Isobutane/2-Butene Alkylation Reaction Catalyzed by Cu-Modified and Rare Earth X-Type Zeolite

Different metal compositions based on metal-ion-modified X-type zeolite in the isobutane/2-butene alkylation reaction were investigated. Bimetallic (rare earth (RE) and Cu) supported zeolites catalysts owned better lifetime and selectivity than those modified by the single metal (La, Ce, or Cu). CuLaX performed best with a 15 h catalytic lifetime obtained after hydrogen activation when the content of copper was 0.197 mmol/g. The possible reason is that the RE X-type catalyst modified with copper ion increases the concentration of strong Brønsted acid sites, which is more favorable for the hydride transfer in the alkylation. Herein, the valence of copper ions is of importance to the alkylation performance. A mechanism was proposed wherein the existence of Cu+ inhibited the progress of the oligomerization reaction and then prolonged the lifetime of the catalyst through decreasing the desorption concentration of 2-butene in the active site.