CoMo Sulfide Catalysts Supported on Natural Halloysite Nanotubes: Dealumination as an Effective Approach to Improve Catalytic Performance

Abstract

–CoMo sulfide catalysts supported on aluminosilicate halloysite nanotubes (CoMoS/HNT) and on dealuminated halloysite nanotubes (CoMoS/HNT(deAl)) were synthesized by incipient wetness impregnation using pseudoboehmite as a binder. Both the supports and related catalysts were characterized by low-temperature nitrogen adsorption, energy dispersive X-ray fluorescence analysis, temperature-programmed reduction by hydrogen, FTIR spectroscopy of adsorbed pyridine, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalyst samples were further tested in hydrotreating of diesel feedstocks. Dealumination of halloysite was found to increase the area of Si-enriched surface segments, thus weakening interaction between the sulfide phase and the support and, hence, increasing the content of highly active sulfide particles. In the case of a mixed feedstock, CoMoS/HNT(deAl) + Al₂O₃ achieved a reaction rate constant of 0.605 ppm S^–0.4/g(L^–0.4 h) compared to 0.429 ppm S^–0.4/g(L^–0.4 h) for an alumina-supported sample.