Synergistic interplay of dual active sites on spinel ZnAl2O4 for syngas conversion

The urgent need for efficiency improvement in the oxide-zeolite bifunctional syngas-to-hydrocarbon catalysis necessitates in-depth mechanistic insights into this reaction, especially for the initial syn- gas conversion over the oxide component, which remains poor. Herein, we comprehensively investigated syngas conversion over a representative ZnAl2O4 spinel oxide with state-of-the-art solid- state NMR technologies. Notably, specific surface dual active sites for syngas activation with-AlIV-OH center dot center dot center dot ZnIII- structure were unam- biguously identified. More importantly, the dynamic evolution of the reaction intermediates and active sites during the reaction pro- cess was elaborated at atomic level by a series of double resonance and multi-dimensional correlation NMR experiments. In combina- tion with in situ spectroscopic characterizations, we revealed the full cycle of the formate-methoxy-based pathway for the syngas- to-methanol conversion via synergistic interplay of the dual active sites. The in-depth atomic-level understanding of the catalytic mechanism will be beneficial to further rational design of high- performance catalysts for syngas conversion.