On the Reactivity of Ammonia in Metal-Organic Frameworks

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23648
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0502:Inorganic/coordination chemistry, analytical chemistry, inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: The University of Tokyo (2020); Tokyo Institute of Technology (2019)
• Principal Investigator: Ogiwara Naoki 東京大学, 大学院総合文化研究科, 助教 (70848267)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: 多孔性金属錯体 / ナノ結晶 / 触媒

Outline of Final Research Achievements

The reactivity of H2O vapor in metal－organic frameworks (MOFs) was first studied with Pt nanocrystals (NCs) through the water－gas shift (WGS) reaction. A water-stable MOF, UiO-66, serves as a highly effective support material for the WGS reaction compared with ZrO2. The origin of the high catalytic performance was investigated using in situ IR spectroscopy. Besides, the ligand functionalization of UiO-66 significantly affected the catalytic performance of the WGS reaction. The introduction of a －Br group lowered the reactivity of Pt@UiO-66 by nearly half, whereas the substitution of －Br with a －Me2 group triply enhanced the activity. The origin of the enhanced catalytic activity was found to be the change in H2O activity in the UiO-66 pores by the ligand functionalization, which was investigated using H2O sorption, solid-state NMR, X-ray photoelectron spectroscopy, and in situ IR measurements. This work opens a new prospect to develop MOFs as a platform to activate H2O.

Free Research Field

錯体化学

Academic Significance and Societal Importance of the Research Achievements

本成果はこれまで未開拓であったMOFに吸着された水の反応性についての知見を与えるものであり、水を活性化する場としてのMOFの有用性を世界に先駆けて見出した点で学術的意義を有すると考えられる。本課題で解明された水の吸着状態と反応性との相関は、水をはじめとする種々の分子の反応場を構築する上で重要な指針を与えると思われる。今後、水だけでなくアンモニアや有機分子等の分子変換に、得られた知見を適用すれば革新的触媒の創出に繋がると期待される。このように本成果は小分子活性という基礎学問の発展に寄与するだけでなく、既存の触媒を凌駕する高活性触媒の開発にも貢献するため、応用面でも波及効果をもたらすと考えられる。