Synthesis of C12A7 calcium aluminate aerogels

Ilyina, Ekaterina V.; Gerus, Yuri Y.; Cherepanova, Svetlana V.; Bedilo, Alexander F.

doi:10.1016/j.matlet.2021.129699

Cited by 12 publications

(14 citation statements)

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“…Figure 3 c shows the EPR spectra observed after DPA adsorption on the samples under study. In this case, the A zz parameter is 16 G. Such spectra were described recently [ 26 , 27 ]. It is worth noting that the triplet in these spectra, which is related to surface diphenyl nitroxide radicals [ 26 ], testifies to the presence of active O − or peroxyl radicals on the surface of the Pd-containing samples.…”

Section: Resultsmentioning

confidence: 82%

“…In this case, the A zz parameter is 16 G. Such spectra were described recently [ 26 , 27 ]. It is worth noting that the triplet in these spectra, which is related to surface diphenyl nitroxide radicals [ 26 ], testifies to the presence of active O − or peroxyl radicals on the surface of the Pd-containing samples. Again, the concentration of radical species for the Pd@C12A7 sample exceeded that for the Pd/C12A7 sample by a factor of ca.…”

Section: Resultsmentioning

confidence: 82%

“…The phase composition of aerogel-prepared mayenite has been studied and reported previously [ 26 , 27 ]. It should be mentioned that, when a stoichiometric amount of water was used, the mayenite phase was amorphous to X-rays.…”

Section: Resultsmentioning

confidence: 99%

“…The mayenite sample was prepared as described elsewhere [ 26 , 27 , 59 ]. In order to synthesize an aerogel with a composition of 12CaO-7Al 2 O 3 (labeled C12A7), the sol-gel method involving a supercritical drying procedure was used.…”

Section: Methodsmentioning

confidence: 99%

“…This method is of considerable interest because it avoids the collapse of the porous structure of the synthesized sample by removing the solvent under supercritical conditions in an autoclave [ 23 , 24 , 25 ]. Recently, we synthesized aerogels of calcium aluminate with a mayenite stoichiometry for the time first [ 26 ]. The specific surface area of such samples reached 170 m 2 /g after calcination at 500 °C.…”

Section: Introductionmentioning

confidence: 99%

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Comparative Study of Pd-Mayenite Catalysts Prepared via Aerogel Approaches

Ilyina

Bedilo

Veselov

et al. 2022

Gels

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Pd-containing catalysts based on highly dispersed aerogel-derived mayenite were prepared via two approaches. The Pd@C12A7 sample was obtained through the addition of Pd nitrate solution to a fresh Ca(OH)2-Al(OH)3 gel. Pd/C12A7 was synthesized through conventional wet impregnation of the aerogel-derived mayenite. The evolution of the textural characteristics of the support (C12A7) depending on the calcination temperature was investigated. Pd-containing samples were explored using transmission electron microscopy and spin probe EPR spectroscopy. Using the latter method, the presence of active oxygen species capable of producing nitroxyl radicals from diphenylamine was observed. The activity of these species and the reproducibility of their redox behavior were studied in three cycles of temperature-programmed reduction in both hydrogen and CO atmospheres. A prompt thermal aging technique was used to access and compare the activity of the samples towards CO oxidation. The state of Pd species before and after the aging procedure was studied via UV–Vis spectroscopy. It was found that the dispersion of PdO was higher in the case of the Pd/C12A7 catalysts compared to the Pd@C12A7 sample. This is why the Pd/C12A7 catalyst demonstrated higher activity in CO oxidation and better reducibility in TPR cycles.

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Section: Resultsmentioning

confidence: 82%