Speaker
Description
The pressure to reduce greenhouse gas emissions is growing, which demands new and innovative technologies to produce mobile as well as stationary energy. The CO2 methanation offers a pathway to reduce greenhouse gas emissions by directly converting CO2 to CH4. This also plays a crucial role in "power-to-gas" (P2G) technologies by providing an approach to store excess renewable energy in the form of methane in an existing natural gas infrastructure without requiring any investment in additional storage infrastructure e.g., for H2, while the stored energy can be used when needed. However, methanation is a complex process due to its exothermic nature, interaction of the gas species with the catalyst, and possible catalyst degradation. Therefore, a deeper understanding is required for the methanation reaction, its different reaction pathways and side reactions. In this work, we aim to understand the direct production of synthetic natural gas from CO2 and H2 in a Sabatier process with the help of experiments over a Ni/Al2O3 catalyst. A detailed surface reaction mechanism is developed to extend the study numerically by validating the simulation results with the experimental data. A one-dimensional model, LOGEcat, based on a single-channel catalyst model, is used for kinetic modelling. Experiments as well as simulations have been performed at various conditions, such as temperature variation, N2 dilution to the inlet composition, and different H2/CO2 ratio. We have successfully captured the experimental trends using the kinetic model developed for the conditions considered for the analysis. The backward reactions become dominant at higher temperatures and the methanation is kinetically limited at low temperature. We note that the conversion of H2 and CO2 to CH4 reaches a maximum around 623 K and a higher H2/CO2 ratio also increases the conversion of CO2 to CH4 for ratios above H2/CO2= 4.
