Copper Impregnation Catalyst for Selective Nitroaromatic Hydrogenation
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Solution Overview
Problem
Existing catalysts for the hydrogenation of nitroaromatics, particularly nitrobenzene to aniline, face challenges in selectivity and long-term stability, especially those based on copper, which are less expensive than palladium but require improvements.
Innovation Solution
A process using a tetraamminecopper-based impregnated catalyst on shaped silicon dioxide or silicon carbide bodies, prepared by the incipient wetness method, with a molar proportion of Cu ranging from 0.75 to 1, and activated under specific conditions, is employed for hydrogenation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper-based catalysts are used for hydrogenation of nitroaromatics, then cost is reduced compared to palladium catalysts, but selectivity and long-term stability deteriorate
Solution Approach 1:
The patent uses a composite catalyst system combining copper (0.75-1.0 mol proportion) with zinc (0.0-0.25 mol proportion) on a supported carrier. This composite approach allows copper to provide cost benefits while zinc enhances selectivity and stability, resolving the contradiction between low cost and high performance.
Solution Approach 2:
The patent optimizes specific parameters including copper content (0.75-1.0 mol proportion), zinc content (0.0-0.25 mol proportion), carrier type (silicon dioxide or silicon carbide), and preparation method (incipient wetness impregnation). These parameter optimizations enable copper-based catalysts to achieve selectivity and stability comparable to palladium while maintaining cost advantages.
2Productivity
If traditional copper catalysts are used, then cost is lower than palladium catalysts, but catalyst performance and selectivity worsen
Solution Approach 1:
The patent applies local quality by creating specific active sites on the catalyst surface through controlled impregnation of copper and zinc salts onto the carrier. The incipient wetness method ensures optimal distribution of metal species, creating localized high-performance regions that enhance overall catalyst performance while maintaining cost-effectiveness.
Solution Approach 2:
The patent changes key parameters including metal composition (Cu 0.75-1.0, Zn 0.0-0.25), carrier material (SiO2 or SiC), and preparation conditions (incipient wetness impregnation). These parameter changes transform traditional copper catalysts into high-performance catalysts that match or exceed palladium performance at lower cost.
3Ease of manufacture
If copper catalysts are used instead of palladium, then manufacturing cost decreases, but reaction selectivity and stability deteriorate
Solution Approach 1:
The patent introduces zinc as an intermediary element that mediates between copper and the reaction system. Zinc modifies the electronic and geometric properties of copper active sites, enhancing selectivity and stability while maintaining the cost advantages of copper-based catalysts.
Solution Approach 2:
The composite Cu-Zn catalyst system on supported carrier combines the cost benefits of copper with the performance-enhancing properties of zinc. This composite material approach resolves the contradiction by achieving both low manufacturing cost and high reaction selectivity/stability simultaneously.
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 enhances the selectivity and stability of the hydrogenation reaction, improving the production of aromatic amines like aniline with improved catalyst performance.
Implementation Method 1
reacting the aromatic nitro compound with hydrogen in the presence of the optionally activated hydrogenation catalyst to obtain the aromatic amine
Implementation Method 2
providing a tetraaminecopper-based impregnated catalyst, especially an impregnated catalyst obtainable by the incipient wetness method, comprising a metal or metal oxide on a support
Data Source
AI summary
The present invention relates to a process for the preparation of an aromatic amine by hydrogenation of an aromatic nitro compound, comprising the following steps: (I) providing a copper tetramine salt-based impregnation catalyst, in particular an impregnation catalyst obtainable by the incipient wetness method, comprising a metal or metal oxide on a support as a hydrogenation catalyst. At least metallic or oxidic copper (in particular CuO) is present and the mole fraction of Cu based on all metals present is in the range of 075 to 1, and wherein the support comprises shaped silicon-dioxide shaped bodies or silicon-carbide shaped bodies; (II) optionally, activating the hydrogenation catalyst by treating with hydrogen in the absence of the aromatic nitro compound; and (III) reacting the aromatic nitro compound with hydrogen in the presence of the, optionally activated, hydrogenation catalyst to obtain the aromatic amine.