Cobalt Catalyst Shrinkage for Reactor Unloading

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Solution Overview

Problem

The existing processes for unloading catalyst particles from reactor tubes, especially those with larger sizes or swollen catalysts, are inefficient and time-consuming, particularly in Fischer Tropsch processes where catalysts comprise metal oxides and cobalt.

Innovation Solution

A process involving feeding a gas with 10-30% oxygen at controlled conditions to the reactor tube, allowing the catalyst particles to shrink, facilitating easier removal by oxidizing metallic cobalt to cobalt oxide, thereby reducing particle size and simplifying the unloading process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If catalyst particles are used in Fischer Tropsch process, then catalytic activity is achieved, but catalyst particles swell and become difficult to remove from reactor tube

Engineering Contradiction:
Improvecatalytic activityVSAvoidease of catalyst removal
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies parameter changes by oxidizing metallic cobalt to cobalt oxide, which changes the physical and chemical parameters of the catalyst particles. This oxidation causes the swollen catalyst particles to shrink, transforming them from a difficult-to-remove state to an easily removable state while preserving catalytic functionality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses strong oxidants (oxygen-containing gas) to accelerate the oxidation of metallic cobalt to cobalt oxide. This accelerated oxidation process efficiently shrinks the swollen catalyst particles, enabling their removal from the reactor tube after use

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

2Reliability

If catalyst particles swell during use, then catalytic function is maintained, but unloading time increases significantly

Engineering Contradiction:
Improvecatalytic functionVSAvoidunloading time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing oxidation of the catalyst particles before the unloading step. By oxidizing the metallic cobalt to cobalt oxide in advance, the catalyst particles shrink and become easier to remove, significantly reducing the actual unloading time from the reactor tube

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The oxidation process changes the physical parameters of the catalyst particles, causing swollen particles to shrink. This parameter change transforms the catalyst from a bulky, difficult-to-remove state to a compact, easily removable state, thereby reducing unloading time

Inventive Principle:
Principle #35Parameter changes

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 process significantly reduces the time required for unloading catalyst particles by causing swollen particles to shrink, making the removal more efficient, especially for catalysts with larger sizes or those that have swollen during use.

Implementation Method 1

allowing the catalyst particles to shrink, facilitating easier removal by oxidizing metallic cobalt to cobalt oxide

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentUS9566570B2Process for catalyst unloading facilitation
Publication Date: 2017.02.14 SHELL USA INC

AI summary

A process for facilitating the unloading of a fixed bed of cobalt/metal oxide catalyst particles from a reactor tube by (i) feeding a gas comprising 10 to 30 (vol/vol) percent of oxygen to the reactor tube with a GHSV for oxygen of 0.5 to 50 Nl/l/hr, and (ii) removing the catalyst particles from the reactor tube. In the fixed bed of catalyst particles to which the oxygen comprising gas is fed in step (i) at most 10 mole % of the element cobalt is present in Co3O4 and/or CoO, calculated on the total amount of moles of cobalt in the catalyst particles.