Optimization of DFMs (dual function materials) for combined CO2 capture and methanation

Acting against climate change is one of the greatest challenges facing today’s society. Greenhouse gas emissions are the main cause, leading to the emergence of a variety of solutions to mitigate them. Among these solutions, Dual Function Materials (DFMs) can both capture CO2 and convert it into methane via its reaction with hydrogen. Allowing to produce a fuel that is both safer than hydrogen and carbon-neutral. The properties of DFMs emerge from the simultaneous presence of basic and catalytic sites on the material. The proximity of these sites enhances reaction performance. Various compositions have been studied in the literature. In this work the DFM studied is 6%Na2O-5%Ru/γ-Al2O3, synthesized via two successive wet impregnations. This work focuses on the optimization of the DFM via two axes, the synthesis process and the composition. First, different calcination temperatures were tested for ruthenium impregnation. The objective was to understand the impact of calcination temperature on dispersion and Ru particle size and its impact on catalytic performance of the resulting DFM. Then the effect of ruthenium loading was tested. To characterize the samples, N2 physisorption, XRD, CO2 TPD and in situ DRIFTS measurements were carried out. For each sample, a catalytic testing was carried out to test their performance in converting CO2 to methane using a MS setup. Our results show that higher calcination temperature favors bigger particle size but catalytic testing shows that calcination temperature and particle size only has a marginal impact on catalytic performances. Concerning Ru loading, better performances are observed for higher Ru loadings.