Reference : Mass transfer in low-density xerogel catalysts

	Document type :	Scientific journals : Article
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Chemistry Engineering, computing & technology : Materials science & engineering Engineering, computing & technology : Chemical engineering
	To cite this reference:	http://hdl.handle.net/2268/20317

Title :	Mass transfer in low-density xerogel catalysts
Language :	English
Author, co-author :	Heinrichs, Benoît [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Chimie physique appliquée > >]
	Pirard, Jean-Paul [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Chimie physique appliquée > >]
	Schoebrechts, Jean-Paul [Solvay S.A. > Laboratoire Central > > >]
Publication date :	2001
Journal title :	AIChE Journal
Publisher :	John Wiley & Sons, Inc
Volume :	47
Issue/season :	8
Pages :	1866-1873
Peer reviewed :	Yes (verified by ORBi)
Audience :	International
ISSN :	0001-1541
City :	Hoboken
Country :	NJ
Abstract :	[en] Texture and morphology of a Pd-Ag/SiO2 hydrodechlorination low-density xerogel catalyst prepared by a cogelation sot-gel process were characterized in detail to examine mass transfer in such catalysts. The catalyst consists of active Pd-Ag nanocrystallites trapped inside elementary 20 nm microporous silica particles arranged in larger aggregates, which constitute the macroscopic pellet. To reach active sites, reactants must first diffuse through large pores located between aggregates of SiO2 Particles and then through smaller pores located between those elementary particles inside the aggregates. Finally, they, diffuse through micropores located inside silica particles. Diffusion in such a "funnel" structure cannot be described assimilating the pellet to a pseudo-continuum. Diffusion should be examined carefully at three levels of decreasing size: the macroscopic pellet, the aggregate of silica particles, and the elementary silica particle. This approach shows that cogelled xerogel catalysts have remarkable mass-transfer properties.
Permalink :	http://hdl.handle.net/2268/20317

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