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, H2-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 °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 Brönsted/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.