β-Type Iron Silicate Catalyst Synthesis via Fluorine Parameter Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current β-type iron silicates lack high heat resistance and crystallinity with iron in a highly dispersed state, making them insufficient for industrial use as catalysts or adsorbents, especially when synthesized without fluorine, which is difficult to use industrially due to corrosion issues and potential performance impacts.
Innovation Solution
A β-type iron silicate with a fluorine content not more than 400 ppm, characterized by truncated square bipyramidal morphology and a high SiO2/Al2O3 molar ratio of 300 or more, containing iron in a highly dispersed state within the framework, synthesized through a hydrothermal process with specific starting-material compositions to achieve high crystallinity and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If iron is introduced into zeolite framework by hydrothermal synthesis to achieve high dispersion, then metal dispersion is improved, but the range of starting-material compositions capable of crystal formation becomes narrower and synthesis time becomes excessively prolonged
Solution Approach 1:
The patent changes the chemical composition parameters of the starting materials by introducing fluorine at controlled concentrations (0.01-5 wt% relative to silicon source) and adjusting the SiO2/Al2O3 molar ratio to 100-1000. These parameter modifications enable crystal formation within 1-72 hours while maintaining high iron dispersion (5-50 wt% Fe2O3) and preventing iron aggregation, thus resolving the contradiction between achieving high metal dispersion and reducing synthesis time.
2Reliability
If fluorine is added to starting materials to improve crystallinity and reduce lattice defects, then crystallinity is improved, but equipment corrosion increases and residual fluorine may adversely affect performance
Solution Approach 1:
The patent optimizes the fluorine concentration parameter to a specific range of 0.01-5 wt% relative to the silicon source, which is sufficient to improve crystallinity and reduce lattice defects but low enough to minimize equipment corrosion and residual fluorine impacts. This parameter optimization enables the simultaneous achievement of high crystallinity and reduced harmful effects.
3Manufacturing precision
If aluminum content in starting materials is decreased to reduce coexistence with iron, then iron dispersion is improved, but the range of starting-material compositions capable of crystal formation becomes narrower
Solution Approach 1:
The patent introduces fluorine as a key parameter that expands the compositional range for crystal formation. With fluorine present at 0.01-5 wt%, the system can accommodate lower aluminum content (SiO2/Al2O3 molar ratio of 100-1000) while still achieving successful crystal formation. This enables high iron dispersion (5-50 wt% Fe2O3) without the need for high aluminum content, thus resolving the contradiction between iron dispersion and compositional flexibility.
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 resulting β-type iron silicate maintains high crystallinity even after 1,000°C endurance treatment, enabling its use as a high-performance catalyst or adsorbent at elevated temperatures without the limitations of fluorine usage.
Implementation Method 1
atoms of the metals being introduced are separately incorporated into the silicon network including oxygen atoms by adding the metals as a starting material for hydrothermal synthesis of a zeolite
Implementation Method 2
a method in which metal cations are loaded into a zeolite by means of ion exchange in a liquid phase while utilizing the ability of the zeolite to undergo ion exchange
Implementation Method 3
a method in which a zeolite is impregnated with a solution containing a salt of a metal to thereby load the metal into the zeolite
Implementation Method 4
the full width at half maximum of an X-ray diffraction peak
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to: a β-type iron silicate which has a fluorine content not more than 400 ppm by weight on a dry basis and in which the crystal grains have a truncated square bipyramidal morphology in an examination with a scanning electron microscope and the whole or part of the iron is contained in the β-type framework structure, and a process for producing the iron silicate; a β-type iron silicate which has an SiO2/Fe2O3 molar ratio of 50-150, a fluorine content not more than 400 ppm by weight of the dry crystals, and a full width at half maximum of the crystal diffraction (302) plane of 0.16-0.24° and in which the whole or part of the iron is contained in the β-type framework structure, and a process for producing the iron silicate; and a nitrogen oxide removal catalyst containing a β-type iron silicate which has iron and aluminum in the β-type framework structure, has an SiO2/Al2O3 molar ratio of 20-70 and an SiO2/Fe2O3 molar ratio of 50-200, and has a full width at half maximum of the crystal diffraction (302) plane of 0.30-0.40°, a process for producing the catalyst, and a method for nitrogen oxide removal with the catalyst.