Effect of Thermal Treatment on Hydrogen Uptake and Characteristics of Ni-, Co-, and Mo-Containing Catalysts

Nonsulfided alumina supported Ni, Co, Mo, NiMo, and CoMo hydrotreating catalysts were synthesized. The TEM results indicated low dispersions of the active metals for Mo, NiMo, and CoMo samples but significantly higher dispersion for the Ni sample. The effect of calcination and reduction on the hydrogen uptake capacity of the samples was investigated. The H2-chemisorption and XPS results together showed that the precalcination step had a detrimental effect on the hydrogen adsorption of the Ni sample formation of stable metal oxides. The XPS results revealed that the metal oxides of all calcined samples reacted with the alumina support to form very stable spinels. Further, the positive effects of a hydrogen atmosphere, during the reduction, on the hydrogen uptake of the samples were confirmed by H2-chemisorption measurements. Finally, the heats of adsorption (ΔH) of hydrogen for the Ni and Co samples were calculated to be 140 and 98 kJ mol–1, respectively.