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Title: Thermal Decomposition and Oxidative Decomposition Mechanism of HFC-134a by Experimental and DFT Method
题目：基于实验和DFT模拟的HFC-134a热解及氧化热解路径探究
Authors: XU Yunting, ZHANG Kai, DAI Xiaoye, SHI Lin
作者：许云婷，张凯，戴晓业，史琳
单位：清华大学热科学与动力工程教育部重点实验室，清华大学能源与动力工程系
Journal of Thermal Science, 2024, 33(5): 1990-2003.
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摘要
Abstract: In response to the Kigali Amendment to the Montreal Protocol and global low-carbon emission environmental requirements, the phase-out and decomposition of numerous HFC refrigerants have become urgent, necessitating efficient and mild decomposition methods. This study investigates the thermal decomposition and oxidative thermal decomposition pathways of the typical hydrofluorocarbon refrigerant HFC-134a, employing a combination of experimental and quantum chemical DFT simulation methods. Quantum chemical simulations reveal that the initial reaction bond cleavage serves as the rate-determining step during the thermal decomposition process, with the most easily detectable closed-shell products including CF2=CHF, HF, CH3F, CHF3, CH2F2, and CF4. Reactive oxygen species can significantly reduce the Gibbs free energy barrier for HFC-134a decomposition. To achieve efficient degradation of HFC-134a, appropriate catalysts should be developed and selected to increase the level of reactive oxygen species in the reaction system. Experimental studies further corroborate that HFC-134a may undergo degradation through distinct reaction pathways under varying temperature (240°C to 360°C) and pressure (0.1 MPa to 4.5 MPa) conditions, in agreement with simulation predictions.
摘要：鉴于《蒙特利尔议定书》基加利修正案和全球范围内的低碳减排环保要求，大量HFCs制冷剂亟待淘汰和降解，因此高效且温和的降解方法变得至关重要。本研究以典型的氢氟烃制冷剂HFC-134a为对象，采用实验与量子化学密度泛函理论（DFT）模拟相结合的方法，深入探讨了其热分解和氧化热解路径。量子化学模拟结果显示，在热分解过程中，起始反应化学键的断裂成为决速步骤，且最易生成的可检测到的闭壳层产物包括CF2=CHF、HF、CH3F、CHF3、CH2F2、CF4等。活性氧化物能显著降低HFC-134a分解的自由能垒。为实现HFC-134a的高效降解，应开发和选择适当的催化剂以提高反应体系中活性氧物质的水平。实验研究进一步证实，在不同温度（240℃至360℃）和压力（0.1 MPa至4.5 MPa）条件下，HFC-134a可能通过不同反应路径实现降解，这一结果与模拟预测保持一致。
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引用格式
XU Yunting, ZHANG Kai, DAI Xiaoye, SHI Lin, Thermal Decomposition and Oxidative Decomposition Mechanism of HFC-134a by Experimental and DFT Method, Journal of Thermal Science, 2024, 33(5): 1990-2003.
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