Subnanometer Catalysts for Selective Oxidative Dehydrogenation
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Solution Overview
Problem
Current catalysts for oxidative dehydrogenation of alkanes, such as propane, suffer from limited activity and selectivity due to incomplete control over catalyst cluster size and reaction site distribution, leading to energy-intensive processes and the production of unwanted products.
Innovation Solution
The development of subnanometer metal clusters with 8 to 10 atoms, supported on uniquely shaped substrates, which are stabilized using atomic layer deposition to maintain high selectivity and activity without continuous energy input, and are optimized for specific chemical reactions like propylene epoxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for oxidative dehydrogenation, then the process can proceed, but the catalysts exhibit limited activity and selectivity due to inability to control cluster size
Solution Approach 1:
The catalyst is segmented into discrete atomic clusters (4-20 atoms) rather than continuous nanoparticles or bulk material. This segmentation allows precise control over the number of atoms in each cluster, enabling optimization of both activity and selectivity while resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The invention changes the critical parameter of cluster size from uncontrolled continuous variation to discrete controlled values (4-20 atoms). By controlling this fundamental parameter, the patent achieves both high productivity through optimized cluster composition and high manufacturing precision through defined size ranges.
2Productivity
If conventional catalysts are used, then reactions can occur, but high energy input is required due to endothermic dehydrogenation process
Solution Approach 1:
The catalyst provides localized quality enhancement at the atomic cluster level, where each cluster of 4-20 atoms creates optimized electronic and geometric properties for facilitating the reaction. This local optimization enables lower energy input while maintaining high conversion rates, resolving the contradiction between productivity and energy consumption.
3Ease of manufacture
If wet chemistry is used to combine support substrate with catalyst material, then catalysts can be formed, but size distribution is poor and selectivity is reduced
Solution Approach 1:
The patent replaces wet chemistry methods with physical vapor deposition techniques to form catalyst clusters on support substrates. This substitution eliminates the size distribution problems inherent in wet chemistry while maintaining ease of manufacture, resolving the contradiction between manufacturing simplicity and size precision.
4Productivity
If catalysts operate at typical operating temperatures, then reactions proceed, but high temperature operation is required for adequate activity
Solution Approach 1:
The invention creates composite atomic clusters (4-20 atoms) with optimized electronic structures that enable high reaction activity at lower temperatures. These composite structures combine multiple elements or configurations to achieve catalytic performance without requiring high operating temperatures, resolving the contradiction between productivity and temperature requirements.
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 exhibit high activity and selectivity for oxidative dehydrogenation and epoxidation reactions, with sustained performance over extended periods at lower temperatures, avoiding the formation of unwanted products and reducing energy demands.
Implementation Method 1
Oxidative dehydrogenation (ODH) of propane to propylene is a multibillion dollar industrial process
Implementation Method 2
U.S. Pat. No. 5,623,090 issued to Haruta et al on Apr. 22, 1997 discloses catalysts comprising gold particles deposited on titanium oxide carrier. These catalysts were used to produce alcohol, ketone, and epoxides via oxidation of hydrocarbons
Implementation Method 3
The development of subnanometer metal clusters with 8 to 10 atoms, supported on uniquely shaped substrates, which are stabilized using atomic layer deposition
Data Source
AI summary
Highly uniform cluster based nanocatalysts supported on technologically relevant supports were synthesized for reactions of top industrial relevance. The Pt-cluster based catalysts outperformed the very best reported ODHP catalyst in both activity (by up to two orders of magnitude higher turn-over frequencies) and in selectivity. The results clearly demonstrate that highly dispersed ultra-small Pt clusters precisely localized on high-surface area supports can lead to affordable new catalysts for highly efficient and economic propene production, including considerably simplified separation of the final product. The combined GISAXS-mass spectrometry provides an excellent tool to monitor the evolution of size and shape of nanocatalyst at action under realistic conditions. Also provided are sub-nanometer gold and sub-nanometer to few nm size-selected silver catalysts which possess size dependent tunable catalytic properties in the epoxidation of alkenes. Invented size-selected cluster deposition provides a unique tool to tune material properties by atom-by-atom fashion, which can be stabilized by protective overcoats.