Catalytic hydrolysis of methyl mercaptan and methyl thioether on hydroxyl-modified ZrO 2 : 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 (CH 3 SH), dimethyl sulfide (C 2 H 6 S) and H 2 O on the surface of hydroxyl-modified ZrO 2 were investigated using density functional theory (DFT) calculations. Additionally, a reaction mechanism was proposed for hydroxyl-modified ZrO 2 catalyzing the hydrolysis of CH 3 SH and C 2 H 6 S. The chemisorption of H 2 O molecules on the catalyst surface is attributed to H-O and H-Zr bonds. The chemisorption of CH 3 SH and C 2 H 6 S on the catalyst surface is attributed to Zr-S bonds. Competitive adsorption between the three gases exists only between CH 3 SH and C 2 H 6 S. It reveals the water-resistant properties of hydroxyl-modified ZrO 2 in desulfurization. The adsorption energies of the three gas molecules on the hydroxyl-modified ZrO 2 surface are in the order of CH 3 SH - (Zr) > C 2 H 6 S - (Zr) > H 2 O - (OH). The natural hydrolysis of CH 3 SH and C 2 H 6 S is a heat-absorbing process that cannot occur spontaneously. The rate-determining step for CH 3 SH catalytic hydrolysis is the formation of CH 3 O. The fracture of CH 3 SHO is the rate-determining step for C 2 H 6 S catalytic hydrolysis. The depletion of the surface hydroxyl groups can be replenished by the dissociation of H 2 O molecules. Hydroxyl-modified ZrO 2 facilitated the hydrolysis process of CH 3 SH to a greater extent than that of C 2 H 6 S. This study provides theoretical guidance for industrial applications and the design of hydroxyl-containing hydrolysis catalysts.