Adiponitrile Hydrogenation with Basic Co-Catalysts for Cleaner HMDA
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Solution Overview
Problem
Existing hydrogenation processes using Raney nickel catalysts for producing hexamethylenediamine from adiponitrile suffer from high diaminocyclohexane formation, making separation difficult and increasing capital and energy costs.
Innovation Solution
A process utilizing a Raney nickel catalyst in combination with a basic co-catalyst containing potassium hydroxide and additional basic compounds like cesium hydroxide or barium hydroxide to minimize diaminocyclohexane formation, using hexamethylenediamine as solvent, and operating under controlled temperature and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Raney nickel catalyst is used for hydrogenation of adiponitrile, then hydrogenation activity is improved, but diaminocyclohexane formation increases
Solution Approach 1:
The invention changes the chemical composition parameters of the catalyst system by introducing a basic co-catalyst (alkali metal hydroxide, alkaline earth metal hydroxide, or ammonium hydroxide) in combination with Raney nickel. This parameter change modifies the catalytic properties to reduce diaminocyclohexane formation while maintaining hydrogenation activity. The basic co-catalyst concentration is optimized at 0.1-10 wt% relative to the catalyst weight.
Solution Approach 2:
The invention creates a composite catalyst system combining Raney nickel with a basic co-catalyst. This composite approach leverages the hydrogenation activity of Raney nickel while the basic co-catalyst component suppresses the formation of diaminocyclohexane side product, achieving synergistic effects that resolve the technical contradiction.
2Ease of manufacture
If diaminocyclohexane formation is reduced, then purification cost decreases, but catalyst selectivity must be improved
Solution Approach 1:
The invention optimizes the selectivity parameter of the catalyst by adjusting the composition and concentration of the basic co-catalyst. By precisely controlling the amount of basic co-catalyst (0.1-10 wt%) and its specific composition, the catalyst achieves high selectivity for hexamethylenediamine production, which directly reduces purification costs and complexity.
3Object-generated harmful factors
If basic co-catalyst concentration is increased, then diaminocyclohexane formation decreases, but catalyst deactivation increases
Solution Approach 1:
The invention identifies and optimizes the concentration parameter of the basic co-catalyst to achieve a balance between reducing diaminocyclohexane formation and preventing catalyst deactivation. The optimal concentration range of 0.1-10 wt% was determined through systematic parameter optimization, where concentrations below this range are insufficient to suppress side reactions, while concentrations above this range cause excessive catalyst deactivation.
Solution Approach 2:
The invention applies partial action by using a moderate concentration of basic co-catalyst (0.1-10 wt%) that is sufficient to suppress diaminocyclohexane formation but not excessive enough to cause severe catalyst deactivation. This optimized partial concentration achieves the desired effect without the harmful consequences of excessive base addition.
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
Reduces diaminocyclohexane formation, improving catalyst selectivity and activity, thereby facilitating easier purification and reducing energy consumption.
Implementation Method 1
hydrogenation of adiponitrile in the presence of a Raney nickel catalyst
Implementation Method 2
basic co-catalyst containing potassium hydroxide, wherein the basic co-catalyst contains a further basic compound selected from the group consisting of alkaline hydroxides, alkaline earth hydroxides and ammonium hydroxides
Data Source
AI summary
The present invention relates to a process for the preparation of hexamethylenediamine by hydrogenation of adiponitrile in the presence of a Raney nickel catalyst and a basic co-catalyst containing potassium hydroxide, wherein the basic co-catalyst contains a further basic compound selected from the group consisting of alkaline hydroxides, alkaline earth hydroxides and ammonium hydroxides.