The critical role of solvent polarity in the preparation of tube-like Co–Mo sulfide catalysts for the hydrodeoxygenation of stearic acid

Abstract

Co–Mo sulfides with tube-like structures were prepared through a low-temperature pre-sulfurization process using rod-like CoMoO₄ as the precursor. Pre-sulfurization solvents with different polarities markedly affected the textural properties, the concentration and microstructure of the active components, and the catalytic deoxygenation activity. The increased solvent polarity can promote the formation of hollow structures and the degree of sulfurization of the precursor, and the appropriate polarity of pre-sulfurization solvents is helpful for the sulfurization of CoMoO₄ to form (Co)MoS₂ slabs with shorter lengths and greater stacking numbers, which means more coordinatively unsaturated sites, especially corner sites. The results of the hydrodeoxygenation reaction of stearic acid suggested that a higher f_c/f_e resulted in a greater reaction rate of stearic acid, and the yields of the liquid products were highly dependent on the number of surface-active sites, which mainly originated from type II CoMoS species. Moreover, increasing the reaction temperature favored the direct hydrodeoxygenation pathway.