Hydrogenation of CO 2 into methanol at low-temperature on Cu-based catalysts is of great significance, but remains challenging to enhance activity. In this paper, we report an inverse catalyst constructed with nano-ZrZnO x supported on Cu particles with outstanding methanol synthesis performance at 220 ℃, two times higher than that of commercial Cu/ZnO/Al 2 O 3 catalysts under the same conditions. Detailed structure characterization and performance evaluation demonstrate that the ZrZnO x mixed oxide serves as the most active oxide-metal interface site for CO 2 hydrogenation. The ZrZnO x /Cu inverse catalyst increases the weak and medium CO 2 adsorption sites which are further demonstrated responsible to the methanol productivity. In situ DRIFTs studies reveal that the inverse interface accelerates the reduction of asymmetric formate intermediates and prevents the generation of CO. The combination of enhanced CO 2 activation capability and accelerated hydrogenation rate of intermediates over the ZrZnO x /Cu inverse catalyst probably contribute to the remarkable methanol synthesis performance from CO 2 .
Xiaohong Guo,Liqiang Deng,Xiaoyue Wang,Yongjie Zhao,Zhifan Cao,Pengwei Li,Congming Li
A pivotal aspect in advancing ZrZnO x catalysts for CO 2 hydrogenation lies in the modulation of Zr-O-Zn active sites, with ZnO facets emerging as potential modulators of site activity. Whereas the beneficial influence of non-polar ZnO facets on ZrZnO x catalysts has been scarcely documented. Our investigation reveals that ZrZnO x catalysts exposed non-polar ZnO facets (ZrZnO-n) exhibit superior methanol selectivity (74 %) compared to those with randomly exposed ZnO facets (ZrZnO-r, 35 %). Characterization results demonstrate that it is ascribed to the formation of highly active Zr-O-Zn (2−δ)+ sites on ZrZnO-n, which facilitate H 2 adsorption and dissociation. In situ spectroscopic studies and DFT calculations further substantiate this finding, demonstrating enhanced intermediates formation and more efficient hydrogenation processes. This research underscores the significance of ZnO facet engineering in the purposeful creation of efficient ZrZnO x catalysts for CO 2 hydrogenation.
Yangzhi Xu,Zhixue Hou,Shitao Peng,Shufang Zhao,Xiangxiang Chen,Chengwei Wang,Siyu Yao,Lili Lin
Cu-supported nano-sized oxides inverse catalysts hold promise for low-temperature methanol synthesis via CO 2 hydrogenation, but their performance is highly dependent on the synthesis process. For ZrZnO x /Cu inverse catalysts, this work demonstrates that methanol synthesis activity depends linearly on the oxygen vacancy (O v ) concentration within the ZrZnO x nanoparticles, but is independent with the Cu support. Through orthogonal experiments, it is found that the density of O v is highly sensitive to precipitants, and the space-time yield of methanol can exceed 900g CH3OH /kg cat /h as long as the ZrZnO x nano-oxides were precipitated by H 2 C 2 O 4 , which are 1.6 to 2.1 times greater than those of catalysts prepared using other precipitants. Comprehensive characterization reveals that H 2 C 2 O 4 promotes the formation of uniformly dispersed ZrZnO x nanoparticles with abundant oxygen vacancies (O v ). These findings demonstrate the critical role of O v -rich oxide nanoparticles in constructing high-performance inverse catalysts and offers valuable insights into the development of efficient and stable CO 2 -to-methanol systems.
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