STT-type zeolite catalyst for SCR NOx conversion
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Solution Overview
Problem
Existing zeolite catalysts, such as SSZ-13, have limited catalytic activity in Selective Catalytic Reduction (SCR) reactions due to insufficient strongly acidic sites, which affects NOx conversion efficiency and leads to NOx slip.
Innovation Solution
Development of novel STT-type zeolite materials with a higher mole ratio of tetravalent to trivalent elements, characterized by specific x-ray diffraction patterns, synthesized using an aqueous reaction mixture with N,N,N-trimethyl-1-adamantamonium hydroxide as a structure directing agent, followed by dealumination and impregnation with metals like Cu, Fe, Co, or Ti to enhance catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional zeolite catalysts like SSZ-13 are used, then the catalyst structure is stable and manufacturable, but the catalytic activity is insufficient due to limited strongly acidic sites
Solution Approach 1:
The patent modifies the chemical composition parameters of the zeolite by incorporating tetravalent elements (Ti, Zr, Sn) in addition to traditional aluminum, creating a novel STT-type zeolite structure with enhanced acidic properties. This compositional parameter change directly increases the number and strength of acidic sites while maintaining structural stability
Solution Approach 2:
The invention creates a composite zeolite structure by combining multiple element types (Si, Al, Ti/Zr/Sn) within the same framework, forming a new STT-type material that exhibits synergistic properties. The composite nature of the zeolite framework provides both structural stability and enhanced catalytic activity
2Productivity
If the zeolite structure is optimized for high catalytic activity, then NOx conversion efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The patent incorporates tetravalent elements during the initial zeolite synthesis stage rather than attempting post-synthesis modification. This preliminary incorporation ensures uniform distribution of active sites throughout the framework and simplifies the manufacturing process by combining structure formation and catalyst activation in one step
3Productivity
If more strongly acidic sites are introduced to improve catalytic activity, then SCR reaction efficiency increases, but the cost of catalyst preparation increases
Solution Approach 1:
The patent introduces tetravalent elements at specific framework positions within the zeolite structure where they can maximize acidic site density and strength. This localized optimization of quality ensures high catalytic activity per unit of expensive metal content, improving cost-effectiveness
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 novel PIDC-type zeolites exhibit significantly stronger acidic sites than SSZ-13, demonstrating superior catalytic activity in SCR reactions with increased NOx conversion performance and reduced NOx slip, as evidenced by temperature programmed desorption studies.
Implementation Method 1
maintaining the aqueous mixture under crystallization conditions sufficient to crystallize crystals of a zeolite type material
Implementation Method 2
The metal cations from the metal salt solution occupy sites in the zeolite framework previously occupied by aluminum (Al) cations
Implementation Method 3
Temperature Programmed Desorption (TPD) studies for both ammonia and N-propylamine on the new PIDC type materials, indicate that they contain more strongly acidic sites
Data Source
AI summary
The present disclosure generally provides novel STT-type zeolite materials called PIDC-120501, PIDC-120502, and PIDC-120805/120806 or PIDC-type zeolites and a method of making these zeolites. The present disclosure also provides for the use of these zeolite materials as a catalyst and a method of preparing said catalyst. The PIDC-type zeolites or STT-type zeolite materials may be used as a catalyst, such as in Selective Catalytic Reduction (SCR) applications.