Selective Hydrogenation Catalyst Shell Structure
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Solution Overview
Problem
Current catalysts for selective hydrogenation of unsaturated compounds in hydrocarbon streams suffer from low olefin selectivity, high green oil formation, and short catalyst lifetime, particularly in C4 hydrogenation, where 1-butene selectivity is compromised by double bond isomerization.
Innovation Solution
A catalyst comprising at least 80% of a Group VIII metal, such as palladium, in a homogeneous distribution within a surface layer and penetration depth of up to 80% of the catalyst radius, combined with a promoter like silver, supported on alumina, forming a shell structure to enhance selectivity and reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hydrogenation catalysts are used to remove unsaturated compounds, then hydrogenation activity is achieved, but olefin selectivity is low and green oil formation is high
Solution Approach 1:
The patent applies local quality by creating a shell structure where Group VIII metals are concentrated in a surface layer (penetration depth up to 80% of catalyst radius) rather than uniformly distributed throughout the catalyst. This localized metal distribution in the shell provides high hydrogenation activity and selectivity at the catalyst surface where reactions occur, while the core support material provides structural stability and prevents green oil formation throughout the catalyst volume.
Solution Approach 2:
The patent uses composite materials by combining Group VIII metals (such as palladium) with alumina support material in a shell structure. The composite catalyst comprises a metal shell layer containing the hydrogenation-active Group VIII metals and a core support material (alumina), creating a composite structure that synergistically provides both high olefin selectivity and reduced green oil formation.
2Productivity
If conventional catalysts are used for C4 hydrogenation, then butadiene conversion is achieved, but 1-butene selectivity is compromised by double bond isomerization
Solution Approach 1:
The shell structure concentrates Group VIII metals in the surface layer, creating a localized reaction zone with controlled hydrogenation activity. This local metal distribution enables high butadiene conversion at the shell surface while minimizing isomerization reactions that would occur with uniform metal distribution throughout the catalyst, thereby maintaining high 1-butene selectivity.
3Ease of manufacture
If uniform metal distribution is used in catalysts, then manufacturing simplicity is maintained, but hydrogenation activity and selectivity are reduced
Solution Approach 1:
The patent changes the distribution parameter of metal in the catalyst from uniform to non-uniform (shell structure). By controlling the metal penetration depth to be up to 80% of the catalyst radius, the patent creates a shell structure that can be manufactured through controlled impregnation and drying processes, achieving both reasonable manufacturing simplicity and superior hydrogenation activity through the concentrated metal shell.
4Productivity
If high metal content is used throughout the catalyst, then hydrogenation activity is maximized, but green oil formation increases and catalyst lifetime decreases
Solution Approach 1:
The shell structure localizes high metal content to the surface layer where hydrogenation reactions occur, maximizing hydrogenation activity at the catalyst surface. The core support material remains metal-free, preventing green oil formation and catalyst deactivation throughout the catalyst volume, thereby extending catalyst lifetime while maintaining high activity.
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 high hydrogenation activity, selective conversion of 1,3-butadiene to 1-butene with reduced green oil formation and minimized double bond isomerization, leading to improved catalyst longevity and product quality.
Implementation Method 1
selective hydrogenation of unsaturated compounds in hydrocarbon streams
Implementation Method 2
catalyst comprises at least 80% of a metal of group VIII of the Periodic Table of the Elements as a hydrogenating metal
Data Source
AI summary
A catalyst on an oxidic support and processes for selectively hydrogenating unsaturated compounds in hydrocarbon streams comprising them using these catalysts are described.