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Carbon Monoxide Oxidation by Polyoxometalate‐Supported Gold Nanoparticulate Catalysts: Activity, Stability, and Temperature‐ Dependent Activation Properties
Author(s) -
Yoshida Takuya,
Murayama Toru,
Sakaguchi Norihito,
Okumura Mitsutaka,
Ishida Tamao,
Haruta Masatake
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201710424
Subject(s) - polyoxometalate , catalysis , carbon monoxide , adsorption , colloidal gold , chemistry , inorganic chemistry , nanoparticle , colloid , chemical engineering , transition metal , materials science , nanotechnology , organic chemistry , engineering
Nanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs 4 [α‐SiW 12 O 40 ]⋅ n H 2 O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was −67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Au δ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions.