CHA Framework Molecular Sieve Synthesis via One-Pot Process
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Solution Overview
Problem
Current methods for synthesizing molecular sieves with CHA framework type are complex, costly, and environmentally unfriendly, limiting the large-scale application of SCR catalysts in China.
Innovation Solution
A direct synthesis method for H-type molecular sieves with CHA framework type using specific structure-directing agents, such as Compound A and Compound B, without an ammonium exchange process, and incorporating samarium as an active ingredient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to synthesize molecular sieves with CHA framework type, then the molecular sieve can be produced, but the synthesis cycle is long and the process is complex
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing a molecular sieve with CHA framework type and amorphous aluminum phosphate in a one-pot process before the actual SCR catalyst formation. This pre-formed molecular sieve serves as a template and structural foundation, eliminating the need for subsequent complex ion exchange steps and significantly reducing the overall synthesis cycle time while maintaining framework integrity.
Solution Approach 2:
The patent merges multiple synthesis steps into a single one-pot process. Instead of separately synthesizing the molecular sieve framework, performing ion exchange, and then forming the SCR catalyst, the method combines the formation of CHA framework type molecular sieve and amorphous aluminum phosphate into one integrated reaction system, thereby simplifying the overall process and reducing operational complexity.
2Ease of manufacture
If conventional synthesis methods are used, then molecular sieves can be produced, but the production cost is high
Solution Approach 1:
The patent extracts and eliminates the costly and complex ion exchange step from the conventional synthesis process. By directly synthesizing the molecular sieve with CHA framework type and amorphous aluminum phosphate in one pot, the method removes the need for separate ion exchange operations, thereby reducing material costs, energy consumption, and production complexity while maintaining product quality.
Solution Approach 2:
The preliminary formation of the molecular sieve framework with integrated amorphous aluminum phosphate eliminates subsequent processing steps. This pre-formed structure serves as the direct precursor for SCR catalyst formation, avoiding the need for expensive ion exchange materials and reducing overall production costs while simplifying the manufacturing process.
3Object-affected harmful factors
If conventional methods are used, then molecular sieves can be synthesized, but waste liquid disposal becomes difficult
Solution Approach 1:
The patent converts the potentially harmful waste liquid byproduct into a beneficial component. The amorphous aluminum phosphate formed during the one-pot synthesis serves as both a structural component of the molecular sieve and a catalyst promoter. This eliminates waste liquid disposal issues while simultaneously improving the catalytic performance of the final SCR catalyst.
Solution Approach 2:
By merging the synthesis of molecular sieve framework, amorphous aluminum phosphate formation, and SCR catalyst preparation into one integrated process, the method eliminates separate waste liquid generation steps. The combined reaction system ensures that all byproducts are incorporated into the final catalyst structure, eliminating environmental pollution and simplifying waste disposal.
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
This method enables the efficient and cost-effective production of molecular sieves with high relative crystallinity, suitable for large-scale production of SCR catalysts, which exhibit excellent low-temperature activity, wide temperature windows, and improved nitrogen selectivity.
Implementation Method 1
A structure-directing agent for synthesizing a molecular sieve having CHA framework type includes at least one of Compound A and Compound B
Implementation Method 2
adding a silicon source and a seed crystal into the sol-gel, and performing a hydrothermal synthesis reaction in a hydrothermal synthesis reactor to obtain a reaction solution
Implementation Method 3
filtering the reaction solution, cleaning a filter cake, and heating to obtain an H-type molecular sieve having CHA framework type
Data Source
AI summary
An H-type molecular sieve having the CHA framework type is directly prepared through hydrothermal synthesis by using the compounds with the chemical formulas (C4H8NO)3PO and/or (C4H8NO)2PO(C4H10N) as structure-directing agents. The structure-directing agent has a molecular topological structure, which is conducive to quickly and efficiently building a molecular sieve having the CHA framework type, so that the prepared product has a regular morphology and high relative crystallinity. The synthesis method can directly synthesize the H-type molecular sieve having the CHA framework type with a relative crystallinity greater than 95%. The molecular sieve product can be obtained by direct drying and calcination without an ammonium exchange process, so the synthesis method is simple, easy to perform, and suitable for large-scale production. The samarium-based CHA molecular sieve catalyst shows excellent ammonia adsorption capacity, low-temperature activity, active temperature window, N2 selectivity, and structural stability in the NH3-SCR technology.