Chromium Oxyfluoride Catalyst for HFC-125 Production
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Solution Overview
Problem
Conventional production methods using chromium-based catalysts for producing pentafluoroethane (HFC-125) from tetrachloroethylene result in undesirable by-products, catalyst deterioration, and decreased catalytic activity, requiring complex separation processes and increased costs.
Innovation Solution
A method involving the use of chromium oxyfluoride as a catalyst and feeding oxygen at a specific range of 0.4-1.8% by mole with tetrachloroethylene in a gas phase fluorination reaction, maintaining high catalytic activity and selectivity of HFC-125 while reducing by-product formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen is added to suppress catalyst deterioration, then catalyst activity is maintained, but by-products increase and selectivity decreases
Solution Approach 1:
The patent changes the chemical composition parameter of the catalyst from chromium oxide to chromium oxyfluoride, and optimizes the oxygen concentration parameter to 0.01-5% by mole. This combination of parameter changes allows maintaining catalyst activity while suppressing by-product formation, as the chromium oxyfluoride catalyst has different chemical properties that reduce unwanted oxygen reactions.
Solution Approach 2:
The patent uses a composite catalyst system consisting of chromium oxyfluoride supported on a carrier material. This composite structure provides both the catalytic activity needed for fluorination and the stability to prevent by-product formation, resolving the contradiction between maintaining activity and reducing harmful by-products.
2Duration of action of stationary object
If oxygen is added to maintain catalytic activity, then reaction continues, but separation process becomes complex
Solution Approach 1:
By changing the catalyst composition to chromium oxyfluoride and controlling oxygen concentration within 0.01-5% by mole, the patent achieves long-duration catalytic activity without generating significant by-products that would complicate separation. The parameter optimization ensures clean reaction products that can be separated simply.
3Ease of manufacture
If conventional chromium oxide catalyst is used, then production is simple, but catalyst deteriorates and activity decreases
Solution Approach 1:
The patent modifies the catalyst composition parameter from chromium oxide to chromium oxyfluoride, which fundamentally changes the catalyst's stability and activity characteristics. This parameter change maintains production simplicity while dramatically improving catalyst reliability and preventing deterioration over time.
Solution Approach 2:
The patent employs a composite catalyst material (chromium oxyfluoride on carrier) that combines the ease of manufacture of conventional catalysts with superior stability and longevity. The composite structure provides both simplicity in production and high reliability in long-term operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves a high conversion ratio of PCE and suppresses catalyst deterioration, maintaining selectivity and catalytic activity over a long period, simplifying the separation process and reducing by-product formation.
Implementation Method 1
tetrachloroethylene (PCE) is reacted with HF in a gas phase in the presence of a catalyst (hereinafter, the reaction is also referred to as a 'fluorination reaction') to obtain pentafluoroethane (HFC-125), characterized in that chromium oxyfluoride is disposed in a reactor as the catalyst
Implementation Method 2
oxygen reacts with hydrogen chloride, which is produced by the fluorination reaction, to produce water and chorine (oxychlorination: O2+4HCl→2H2O+2Cl2)
Data Source
AI summary
The present invention aims in a method wherein tetrachloroethylene (PCE) is reacted with HF in a gas phase in the presence of a catalyst to obtain pentafluoroethane (HFC-125), to reduce production of undesirable by-products and maintain a catalytic activity at a high level over a long period of time while achieving a high conversion ratio of PCE and suppressing deterioration of the catalyst.In a method for producing pentafluoroethane wherein tetrachloroethylene is reacted with HF in a gas phase in the presence of a catalyst to obtain pentafluoroethane, characterized in that chromium oxyfluoride is disposed in a reactor as the catalyst, and oxygen is fed into the reactor together with tetrachloroethylene and HF, at a amount of 0.4-1.8% by mole with respect to tetrachloroethylene.