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Physico-Chemical Properties of MgGa Mixed Oxides and Reconstructed Layered Double Hydroxides and Their Performance in Aldol Condensation of Furfural and Acetone

Rok: 2018

Druh publikace: článek v odborném periodiku

Název zdroje: Frontiers in chemistry

Název nakladatele: FRONTIERS MEDIA SA

Místo vydání: Lausanne

Strana od-do: "176-1"-"176-17"

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
cze	Fyzikálně chemické vlastnosti MgGa směsných oxidů a rekonstruovaných vrstevnatých podvojných hydroxidů a jejich výkonnost v aldolové kondenzaci furfuralu a acetonu	MgGa vrstevnaté podvojné hydroxidy (Mg/Ga = 2-4) byly syntetizovány a použity pro přípravuy MgGa směsných oxidů a hydrotalcitů. Vlastnosti připravených materiálů byly charakterizovány řadou metod (XRD, TGA, NH3-TPD, CO2-TPD, SEM, and DRIFT) a testovány jako katalyzátory pro aldolovou kondenzaci furfuralu a acetonu.	MgGa podvojné soli; Vrstevnaté hydroxidy; směsné oxidy; hydrotalcity; aldolová kondenzace; acidobazické vlastnosti
eng	Physico-Chemical Properties of MgGa Mixed Oxides and Reconstructed Layered Double Hydroxides and Their Performance in Aldol Condensation of Furfural and Acetone	MgGa layered double hydroxides (Mg/Ga = 2-4) were synthesized and used for the preparation of MgGa mixed oxides and reconstructed hydrotalcites. The properties of the prepared materials were examined by physico-chemical methods (XRD, TGA, NH3-TPD, CO2-TPD, SEM, and DRIFT) and tested in aldol condensation of furfural and acetone The as-prepared phase-pure MgGa samples possessed hydrotalcite structure, and their calcination resulted in mixed oxides with MgO structure with a small admixture phase characterized by a reflection at 2 theta <^> approximate to 36 .0 degrees The interaction of MgGa mixed oxides with pure water resulted in reconstruction of the HTC structure already after 15 s of the rehydration with maximum crystallinity achieved after 60s. TGA-MS experiments proved a substantial decrease in carbonates in all rehydrated samples compared with their as-prepared counterparts This allowed suggesting presence of interlayer hydroxyls in the samples Acido-basic properties of MgGa mixed oxides determined by TPD technique did not correlate with Mg/Ga ratio which was explained by the specific distribution of Ga atoms on the external surface of the samples CO2-TPD method was also used to evaluate the basic properties of the reconstructed MgGa samples In these experiments, an intensive peak at T = 450 degrees C on CO2-TPD curve was attributed to the decomposition of carbonates newly formed by CO2 interaction with interlayer carbonates rather than to CO2 desorption from basic sites Accordingly, CO2-TPD method quantitatively characterized the interlayer hydroxyls only indirectly Furfural conversion on reconstructed MgGa materials was much larger compared with MgGa mixed oxides confirming that Bronsted basic sites in MgGa catalysts, like MgAI catalysts, were active in the reaction Mg/Ga ratio in mixed oxides influenced product selectivity which was explained by the difference in textural properties of the samples In contrast, Mg/Ga ratio in reconstructed catalysts had prac	MgGa layered double hydroxides; mixed oxides; reconstructed hydrotalcites; aldol condensation; acido-basic properties

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