIR, BET, SEM, pyridine adsorption, temperature programmed desorption of ammonia and chemical analysis. The B substitution in MCM-41 and ZSM-5 framework results only weak Lewis and Bronsted acid sites. The isomerization of 1-octene was found to be influenced by the boron content in the framework. The selectivity of 2-octene and 3-octene was found to decrease with a simultaneous increase in the selectivity of 4-octene, methylheptenes and dimethylhexenes with the decrease in SiO2/B2O3 ratio of catalysts and an increase in temperature of reaction. The 1-octene isomerization on B-MCM-41 and B-ZSM-5 leads to both hydrogen shift and skeletal rearrangement. Lower selectivity of skeletal isomerization products was observed with B-MCM-41 catalysts compared to that with B-ZSM-5 catalysts. The mesopores of B-MCM-41 catalysts suffer slightly higher coking and aging than B-ZSM-5 catalysts (C) 2003 Elsevier Inc. All rights reserved.