Effect of metal–support interaction on the catalytic performance of Ni/Al 2O 3 for selective hydrogenation of isoprene

Abstract

The effect of the interaction between metal and support on the performance of different phases alumina supported nickel catalysts was demonstrated in liquid phase selective hydrogenation of isoprene in simulated gasoline. Catalysts supported on γ-Al 2O 3 and κ-Al 2O 3 were characterized by BET, XRD, TPR, and XPS techniques. The results showed that a “surface spinel”, NiAl 2O 4 was formed. The supported nickel ions preferentially incorporate into the tetrahedral vacancies of γ-Al 2O 3 support to form SMSI (strong metal–support interaction), while WMSI (weak metal–support interaction) was formed on κ-Al 2O 3 support with little tetrahedral vacancy. When there were enough hydrogenation sites, the Ni/γ-Al 2O 3 catalysts with SMSI which can resist carbon deposition, performed higher isoprene conversion, higher stability and lower selectivity than the same nickel loading Ni/κ-Al 2O 3 samples with WMSI. The weak interaction had a positive effect on the formation of coke, which was mainly related to the hydrogenolytic sites, leading to main reaction with high mono-olefins selectivity with isoprene conversion decrease evidently.