Pyrolysis kinetics, thermodynamics of PTA sludge and product characterization of cyclic in-situ catalytic pyrolysis by using recycled char as a catalyst. (15th July 2022)

• Record Type: Journal Article
• Authors: Xing, Xinxin; Zhao, Hongyu; Zhou, Lili; Wang, Yangang; Chen, Haijun; Gao, Ying; Wang, Yinfeng; Zhu, Yuezhao
• Is Part Of: Energy. Volume 251(2022)
• Publication Date: 2022-07-15
• Subjects: In-situ catalytic pyrolysis -- Kinetics -- Carbon conversion -- Pyrolysis char -- PTA sludge; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2022.123821
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: Pyrolysis is an effective way for the sludge harmless, reduction treatment and resource utilization. In this study, the pyrolysis kinetics and thermodynamics of PTA sludge was evaluated. Afterword, a cyclic in-situ catalytic pyrolysis of PTA sludge by using recycled char as a catalyst was conducted. The product characterization, e.g. pyrolysis syngas as well as the catalytic effect of pyrolysis char, were analyzed. The results demonstrated that the Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW), and Starink model-free methods have good agreement on kinetic parameters, the average activation energy was calculated at 295.18, 286.62, and 290.55 kJ/mol, respectively. Meanwhile, thermodynamic parameters, e.g. the variations in enthalpy (Δ H ), entropy (Δ S ), and Gibbs free energy (Δ G ), were evaluated based on the deduced kinetic results, whereby the suitable pyrolysis temperature was determined at 973 K. The results of cyclic in-situ catalytic pyrolysis showed that the pyrolysis char could promote tar cracking, which greatly increased the yield of pyrolysis syngas. After five rounds of in-situ catalytic pyrolysis, the yield of pyrolysis syngas increased from 0.089 L/g to 0.176 L/g and the carbon conversion increased from 24.8% to 36.5%, respectively. Highlights: A cyclic in-situ catalytic pyrolysis with recycled char as a catalyst was proposed. The pyrolysis kinetics and thermodynamics of PTA sludge were evaluated. The carbon conversion was increased to 36.5% by five rounds of in-situ pyrolysis. The char has effects on improving the yield of syngas by promoting cracking of tar.