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

Abstract

K-(Me)MoS 2 catalysts (Me = Co, Fe, Ni) supported on activated carbon were synthesized via the incipient wetness impregnation method. The catalysts were characterized using low-temperature N 2 -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 MoS 2 /AG-3 and (Me)MoS 2 /AG-3 catalysts. Conversion decreased as follows: FeMoS 2 > MoS 2 ≥ NiMoS 2 > CoMoS 2 > K-CoMoS 2 > K-NiMoS 2 > K-MoS 2 > KFeMoS 2 . K-addition into (Me)MoS 2 /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 MoS 2 /AG-3 and CoMoS 2 / AG-3 catalysts.