Mesoporous Nickel Catalyst for Hydrogenation Activity
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Solution Overview
Problem
Existing catalysts for hydrogenation reactions, particularly selective hydrogenation of polyunsaturated compounds and aromatic hydrocarbons, face challenges in optimizing the size and distribution of nickel particles and the porous structure of the support, which affects activity and mechanical strength.
Innovation Solution
A catalyst with a predominantly calcined aluminum oxide support and nickel as the active phase, featuring a specific porous distribution with a high mesoporous volume and low macroporous volume, optimized nickel content, and controlled nickel particle size, prepared through a precise alumina gel preparation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the nickel content is increased to improve hydrogenation activity, then the catalytic performance is enhanced, but the cost and complexity of catalyst preparation increase
Solution Approach 1:
The patent optimizes the nickel content within a specific range (5-65 wt%) rather than using excessive amounts, and controls the calcination temperature (500-1000°C) to achieve the desired particle size and phase composition. This parameter optimization approach improves hydrogenation activity while avoiding the need for complex preparation procedures.
2Productivity
If the nickel particle size is reduced to increase surface area and activity, then the catalytic performance is improved, but the particle size distribution control becomes more difficult
Solution Approach 1:
The patent achieves controlled nickel particle sizes (diameter ≤ 20 nm) by optimizing the calcination temperature (500-1000°C) and controlling the nickel content (5-65 wt%). These parameter changes enable the formation of small, uniformly distributed particles without requiring complex size control mechanisms during preparation.
Solution Approach 2:
The patent incorporates nickel precursors into the alumina gel structure before calcination, ensuring uniform distribution of nickel species throughout the support. This preliminary incorporation prevents agglomeration during heating and facilitates the formation of small, evenly distributed particles after calcination.
3Strength
If the macroporous volume is increased to improve mechanical strength, then the catalyst durability is enhanced, but the diffusion of reagents to active sites is hindered
Solution Approach 1:
The patent utilizes a predominantly calcined aluminum oxide support with optimized porosity characteristics, where the calcination process develops an appropriate pore structure that balances mechanical strength and mass transport. The support provides sufficient macroporosity for structural integrity while maintaining adequate mesopore networks for reagent diffusion.
Solution Approach 2:
The catalyst comprises a composite structure of nickel particles dispersed on a calcined alumina support, where the two materials complement each other: the alumina provides mechanical strength and thermal stability, while the nickel particles provide catalytic activity. The interface between these components creates an optimized structure for both strength and diffusion.
4Productivity
If the mesoporous volume is increased to enhance reagent diffusion, then the catalytic efficiency is improved, but the mechanical strength of the support is reduced
Solution Approach 1:
The patent optimizes the calcination temperature (500-1000°C) to transform the alumina gel into a predominantly calcined aluminum oxide support with balanced porosity. This parameter change develops a pore structure with adequate mesoporous volume for diffusion while maintaining the crystalline structure necessary for mechanical strength.
Solution Approach 2:
The nickel precursors are incorporated into the alumina gel matrix before calcination, creating a composite precursor structure where nickel species are uniformly distributed within the gel pores. This preliminary incorporation ensures that after calcination, the resulting catalyst maintains structural integrity while providing accessible active sites for efficient catalysis.
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 hydrogenation performance comparable to or better than state-of-the-art catalysts, with improved activity and mechanical strength, enabling efficient diffusion of reagents and products while maintaining catalyst stability.
Implementation Method 1
selective hydrogenation of polyunsaturated compounds or hydrogenation of aromatic
Implementation Method 2
the diffusion of the reactants on the surface of the catalyst (external diffusional limitations), the diffusion of the reactants in the porosity of the support towards the active sites
Data Source
AI summary
The invention relates to a supported catalyst comprising a predominantly calcined aluminium oxide support and an active phase comprising nickel, the nickel content being between 5 and 65% by weight of said element relative to the total mass of the catalyst, said active phase not comprising group VIB metals, the nickel particles having a diameter less than or equal to 20 nm, said catalyst having a mesoporous median diameter greater than or equal to 14 nm, a mesoporous volume measured by mercury porosimetry of greater than or equal to 0.45 ml/g, a total porous volume measured by mercury porosimetry greater than or equal to 0.45 ml/g, a macroporous volume less than 5% of the total porous volume, said catalyst being in the form of grains having a mean diameter of between 0.5 et 0 mm. The invention also relates to the method for preparation of said catalyst and the use of same in a hydrogenation method.