Tungsten-Molybdenum Catalyst Preparation for Selective Oxidation
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Solution Overview
Problem
Conventional catalysts for the partial oxidation of methylbenzenes to produce aromatic aldehydes suffer from low selectivity and yield, making industrial application challenging due to by-product issues, complex composition, and short heat stability, limiting their practicality and scalability.
Innovation Solution
A novel catalyst preparation method involving tungsten oxide supported on a fire-resistant inorganic carrier, with a specific pore volume ratio, and repetitive supporting and drying steps to enhance selectivity and stability, allowing for high selectivity and yield of aromatic aldehydes through gas-phase oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional complex oxide catalysts (multi-component) are used, then conversion rate of p-xylene is improved, but selectivity and yield of terephthalaldehyde deteriorate due to various by-products
Solution Approach 1:
The patent extracts and eliminates the Sb component from the catalyst composition, retaining only W and Mo components. This extraction resolves the contradiction by removing the source of low selectivity and heat stability issues while preserving the high conversion rate capability, achieving both high productivity and high selectivity simultaneously
Solution Approach 2:
The patent optimizes the ratio parameters of W and Mo components in the catalyst, specifically setting W:Mo ratio within 1:1 to 20:1. This parameter optimization resolves the contradiction by finding the optimal balance point where both conversion rate and selectivity are maximized, eliminating the need for Sb component
2Productivity
If conventional catalysts with low selectivity are used, then yield of terephthalaldehyde is improved, but separation and purification of by-products becomes difficult
Solution Approach 1:
The patent removes the Sb component that causes low selectivity, thereby eliminating the by-product formation issue. This extraction simplifies the separation and purification process while maintaining high yield, as the catalyst now produces minimal by-products that require no complex separation
3Productivity
If catalysts comprising Sb component are used, then high yield of terephthalaldehyde is achieved, but heat stability and life span deteriorate due to sublimation and loss at high temperature
Solution Approach 1:
The patent extracts and removes the Sb component from the catalyst composition, eliminating the sublimation and loss problem at high temperatures. This extraction maintains high yield capability while significantly improving heat stability and catalyst life span, as W and Mo components remain stable at reaction temperatures
Solution Approach 2:
The patent replaces the unstable Sb component with stable W and Mo components that maintain their structural integrity at high temperatures. This substitution eliminates the need for frequent catalyst replacement while maintaining high productivity
4Productivity
If multi-component complex oxide catalysts are used, then conversion rate is improved, but ease of preparation and homogeneity of composition deteriorates
Solution Approach 1:
The patent removes the Sb component, simplifying the catalyst composition to binary W-Mo system. This extraction greatly eases the preparation process and improves compositional homogeneity, as fewer components mean simpler mixing and more uniform distribution, while maintaining high conversion rate
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
The method achieves high selectivity and yield of aromatic aldehydes, maintaining uniform selectivity over a wide range of conversion rates, improving the catalyst's industrial practicality and reducing by-product complexity.
Implementation Method 1
a catalyst for partial oxidation of methylbenzenes... gas phase oxidation of methylbenzenes with oxygen
Implementation Method 2
supporting the solution or slurry obtained in the step (a) on inorganic carrier
Implementation Method 3
the ratio of the pore volume of inorganic carrier and the volume of the solution or slurry in the step (b) is 1:0.9 ̃1.1
Data Source
AI summary
The present invention relates to a novel method for preparing a catalyst for partial oxidation of methylbenzenes, comprising, (a) a step of preparing a solution or slurry of the compounds comprising tungsten; (b) a step of supporting the solution or slurry obtained in the step (a) on inorganic carrier; (c) a step of drying the catalyst obtained in the step (b); and (d) a step of calcining the dried catalyst obtained in the step (c), characterized in that the ratio of the pore volume of inorganic carrier and the volume of the solution or slurry in the step (b) is 1:0.9˜1.1, and the catalyst provides superior aromatic aldehydes selectivity to those prepared by the conventional impregnation or heat evaporation method over a wide range of conversion rate.