Insights into the Mechanism of High CO 2 Selectivity over Co 2 C-Based Fischer–Tropsch to Olefins

作者：Da Wang, Guangbo Liu, Chuanhui Zhang, Chao Feng, Jinhu Wu, Song Chen, Wenjie Xiang, Hao Huang, Zhihao Liu, Noritatsu Tsubaki · 发表于：ACS Catalysis · 年份：2025 · DOI：10.1021/acscatal.4c06992 · 被引用次数：10 · 研究领域：Catalysts for Methane Reforming、Catalysis and Oxidation Reactions、CO2 Reduction Techniques and Catalysts

The reasons for the too high CO 2 selectivity (near 50 C %) in Co 2 C-based Fischer–Tropsch to olefins (FTO) are not clear. Water–gas-shift (WGS) side reaction is thought to be responsible for this, but in-depth research is lacking. Here, we revealed the mechanism of the too high CO 2 selectivity in Co 2 C-based FTO. Kinetic studies showed that WGS reaction was more likely to occur than the hydrocarbon production reaction. In addition, a too severe WGS reaction would result in the formation of an H 2 -enriched and CO-deficient environment on the catalyst surface, which was not favorable for the generation of light olefins. Catalyst characterization results proved that the severe WGS reaction could also lead to the transformation of prismatic Co 2 C to spherical Co 2 C. Theoretical calculations demonstrated that prismatic Co 2 C (020) and Co 2 C (101) facets were dominant crystal facets for both FTO and WGS reactions. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy experiments found that the H 2 O produced in FTO completely participated in the WGS reaction. This clearly revealed why the CO 2 selectivity was close to 50 C % in FTO. Therefore, we believed that accelerating the desorption of H 2 O on the catalyst surface and preventing its readsorption are the key elements for inhibiting CO 2 formation in FTO.