Selective Preparation of Aromatic Hydrocarbons by Catalytic Pyrolysis of Pine Wood with Fly Ash-Based HZSM-5
Fly ash was utilized as a raw material to prepare fly ash-based HZSM-5(FA-HZSM-5)catalysts by acid washing and alkali fusion pretreatment coupled with hydrothermal method.The catalysts were then applied to the catalytic pyrolysis of pine wood for the production of aromatics.The effects of pretreatment parameters such as hydrochloric acid concentrations and alkali/ash ratios on the physicochemical properties of FA-HZSM-5 were systematically investigated.Furthermore,the regulatory mechanisms of catalyst preparation conditions and pyrolysis process parameters on the selective preparation of aromatics were revealed.The results show that FA-HZSM-5 possessed a larger pore structure and mild acid strength than commercial HZSM-5.These characteristics were conducive to generating monocyclic aromatic hydrocarbons(MAHs)while significantly reducing the yields of polycyclic aromatic hydrocarbons(PAHs).When the hydrochloric acid concentration was 10％,the alkali/ash ratio was 1.5,the pyrolysis temperature was 650 ℃,and the catalyst/pine ratio was 20,the maximum aromatics yield reached 10.82％.Among these,the MAHs yield was 7.65％,and the PAHs yield was 3.17％,reduced by 26.11％compared to the yield from catalytic pyrolysis using commercial HZSM-5.
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