MSECT-4 Molecular Sieves with OFF and ERI Topologies for SCR
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Solution Overview
Problem
Conventional molecular sieve catalysts for NOx reduction in SCR technology face issues such as lengthy synthesis cycles, limited low-temperature performance, narrow temperature windows, and high costs, along with irregular product morphology and poor consistency due to separate growth of crystalline phases.
Innovation Solution
The synthesis of bone-like msect-4 molecular sieves with OFF and ERI topologies in a suitable alkaline environment using specific structure-directing agents, such as N, N, N-trimethylamantadine and tetramethylammonium hydroxide, allows for rapid hydrothermal crystallization within 6 hours, resulting in copper-based catalysts with excellent low-temperature NH3-SCR activity and a wide temperature window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional molecular sieve catalysts are used for SCR technology, then NOx reduction is achieved, but the synthesis cycle is lengthy and low-temperature performance is limited
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating dual topologies (CHA and ERI frameworks) with specific Si/Al ratios and introducing copper as the active component. This compositional parameter change enables both rapid synthesis and superior low-temperature NOx reduction performance, resolving the contradiction between synthesis time and catalytic effectiveness.
Solution Approach 2:
The patent creates a composite molecular sieve structure combining two different framework topologies (CHA and ERI) within a single catalyst particle. This composite structure leverages the complementary properties of both frameworks, achieving rapid synthesis kinetics from the ERI phase while maintaining the catalytic activity of the CHA phase, thus resolving the time-performance contradiction.
2Adaptability or versatility
If conventional molecular sieve catalysts are used, then SCR activity is achieved, but the temperature window is narrow and costs are high
Solution Approach 1:
The patent optimizes the Si/Al ratio parameter and introduces copper loading at specific concentrations to broaden the catalytic temperature window. By adjusting these compositional parameters, the catalyst achieves high activity across a wider temperature range while maintaining cost-effectiveness through efficient synthesis procedures.
Solution Approach 2:
The patent employs a disposable template molecule approach where organic structure-directing agents are used during synthesis but are completely removed in the final product. This allows for precise control of the dual-topology structure during manufacturing without requiring expensive permanent additives, reducing overall manufacturing costs while achieving broad temperature adaptability.
3Reliability
If mixed framework types are used to enhance catalytic activity, then activity and durability are improved, but product morphology becomes irregular and consistency is poor
Solution Approach 1:
The patent merges two different molecular sieve frameworks (CHA and ERI) into a single intergrown structure that forms uniformly shaped particles. This merged structure maintains the complementary catalytic benefits of both frameworks while achieving regular bone-like morphology through their synergistic crystallization, resolving the contradiction between activity enhancement and morphological consistency.
Solution Approach 2:
The patent uses organic structure-directing agents as intermediaries during the synthesis process to guide the formation of the dual-topology structure. These intermediaries control the crystallization process to produce regular bone-like particles with consistent morphology, while their complete removal in the final product ensures no interference with catalytic performance, thus achieving both high reliability and manufacturing precision.
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 method provides msect-4 molecular sieves with intergrown phases and a regular bone-like structure, achieving excellent hydrothermal stability, low-temperature performance, and high nitrogen selectivity, suitable for industrial-scale production and applications in SCR, PNA, and FCC technologies.
Implementation Method 1
Selective catalytic reduction (SCR) technology is the most effective NOx removal technology
Implementation Method 2
passive nitrogen oxide adsorption technology (PNA)
Data Source
AI summary
The present disclosure provides msect-4 molecular sieves with OFF and ERI topologies, a preparation method therefor, and applications thereof. An eight-membered ring small pore molecular sieve used as a raw material is dispersed in an aqueous phase. Following that, caustic potash, an aluminum source, and an organic structure-directing agent (OSDA) are added. The pH value is then adjusted to be greater than 10, and a silicon source is introduced to attain the desired silicon-aluminum ratio, followed by stirring reaction, aging, crystallization, filtration, washing, ammonia exchange reaction, drying, and calcination. The msect-4 molecular sieves with OFF and ERI topologies, the preparation method therefor, and applications exhibit excellent hydrothermal stability, a plurality of adsorption sites exposed by a regular bone-like structure, and a large specific surface area. Consequently, this molecular sieves find applicability across various technical fields including selective catalytic reduction, passive adsorption, and catalytic cracking, and has broad application prospects.