Double Metal Cyanide Catalyst Activation with Magnesium Compounds
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Solution Overview
Problem
Double metal cyanide (DMC) catalysts face challenges such as slow activation, high costs, poor performance in high hydroxyl group concentrations, and production of high molecular weight polymers, limiting their use in commercial-scale production of low hydroxyl equivalent weight polyether polyols and flexible polyurethane foams.
Innovation Solution
Incorporating a magnesium, Group 3-Group 15 metal or lanthanide series compound bonded to alkoxide, aryloxy, or carboxylate anions into the polymerization process with DMC catalysts to enhance catalyst activation, reduce catalyst usage, and improve polymerization rates, especially in high hydroxyl group environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If DMC catalyst complexes are used for polymerization, then catalyst residues can be left in the product without neutralization and purification, but the catalyst activates slowly requiring long induction periods that reduce productivity
Solution Approach 1:
The patent introduces a metal alkoxide compound as an intermediary substance that mediates between the DMC catalyst and the alkylene oxide monomer. The metal alkoxide activates the DMC catalyst to form a more active species that can rapidly polymerize the monomer, thereby reducing the induction period while maintaining the advantage of eliminating neutralization steps
Solution Approach 2:
The patent changes the chemical state and concentration parameters by adding metal alkoxide compounds at specific concentrations (0.01-10 wt% relative to DMC catalyst). This parameter change transforms the catalyst system from a slow-activating state to a rapidly polymerizing state, resolving the contradiction between ease of manufacture and productivity
2Manufacturing precision
If DMC catalyst complexes are used, then polyether products with low polydispersity can be produced, but the high cost of the catalyst limits its use to very small quantities which are insufficient for economical polymerization rates
Solution Approach 1:
The metal alkoxide acts as a mediator that amplifies the catalytic activity of the DMC complex. By forming a more active catalytic species, a smaller amount of expensive DMC catalyst can achieve the same polymerization rate that would otherwise require much larger amounts of catalyst, thus maintaining both precision and productivity
Solution Approach 2:
The patent optimizes the concentration ratio between metal alkoxide and DMC catalyst to achieve maximum catalytic efficiency. This parameter optimization allows using minimal DMC catalyst (maintaining low cost) while achieving high polymerization rates and controlled polydispersity
3Adaptability or versatility
If DMC catalysts are used in the presence of high concentrations of hydroxyl groups, then polyether polyols with low hydroxyl equivalent weights can be produced, but the catalyst performance deteriorates significantly
Solution Approach 1:
The metal alkoxide compound serves as a protective intermediary that shields the DMC catalyst from deactivation by hydroxyl groups. The metal alkoxide forms a stable complex with the catalyst that resists interference from high concentrations of hydroxyl groups, enabling reliable catalyst performance in producing low hydroxyl equivalent weight polyols
Solution Approach 2:
The patent introduces metal alkoxide compounds that change the chemical environment around the catalyst, creating a protective sphere that excludes interfering hydroxyl groups. This parameter change in the local chemical environment maintains catalyst reliability even in high hydroxyl concentration conditions
4Ease of manufacture
If DMC catalyst complexes are used, then production costs can be reduced by eliminating neutralization steps, but the long catalyst induction period results in loss of productivity and potential batch abandonment
Solution Approach 1:
The metal alkoxide intermediary accelerates catalyst activation so rapidly that the induction period becomes negligible. This eliminates the risk of batch abandonment due to prolonged induction while maintaining the cost advantage of eliminating neutralization steps
Solution Approach 2:
The metal alkoxide is added beforehand to the catalyst system to pre-activate it before monomer addition. This preliminary action ensures the catalyst is fully activated and ready for immediate high-rate polymerization, preventing productivity losses from long induction periods
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 significantly reduces catalyst activation times, allows for low DMC catalyst concentrations, and prevents the formation of high molecular weight polymers, enabling efficient production of polyether polyols across a wide range of hydroxyl equivalent weights, including those below 400, with improved productivity and cost-effectiveness.
Implementation Method 1
Incorporating a magnesium, Group 3-Group 15 metal or lanthanide series compound bonded to alkoxide, aryloxy, or carboxylate anions into the polymerization process with DMC catalysts to enhance catalyst activation
Implementation Method 2
a magnesium, Group 3-Group 15 metal or lanthanide series metal compound in which a magnesium, Group 3-Group 15 or lanthanide series metal is bonded to at least one alkoxide, aryloxy, carboxylate, acyl, pyrophosphate, phosphate, thiophosphate, dithiophosphate, phosphate ester, thiophosphate ester, amide, siloxide, hydride, carbamate or hydrocarbon anion
Data Source
AI summary
Alkylene oxide polymerizations are performed in the presence of a double metal cyanide polymerization catalyst and certain magnesium, Group 3-Group 15 metal or lanthanide series metal compounds. The presence of the magnesium, Group 3-Group 15 metal or lanthanide series metal compound provides several benefits including more rapid catalyst activation, faster polymerization rates and the reduction in the amount of ultra high molecular weight polymers that are formed. The catalyst mixture is unexpectedly useful in making polyethers having low equivalent weights.