Barium aluminate improved iron ore for the chemical looping combustion of syngas

Abstract

Chemical looping combustion (CLC), as an advanced combustion technology, has attracted much attention because of its applicability to a variety of fuels and its ability to achieve inherent carbon capture. However, CLC of municipal solid waste (MSW) has been seldom reported. In this study, we investigated the CLC of simulated MSW-derived syngas using iron ore (IO)-based oxygen carriers (OCs). To enhance the redox activity of the IO, barium aluminate (BaAl2O4) was used for the first time as a promoter of the OC. It was found that the surface decoration with BaAl2O4 significantly improved the redox performance of IO over the temperature range of 700–900 °C. Almost 100% syngas combustion over 30 redox cycles was achieved by IO modified with 10% of BaAl2O4 (IO-10BA) at a space velocity of 31700 h−1, whereas only ~70% combustion efficiency was achieved by pristine IO. Additionally, BaAl2O4 doping improved the oxygen transport capacity of the IO by 36.2%. Based on complementary characterization analyses, we found that more oxygen vacancies were formed in the modified OC due to the oxygen non-stoichiometry nature of the BaAl2O4 and its interaction with the iron oxide species. This interaction facilitated the rapid migration of the lattice oxygen in the bulk phase, thereby enhancing the reactivity and increasing the oxygen transport capacity of the OCs. The addition of BaAl2O4 also induced a change to the solid morphology, making the OC become more porous over redox cycles, a phenomenon that was partly responsible for the high combustion performance of the IO-10BA.