Thermo-Chemical recycling of polypropylene via high-power microwave plasma gasification: Syngas and metal carbide production

• High-power 915 MHz microwave plasma utilized for Plastic thermo-chemical recycling via plasma gasification process. • Syngas and 99% pure solid carbon production from plasma gasification process. • Produced carbon microstructure characterization through STEM, TEM, EDS, BET, Raman spectroscopy, and laser diffraction. • Titanium carbide synthesis from produced solid carbon through short-term mechanical alloying. Difficult waste streams such as polypropylene (PP) are a nuisance vis-a-vis its disposal and treatment on account of its non-biodegradable nature, and they pose grave risks to humans and the environment. To prevent pollution, PP should be disposed of/ treated via sustainable and eco-friendly pathways such as thermochemical technologies. The current study investigates the viability of PP polymer granules gasification using an advanced high-power 100 kW microwave plasma system, integrated with a high-temperature reactor. The experiments were conducted with varying PP feed rates, ranging from 5 to 18 kg/h, and the output gas was analyzed under different conditions. Complete conversion of PP into syngas and carbon nanomaterials was achieved. The produced carbon nanomaterials were characterized using diverse techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray energy-dispersive (EDS), among others. More importantly, the synthesized nanomaterials were explored for applications in metal carbide synthesis through mechanical alloying. The results emphatically highlight the potential of microwave plasma technology for an efficient and eco-friendly valorization of polypropylene to produce usable energy in the form of syngas and value-added products such as nanomaterials and therefore, it is within the principles of circular economy.