Olefin Epoxidation Shutdown Method for Oxygen Control
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Solution Overview
Problem
Current epoxidation reaction shutdown methods in industrial processes, particularly those using olefin oxide production, face challenges in maintaining oxygen levels and safety during the shutdown phase, as terminating the olefin feed first while maintaining hydrogen peroxide feed leads to increased oxygen formation, causing issues in olefin recovery and safety concerns.
Innovation Solution
A shutdown method where olefin and organic solvent are provided to the epoxidation zone for a period, forming a mixture essentially free of hydrogen peroxide, and then contacted with the heterogeneous epoxidation catalyst under reaction conditions, allowing for controlled effluent stream removal, thereby managing oxygen levels and ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If olefin feed is terminated first while maintaining hydrogen peroxide feed during shutdown, then hydrogen peroxide can be washed from the reactor, but oxygen concentration increases significantly causing safety issues and problems in olefin recovery
Solution Approach 1:
The shutdown process is divided into sequential stages: first terminating olefin feed while maintaining hydrogen peroxide feed for a predetermined period to allow catalyst washing, then terminating hydrogen peroxide feed. This segmentation prevents simultaneous termination of both feeds, which would cause oxygen concentration buildup and safety issues.
Solution Approach 2:
The method performs preliminary action by maintaining hydrogen peroxide feed for a predetermined time period after terminating olefin feed, before finally terminating hydrogen peroxide feed. This preliminary continuation of hydrogen peroxide feed ensures complete washing of the catalyst while preventing oxygen concentration increase.
2Device complexity
If both olefin and hydrogen peroxide feeds are stopped simultaneously during shutdown, then shutdown is simplified, but residues remain in the reactor requiring additional cleaning steps
Solution Approach 1:
The method implements preliminary action by maintaining hydrogen peroxide feed for a predetermined time period after terminating olefin feed. This ensures complete washing of the catalyst with hydrogen peroxide solution before final shutdown, preventing residue formation and eliminating the need for additional cleaning steps.
3Ease of manufacture
If hydrogen peroxide feed is maintained during shutdown to wash the catalyst, then catalyst cleaning is improved, but oxygen levels increase causing safety concerns
Solution Approach 1:
The shutdown process is segmented into two distinct phases: first phase maintains hydrogen peroxide feed while terminating olefin feed to enable catalyst washing; second phase terminates hydrogen peroxide feed after a predetermined time to prevent oxygen concentration buildup. This segmentation achieves both catalyst washing and safety.
Solution Approach 2:
The method performs preliminary catalyst washing with hydrogen peroxide solution for a predetermined time period before finally terminating hydrogen peroxide feed. This preliminary washing action ensures complete catalyst cleaning while the controlled timing prevents oxygen concentration increase and safety issues.
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 method effectively reduces oxygen concentration in the effluent stream during shutdown and restart, preventing safety issues and maintaining efficient olefin recovery, with oxygen levels remaining below 100% of normal run values.
Implementation Method 1
subjecting the reaction mixture to epoxidation reaction conditions in the epoxidation zone, thereby obtaining a mixture comprising olefin oxide and organic solvent
Data Source
AI summary
In a first aspect, the present invention relates to a shutdown method for a process for preparing an olefin oxide comprising a normal run stage, wherein the normal run stage comprises providing olefin, hydrogen peroxide and organic solvent into an epoxidation zone comprising an heterogeneous epoxidation catalyst, so that a reaction mixture comprising olefin, hydrogen peroxide and organic solvent is formed and subjecting the reaction mixture to epoxidation reaction conditions in the epoxidation zone, thereby obtaining a mixture comprising olefin oxide and organic solvent; wherein the shutdown method comprises (a) providing olefin and organic solvent for a period of time t1 to the epoxidation zone, so that a mixture is formed, which is essentially free of hydrogen peroxide; (b) contacting the mixture from (a) over t1 under epoxidation reaction conditions in the epoxidation zone with the heterogeneous epoxidation catalyst; (c) removing during t1 an effluent stream from the epoxidation zone, the effluent stream comprising olefin and organic solvent. In a second aspect, the present invention relates to a process for preparing an olefin oxide comprising a normal run stage and a shutdown stage, wherein the normal run stage comprises (A) providing olefin, hydrogen peroxide, water and organic solvent into an epoxidation zone comprising an heterogeneous epoxidation catalyst, so that a reaction mixture comprising olefin, hydrogen peroxide, water and organic solvent is formed; (B) subjecting the reaction mixture from (I) to epoxidation reaction conditions in the epoxidation zone, thereby obtaining a mixture comprising olefin oxide, water and organic solvent; (C) removing an effluent stream from the epoxidation zone, comprising olefin oxide, water and organic solvent; wherein the shutdown stage comprises steps (a), (b) and (c) as described with respect to the first aspect.