Selective Hydrogenation Catalyst with Peripheral Palladium Crust
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Solution Overview
Problem
Current selective hydrogenation catalysts for unsaturated hydrocarbon compounds, particularly those from steam cracking or catalytic cracking, face challenges in achieving optimal catalytic activity and selectivity due to limitations in palladium distribution and catalyst shape, leading to inefficient conversion of polyunsaturated compounds into alkenes without complete saturation.
Innovation Solution
A catalyst comprising palladium supported on a refractory oxide extrudate with a specific surface area of 165 to 250 m2/g, where at least 80% of the palladium is distributed in a crust at the periphery of the support, and optionally including silver, is used to enhance catalytic activity and selectivity, with a process involving preparation steps such as impregnation, maturation, drying, and calcination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalysts are shaped using conventional methods (beads, cylinders, wheels), then the structural and textural properties can be maintained, but the dispersion of metallic particles on the catalyst support is not optimized and catalytic activity is reduced
Solution Approach 1:
The patent applies parameter changes by modifying the specific surface area of the extrudate support to a specific range (165-250 m²/g) and changing the shape from conventional forms to extrudates with specific geometric characteristics. This optimization of physical parameters enables improved metallic particle dispersion and enhanced catalytic activity while maintaining structural integrity.
2Reliability
If palladium particles are located in a crust at the periphery of the support, then intragranular material transfer problems are avoided, but the distribution and accessibility of active phase may be limited
Solution Approach 1:
The patent applies local quality by creating a crust structure where 80-95% of palladium is concentrated at the periphery within a specific thickness range (20-100 μm). This localized distribution optimizes both selectivity by preventing intragranular transfer issues and catalytic activity through improved surface accessibility and dispersion on the extrudate geometry.
3Productivity
If the specific surface area of the support is increased, then the dispersion of metallic particles is improved and catalytic activity increases, but the complexity of catalyst preparation may increase
Solution Approach 1:
The patent resolves this contradiction by specifying an optimal range for specific surface area (165-250 m²/g) that balances enhanced metallic particle dispersion and catalytic activity with feasible preparation methods. This parameter optimization ensures high performance while maintaining practical manufacturability through standard extrusion and impregnation techniques.
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 exhibits significantly higher catalytic activity and improved selectivity, enabling more effective conversion of polyunsaturated hydrocarbons into alkenes while avoiding complete saturation, as demonstrated by increased hydrogenation rates and reduced formation of alkanes.
Implementation Method 1
Catalysts for the selective hydrogenation of such cuts are often based on palladium
Implementation Method 2
selective hydrogenation process can be used to transform the polyunsaturated compounds of oil cuts by conversion of the most unsaturated compounds into the corresponding alkenes
Implementation Method 3
palladium in the form of small metallic particles deposited on a support
Implementation Method 4
a porous support comprising at least one refractory oxide selected from the group constituted by silica, alumina and silica-alumina
Data Source
AI summary
A catalyst comprising palladium, a porous support comprising at least one refractory oxide selected from the group constituted by silica, alumina and silica-alumina, the palladium content in the catalyst being in the range 0.01% to 2% by weight with respect to the total catalyst weight, at least 80% by weight of the palladium being distributed in a crust at the periphery of said support, the thickness of said crust being in the range 20 to 100 μm, characterized in that said support is in the form of an extrudate and in that said support comprises a specific surface area in the range 165 to 250 m2/g.