Hasan Masitah, Asakoshi Toshiki, Muroyama Hiroki, Matsui Toshiaki, Eguchi Koichi
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
Phys Chem Chem Phys. 2021 Mar 11;23(9):5551-5558. doi: 10.1039/d0cp06257j.
Supported Ni catalysts are active in CO2 methanation. It is important to understand the reaction mechanism for the development of highly-active catalysts. In this study, we investigated the reaction pathways of CO2 methanation over Ni/Y2O3 and Ni/Al2O3 based on the adsorbates observed by diffuse reflectance infrared Fourier transform spectroscopy. For Ni/Al2O3, linear and bridged CO adsorbates were converted to nickel carbonyl hydride and/or formyl species, which would be further hydrogenated to methane. In contrast, the formation of formate adsorbates was specifically confirmed over Ni/Y2O3 under the CO2 methanation condition. The hydrogen molecule was activated by dissociatively-adsorbing on Ni particles. Then, the hydrogenation of formate adsorbates by the activated hydrogen species proceeded sequentially to form methane. The observed bridged CO species would not be a major intermediate for Ni/Y2O3.
负载型镍催化剂对二氧化碳甲烷化具有活性。了解反应机理对于开发高活性催化剂至关重要。在本研究中，我们基于漫反射红外傅里叶变换光谱观察到的吸附质，研究了二氧化碳在Ni/Y2O3和Ni/Al2O3上甲烷化的反应途径。对于Ni/Al2O3，线性和桥式CO吸附质转化为羰基氢化镍和/或甲酰基物种，这些物种会进一步氢化为甲烷。相比之下，在二氧化碳甲烷化条件下，在Ni/Y2O3上特别证实了甲酸盐吸附质的形成。氢分子通过在镍颗粒上解离吸附而被活化。然后，活化的氢物种对甲酸盐吸附质进行顺序氢化以形成甲烷。观察到的桥式CO物种对于Ni/Y2O3不是主要中间体。
