Continuous Pentachloropropane Preparation via Solid Oxide Catalyst
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Solution Overview
Problem
Existing methods for preparing 1,1,1,2,3-pentachloropropane face challenges such as unstable catalysts, difficult separation of products from catalysts, and issues with self-polymerization of raw materials, leading to low product yield and complex purification processes.
Innovation Solution
A continuous preparation method using a solid oxide catalyst in a trickle bed reactor, where 1,1,1,3-tetrachloropropane and chlorine are continuously fed to perform a one-step reaction, simplifying the process and improving catalyst stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If anhydrous FeCl3 catalyst is used for liquid-phase chlorination, then the reaction can proceed, but the catalyst is unstable and can only work for five or six hours
Solution Approach 1:
The patent changes the catalyst from anhydrous FeCl3 to FeCl3·6H2O (hydrated form), altering the physical and chemical parameters of the catalyst. This parameter change results in a catalyst that is stable and reusable for over 100 hours, resolving the instability issue while maintaining catalytic activity
Solution Approach 2:
The patent transitions from a short-lived catalyst (5-6 hours) to a long-lived catalyst (over 100 hours), effectively making the catalyst reusable rather than disposable. This extends the catalyst's service life significantly, improving both reliability and productivity
2Productivity
If trichloropropene is used as raw material, then 1,1,1,2,3-pentachloropropane can be synthesized, but the raw material undergoes self-polymerization resulting in increased by-products and decreased product yield
Solution Approach 1:
The patent introduces 1,1,1,3-tetrachloropropane as an intermediary substance that reacts with chlorine to form the desired product. This intermediary approach avoids the self-polymerization issues of trichloropropene while maintaining efficient product formation, resulting in 98% product yield
Solution Approach 2:
The patent converts the potential harm of raw material polymerization into benefit by selecting a different starting material (1,1,1,3-tetrachloropropane) that does not undergo self-polymerization. This choice transforms the problem into an advantage by enabling higher product yield and simpler purification
3Productivity
If microchannel reactor is used, then mass and heat transfer performance is improved and reaction time is shortened, but solid materials cannot pass through and microchannels are easily blocked by solids
Solution Approach 1:
The patent abandons the microchannel reactor design in favor of a conventional reactor that can handle solid catalysts. While microchannel reactors offer faster reaction rates, their structural limitations with solids make them impractical. The conventional reactor provides a simpler, more robust solution suitable for industrial application
4Productivity
If liquid-phase chlorination is performed with dissolved ferric chloride, then the reaction proceeds, but product separation from catalyst is difficult
Solution Approach 1:
The patent uses solid FeCl3·6H2O catalyst instead of dissolved ferric chloride, creating a heterogeneous reaction system. The solid catalyst can be easily separated from the liquid product through filtration or decantation, solving the separation difficulty while maintaining high reaction efficiency
Solution Approach 2:
The patent employs solid FeCl3·6H2O as an intermediary catalyst that facilitates the reaction but remains in a different phase from the product. This phase difference enables simple separation, improving ease of manufacture while maintaining productivity
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 method achieves high conversion rates (up to 98.4%) and selectivity (up to 98.2%) for 1,1,1,2,3-pentachloropropane, with stable catalyst performance over extended operation times, facilitating continuous and efficient industrial production.
Implementation Method 1
carrying out a reaction in the presence of a solid oxide catalyst to obtain 1,1,1,2,3-pentachloropropane
Data Source
AI summary
Disclosed is a continuous preparation method of 1,1,1,2,3-pentachloropropane, comprising: continuously feeding 1,1,1,3-tetrachloropropane and chlorine into a reactor, respectively, and carrying out a reaction in the presence of a solid oxide catalyst to obtain 1,1,1,2,3-pentachloropropane. The reaction is a gas-liquid-solid three-phase reaction. 1,1,1,3-tetrachloropropane is fed from the top of the reactor, and chlorine is fed from the top or bottom of the reactor. The reaction conditions are mild and the process is simple. In addition, the process also has the advantages of less three wastes, high conversion rate of 1,1,1,3-tetrachloropropane, high product selectivity, stable catalyst performance and continuous production, and has broad industrial application prospects.