Sorption-enhanced methane synthesis in fixed-bed reactors

Abstract

Production of synthetic methane as a substitute for natural gas has been widely discussed as a means of long-term energy storage with the potential of CO2 neutrality. While the maximum conversion of catalytic CO2 methanation is limited by the highly exothermic and pressure-dependent nature of the Sabatier reaction, high conversion at low pressure could be achieved at laboratory scale through sorption enhancement. The transient nature of this process requires new reactor designs and process engineering for large-scale reactors. We investigated pellet bed reactors from a process and reactor engineering perspective, particularly in the context of upscaling. Our results show that heat generation in the reactor remains a major challenge for process performance and product purity. The bed temperature is coupled with the water adsorption capacity of the catalyst, which in turn affects the reactor capacity. Consequently, this has an impact on the dynamics of the coupled adsorption and reaction front with implications for the design of larger reactors. The results provide a comprehensive understanding of the process and a guide for reactor engineering.