Gold-Palladium Catalyst for CO-Resistant Selective Hydrogenation
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Solution Overview
Problem
Existing selective hydrogenation catalysts based on palladium are sensitive to changes in carbon monoxide concentrations, affecting their activity and stability, particularly in front-end configurations where a large excess of hydrogen and varying carbon monoxide levels are present.
Innovation Solution
A catalyst comprising gold and palladium with gold dispersed homogeneously in a porous support and palladium distributed in an eggshell configuration at the periphery, with a high gold/palladium molar ratio, is developed. The catalyst preparation process involves distinct steps for palladium and gold deposition, including calcining and a reduction treatment, to ensure stability and activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If palladium-based catalysts are used for selective hydrogenation in front-end configurations, then hydrogenation activity is achieved, but the catalyst activity and stability are sensitive to changes in carbon monoxide concentrations
Solution Approach 1:
The patent uses a composite catalyst system combining gold and palladium metals on a support. The gold component (0.01-0.1 wt%) acts as a stabilizing agent that buffers against CO concentration fluctuations, while the palladium component (0.001-0.028 wt%) provides the hydrogenation activity. This composite structure resolves the contradiction by integrating two materials with complementary functions.
Solution Approach 2:
The patent distributes the metals in specific spatial configurations: gold is dispersed throughout the catalyst volume while palladium is concentrated in an eggshell pattern at the periphery. This local differentiation allows gold to provide bulk stabilization against CO effects while palladium at the surface maintains high activity for hydrogenation reactions.
2Reliability
If gold content is increased to improve catalyst stability, then stability towards CO concentration changes is enhanced, but catalyst cost increases
Solution Approach 1:
The patent applies partial action by using a small, optimized amount of gold (0.01-0.1 wt%) rather than large quantities. This minimal gold content is sufficient to provide the buffering effect against CO concentration changes while avoiding excessive cost. The range is carefully defined to achieve stability with the smallest necessary gold quantity.
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 improved stability and activity by maintaining performance across varying CO concentrations, acting as a buffer to prevent sudden changes in CO levels, thereby enhancing the selective hydrogenation of C2-C4 cuts in front-end configurations.
Implementation Method 1
The catalyst preparation process involves distinct steps for palladium and gold deposition, including calcining
Implementation Method 2
A catalyst comprising gold and palladium with gold dispersed homogeneously in a porous support and palladium distributed in an eggshell configuration at the periphery, with a high gold/palladium molar ratio, is developed
Implementation Method 3
the stability of the catalyst in accordance with the invention is favoured by the presence of a large number of metallic gold sites, obtained for catalysts containing a large quantity by weight of gold; the gold is dispersed on a nanometric scale within the support
Data Source
AI summary
A catalyst comprising gold, palladium, and a porous support, in the form of at least one grain, in which:the gold content in the catalyst is in the range 0.5% to 3% by weight with respect to the total weight of catalyst;the mean particle size of the gold, estimated by transmission electron microscopy (TEM), is in the range 0.5 nm to 5 nm;the gold is distributed homogeneously in the porous support;at least 80% by weight of the palladium is distributed in an eggshell at the periphery of the porous support;the gold/palladium molar ratio is more than 2.