Ultrastable bifunctional multi-stage active metal catalysts for low concentration CO2 capture and in-situ conversion

Integrating CO2 capture and in-situ conversion is a promising means of processing low concentration CO2 in flue gas. The development of a low cost, highly stable catalyst to reduce the running cost is key to the development of this technology. The ultrastable bifunctional multi-stage active metal catalysts (Ca12Al14O33-y (Ca2Fe2O5)-CoxCaO) were synthesized by the solid phase synthesis method with low cost industrial powder raw materials. The catalyst was stabilized with calcium aluminate (Ca12Al14O33) and calcium ferrite (Ca2Fe2O5) as a substrate structural framework for CaO and enhanced the dispersion of CaO. It not only solved the problem of CaO deactivation due to sintering, pore collapse, and agglomeration in the continuous high-temperature reaction, but also showed excellent catalytic performance for reverse-water–gas-shift (RWGS) reaction. On the basis of calcium-looping and RWGS reaction, the high temperature CO2 capture and in-situ conversion process is realized in the same fixed-bed reactor for processing simulated flue gas with 16.7 vol% CO2. The results showed that at the optimum operating temperature of 610 °C, the catalyst still maintains a stable CO2 capture capacity, over 98% CO2 conversion rate and close to 100% CO selectivity after 100 cycles. The multi-stage active metal structure catalysts provided a unique construction idea for designing ultrastable catalysts for low concentration CO2 capture and in-situ conversion with great potential for industrial application.