Comparative study of hydrogenolysis of a C-X bond in three homologous heterocyclic compounds of chemical formula C5H10X with X = S, O and NH

Abstract

A theoretical study of hydrogenolysis of a C-X bond of 2-methyltetrahydrothiophene (2-MTHT), 2methyltetrahydrofuran (2-MTHF) and 2-methylpyrrolidine (2-MP) molecules, over molybdenum disulfide (MoS2) and tungsten disulfide (WS2) has been performed by MP2 calculations in the Lanl2DZ basis set. Both catalysts were modeled by catalytic sites with three anionic vacancies MoS3H3 + and WS3H3 + respectively. The temperature and pressure conditions respected in the study are respectively 573 K and 70 atm. The obtained results shown that, the Hydrogenolysis of a C-X bond of methyled carbon of 2-MTHT and 2-MTHF molecules led to the formation of 1pentanethiol and 1-pentanol adsorbed over the each catalyst. On the other hand, in the case of the 2-MP molecule, the catalytic site was implicated in the reaction with formation of hydrogen sulfide (H2S). The Hydrogenolysis activation energies of various transformations were variable from MoS2 to WS2 catalysts except for 2-MTHT. In presence of a same kind of catalyst, the activation energies of Hydrogenolysis of the C-X bond (methyled carbon atom) of 2-MTHF and 2MTHT increase in the order X = O, S.