Microwave Pyrolysis of Automobile Shredder Residue Under the Action of ZSM-5 Molecular Sieve

Introduction: The recycling and utilization of scrapped vehicles has become an ex-tremely important issue all over the world. The purpose of this study is to investigate the effect of ZSM-5 molecular sieve on the microwave pyrolysis of automotive shredder residue. Methods: The elemental composition of Automotive Shredder Residue (ASR) was determined through industrial analysis and elemental analysis. Subsequently, thermal gravimetric experiments were conducted using ZSM-5 molecular sieves with different Si/Al ratios on ASR. The pyrolysis experiments were carried out using a constant-pressure microwave tube furnace at different tem-peratures and microwave powers, with ZSM-5 molecular sieves of different Si/Al ratios. The prod-ucts were analyzed by gas chromatography-mass spectrometry. Results: The results confirm that ZSM-5 molecular sieve with Si/Al = 15H could effectively reduce the initial activation energy of ASR pyrolysis to 93.278 kJ/mol. Comprehensive analysis determined the optimal experimental conditions to be: ZSM-5 molecular sieve with Si/Al = 15H, a pyrolysis temperature of 750°C, and a microwave power of 600W. The higher yields of both valuable gases and liquid products are achieved under optimal conditions. The combined yield of combustible gases (CH4 and H2) reached 48.66%. In the liquid fraction, aromatic substances constituted 94.44%, with aromatic hydrocarbons alone accounting for 92.59%. Discussion: The use of ZSM-5 molecular sieve significantly enhanced the pyrolysis efficiency of ASR by lowering the activation energy and promoting the formation of valuable products. The high selectivity toward aromatic hydrocarbons in the liquid fraction and the substantial yield of combus-tible gases suggest that microwave-assisted catalytic pyrolysis with ZSM-5 offers a promising route for converting ASR into high-value energy carriers. These findings highlight the potential of ZSM-5 as an effective catalyst for improving product quality and energy recovery from automotive shred-der residue. Conclusion: This research provides theoretical and experimental references for the catalytic micro-wave pyrolysis of ASR using ZSM-5 molecular sieves, demonstrating its feasibility and potential for efficient resource recovery from end-of-life vehicles.