Study on the oxidative decomposition mechanism of R1234ye(E): A DFT study

Abstract

R1234ye(E) is an environmentally friendly working fluid that can be applied in refrigeration, heat pumps, and organic Rankine cycle systems, but it has issues with oxidative decomposition and flammability. Therefore, based on density functional theory, the oxidative decomposition mechanism of R1234ye(E) has been studied. The results indicate that the oxidative decomposition of R1234ye(E) is a typical chain reaction. The first stage is a chain-initiation reaction, where R1234ye(E) generates a large number of free radicals through initial self thermal decomposition reactions and collision reactions with oxygen. The most likely to occur is path 1–2, which is a homolytic reaction with an energy barrier of only 347.91 kJ/mol. The second stage is the chain-propagation reaction, including the reactions between R1234ye(E) and different free radical and subsequent reactions. The most likely to occur is path 5–1, which is a hydrogen abstraction reaction with an energy barrier of only 21.83 kJ/mol. The last stage is the chain-termination reaction, where the intermediates or products of the above reactions continue to react with the active free radicals until they are consumed. When all the reactants and free radicals are consumed and stable products are generated, the oxidative decomposition reaction ends. The research results provide a reference for the safe application of R1234ye(E) and other HFOs working fluids.