Catalytic hydrolysis of methyl mercaptan and methyl thioether on hydroxyl-modified ZrO: a density functional theory study.

The purification and removal of organic sulfur from natural gas is conducive to increasing the added value of natural gas and reducing environmental pollution. In this study, the adsorption properties of methyl mercaptan (CHSH), dimethyl sulfide (CHS) and HO on the surface of hydroxyl-modified ZrO were investigated using density functional theory (DFT) calculations. Additionally, a reaction mechanism was proposed for hydroxyl-modified ZrO catalyzing the hydrolysis of CHSH and CHS. The chemisorption of HO molecules on the catalyst surface is attributed to H-O and H-Zr bonds. The chemisorption of CHSH and CHS on the catalyst surface is attributed to Zr-S bonds. Competitive adsorption between the three gases exists only between CHSH and CHS. It reveals the water-resistant properties of hydroxyl-modified ZrO in desulfurization. The adsorption energies of the three gas molecules on the hydroxyl-modified ZrO surface are in the order of CHSH - (Zr) > CHS - (Zr) > HO - (OH). The natural hydrolysis of CHSH and CHS is a heat-absorbing process that cannot occur spontaneously. The rate-determining step for CHSH catalytic hydrolysis is the formation of CHO. The fracture of CHSHO is the rate-determining step for CHS catalytic hydrolysis. The depletion of the surface hydroxyl groups can be replenished by the dissociation of HO molecules. Hydroxyl-modified ZrO facilitated the hydrolysis process of CHSH to a greater extent than that of CHS. This study provides theoretical guidance for industrial applications and the design of hydroxyl-containing hydrolysis catalysts.