Fluorinated Olefin Synthesis via Metal Fluoride Catalysts
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Solution Overview
Problem
Existing methods for producing fluorinated olefins, such as HFO-1234yf and HFO-1234ze, using mixed metal oxides as catalysts are not suitable due to their tendency to react with hydrofluorocarbons, leading to the formation of undesirable byproducts like 3,3,3-trifluoropropene, which is flammable and difficult to separate, resulting in yield loss during purification.
Innovation Solution
The use of dehydrogenation or oxidative dehydrogenation catalysts comprising Group VIII noble metals supported on metal fluoride or metal oxyfluoride supports, which minimizes the conversion to 3,3,3-trifluoropropene, allowing for the efficient conversion of fluorinated alkanes to tetrafluoropropenes with high selectivity and conversion rates, preferably using reactors with corrosion-resistant materials and specific temperature and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mixed metal oxide catalysts are used for dehydrogenation of fluorinated alkanes, then the conversion to fluorinated olefins can proceed, but the catalyst reacts with hydrofluorocarbons to form metal oxyfluorides or metal fluorides, causing catalyst structure collapse and formation of unwanted byproducts
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst from mixed metal oxides to metal fluorides and metal oxyfluorides. This parameter change prevents the catalyst from reacting with hydrofluorocarbons, maintaining catalyst stability while still achieving effective dehydrogenation conversion of fluorinated alkanes to fluorinated olefins.
Solution Approach 2:
The patent uses composite catalyst systems comprising metal fluorides and metal oxyfluorides, often supported on appropriate materials. These composite structures provide both the catalytic activity needed for dehydrogenation and the chemical stability required to resist reaction with hydrofluorocarbons, resolving the contradiction between productivity and reliability.
2Productivity
If dehydrofluorination catalysts are used to produce HFO-1234yf and HFO-1234ze, then conversion can occur, but the byproduct 3,3,3-trifluoropropene is formed which is flammable and difficult to separate due to azeotropic composition
Solution Approach 1:
The patent optimizes reaction parameters including temperature, pressure, and contact time to favor the formation of desired HFO products over the flammable HFO-1234zf byproduct. By carefully controlling these parameters, the process achieves high conversion while minimizing harmful byproduct formation.
Solution Approach 2:
The patent employs catalysts with specific local properties - metal fluorides and oxyfluorides with particular crystal structures and surface characteristics that provide selectivity for the desired dehydrogenation pathway while suppressing dehydrofluorination that leads to the flammable byproduct.
3Productivity
If conventional catalysts are used, then dehydrogenation can proceed, but the catalyst structure collapses due to conversion of metal oxides into metal oxyfluorides or metal fluorides
Solution Approach 1:
The patent fundamentally changes the catalyst composition from metal oxides to metal fluorides and metal oxyfluorides. This compositional parameter change ensures that the catalyst structure remains stable under reaction conditions, as these materials are resistant to further fluorination and structural collapse while maintaining catalytic activity for dehydrogenation.
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 high conversion rates (up to 90%) and selectivity (up to 95%) for producing HFOs while substantially limiting the formation of 3,3,3-trifluoropropene, thereby improving the purity and yield of desired products like HFO-1234yf and HFO-1234ze.
Implementation Method 1
converting at least one compound of formula (I) to at least one compound of formula (II) wherein the converting step comprises exposing said compound of formula (I) to a dehydrogenation catalyst or combination of dehydrogenation catalysts
Implementation Method 2
converting at least one compound of formula (I) to at least one compound of formula (II) wherein the converting step comprises exposing said compound of formula (I) to an oxidative dehydrogenation catalyst or combination of oxidative dehydrogenation catalysts
Data Source
AI summary
A method of converting a first reaction stream comprising at least one pentafluoropropene to a final product stream comprising at least one compound of formula (II): CHX=CZCF3 (II) wherein X and Z are each independently H or F, with the proviso that X and Z are not the same, comprising processing said first reaction stream under conditions effective to convert said at least one pentafluoropropene to at least one compound of formula (II); wherein said processing step comprises: (a) reacting said at least one pentafluoropropene to obtain a first product stream comprising at least one pentafluoropropane and at least one compound of formula (I): CH2XCHZCF3 (I) wherein X and Z are each independently H or F, with the proviso that X and Z are not the same; (b) separating said at least one compound of formula (I) from said first product stream to obtain a separated product stream and a second reaction stream, wherein said separated product stream comprises a higher weight percent of said at least one compound of formula (I) than said second reaction stream; and (c) reacting said second reaction stream under conditions effective to produce said at least one compound of formula (II).