| 摘要: |
| 我国面临巨大HFCs制冷剂销毁压力，亟需研究高效且温和的HFCs制冷剂降解方法。本文结合实验与量子化学计算，以典型HFCs制冷剂HFC-134a为研究对象，以降解率为主要衡量标准，研究制冷剂降解的高效途径。从量子化学的角度，研究了HFC-134a自热分解与氧化热解条件下的反应路径，在两条路径下，均易产生CHF=CF2与HF等可检测到的稳定产物。自热分解过程中，第一步化学键的断裂是决速步骤。氧化热解路径相较自热分解路径，反应能垒低，有利于反应快速发生。从实验的角度，发现在240~360 ℃温度范围内，随着温度的提高，HFC-134a的降解率由11%提高至66%，通过反应动力学常数拟合计算，得到HFC-134a的指前因子为7471.04 s-1，表观反应活化能为54.16 kJ/mol，与模拟计算所得化学反应能垒相吻合。 |
| 关键词: 反应能垒 表观反应活化能 氧化热解 密度泛函方法 HFC-134a |
| DOI： |
| Received:August 10, 2022Revised:August 30, 2022 |
| 基金项目:国家自然科学基金（52176011），清华大学-山西清洁能源研究院创新种子基金项目 资助。 |
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| Mechanism and Experimental Studies of HFC-134a Oxidative Decomposition Mechanism |
|
Xu Yunting, Zhang Kai, Dai Xiaoye, Shi Lin
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| (Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of energy and power engineering, Tsinghua University) |
| Abstract: |
| There is significant emphasis on the destruction of HFC refrigerants in China, culminating in an urgent need to explore efficient and mild HFC refrigerant degradation methods. In this study, a typical HFC refrigerant, HFC-134a, was chosen as the object of combined experimental studies and quantum chemical calculations, and the degradation rate was considered the main criterion for exploring the high-level pathway of refrigerant degradation. In terms of quantum chemistry, the reaction paths of HFC-134a under pyrolysis and oxidative decomposition conditions were explored. Under both paths, detectable stable products such as CHF=CF2 and HF were easily produced. During pyrolysis, the first step in the chemical bond cleavage is the rate-determining step. Compared to the pyrolysis path, the oxidative decomposition path has a lower reaction energy barrier, which is conducive to the rapid occurrence of the reaction. Experimental results showed that the degradation rate of HFC-134a increased from 11% to 66% with the increase in temperature in the range of 240–360 ℃. By fitting the kinetic constant of the reaction, the pre-exponential factor (A) of HFC-134a was determined as 7471.04 s-1, and the activation energy (Ea) was 54.16 kJ/mol, which were consistent with the simulated chemical reaction energy barrier. |
| Key words: chemical reaction energy barrier activation energy(s) oxidative decomposition density functional theory (DFT) HFC-134a |
