Temperature sensitive synthesis of γ-Al2O3 support with different morphologies for CoMo/γ-Al2O3 catalysts for hydrodesulfurization of thiophene and 4,6-dimethyldibenzothiophene

Abstract

Two different kinds of γ-Al₂O₃ precursors: stick-like ammonium aluminum carbonate hydroxide and willow leaf-like boehmite could be selectively synthesized via a facile hydrothermal method by just adjusting reaction temperature. After heat treatment, γ-Al₂O₃ with two different morphologies (stick-like and willow leaf-like) were synthesized and used as supports for CoMo hydrodesulfurization catalysts. Fourier transform infrared spectroscopy of pyridine adsorption and NH₃-temperature-programmed desorption showed that stick-like γ-Al₂O₃ (ACH) and willow leaf-like γ-Al₂O₃ (AOH) exhibited a lower Lewis acidity than commercial γ-Al₂O₃. X-ray diffraction indicated that CoMo oxidic catalysts supported on ACH and AOH contained more β-CoMoO₄ phase. X-ray photoelectron spectroscopy and high resolution transmission electron microscopy revealed that after presulfurization, more CoMoS active sites and multilayered (Co)MoS₂ slabs formed on ACH and AOH supports, thereby creating catalysts with a higher hydrodesulfurization activity in the hydrodesulfurization of thiophene and 4,6-dimethyldibenzothiophene.