Platinum Catalyst Selectivity in Halonitroaromatic Hydrogenation
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Solution Overview
Problem
Current processes for catalytic hydrogenation of halonitroaromatics face challenges in maintaining selectivity due to dehalogenation, often requiring additional catalyst modifiers that increase costs and introduce metal contaminants, necessitating further separation steps.
Innovation Solution
The process involves using a platinum-containing catalyst on a carbon support, specifically a calcined hydrogenation catalyst without dehalogenation suppressors, with controlled platinum particle size distribution to minimize dehalogenation and reduce the need for extraneous additives, thereby enhancing selectivity and process economics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If catalyst modifiers or additives are introduced to suppress dehalogenation, then selectivity to haloaminoaromatic product is improved, but process complexity and cost increase
Solution Approach 1:
The patent removes catalyst modifiers and additives from the hydrogenation system, using only a simple platinum on carbon catalyst without any suppressors or promoters, thereby simplifying the process while maintaining high selectivity through optimized catalyst preparation
Solution Approach 2:
The patent changes the catalyst preparation parameters, specifically using a simple impregnation method with platinum nitrate followed by drying and calcination at 400-600°C, which produces optimal catalyst activity and selectivity without requiring additional modifiers
2Manufacturing precision
If catalyst modifiers are introduced to suppress dehalogenation, then selectivity to haloaminoaromatic product is improved, but process cost increases
Solution Approach 1:
The patent eliminates expensive catalyst modifiers and additives from the system, achieving cost reduction by using only platinum metal on carbon support with standard preparation procedures
Solution Approach 2:
The patent uses a simple, inexpensive catalyst preparation method involving common chemicals like platinum nitrate and nitric acid, avoiding costly specialized modifiers while achieving comparable or superior performance
3Manufacturing precision
If catalyst modifiers are introduced to suppress dehalogenation, then selectivity to haloaminoaromatic product is improved, but separation operations increase
Solution Approach 1:
The patent removes all catalyst modifiers and additives from the reaction system, eliminating the source of metal contaminants and undesired reaction products that would require additional separation steps
Solution Approach 2:
The simple platinum on carbon catalyst performs both hydrogenation and suppresses dehalogenation without requiring auxiliary modifiers, and the reaction mixture remains clean without contaminants that would need separation
4Loss of substance
If dehalogenation suppressors are used, then dehalogenation loss is reduced, but metal contaminants are introduced
Solution Approach 1:
The patent uses the inherent properties of platinum metal on carbon support to achieve both high hydrogenation activity and suppression of dehalogenation, converting what would be a harmful side reaction into a beneficial selectivity enhancement without introducing contaminants
Solution Approach 2:
The patent uses a simple platinum on carbon catalyst without any additional suppressor chemicals, avoiding the introduction of metal contaminants while still achieving effective dehalogenation suppression through catalyst design
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 achieves high selectivity for haloaminoaromatic products with reduced dehalogenation loss, minimizing the use of additional components and subsequent separation processes, leading to improved process economics and stability of the catalyst under various conditions.
Implementation Method 1
The catalytic hydrogenation of halonitroaromatics is a reaction of significant industrial importance because the resulting haloaminoaromatic compounds (e.g., haloanilines) are useful as intermediates
Implementation Method 2
processes for the catalytic hydrogenation of halonitroaromatics such as 2,5-dicloronitrobenzene to 2,5-dichloroaniline
Data Source
AI summary
The present invention generally relates to processes for the catalytic hydrogenation of halonitroaromatics. In particular, the present invention includes processes for the catalytic hydrogenation of halonitroaromatics such as 2,5-dicloronitrobenzene to 2,5-dichloroaniline over a platinum-containing catalyst. The present invention also relates to processes for producing 3,6-dichloro-2-methoxybenzoic acid.