Nickel-Copper Shell Catalyst Preparation for Selective Hydrogenation
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Solution Overview
Problem
Existing nickel-based catalysts for selective hydrogenation of polyunsaturated compounds and aromatics require high nickel content due to nickel's lower activity compared to palladium, and achieving optimal activity and selectivity is hindered by uniform distribution within the support, leading to inefficiencies.
Innovation Solution
A process for preparing a catalyst with a specific distribution of nickel and copper on both the periphery and core of a porous alumina support, utilizing a butanol impregnation step followed by maturation, which limits nickel migration to the core and forms a nickel-copper alloy, allowing for reduced nickel usage and improved accessibility to reagents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel is used as the active metal phase instead of palladium, then the catalyst cost is reduced, but the nickel content must be increased to compensate for lower activity
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of nickel within the support grain. A crust layer with higher nickel concentration (5-15 wt% relative to catalyst) is formed at the periphery (within 10-20 μm from the surface), while the core contains lower nickel concentration. This spatial variation in composition allows the catalyst to achieve high activity with lower overall nickel content (5-20 wt% relative to support), resolving the contradiction between using cheaper nickel and maintaining catalyst productivity.
2Productivity
If nickel is uniformly distributed within the support, then the preparation process is simple, but the catalyst shows reduced activity and selectivity
Solution Approach 1:
The patent employs preliminary action by pre-forming a crust layer on the support surface before introducing the nickel precursor. The support is first treated to create a porous outer layer with different properties than the core, then the nickel precursor is impregnated. This preliminary structuring of the support enables subsequent controlled nickel deposition in the crust region, achieving the desired non-uniform distribution without requiring complex in-situ control mechanisms during the impregnation process itself.
Solution Approach 2:
The patent uses an intermediary approach by introducing a binding agent (such as silica alumina or titania) that mediates between the support and nickel precursor. This binding agent layer facilitates selective nickel deposition in the crust region by controlling precursor access and distribution, enabling the formation of the desired concentration gradient without direct complex control of nickel placement.
3Productivity
If high nickel content is used to compensate for lower activity, then sufficient catalytic activity is achieved, but the selectivity for partial hydrogenation decreases
Solution Approach 1:
The patent resolves the activity-selectivity contradiction by applying local quality through spatially differentiated nickel distribution. The crust layer with higher nickel concentration (5-15 wt% relative to catalyst) provides sufficient catalytic activity for hydrogenation, while the lower overall nickel content (5-20 wt% relative to support) and reduced core concentration prevent excessive activity that would lead to over-hydrogenation. This local concentration gradient enables the catalyst to maintain both high activity and good selectivity for partial hydrogenation products.
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 catalyst achieves high activity and selectivity in hydrogenation reactions with lower nickel content, enabling efficient conversion of polyunsaturated compounds and aromatics while reducing the need for additional reduction steps and passivation.
Implementation Method 1
utilizing a butanol impregnation step followed by maturation, which limits nickel migration to the core
Implementation Method 2
said sequence comprising: a) the porous support is impregnated with a volume V1 of a butanol solution
Implementation Method 3
intended particularly for the hydrogenation of unsaturated hydrocarbons, and more particularly for the selective hydrogenation of polyunsaturated compounds or the hydrogenation of aromatics
Data Source
AI summary
A process for preparing a catalyst comprising nickel and copper, comprising the following steps:impregnating the porous support with a volume of a butanol solution of between 0.2 and 0.8 times the total pore volume of the support;maturing the impregnated porous support for 0.5 to 40 hours;impregnating the matured impregnated support with a solution comprising a precursor of the nickel active phase;impregnating the support with a solution containing a copper precursor and a nickel precursor.