An in situ FTIR-DRIFTS study on CDRM over Co–Ce/ZrO2: Active surfaces and mechanistic features

Abstract

CDRM (Carbon Dioxide Reforming of Methane) is an effective route to utilize the most abundant greenhouse gases, CH4 and CO2, to produce synthesis gas. This study aims to define the CDRM features, including both surface characteristics and mechanistic properties, of Co–Ce/ZrO2 catalysts via FTIR-DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy). In this manner, CO adsorption, CDRM reaction and cyclic experiments are applied to Co–Ce/ZrO2 system under different operating conditions. Accordingly, it is verified that Co sites are responsible for CH4 activation. Ceria has a strong interaction with oxygen related groups, due to its enhanced oxygen transfer ability. Co/Ce ratio dominantly affects surface properties of the catalysts and causes variations on type and amount of surface intermediates during the reaction. CO2 activation occurs at ZrO2 sites, especially at their oxygen vacancies. The CH4/CO2 feed ratio is crucial in maintaining C–O balance in the reaction medium. Finally, a possible reaction route, valid for all tested catalysts, is discussed.