Epoxidation Catalyst Post-Conditioning Chloride Adsorption
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Solution Overview
Problem
Current methods for activating Re-containing epoxidation catalysts in ethylene oxide production require lengthy conditioning processes, including high temperatures and chloride pre-soaking, which delay production and may not fully realize the potential selectivity benefits of high-selectivity catalysts.
Innovation Solution
A method involving a post-conditioning step with a high chloride concentration at lower temperatures (215°C - 225°C) followed by a reduction to normal chloride levels, optimizing catalyst performance by enhancing chloride adsorption and maintaining selectivity and stability over the catalyst's life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional conditioning procedures with chloride pre-soaking at temperatures below operating temperature are used, then catalyst selectivity is improved, but production time is significantly delayed
Solution Approach 1:
The patent applies preliminary action by pre-chlorinating the catalyst at elevated temperatures (200-400°C) before introducing oxygen into the feed. This preliminary chlorination step ensures the catalyst has adequate chloride content before the main epoxidation reaction begins, eliminating the need for prolonged low-temperature pre-soaking and reducing production delays while maintaining selectivity.
Solution Approach 2:
The patent changes the temperature parameter from traditional low-temperature pre-soaking (below operating temperature) to elevated temperature conditioning (200-400°C). This parameter change accelerates the chlorination process and reduces the conditioning time required while achieving the same or better selectivity performance, thereby reducing production delays.
2Reliability
If high temperatures are used during catalyst conditioning, then catalyst activation is achieved, but energy consumption increases
Solution Approach 1:
The patent uses periodic action by implementing a multi-stage heating process where the temperature is increased in steps (e.g., from ambient to 200°C, then to 400°C) rather than applying maximum temperature continuously. This staged approach reduces peak energy consumption while still achieving proper catalyst activation and chlorination.
Solution Approach 2:
The patent performs preliminary chlorination at elevated temperatures before the main reaction, which activates the catalyst more efficiently. This preliminary action at controlled temperatures achieves reliable catalyst activation without requiring excessive energy input during the main production phase.
3Manufacturing precision
If chloride concentration is increased to enhance catalyst performance, then selectivity is improved, but production cost increases
Solution Approach 1:
The patent introduces chloride compounds (such as ethylene dichloride, 1,2-dichloroethane, or methyl chloride) during the preliminary conditioning phase before oxygen introduction. This preliminary addition ensures adequate chloride content on the catalyst surface for high selectivity without requiring high chloride concentrations during the main production phase, thereby reducing overall chloride consumption and cost.
Solution Approach 2:
The patent dynamically adjusts chloride concentration over time - higher concentrations are used during the conditioning phase to build up chloride content on the catalyst, then lower concentrations are maintained during production. This dynamic approach maintains high selectivity while minimizing chloride consumption and associated costs.
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
This approach improves both instantaneous and average selectivity and stability of the catalyst, overcoming the limitations of traditional conditioning methods by achieving superior catalyst performance with reduced delays in production.
Implementation Method 1
contacting a fresh epoxidation catalyst with a feed gas composition containing a small amount of chloride at a temperature of about 200°C to about 400°C for a period of time until the catalyst has absorbed an optimal amount of chloride
Data Source
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AI summary
A method for the epoxidation of an olefin comprising the steps of reacting a feed gas composition containing an olefin, oxygen, and a moderator having a post-conditioning step where the catalyst is exposed to reactor feed having a chlorides concentration of from about 5 ppm to about 7 ppm and at a temperature of about 215°C to about 225°C.