Synthesis of C12A7 calcium aluminate aerogels

Calcium aluminate aerogels with mayenite stoichiometry C12A7 were prepared for the first time. The surface area of amorphous aerogel obtained after hydrolysis with stoichiometric amount of water was about 330 m(2)/g after the supercritical drying and 170 m(2)/g after calcination at 500 degrees C. The latter sample mostly consisted of 10-20 nm amorphous platelets. The mayenite phase was observed after the supercritical drying only if overstoichiometric amount of water was used for hydrolysis. Diphenyloxyl nitroxyl radicals were observed on the surface of calcined C12A7 aerogels after diphenylamine adsorption. Their formation on the surface of the samples calcined at 500 degrees C suggests that mayenite cages capable of stabilizing active forms of oxygen are present on the surface of the amorphous aerogels. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Calcium aluminate aerogels with mayenite stoichiometry C12A7 were prepared for the first time. The surface area of amorphous aerogel obtained after hydrolysis with stoichiometric amount of water was about 330 m(2)/g after supercritical drying and 170 m(2)/g after calcination at 500 degrees C. The presence of diphenyloxyl nitroxyl radicals on the surface of calcined C12A7 aerogels suggests the existence of mayenite cages capable of stabilizing active forms of oxygen.