Synthesis of biofuel via catalytic fast pyrolysis of wood-plastic composite over low-cost catalysts

Thermogravimetric (TG) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) analyses were performed to know the feasibility of low cost catalysts, γ-Al₂O₃, spent fluid catalytic cracking (FCC) catalyst, natural zeolite, to the pyrolysis of wood-plastic composite (WPC). Notably, the respective decomposition temperature of polyethylene and polypropylene in WPC was lowered with the use of low-cost catalysts during the catalytic fast pyrolysis (CFP). Furthermore, the lowest activation energy (Ea) of the CFP, obtained by the Ozawa method, was with the use of natural zeolite (127.5 kJ/mol), followed by the ones with the use of spent FCC catalyst (133.3 kJ/mol) and γ-Al₂O₃ (145.0 kJ/mol), respectively. In addition, the CFP over natural zeolite was less effective in terms of decreasing the production of low-quality hydrocarbons, paraffins and olefins having a wide carbon number distribution, and oxygenates compared to that over spent FCC catalyst and γ-Al₂O₃, respectively, due to the small pore size of natural zeolite. However, the largest amount of value-added aromatic hydrocarbons was produced in the CFP over natural zeolite among all the catalysts due to the high and strong acidity of natural zeolite.