Atomic perspective elucidates mixed alcohol synthesis from syngas on bilayered (K)/MoS₂ catalysts

Syngas serves as a crucial link between non-petroleum-based carbon resources and commodity chemicals. Among various conversion routes, the catalytic transformation of syngas into ethanol and other mixed alcohols represents a highly attractive option. K-modified MoS₂ systems exhibit notable activity and selectivity in low-carbon alcohol synthesis. To elucidate the correlation between product selectivity and catalyst structure, and to design efficient catalysts for the synthesis of specific single products, density functional theory (DFT) was employed to explore the transition states of elementary steps involved in syngas conversion to mixed alcohols on bilayer (K)/MoS₂ catalysts. The results indicate that CO hydrogenation on the S-edge sites of the MoS₂(100) facet mainly yields C₁ species, whereas ethanol is primarily produced at the Mo-edge sites. Moreover, K doping enhances CO activation and C-C coupling at the Mo-edge. The most favorable pathway for ethanol synthesis at the Mo-edge is identified as CO → HCO → CHOH → CH → CHCO → CH₂CO → CH₃CO → CH₃CHO → CH₃CH₂O → CH₃CH₂OH, with the key step being the hydrogenation of CH₃CO to CH₃CHO, which requires an energy barrier of 0.73 eV. This work offers comprehensive and valuable guidance for the subsequent modification and design of C-C coupling catalysts.