Synergistic effect of CaO/HZSM-5 composite catalyst in regulating co-pyrolysis products of rice straw and PVC
Co-pyrolysis of biomass and waste plastics is one of the potential technologies to achieve the resourceful utilization of both,not only to prepare high value-added hydrocarbon-rich bio-oil,but also to achieve clean resourceful utilization of wastes and reduce environmental pollution.However,the products complexity limits its further application of co-pyrolysis technology.In this study,rice straw(RS),an agricultural waste,and polyvinyl chloride plastic(PVC)were used to investigate the individual and co-pyrolysis characteristics of them by thermogravimetric-mass spectrometry(TG-MS)and pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS),and the synergistic regulation law of the pyrolysis products by CaO and HZSM-5 composite catalyst.The results show that interactions exist between PVC and RS during the co-pyrolysis process,which promotes the production of aromatic compounds.The relative content of hydrocarbon compounds in tar is as high as 66.78%.The relative content of aromatics reaches 64.17%.Compared with RS pyrolysis,content of oxygenated compounds in the co-pyrolysis tar fraction decreases by 62.05%,which effectively improves oxidative stability of the tar.CaO/HZSM-5 composite catalyst shows better light aromatic selectivity compared with the individual one.The relative content of C4-C10 hydrocarbons in the pyrolysis tar increases by 2.81%and 5.06%,respectively.Under the synergistic effect of CaO/HZSM-5 composite catalyst,relative content of monocyclic aromatic hydrocarbons in the tar is 34.34%,which is larger than the theoretical calculated value of 33.03%.And relative content of PAHs is 28.21%,which is smaller than the theoretical value of 31.22%.In addition,the CaO/HZSM-5 composite catalyst promotes immobilisation of Cl in the form of chlorides such as CaCl2 in the char,which significantly reduces the gas-phase release of elemental Cl.
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维普
