Pd-Ru Hydrorefining Catalyst for Stable 4-CBA Conversion
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Solution Overview
Problem
Existing hydrorefining catalysts for crude terephthalic acid suffer from low conversion of 4-CBA and poor thermal stability due to palladium grain growth, leading to rapid deactivation and economic losses.
Innovation Solution
A catalyst comprising palladium and ruthenium as active components, with a controlled weight ratio of Ru4+ and Ru0, is prepared using a method involving mixing with alkylamine, aging, and reducing agents to achieve a core-shell structure, enhancing catalytic activity and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If palladium/carbon catalysts are used for hydrorefining crude terephthalic acid, then catalytic activity is achieved, but palladium grain growth occurs leading to catalyst deactivation
Solution Approach 1:
The patent uses a core-shell structure combining carbon support with metal oxide shell (such as tungsten oxide, molybdenum oxide, or their mixed oxides) to create a composite catalyst. This composite structure prevents palladium grain growth while maintaining catalytic activity, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent employs a thin metal oxide shell or coating on the carbon support surface to prevent palladium grain growth. This shell acts as a physical barrier that constrains palladium particles, maintaining their small size and catalytic activity over time, thus improving catalyst stability without sacrificing activity.
2Productivity
If active component is dispersed throughout the support, then maximum utilization of active component is achieved, but mass transfer limitations occur
Solution Approach 1:
The patent creates a non-uniform distribution of palladium within the core-shell structure, concentrating active palladium species at the interface between the carbon core and metal oxide shell. This local concentration optimizes both mass transfer access and active component utilization, resolving the contradiction between speed and productivity.
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 4-CBA conversion rates of at least 85% and inhibits palladium grain growth, ensuring efficient and stable hydrorefining of crude terephthalic acid.
Implementation Method 1
The hydrorefining of crude terephthalic acid may usually use palladium/carbon catalysts. the active components comprise palladium and ruthenium
Implementation Method 2
converting it into other compounds (such as p-Toluic acid) through hydrogenation
Implementation Method 3
mixing with alkylamine, aging, and reducing agents to achieve a core-shell structure
Data Source
AI summary
A catalyst for hydrorefining crude terephthalic acid, as well as its preparation method and application are provided. The catalyst includes a support and active components. The active components contains palladium and ruthenium in a weight ratio of (3-10):1, on element basis. The palladium is Pd0, and ruthenium includes Ru0 and Ru4+. Ru4+ and Ru0 are in a weight ratio of 0.1-1.0. The catalyst may be particularly suitable for hydrorefining crude terephthalic acid.