Ethylene Oxide Catalyst Carrier Sodium Removal

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Solution Overview

Problem

Existing carrier treatment processes for ethylene oxide catalysts are limited in effectively removing sodium from the surface and subsurface, leading to catalyst degradation, and there is a need for improved stability and longevity of the catalyst.

Innovation Solution

A method involving successive rinsing with water to achieve a steady state in sodium content, monitored by electrical conductivity, which depletes surface and subsurface sodium, ensuring the carrier has a sodium content of 20 ppm or less, thereby enhancing the stability and longevity of the silver-based ethylene oxide catalyst.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional carrier treatment processes are used, then the carrier can be prepared for catalyst application, but sodium content remains high on the surface and subsurface leading to catalyst degradation

Engineering Contradiction:

Improvecatalyst stabilityVSAvoidsodium content on carrier

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by treating the carrier with water to remove sodium before the catalyst is applied. The treatment process removes sodium from the surface and subsurface of the carrier, preventing sodium from migrating to the catalyst surface during operation and causing degradation. This pre-treatment ensures the carrier is ready for catalyst application in a sodium-free state.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies the extraction principle by using water to leach and remove sodium from the carrier surface and subsurface. The water treatment process extracts sodium ions from the carrier, achieving a sodium content of less than 10 ppm on the surface, which prevents subsequent sodium migration that would harm catalyst performance.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If successive water rinsing is performed to remove sodium, then catalyst stability is improved, but treatment time and process complexity increase

Engineering Contradiction:

Improvecatalyst longevityVSAvoidcarrier treatment time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies feedback by monitoring the electrical conductivity of the rinse water during successive water treatments. As sodium is removed from the carrier, the conductivity of the rinse water decreases. The treatment continues until a predetermined conductivity threshold is reached, providing an objective endpoint criterion that optimizes treatment time while ensuring sufficient sodium removal for catalyst stability.

Inventive Principle:

Principle #23Feedback

3Productivity

If sodium is not removed from the carrier, then the carrier can be used immediately for catalyst preparation, but the catalyst will degrade faster due to sodium migration

Engineering Contradiction:

Improvecatalyst preparation efficiencyVSAvoidcatalyst usable life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary action by removing sodium from the carrier before catalyst preparation and application. This pre-treatment, while adding a processing step, prevents subsequent catalyst degradation and extends catalyst life, ultimately improving overall productivity by reducing catalyst replacement frequency and maintaining stable ethylene oxide production over time.

Inventive Principle:

Principle #10Preliminary action

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 method significantly extends the usable lifetime of the catalyst by reducing sodium content, leading to improved stability and selectivity, with selectivity values of at least 83 mol % up to 93 mol % in ethylene oxide production.

Implementation Method 1

contacting a carrier with water; recovering a rinse solution from the contacting of the carrier with the water, the rinse solution comprises leached sodium from the carrier

Methodology Applied

Scientific EffectLeaching: Solvation

Implementation Method 2

determining sodium content in the rinse solution

Methodology Applied

Scientific EffectElectrical conductivity measurement: Conduction (electrical)

Data Source

PatentUS10669247B2Carrier treatment to improve catalytic performance of an ethylene oxide catalyst

Publication Date: 2020.06.02 SCIENTIFIC DESIGN CO LTD

AI summary

A method for lowering the sodium content of different carriers which may have different physical properties as well as varying degrees of sodium is provided. The method, which lowers the sodium content from the surface, subsurface as well as the binding layer of the carrier, includes contacting a carrier with water. A rinse solution is recovered from the contacting. The rinse solution includes leached sodium from the carrier. The sodium content in the rinse solution is then determined. The contacting, recovering and determining are repeated until a steady state in the sodium content is achieved.