Nickel-Copper Eggshell Catalyst Preparation for Selective Hydrogenation
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Solution Overview
Problem
Existing nickel-based catalysts for the selective hydrogenation of polyunsaturated compounds and aromatics suffer from inefficiencies in activity and selectivity due to homogeneous nickel distribution within the support, requiring higher nickel content and facing issues with intragranular mass transfer, which can lead to activity defects and loss of selectivity.
Innovation Solution
A process for preparing a catalyst with nickel and copper, where nickel is distributed both on the periphery and in the core of a porous alumina support, utilizing a butanol impregnation step followed by maturation, and optionally including a copper precursor to form a NiCu alloy, allowing for reduced nickel diffusion and improved accessibility, and enabling in-situ reduction at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nickel is distributed homogeneously within the support, then the catalyst can be manufactured with simple processes, but intragranular mass transfer problems occur leading to activity defects and loss of selectivity
Solution Approach 1:
The patent applies local quality by creating an eggshell catalyst where nickel is concentrated in a peripheral crust layer (2-15 μm thick) rather than being uniformly distributed. This localized concentration of active phase in the region where mass transfer is most efficient resolves the contradiction by maintaining high activity and selectivity while avoiding the manufacturing complexity of precise spatial control
2Reliability
If nickel content is increased to compensate for lower activity compared to palladium, then catalyst activity can be maintained, but the quantity of nickel required increases significantly
Solution Approach 1:
By concentrating nickel in a peripheral crust rather than distributing it uniformly, the patent achieves high local activity where it is most needed for mass transfer efficiency. This allows using lower overall nickel content (1-10 wt%) while maintaining catalyst performance, resolving the contradiction between activity and material quantity
3Reliability
If a peripheral crust structure is created to improve mass transfer, then activity and selectivity are enhanced, but the preparation process becomes more complex
Solution Approach 1:
The patent uses preliminary action by first depositing a thin layer of alumina or silica on the support surface to create a scaffold for subsequent nickel deposition. This pre-prepared surface structure guides the formation of the eggshell crust during standard impregnation procedures, achieving complex spatial distribution without complex processing
Solution Approach 2:
The patent introduces an intermediary material (alumina or silica layer) that mediates between the support and nickel active phase. This intermediary layer controls nickel deposition to form the peripheral crust structure, simplifying the overall process while achieving the desired eggshell morphology
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 results in a catalyst with enhanced activity and selectivity for hydrogenation reactions, using lower nickel quantities and maintaining catalyst performance with reduced nickel migration, while also allowing for in-situ reduction without additional passivation steps.
Implementation Method 1
a) the porous support is impregnated with a volume V1 of a butanol solution between 0.2 and 0.8 times the total porous volume VPT of said support
Implementation Method 2
which makes it possible to limit the diffusion of the active nickel phase during the maturation step
Implementation Method 3
step e) the catalyst precursor obtained at the end of the sequence of steps a) to d) is reduced by contacting said catalyst precursor with a reducing gas
Implementation Method 4
d1) either the porous support, or the matured impregnated porous support obtained at the end of step b), or the catalyst precursor obtained at the end of step c), is impregnated with at least one solution containing at least one copper precursor and one nickel precursor
Data Source
Figure 1
AI summary
Disclosed is a method for preparing a catalyst containing nickel and copper, the method comprising the following steps: - impregnating the porous carrier with a volume of a butanol solution of between 0.2 and 0.8 times the total pore volume of the carrier; - maturing the impregnated porous carrier for 0.5 to 40 hours; - impregnating the matured impregnated carrier with a solution comprising a precursor of the nickel active phase; - impregnating the carrier with a solution containing a copper precursor and a nickel precursor.