Chelating Agent Addition in Olefin Epoxidation Catalyst Protection
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Solution Overview
Problem
During extended operation of continuous olefin epoxidation processes, deposits form on the catalyst, reducing activity and causing liquid maldistribution and uneven temperature profiles, which impairs selectivity, and these deposits are not effectively removed by standard regeneration procedures.
Innovation Solution
Adding a chelating agent to the aqueous hydrogen peroxide solution before mixing it with the solvent reduces or prevents the formation of deposits on the titanium zeolite catalyst, maintaining catalyst activity and ensuring even liquid distribution by passing a mixture of olefin, solvent, and hydrogen peroxide with the added chelating agent through a fixed bed of a titanium zeolite catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous epoxidation is carried out using a fixed bed titanium silicalite catalyst, then high reaction rate and product selectivity are achieved, but deposits form on the catalyst during extended operation, reducing catalyst activity and causing liquid maldistribution
Solution Approach 1:
A chelating agent is added to the aqueous hydrogen peroxide solution before it is mixed with the organic solvent and fed to the reactor. This preliminary action prevents deposit formation on the catalyst surface before the deposits can interfere with the reaction, thereby maintaining catalyst activity during extended operation while preserving the high reaction rate
Solution Approach 2:
A chelating agent acts as an intermediary substance that binds to metal ions in the hydrogen peroxide solution, preventing these ions from forming deposits on the catalyst surface. This intermediary approach allows the continuous epoxidation to proceed without the harmful deposit formation that would otherwise reduce catalyst activity
2Duration of action of moving object
If deposits accumulate on the catalyst, then catalyst activity is reduced and liquid maldistribution occurs, but standard regeneration procedures of washing with solvent or heating are ineffective
Solution Approach 1:
The chelating agent is introduced into the feed stream before the deposits can form on the catalyst, preventing the accumulation that would otherwise require difficult regeneration procedures. This preliminary prevention allows the process to run for extended periods without regeneration while avoiding the formation of irreovable deposits
Solution Approach 2:
Instead of attempting to remove harmful deposits after they form, the chelating agent converts the potential harmful interaction between metal ions and catalyst surface into a beneficial chelate complex that remains in solution, thereby preventing deposit formation and eliminating the need for complex regeneration procedures
3Reliability
If deposits form at the orifices of the liquid distributor, then blocking occurs leading to maldistribution of liquid to individual tubes, but adding chelating agent to the mixture after solvent mixing is less effective
Solution Approach 1:
The chelating agent is added to the aqueous hydrogen peroxide solution before mixing with the organic solvent, ensuring that metal ions are chelated before they can interact with the solvent system and form deposits at the distributor orifices. This timing is critical for preventing blocking and maintaining uniform liquid distribution
Solution Approach 2:
The order of addition and the timing of chelating agent introduction are changed as a process parameter to optimize its effectiveness. By adding the chelating agent before solvent mixing rather than after, the process ensures maximum prevention of deposit formation at critical locations like distributor orifices
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 addition of a chelating agent significantly reduces deposit formation, maintaining catalyst activity and preventing liquid maldistribution, thereby enhancing the selectivity and efficiency of the epoxidation process.
Implementation Method 1
adding a chelating agent to the aqueous hydrogen peroxide solution before mixing it with solvent reduces or prevents the formation of deposits on the titanium zeolite catalyst
Implementation Method 2
a fixed bed of an epoxidation catalyst comprising a titanium zeolite
Data Source
AI summary
In a process for the epoxidation of an olefin with hydrogen peroxide in the presence of a solvent, where a mixture comprising olefin,an aqueous hydrogen peroxide solution and a solvent is continuously passed through a fixed bed of an epoxidation catalyst comprising a titanium zeolite, addition of a chelating agent to the aqueous hydrogen peroxide solution before mixing it with solvent reduces or prevents formation of deposits on the catalyst and blocking of orifices of a liquid distributor.