Ni/γ-Al2O3 catalyzed hydrogenation of mixed long chain α-olefin
Ni/γ-Al2O3(DI)and Ni/γ-Al2O3(CEDI)with different Ni loading(theoretical value,based on the mass of support,the same below)were prepared by dry impregnation method(DI)and charge-enhanced dry impregnation method(CEDI)using γ-Al2O3 as support,and characterized by SEM,TEM,BET and XPS.The influence of relationship between catalyst pore size and mixed olefin particle size on the catalytic activity of the catalysts was analyzed,with their performance in hydrogenation reaction further evaluated.The results showed that the average pore size of Ni/γ-Al2O3(DI)and Ni/γ-Al2O3(CEDI)was larger than the width of the average particle size of mixed olefins(2.17 nm),which reduced the impact of internal diffusion,thereby enhancing catalytic activity.Under the conditions of 120 ℃ and 3 MPa,15Ni/γ-Al2O3(DI)with 15％Ni loading exhibited catalytic efficiency for octadecene and mixed olefins of 9666.1 and 6580.9 mol/(g·h),respectively,while 20Ni/γ-Al2O3(CEDI)with 20％Ni loading showing 19591.3 and 14537.8 mol/(g·h)respectively,even higher.This was mainly attributed to the fact that CEDI adjusted the acidity and basicity of the γ-Al2O3 surface and used the charge enhancement effect to regulate the interaction between Ni andγ-Al2O3,making Ni more uniformly dispersed on the support,reducing the size of Ni particles,and optimizing the dispersion and stability of the active components.
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