Integrations of desulfurization, carbon capture, and methanation at an isothermal intermediate temperature

Abstract

Integrated CO2 capture and conversion (iCCC) technology has been recognized as the most efficient technology for Carbon Capture, Utilization, and Storage (CCUS). However, its industrialization is hindered by some unsolved engineering problems. Typically, sulfur impurities in most industrial flue gas will have significant poisoning effects on the process. Herein, we report integrations of SO2 removal, CO2 capture and conversion (iSCCC) at an isothermal intermediate temperature in a two-fixed-bed column system. By rationally developing the SO2 adsorbent pellets of ZnO-CaO, the CO2 adsorbent pellets of AMS-MgO, and the methanation catalyst pellets of Ni-La/Al2O3, each individual unit is optimized. Specifically, the in-situ dynamic structure evolution observed by the atmospheric aberration-corrected scanning transmission electron microscopy as well as the theoretical dynamics calculation provide an in-depth understanding of the CO2 adsorption and desorption performance changing with the temperature on the AMS-MgO pellets, which builds a bridge for a successful 99.3 % CO2 methanation efficiency. As a result, the matched iSCCC process demonstrates exceptional performance from simulated flue gas containing 1000 ppm SO2 and 20 vol% CO2, with full desulfurization and decarbonation and a CO2 conversion efficiency of 93.6 % after 20 cycles isothermally at 400 °C, superior to all the reported performance so far as we know, providing a promising route to practical large-scale iSCCC towards carbon neutrality.