Scavenger Pre-treatment for Polymerization Reactor Cleaning

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Solution Overview

Problem

The challenge in polymerization processes is the rapid and abrupt increase in polymerization reaction speed due to high catalyst concentrations, leading to localized hot spots, agglomeration, and changes in polymer properties, especially when starting up after reactor cleaning or maintenance, where catalyst poisons like water can introduce impurities and require extensive drying procedures.

Innovation Solution

Introducing a scavenger, such as metal alkyls like triethylaluminium, into the reactor to react with catalyst poisons before catalyst introduction, controlling the level of decomposition products to ensure complete poison neutralization and optimal scavenger levels between 0.1 and 2.5 moles per ton of charge powder, allowing for immediate and stable polymerization startup without agglomerates or fouling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If extensive drying procedures are performed to remove catalyst poisons, then polymer purity is improved, but loss of time increases

Engineering Contradiction:

Improvepolymer purityVSAvoiddrying time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by introducing the scavenger compound into the reactor before the polymerization reaction starts. This pre-treatment allows the scavenger to react with and remove catalyst poisons (water, oxygen) in advance, so that when polymerization begins, the catalyst is already protected and can operate immediately at full efficiency without requiring extensive pre-drying procedures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The scavenger compound acts as an intermediary substance between the catalyst and catalyst poisons. It selectively reacts with harmful impurities (water, oxygen) to form harmless byproducts, thereby protecting the catalyst from deactivation and enabling immediate polymerization without prolonged drying times.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If high concentration of catalyst system is used to compensate for delay, then productivity is improved, but temperature control worsens leading to hot spots

Engineering Contradiction:

Improvepolymerization speedVSAvoidhot spot formation

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The scavenger is introduced in advance to eliminate catalyst poisons before the high-concentration catalyst addition. This preliminary purification ensures that when the catalyst is introduced at high concentration for rapid polymerization, it operates efficiently and uniformly without localized deactivation that would create hot spots and agglomeration.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The scavenger performs a preliminary anti-action by neutralizing catalyst poisons (water and oxygen) before they can interfere with the catalyst system. This pre-protection allows the use of high catalyst concentrations for improved productivity without the risk of uncontrolled hot spot formation, as the catalyst remains stable and evenly distributed.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If reactor cleaning operations are performed, then reliability is improved, but object-generated harmful factors increase due to introduced impurities

Engineering Contradiction:

Improvereactor operation reliabilityVSAvoidcatalyst poisons introduction

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of cleaning operations (introduction of water and oxygen impurities) into a benefit by using the scavenger compound. The scavenger is specifically designed to react with these introduced impurities, transforming them from harmful catalyst poisons into harmless reaction products, thereby maintaining catalyst activity and polymerization reliability despite necessary cleaning operations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The scavenger compound serves as an intermediary that bridges the gap between reactor cleaning operations and catalyst protection. It is introduced into the reactor to selectively react with and neutralize impurities (water, oxygen) that are inevitably introduced during cleaning, thereby protecting the catalyst system and ensuring reliable polymerization operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables immediate and stable polymerization startup with consistent polymer properties, reducing the risk of agglomeration and fouling, and optimizing the cleaning/drying process by controlling scavenger levels, thus ensuring efficient reactor operation and desired product quality.

Implementation Method 1

introducing a scavenger, such as metal alkyls like triethylaluminium, into the reactor to react with catalyst poisons

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

controlling the level of decomposition products to ensure complete poison neutralization

Methodology Applied

Scientific EffectDecomposition: Decomposition (biological)

Data Source

PatentEP3044237B1Process for the (co-)polymerisation of olefins

Publication Date: 2018.02.21 INEOS EUROPE AG

AI summary

The present invention relates to a process for improving cleaning and/or drying of a polymerisation reactor by adding a compound that reacts with the catalyst poisons to scavenge it.