Mechanism of synergistic effects and kinetics analysis in catalytic co-pyrolysis of water hyacinth and HDPE

Abstract

Co-pyrolysis of water hyacinth (Eichhornia crassipes) and HDPE is a commercially effective method to mitigate the pressure of environmental pollution and the problem of invasive alien species. In this paper, the thermal behavior and kinetic evaluation of the two raw materials with or without catalysts have been investigated. The mechanism of catalytic pyrolysis was also investigated by analyzing the free radicals generated during catalytic pyrolysis. The results showed that the heating rates had a negligible effect on the pyrolysis process. The addition of HDPE could reduce the formation of char and be conducive to the complete reaction with the higher value of the comprehensive pyrolysis index (CPI). The sample containing 75% water hyacinth exhibited the strongest synergistic effect in co-pyrolysis, with the lowest value of the difference between experimental and theoretical weight loss (ΔW) and activation energy among the co-pyrolysis samples. However, the sample with 25% water hyacinth showed an inhibiting effect due to the positive value of ΔW in the main decomposition temperature. Whereas the sample containing HZSM-5 had the lowest ΔW and activation energy compared to the blends without catalysts indicating that the presence of HZSM-5 was conducive to the synergistic effect in co-pyrolysis. The promotion was then demonstrated to be due to the abundance of free radicals generated in the catalytic process. This paper aims to provide some suggestions on the solution for the alleviation of environmental and energy crisis.