A Study of the Effects of K‑Modification and (Co, Ni, Fe)-Promotion on a Supported MoS2‑Based Catalyst for Ethanol Conversion

• Published in: Journal of physical chemistry. C 2024-07, Vol.128 (28), p.11507-11521
• Main Authors: Dipheko, Tshepo D., Osman, Mohamed E., Permyakov, Evgeny A., Maximov, Vladimir V., Ponkratova, Yuliia Y., Dorokhov, Victor S., Cherednichenko, Alexander G., Kogan, Victor M.
• Format: Article
• Language: English
• Subjects: C: Energy Conversion and Storage
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.4c01872

K-(Me)­MoS2 catalysts (Me = Co, Fe, Ni) supported on activated carbon were synthesized via the incipient wetness impregnation method. The catalysts were characterized using low-temperature N2-adsorption, SEM-EDX, XRD, and TEM. The catalysts were evaluated in an ethanol conversion reaction using a fixed-bed reactor to investigate the influence of catalytic active phase composition on the yields of various products. It had been found that K and Co­(Ni, Fe) incorporation contributed to the significant changes in catalytic behavior of sulfide catalysts. The addition of K resulted in partial poisoning of the active sites, resulting in a decrease in catalytic activity when compared to the reference MoS2/AG-3 and (Me)­MoS2/AG-3 catalysts. Conversion decreased as follows: FeMoS2 > MoS2 ≥ NiMoS2 > CoMoS2 > K-CoMoS2 > K-NiMoS2 > K-MoS2 > KFeMoS2. K-addition into (Me)­MoS2/AG-3 increased the yield of alcohol at the expense of acetate and hydrocarbons. It reduced the probability of C–O bond breaking in the adsorbed intermediate and altered selectivity away from alkyl fragment toward alkoxide fragment formation. This allowed us to suppose that K somewhat promotes sites responsible for higher alcohol synthesis. Catalysts free of K were shown to be more advantageous for the synthesis of ethyl acetate, resulting in high yields, particularly with the use of MoS2/AG-3 and CoMoS2/AG-3 catalysts.