Municipal Solid Waste SMO-Assisted Gasification for High-Quality Syngas Production Using a Thermal Analysis Tool

Municipal solid waste (MSW) management faces increasing pressure due to rapid urbanization and the need for low-emission energy systems. This study investigates the thermogravimetric gasification behavior of Chinese MSW under CO2, mixed air-CO2, and SrMnO3 (SMO) oxygen-carrier atmospheres to identify pathways for producing clean and higher-quality syngas. Using TGA-QMS, the gasification stages were monitored qualitatively and quantitatively over the temperature range of 750–1000 °C, while complementary FTIR, XRD, SEM-EDS, and ICP-OES analyses were employed to characterize the fresh waste and ash samples. Results show that CO2 gasification is strongly dependent on temperature and concentration, producing CO via Boudouard reaction, resulting in a gas composition of 73% CO and 27% CO2. An air-CO2 mixture as a gasification agent shifted conversion toward combustion, producing high CO during oxidation but suppressing gasification, yielding syngas dominated by 90% CO and 10% CO2. Introducing SMO significantly altered the reaction pathway via lattice-oxygen transfer: 7–56.75 mg SMO produced up to 97% CO and 3% CO2, without external oxidants, demonstrating superior per-unit oxidizing capacity compared to CO2. A mild synergistic effect was observed in the mixed CO2-SMO investigation, where CO formation exceeded that obtained with CO2 alone but remained lower than that in SMO-only gasification. In general, SMO-enabled oxygen donation provides a promising low-dilution, high-selectivity route for MSW gasification within thermogravimetric regimes.