Titanium-Modified Silica Catalyst for Selective Acid Production
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Solution Overview
Problem
Existing catalysts for the production of ethylenically unsaturated carboxylic acids or esters, such as acrylic acids or esters, suffer from low selectivity and rapid catalyst surface sintering during the condensation reaction with methylene sources like formaldehyde.
Innovation Solution
The use of a modified silica catalyst support modified with titanium metal, where at least 25% of the modifier metal is present as mononuclear titanium species, enhances the binding of catalytic metals and improves selectivity and activity in the production of unsaturated carboxylic acids or esters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional silica supports are used, then catalyst activity is maintained, but selectivity is low and catalyst surface sintering occurs rapidly
Solution Approach 1:
The invention changes the chemical and structural parameters of the silica support by incorporating mononuclear titanium species at specific concentrations (0.1-5 wt%). This modification alters the surface properties of the support, creating specific active sites that enhance selectivity for the desired condensation reaction while simultaneously reducing the rate of surface sintering that normally occurs at elevated reaction temperatures (250-400°C).
Solution Approach 2:
The invention creates a composite catalyst system by combining modified silica support containing mononuclear titanium species with catalytic metal components (such as alkali or alkaline earth metals). This composite structure synergistically improves both selectivity and catalyst stability, where the titanium-modified silica provides selective active sites while the catalytic metal enhances reaction activity, and the overall composite resists sintering better than conventional supports.
2Productivity
If catalyst surface area is increased to improve activity, then reaction rate increases, but surface sintering accelerates
Solution Approach 1:
The invention modifies the thermal and structural stability parameters of the catalyst surface by incorporating mononuclear titanium species. These modified surfaces maintain high surface area and resist sintering at elevated temperatures, enabling the catalyst to sustain high reaction rates over extended periods without the usual degradation of surface properties that would normally limit productivity.
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 results in higher selectivity and reduced catalyst surface sintering, leading to improved reaction performance and extended catalyst life during the production of ethylenically unsaturated carboxylic acids or esters.
Implementation Method 1
at least a proportion of the modifier metal is incorporated or present in the support in the form of mononuclear titanium species
Data Source
AI summary
A catalyst including a modified silica support having a titanium modifier metal, and a catalytic metal on the modified silica support. A proportion of the modifier metal is present in the form of mononuclear titanium moieties or is derived from a mononuclear titanium cation source at the commencement of modification. The invention also discloses a corresponding modified silica support, a method of producing the catalyst or the modified silica support, and a process for preparing an ethylenically unsaturated acid or ester in the presence of the catalyst.