Single-Atom Catalyst with Molecular Sieve Confined Domains
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Solution Overview
Problem
Current single-atom catalysts face challenges with oxygen resistance, catalytic activity, sulfur resistance, and stability, particularly in CO-SCR reactions, due to the coexistence of nanoparticles and poor stability of precious metals under conventional impregnation conditions.
Innovation Solution
A single-atom catalyst with molecular sieve-confined domains is developed, where bimetallic ions are uniformly dispersed within the molecular sieve using a post-processing or in-situ synthesis method, leveraging oxygen vacancies and aluminum-rich sites for enhanced NO adsorption and dissociation, improving catalytic activity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional impregnation conditions are used to load metal catalysts, then the preparation process is simple, but single atoms and nanoparticles coexist resulting in poor catalytic activity
Solution Approach 1:
The patent employs molecular sieve materials with well-defined microporous structures to confine and stabilize single metal atoms. The porous framework provides specific binding sites within the pores that anchor individual metal atoms, preventing nanoparticle formation while maintaining uniform dispersion. This resolves the contradiction by using the porous structure to achieve both simple preparation (impregnation into pores) and high catalytic activity (single-atom dispersion).
Solution Approach 2:
The invention creates local regions within the molecular sieve pores where metal atoms are specifically confined and stabilized. The local chemical environment within the pores differs from the bulk material, providing unique binding characteristics that stabilize single atoms. This local quality enhancement enables high catalytic activity while maintaining preparation simplicity.
2Reliability
If precious metals are used as active components for CO-SCR in oxygen-containing atmospheres, then catalytic activity is improved, but stability and sulphur resistance deteriorate
Solution Approach 1:
The patent creates composite catalyst systems where precious metal single atoms are supported on molecular sieve materials. The molecular sieve component provides structural stability and sulphur resistance, while the precious metal single atoms provide high catalytic activity. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The molecular sieve acts as an intermediary carrier that protects the precious metal single atoms from deactivation by sulfur and maintains their stability. The sieve framework mediates between the precious metal atoms and the reaction environment, providing a stable platform that enhances both stability and sulphur resistance while preserving catalytic activity.
3Reliability
If metal particle size is reduced to single atoms for CO-SCR, then oxygen resistance is improved, but stability deteriorates under conventional impregnation conditions
Solution Approach 1:
The molecular sieve porous structure provides confinement effects that stabilize single metal atoms against aggregation and deactivation. The pore walls physically constrain the metal atoms, preventing their movement and aggregation even under oxidizing conditions. This resolves the contradiction by using the porous framework to simultaneously achieve oxygen resistance and stability.
Solution Approach 2:
The molecular sieve structure provides self-stabilization for the single metal atoms through its inherent pore structure and binding sites. The sieve material automatically confines and protects the metal atoms without requiring additional stabilizing agents or complex preparation steps. This self-service mechanism enables both oxygen resistance and stability to be achieved simultaneously.
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 catalyst exhibits high denitrification efficiency and N2 selectivity in CO-SCR reactions, with improved sulfur resistance and stability, demonstrating a broad application prospect in reducing NO emissions.
Implementation Method 1
bimetallic ions are confined in a physical structure of the molecular sieve by utilizing the physical structure and a chemical anchoring action of the molecular sieve
Implementation Method 2
bimetallic ions are confined in a physical structure of the molecular sieve by utilizing the physical structure and a chemical anchoring action of the molecular sieve
Implementation Method 3
oxygen vacancies on surfaces of the precious metals and transition metals are jointly used as adsorption sites for NO
Implementation Method 4
oxygen vacancies on surfaces of the precious metals and transition metals are jointly used as adsorption sites for NO, so that the catalysts show excellent catalytic activity
Implementation Method 5
the CO-SCR reaction in oxygen-containing atmospheres achieves high denitrification efficiency and high N2 selectivity
Data Source
AI summary
A single-atom catalyst with molecular sieve-confined domains and a preparation method and application thereof are provided in the present disclosure. According to the present disclosure, the physical structure and chemical anchoring action of the molecular sieve are utilized to confine the bimetallic ions, so that the bimetallic ions of the catalyst are dispersed in single atoms, electrons in the bimetallic ions are transferred from transition metals to precious metals to promote d-π* orbital hybridization to enhance NO adsorption, and an electron-rich environment and sufficient active sites are provided for NO adsorption and dissociation in the CO-SCR reaction; the transition metals adsorb CO to promote the transformation of N2O, NO2 and other intermediates into N2, and the transition metal serves as a sacrificial site for the poisoning of SO2 to enhance the sulphur-resistant property of the catalyst.