Improvement of accuracy of adsorption isotherm measurement in low-pressure region

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23574
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0401:Materials engineering, chemical engineering, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Hiraide Shotaro 京都大学, 工学研究科, 助教 (60853207)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: 吸着等温線 / 高精度測定 / 真空 / リーク

Outline of Final Research Achievements

The pressure increase in the low-pressure region, which adversely affects the accuracy of adsorption isotherm measurement, was investigated by combining an adsorption measurement system with a quadrupole mass spectrometer. It was found that nitrogen and oxygen were the dominant causes of the pressure increase in the blank cell, with a small amount of carbon dioxide and water also included. On the other hand, when Y-type zeolites was placed in the sample cell, the pressure increase was caused almost exclusively by nitrogen. In other words, the pressure increase during the adsorption measurement was mainly caused by the leakage of outside air. A program was developed to calculate the true equilibrium pressure by analyzing the partial pressure of the leaked gas from the trend data during the adsorption measurement, and it was shown that the adsorption isotherm in the low-pressure region could be reasonably corrected.

Free Research Field

吸着工学

Academic Significance and Societal Importance of the Research Achievements

吸着分子サイズの細孔径を有する多孔体は，吸着分子と強く相互作用するために，低圧環境においても吸着が進行する。裏を返せば，低圧領域における吸着挙動にこそ，その材料の特性が色濃く出るはずであり，本研究で構築した吸着等温線の高精度測定プロトコルによって，より詳細に，かつ再現性よく材料の細孔状態を議論できるようになる。そのため，昨今脚光を浴びている，ターゲットとなる吸着ガスに適した細孔をもつ多孔体を分子レベルで機能設計する研究がより活発となり，吸着や膜分離といった多孔性材料を用いた手法の高効率化，ひいては産業全体におけるエネルギー消費の約半分を占める分離工程の刷新に繋がる成果であると考えている。