Cobalt Catalyst Stability in Diol Hydrogenation via Alkali Ion Control
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Solution Overview
Problem
Cobalt-containing catalysts used for hydrogenating carboxylic acids and their derivatives are unstable in acidic conditions, leading to reduced catalyst life and yield of desired diols due to side reactions such as dehydration and etherification, which require additional purification steps.
Innovation Solution
Incorporating alkali metal and alkaline earth metal ions, excluding mineral acid salts, into the hydrogenation feed to maintain catalyst stability, reduce metal ion discharge, and enhance reaction selectivity and yield by adjusting the acid number in the feed between 10 and 90, thereby preventing acid-catalyzed side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cobalt-containing catalysts are used for hydrogenation of carboxylic acids and their derivatives, then the hydrogenation reaction can be carried out, but the catalyst is unstable in acidic conditions leading to reduced service life
Solution Approach 1:
Alkali metal or alkaline earth metal ions are introduced as intermediary substances that mediate between the acidic environment and the cobalt catalyst. These ions act as protective agents that prevent direct interaction between acids and the catalyst, thereby maintaining catalyst stability while allowing the hydrogenation reaction to proceed.
Solution Approach 2:
The invention changes the chemical environment parameters by adjusting the acid number in the feed to a specific range (10-90) and controlling the ratio of feed to circulation. This parameter optimization creates conditions where the catalyst remains stable despite the presence of acidic components in the reaction mixture.
2Productivity
If cobalt-containing catalysts are used for hydrogenation, then the desired diols can be produced, but side reactions such as dehydration and etherification occur reducing the yield
Solution Approach 1:
Alkali metal or alkaline earth metal ions serve as intermediary substances that inhibit the acid-catalyzed side reactions (dehydration and etherification) while allowing the main hydrogenation reaction to proceed. These ions act as protective agents that prevent the formation of harmful by-products.
Solution Approach 2:
The invention converts the harmful acidic environment into a beneficial condition by carefully controlling the acid number range (10-90) and using alkali/alkaline earth metal ions to neutralize excessive acidity. This transforms the previously harmful acidic conditions into optimized reaction conditions that favor the desired hydrogenation while suppressing side reactions.
3Reliability
If alkali metal salts of mineral acids are added to improve catalyst activity, then the service life may be extended, but the yield of desired end product decreases due to increased degradation of active catalyst metals
Solution Approach 1:
The invention specifies precise parameter ranges: the acid number in the feed is controlled to be between 10 and 90, and the ratio of feed to circulation is optimized. These parameter changes ensure that the catalyst remains stable and active while preventing excessive degradation that would reduce product yield.
Solution Approach 2:
The invention applies different properties to different components: cobalt catalyst for hydrogenation activity, alkali/alkaline earth metal ions for stability enhancement, and controlled acid number for reaction optimization. This local optimization of qualities ensures both high activity and long service life without compromising yield.
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 process extends the catalyst's service life, increases the yield of desired diols like 1,6-hexanediol, and reduces by-product formation, while maintaining catalyst activity and selectivity, even when the alkali metal ions are added in amounts insufficient to neutralize acids.
Implementation Method 1
hydrogenating a mixture containing carboxylic acid, carboxylic acid anhydrides and/or carboxylic acid esters/lactones using a cobalt-containing catalyst
Implementation Method 2
alkali metal and/or alkaline earth metal ions being added to the hydrogenation feed... the acid number in the feed before the catalyst, adjusted by the ratio of feed to circulation through the reactor or reactors, is between 10 and 90
Data Source
AI summary
The invention relates to a method for producing diols by hydrogenation of a mixture that contains carboxylic acid, carboxylic acid anhydrides and/or carbonic esters/lactones using a cobalt-containing catalyst, alkali ions and/or alkaline earth ions being added to the hydrogenation feed and alkali ions and/or alkaline earth ions of mineral acids being excluded.