Reaction characteristics investigation of CeO2-enhanced CaSO4 oxygen carrier with lignite

The CeO2-enhanced CaSO4 as prepared was verified of enhanced reactivity and potential in situ desulfurizaiton, and thus applicable to use as oxygen carrier in coal chemical looping combustion for simultaneous carbon capture and gaseous sulfur removal. [Display omitted] Calcium sulfate (CaSO4) has been verified as a promising oxygen carrier (OC) in the chemical looping combustion (CLC) for its high oxygen capacity, abundant reserve and low cost, but its low reactivity and deleterious sulfur species emission from the side reactions of CaSO4 should be well considered for its wide application in CLC. In order to promote the reactivity of CaSO4 and increase its potential to inhibit the gaseous sulfur emission, a CeO2-enhanced CaSO4 OC mixed OC of core–shell structure was prepared using the combined template synthesis method. Reaction characteristics of the prepared CaSO4-CeO2 mixed OC with a typical lignite was first conducted and systematically investigated, and an improved reactivity of the prepared CaSO4-CeO2 mixed OC was demonstrated than its single component CaSO4 or CeO2 due to the fast transfer and exchange of oxygen from the CaSO4 substrate to coal via the doped CeO2. Furthermore, the solid products formed from the mixed CaSO4-CeO2 OC with the selected coal were collected and analyzed. Especially, evolution and redistribution of the sulfur species of different forms were focused. At the latter reaction stage of YN reaction with the CaSO4-CeO2 mixed OC, the SO2 emitted from the side reactions of CaSO4 was greatly diminished and the doped CeO2 was proven effective to directionally fix the SO2 released to turn into different solid sulfur compounds, which were determined as Ce2O2S, Ce2S3 and Ce2(SO4)3·5H2O and formed through the different pathways. In addition, good regeneration of the reduced CaSO4-CeO2 mixed OC could be reached in spite of the unavoidable interaction between the included minerals in coal and the reduced mixed OC. Overall, the combined template method-made CaSO4-CeO2 mixed OC reported herein was not only endowed with enhanced reactivity for coal conversion, but also owned the potential to directionally fix the gaseous sulfur emission, which is quite applicable as OC for simultaneous decarbonatization and desulfurization in the real CLC process.