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Chlorine‐Tolerant Ruthenium Catalyst Derived Using the Unique Anion‐Exchange Properties of 12 CaO⋅7 Al 2 O 3 for Ammonia Synthesis
Author(s) -
Li Jiang,
Kitano Masaaki,
Ye TianNan,
Sasase Masato,
Yokoyama Toshiharu,
Hosono Hideo
Publication year - 2017
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201700353
Subject(s) - catalysis , ammonia production , chemistry , ammonia , chlorine , ion , ruthenium , inorganic chemistry , adsorption , ion exchange , organic chemistry
Abstract Poisoning is defined as deactivation by the strong adsorption of, usually, impurities on active sites, which is a serious problem in many important catalytic processes. For example, the activity of Ru catalysts is significantly degraded by Cl in ammonia synthesis because of its electron‐withdrawing properties. Here we demonstrate that 12 CaO⋅7 Al 2 O 3 with subnanometer‐sized cages prevents the poisoning of a Ru catalyst by Cl − ions in ammonia synthesis. Conventional supported Ru catalysts exhibit a negligible activity if a tiny amount of Cl − ions remain on the catalyst surface. In contrast, the catalytic activity of Ru/C12A7 is not influenced by Cl − ions even though the amount of Cl in Ru/C12A7 is one order of magnitude higher than that in the conventional Ru catalysts. The Cl resistance of Ru/C12A7 is attributed to the unique anion‐exchange properties of C12A7; that is, the Cl − ions are trapped preferentially in the positively charged subnanometer‐sized cages of C12A7 instead of OH − ions under ammonia synthesis conditions.