Skeletal isomerization of 1-butene into isobutene over Mg-ZSM-22 modified by the deposition of silicon alkoxide

Mg-ZSM-22, modified by the deposition of silicon ethoxide, was prepared and investigated as a catalyst for the skeletal isomerization of 1-butene to isobutene in a fixed-bed flow reactor. The prepared catalysts were characterized by XRD, TPD, SEM-EDX, ICP and FT-IR.; The deposition of silicon alkoxide on Mg-ZSM-22 led to a decrease in the amount of strong acid sites, confirmed by TPD experiments with ammonia and gamma-collidine. The treatment also affected the size of pore opening, as evidenced by constraint index measurement and chemisorption experiment using n-hexane. As the deposition time increased, the conversion of 1-butene decreased as the result of reduced acidity, while selectivity to isobutene increased. The deposition of silicon alkoxide resulted in the suppression of side reactions and coke deposition, thus enhancing the skeletal isomerization. The modification of Mg-ZSM-22 by deposition of silicon alkoxide was very effective in terms of catalytic stability and coke removal.