Nitrate Salen Catalyst for CO2 Copolymerization
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Solution Overview
Problem
The existing catalysts for polycarbonate production from epoxide compounds and carbon dioxide are unsuitable for mass production due to explosiveness, high costs, and difficulties in catalyst recovery and reuse, particularly due to the use of expensive reagents like AgBF4 and NaH, and the need for dry conditions.
Innovation Solution
A Salen type ligand with three or more quaternary ammonium salts of nitrate anions is used to form a trivalent metal complex catalyst, replacing 2,4-dinitrophenolate with nitrate and acetate anions, allowing for the use of AgNO3 and nitric acid, which reduces costs and simplifies the synthesis and recovery process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If 2,4-dinitrophenolate is used in the catalyst, then high catalytic activity is achieved, but the catalyst becomes explosive and unsuitable for mass production
Solution Approach 1:
The patent replaces the explosive 2,4-dinitrophenolate with nitrate anions that are less hazardous. While the original catalyst provided high activity, it created safety issues. The new catalyst using nitrate anions maintains catalytic function while eliminating the explosive hazard, making it suitable for mass production and continuous use.
2Reliability
If AgBF4 is used in catalyst preparation, then the catalyst structure is formed, but the preparation cost becomes very high
Solution Approach 1:
The patent extracts the essential function of AgBF4 (providing silver ions for complex formation) while replacing the expensive BF4- anion with cheaper nitrate anions. This substitution maintains the catalyst's structural integrity and activity while dramatically reducing the preparation cost, making mass production economically viable.
3Ease of manufacture
If NaH and anhydrous THF are used in catalyst synthesis, then the reaction proceeds, but the process becomes complex and difficult to mass handle
Solution Approach 1:
The patent changes the reaction conditions from requiring strictly anhydrous conditions (NaH in anhydrous THF) to allowing aqueous or less stringent conditions by using nitrate salts. This parameter change eliminates the need for specialized dry handling equipment and procedures, simplifying the process for mass production while maintaining reaction efficiency.
4Power
If 2,4-dinitrophenol group is attached to polymer chain end, then catalyst activity is maintained, but the resin price increases and color changes
Solution Approach 1:
The patent replaces the 2,4-dinitrophenol end group with nitrate-containing groups that do not cause yellow discoloration of the resin. The nitrate group is less harmful to the final product quality, eliminating the pale yellow coloration while maintaining catalyst activity, thus producing higher quality polycarbonate suitable for commercial applications.
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 enables the production of polycarbonate with reduced catalyst costs, facilitates mass production, and allows for efficient separation and reuse of the catalyst, improving the economic viability and scalability of the process.
Implementation Method 1
a method of preparing polycarbonate by copolymerizing an epoxide compound and carbon dioxide using the complex compound as a catalyst
Data Source
AI summary
This invention relates to a Salen type ligand including three or more quaternary ammonium salts of nitrate anions, to a trivalent metal complex compound prepared from this ligand and a method of preparing the same, to a method of preparing polycarbonate by copolymerizing an epoxide compound and carbon dioxide using the complex compound as a catalyst, and to a method of separating and collecting the catalyst from the copolymer after copolymerization. This catalyst used to copolymerize an epoxide compound and carbon dioxide can be more simply prepared, and has lower catalyst preparation and recovery costs, and higher activity, compared to conventional catalysts.