DMC Catalyst Additives for Faster Polyether Polymerization
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Solution Overview
Problem
Double metal cyanide catalysts exhibit latency and sluggish performance in high hydroxyl group concentrations, particularly in low molecular weight product production and semi-batch processes, necessitating improved catalyst systems for efficient alkylene oxide polymerization.
Innovation Solution
A catalyst complex comprising a cyanometallate compound and a specific M 1< metal compound, combined with an additive such as alkali metal or ammonium salts, enhances catalyst activation and polymerization rates, especially in the presence of high hydroxyl concentrations, allowing ethylene oxide polymerization onto low molecular weight starters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMC catalysts are used for alkylene oxide polymerization, then polymerization selectivity is improved and unwanted monofunctional polymers are reduced, but polymerization rate is reduced due to latency and sluggish performance
Solution Approach 1:
The patent introduces an intermediary substance (a compound containing a specific functional group) that mediates between the DMC catalyst and the alkylene oxide monomer. This intermediary facilitates faster catalyst activation and enhances polymerization rate while preserving the selectivity benefits of DMC catalysts, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent modifies the catalyst system by changing chemical parameters - specifically incorporating a compound with a functional group that alters the catalyst's activation kinetics. This parameter change enables the DMC catalyst to achieve both high selectivity and enhanced activity, eliminating the latency period and improving polymerization rate.
2Stability of the object's composition
If DMC catalysts are used in high hydroxyl group concentration conditions, then catalyst stability is maintained, but polymerization activity is significantly reduced
Solution Approach 1:
The intermediary compound acts as a bridge that allows the DMC catalyst to function effectively in high hydroxyl group concentration environments. It protects the catalyst from deactivation by hydroxyl groups while maintaining catalytic activity, thus resolving the contradiction between stability and productivity under these conditions.
Solution Approach 2:
The patent creates a modified catalyst system that replicates the stable characteristics of DMC catalysts in high hydroxyl environments while copying the enhanced activity through the intermediary compound's catalytic contribution, achieving both stability and high activity simultaneously.
3Adaptability or versatility
If low molecular weight starters are used, then product versatility is improved, but catalyst performance becomes sluggish
Solution Approach 1:
The patent changes the catalyst system parameters by introducing the intermediary compound, which alters the activation energy and reaction kinetics. This enables the catalyst to maintain high performance even when working with low molecular weight starters, thus resolving the contradiction between versatility and productivity.
4Productivity
If additional catalyst components are added to improve catalyst performance, then polymerization rate is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the DMC catalyst system with a single intermediary compound in a unified catalyst formulation. This combining approach enhances polymerization rate while avoiding the complexity of multiple separate catalyst components, as the intermediary integrates seamlessly with the DMC catalyst system.
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 catalyst system significantly improves polymerization rates and molecular weight control, producing polyethers with controlled molecular weight and low polydispersities, even under stringent conditions.
Implementation Method 1
They are important raw materials for producing polyurethanes and are used as surfactants and industrial solvents, among other uses. The predominant polymerization catalysts are alkali metal hydroxides or alkoxides and certain metal complexes that are commonly referred to as double metal cyanide (DMC) catalysts.
Data Source
AI summary
Alkylene oxides are polymerized in the presence of a catalyst system that includes a double metal cyanide catalyst that is modified with certain metal or semi-metal compounds. At least one additive is present. The additive is an alkali metal, ammonium or quaternary ammonium salt of a monocarboxylic acid having up to 24 carbon atoms; monobasic potassium phosphate, a monobasic ammonium or quaternary ammonium phosphate, a dibasic ammonium and quaternary ammonium phosphate or phosphoric acid.