Fast Catalytic Co-pyrolysis Characteristics and Kinetics of Chlorella Vulgaris and Municipal Solid Waste over Hierarchical ZSM-5 Zeolite

Abstract

In this work, catalytic co-pyrolysis characteristics and kinetics of chlorella vulgaris (CV), municipal solid waste (MSW), and their blends over hierarchical ZSM-5 zeolite were studied by thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Moreover, three zeolite additives, namely, ZSM-5, Al-MCM-41, and Al-SBA-15, were selected to compare their effects on catalytic co-pyrolysis and coking characteristics with hierarchical ZSM-5 zeolite. Results showed that co-pyrolysis of CV and MSW demonstrated significant synergistic effects at 260–330 °C, especially at the ratio of 5:5. Two model-free methods, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS), were used to calculate the kinetic parameters. Product distribution results demonstrated that co-pyrolysis could improve pyrolysis products by increasing monocyclic aromatic hydrocarbons and aliphatic hydrocarbons as well as reducing polycyclic aromatic hydrocarbons and nitrogen compounds. Compared with other three kinds of zeolite additives, hierarchical ZSM-5 with both micropores and mesopores achieved superior monocyclic aromatic hydrocarbon selectivity (34.14%) and inferior acid selectivity (9.54%) for co-pyrolysis, thereby satisfying the preferred criteria. In addition, the difference from the thermogravimetric curve between after pyrolysis and fresh zeolites indicated that hierarchical ZSM-5 also had the best coking resistance. In brief, co-pyrolysis of chlorella vulgaris and municipal solid waste with hierarchical ZSM-5 was definitely a feasible way for high-quality bio-oil generation.