Doped Atomic Monolayer Catalysts for Methane Oxidation
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Solution Overview
Problem
Current catalysts for direct methane to methanol (MTM) and preferential oxidation of carbon monoxide (PROX) reactions lack high activity and selectivity, with existing catalysts requiring pre-oxidation, suffering from overoxidation at high temperatures, and being inefficient in the presence of water.
Innovation Solution
Development of catalysts featuring a doped atomic monolayer, such as graphene or hexagonal boron nitride, with a nickel-based component that utilizes electronic atomic monolayer-metal support interaction (EAMSI) to control the activation of small molecules like oxygen, enabling efficient oxidation reactions at low temperatures and preventing overoxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reaction temperature is increased to improve reaction rate, then productivity increases, but overoxidation occurs and selectivity deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of catalyst structure from conventional bulk or nanoparticle metals to two-dimensional monolayer metals supported on oxide surfaces. This structural parameter change enables high reaction rates at low temperatures (below 500K) by providing unique electronic properties and coordination environments that lower activation barriers without requiring high temperatures, thus avoiding overoxidation and maintaining high selectivity.
Solution Approach 2:
The patent creates composite catalyst systems consisting of monolayer metal atoms dispersed on oxide support surfaces (e.g., TiO2, CeO2, Al2O3). This composite structure combines the high activity of metallic sites with the stability and selectivity-modulating properties of oxide supports, enabling simultaneous achievement of high productivity and selectivity through synergistic interactions between the metal monolayer and oxide support.
2Productivity
If conventional metal catalysts are used to achieve high activity, then productivity increases, but the catalysts require pre-oxidation and suffer from low stability
Solution Approach 1:
The patent changes the oxidation state parameter of the catalyst from requiring pre-oxidation to inherently stable oxidized states. The monolayer metal atoms on oxide supports naturally exist in stable oxidation states (e.g., Cu+, Ag+, Au3+) that do not require high-temperature pre-oxidation treatment. These oxidized monolayer structures maintain high catalytic activity without the stability issues of conventional metallic catalysts, eliminating the need for pre-oxidation steps and improving operational reliability.
Solution Approach 2:
The oxide support acts as an intermediary that stabilizes the metal monolayer in active oxidized states. The strong metal-support interaction (SMSI) between the monolayer metal atoms and the oxide surface prevents sintering and maintains structural integrity, while the oxide support provides oxygen reservoirs and facilitates charge transfer, enabling the catalyst to maintain high activity and stability without requiring pre-oxidation treatment.
3Productivity
If catalysts are designed for high activity in dry conditions, then productivity increases, but performance deteriorates in the presence of water
Solution Approach 1:
The patent changes the hydrophobicity parameter of the catalyst surface through the selection of hydrophobic oxide supports and monolayer metal configurations. The combination of hydrophobic oxide surfaces (e.g., TiO2, CeO2) with monolayer metal atoms creates a water-resistant catalytic interface that maintains high activity in the presence of water. This parameter change allows the catalyst to differentiate between water molecules and target substrates, preserving productivity while achieving water stability.
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 catalysts achieve high activity and selectivity in MTM and PROX reactions, maintaining performance in the presence of water and preventing overoxidation, with the ability to meet or exceed the 50/50 goal for CO conversion in a single pass, reducing processing costs and energy requirements.
Implementation Method 1
a doped atomic monolayer, such as graphene or hexagonal boron nitride, with a nickel-based component that utilizes electronic atomic monolayer-metal support interaction (EAMSI) to control the activation of small molecules like oxygen
Implementation Method 2
enabling efficient oxidation reactions at low temperatures and preventing overoxidation
Implementation Method 3
The catalysts achieve high activity and selectivity in MTM and PROX reactions, maintaining performance in the presence of water and preventing overoxidation
Data Source
AI summary
Disclosed are catalysts that include a doped atomic monolayer (e.g., graphene or hexagonal boron nitride) bonded to a nickel-based component. The dopant can be a transition metal or nonmetal dopant and the nickel-based component can be pure nickel (e.g., Ni(111)) or nickel/metal alloys. Also disclosed are processes for catalyzing reactions that include adsorbing a small molecule to the catalyst and contacting the adsorbed small molecule with a reactant. Catalyzed reactions include oxidation reactions including oxidation of methane to methanol, oxidation of carbon monoxide (e.g., in a PROX reaction).