Surfactant-Modified Silver Catalyst Preparation for Ethylene Epoxidation
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Solution Overview
Problem
The existing process for preparing silver-containing catalysts for ethylene epoxidation is hindered by excess silver impregnation solution clinging to the carrier surfaces, leading to silver losses, equipment fouling, and reduced catalyst performance due to agglomeration of silver particles with low surface areas.
Innovation Solution
Incorporating surfactants into the silver impregnation solution to improve drainage and selectively remove excess solution from the carrier surfaces, reducing silver consumption by up to 15% without compromising catalyst performance, and using centrifugation to control silver particle size and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If silver-containing impregnation solution is applied to the carrier support, then the catalyst is formed, but excess solution clings to the external surfaces causing silver losses and equipment fouling
Solution Approach 1:
The patent changes the physical-chemical parameters of the impregnation solution by adding surfactants (surface-active agents) to reduce surface tension. This parameter change modifies the wetting and drainage characteristics of the solution, allowing excess solution to drain more effectively from the carrier exterior surfaces while maintaining adequate impregnation of the pores, thereby reducing silver loss.
Solution Approach 2:
The patent introduces surfactants as intermediary substances that mediate between the impregnation solution and the carrier support. These surfactants act as intermediaries that reduce surface tension and improve drainage characteristics, enabling the solution to be more easily removed from external surfaces without compromising the impregnation process.
2Reliability
If excess impregnation solution remains on the carrier surface, then complete impregnation is achieved, but silver agglomerates form with low surface area reducing catalyst activity
Solution Approach 1:
The patent changes the surface tension parameter of the impregnation solution by adding surfactants. This parameter change controls the drainage behavior, allowing the solution to drain from external surfaces while remaining in the pores. This results in more uniform silver particle distribution and prevents agglomeration, maintaining high surface area and catalyst activity.
Solution Approach 2:
The patent creates local quality differences in the distribution of impregnation solution by controlling drainage. The surfactants enable the solution to be selectively retained in the pore regions while being removed from external surfaces, creating a non-uniform distribution that prevents agglomeration and maintains high surface area silver particles.
3Reliability
If mesh belt calcination is used to heat treat the catalyst, then the silver is reduced and activated, but excess solution transfers to the belt causing blockages and requiring shutdowns
Solution Approach 1:
The patent changes the surface tension and drainage characteristics of the impregnation solution by adding surfactants. This parameter change reduces the amount of excess solution on the carrier exterior before calcination, thereby minimizing transfer to the mesh belt and preventing blockages that would require shutdowns for cleaning.
Solution Approach 2:
The patent applies preliminary anti-action by modifying the impregnation solution with surfactants before the calcination step. This preliminary modification prevents the harmful effect of solution transfer to the mesh belt by improving drainage and reducing surface tension, thereby avoiding equipment fouling before it occurs.
4Manufacturing precision
If more impregnation solution is used to ensure complete coverage, then uniform catalyst distribution is achieved, but silver consumption increases by up to 15%
Solution Approach 1:
The patent changes the surface tension parameter of the impregnation solution by adding surfactants. This parameter change improves drainage characteristics, allowing the solution to be more efficiently distributed and retained where needed (in the pores) while draining from excess locations (external surfaces). This achieves uniform catalyst distribution with reduced silver consumption of up to 15%.
Solution Approach 2:
The patent introduces surfactants as intermediary substances that enable more efficient use of the impregnation solution. These intermediaries improve the distribution and retention characteristics, ensuring uniform catalyst distribution throughout the carrier pores while minimizing waste and silver consumption.
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 enhances silver utilization, simplifies catalyst handling, reduces dust and debris, and improves reactor performance by maintaining consistent pressure drops and reducing plant turnaround times, while maintaining or improving catalyst activity and selectivity.
Implementation Method 1
the addition of various surfactants into the silver impregnation solution can improve its drainage from the carrier exteriors during the catalyst synthesis
Implementation Method 2
using centrifugation to control silver particle size and distribution
Data Source
AI summary
A process for preparing a silver-containing catalyst for the oxidation of ethylene to ethylene oxide (EO) including the steps of: providing a support having pores; providing a silver-containing impregnation solution; adding an amount of surfactant to the impregnation solution; contacting the support with the surfactant-containing impregnation solution; and removing at least a portion of the impregnation solution prior to fixing the silver upon the carrier in a manner which preferentially removes impregnation solution not contained in the pores. The use of the surfactant results in improved drainage of the silver impregnation solution from the carrier exteriors during the catalyst synthesis. As a result, the amount of silver-containing impregnation solution necessary for the synthesis of the EO catalyst was reduced by up to 15% without reducing the catalyst performance.