HFC-1234ze Dehydrofluorination Catalysts for E-Isomer Selectivity
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Solution Overview
Problem
Existing manufacturing processes for producing HFC-1234ze and HFC-1234yf, which are refrigerants with zero ozone depletion and low global warming potential, are inefficient and require additional steps to separate and convert the Z-isomer to the more useful E-isomer, increasing costs.
Innovation Solution
A gas-phase dehydrofluorination process using a catalyst such as fluorinated Cr2O3 or Cr/Ni on fluorided alumina to convert a mixture of 1,1,1,3,3-pentafluoropropane and Z-1,3,3,3-tetrafluoropropene, selectively producing E-1,3,3,3-tetrafluoropropene by suppressing the formation of the Z-isomer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalytic vapor phase dehydrofluorination is used to produce HFC-1234ze, then the production of E- and Z-isomers occurs, but the Z-isomer formation (15-23%) requires additional costly separation and isomerization steps
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by introducing a specific catalyst composition (chromium oxide with promoters such as nickel, cobalt, or zinc) and controlling reaction conditions (temperature, pressure, feed composition) to shift the isomer distribution ratio toward the desired E-isomer, thereby reducing Z-isomer formation and eliminating the need for additional separation steps
Solution Approach 2:
The patent implements a feedback mechanism by recycling the Z-isomer product back to the reactor along with fresh feedstock, allowing it to be converted to the E-isomer through the catalytic action, thereby continuously improving the E-isomer yield and reducing waste
2Manufacturing precision
If traditional dehydrofluorination catalysts are used, then E- and Z-isomers are produced in a mixture, but additional separation and isomerization steps are required increasing costs
Solution Approach 1:
The patent modifies the catalyst parameters by using chromium oxide as the base catalyst with specific promoters (nickel, cobalt, zinc) and controlling the atomic ratios and physical state of the catalyst to achieve high selectivity for the E-isomer, thereby reducing manufacturing costs by eliminating additional separation steps
Solution Approach 2:
The patent converts the previously harmful Z-isomer byproduct into a useful resource by recycling it back to the reactor where it is converted to the desired E-isomer through catalytic action, thereby eliminating waste and reducing raw material requirements
3Reliability
If Z-isomer is separated and isomerized to E-isomer in a separate step, then pure E-isomer is obtained, but additional steps add cost and reduce efficiency
Solution Approach 1:
The patent merges the separation and isomerization steps into a single catalytic conversion process, where the Z-isomer is directly converted to the E-isomer in the reactor along with the fresh feedstock, thereby simplifying the process and improving efficiency while maintaining high E-isomer purity
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
The process achieves high selectivity and yield of E-1,3,3,3-tetrafluoropropene, minimizing the need for additional separation or conversion steps, thereby reducing production costs and improving efficiency.
Implementation Method 1
contacting a mixture of 1,1,1,3,3-pentafluoropropane and Z-1,3,3,3-tetrafluoropropene in the gas phase with a catalyst comprising at least one catalyst selected from the group consisting of fluorinated Cr2O3 or Cr/Ni on fluorided alumina
Data Source
AI summary
A method of producing a fluoropropene of formula CF3CH=CHF, comprising contacting a mixture of 1,1,1,3,3-pentafluoropropane and Z-1,3,3,3-tetrafluoropropene in the gas phase with a catalyst comprising at least one catalyst selected from the group consisting of fluorinated Cr2O3 or Cr/Ni on fluoride alumina, in the presence of an oxygen containing gas, to form a mixture comprising Z-1,3,3,3-tetrafluoropropane, E-1,3,3,3-tetrafluoropropene, hydrogen fluoride, and optionally unreacted 1,1,1,3,3-pentafluoropropane, separating the E-1,3,3,3-tetrafluoropropene from the Z-isomer and any unreacted 1,1,1,3,3-pentafluoropropane, if present, and recovering said E-1,3,3,3-tetrafluoropropene.