Enhanced production of C2–C4 alkanes from syngas via a metal sulfide–support interaction over Ni–MoS2/Ce1−xLaxO2−δ

Abstract

Direct conversion of syngas for selective production of light alkanes (C₂–C₄), driven by the demand for renewable petrochemicals and fuels, is promising but challenging due to the low selectivity. This study reports the interaction among the metal (Ni–Mo) sulfides and support (Ce_1−xLa_xO_2−δ) that serves to appreciably enhance the target alkane selectivity without a severe loss of catalytic activity or stability. Characterization measurements (e.g., XPS, TEM-EDX, TPR, TPR-S, TPS, CO-TPD, Raman and in situ DRIFT of CO adsorption) demonstrate that the interaction between Ni and MoS₂ generated the active NiMoS phase, which facilitated the C–C chain growth, achieving up to 75.9% selectivity of C₂–C₄ alkanes at a CO conversion of 25.1%. Monolayer dispersed sulfide species (NiMo^VO_xS_y-II) in strong interaction with the support, generated via low-temperature sulfidation, was favorable for the CO adsorption and delivered higher conversion rates relative to that of the conditional multi-stacked metal sulfides. This work establishes tuning the interaction between the metal sulfides and support as an alternative means to selectively produce C₂–C₄ alkanes in direct syngas conversion.