Aqueous Hydrogen Peroxide pH Control for Olefin Epoxidation
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Solution Overview
Problem
Current hydrogen peroxide solutions for olefin epoxidation with heterogeneous catalysts face challenges in maintaining long-term activity and selectivity, with existing parameters such as reaction temperature and pH not fully optimizing conversion rates.
Innovation Solution
An aqueous hydrogen peroxide solution with a specific pH range dependent on its concentration, optimized between pH 3.45 and 3.76, is used to enhance selectivity and conversion rates without impairing hydrogen peroxide conversion, utilizing the alkylanthraquinone process for production and potentially adjusting pH with acids like nitric acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pH of the hydrogen peroxide solution is increased to improve selectivity, then the selectivity towards oxiranes improves, but the conversion rate of hydrogen peroxide decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pH of the hydrogen peroxide solution within a specific range (pH 3.45-3.76) to simultaneously optimize both selectivity towards oxiranes and conversion rate of hydrogen peroxide. This resolves the contradiction by finding the optimal pH window where both parameters are maximized rather than trading one off for the other.
2Productivity
If the pH of the hydrogen peroxide solution is decreased to improve conversion rate, then the conversion rate of hydrogen peroxide improves, but the selectivity towards oxiranes decreases
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal pH range (3.45-3.76) where the conversion rate is maximized while maintaining high selectivity. By changing the pH parameter to this specific range, both conflicting parameters improve simultaneously rather than requiring a trade-off.
3Manufacturing precision
If purification steps are added to improve the quality of hydrogen peroxide solution, then the selectivity and activity of the catalyst are improved, but the process complexity and cost increase
Solution Approach 1:
The patent extracts and removes the need for complex purification steps by directly using the hydrogen peroxide solution as produced by the alkylanthraquinone process. The invention demonstrates that the crude solution already contains the necessary properties for optimal catalysis, eliminating the need for additional purification equipment and operations.
Solution Approach 2:
The hydrogen peroxide production process itself provides the necessary properties for optimal catalysis. The alkylanthraquinone process naturally produces a solution with the appropriate pH and composition range (pH 3.45-3.76) that is self-sufficient for the epoxidation reaction, requiring no external purification intervention.
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 solution achieves improved selectivity and potentially increased hydrogen peroxide conversion rates by maintaining an optimal pH range, specifically for propylene oxide and epichlorohydrin production, while avoiding costly purification steps.
Implementation Method 1
hydrogen peroxide in the presence of a heterogeneous catalyst to convert an olefin into an oxirane, more particularly to convert propylene into propylene oxide (1,2-epoxypropane) by reaction with hydrogen peroxide
Implementation Method 2
the apparent pH of the hydrogen peroxide solution has an impact on the selectivity when this solution is used for the epoxidation of olefins (such as propylene or allyl chloride) into oxiranes (such as propylene oxide or epichlorohydrin)
Data Source
Figure 1
AI summary
The present invention refers to an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration [H2O2] expressed as % by weight of the solution and an apparent pH of from pHmin to pHmax, such that pHmin = 3.45 - 0.0377 x [H2O2] pHmax = 3.76 - 0.0379 x [H2O2]. The present invention also relates to a process for the preparation of said hydrogen peroxide solution and the use of said solution in a process for the epoxidation of olefins.