Combined CO2 Capture & Methanation

Current multistage CCU technologies using renewable electricity to yield fuels suffer from low energy efficiency and require large capital expenditures. To increase the efficiency of the whole process and reduce its cost, a possible innovative solution is represented by the combined capture and hydrogenation of CO2. The idea is to trap CO2 from a CO2-containing stream (e.g. combustion flue gases) using a dual functioning material (DFM) composed of a highly dispersed supported adsorbent which provides at the same time the CO2 storage function and methanation active element to produce CH4 upon reaction with renewable H2 [1-2]. This process is operated cyclically by alternating phases where the DFM is exposed to the flue gas and CO2 is selectively adsorbed, and phases where H2 is fed and the stored CO2 is hydrogenated to methane [2]. Notably, by eliminating a thermal swing process, the conversion of CO2 to SNG using DFMs constrains the energy input to only renewable sources (in the form of H2), thus allowing the CO2 capture and utilization processes to approach carbon neutrality while integrating more renewable energy into the grid [2]. In a highly innovative scheme aimed at the process intensification, the DFM represents a CO2 carrier that is continuously circulated from a sorption reactor to a methanation reactor and vice versa [3]. Dual interconnected fluidized bed technology appears perfectly suited to perform the chemical looping CO2 Capture and Methanation process since it allows the recirculation of DFM particles between two reactors and ensures their efficient and independent temperature control. Therefore, we set out to experimentally investigate the key features capable to boost the overall performance of DFMs based on Ru and alkali metal (oxides) supported on high surface area aluminas with suitable mechanical and attrition resistance to be used in interconnected fluidized bed reactors. The general scope is to produce synthetic methane via an innovative, renewable energy driven, catalytic looping process, demonstrating effectiveness and reduction of greenhouse gas emissions while also addressing economic, regulatory, environmental and (critical) raw material constraints, as well as socio-economic impact related to the proposed technological pathway.