Rectification Column Acrylic Acid Polymerization Inhibition

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Solution Overview

Problem

The existing processes for separating acrylic acid and methacrylic acid from reaction gas mixtures in heterogeneously catalyzed gas phase oxidation are hindered by the presence of precursor aldehydes like acrolein and methacrolein, which increase polymerization tendencies, and acetone, which is assumed to promote polymerization, leading to inefficiencies and additional material requirements.

Innovation Solution

A process that rectificatively separates liquids with at least 10% acrylic acid or methacrylic acid by weight, enriched with acetone to exceed 15% by weight based on acrolein and methacrolein, using a rectification column with specific catalyst selection, absorption, and desorption conditions to manage acetone levels and inhibit polymerization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional rectification processes are used to separate acrylic acid and methacrylic acid from reaction gas mixtures, then separation is achieved, but polymerization occurs due to the presence of precursor aldehydes (acrolein and methacrolein)

Engineering Contradiction:
Improveseparation efficiencyVSAvoidpolymerization control
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent extracts and removes the harmful precursor aldehydes (acrolein and methacrolein) from the liquid mixture before rectification. This is achieved through selective absorption or chemical treatment that specifically targets and eliminates the aldehydes while preserving the acrylic acid and methacrylic acid, thereby preventing polymerization during the separation process

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary treatment steps before rectification to modify the composition of the liquid mixture. By pre-removing or pre-modifying the precursor aldehydes through absorption, chemical reaction, or other preparatory processes, the system prevents polymerization from occurring during the subsequent rectification operation

Inventive Principle:
Principle #10Preliminary action

2Reliability

If acetone is present in the liquid mixture during rectification, then it is assumed to promote polymerization, but removing acetone requires additional materials and process complexity

Engineering Contradiction:
Improvepolymerization inhibitionVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the removal of acetone with the removal or management of precursor aldehydes into a single integrated process step. By using a multifunctional treatment approach that simultaneously addresses both acetone and aldehyde concentrations, the system achieves polymerization inhibition without requiring separate complex processing stages for each component

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a universal treatment method that handles multiple harmful components (acetone, acrolein, methacrolein) through a single process mechanism. The selected approach是否具有 universal applicability to remove or manage various volatile organic compounds that promote polymerization, thereby simplifying the overall process design

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If external acetone is added to enrich the liquid mixture, then polymerization is inhibited, but material costs and external addition requirements increase

Engineering Contradiction:
Improvepolymerization resistanceVSAvoidacetone loss
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent enables the system to generate the required acetone enrichment internally through the rectification process itself, rather than requiring external addition. By carefully controlling the rectification parameters and utilizing the natural distribution of components, the process produces an acetone-enriched fraction that can be recycled back into the system, achieving self-sufficiency and eliminating external material inputs

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent recycles the acetone-enriched fraction obtained during rectification back into the process system. Instead of discarding this fraction as waste or requiring continuous external acetone addition, the system recovers and reuses it to maintain polymerization inhibition, thereby reducing material losses and external requirements

Inventive Principle:
Principle #34Discarding and recovering

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 effectively reduces polymerization risks and enhances the separation efficiency of acrylic acid and methacrylic acid, allowing for higher acetone enrichment without external addition, thereby minimizing losses and costs.

Implementation Method 1

conducting the liquid II into a rectification column

Methodology Applied
Scientific EffectFractional distillation: Distillation

Implementation Method 2

a polymerization-inhibiting action can be ascribed to acetone in the above context

Methodology Applied
Scientific EffectFree-radical polymerization inhibition:

Data Source

PatentUS7323590B2Process for rectificatively separating a liquid comprising acrylic acid and/or methacrylic acid
Publication Date: 2008.01.29 BASF SE

AI summary

A process for rectificatively separating a liquid which comprises acrylic acid, methacrylic acid or a mixture thereof, and additionally comprises low molecular weight aldehydes and acetone.