Metal Oxide Catalyst Synthesis via Supercritical CO2 Extraction
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Solution Overview
Problem
Existing methods for synthesizing metal oxide catalysts using porous supports with low chemical/physical stability often damage the support structure and active sites during solvent removal, leading to reduced catalyst performance in heterogeneous catalytic reactions.
Innovation Solution
The use of supercritical carbon dioxide (CO2) extraction to remove synthetic solvents from metal oxide catalysts, which minimizes damage to the support and active sites by leveraging its low viscosity, high diffusivity, and weak interaction with the solid, allowing for controlled synthesis of catalysts with optimized surface properties and redox properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional methods (filtration, washing, or thermal drying) are used to remove synthetic solvent, then solvent removal is achieved, but the support structure and active sites are damaged or collapsed
Solution Approach 1:
The patent changes the physical parameters of the extraction fluid by using supercritical CO2 instead of conventional solvents. The supercritical state is achieved by adjusting temperature and pressure parameters, allowing the fluid to have both gas-like diffusivity and liquid-like density, enabling effective solvent removal without the capillary damage caused by conventional liquid solvents
Solution Approach 2:
Supercritical CO2 acts as an intermediary extraction fluid between the synthetic solvent and the catalyst support. It selectively extracts the synthetic solvent through weak intermolecular forces while avoiding the strong capillary effects that would damage the support structure, thus mediating the removal process safely
2Stability of the object's composition
If synthetic solvent is used for dispersion of active site precursors, then active sites are dispersed, but strong interaction between solvent and support causes damage during removal
Solution Approach 1:
The patent converts the harmful strong interaction between synthetic solvent and support into a beneficial selective extraction process. By using supercritical CO2, the weak interaction allows the solvent to be extracted without causing capillary damage, transforming the extraction process from harmful to beneficial
3Reliability
If supercritical CO2 extraction is used to remove solvent, then support structure is protected, but the process requires specific temperature and pressure conditions
Solution Approach 1:
The patent employs parameter changes by adjusting temperature and pressure to achieve the supercritical state of CO2. These parameter adjustments enable the extraction process to proceed under controlled conditions that protect the support structure while maintaining process feasibility
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 method enhances the rate, conversion, and selectivity of catalytic reactions involving N—O, N—H, C—O, and O—H bonds, improving the performance and durability of metal oxide catalysts in reactions such as SCR and SCO by maintaining the structural integrity of the catalysts and optimizing the distribution of acid sites and oxygen species.
Implementation Method 1
drying a catalyst crystalline grain precursor-support intermediate product using supercritical CO2 extraction
Implementation Method 2
A supercritical CO2 fluid may provide characteristics of 1) small viscosity, 2) high diffusivity into miscibility with solvents with various polarities, and 3) weak interaction with solid support/active sites
Implementation Method 3
high diffusivity into miscibility with solvents with various polarities
Implementation Method 4
the capillary effect in which the synthetic solvent strongly attracts the support/active sites during removal from support pores
Data Source
AI summary
A metal oxide catalyst synthesized using supercritical carbon dioxide extraction is provided, wherein the metal oxide catalyst includes an active site containing at least one type of metal oxide and a support for loading the active site and the metal oxide is an oxide of a metal selected from the group consisting of transition metals (atomic number 21 to 29, 39 to 47, 72 to 79, or 104 to 108), lanthanide (atomic number 57 to 71), post-transition metals (atomic number 13, 30 to 31, 48 to 50, 80 to 84, and 112), and metalloids (atomic number 14, 32 to 33, 51 to 52, and 85) in the periodic table, and a combination thereof.