Gold Catalyst Physical Vapor Deposition Process
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Solution Overview
Problem
The challenge lies in developing gold-based catalyst systems that maintain nanoscale gold particles' catalytic activity while avoiding coalescence, which is difficult due to gold's high mobility and the limitations of existing deposition methods like coprecipitation and deposition-precipitation, leading to reproducibility issues and reduced catalytic performance.
Innovation Solution
The process involves depositing fine-nanoscale gold onto nanoparticulate support media using physical vapor deposition in an oxidizing atmosphere, such as oxygen, water, or ozone, which enhances catalytic activity and prevents coalescence, allowing for effective catalysis of oxidation processes like carbon monoxide oxidation with reduced gold loading and without the need for thermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If coprecipitation or deposition-precipitation methods are used to deposit gold on support, then gold can be deposited on the support, but gold particles coalesce and lose catalytic activity
Solution Approach 1:
The patent replaces chemical deposition mechanisms (coprecipitation, deposition-precipitation) with physical vapor deposition. This substitution eliminates the need for chemical reactions that cause gold particle coalescence, allowing gold to be deposited in a controlled manner that maintains nanoparticle integrity and catalytic activity.
Solution Approach 2:
The patent changes the deposition parameters by using physical vapor deposition at controlled temperatures and pressures. By depositing gold in a vacuum or controlled atmosphere and then performing mild thermal treatment, the gold particles are deposited as fine nanoparticles that do not coalesce, maintaining their catalytic activity.
2Reliability
If thermal treatment is applied to activate gold catalyst, then catalyst activation is achieved, but gold particles coalesce and catalytic sites are inactivated
Solution Approach 1:
The patent performs preliminary action by depositing gold as fine nanoparticles through physical vapor deposition before any thermal treatment. This preliminary deposition creates a stable nanoparticle structure that is resistant to coalescence during subsequent mild thermal treatment, enabling activation without loss of particle size control.
Solution Approach 2:
The patent changes the thermal treatment parameters from high-temperature activation to mild thermal treatment at lower temperatures. This parameter change allows sufficient catalyst activation while preventing gold particle coalescence and maintaining the fine nanoparticle structure necessary for catalytic activity.
3Quantity of substance
If aqueous base is added to hydrolyze gold solutions, then gold precipitation occurs, but reproducibility is poor due to inhomogeneous hydrolysis
Solution Approach 1:
The patent replaces the chemical hydrolysis process (adding aqueous base) with physical vapor deposition. This substitution eliminates the inhomogeneous hydrolysis problem entirely, as gold is deposited directly from the vapor phase onto the support surface in a controlled and uniform manner, ensuring high reproducibility.
4Loss of substance
If gold loading is reduced to lower cost, then cost-effectiveness improves, but catalytic activity may be insufficient
Solution Approach 1:
The patent uses physical vapor deposition to achieve ultra-dispersed gold nanoparticles on the support surface. This method maximizes the surface area coverage and dispersion of gold, ensuring that even at low loadings, the gold particles are optimally distributed and highly active, maintaining catalytic performance while reducing gold consumption.
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 produces robust, consistent, and uniform gold-based catalyst systems that exhibit enhanced catalytic activity over a wide temperature range, including room temperature, with reduced gold usage, making them cost-effective for applications like carbon monoxide abatement and diesel exhaust treatment.
Implementation Method 1
depositing fine-nanoscale gold onto a nanoparticulate support medium by physical vapor deposition in an oxidizing atmosphere
Implementation Method 2
carrying out physical vapor deposition of fine-nanoscale gold (for example, by sputtering) on nanoparticulate substrates in an oxidizing atmosphere
Data Source
AI summary
A process for producing gold-based, heterogeneous catalyst systems comprises depositing fine-nanoscale gold onto a nanoparticulate support medium by physical vapor deposition in an oxidizing atmosphere.