from first principles PP-I-1

PP-III-75Influence of the ZrO 2 Phase Composition, Steady-state Y 2 O 3on CO Oxidation on Supported Palladium CatalystsMovchan B.A. 1 , Didikin G.G. 1 , Romanenko S.M. 1 , Oranska O.I. 3 , Zaitsev Yu.P. 21 The E.O.Paton Electric Welding Institute NAS Ukraine, Kiev, Ukraine2 Institute for Sorption and Endoecology Problems NAS Ukraine, Kiev, Ukraine3 Institute of Surface Chemistry A.Chuyko NAS of Ukraine, Kiev, Ukrainezaitsev@ispe.kiev.uaIn this paper we give study of the influence of phase composition - ZrO 2 -Y 2 O 3 , derived usingEB-PVD method, on physico-chemical properties and catalytic activity of supportedpalladium compounds in the CO oxidationX-ray amorphous ZrO 2 - 6,5%Y 2 O 3 consists of superfine randomly oriented crystallites, which sizeis 3-5 nm. The samples, that contain 9,5% and 15%Y 2 O 3 are cubic ZrO 2(JCPDS № 81-1550), with average crystallite size, calculated to Scherrer equation 14 and 18 nm.Palladium was supported by impregnation with Pd(NO 3 ) 2 solution and additional recoverywith formaldehyde. In the case of amorphous sample, Pd is mainly situated in meso- andmacropores, and in crystallic samples significant amount of Pd is situated in micropores. Suchdependencies are also observed in the samples, that were used in catalysis.100Конверсия СО, %8060402000 50 100 150Температура, оС123Fig. 1. Dependence samples catalytic activity on thetemperature in the reaction of CO oxidation:1 - ZrO 2 -6,5%Y 2 O 3 +1% Pd, 2 - ZrO 2 -9,5%Y 2 O 3 +1% Pd,3 - ZrO 2 -15%Y 2 O 3 +1% PdThe plot of temperature dependence of catalytical activity (fig. 1) can be roughly divided intotwo domains. First is domain of transient activity (up to a temperature 120°C) and II - theregion of stationary activity - above 120°C. In the first domain, activity was measured after10 min after entering the mode. At the temperatures above 70 o C it decreased over time. Thereason could be enlargement of the palladium particles. Domain of transient activity isobserved in cases of all studied samples, but it is much more in the case of amorphous carrier,probably due to some stabilization of active clusters of finely dispersed Pd. In the second230