Theoretical Study on Catalytic Pyrolysis of Benzoic Acid as a Coal-Based Model Compound

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• 作者：Ming-Fei Wang ; Zhi-Jun Zuo ; Rui-Peng Ren ; Zhi-Hua Gao ; Wei Huang
• 刊名：Energy & Fuels
• 出版年：2016
• 出版时间：April 21, 2016
• 年：2016
• 卷：30
• 期：4
• 页码：2833-2840
• 全文大小：618K
• 年卷期：0
• ISSN：1520-5029

文摘

Benzoic acid (C₆H₅COOH) is selected as a coal-based model compound, and its catalytic pyrolysis mechanisms on ZnO, γ-Al₂O₃, CaO, and MgO catalysts are studied using density functional theory (DFT) compared to the non-catalytic pyrolysis mechanism. DFT calculation shows that the pyrolysis process of C₆H₅COOH in the gas phase occurs via the direct decarboxylation pathway (C₆H₅COOH → C₆H₆ + CO₂) or the stepwise decarboxylation pathway (C₆H₅COOH → C₆H₆COO → C₆H₆ + CO₂). For C₆H₅COOH catalytic pyrolysis on the ZnO (101̅0) surface, the preferred reaction pathway is C₆H₅COOH → C₆H₅COO + H → C₆H₆ + CO₂, whereas the preferred reaction pathway on γ-Al₂O₃ (110), CaO (100), and MgO (100) surfaces is C₆H₅COOH → C₆H₅COO + H → C₆H₅ + CO₂ + H → C₆H₆ + CO₂, indicating that the presence of catalysts changed the pyrolysis mechanism of C₆H₅COOH. In addition, dissociative adsorption of C₆H₅COOH is observed on these surfaces. It is found that ZnO (101̅0), MgO (100), and CaO (100) are beneficial to C₆H₅COOH decomposition, but γ-Al₂O₃ (110) is disadvantageous to the C₆H₅COOH decomposition. At the same reaction temperature, the rate constants show the order: k(ZnO) > k(MgO) > k(CaO) > k(no catalyst) > k(γ-Al₂O₃).