A theoretical investigation on the hydrodesulphurisation mechanism of hydrogenated thiophene over Cu–Mo-modified FAU zeolite. Issue 6 (13th April 2022)

• Record Type: Journal Article
• Authors: Li, Suyang; Sun, Huai; Sun, Yingxin; Han, Sheng; Li, Qianggen
• Is Part Of: Molecular simulation. Volume 48:Issue 6(2022)
• Page Start: 495
• Page End: 516
• Publication Date: 2022-04-13
• Subjects: Hydrogenated thiophene -- hydrogenolysis desulphurisation -- ring-opening -- C–S bond cleavage -- hydrogen transfer; Molecular dynamics -- Computer simulation -- Periodicals; Statistical mechanics -- Computer simulation -- Periodicals; 539.6
• DOI: 10.1080/08927022.2022.2027407
• Languages: English
• ISSNs: 0892-7022

Abstract

ABSTRACT: We have theoretically investigated the hydrodesulphurisation (HDS) mechanism of hydrogenated thiophene over Cu–Mo-modified FAU zeolite using a two-layer ONIOM (our Own N-layered Integrated molecular Orbital and molecular Mechanics) study. The thiophene is hydrogenated to 2, 3-dihydrothiophene (2, 3-DHT), 2, 5-dihydrothiophene (2, 5-DHT) and tetrahydrothiophene (THT) due to moderate free energy barriers. Hydrogenolysis desulphurisation (HYD) and concerted direct desulphurisation (DDS) are discussed. Ring-opening, hydrogen transfer and C−S bond cleavage steps of thiophene derivatives are involved in the HYD process. The rate-determining steps are the hydrogen transfer step for 2, 5-DHT and C−S bond cracking step for 2, 3-DHT and THT. The concerted DDS pathway is probably more favourable than the HYD pathway in the desulphurisation of 2, 5-DHT. The difference charge density (DCD) analysis reveals that for the ring-opening process, the electrons are migrated from the organic chain to the Cu–Mo catalytic centre. The reduced density gradient (RDG) plots indicate that both steric hindrance and a weak van der Waals (VDW) interaction exist between organic fragment and catalytic centre for all transition states (TSs). The localised orbital locator (LOL) maps suggest that there are strong covalent interactions and weak VDW interactions between the atoms in the forming chemical bonds.