TY - JOUR

T1 - Synthesis and Investigation of Finely Dispersed Calcium Aluminates and Catalysts Based on Them

AU - Shuvarakova, E. I.

AU - Bedilo, A. F.

AU - Kenzhin, R. M.

AU - Ilyina, E. V.

AU - Gerus, Y. Y.

N1 - Funding Information: This study was financially supported by the Ministry of Science and Higher Education of the Russian Federation under a state order of the Institute of Catalysis, Siberian Branch, Russian Academy of Sciences (registration number AAAA-A21-121011390054-1). Publisher Copyright: © 2022, Pleiades Publishing, Ltd.

PY - 2022/6

Y1 - 2022/6

N2 - Finely dispersed calcium aluminate C12A7 (12CaO⋅7Al2O3) samples are synthesized in water and in an autoclave using supercritical drying. The specific surface area of the aerogel samples reaches 330 m2/g immediately after drying in an autoclave and 170 m2/g after calcination at 500°C. Nanocrystalline materials with a mayenite crystal structure and a specific surface area of about 80 m2/g are obtained after calcination at 600°C in water by the reaction of CaO with an aluminum hydroxide suspension. The supported catalysts containing Pd, V, Fe, Ni, Cu, and Ag are synthesized by incipient wetness impregnation of the C12A7 sample obtained in water. The catalytic activity of the synthesized samples is studied in the oxidation of carbon monoxide CO. The highest catalytic activity is demonstrated by the 1% Pd/C12A7 sample. Electron-acceptor sites capable of ionizing phenothiazine molecules to its radical cations, electron-donor sites ionizing trinitrobenzene to its radical anions, and radical sites reacting with diphenylamine to form stable nitroxyl radicals are observed on the surface of all the synthesized materials based on C12A7. The formation of nitroxide radicals after the adsorption of diphenylamine indicates that oxygen radicals on the mayenite surface, which can be highly active in various catalytic oxidation reactions, exist on the mayenite surface.

AB - Finely dispersed calcium aluminate C12A7 (12CaO⋅7Al2O3) samples are synthesized in water and in an autoclave using supercritical drying. The specific surface area of the aerogel samples reaches 330 m2/g immediately after drying in an autoclave and 170 m2/g after calcination at 500°C. Nanocrystalline materials with a mayenite crystal structure and a specific surface area of about 80 m2/g are obtained after calcination at 600°C in water by the reaction of CaO with an aluminum hydroxide suspension. The supported catalysts containing Pd, V, Fe, Ni, Cu, and Ag are synthesized by incipient wetness impregnation of the C12A7 sample obtained in water. The catalytic activity of the synthesized samples is studied in the oxidation of carbon monoxide CO. The highest catalytic activity is demonstrated by the 1% Pd/C12A7 sample. Electron-acceptor sites capable of ionizing phenothiazine molecules to its radical cations, electron-donor sites ionizing trinitrobenzene to its radical anions, and radical sites reacting with diphenylamine to form stable nitroxyl radicals are observed on the surface of all the synthesized materials based on C12A7. The formation of nitroxide radicals after the adsorption of diphenylamine indicates that oxygen radicals on the mayenite surface, which can be highly active in various catalytic oxidation reactions, exist on the mayenite surface.

KW - active sites

KW - aerogels

KW - calcium aluminate

KW - CO oxidation

KW - EPR

KW - mayenite

KW - nanosized oxides

UR - http://www.scopus.com/inward/record.url?scp=85135963874&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/96a37770-5aab-39eb-a503-f2dc0fe2365d/

U2 - 10.1134/S199079312203023X

DO - 10.1134/S199079312203023X

M3 - Article

AN - SCOPUS:85135963874

VL - 16

SP - 411

EP - 420

JO - Russian Journal of Physical Chemistry B

JF - Russian Journal of Physical Chemistry B

SN - 1990-7931

IS - 3

ER -