Tuning ethanol synthesis pathways from syngas: nanosheet-structured K-doped Co–MoS2 catalysts and the role of CVD sulfidation†

Abstract

This study investigates the effect of activation methods (H₂S sulfidation vs. chemical vapor deposition, CVD) on the catalytic performance of K-doped (Co)–MoS₂ nanosheets supported on activated carbon (AJ-3) prepared from different Co-precursors (cobalt acetate vs. cobalt nitrate) for selective and non-selective ethanol synthesis from syngas. Advanced characterization techniques, including nitrogen sorption, XRF, SEM, SEM-EDX, STEM-EDX, STEM-HAADF, TEM, HRTEM, and XPS, were utilized to analyze the structural, compositional, and morphological properties of the synthesized catalysts. Notably, the K–(Co)MoS₂/AJ-3 catalyst derived from cobalt nitrate via the CVD method exhibited exceptional ethanol selectivity, reaching 82%, significantly outperforming other alcohol products. In contrast, catalysts synthesized from cobalt acetate using the same CVD technique showed reduced activity for higher alcohol synthesis (HAS), favoring hydrocarbon formation and hydrogen spillover. Interestingly, the H₂S sulfidation method applied to inorganic precursors resulted in unexpected methanol selectivity. This work highlights the critical role of precursor type and preparation methodology in tailoring catalytic performance, providing a comprehensive understanding of how these factors influence product selectivity and efficiency.