A Thermodynamic Analysis And Computational Simulation Study On The Preparation Mechanism Of High Purity Anhydrous InCl₃

High purity anhydrous InCl₃ is now widely used as a precursor in new functional materials such as solar cells,ITO films,and catalysis.In the production of high-purity anhydrous InCl₃,the products caused by the current preparation process contain organic impurities,low quality,incomplete dehydration,long preparation period,complicated processes,etc.The high-purity anhydrous InCl₃ produced in China has high production cost,low economic value,and can not be used for large-scale production in factories,which seriously affects the further development of the InCl₃ preparation industry.In order to study the preparation of high purity anhydrous InCl₃ by metal indium direct chlorination method,the reaction mechanism and internal microscopic process of preparing high purity anhydrous InCl₃ were studied by metallurgical physics and molecular simulation.It can provide theoretical basis for actual production through theoretical calculation.Based on the thermodynamic equilibrium calculation,the Gibbs free energy function and the equilibrium partial pressure were used to analyze the direction and limit of the reaction in the system,and the main products obtained by the reaction at different temperatures were determined.The molecular dynamics simulation calculation is used to investigate the bonding mode and motion state of the internal indium atoms and chlorine atoms in the InCl₃ reaction,thus revealing the microscopic state of the reaction.The thermodynamic calculation and molecular simulation results show that the main product of indium and chlorine reaction at the temperature below the limit temperature is InCl₃ which is decomposed by In₂Cl₆.When the temperature exceeds the limit temperature,the main product InCl₃ can be directly obtained,but the thermodynamically calculated limit temperature is 665℃,and the limit temperature calculated by molecular simulation is 650℃,and there is a deviation of 15℃ between them.In view of the above deviations,this paper designs special reaction equipment and process flow experiments to verify based on the calculation simulation.The results show that the experimental and simulation results are in good agreement,and the molecular simulation perfectly presents the microscopic mechanism of macroscopic phenomena in the experiment.From a microscopic point of view,at less than 650℃,the intermediate produced by the reaction is pre-formed into In₂Cl₆ and then decomposed into InCl₃,so the corresponding InCl₃ yield must have a certain loss;after 650℃,the resulting intermediate will be directly conversion to InCl₃,so the corresponding InCl₃ yield must be improved,but continue to increase the temperature will not continue to increase the reaction rate.The experimental results and thermodynamic theory calculate the temperature difference of 15℃.The error is mainly because the thermodynamic analysis carried out in this paper is based on the standard molar Gibbs free energy,which is related to the actual calculation of the required Gibbs free energy.There are certain differences and the 15℃ error is within the controllable range compared to the actual results.The process parameters of InCl₃ prepared by metal indium chlorination which can be used in mass production of the factory by thermodynamic calculation,molecular simulation and experiment are as follows:only indium and chlorine are needed in a special horizontal reactor,and the temperature is raised to 650℃ for 3 hours and then condensed.The tube was cooled and collected to obtain a purity of 99.99%,a mass of 51.3 5%,a yield of up to 94.1%,and no water containing InCl₃.This method reduces the water content of the product,shortens the preparation cycle,simplifies the preparation process,saves the cost of the organic solvent,and improves the quality and production of the product compared to other preparation processes method.The above results indicate that the improved metal indium chlorination method can produce InCl₃ with high purity,no water content and high economic value,and has popularization value in industrial production.Thermodynamic calculations and molecular dynamics simulations clearly explain the reaction mechanism and state,and provide theoretical guidance for further improvement and optimization of process parameters.