Cyclohexane Dicarboxylic Acid Isomerization Using Zirconia Catalyst

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Solution Overview

Problem

Current methods for isomerizing cyclohexane dicarboxylic acid (CHDA) to produce high concentrations of trans-cyclohexane dicarboxylic acid (t-CHDA) face challenges such as low t-CHDA purity, difficulty in handling hard t-CHDA, and generation of impurities in thermal isomerization processes.

Innovation Solution

An isomerization method involving heat-treatment of a mixed solution containing CHDA, water, and a transition metal oxide catalyst, specifically zirconia or titania, to efficiently convert cis-cyclohexane dicarboxylic acid to trans-cyclohexane dicarboxylic acid, with controlled catalyst and reaction conditions to achieve high t-CHDA content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If thermal isomerization is performed at high temperature above melting point of t-CHDA, then t-CHDA concentration increases, but t-CHDA becomes very hard and difficult to handle

Engineering Contradiction:

Improvet-CHDA concentrationVSAvoidhandling ease

Core Design Contradiction:

Quantity of substanceVSEase of operation

Solution Approach 1:

The invention changes the reaction parameters by conducting isomerization at moderate temperatures (200-250°C) rather than above the melting point, and by using a catalyst system (alumina modified with phosphoric acid or ammonium phosphosphate) to achieve high t-CHDA concentration without requiring excessive heat, thus resolving the contradiction between concentration and handling ease

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces a catalyst intermediary (alumina modified with phosphoric acid or ammonium phosphosphate) that facilitates the isomerization reaction at lower temperatures, acting as a mediator between the reactants and enabling the transformation without requiring the high temperatures that cause hardness

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If thermal isomerization is performed using alkali metal salt or alkaline earth metal salt, then isomerization reaction proceeds, but impurities of alkali metal or alkaline earth metal are generated

Engineering Contradiction:

Improveisomerization reaction efficiencyVSAvoidimpurity generation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The invention uses alumina as a catalyst support that is chemically stable and does not introduce impurities, replacing alkali metal salts or alkaline earth metal salts that generate harmful impurities. The alumina catalyst can be easily separated and reused, avoiding the contamination issue

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention creates an inert environment by using alumina modified with phosphoric acid or ammonium phosphosphate as the catalyst system, which does not introduce metallic impurities into the reaction system, thereby maintaining product purity while achieving efficient isomerization

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Temperature

If thermal isomerization of aqueous solution is performed at 240°C or higher under pressure, then isomerization reaction occurs, but isomerization proportion to t-CHDA is not high

Engineering Contradiction:

Improvereaction temperatureVSAvoidt-CHDA isomerization proportion

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The invention introduces a catalyst intermediary (alumina modified with phosphoric acid or ammonium phosphosphate) that enables the isomerization reaction to proceed efficiently at moderate temperatures (200-250°C), acting as a mediator that increases the reaction rate without requiring excessive temperature, thus achieving high t-CHDA proportion

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the temperature parameter by conducting the reaction at 200-250°C rather than 240°C or higher, and by introducing a catalyst to lower the activation energy barrier, thereby achieving high isomerization proportion at more moderate temperatures

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 method allows for the efficient production of CHDA with a high trans/cis ratio, achieving t-CHDA content of 50% or more, while minimizing impurities and avoiding the handling issues of hard t-CHDA, with improved reaction efficiency and yield.

Implementation Method 1

heat-treating a mixed solution which is prepared by mixing CHDA including the cis isomer, water, and an isomerization catalyst, wherein the isomerization catalyst includes one or more of oxide of a transition metal of Group 4

Methodology Applied

Scientific EffectCatalysis: Catalysis