Polyisocyanate Production from Waste Polyurethane via Closed-Loop Phosgene

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Solution Overview

Problem

Existing processes for preparing polyisocyanates have limited sustainability and environmental impact, necessitating the development of more sustainable and cost-effective methods.

Innovation Solution

A process involving the solvolysis of solid polyurethane materials to produce polyamines, followed by CO2 reduction to CO, which is used in phosgene synthesis, ultimately producing polyisocyanates like TDI or MDI, utilizing waste materials and reducing environmental footprint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional phosgenation processes are used to prepare polyisocyanates, then production efficiency is maintained, but environmental impact increases due to HCl by-product formation and limited sustainability

Engineering Contradiction:

Improveenvironmental impactVSAvoidproduction efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The process converts HCl, traditionally a harmful by-product requiring disposal or complex recovery, into a valuable intermediate for phosgene synthesis through catalytic oxidation. This transforms an environmental liability into a useful chemical feedstock, eliminating waste while maintaining productive output.

Inventive Principle:

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

Solution Approach 2:

The process recovers and循环利用 HCl generated in the polyisocyanate synthesis step, converting it back to chlorine and then to phosgene. This closed-loop approach prevents HCl discharge into the environment while ensuring continuous supply of phosgene for production, simultaneously addressing environmental and productivity concerns.

Inventive Principle:

Principle #34Discarding and recovering

2Object-affected harmful factors

If sustainable processes using renewable materials are implemented, then environmental sustainability improves, but process complexity increases

Engineering Contradiction:

ImprovesustainabilityVSAvoidprocess complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The process merges multiple functions into integrated reaction zones: the first reaction zone simultaneously performs polyamine synthesis and generates HCl, while the second zone converts this HCl to phosgene. This consolidation creates a compact, self-sufficient system that achieves sustainability without proportionally increasing complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

HCl serves as an intermediary substance that connects the polyamine synthesis step with the phosgene production step. Rather than treating HCl as waste to be removed, the process uses it as a bridge between reaction stages, simplifying the overall material flow and reducing the need for separate waste treatment systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If HCl recovery processes are implemented to reduce environmental impact, then sustainability improves, but additional processing steps increase complexity

Engineering Contradiction:

Improveenvironmental impactVSAvoidprocessing steps

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The process establishes continuous action where HCl generated in one step flows directly into the oxidation reactor for conversion to chlorine, which then feeds the phosgene synthesis. This continuous material flow eliminates discrete recovery and disposal steps, maintaining sustainability through seamless integration rather than additional processing stages.

Inventive Principle:

Principle #20Continuity of useful 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 process achieves improved sustainability and cost-effectiveness by recycling waste polyurethane materials and minimizing environmental impact while producing high-quality polyisocyanates.

Implementation Method 1

passing and subjecting W provided according to (i) to solvolysis reaction conditions into a solvolysis zone RS comprising one or more reactor units, obtaining a stream SPA comprising the corresponding at least one polyamine, a stream SL comprising at least one polyol and a stream S1 comprising CO2

Methodology Applied

Scientific EffectSolvolysis:

Implementation Method 2

passing S1 obtained according to (ii) through a CO2-reduction unit UR, obtaining a stream SCO comprising CO

Methodology Applied

Scientific EffectCO2 reduction:

Implementation Method 3

passing SCO obtained according to (iii) into a reaction unit for preparing phosgene RUP and contacting SCO with S2 obtained according to (iv.1) into RUP, obtaining a stream S3 comprising phosgene

Methodology Applied

Scientific EffectPhosgene synthesis:

Implementation Method 4

passing the at least one polyamine obtained according to (ii) as SPA into a reaction unit RU and reacting SPA with phosgene comprised in S3 obtained according to (iv.2), obtaining a stream SP comprising the corresponding at least one polyisocyanate

Methodology Applied

Scientific EffectPhosgenation reaction:

Data Source

PatentEP4403589B1A process for preparing at least one polyisocyanate from solid material w

Publication Date: 2026.04.15 BASF SE

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AI summary

The present invention relates to a process for preparing at least one polyisocyanate from a solid material W. The present invention further relates to a production unit for carrying out the aforementioned process as well as a polyisocyanate obtainable or obtained according to the aforementioned process.