Sensitivity study of integrated carbon capture and methanation process using dual function materials

Abstract

Integrated Carbon Capture and Methanation (ICCM) is a promising technology to produce Synthetic Natural Gas (SNG) via captured CO2 and renewable hydrogen. This work performed a sensitivity study on how operation pressure, the types of DFM and point source, and the catalytic metal loading in DFMs affect the performance of ICCM process. As Na-Ru/Al2O3 (Na-DFM), (Li-Na-K)NO3-MgO-Ni/CeO2-phy (Mg-DFM), and Ni5-CeLi (Li-DFM) were adopted as DFMs, the performances of ICCM process were investigated in the range of 0.1 Mpa-5.0 Mpa, showing elevated pressure is favorable to improving capture efficiency and the quality of SNG products, and reducing hydrogen consumption. Under the optimized operation conditions, Na-DFM based ICCM system shows the better overall performance than ICCM system using Mg-DFM or Li-DFM, which energy conversion efficiency, comprehensive energy consumption, and net CO2 emission are 82.74 %, –14.61 MJ/kg CO2, and –1.18 kg CO2/kg CO2, respectively. Circulation rate is the amount of DFMs necessary to be transferred between reactors to ensure the desired CO2 capture efficiency or SNG productivity; it heavily depends on the type of adsorbent component, capture/hydronation reactions, and the fraction of active adsorbent component in DFMs for CO2 transport. Na-DFM based ICCM systems using different point sources (Power Plant, Steel Plan, and Cement Plant) possess the approximate performances in terms of energy conversion efficiency, comprehensive energy consumption, net CO2 emission, and SNG composition; but when Steel Plan is the point source, Na-DFM based ICCM process features of low electricity and hydrogen consumptions. Cyclic redox reactions of catalytic metal and the cycled capture/hydrogenation proceed in parallel in ICCM process. The increased hydrogen consumption and strong exothermic effects arising from the redox reactions of catalytic metal leads to profound performance changes of ICCM system. Overall, the present work is providing comprehensive information and necessary data to guide the design and operation of an ICCM plant.