Silicoaluminophosphate Catalyst Water Resistance via Composition Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Crystalline silicoaluminophosphates, such as SAPO-34, suffer from reduced crystallinity and solid acidity when exposed to water-containing atmospheres, leading to decreased catalytic activity and stability issues as solid acid catalysts.
Innovation Solution
A novel silicoaluminophosphate with a specific composition and structure, characterized by a molar fraction of Si between 0.05 and 0.15, Al between 0.47 and 0.52, and P between 0.40 and 0.46, and an intergrowth ratio of CHA and AEI structures, which maintains high water resistance and solid acidity even in humid conditions, is produced using a method involving a silicon source, phosphorus source, aluminum source, water, and a structure directing agent at controlled temperatures and durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicoaluminophosphates (such as SAPO-34) are used as solid acid catalysts, then catalytic activity is provided, but crystallinity and solid acidity decrease when exposed to water-containing atmospheres
Solution Approach 1:
The invention changes the compositional parameters by controlling the Si/Al ratio to be within 0.05-0.15 and using specific crystallization conditions (temperature, time, structure directing agents) to produce a silicoaluminophosphate with enhanced water resistance while maintaining the required crystallinity and solid acidity for catalytic activity
Solution Approach 2:
The invention creates a composite crystal structure that combines characteristics of different silicoaluminophosphate phases, resulting in a material that exhibits both high catalytic activity and improved stability in water-containing atmospheres through synergistic effects of the composite structure
2Reliability
If the Si amount is increased to improve catalytic activity, then solid acidity increases, but water resistance may be compromised
Solution Approach 1:
The invention optimizes the Si content parameter within the specific range of 0.05-0.15 molar fraction, which provides sufficient solid acidity for high catalytic activity while maintaining the water resistance required for stability in humid conditions, resolving the trade-off between these two properties
3Stability of the object's composition
If storage management blocked from atmosphere is used to maintain solid acidity, then crystallinity is preserved, but storage complexity and cost increase
Solution Approach 1:
The invention makes the silicoaluminophosphate self-stabilizing by incorporating compositional and structural features that inherently resist water-induced degradation, eliminating the need for complex blocked storage management systems and allowing straightforward storage while maintaining solid acidity and crystallinity
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 silicoaluminophosphate exhibits high water resistance, retaining at least 50% of its solid acidity after storage in saturated water vapor, enhancing its stability and catalytic performance compared to existing silicoaluminophosphates.
Implementation Method 1
a silicoaluminophosphate having high water resistance allowing only a small decrease in the solid acidity even when exposed to a water-containing atmosphere
Implementation Method 2
holding the reaction mixture at a temperature of from 170°C to 200°C for 5 to 100 hours
Data Source
Figure 1~2
AI summary
A silicoaluminophosphate represented by the following formula (1) and having a powder X-ray diffraction pattern shown in Table 1 below: (SixAlyPz)O2 (1) (wherein x is the molar fraction of Si and 0.05<x≤0.15; y is the molar fraction of Al and 0.47≤y≤0.52; z is the molar fraction of P and 0.40≤z≤0.46; and x+y+z=1); [Table 1]