Enhancing bio-based chemical production and reducing pollutants emission through the synergistic effect of ZSM-5/CaO during hydrogen-deficient biomass pyrolysis

Abstract

The study proposed the use of ZSM-5/CaO as a catalyst to simultaneously improve the quality of pyrolytic products and reduce pollutants emission during the pyrolysis of hydrogen-deficient biomass, specifically cabbage waste (CW). Variables such as pyrolysis temperature and catalysts, including 5% ZSM-5, 5% CaO and 10% ZSM-5/CaO, significantly affected biomass conversion, yield, and products composition. Thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) analysis shows that the catalysts (5% ZSM-5, 5% CaO and 10% ZSM-5/CaO) reduced pollutants emission and increased value-added chemicals production by 24.96%, 28.5%, 17.39% and 75.04%, 71.5%, 82.1%, respectively compared to non-catalytic process as 34.18% and 65.82%. Moreover, these catalysts enhanced the relative yield of olefins, aromatics, and phenols to 23.5, 21.6, 27.6% for 5wt.%ZSM-5; 20.8, 18.7, 23.3% for 5wt.%CaO; 30.7, 38.6, 41.3% for 10wt.%ZSM-5/CaO, compared to the non-catalytic process' yield of 15.7, 10.7, 19.3%. Py/GC–MS analysis confirms that these catalysts also decreased PAH and oxygenates production to 13.5, 15.3% for 5wt.%ZSM-5; 11.8, 9.1% for 5wt.%CaO; 5.2, 4.7% for 10wt.%ZSM-5/CaO, in contrast to the non-catalytic process' 26.2, 28.7%. This confirms the synergistic effect of ZSM-5/CaO for upgrading bio-based chemicals and reducing pollutants emission.