Synthesis of AFX Type Zeolite Membrane for Separating Dilute CO2 by Molecular Sieve Mechanism

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K19864
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 64:Environmental conservation measure and related fields
• Research Institution: Nagaoka University of Technology
• Principal Investigator: Himeno Shuji 長岡技術科学大学, 工学研究科, 准教授 (60334695)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: ゼオライト膜

Outline of Final Research Achievements

In this study, we focused on zeolite membranes that can separate CO2 and N2 efficiently from CO2 and N2 mixed gas such as combustion exhaust gas, which can save energy and cost. The AFX zeolite is an oxygen 8-membered ring zeolite with pores of 0.34 nm × 0.36 nm and has a pore diameter intermediate between the molecular system of CO2 and N2, so it can be separated by the molecular sieving effect and the separation membrane As expected.We developed AFX zeolite membrane and evaluated CO2 / N2 permeation performance. First, it was clarified that high purity AFX zeolite can be synthesized by using FAU zeolite with Si / Al = 15 by crystal synthesis using zeolite conversion method.
In AFX zeolite membrane synthesis, zeolite conversion method is adapted to membrane synthesis, and zeolite membrane that exhibits molecular sieving effect can be synthesized under the conditions of SDA / SiO2 = 0.15, NaOH / SiO2 = 0.8, H2O / SiO2 = 43, synthesis time 96h It was revealed.

Free Research Field

環境工学

Academic Significance and Societal Importance of the Research Achievements

温室効果ガス排出量実質ゼロを目指し二酸化炭素（CO2）を回収して利用する技術が革新的技術として全世界で鋭意研究されている。しかし、大気中の窒素（N2）、酸素(O2)分子(0.36nm)とCO2分子(0.32nm)は分子径が0.03nmしか違わず、CO2分子と完全に分離可能な膜は存在しない。大気中主成分であるN2とCO2を分離可能と考えられるAFX型ゼオライト(AFX)を膜化し、N2分子を分離可能とすることは新規高性能分離素材の探究に加え、世界的な緊急課題であるCO2分子の分離・回収の新しい学術分野の創成に貢献できる。