Zeolite Catalyst Isomerization Selectivity for 2,5-Dichlorophenol

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Solution Overview

Problem

Current processes for producing 2,5-dichlorophenol face challenges such as high raw material costs, low process conversions, and high waste generation, with existing zeolite catalysts failing to achieve high selectivity for 2,5-dichlorophenol, leading to inefficient production of dicamba, an important herbicide.

Innovation Solution

The use of a zeolite catalyst with a SiO2/Al2O3 mole ratio of no greater than 35:1, specifically a desilicated zeolite with enhanced meso-macro pore volume, in conjunction with steam rejuvenation, to isomerize 2,4-dichlorophenol and hydroxylate 1,4-dichlorobenzene, improving selectivity and yield of 2,5-dichlorophenol.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional zeolite catalysts are used for isomerization of 2,4-dichlorophenol, then the process can proceed, but the selectivity for 2,5-dichlorophenol is insufficient

Engineering Contradiction:

Improveselectivity for 2,5-dichlorophenolVSAvoidyield of 2,5-dichlorophenol

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent modifies the zeolite catalyst by changing the SiO2/Al2O3 mole ratio parameter to no greater than 35:1, and introduces desilication treatment to enhance meso-macro pore volume. These parameter changes in catalyst composition and structure significantly improve the selectivity for 2,5-dichlorophenol while maintaining productivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the porous structure of zeolite catalysts, specifically enhancing the meso-macro pore volume through desilication. This porous material modification allows improved access to active sites and better selectivity for the desired isomerization product, resolving the contradiction between selectivity and productivity.

Inventive Principle:

Principle #31Porous materials

2Loss of substance

If existing production processes are used, then 2,5-dichlorophenol can be produced, but raw material costs are high and waste generation is large

Engineering Contradiction:

Improvewaste generationVSAvoidprocess conversion

Core Design Contradiction:

Loss of substanceVSProductivity

Solution Approach 1:

By changing the catalyst parameters (SiO2/Al2O3 ratio ≤ 35:1 and desilication treatment), the process achieves higher conversion efficiency and reduces waste generation. The improved catalyst facilitates more efficient isomerization, reducing the need for additional raw materials and minimizing byproducts.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of low selectivity (which causes waste) into a benefit by using desilicated zeolite catalysts that achieve high selectivity. This transforms the previous waste-generating process into a high-efficiency process with minimal waste, addressing both loss of substance and productivity concerns.

Inventive Principle:

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

3Productivity

If 2,4-dichlorophenol is isomerized using conventional catalysts, then some conversion occurs, but the process conversion is low

Engineering Contradiction:

Improveprocess conversionVSAvoidselectivity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes to the catalyst (SiO2/Al2O3 ≤ 35:1 and desilication) that simultaneously improve both process conversion and selectivity. The modified catalyst structure provides more active sites and better pore accessibility, enabling higher conversion while maintaining high selectivity for 2,5-dichlorophenol.

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 approach significantly enhances the selectivity and yield of 2,5-dichlorophenol, reducing waste and raw material costs, thereby improving the economic viability of dicamba production.

Implementation Method 1

contacting a feed gas or a liquid comprising 2,4-dichlorophenol with a zeolite catalyst in acid form in an isomerization zone to isomerize at least a portion of the 2,4-dichlorophenol to 2,5-dichlorophenol

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

isomerize at least a portion of the 2,4-dichlorophenol to 2,5-dichlorophenol

Methodology Applied

Scientific EffectIsomerization:

Implementation Method 3

hydroxylating 1,4-dichlorobenzene with an oxidizing agent in the presence of a first zeolite catalyst in a hydroxylation zone to form a hydroxylation reaction product comprising 2,5-dichlorophenol and 2,4-dichlorophenol

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS11008276B2Processes for preparing 2,5-dichlorophenol

Publication Date: 2021.05.18 GHARDA CHEMICALS INTERNATIONAL INC

AI summary

Processes for producing 2,5-dichlorophenol and 3,6-dichloro-2-methoxybenzoic acid are described. Various processes for isomerizing 2,4-dichlorophenol over a zeolite catalyst to form 2,5-dichlorophenol are provided. Processes for preparing 2,5-dichlorophenol including hydroxylating 1,4-dichlorobenzene are also described. The present invention also relates to processes for producing 3,6-dichloro-2-methoxybenzoic acid.