Niobium-containing hydroxyapatites as amphoteric catalysts: synthesis, properties, and activity
Articolo
Data di Pubblicazione:
2014
Citazione:
Niobium-containing hydroxyapatites as amphoteric catalysts: synthesis, properties, and activity / P. Carniti, A. Gervasini, C. Tiozzo, M. Guidotti. - In: ACS CATALYSIS. - ISSN 2155-5435. - 4:2(2014 Jan), pp. 469-479.
Abstract:
We present here a new class of Nb-containing catalysts
offering both acid and base functionalities thanks to the hydroxyapatite
(HAP) structure, which acts as a host matrix for guest niobium species.
Incorporation of Nb has led to samples with strengthened amphoteric
properties with a prevalence of acid or basic sites depending on the synthesis
procedure. Nb-containing HAP samples (12−14 wt % of Nb) have been
synthesized by coprecipitation in water and in alcoholic solutions and by
impregnation starting from different precursors. The intrinsic and effective
acid and base properties have been measured, and a series of mass and
surface characterizations have been performed to determine the Nb content,
its oxidation state as well as its morphologic, structural, and electronic
properties. The performances of the samples have been studied in several
reactions of liquid−solid heterogeneous catalysis in batch or fixed tubular
reactors working in the recirculation mode on the basis of the known catalytic features of Nb, including hydrolysis, acid-catalyzed
isomerization, and selective oxidation reactions.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
calcium hydroxyapatite ; niobium catalysts ; solid acidity ; solid basicity ; amphoteric properties of catalysts ; oxidation reactions ; saccharide conversion
Elenco autori:
P. Carniti, A. Gervasini, C. Tiozzo, M. Guidotti
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