MWF-type Zeolite CO2/CH4 Separation via XRD Peak Control
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Solution Overview
Problem
Existing MWF-type zeolites are insufficient for high-selectivity gas separation, particularly in separating carbon dioxide and methane from natural gas, due to high crystal lattice distortions and defects, which affect their adsorption efficiency.
Innovation Solution
An MWF-type zeolite with specific diffraction peak intensity ratios and half-value widths, produced using a mixed gel with controlled molar ratios of silica, aluminum, alkali metals, and water, and an organic structure-directing agent, to enhance crystallinity and selectivity for carbon dioxide over methane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MWF-type zeolites are used for gas separation, then the separation process can be implemented, but the selectivity for carbon dioxide over methane is insufficient due to crystal lattice distortions and defects
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar ratios of components in the gel mixture (SiO2/Al2O3=5-15, Na2O/Al2O3=1-3, H2O/Al2O3=100-500) and adjusting synthesis conditions (temperature 100-200°C, time 1-7 days) to obtain MWF-type zeolite with reduced crystal lattice distortions and defects, thereby improving CO2/CH4 selectivity to 23 or more
2Reliability
If the crystallinity of MWF-type zeolite is improved to enhance adsorption selectivity, then carbon dioxide selectivity increases, but the manufacturing process becomes more complex requiring precise control of multiple parameters
Solution Approach 1:
The patent systematically optimizes multiple synthesis parameters including gel composition ratios (SiO2/Al2O3, Na2O/Al2O3, H2O/Al2O3), synthesis temperature (100-200°C), and time (1-7 days) to achieve the target XRD peak ratios (13.8°/11.1°=0.63-0.80, 51.6°/11.1°=0.36-0.52) and half-value width (≤0.31°), thereby improving crystallinity and CO2 selectivity
Solution Approach 2:
The patent uses XRD analysis as a feedback mechanism to characterize the synthesized zeolite structure by measuring peak intensities at 11.1°, 13.8°, and 51.6° and half-value widths, comparing results against target ranges to determine whether the synthesis conditions achieved the desired crystallinity and structural quality for high CO2/CH4 selectivity
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 zeolite exhibits improved crystallinity and high selectivity for carbon dioxide adsorption, effectively separating carbon dioxide from methane, with a CO2/CH4 adsorption ratio of 23 or more, suitable for industrial gas separation applications.
Implementation Method 1
ZSM-25 selectively adsorbs carbon dioxide and thus is used for separation of carbon dioxide and methane and/or separation of carbon dioxide and nitrogen
Implementation Method 2
when heights of peaks around 2θ=11.1 and 13.8° in a peak obtained by X-ray diffraction are defined as A and B, respectively
Data Source
AI summary
An MWF-type zeolite, wherein, when the heights of peaks around 2θ=11.1 and 13.8° in a peak obtained by X-ray diffraction are defined as A and B, respectively, 0.63≤B/A≤0.80 satisfied.