1-hexene isomerization over bimetallic M-Mo-ZSM-5 (M: Fe, Co, Ni) zeolite catalysts: Effects of transition metals addition on the catalytic performance

The aim of this study is to investigate the promotional effect of Fe-Mo, Co-Mo, and Ni-Mo bimetallic additives on the activity and stability of H-ZSM-5 zeolite for isomerization of 1-hexene. The catalysts were synthesized by wet-impregnation method and characterized by XRD, FTIR, BET, ICP-AES, HRSEM-EDS, HRTEM, H-2-TPR, NH3-TPD, and pyridine-DRIFT analysis. The isomerization of 1-hexene was carried out in a micro-scale system under the conditions: T = 250 degrees C, P = 4.0 MPa, FR = 0.1 ml/min, WHSV = 1 h(-1). The conversion of 1-hexene over the 4 g bed of catalyst was in the range of 95-97% after 74 h time-on-stream with cis-3-hexene and cis-2-hexene as the principal products. It was shown that the appearance of the new strong Lewis acid sites, decreases the ratio of Bronsted/Lewis acid sites. Increase of the weak Lewis acid sites in the 2.5 wt%Ni2.5 wt%Mo-ZSM-5 catalyst facilitated the isomerization of 1-hexene and showed higher C6 olefin selectivity (48.4 mol%), research octane number (99.7), and bromine number (148.3) than other studied catalysts. (C) 2019 Energy Institute. Published by Elsevier Ltd. All rights reserved.