Halogen-Free Catalyst for Toluene Oxidation
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Solution Overview
Problem
The existing methods for oxidizing toluene to benzoic acid in benzoic acid solvent are hindered by the slow oxidation rate when using a cobalt-catalyzed system without a halide promoter, making it impractical for industrial use, and the corrosive nature of bromide promoters restricts reactor material choice to expensive alloys.
Innovation Solution
A catalyst system comprising a cobalt compound, a zirconium or hafnium compound, and an alkali metal basic salt, with a molar ratio of alkali metal to cobalt ranging from 0.1:1 to 1:1, operates in the absence of a halogen promoter, enhancing the oxidation rate of toluene to benzoic acid in benzoic acid solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a cobalt-catalyzed oxidation system is used in benzoic acid solvent without a halide promoter, then the corrosion problem is eliminated and cheaper reactor materials can be used, but the oxidation rate becomes too slow for practical use
Solution Approach 1:
The invention changes the chemical composition parameters of the catalyst system by introducing zirconium or hafnium compounds alongside cobalt, and specifically adds an alkali metal basic salt (such as sodium benzoate) to the system. This parameter change transforms the catalyst's ability to promote oxidation without requiring corrosive halide promoters, thereby maintaining high oxidation rates while eliminating corrosion issues.
Solution Approach 2:
The invention creates a composite catalyst system combining cobalt compound, zirconium or hafnium compound, and alkali metal basic salt. This composite catalyst achieves synergistic effects where the combination of these components enables high oxidation activity without the need for corrosive bromide promoters, resolving the contradiction between productivity and corrosion resistance.
2Productivity
If a bromide promoter is added to enhance the oxidation rate, then the productivity increases, but the reactor material cost increases due to corrosion requirements
Solution Approach 1:
The invention extracts and eliminates the bromide promoter component from the catalyst system. By removing this corrosive element while retaining and enhancing oxidation capability through the cobalt-zirconium/hafnium-alkali metal basic salt combination, the system achieves high productivity without the need for expensive corrosion-resistant reactor materials.
Solution Approach 2:
The invention replaces expensive, corrosion-resistant reactor materials (such as titanium or nickel alloys) with cheaper, general-purpose materials (such as 304-stainless steel or carbon steel). The new catalyst system enables the use of these less durable but more economical materials by eliminating the corrosive bromide promoter while maintaining high oxidation rates.
3Object-affected harmful factors
If acetic acid is used as solvent instead of benzoic acid, then the corrosion problem is reduced, but the product purification process becomes more complex
Solution Approach 1:
The invention maintains the advantageous properties of benzoic acid solvent (facilitating product purification) while eliminating its disadvantage (corrosion) by replacing the corrosive bromide promoter with a non-corrosive catalyst system comprising cobalt compound, zirconium or hafnium compound, and alkali metal basic salt. This allows the system to 'copy' the beneficial purification characteristics of benzoic acid solvent without inheriting its corrosion problem.
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 catalyst system achieves a high rate of toluene conversion to benzoic acid, allowing for practical industrial application without the need for expensive reactor materials and halogen promoters, enabling efficient production and cost-effective manufacturing.
Implementation Method 1
The oxidation is typically carried out in benzoic acid solvent and is catalyzed by a Co/Mn/Br catalyst system... The present invention provides a catalyst system for oxidizing toluene to benzoic acid in a solvent comprising benzoic acid... comprising: (a) a cobalt compound; (b) a zirconium compound or a hafnium compound or both; and (c) an alkali metal basic salt
Implementation Method 2
The invention generally relates to a catalyst system and method for producing benzoic acid from toluene... oxidizing toluene to benzoic acid... contacting toluene with an oxygen source in the presence of a catalyst system... at conditions effective to produce benzoic acid
Data Source
AI summary
Disclosed is a halide-free catalyst system and method for oxidizing toluene to form benzoic acid in benzoic acid solvent. The catalyst system contains Co, at least one of Zr and Hf, and an alkali metal basic salt.