Core-Shell Zeolite Adsorbent for Hydrothermal Stability
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Solution Overview
Problem
Zeolite-based hydrocarbon adsorbents have insufficient high-temperature heat resistance, leading to structural collapse and active site loss in high-temperature humid environments, which affects their durability and performance in exhaust gas purification systems.
Innovation Solution
A core-shell hydrocarbon adsorbent is developed, comprising a zeolite core ion-exchanged with metals like Cr, Fe, and a mesoporous metal oxide shell, such as CeO2, to enhance hydrothermal stability and adsorption capacity of unsaturated hydrocarbons, prepared through a method involving mixing and calcination processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If zeolite-based hydrocarbon adsorbent is used, then adsorption capacity of unsaturated hydrocarbons is improved, but hydrothermal stability deteriorates due to structural collapse above 850°C
Solution Approach 1:
The patent creates a core-shell composite structure where a zeolite core (providing hydrocarbon adsorption capacity) is coated with a metal oxide shell (providing hydrothermal stability). This composite structure allows the material to simultaneously achieve high adsorption capacity for unsaturated hydrocarbons and resistance to structural collapse at temperatures above 850°C in humid environments, resolving the contradiction between adsorption performance and hydrothermal stability.
2Temperature
If zeolite-based hydrocarbon adsorbent is installed on underfloor, then heat resistance is improved, but warm-up rate of three-way catalyst decreases
Solution Approach 1:
The patent modifies the physical and chemical parameters of the adsorbent material by introducing a metal oxide shell with controlled thickness and composition. This allows the adsorbent to maintain heat resistance while improving thermal conductivity and reducing thermal mass, thereby enabling faster catalyst warm-up rates when installed on the underfloor, resolving the contradiction between heat resistance and warm-up speed.
3Quantity of substance
If zeolite structure is used, then adsorption sites are increased, but structural collapse occurs in high-temperature humid environment
Solution Approach 1:
The patent applies local quality protection by placing the metal oxide shell specifically on the outer surface and pore entrances of the zeolite particles. This localized coating preserves the internal zeolite structure and its active sites for hydrocarbon adsorption while protecting the overall structure from collapse in high-temperature humid environments, resolving the contradiction between having numerous active sites and maintaining structural 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 core-shell structure significantly improves hydrothermal stability and adsorption performance, preventing structural collapse and active site loss, thereby enhancing the durability and effectiveness of the adsorbent in high-temperature humid conditions.
Implementation Method 1
the core-shell structure significantly improves hydrothermal stability and adsorption performance, preventing structural collapse and active site loss
Implementation Method 2
the core includes ion-exchanged zeolite that is ion-exchanged with a metal other than silicon (Si) and aluminum (Al)
Implementation Method 3
the shell includes a mesoporous metal oxide... having a high adsorption amount of unsaturated hydrocarbons
Data Source
AI summary
A hydrocarbon adsorbent includes a core-shell particle including a core and a shell surrounding the core, wherein the core includes ion-exchanged zeolite that is ion-exchanged with a metal other than silicon (Si) and aluminum (Al) and the shell includes a mesoporous metal oxide.