Synthesis of a composite Fe–CaO-based sorbent/catalyst by mechanical mixing for CO2 capture and H2 production: An examination on CaO carbonation and tar reforming performance

Abstract

A composite CaO-based sorbent/catalyst (Fe/CaO-CA, CA stands for Ca12Al14O33) with good cyclic CO2 uptake characteristics, mechanical stability and tar reforming performance for the carbon-negative biomass calcium looping gasification (CLG) technology is prepared by mechanical mixing method. Different synthesis parameters regarding cyclic CO2 capture and Fe/CaO-CA's mechanical strength have been investigated. Different reaction conditions, such as low carbonation temperature, high calcination temperature, long cycles, and large particle size, were also investigated using a thermogravimetric analyzer. Results showed Fe/CaO-CA performed better in mechanical strength and carbonation when it was prepared by calcination at 750 °C for 4 h. In the carbonation temperature range from 650 °C to 850 °C, 750 °C was more favourable to promote CO2 capture during cyclic reactions. Fe/CaO-CA still exhibited promising CO2 uptake characteristics under severe calcination conditions, including high CO2 partial pressure, high temperature and long-term response up to 40 cycles. Additionally, the effect of Fe/CaO-CA on tar removal enhancement was also studied via the reforming of 1-methyl naphthalene (1-MN) by using a self-designed fixed-bed reactor. Fe/CaO-CA presented the maximum 1-MN conversion and the highest H2 yield (0.15 mol h−1 g−1) compared to the other three candidate samples (CaO, CaO-CA and Fe/CaO). Furthermore, Fe/CaO-CA showed the largest CO2 uptake capacity and the least amount of coke deposition during tar reforming.