Acrylonitrile Dimer Catalyst Separation via Recrystallization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for preparing acrylonitrile dimers using phosphorus-based catalysts face challenges in efficiently separating the catalyst from the dimerized reactants, leading to low recycling rates and yields due to azeotropic problems and heat-induced side reactions.
Innovation Solution
A method involving pre-separation of the phosphorus-based catalyst from dimerized reactants using recrystallization, followed by distillation to separate the remaining reactants, thereby preventing catalyst decomposition and suppressing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a distillation method is used to separate the phosphorus-based catalyst from dimerized reactants, then the catalyst can be separated based on boiling point differences, but heat application causes continuous side reactions of acrylonitrile dimerized products to produce acrylonitrile trimers and polymers, thereby lowering the yield of acrylonitrile dimer
Solution Approach 1:
The separation process is divided into two distinct stages: first, cooling the reaction mixture to crystallize and separate the phosphorus-based catalyst from the dimerized reactants; second, applying distillation to separate the remaining components. This segmentation allows the catalyst separation to occur under low-temperature conditions that prevent side reactions, while distillation is applied only after catalyst removal to separate the desired product.
Solution Approach 2:
The catalyst separation is performed as a preliminary action before the distillation step. By cooling the reaction mixture first, the phosphorus-based catalyst crystallizes and can be removed by filtration. This preliminary separation prevents the catalyst from being present during subsequent heating and distillation operations, thereby eliminating the risk of heat-induced side reactions that would otherwise occur during catalyst separation.
2Productivity
If a phosphorus-based catalyst is used to increase acrylonitrile dimer yield, then dimerization efficiency improves, but separation of the catalyst from the mixed solvent and dimer becomes difficult due to azeotropic problems, thereby lowering the recycling rate of the catalyst
Solution Approach 1:
The separation method exploits the phase transition of the phosphorus-based catalyst from dissolved state to crystalline solid state by cooling the reaction mixture. This phase transition allows the catalyst to be separated from the liquid mixture of dimer and solvent through simple filtration, avoiding the need to break azeotropic mixtures and enabling easy catalyst recycling.
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 approach simplifies the catalyst separation process, enhances the reuse rate of the phosphorus-based catalyst, and significantly increases the yield of acrylonitrile dimers by avoiding heat-induced decomposition and side reactions.
Implementation Method 1
the acrylonitrile monomer may be dimerized using a ruthenium (Ru)-based compound, a cobalt (Co)-based compound, a phosphorus (P)-based compound, or the like, as a catalyst, thereby producing an acrylonitrile dimer
Implementation Method 2
cooling the dimerized reactants to crystallize the phosphorus-based catalyst
Data Source
AI summary
Provided is a method of preparing an acrylonitrile dimer including: supplying an acrylonitrile monomer, a phosphorus-based catalyst, and an alcohol solvent to a reactor to perform a dimerization reaction to produce dimerized reactants (S10); cooling the dimerized reactants to crystallize the phosphorus-based catalyst (S20); separating the crystallized phosphorus-based catalyst (S30); and supplying the dimerized reactants from which the phosphorus-based catalyst is separated to a distillation column to separate the acrylonitrile dimer (S40).