ELSEVI ER lnorganica Chimica Acta254 (1997) 37-41 Reaction of triruthenium dodecacarbonyl with high-area rare earth oxides Linda A. Bruce, Manh Hoang, Anthony E. Hughes, Terence W. Turney * CS.LR. 0., Division of Materials Science and Technology. Private Bag 33. Rosebank MDC, Clayton, Vic. 3169. Australia Received 19 September1995; revised16January 1996 Abstract Reaction of Ru3 (CO) 12with high area ( > 45 m2 g- ~ ) oxides of the rare earths, La, Ce, Pr, Tb, He and Yb has been studied by IR and X-ray photoelectron spectroscopy. Evidence is presented for formation of surface species [ (OC)2RB(OM)2]n at ~2C~(wt./wt.) RB loading for all oxides and for a surface cluster, possibly [Ru3(/z-H)(CO)Io(/t-OM)], at 5%(wt./wt.) metal loadings for Ce and He oxides. Keywords: Ruthenium complexes; Rareearth oxidecomplexes 1. Introduction Supported Ru catalysts have been demonstrated to be amongst the most active catalysts for CO hydrogenation showing a high selectivity towards methane production [ 1 ]. It is well known that this selectivity towards methane pro- duction is strongly influenced by the nature of the support. For example, when Ru is dispersed on acidic supports such as Al203 the product distribution favours higher molecular weight hydrocarbons, whereas methane production is fa- voured on unsupported Ru or Ru supported the more basic oxides [ 1-3]. Furthermore, the Ru crystallite size plays an important role in product selectivity [ 4]. Traditional methods of impregnation, such as incipient wetness techniques, can give Ru crystallite sizes which are very dependent on solution conditions, particularly pH [5]. In addition, this type of impregnation can often result in co- adsorption of anions such as chloride or nitrate from the Ru- salt used to prepare the solution. Deposition of metal carbonyl clusters onto .~xide supports can, in principle, produce a cat- alyst which is I~'h finely divided and monodispersed with respect to the metal crystallites [6]. Previous studies of the adsorption of Ru3(CO) 12onto and reaction with various oxides have provided evidence for a range of surface species which depends on the acidity of the support and treatment conditions. Hence Ru3(CO)12 is reported to react with surface hydroxyl groups to produce species of the type [(OC)2Ru(OM)2]n (l) [7-11], [Ru3H(CO)H ]- (2) [7,11-13], [Ru3(p,-H)(CO)lo(p,- *Corresponding author. Fax: +61 (3) 9544 !128; e-mail: tumcy@mst.csiro.au. OM)] (3) [11,14-17] and [RutC(CO)lt] 3- (4) [10,18] depending on the nature of the support and deposition conditions. Recently, a method has been reported for the preparation of high surface area rare earth oxides [ 19,20]. The adsorption of Ru3 (CO) t2 onto these high surface area oxides provides a prospect for novel catalysts ,#ith high metal dispersion for Fischer-Tropsch synthesis. "I i-dswork examines the reaction of Ru3(CO) 12 with these hig : surface area rare earth oxides. S~bsequent reports will adi~ ess the reduction of the surface carbonyls, the interaction of~ese Ru/REO systems with CO, CO2 and H 2 and their Fischer-Tropsch performance. 2. Experimeatal 2.1. Materials Syntheses and characterisation of high area La203 (54 m e g- i), Ho203 (60 m 2 g- ' ), Yb203 (45 m 2 g- l), CeO2 ( 170 m2 g- '),Pr6OH (80m2 g -l) and Tb40. I (53 m2 g -l) pow- ders are reported elsewhere [ 19,20]. Although air-exposure during synthesis and handling was minimised, surface car- bonate was identified by IR on each suppori except CeO2 prior to Ru adsorption. XPS analysis of the La2.03 support similarly showed carbonate contamination. Adsorption of Ru3(CO)12 on each of the rare earth oxides (freshly calcined at 600 °C) was carried out in n-heptane solution ( 1.0 g I - ! conc.) with stirring under N2 (21 0(2, 16 h). Ruthenium metal loadings were varied between 1- 5% (wt./we.) by altering solution volumes. The resultant sol- ids were filtered and washed with pure n-heptane before 0020-1693/97/$17.00Copyright © 1997Elsevier Science S.A.Allrights reserved PII S0020-1693 (96) 05132-8