Simultaneous Fluoroolefin Synthesis via Gas Phase Catalyst
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Solution Overview
Problem
Current methods for preparing 1,1,1,2-tetrafluoropropene are inefficient due to the high cost of raw materials, generation of side products, decreased selectivity at high reaction temperatures, and difficulties in commercially applying processes with by-product handling.
Innovation Solution
A method involving the simultaneous preparation of 1,1,1-trifluoro-2-chloropropene and 1,1,1,2-tetrafluoropropene using a gas phase catalyst in a single reactor, where 1,1,1,3-tetrachloropropane is used as a cheaper raw material, and dehydrochlorination is performed at elevated temperatures with a supported metal catalyst, followed by washing and distillation to enhance conversion and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential hydrogenation and dehydrofluorination steps are used to prepare 1,1,1,2-tetrafluoropropene from HFP, then the product can be obtained through known methods, but the raw material cost is high and side reaction products are generated
Solution Approach 1:
The invention segments the reaction process by using two different catalysts in separate reactors: a first catalyst (Pd, Pt, or Rh supported on activated carbon) for dehydrochlorination to produce 1,1,1-trifluoro-2-chloropropene, and a second catalyst (Al2O3, SiO2, or TiO2 supported on activated carbon) for subsequent dehydrofluorination to produce 1,1,1,2-tetrafluoropropene. This segmentation allows each reaction step to be optimized independently, improving overall efficiency and reducing side products
Solution Approach 2:
The invention introduces 1,1,1-trifluoro-2-chloropropene as an intermediate compound that serves as a bridge between the starting material (1,1,1,3,3,3-hexafluoropropene) and the final product (1,1,1,2-tetrafluoropropene). This intermediary approach allows for better control of the reaction pathway and reduced formation of unwanted side products compared to direct transformation methods
2Productivity
If pyrolysis at high reaction temperature (460-620°C) without catalyst is used, then 1234yf can be prepared, but the selectivity of 1234yf decreases over reaction time due to fluorination and chlorination of reactor wall surface
Solution Approach 1:
The invention introduces a catalyst as an intermediary substance that facilitates the dehydrochlorination reaction at lower temperatures (200-400°C). The catalyst (first catalyst for dehydrochlorination, second catalyst for dehydrofluorination) provides an alternative reaction pathway that avoids the need for high-temperature pyrolysis, thereby preventing wall surface fluorination and chlorination while maintaining high selectivity
Solution Approach 2:
The invention changes the temperature parameter from high-temperature pyrolysis (460-620°C) to moderate-temperature catalytic reactions (200-400°C). This parameter change, combined with the introduction of catalysts, enables the reaction to proceed efficiently without causing wall surface contamination, thus maintaining high selectivity over time
3Reliability
If phase transfer catalyst and KOH/NaOH are used for dehydrochlorination at 50°C and 12-13 barg pressure, then 1234yf can be prepared, but the reaction time is long and KCl by-product processing is required
Solution Approach 1:
The invention employs gas-phase reactants and products that flow through the catalyst bed in a continuous process. The use of gaseous 1,1,1,3,3,3-hexafluoropropene and chlorine gas, along with gaseous product removal, enables faster reaction kinetics and continuous processing compared to liquid-phase methods, reducing both reaction time and by-product handling requirements
Solution Approach 2:
The invention changes the physical state parameters from liquid-phase reaction at 50°C and 12-13 barg pressure to gas-phase reaction at 200-400°C and atmospheric or slightly elevated pressure. This parameter change enables faster reaction rates, continuous processing, and eliminates the formation of solid KCl by-products that require additional processing
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 method achieves superior conversion rates and selectivity for 1,1,1,2-tetrafluoropropene while reducing costs and side product generation, enabling a commercially viable continuous process.
Implementation Method 1
a method of simultaneously preparing 1,1,1-trifluoro-2-chloropropene and 1,1,1,2-tetrafluoropropene with high efficiency using the same gas phase catalyst
Implementation Method 2
performing dehydrochlorination while maintaining the temperature of the reactor
Implementation Method 3
using a supported metal catalyst
Implementation Method 4
followed by washing and distillation to enhance conversion and selectivity
Data Source
AI summary
Disclosed is a method of simultaneously preparing 1,1,1-trifluoro-2-chloropropene and 1,1,1,2-tetrafluoropropene, the method including i) a step of elevating a temperature of a reactor charged with a gas phase catalyst up to a reaction temperature; ii) a step of feeding 1,1,1-trifluoro-2,3-dichloropropane and 2-chloro-1,1,1,2-tetrafluoropropane into the reactor, the temperature of which has been elevated; iii) a step of performing dehydrochlorination while maintaining the temperature of the reactor; and iv) a step of performing washing and distillation after the dehydrochlorination. In accordance with the present disclosure, a high-efficient gas-phase process of continuously, simultaneously preparing 1,1,1-trifluoro-2-chloropropene and 1,1,1,2-tetrafluoropropene is provided.