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

Abstract

•Specific surface dual active sites on ZnAl2O4 for syngas conversion are identified •Dynamic interaction between the active sites and intermediates is elaborated •Synergistic interplay of heteroatoms for syngas conversion is revealed 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 syngas 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···ZnIII– structure were unambiguously identified. More importantly, the dynamic evolution of the reaction intermediates and active sites during the reaction process was elaborated at atomic level by a series of double resonance and multi-dimensional correlation NMR experiments. In combination 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. 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 syngas 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···ZnIII– structure were unambiguously identified. More importantly, the dynamic evolution of the reaction intermediates and active sites during the reaction process was elaborated at atomic level by a series of double resonance and multi-dimensional correlation NMR experiments. In combination 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.