Ethylene Oxide Catalyst with Tungsten Stabilizer
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Solution Overview
Problem
Existing catalysts for producing ethylene oxide face challenges in achieving both high selectivity and catalytic life (durability), with rhenium-based catalysts experiencing migration and aggregation issues, leading to reduced performance over time.
Innovation Solution
A catalyst comprising silver, cesium, rhenium, and tungsten or molybdenum supported on a carrier with a specific surface area of 0.5 to 1.3 m^2/g, Si content of 0.1 to 5.0% by mass, and Na content of 0.05 to 1.0% by mass, which inhibits the migration and aggregation of rhenium and tungsten or molybdenum, thereby improving catalytic life and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rhenium is added as a catalyst component to improve selectivity, then catalytic selectivity is improved, but catalyst durability decreases due to migration and aggregation of rhenium
Solution Approach 1:
The patent introduces tungsten or molybdenum as an intermediary substance that mediates between rhenium and the carrier. This intermediary prevents direct harmful interactions between rhenium and the carrier surface, thereby inhibiting rhenium migration and aggregation while preserving the selectivity-enhancing properties of rhenium.
Solution Approach 2:
The patent creates a composite catalyst system comprising silver, cesium, rhenium, and tungsten or molybdenum on a specific carrier. This composite structure leverages the synergistic effects of multiple components where tungsten or molybdenum stabilizes rhenium, allowing the system to achieve both high selectivity and durability that individual components cannot provide alone.
2Productivity
If carrier surface area is increased to support more silver, then catalytic activity is improved, but selectivity decreases due to sequential oxidation reaction in fine pores
Solution Approach 1:
The patent optimizes the carrier surface area parameter to a specific range (0.5 to 1.3 m²/g) rather than simply maximizing it. This parameter change balances the competing requirements: providing sufficient surface area to support adequate silver for high activity while limiting the surface area to prevent excessive fine pore formation that would lead to sequential oxidation and reduced selectivity.
3Manufacturing precision
If rhenium content is increased to improve selectivity, then catalytic selectivity is improved, but catalyst life decreases due to easier migration and aggregation
Solution Approach 1:
The patent introduces tungsten or molybdenum as an intermediary substance that mediates between rhenium and the carrier. This intermediary prevents direct harmful interactions between rhenium and the carrier surface, thereby inhibiting rhenium migration and aggregation while preserving the selectivity-enhancing properties of rhenium.
Solution Approach 2:
The patent creates a composite catalyst system comprising silver, cesium, rhenium, and tungsten or molybdenum on a specific carrier. This composite structure leverages the synergistic effects of multiple components where tungsten or molybdenum stabilizes rhenium, allowing the system to achieve both high selectivity and durability that individual components cannot provide alone.
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 selectivity and extended catalytic life, allowing for efficient production of ethylene oxide over a long period, reducing the need for raw materials and lowering production costs.
Implementation Method 1
Production of ethylene oxide by catalytic gas-phase oxidation of ethylene with a molecular-oxygen-containing gas in the presence of a silver catalyst
Implementation Method 2
a carrier having specific surface area of 0.5 to 1.3 m2/g, Si content (SiO2 equivalent) of 0.1 to 5.0% by mass and Na content (Na2O equivalent) of 0.05 to 1.0% by mass, which inhibits the migration and aggregation of rhenium and tungsten or molybdenum
Implementation Method 3
catalytic gas-phase oxidation of ethylene with a molecular-oxygen-containing gas
Data Source
AI summary
PROBLEMThere is provided a catalyst for producing ethylene oxide which is superior in catalytic selectivity and catalytic life (durability).SOLUTIONThere is provided a catalyst for producing ethylene oxide having a catalyst component supported on a carrier, wherein the carrier has specific surface area of 0.5 to 1.3 m2/g, Si content (SiO2 equivalent) of 0.1 to 5.0% by mass and Na content (Na2O equivalent) of 0.05 to 1.0% by mass, and the catalyst component is silver (Ag), cesium (Cs), rhenium (Re) and tungsten (W) or molybdenum (Mo).