Supported Silver Catalyst Resilience to Reactor Upsets
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Solution Overview
Problem
Supported silver catalysts prepared with high-purity alpha-alumina carriers face challenges in recovering from reactor upsets, leading to permanent losses in activity and efficiency, especially when operating at high workrates.
Innovation Solution
A supported silver catalyst is produced using a high-purity alpha-alumina carrier with specific promoter combinations, including cesium, sodium, and manganese, which enhances resilience and stability, allowing for timely recovery of activity and efficiency after reactor upsets and maintains high productivity even at high workrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-purity alpha-alumina carriers are used to improve catalyst activity and efficiency, then catalyst productivity is enhanced, but the catalyst's ability to recover from reactor upsets deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the catalyst by introducing specific promoter combinations (cesium at 0.01-0.5 wt%, sodium at 0.001-0.05 wt%, and manganese at 0.001-0.1 wt%) onto the high-purity alpha-alumina carrier. This parameter change resolves the contradiction by enhancing the catalyst's resilience to reactor upsets while preserving the high productivity benefits of the pure carrier
Solution Approach 2:
The patent creates a composite catalyst structure by depositing multiple promoter species (cesium, sodium, and manganese) onto the alpha-alumina carrier. This composite approach combines the high productivity advantage of pure alpha-alumina with the upset-resistance properties provided by the promoter combination, particularly manganese which stabilizes the catalyst during reactor upsets
2Duration of action of stationary object
If reactor upsets occur during operation, then temporary shutdowns happen, but permanent loss of catalyst activity and efficiency occurs
Solution Approach 1:
The patent applies beforehand cushioning by pre-loading the catalyst with specific promoter combinations (particularly manganese along with cesium and sodium) before reactor operation begins. This preparatory step creates a protective chemical environment that cushions the catalyst against the damaging effects of reactor upsets, preventing permanent activity loss that would otherwise occur during shutdowns
3Productivity
If high workrates are maintained to maximize productivity, then output increases, but catalyst stability and recovery capability decrease
Solution Approach 1:
The patent optimizes the concentration parameters of promoter species deposited on the carrier, specifically setting cesium at 0.01-0.5 wt%, sodium at 0.001-0.05 wt%, and manganese at 0.001-0.1 wt%. This precise parameter control allows the catalyst to maintain high workrate productivity while the promoter composition stabilizes the catalyst structure against degradation at elevated operating conditions
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 exhibits improved activity and stability, recovering to pre-upset levels within 3 days and maintaining high ethylene oxide production efficiency, even under conditions of reactor upsets, with selectivity to ethylene oxide exceeding 87% at elevated workrates.
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
Implementation Method 2
the combination of cesium and other alkali metals exhibits a synergistic promoting effect on the oxidation process
Data Source
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AI summary
A supported silver catalyst and use thereof in a process for producing an alkylene oxide, such as ethylene oxide, by the direct oxidation of an alkylene with oxygen or an oxygen-containing gas, wherein the catalyst provides improved stability and improved resilience to reactor upsets and timely recovery to substantially pre-upset levels of catalyst activity and/or efficiency. In some embodiments, the catalyst also exhibits improved activity. A catalyst capable of producing ethylene oxide at a selectivity of at least 87 percent while achieving a work rate of at least 184 kg/h/m3 at a temperature of no greater than 235°C when operated in a process where the inlet feed to a reactor containing the catalyst comprises ethylene, oxygen, and carbon dioxide, wherein the concentration of carbon dioxide in the inlet feed is greater than or equal to 2 mole percent.