Manganese Catalyst Bleaching at High pH With Low Catalyst Loading
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Solution Overview
Problem
Current methods for bleaching cellulosic substrates and treating effluent waste streams require high levels of manganese transition metal catalysts, which can be costly and inefficient, especially at optimal pH ranges for manganese complex effectiveness.
Innovation Solution
A method using a preformed manganese transition metal catalyst in an aqueous medium with hydrogen peroxide at high pH (11-13) to achieve effective bleaching with minimal catalyst levels, specifically employing dinuclear Mn(II)Mn(II), Mn(II)Mn(III), Mn(III)Mn(III), Mn(III)Mn(IV), or Mn(IV)Mn(IV) complexes with 1,2-bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)-ethane (Me4-DTNE) as a ligand, and counter ions like PF6− or ClO4− for water solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high levels of manganese transition metal catalyst are used for bleaching, then effective bleaching is achieved, but cost and inefficiency increase
Solution Approach 1:
The patent changes the pH parameter to highly alkaline conditions (pH 12-13) where the manganese catalyst exhibits maximum activity. This parameter change allows the catalyst to work much more efficiently, achieving effective bleaching at extremely low concentrations (0.0001-1.5 microM) compared to conventional methods that require high catalyst levels.
Solution Approach 2:
The patent uses a preformed dinuclear manganese catalyst complex that is already in the active configuration before contact with the substrate. This preliminary preparation of the catalyst in its optimal dinuclear form ensures maximum catalytic activity from the start, eliminating the need for high concentrations to achieve effective bleaching.
2Reliability
If optimal pH ranges (10.0-11.0) are used for manganese complex effectiveness, then catalyst activity is maximized, but bleaching efficiency at high pH (11-13) with minimal catalyst levels is not achieved
Solution Approach 1:
The patent extends the pH optimization to a higher alkaline range (pH 11-13, preferably 12-13) than previously reported. This parameter change reveals that the dinuclear manganese catalyst maintains high activity and stability in this extended pH range, enabling both optimal catalyst activity and high bleaching efficiency with minimal catalyst levels simultaneously.
Solution Approach 2:
The patent employs a dinuclear manganese catalyst complex with a specific ligand structure (Me3-TACN or Me4-DTNE) that creates a composite material with enhanced stability and activity at high pH. This composite structure allows the catalyst to withstand and utilize the highly alkaline environment, achieving superior performance that neither component could achieve alone.
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 allows for significant bleaching effects at very low catalyst concentrations (0.0005-1.5 microM), enhancing brightness and whiteness of substrates like softwood and eucalyptus pulp, and raw cotton, even at low pH levels, demonstrating efficient and cost-effective bleaching.
Implementation Method 1
contacting the substrate with an aqueous medium, having at least 1% of water and from 1 to 1500 mM of hydrogen peroxide, to form an oxidative medium, the aqueous medium comprising a transition metal catalyst
Implementation Method 2
oxidative medium has a pH in the range 11 to 13...oxidations of alkenes into epoxides and/or diols and/or dicarboxylic acids, alcohol into aldehyde and/or carboxylic acids
Data Source
AI summary
The present invention concerns the treatment of substrates with a preformed transition metal catalyst in an aqueous solution. The transitional metal catalyst is a dinuclear Mn transitional metal catalyst and its ligand has the following formula (I):and p is 3.