Ozone-Activated Nanoporous Gold Catalyst Selectivity
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Solution Overview
Problem
Nanoporous gold catalysts face challenges in reproducible activation and maintaining activity for selective oxidation processes, particularly due to agglomeration and inconsistent activation methods, which hinder their use in large-scale chemical transformations.
Innovation Solution
A method involving ozone treatment at elevated temperatures to activate nanoporous gold catalysts, ensuring consistent and reproducible activation, and maintaining activity for selective oxidation of alcohols while being inactive for CO oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanoporous gold catalysts are activated using conventional methods (flowing reactant gases at moderate temperatures), then the catalyst may become active for CO oxidation, but the activation process is highly inconsistent and irreproducible, with some materials activating easily while others do not activate at all
Solution Approach 1:
The patent changes the activation parameters by using ozone instead of conventional reactant gas flows, and by conducting activation at elevated temperatures (100-200°C) rather than moderate temperatures. This parameter change achieves reproducible activation across different nanoporous gold materials while maintaining selectivity for alcohol oxidation over CO oxidation
Solution Approach 2:
The patent employs ozone, a strong oxidant, as the activation agent. Ozone treatment at elevated temperatures effectively activates the nanoporous gold catalysts by creating the necessary surface oxygen species, providing consistent and reproducible activation that conventional methods cannot achieve
2Reliability
If nanoporous gold catalysts are activated for methanol self-coupling using conventional methods, then the catalyst becomes active for that reaction, but the catalyst deactivates after exposure to higher alcohols such as ethanol and 1-butanol
Solution Approach 1:
The patent changes the activation conditions to elevated temperatures (100-200°C) with ozone treatment, which creates a more stable and versatile catalyst surface that can handle multiple substrate types including both methanol and higher alcohols without deactivation, thereby expanding substrate scope while maintaining stability
Solution Approach 2:
The ozone-activated nanoporous gold catalyst achieves multi-functionality by being able to catalyze the oxidation of various alcohol substrates (methanol, ethanol, 1-butanol, etc.) with consistent performance. The activation method creates a universal catalyst that is not limited to a single substrate type
3Reliability
If nanoporous gold catalysts are used for selective oxidation, then high selectivity for desired products can be achieved, but the catalysts have a propensity to agglomerate and rapidly lose activity
Solution Approach 1:
The patent changes the activation temperature parameter to elevated ranges (100-200°C) which appears to stabilize the nanoporous gold structure, preventing agglomeration and maintaining both selectivity and longevity during catalytic operation
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 ozone-activated nanoporous gold catalysts demonstrate stable and selective catalytic activity for the oxidation of alcohols, producing esters and aldehydes with high selectivity and longevity, overcoming previous issues of agglomeration and inconsistent activation.
Implementation Method 1
The 1-3% Ag that remains in the material after this particular etching procedure is key to the activity of nanoporous gold for oxidative catalysis. The residual Ag dissociates molecular oxygen (O2) to form adsorbed O
Implementation Method 2
The residual Ag dissociates molecular oxygen (O2) to form adsorbed O
Implementation Method 3
Nanoscale gold supported on metal oxides has been widely investigated as a catalyst material for selective oxidation
Implementation Method 4
The ozone-activated nanoporous gold catalysts demonstrate stable and selective catalytic activity for the oxidation of alcohols, producing esters and aldehydes with high selectivity
Data Source
AI summary
The invention relates to nanoporous gold nanoparticle catalysts formed by exposure of nanoporous gold to ozone at elevated temperatures, as well as methods for production of esters and other compounds.