Shell-Type Catalyst Preparation for Vinyl Acetate Selectivity
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Solution Overview
Problem
Existing catalysts for alkenyl acetate production, such as those using Pd/Au/KOAc/SiO2, face challenges in achieving high vinyl acetate selectivity and preventing carbon dioxide gas generation, while also having complex preparation procedures and irregular metal loading, which affects their longevity and environmental impact.
Innovation Solution
A catalyst preparation process involving impregnation of a carrier with an alkali solution, followed by contact with a solution containing palladium or platinum and a Group 11 element, and subsequent reduction treatment, allowing for close adjacent loading of palladium and gold in a shell-type fashion, improving catalyst activity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the carrier is impregnated with alkali solution first and then contacted with starting metal salts solution, then shell-type catalyst is formed, but the preparation procedure becomes complex and metal loading becomes irregular
Solution Approach 1:
The patent inverts the conventional impregnation sequence by contacting the carrier with starting metal salts solution first, then adding alkali solution. This reversal simplifies the preparation procedure while achieving uniform metal loading and proper shell-type catalyst formation, directly resolving the contradiction between manufacturing precision and device complexity
Solution Approach 2:
The patent utilizes the water absorption capacity of the carrier itself to control the impregnation process. By matching the total amount of solutions to the carrier's water absorption, the system self-regulates the metal loading uniformity without requiring complex external control mechanisms, thereby simplifying the preparation procedure while maintaining manufacturing precision
2Duration of action of stationary object
If gold is added to inhibit sintering of palladium, then catalyst life is extended, but the preparation method becomes more complex and gold loading ratio is insufficient
Solution Approach 1:
The patent combines palladium and gold loading into a single impregnation step by dissolving both metal salts in the same starting metal salts solution. This merging approach ensures proper gold loading ratio for sintering inhibition while simplifying the preparation procedure, resolving the contradiction between extending catalyst life and reducing preparation complexity
Solution Approach 2:
The patent optimizes the concentration parameters of the starting metal salts solution to achieve the appropriate gold loading ratio. By carefully controlling the solution composition and total amount, the method ensures sufficient gold content for preventing palladium sintering without requiring complex multi-step preparation procedures
3Productivity
If vinyl acetate selectivity is increased, then productivity is improved, but carbon dioxide generation increases causing environmental load
Solution Approach 1:
The patent optimizes reaction parameters including temperature, pressure, and gas composition ratios to achieve high vinyl acetate selectivity while minimizing carbon dioxide generation. By carefully controlling these parameters, the system improves productivity without excessively increasing harmful emissions
Solution Approach 2:
The patent creates a shell-type catalyst structure where active components are concentrated at specific locations (shell region). This local concentration of catalytic activity enhances vinyl acetate selectivity while the controlled structure helps manage byproduct formation, addressing the contradiction between productivity and environmental impact
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 results in a catalyst with enhanced initial activity and selectivity, reducing carbon dioxide generation and extending catalyst life, thus addressing the limitations of existing methods.
Implementation Method 1
the carrier is impregnated with an alkali solution having a mass of greater than 0.9 times and no greater than 1.0 times the amount of water absorption of the carrier
Implementation Method 2
a step of reduction treatment
Data Source
AI summary
A catalyst is produced by a process that comprises at least a step of impregnating a carrier with an alkali solution having a mass of greater than 0.9 times and no greater than 1.0 times the amount of water absorption of the carrier, a step of further impregnating the carrier by contact with a solution A comprising at least a compound containing palladium or platinum and a compound containing a Group 11 element, a step of reduction treatment and a step of loading an acetic acid salt on the carrier, wherein the carrier is first impregnated with the alkali solution and then the contacted with solution A to form a catalyst precursor, and wherein the total amount of the alkali solution and solution A is a mass of at least 1.1 times and no greater than 10.0 times the amount of water absorption of the carrier. A catalyst for alkenyl acetate production is obtained that exhibits improved activity and selectivity.