Zeolite Membrane Composition for CO2 and N2 Separation from Methane
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Solution Overview
Problem
Existing methods for separating CO2 and N2 from a mixed gas using zeolite membranes are inefficient and complicated, with CO2 adsorptivity inhibiting N2 permeation, leading to difficulties in simultaneous and effective separation.
Innovation Solution
A gas separation apparatus using a zeolite membrane with specific composition and structure, including a ratio of alkali metal to framework elements less than 6.0 mol% and containing aluminum, allows efficient separation of CO2 and N2 by permeation through a porous support under controlled pressure and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a zeolite membrane is used to remove CO2 from mixed gas, then CO2 separation efficiency is improved, but N2 permeation is inhibited due to CO2's high adsorptivity
Solution Approach 1:
The patent changes the chemical composition parameters of the zeolite membrane by controlling the Si/Al ratio to 2 or less and adding specific amounts of alkali metals (Na: 1-5 wt%, K: 1-5 wt%, Li: 1-5 wt%). This parameter optimization adjusts the membrane's adsorption characteristics to reduce CO2's excessive adsorptivity while maintaining separation efficiency, thereby improving N2 permeation rate.
Solution Approach 2:
The patent creates a composite zeolite membrane system by combining multiple elements (Si, Al, Na, K, Li) in specific proportions. This composite structure with controlled framework composition and embedded alkali metals modifies the membrane's interaction with CO2 and N2 molecules, achieving balanced separation performance for both gases simultaneously.
2Manufacturing precision
If separate membranes are used for CO2 and N2 removal, then separation efficiency is improved, but device complexity and size increase
Solution Approach 1:
The patent designs a single zeolite membrane that performs multiple separation functions simultaneously. By optimizing the framework composition (Si/Al ≤ 2) and adding alkali metals, the membrane achieves effective separation of both CO2 and N2 from methane in one unit, eliminating the need for multiple separate membrane stages or apparatuses.
Solution Approach 2:
The patent merges the CO2 removal function and N2 removal function into a single integrated zeolite membrane system. The combined membrane structure with specific composition (Si, Al, Na, K, Li) handles both separation tasks concurrently, simplifying the overall apparatus structure and reducing system complexity.
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 apparatus achieves simultaneous and efficient separation of CO2 and N2 from a mixed gas, suppressing excess CO2 adsorption on alkali metals and enhancing N2 permeation, with removal percentages exceeding 60% for CO2 and 30% for N2.
Implementation Method 1
a separation membrane that allows carbon dioxide and nitrogen in the mixed gas to permeate therethrough, to thereby separate carbon dioxide and nitrogen from methane. The separation membrane is made of zeolite.
Data Source
AI summary
A gas separation apparatus includes a gas supply part and a zeolite membrane. The gas supply part supplies a mixed gas at a pressure greater than or equal to 10 atm and less than or equal to 200 atm. The mixed gas contains at least CH4, CO2, and N2. A water content of the mixed gas is made less than or equal to 3000 ppm. The zeolite membrane allows CO2 and N2 in the mixed gas to permeate therethrough, to thereby separate CO2 and N2 from CH4. The zeolite membrane is made of zeolite. The zeolite contains Al. A ratio of alkali metal to whole framework elements in the zeolite is less than or equal to 6.0 mol %. An amount of substance of the alkali metal in the zeolite is less than an amount of substance of Al.