Glycol Synthesis via Segmented Silver-Copper Catalysis
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Solution Overview
Problem
Existing methods for producing propylene glycol from trihydric or higher-hydric alcohols, such as glycerol, face challenges with low selectivity and yield due to the formation of by-products and require high reaction pressures or excessive hydrogen when using copper catalysts for dehydration and hydrogenation reactions.
Innovation Solution
A method utilizing a silver catalyst for synthesizing hydroxyketone from polyhydric alcohols and a copper-containing hydrogenation catalyst for converting hydroxyketone to glycol, with both catalysts coexisting in a single reaction system supported on chromium oxide, enhances the yield and selectivity of glycol production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a copper catalyst with both dehydration and hydrogenation ability is used to directly synthesize glycol from polyhydric alcohol, then the reaction can proceed in one system, but by-products are easily formed and yield decreases
Solution Approach 1:
The reaction process is segmented into two distinct steps with separate catalysts: first, silver catalyst for dehydration of polyhydric alcohol to hydroxyketone; second, copper-containing hydrogenation catalyst for converting hydroxyketone to glycol. This segmentation prevents by-product formation while maintaining high yield.
Solution Approach 2:
Hydroxyketone is introduced as an intermediate substance in the reaction pathway. The silver catalyst produces hydroxyketone as an intermediate that is then converted by the copper-containing hydrogenation catalyst, allowing the reaction to proceed through a controlled intermediate stage that improves overall yield.
2Device complexity
If copper catalyst is used for dehydration and hydrogenation reactions, then glycol can be produced in one system, but high reaction pressure is required
Solution Approach 1:
The reaction system is divided into two sequential steps with different pressure requirements. The first dehydration step using silver catalyst occurs under milder pressure conditions, while the second hydrogenation step using copper-containing catalyst operates at controlled pressure, reducing the overall pressure resistance requirements for the reaction apparatus.
3Device complexity
If copper catalyst is used for dehydration and hydrogenation, then glycol synthesis can proceed in one system, but selectivity and yield are insufficient
Solution Approach 1:
The reaction is segmented into two specialized steps: dehydration by silver catalyst and hydrogenation by copper-containing catalyst. Each catalyst is optimized for its specific function, resulting in high selectivity for the desired glycol product without the by-product formation that occurs when a single copper catalyst performs both functions.
4Adaptability or versatility
If multi-step reaction is applied to produce glycol from hydroxyketone, then propylene as raw material is avoided, but the yield is insufficient
Solution Approach 1:
The system uses polyhydric alcohol (such as glycerol) as a self-sufficient raw material that contains both the carbon backbone and oxygen atoms needed for glycol synthesis. The two-step catalytic process efficiently converts this self-sufficient raw material to glycol with high yield, eliminating the need for external hydrogen sources or propylene feedstock.
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 efficient and high-yield production of glycol from trihydric or higher-hydric alcohols, maintaining satisfactory yields even under atmospheric pressure and reducing by-product formation, thereby improving the efficiency of the glycol synthesis process.
Implementation Method 1
a reaction for synthesizing hydroxyketone from polyhydric alcohol by using a silver catalyst
Implementation Method 2
a reaction for synthesizing glycol from the hydroxyketone formed in the reaction described above by using a hydrogenation catalyst
Implementation Method 3
copper-containing hydrogenation catalyst for converting hydroxyketone to glycol
Data Source
AI summary
An object of the invention is to provide a production method that can produce glycol from polyhydric alcohol with high selectivity and in a satisfactory yield. The object is achieved by using a silver catalyst in a reaction for synthesizing hydroxyketone from polyhydric alcohol having adjacent hydroxyl groups, and a hydrogenation catalyst in a reaction for synthesizing glycol from hydroxyketone.