Microwave-assisted catalytic co-pyrolysis of waste rubber tyre and sugarcane bagasse for enhanced aromatic hydrocarbon production

Sugarcane bagasse (SCB) and waste rubber tyres (WRT) were simultaneously valorized into energy-rich liquids and functional carbon materials through microwave-assisted catalytic co-pyrolysis. The influence of feedstock blending ratios and alkali/oxide catalysts (KOH, NaOH, CaO) on product distribution and characteristics was systematically investigated. Co-pyrolysis exhibited strong synergistic effects compared with the individual pyrolysis of SCB and WRT, enabling improved energy efficiency and enhanced product selectivity. An optimum SCB: WRT ratio of 2.5:17.5 (g; g) with KOH increased the bio-oil yield from 26.19 to 37.72 wt% while promoting extensive deoxygenating and aromatic compound formation. NaOH mildly increased char production, whereas CaO shifted carbon conversion toward gaseous products, achieving a maximum gas yield of 53.54 wt%. Energy analysis revealed that co-pyrolysis substantially reduced specific microwave energy (391.5 kJ/g) demand relative to non-catalytic pyrolysis (810 kJ/g). FTIR, 13 C NMR, and GC-MS analyses demonstrated KOH superior catalytic role in producing hydrocarbon-rich oils, while XRD and BET confirmed that KOH-derived char possessed crystalline potassium phases and Mesoporous structures suitable for adsorption or catalytic reuse. Overall, microwave-assisted co-pyrolysis offers an efficient and circular pathway for upgrading SCB and WRT into high-value added fuels.