Pre-gold-plated Pd-Au-Co Shell Catalysts for Vinyl Acetate
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Solution Overview
Problem
Current catalysts for producing vinyl acetate monomer (VAM) face challenges in achieving optimal activity and selectivity, particularly due to high capital intensity and rising raw material costs, necessitating an improvement in catalyst economics and performance.
Innovation Solution
A process involving a circulation movement of a catalyst support body, followed by atomized aqueous solutions of Au and Pd precursor compounds, with subsequent reduction in a non-oxidizing atmosphere, results in a shell catalyst with enhanced selectivity and activity, characterized by specific weight proportions of Au and Pd, and a controlled shell thickness for uniform metal distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional impregnation methods are used to apply metal precursor compounds to catalyst support, then the catalyst can be produced with standard manufacturing simplicity, but the selectivity and activity of the catalyst are insufficient
Solution Approach 1:
The patent applies sequential impregnation in multiple steps, first applying Au-containing precursor compound, drying, then applying Pd-containing precursor compound. This segmented approach allows independent optimization of each metal's distribution and concentration, achieving superior catalyst selectivity and activity compared to single-step conventional impregnation.
Solution Approach 2:
The patent performs preliminary drying of the catalyst support after Au impregnation before Pd impregnation. This preliminary action ensures proper solvent evaporation and metal precursor fixation, preventing aggregation and ensuring uniform distribution, which directly enhances catalyst selectivity and activity.
2Productivity
If high concentrations of precious metals are used to improve catalyst activity, then catalyst performance increases, but production costs increase due to capital intensity and raw material prices
Solution Approach 1:
The patent creates a core-shell structure where Au and Pd are concentrated in the outer shell region of the catalyst support particles. This local quality approach ensures high catalytic activity at the reaction interface while minimizing precious metal consumption in the bulk material, directly addressing the cost-performance trade-off.
Solution Approach 2:
The patent optimizes the concentration ratios and impregnation conditions to achieve a specific Au:Pd composition in the shell region. By carefully controlling parameters such as precursor concentration, impregnation time, and drying temperature, the patent achieves maximum catalyst activity with minimized precious metal loading.
3Manufacturing precision
If uniform metal distribution is achieved through prolonged impregnation, then catalyst performance improves, but production time and energy consumption increase
Solution Approach 1:
The patent divides the impregnation process into two separate sequential steps with drying in between. This segmentation allows each impregnation step to be optimized for shorter duration while achieving uniform distribution of individual metals, reducing total production time compared to prolonged single-step impregnation.
Solution Approach 2:
The patent uses the drying step as an intermediary between Au and Pd impregnation. This intermediary action removes solvent and fixes the Au precursor, creating optimal surface conditions for subsequent Pd impregnation. This accelerates the overall process while ensuring uniform metal distribution.
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 process produces shell catalysts with significantly increased selectivity and activity for VAM synthesis, optimizing catalyst performance and reducing production costs by ensuring efficient metal distribution and catalyst durability.
Implementation Method 1
subjecting a bed of a catalyst support body (support body) to a circulation movement
Implementation Method 2
bringing an atomized, aqueous solution containing an Au-containing precursor compound into contact with the bed of the catalyst support body subjected to the circulation movement by spraying
Implementation Method 3
reducing the metal components of the precursor compounds to the elemental metals by subjecting the catalyst support body obtained in step (c) to a temperature treatment in a non-oxidizing atmosphere
Data Source
Figure 1
AI summary
The invention relates to a method for producing a shell catalyst which is suitable for producing vinyl acetate monomer (VAM). The invention additionally relates to a shell catalyst which can be obtained using the method according to the invention and to the use of the shell catalyst according to the invention in order to produce VAM.