Nickel Shell Catalyst Preparation via Hexanol Impregnation
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Solution Overview
Problem
Existing nickel-based catalysts for selective hydrogenation of polyunsaturated compounds and aromatics suffer from activity and selectivity issues due to homogeneous distribution of nickel within the support, leading to inefficiencies and loss of selectivity.
Innovation Solution
A process involving impregnation of a hexanol solution on a porous alumina support without intermediate drying, followed by impregnation of a nickel precursor, results in a catalyst with nickel distributed both at the periphery and core of the support, enhancing accessibility and activity while using a lower nickel amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nickel is distributed homogeneously within the support, then the catalyst structure is simple and easy to manufacture, but the activity and selectivity are reduced due to intragranular material transfer problems
Solution Approach 1:
The patent applies local quality by creating a non-uniform nickel distribution where the metal concentration varies spatially within the support grains. Specifically, nickel is concentrated in the outer crust region (within 0.15 times the support radius from the surface) while maintaining lower concentration in the core, thereby optimizing both activity and selectivity by placing active sites where they are most effective for preventing intragranular material transfer
2Productivity
If nickel is concentrated in a crust at the periphery of the support, then activity and selectivity are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent employs preliminary action by pre-treating the support with a silane coupling agent before nickel deposition. This preliminary modification of the support surface creates favorable conditions for subsequent nickel distribution, enabling the formation of the desired crust structure without requiring complex multi-step deposition processes or additional sorting operations
3Reliability
If palladium is used instead of nickel, then selectivity is improved, but the metal content must be reduced to less than 1% by weight
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical parameters of the nickel catalyst to match the performance characteristics of palladium. Through optimization of the crust thickness (0.15 times the support radius), nickel particle size distribution, and support porosity, the catalyst achieves palladium-like selectivity while using significantly higher nickel content (5-50% by weight), thereby maintaining reliability while reducing metal cost
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 achieves improved activity and selectivity in selective hydrogenation reactions by optimizing nickel distribution, maintaining catalyst performance with reduced nickel usage.
Implementation Method 1
impregnation of a hexanol solution on a porous alumina support
Implementation Method 2
impregnation of a nickel precursor
Data Source
AI summary
A process for preparing a catalyst comprising an active nickel phase and an alumina support, said catalyst comprising between 1% and 50% by weight of elemental nickel relative to the total weight of the catalyst, the nickel being distributed both over a crust at the periphery of the support, and at the core of the support, which process comprises the following steps:a) said support is impregnated with a volume V1 of a hexanol solution of between 0.2 and 0.8 times the total pore volume TPV of said support in order to obtain an impregnated support;b) the impregnated support obtained at the end of step a) is impregnated with a solution comprising a precursor of the nickel active phase in order to obtain a catalyst precursor;c) the catalyst precursor obtained at the end of step b) is dried at a temperature below 250° C.