Preparation of Cu/ZnO/Al2 O3 catalyst based on ZnAl-layered double hydroxide precursor for gas-phase aldehyde hydrogenation
Three different Cu/ZnO/Al2 O3 catalysts based on ZnAl-LDH precursors were prepared using sodium meta-alumi-nate as the aluminum source through one-step,two-step,and mixed methods.The structural properties of the catalysts and their precursors were characterized.Combined with the catalytic results for octenal(2-ethyl-2-hexenal,EPA)hydrogenation reaction,the effects of different preparation methods and aluminum introduction methods on the formation of ZnAl2 O4 spinel were investigated,and the structure-activity relationship between the structure of the obtained catalysts and their catalytic performance under different conditions was studied.Results show that the catalyst obtained by the mixed method exhibites comparable activity to industrial catalysts in the gas-phase hydrogenation of octenal.The product selectivity is 1.9%and 2.5%higher than that of industrial catalyst at a space velocity of 1.5 and 4.0 h-1,respectively.This is mainly because the ZnAl-LDH precursor prepared with sodium meta-aluminate as the aluminum source greatly improves the zinc aluminum bind-ing efficiency,reduces the production of unbound Al2 O3,improves product selectivity,and achieves the transformation of ZnAl-LDH to ZnAl2 O4 spinel under low calcination temperature(380℃),which avoides the sintering of CuO in traditional high-temperature calcination processes.
Cu/ZnO/Al2 O3 catalystZnAl2 O4 spinelZnAl-layered double hydroxidehydrogenation of gaseous aldehyde
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