Acetic Acid Purification via Alkali Neutralization

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Solution Overview

Problem

Existing processes for producing acetic acid struggle to efficiently inhibit the increase in hydrogen iodide concentration and subsequent condensation in distillation columns, leading to corrosion and inefficiencies in acetic acid purification.

Innovation Solution

Incorporating an alkali component into the crude acetic acid stream before distillation in a second distillation column, where the alkali component is added either before feeding the column or at the same height level as the feed, effectively neutralizes hydrogen iodide, preventing its condensation and reducing corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional distillation processes are used to purify acetic acid, then acetic acid can be separated and collected, but hydrogen iodide concentration increases and condenses in the distillation column causing corrosion

Engineering Contradiction:

Improveacetic acid purification qualityVSAvoidhydrogen iodide condensation and corrosion

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

An alkali component (such as potassium carbonate, sodium hydroxide, or calcium hydroxide) is introduced as an intermediary substance into the distillation column. This alkali component reacts with hydrogen iodide to form alkali iodide and water, preventing hydrogen iodide condensation and the associated corrosion problems while maintaining effective acetic acid purification

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful hydrogen iodide that causes corrosion is converted into beneficial products through reaction with the alkali component. The hydrogen iodide is transformed into alkali iodide (a harmless byproduct) and water, turning a corrosive hazard into a manageable chemical reaction that protects the distillation system

Inventive Principle:

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

2Quantity of substance

If hydrogen iodide concentration is reduced by adjusting water concentration based on equilibrium theory, then some condensation is prevented, but the concentration of hydrogen iodide cannot be decreased at a high level and condensation in the second distillation column cannot be inhibited

Engineering Contradiction:

Improvehydrogen iodide concentrationVSAvoidcondensation inhibition effectiveness

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

Instead of relying solely on water concentration adjustment, the invention changes the chemical parameter by introducing an alkali component that chemically reacts with hydrogen iodide. This fundamental parameter change (from physical equilibrium adjustment to chemical neutralization) enables high-level decrease in hydrogen iodide concentration and reliable prevention of condensation in both first and second distillation columns

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If expensive corrosion-resistant materials are used for the distillation column, then corrosion from hydrogen iodide condensation is prevented, but production costs increase

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidproduction cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The invention converts the harmful corrosive environment into a controlled chemical reaction zone by adding alkali component. This transforms the need for expensive corrosion-resistant materials into a chemical protection strategy, allowing the use of ordinary, cost-effective materials while maintaining system integrity through the neutralization reaction

Inventive Principle:

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

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 significantly inhibits hydrogen iodide condensation throughout the second distillation column, reducing corrosion and allowing for efficient production of high-quality acetic acid while enabling the use of less expensive, lower-grade materials for the distillation column, thus lowering production costs.

Implementation Method 1

the alkali component is added to crude acetic acid... effectively neutralizes hydrogen iodide, preventing its condensation

Methodology Applied

Scientific EffectNeutralization reaction: Chemical Bonding

Implementation Method 2

subjecting the stream containing acetic acid to a second distillation column to remove water and others and separate an acetic acid stream as a liquid stream

Methodology Applied

Scientific EffectDistillation: Distillation

Data Source

PatentUS9776944B2Process for producing acetic acid

Publication Date: 2017.10.03 DAICEL CORP

AI summary

A process for producing acetic acid including an acetic acid collection step for feeding a first distillation column with a volatile component at least containing acetic acid, methyl acetate, methyl iodide, water, and hydrogen iodide. Separating a first lower boiling point component as an overhead, and collecting a first liquid stream containing acetic acid. An acetic acid purification step for feeding a second distillation column with the first liquid stream, and separating a second lower boiling point component as an overhead. Collecting a second liquid stream containing acetic acid. An alkali component is added or mixed for distilling a mixture to be treated containing the first liquid stream and the alkali component in the second distillation column. In the mixture, at least one component (A) having a boiling point lower than acetic acid. The at least one component (A) having a concentration of 0.1 to 15% by weight.