Microwave-induced and catalytic pyrolysis of municipal domestic waste under multiple synergistic effects

Addressing the challenges of high tar content, which is difficult to degrade, and the susceptibility of catalysts to carbon deactivation in traditional pyrolysis processes, this paper proposes a novel research approach: integrating microwave induction with catalysis to facilitate the targeted degradation of liquid-phase tars that are typically hard to break down during the pyrolysis of municipal solid waste (MSW). Utilizing NiO/Al2O3 as the catalyst, the study investigates the pyrolysis behavior of municipal waste under microwave induction, examining changes in product distribution and composition. The results indicate that as the loading of NiO increases, the tar removal rate correspondingly rises, leading to a gradual increase in gas production. At a NiO content of 15%, the tar yield reached a minimum of 13%, while the gas production rate increased to 68%, resulting in a gas yield of 0.60 Nm3/kg and a carbon conversion rate of 72.9%. The effect of temperature on pyrolysis products was significant; as the temperature increased from 600 to 900 °C, the tar yield decreased from 32% to 17%, while the gas production rate rose from 38% to 63%. At 800 °C, increasing the catalyst dosage improved both tar degradation and gas production efficiency. However, when the catalyst dosage exceeded 25% of the mass of MSW, the catalytic efficiency stabilized. Compared to conventional pyrolysis, the introduction of microwave action significantly enhanced the pyrolysis behavior of MSW, further promoting tar cracking and consequently increasing gas yield.