Multimodal Silica Catalyst Structure for High-Selectivity Acrylate Synthesis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalysts for producing ethylenically unsaturated carboxylic acids or esters, such as acrylic acids or alkyl acrylates, suffer from low selectivity and high formation of heavies during the condensation of carboxylic acids or esters with formaldehyde, particularly when higher loadings of catalytic metal are used.
Innovation Solution
A catalyst comprising a multimodal silica support with a mesoporous and macroporous pore size distribution, modified by a modifier metal and containing a catalytic alkali metal, such as caesium, is used to enhance selectivity and reduce heavy by-product formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher loadings of catalytic metal are used, then productivity is improved, but selectivity deteriorates and heavy by-product formation increases
Solution Approach 1:
The catalyst support is segmented into multiple pore size modes (micropores, mesopores, and macropores) to create distinct functional zones. Micropores provide high surface area for catalysis, mesopores facilitate mass transport, and macropores prevent heavy by-product formation. This segmentation allows the catalyst to maintain high productivity while improving selectivity even at higher metal loadings.
Solution Approach 2:
Different regions of the catalyst support are assigned different pore sizes and functional characteristics. The local quality varies throughout the support structure, with specific zones optimized for catalysis, mass transport, and by-product prevention. This local differentiation enables the catalyst to achieve both high reaction rate and high selectivity simultaneously.
2Ease of manufacture
If conventional silica support is used, then ease of manufacture is maintained, but selectivity deteriorates and heavy formation increases
Solution Approach 1:
The silica support is designed as a composite material incorporating multiple pore size modes (microporous, mesoporous, and macroporous structures). This composite architecture combines the ease of manufacturing conventional silica with enhanced selectivity properties, achieving both simplicity in preparation and high performance in catalysis.
3Device complexity
If conventional catalyst structure is used, then device complexity is low, but formation of heavies is high
Solution Approach 1:
The catalyst structure is segmented into multiple pore size categories, with macropores specifically designed to prevent heavy by-product formation. This segmentation adds structural complexity but effectively reduces harmful heavy formation while maintaining reasonable ease of manufacture through established silica preparation methods.
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 catalyst achieves high selectivity and low formation of heavies during the production of ethylenically unsaturated carboxylic acids or esters, even at higher catalytic metal loadings, by maintaining an open pore structure and reducing unwanted coupling reactions.
Implementation Method 1
a multimodal silica support with a mesoporous and macroporous pore size distribution... maintaining an open pore structure
Implementation Method 2
a catalytic alkali metal... by the condensation of carboxylic acid or esters with formaldehyde in the presence of such catalysts
Data Source
AI summary
The invention discloses a catalyst comprising a silica support, a modifier metal and a catalytic alkali metal. The silica support has a multimodal pore size distribution comprising a mesoporous pore size distribution having an average pore size in the range 2 to 50 nm and a pore volume of said mesopores of at least 0.1 cm3/g, and a macroporous pore size distribution having an average pore size of more than 50 nm and a pore volume of said macropores of at least 0.1 cm3/g. The level of catalytic alkali metal on the silica support is at least 2 mol %. The modifier metal is selected from Mg, B, Al, Ti, Zr and Hf. The invention also discloses a method of producing the catalyst, a method of producing an ethylenically unsaturated carboxylic acid or ester in the presence of the catalyst, and a process for preparing an ethylenically unsaturated acid or ester in the presence of the catalyst.