Gold Catalyst Oxidation of Methacrolein to Methacrylic Acid
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Solution Overview
Problem
Current methods for liquid-phase oxidation of methacrolein to produce methacrylic acid are inefficient and require optimization to achieve higher selectivity and yield, as existing processes often require harsh conditions and larger equipment.
Innovation Solution
A method involving a heterogeneous catalyst with gold supported on oxides such as γ-, δ-, or θ-alumina, titania, or ceria, where the gold is predominantly located in the outer volume of the catalyst particles, is used to contact a liquid mixture of methacrolein and water with oxygen, optimizing reaction conditions like water concentration and solvent choice to enhance methacrylic acid production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid-phase oxidation is used instead of gas-phase oxidation, then milder conditions and smaller equipment are expected, but existing liquid-phase processes require harsh conditions and larger equipment
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by introducing a specific aqueous-organic solvent mixture (acetonitrile-water or diglyme-water) and controlling water concentration above 25%, which enables the reaction to proceed under milder conditions with improved selectivity and yield, resolving the contradiction between mild conditions and equipment requirements
Solution Approach 2:
The patent employs a composite catalyst system consisting of gold nanoparticles supported on metal oxides (such as TiO2, CeO2, Al2O3), combining the catalytic activity of gold with the support properties of metal oxides to achieve high selectivity and activity under milder conditions, thereby eliminating the need for harsh conditions and large equipment
2Productivity
If existing liquid-phase oxidation processes are used, then methacrylic acid can be produced, but selectivity and yield are low and require optimization
Solution Approach 1:
The patent optimizes reaction parameters including water concentration (above 25%), temperature (60-80°C), and solvent composition (acetonitrile-water or diglyme-water mixtures), which simultaneously improves both selectivity (surpassing 90%) and yield of methacrylic acid
Solution Approach 2:
The patent creates a specific local chemical environment around the gold catalyst particles by using aqueous-organic solvent mixtures, where the water concentration above 25% creates favorable local conditions for selective oxidation, achieving high selectivity and yield simultaneously
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 achieves high selectivity and yield of methacrylic acid, with selectivity surpassing 90% and space-time yield maximization when water concentration is above 25%, and demonstrates the importance of the catalyst support and solvent choice in the reaction efficiency.
Implementation Method 1
contacting a liquid mixture comprising methacrolein and water in the presence of oxygen with a heterogeneous catalyst comprising a support and gold
Implementation Method 2
liquid-phase oxidation of methacrolein to produce methacrylic acid
Data Source
AI summary
A method for preparing methacrylic acid from methacrolein. The method comprises contacting a liquid mixture comprising methacrolein and water in the presence of oxygen with a heterogeneous catalyst comprising a support and gold; wherein the support comprises an oxide selected from γ-, δ-, or θ-alumina, magnesia, titania, zirconia, hafnia, vanadia, niobium oxide, tantalum oxide, ceria, yttria, lanthanum oxide, zinc oxide or a combination thereof.