TY - JOUR

T1 - Mayenite Synthesis from Hydroxide Precursors: Structure Formation and Active Sites on Its Surface

AU - Kapishnikov, Aleksandr V.

AU - Kenzhin, Roman M.

AU - Koskin, Anton P.

AU - Volodin, Alexander M.

AU - Geydt, Pavel V.

N1 - Funding Information: Funding: This work was supported by the Ministry of Science and Higher Education of Russian Federation by the grant . Funding Information: This work was supported by the Ministry of Science and Higher Education of Russian Federation by the grant FSUS-2020-0029. The authors are thankful to A.O. Geydt for help with translation. The authors acknowledge the Center of Collective Use ?VTAN? of NSU for the usage of the XRD equipment. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2022/2/1

Y1 - 2022/2/1

N2 - We studied the formation process of a mayenite structure from hydroxide precursors in different gas media. According to X-ray diffraction data, this method allows a well-crystallized mayenite (Ca12 Al14 O33 or C12A7) phase to be obtained at low (500–900◦ C) temperatures with an insignificant impurity of CaO. It was shown that the lattice parameters for C12A7 obtained in an inert atmosphere (Ar) were lower when compared with similar samples in the air. These results can be explained by the different levels of oxygen nonstoichiometry in the resulting phase. We noted that sintering and crystallization of mayenite proceeds at lower temperatures in Ar than in the air medium. We found the presence of donor and acceptor active sites on the surface of mayenite, which was detected by the spin probe method. The specific (per unit surface) concentration of such sites (2.5 × 1016 m−2 and 1.5 × 1015 m−2 for donor and acceptor sites, respectively) is comparable to that of γ-Al2 O3, which is traditionally used as catalyst support. This allows it to be used in adsorption and catalytic technologies, taking into account its high specific surface area (~30–50 m2 /g at a low synthesis temperature).

AB - We studied the formation process of a mayenite structure from hydroxide precursors in different gas media. According to X-ray diffraction data, this method allows a well-crystallized mayenite (Ca12 Al14 O33 or C12A7) phase to be obtained at low (500–900◦ C) temperatures with an insignificant impurity of CaO. It was shown that the lattice parameters for C12A7 obtained in an inert atmosphere (Ar) were lower when compared with similar samples in the air. These results can be explained by the different levels of oxygen nonstoichiometry in the resulting phase. We noted that sintering and crystallization of mayenite proceeds at lower temperatures in Ar than in the air medium. We found the presence of donor and acceptor active sites on the surface of mayenite, which was detected by the spin probe method. The specific (per unit surface) concentration of such sites (2.5 × 1016 m−2 and 1.5 × 1015 m−2 for donor and acceptor sites, respectively) is comparable to that of γ-Al2 O3, which is traditionally used as catalyst support. This allows it to be used in adsorption and catalytic technologies, taking into account its high specific surface area (~30–50 m2 /g at a low synthesis temperature).

KW - Catalytic materials

KW - Mayenite

KW - Spin probe method

KW - Surface active sites

KW - XRD

UR - http://www.scopus.com/inward/record.url?scp=85123093421&partnerID=8YFLogxK

U2 - 10.3390/ma15030778

DO - 10.3390/ma15030778

M3 - Article

C2 - 35160729

AN - SCOPUS:85123093421

VL - 15

JO - Materials

JF - Materials

SN - 1996-1944

IS - 3

M1 - 778

ER -