Modified Silica Catalyst for Ethylenic Acid Production
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalysts for producing ethylenically unsaturated carboxylic acids or esters, such as acrylic acids or esters, face challenges in selectivity and catalyst surface sintering during the condensation reaction with methylene sources like formaldehyde, leading to reduced surface area and catalyst lifespan.
Innovation Solution
A modified silica catalyst is developed by incorporating a modifier metal, such as zirconium or hafnium, in mono- or dinuclear moieties on an uncalcined silica support, followed by adsorption and calcination with a catalytic metal like caesium, which enhances selectivity and resistance to sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catalysts are used for the condensation reaction, then the production of ethylenically unsaturated carboxylic acids or esters can be achieved, but the selectivity is poor and catalyst surface sintering occurs leading to reduced surface area and catalyst lifespan
Solution Approach 1:
The catalyst employs different metals with specific functions distributed across the catalyst structure: modifier metals (Zr, Hf, Ti, Al) in mono- or dinuclear moieties provide structural stability and resistance to sintering, while catalytic metals (Cs, K, Rb) provide the active sites for the condensation reaction. This local differentiation of functions resolves the contradiction by ensuring both high selectivity (through optimized catalytic sites) and long lifespan (through sintering-resistant structure).
Solution Approach 2:
The catalyst is a composite material combining multiple metals (modifier metals + catalytic metals) on a silica support. This composite structure allows the modifier metals to prevent sintering while the catalytic metals maintain high selectivity for the condensation reaction, thereby simultaneously improving reliability and manufacturing precision.
2Productivity
If the catalyst is used at elevated temperatures (250-400°C) for the condensation reaction, then the reaction proceeds efficiently, but catalyst surface sintering accelerates leading to loss of surface area
Solution Approach 1:
The modifier metals (Zr, Hf, Ti, Al) are incorporated into the catalyst structure in advance, forming mono- or dinuclear moieties that act as structural anchors. This preliminary incorporation creates a sintering-resistant framework before the catalyst is deployed at high temperatures, allowing the catalyst to maintain its surface area throughout the reaction process while operating efficiently at 250-400°C.
Solution Approach 2:
The invention changes the structural parameters of the catalyst by incorporating modifier metals in specific oxidation states and coordination environments. These parameter changes create a more thermally stable catalyst structure that resists sintering at elevated temperatures, thereby maintaining surface area while enabling high-temperature operation for improved productivity.
3Reliability
If modifier metals are incorporated in high quantities to improve sintering resistance, then catalyst lifespan increases, but the complexity of catalyst preparation and cost increase
Solution Approach 1:
The invention uses modifier metals at relatively low loadings (0.01-0.10 mmol/g) compared to what would be needed if modifier metals were the sole active component. This partial action approach is sufficient to provide structural stabilization and sintering resistance when combined with the catalytic metals, thereby extending catalyst lifespan without proportionally increasing preparation complexity or cost.
Solution Approach 2:
The silica support acts as an intermediary that facilitates the incorporation of modifier metals in controlled quantities. The support provides a large surface area with uniform distribution sites, allowing low levels of modifier metals to be effectively dispersed and utilized for sintering prevention, thus achieving extended lifespan without complex preparation procedures.
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 modified silica catalyst exhibits improved selectivity and reduced sintering, resulting in a higher catalyst surface area and extended lifespan for the production of ethylenically unsaturated carboxylic acids or esters, particularly in the production of methacrylic acid and methyl methacrylate.
Implementation Method 1
treating the silica support with a mono- or dinuclear modifier metal compound so that modifier metal is adsorbed onto the surface of the silica support through reaction with isolated silanol groups
Implementation Method 2
treating the uncalcined modified silica support with a catalytic metal to effect adsorption of the catalytic metal onto the metal modified silica support
Data Source
AI summary
A process for producing a catalyst including a) providing an uncalcined metal modified porous silica support wherein the modifier metal is selected from one or more of boron, magnesium, aluminium, zirconium, hafnium and titanium, wherein the modifier metal is present in mono- or dinuclear modifier metal moieties; b) optionally removing any solvent or liquid carrier from the modified silica support; c) optionally drying the modified silica support; d) treating the uncalcined metal modified silica support with a catalytic metal to effect adsorption of the catalytic metal onto the metal modified silica support; and e) calcining the impregnated silica support of step d). The invention extends to an uncalcined catalyst intermediate and a method of producing a catalyst by providing a porous silica support having isolated silanol groups.