(212b) Chemical Looping Gasification with Red Mud As the Oxygen Carrier and Catalyst for Hydrogen-Rich Syngas Production

Chemical looping gasification (CLG) is an innovative, air-blown technology used to produce H₂-rich syngas, with a relatively high ratio of H₂:CO, where air does not directly contact fuel. A CLG system consists of two separate reactors: an air reactor (AR) and a fuel reactor (FR). The oxygen and heat required for fuel gasification is transported from the AR to the FR via a solid oxygen carrier (usually a transition metal oxide), reducing the energy demand required for oxygen separation. Meanwhile, the depleted oxygen carrier (OC) can catalyze in-situ water gas shift reaction, producing H₂-rich syngas ready for Fisher-Tropsch synthesis and eliminating the costly external water-gas shift reactor. The dual-function of OC makes it a key point for process intensification in this technology. Red mud, byproduct from alumina industry, has been proposed as a cost-effective OC material for the chemical looping process by UKy-CAER. This work further investigated the performance of red mud as an oxygen carrier and catalyst for the CLG process in a fluidized bed reactor. It was verified that the gasification rate of coal char was enhanced approximately by 1.5-3 times in the bed of red mud particles. Deactivation and agglomeration was not observed during 20 continuous cycles. The effect of OC:fuel mass ratios on the produced syngas composition was studied as well. As the ratio of OC:fuel decreased, syngas fraction increased due to the oxygen-lean condition. H₂:CO ratios in the range of 2.1-4.5 were obtained in the bed of reduced red mud, demonstrating the catalytic function of red mud in the water gas shift reaction.