Saddle-Shaped Oxidation Catalyst Preventing Coke Clogging
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Solution Overview
Problem
Existing oxidation catalysts face challenges in maintaining high selectivity and low pressure drop during the oxidation of (meth)acrolein to (meth)acrylic acid, o-xylene to phthalic anhydride, or alkenes to alkadienes, as they tend to clog with coke residues and experience increased pressure drop over time.
Innovation Solution
An oxidation catalyst with a nonporous, inorganic, ceramic support body having a BET surface area of less than 0.5 m2/g, coated with a catalytically active multielement oxide, featuring a saddle-shaped structure to minimize clogging and pressure loss, and utilizing a binder for coating to enhance adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If porous catalyst supports are used to provide surface area for catalytic activity, then catalytic activity is improved, but pressure drop increases and clogging with coke residues occurs over time
Solution Approach 1:
The patent applies porous materials by using a porous eggshell coating on the outer surface of the support body. This porous coating provides the necessary surface area for catalytic activity while the overall structure maintains low pressure drop. The porosity is controlled to balance catalytic performance with resistance to coke clogging.
Solution Approach 2:
The patent uses composite materials by combining a nonporous support body (made from materials like alumina, silica, or steatite) with a porous eggshell coating containing catalytically active oxide. This composite structure allows the support body to maintain structural integrity and low pressure drop while the coating provides catalytic functionality.
2Productivity
If catalyst supports with high surface area are used to increase catalytic activity, then reaction efficiency is improved, but selectivity decreases due to coke accumulation
Solution Approach 1:
The patent applies local quality by concentrating the catalytically active material specifically in the eggshell coating layer on the outer surface, rather than throughout the entire support body. This localized catalytic activity provides high reaction efficiency at the active sites while the nonporous support structure prevents coke accumulation that would otherwise reduce selectivity over time.
3Productivity
If conventional catalyst structures are used, then initial performance is achieved, but pressure drop increases during operation due to clogging
Solution Approach 1:
The patent inverts the conventional approach by making the support body nonporous (rather than porous) and placing the porous catalytic coating only on the outer surface. This inversion of the traditional porous support structure prevents coke penetration into the support body, maintaining low pressure drop throughout the operational life while still providing sufficient catalytic activity through the outer coating.
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 improved selectivity and maintains low pressure drop throughout its operational life by preventing coke residue accumulation and ensuring efficient gas phase oxidation reactions.
Implementation Method 1
the catalyst being precious metal-free and the shaped support body having the form of a saddle whose saddle surface is curved oppositely in the two principal directions
Implementation Method 2
oxidation catalyst, to a process for producing it, to its use in various catalytic gas phase oxidations
Data Source
AI summary
The invention relates to an oxidation catalyst comprising at least one inorganic, oxidic or ceramic, shaped support body having a BET surface area of less than 0.5 m2/g, based on the support, which is at least partly coated with a catalytically active multielement oxide, the catalyst being precious metal-free and the shaped support body having the form of a saddle whose saddle surface is curved oppositely in the two principal directions, to a process for producing it, to its use in various catalytic gas phase oxidations, and to corresponding processes for catalytic gas phase oxidation.