Steering the reaction pathway of syngas-to-light olefins with coordination unsaturated sites of ZnGaOx spinel
Na Li, Yifeng Zhu, Feng Jiao, Xiulian Pan, Qike Jiang, Jun Cai, Yifan Li, Wei Tong, Changqi Xu, Shengcheng Qu, Bing Bai, Dengyun Miao, Zhi Liu, Xinhe Bao
Abstract
Abstract Significant progress has been demonstrated in the development of bifunctional oxide-zeolite catalyst concept to tackle the selectivity challenge in syngas chemistry. Despite general recognition on the importance of defect sites of metal oxides for CO/H 2 activation, the actual structure and catalytic roles are far from being well understood. We demonstrate here that syngas conversion can be steered along a highly active and selective pathway towards light olefins via ketene-acetate (acetyl) intermediates by the surface with coordination unsaturated metal species, oxygen vacancies and zinc vacancies over ZnGaO x spinel−SAPO-34 composites. It gives 75.6% light-olefins selectivity and 49.5% CO conversion. By contrast, spinel−SAPO-34 containing only a small amount of oxygen vacancies and zinc vacancies gives only 14.9% light olefins selectivity at 6.6% CO conversion under the same condition. These findings reveal the importance to tailor the structure of metal oxides with coordination unsaturated metal sites/oxygen vacancies in selectivity control within the oxide-zeolite framework for syngas conversion and being anticipated also for CO 2 hydrogenation.