Preheating Hydrofluoric Acid to Reduce By-Products in Fluorination
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Solution Overview
Problem
The production of trans-1-chloro-3,3,3-trifluoropropene is hindered by the formation of by-products and superfluorinated products due to high reactor temperatures, leading to complex and costly purification processes and significant losses of the desired product.
Innovation Solution
Preheating hydrofluoric acid to a temperature significantly higher than the reaction temperature allows for a controlled reaction at a lower reactor temperature, minimizing by-product formation and optimizing the production of trans-1-chloro-3,3,3-trifluoropropene by maintaining a temperature difference of at least 30°C between the preheated acid and the reaction mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fluorination reaction is carried out at high temperature to ensure reaction rate, then the reaction proceeds efficiently, but by-products such as cis-1-chloro-3,3,3-trifluoropropene and over-fluorinated products are significantly increased
Solution Approach 1:
The hydrofluoric acid is preheated to a temperature significantly higher than the reaction temperature (T1 - T2 ≥ 30°C) before being introduced into the reactor. This preliminary heating ensures that the reagent is sufficiently active to drive the fluorination reaction at the desired lower temperature, thereby maintaining reaction efficiency while minimizing by-product formation.
Solution Approach 2:
The invention changes the temperature parameter of the hydrofluoric acid reagent separately from the reactor temperature. By controlling the reagent temperature (T1) to be significantly higher than the reaction temperature (T2), the process achieves efficient fluorination at lower reactor temperatures, thus reducing cis-isomer and over-fluorinated by-products while maintaining productivity.
2Manufacturing precision
If the reactor temperature is maintained high to ensure complete fluorination, then the conversion is efficient, but the production of over-fluorinated products such as 1,1,1,3,3-pentafluoropropane increases
Solution Approach 1:
The invention decouples the reagent temperature from the reactor temperature by preheating the hydrofluoric acid to T1 (where T1 - T2 ≥ 30°C). This parameter change allows the reaction to proceed with high conversion efficiency at a controlled reactor temperature T2, preventing excessive fluorination and the formation of over-fluorinated by-products.
3Device complexity
If simple distillation is used to separate HCFO-1233zdE from by-products, then the purification process is simple, but separation is very difficult or impossible due to azeotropic compound formation
Solution Approach 1:
The invention performs preliminary action by controlling the reaction conditions (preheating HF to T1 ≥ T2 + 30°C and maintaining reactor at T2) to minimize the formation of by-products at the source. This preventive approach reduces the complexity of subsequent purification steps and avoids the need for complex separation processes to handle azeotropic mixtures.
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 process reduces the production of unwanted by-products and superfluorinated compounds, enhancing the efficiency and yield of trans-1-chloro-3,3,3-trifluoropropene while minimizing energy consumption and purification costs.
Implementation Method 1
supply of a current B comprising hydrofluoric acid heated to a temperature T1 between 100°C and 170°C
Implementation Method 2
the temperature difference, in absolute value, between said temperature T1 and said temperature T2 is greater than or equal to 30°C
Implementation Method 3
reaction in said liquid phase A of said current B with said current C to form a current D comprising trans-1-chloro-3,3,3-trifluoropropene
Data Source
AI summary
The present invention relates to a process for the production of trans-1-chloro-3,3,3-trifluoropropene, comprising the steps of: i) providing a reactor comprising a cover, a bottom, sidewalls connecting said bottom and said cover, at least one reagent supply line and at least one line for drawing off the formed products, said reactor further containing a liquid phase A; ii) providing a stream B comprising hydrofluoric acid heated at a temperature T1 of 100 °C to 170 °C and providing a stream C comprising 1,1,3,3-tetrachloropropene and/or 1,3,3,3-tetrachloropropene; said stream B and said stream C supplying said reactor via said at least one reagent supply line; iii) reacting in said liquid phase A said stream B with said stream C in order to form stream D comprising trans-1-chloro-3,3,3-trifluoropropene. The invention is characterized in that step iii) is carried out at a temperature T2 of between 50 °C and 110 °C, and the temperature difference in absolute values between said temperature T1 and said temperature T2 is greater than 30 °C.