Supported Silver Catalyst for Ethylene Oxide with Promoters
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Solution Overview
Problem
Existing silver catalysts for producing ethylene oxide from ethylene and oxygen require high silver content and multiple impregnation steps, increasing production costs and reducing efficiency, while also facing challenges in maintaining activity and selectivity with lower silver loads.
Innovation Solution
A supported silver catalyst with a silver content of less than 25% by weight, utilizing a high-purity alumina carrier with carefully tailored amounts of alkali and oxyanion promoters such as cesium, sulfate, rhenium, sodium, and optionally lithium, to maintain activity and selectivity levels comparable to higher silver content catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high silver content (greater than 30-35% by weight) is used in the catalyst, then activity and efficiency are improved, but manufacturing cost increases and production capacity decreases due to multiple impregnation steps
Solution Approach 1:
The invention changes the chemical composition parameters by introducing specific promoters (cesium at 0.1-1.0 wt%, sulfate at 0.5-5.0 wt%, and optionally rhenium at 0.01-0.5 wt%) to compensate for reduced silver content. This allows achieving comparable catalytic performance with lower silver loading (16-25 wt%), thereby reducing material cost and simplifying the manufacturing process to a single impregnation step.
Solution Approach 2:
The invention creates a composite catalyst system combining silver with multiple promoters (cesium, sulfate, and optionally rhenium and manganese) on an alumina support. This composite approach synergistically enhances catalytic activity and selectivity, allowing reduced silver content while maintaining or improving overall catalyst performance compared to high-silver conventional catalysts.
2Quantity of substance
If multiple impregnation steps are used to achieve high silver loading, then silver content is increased, but production capacity and manufacturing efficiency are reduced
Solution Approach 1:
The invention merges multiple impregnation steps into a single impregnation step by formulating a composite impregnation solution containing silver compound, cesium compound, sulfate source, and optionally rhenium and manganese compounds. This simultaneous deposition achieves the desired silver loading (16-25 wt%) along with optimal promoter distribution in one operation, dramatically increasing manufacturing productivity compared to sequential multiple impregnation steps.
Solution Approach 2:
The invention changes the manufacturing process parameters by optimizing the single-step impregnation conditions, including the composition of the impregnation solution, impregnation temperature, drying conditions, and calcination parameters. These optimized parameters enable complete silver deposition and promoter integration in one step, achieving both high silver content (16-25 wt%) and manufacturing efficiency.
3Ease of manufacture
If silver content is reduced to less than 25% by weight, then manufacturing cost and process complexity are reduced, but maintaining activity and selectivity becomes difficult
Solution Approach 1:
The invention changes the chemical composition parameters by precisely controlling the amounts of promoters: cesium (0.1-1.0 wt%), sulfate (0.5-5.0 wt%), rhenium (0.01-0.5 wt%), and manganese (0.01-0.1 wt%). These optimized promoter levels compensate for reduced silver content, maintaining catalytic activity and selectivity comparable to high-silver catalysts while enabling simpler, lower-cost manufacturing.
Solution Approach 2:
The invention develops a composite catalyst material where silver works synergistically with multiple promoters (cesium, sulfate, rhenium, and manganese) on an alumina support. This composite structure creates active sites with enhanced catalytic performance, allowing the system to achieve high activity and selectivity with reduced silver content (16-25 wt%), thereby resolving the trade-off between manufacturing ease and catalyst performance.
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 comparable activity and selectivity to higher silver content catalysts while reducing silver usage and simplifying the manufacturing process, offering improved efficiency and cost-effectiveness.
Implementation Method 1
The manufacture of ethylene oxide by the direct reaction of ethylene with oxygen or an oxygen-containing gas in the presence of a silver catalyst
Data Source
AI summary
A supported silver catalyst and use thereof in a process for producing an olefin oxide, such as ethylene oxide, by the direct oxidation of an alkylene with oxygen or an oxygen-containing gas, wherein the catalyst provides good catalyst activity and/or efficiency despite loading levels of silver in the range of 16 to 25%.