The parallel dehydrative and dehydrogenative catalytic action of gamma-Al2O3 pure and doped by MgO kinetics, selectivity, time dependence of catalytic behaviour, mechanisms and interpretations

Patermarakis, G

dc.contributor.author	Patermarakis, G	en
dc.date.accessioned	2014-03-01T01:53:14Z
dc.date.available	2014-03-01T01:53:14Z
dc.date.issued	2003	en
dc.identifier.issn	0926-860X	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/26894
dc.subject	gamma-Al2O3 + (0 and 1% MgO)	en
dc.subject	formic acid decomposition	en
dc.subject	dehydration	en
dc.subject	dehydrogenation	en
dc.subject	reactions kinetics	en
dc.subject	selectivity	en
dc.subject	mechanisms	en
dc.subject	temperature dependence of ageing and activation	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.classification	Environmental Sciences	en
dc.subject.other	ANODIC AL2O3 FILMS	en
dc.subject.other	FORMIC-ACID	en
dc.subject.other	METAL-OXIDES	en
dc.subject.other	ALUMINA	en
dc.subject.other	DECOMPOSITION	en
dc.subject.other	ADSORPTION	en
dc.subject.other	SILICA	en
dc.subject.other	WATER	en
dc.subject.other	PORES	en
dc.title	The parallel dehydrative and dehydrogenative catalytic action of gamma-Al2O3 pure and doped by MgO kinetics, selectivity, time dependence of catalytic behaviour, mechanisms and interpretations	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	The catalytic test reaction of HCOOH decomposition on pure gamma-Al2O3 and doped (+ MgO (1% w/w)) was studied at temperatures 275-400degreesC. A double dehydrative and dehydrogenative, instead the thought single dehydrative, behaviour of gamma-Al2O3 was disclosed. The dehydration activity is higher for pure alumina and decreases with operation time while the dehydrogenation activity is higher for doped and increases with time at the higher but decreases at the lower temperatures showing an unusual temperature dependent activation and ageing. Doping and increase of temperature reduce dehydration selectivity. It decreases with operation time at higher but increases at lower temperatures. The Arrhenius kinetic parameters of reactions differ strongly. Activation energy of dehydration seems unaffected and pre-exponential factor slightly affected by catalyst kind and operation time. Parameters concerning dehydrogenation are affected slightly by catalyst kind and strongly by operation time. Based on an atomic scale structure analysis and results, two dehydration and one dehydrogenation coexisting mechanisms stemming from identical initial step of dissociative adsorption of HCOOH as H+ and HCOO- were suggested interpreting the results. The observed behaviour is due to changes of surface atomic spacing by doping Mg2+ and of mean distances of adsorptive pair sites with operation time caused by the second mechanism. (C) 2003 Elsevier B.V. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	APPLIED CATALYSIS A-GENERAL	en
dc.identifier.isi	ISI:000186140800002	en
dc.identifier.volume	252	en
dc.identifier.issue	2	en
dc.identifier.spage	231	en
dc.identifier.epage	241	en