Effect of synthesis parameters on precipitation of nanocrystalline boehmite from aluminate solutions

Panias, D; Krestou, A

dc.contributor.author	Panias, D	en
dc.contributor.author	Krestou, A	en
dc.date.accessioned	2014-03-01T01:26:12Z
dc.date.available	2014-03-01T01:26:12Z
dc.date.issued	2007	en
dc.identifier.issn	0032-5910	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/17968
dc.subject	Boehmite	en
dc.subject	Nanocrystalline	en
dc.subject	Neutralization	en
dc.subject	Precipitation	en
dc.subject.classification	Engineering, Chemical	en
dc.subject.other	Adsorbents	en
dc.subject.other	Alumina	en
dc.subject.other	Concentration (process)	en
dc.subject.other	pH effects	en
dc.subject.other	Precipitation (chemical)	en
dc.subject.other	Synthesis (chemical)	en
dc.subject.other	Boehmite	en
dc.subject.other	Neutralization	en
dc.subject.other	Precipitated phases	en
dc.subject.other	Nanocrystalline materials	en
dc.subject.other	aluminum oxide	en
dc.subject.other	Adsorbents	en
dc.subject.other	Alumina	en
dc.subject.other	Concentration (process)	en
dc.subject.other	Nanocrystalline materials	en
dc.subject.other	pH effects	en
dc.subject.other	Precipitation (chemical)	en
dc.subject.other	Synthesis (chemical)	en
dc.subject.other	article	en
dc.subject.other	crystallization	en
dc.subject.other	high temperature	en
dc.subject.other	morphology	en
dc.subject.other	pH	en
dc.subject.other	precipitation	en
dc.subject.other	synthesis	en
dc.title	Effect of synthesis parameters on precipitation of nanocrystalline boehmite from aluminate solutions	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.powtec.2007.01.028	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.powtec.2007.01.028	en
heal.language	English	en
heal.publicationDate	2007	en
heal.abstract	Nanocrystalline boehmite (gamma-AlOOH) is a cost-effective material for the production of gamma-Al2O3 finding many industrial applications as catalyst or catalyst support, membranes and adsorbents. The preparation conditions applied in the production step of nanocrystalline boehmite strongly affect its morphology, which in turn is reflected to the final transition alumina. In this work, a precipitation method for the production of nanocrystalline boehmite is described studying the effect of pH, temperature and ageing time on the morphology of the final precipitate. The experiments were performed at temperatures 30, 60 and 90 degrees C, under moderate pH conditions (5, 6, 7) and 1 week of ageing in the mother liquor. What are noteworthy in the performed experiments are the starting solution used and the mixing procedure. The starting solution was a supersaturated sodium aluminate solution (SSA) with concentration equal to the Bayer liquor, which is not usually used in such synthesis experiments. On the other hand, the mixing procedure did not follow the usual route of addition of the neutralization agent (acid) to the SSA solution; on the contrary the SSA solution was added to the neutralization agent. Amorphous boehmite was prepared at temperatures as low as 30 degrees C and pH 7 under prolonged ageing conditions. At 60 degrees C the formation of pure nanocrystalline boehmite with crystallites 3-8 nm, was facilitated at pH 6 and pH 7 after ageing in the mother liquor, while at the higher temperature of 90 'C the formation of pure nanocrystalline boehmite with crystallite size between 3 and 13 nm was achieved at pH 5, pH 6 and pH 7. Ageing and temperature influenced the crystallinity of the precipitated phases, with prolonged ageing and high temperatures inducing high crystallinity. The pH conditions also had a strong effect on the crystallite size of precipitates. Actually, for the same temperature and ageing time the higher the pH the larger the crystallites of the precipitates. (c) 2007 Elsevier B.V All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE SA	en
heal.journalName	Powder Technology	en
dc.identifier.doi	10.1016/j.powtec.2007.01.028	en
dc.identifier.isi	ISI:000247415100006	en
dc.identifier.volume	175	en
dc.identifier.issue	3	en
dc.identifier.spage	163	en
dc.identifier.epage	173	en