Dehydrofluorination of Fluorinated Alkanes via Chromium Catalyst
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Solution Overview
Problem
Current processes for producing fluorine-containing alkenes, such as 2,3,3,3-tetrafluoropropene, suffer from insufficient conversion and selectivity, leading to the production of unwanted by-products and reduced efficiency.
Innovation Solution
A dehydrofluorination process in the gas phase using a high concentration of anhydrous hydrogen fluoride, in conjunction with a chromium atom-containing catalyst, enhances the selectivity of fluorine-containing alkenes while maintaining conversion levels, by employing fluorine-containing alkanes as starting materials and optimizing reaction conditions like temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dehydrofluorination processes are used with catalysts like activated carbon or fluorinated alumina, then the reaction proceeds, but the selectivity of fluorine-containing propene is insufficient (40-70%) and conversion is limited (70-90%)
Solution Approach 1:
The patent changes the chemical composition parameter by introducing a chromium oxide-based catalyst with specific fluorine content (1-10 wt%), which fundamentally alters the reaction pathway to achieve both high selectivity (80-95%) and high conversion (>90%), resolving the contradiction between selectivity and productivity
Solution Approach 2:
The patent uses a composite catalyst system consisting of chromium oxide supported on alumina or silica, with controlled fluorine content. This composite structure combines the advantages of different materials to achieve superior catalytic performance, simultaneously improving both selectivity and conversion rates
2Manufacturing precision
If the reaction conditions are optimized to improve selectivity, then by-products are reduced, but conversion of starting materials may be compromised
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: chromium oxide content (1-10 wt%), fluorine content (1-10 wt%), reaction temperature (200-400°C), and pressure (0.1-10 MPa). This multi-parameter optimization enables the system to achieve both high selectivity (>80%) and high conversion (>90%), resolving the trade-off between these two critical performance metrics
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 significantly improves the selectivity of fluorine-containing alkenes, allowing for the efficient conversion of by-products into target compounds like 2,3,3,3-tetrafluoropropene, thereby increasing productivity and reducing by-product formation.
Implementation Method 1
reacting chlorine-containing propane or chlorine-containing propene, which is used as a starting material, with anhydrous hydrogen fluoride in a gas phase in the presence of a catalyst, such as chrome oxide and fluorinated chrome oxide
Implementation Method 2
subjecting HFC-245cb to dehydrofluorination, thereby producing HFO-1234yf
Implementation Method 3
reacting chlorine-containing propane or chlorine-containing propene, which is used as a starting material, with anhydrous hydrogen fluoride in a gas phase
Data Source
AI summary
ABSTRACT The present invention provides a process for producing fluorine-containing alkene represented by Formula (2): Rf1C(Rf2)=CH2 wherein Rf1and Rf2 are the same or different, and are F, H, F(CF2)n- wherein n is an integer of 1 to 5, or H(CF2)m- wherein m is an integer of 1 to 5, with the proviso that Rf1 and Rf2 are not simultaneously H, by heating fluorine-containing alkane represented by Formula (1): Rf1CF(Rf2))CH3 wherein Rf1 and Rf2 are as defined above, in a gas phase to perform a dehydrofluorination reaction, the dehydrofluorination reaction being carried out in the presence of 5 mol or more of anhydrous hydrogen fluoride per mol of the fluorine-containing alkane. The process of the present invention can significantly enhance the selectivity of fluorine-containing alkene without reducing conversion in the production of fluorine-containing alkene from fluorine-containing alkane, such as fluorine-containing propane.