Zeolite-Encapsulated Metal Catalyst for Selective CO Oxidation
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Solution Overview
Problem
Conventional methods for removing CO and C3-hydrocarbons from refinery streams are non-selective, leading to unwanted side reactions and increased costs due to the production of NOx, which requires additional processing equipment and costs for selective catalytic reduction.
Innovation Solution
A method using a small pore zeolite-encapsulated metal catalyst, comprising 0.01 wt % to 10 wt % of Ru, Rh, Pd, Os, Ir, Pt, Ni, Au, or Ag, to selectively oxidize CO and C3-hydrocarbons, minimizing the interaction with larger hydrocarbon compounds and reducing NOx production by encapsulating the catalytic metal within a small pore zeolite structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional noble metal catalysts are used for CO oxidation, then CO removal efficiency is improved, but selectivity deteriorates leading to unwanted side reactions and NOx production
Solution Approach 1:
The patent employs a small pore zeolite structure with 8-membered ring channels that acts as a molecular sieve. The pore size is specifically designed to allow CO molecules to access the encapsulated noble metal catalyst while blocking larger hydrocarbonaceous compounds and nitrogen-containing compounds from reaching the catalyst surface. This selective mass transport through the porous zeolite structure enables high CO oxidation efficiency while preventing NOx formation by excluding nitrogen compounds.
Solution Approach 2:
The patent encapsulates noble metal catalyst particles within the cavities of the zeolite structure. The nested configuration places the active catalytic metal inside the zeolite pores, creating a hierarchical structure where the zeolite serves as both support and selective barrier. This nesting arrangement ensures that only molecules small enough to penetrate the zeolite pores can access the encapsulated metal catalyst, providing intrinsic selectivity for CO oxidation.
2Productivity
If conventional noble metal catalysts are used for CO oxidation, then CO removal is achieved, but additional processing equipment is required for NOx control
Solution Approach 1:
The zeolite-encapsulated catalyst performs multiple functions simultaneously: (1) it oxidizes CO to CO2 with high efficiency, (2) it selectively excludes nitrogen-containing compounds to prevent NOx formation, and (3) it protects the noble metal from deactivation by larger hydrocarbonaceous compounds. This multi-functionality eliminates the need for separate NOx control equipment, as the single catalyst system inherently prevents NOx formation through its selective permeability.
3Productivity
If conventional catalysts are used, then CO oxidation occurs, but catalyst deactivation by poisoning and sintering happens
Solution Approach 1:
The encapsulation of noble metal catalyst particles within the zeolite cavities provides physical protection against deactivation mechanisms. The zeolite structure acts as a protective shell that prevents direct contact between the catalyst and deactivating species in the feed stream, such as sulfur compounds and heavy hydrocarbons that cause poisoning. The rigid zeolite framework also prevents catalyst sintering by maintaining fixed particle positions and preventing aggregation under reaction conditions.
Solution Approach 2:
The zeolite porous structure allows selective mass transport while providing a stable framework that protects the encapsulated catalyst. The porous walls of the zeolite crystals act as a barrier against deactivating species while permitting CO diffusion to the catalyst. This selective protection mechanism maintains catalyst activity and stability over extended operation periods.
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 approach effectively converts CO to CO2 while minimizing the conversion of larger hydrocarbon compounds and nitrogen-containing compounds, maintaining catalyst activity over time and reducing the need for additional processing equipment by selectively oxidizing CO and C3-hydrocarbons, thereby reducing NOx production.
Implementation Method 1
exposing a feed comprising a) CO, C3− hydrocarbonaceous compounds, or a combination thereof, and b) at least one additional hydrocarbon, hydrocarbonaceous compound, or combination thereof, to an oxidizing environment in the presence of a small pore zeolite-encapsulated metal catalyst to oxidize at least a portion of the CO
Implementation Method 2
to oxidize at least a portion of the CO, C3− hydrocarbons, or a combination thereof
Implementation Method 3
a small pore zeolite-encapsulated metal catalyst... having a largest pore channel based on an 8-member ring size
Data Source
AI summary
Systems and methods are provided for selective oxidation of CO and/or C3− hydrocarbonaceous compounds in a reaction environment including hydrocarbons and/or hydrocarbonaceous components. The selective oxidation can be performed by exposing the CO and/or C3− hydrocarbonaceous compounds to a catalytic metal that is encapsulated in a small pore zeolite. The small pore zeolite containing the encapsulated metal can have a sufficiently small pore size to reduce or minimize the types of hydrocarbons or hydrocarbonaceous compounds that can interact with the encapsulated metal.