Titania catalyst preparation

Vanadia on titania catalysts prepared by wet impregnation (ammonium metavanadate) and monolayer catalysts prepared by grafting using vanadyl acetylacet-onate were compared [20]. It was demonstrated that monolayer catalysts show better activities at similar vanadium loadings than those of commercial catalysts. 

Slamet Nasution, H. W. Pumama, E. Kosela, S. Gunlazuardi, J. Photocatalytic reduction of C02 on copper-doped titania catalysts prepared by improved-impregnation method. Catal. Commun., 2005,6,313-319. 

Keywords titania, catalysts preparation, inteifacial chemistiy, adsorption... 

For Ti02 and Z1O2, it is well known that sulfation induces a strong increase of acidity [17] and the participation of an add mechanism could then account for this promotion of activity. This mechamsm can be described as a bifunctional process oxidation of NO to NO on Cu sites, and nitration of a product of the oxidation of decane on the acid fiinction(8). The preparation of the catalyst must have a great influence on the activity. This has been shown by the comparison of three Cu/TiC catalysts prepared in different conditions one in which titania is first treated with sulfuric acid, then by Cu acetate (denominated Cu 04/Ti02, containing 0.S wt% Cu, 0.6 wt% S), one in which Cu is... 

The reduction of the catalyst precursor with sodium formate resulted in a lower Pd dispersion than the catalyst prepared by hydrogen reduction, the particle size is much larger in the former catalyst. The mesoporous carbon supported Pd catalysts are near to those of Pd on titania with respect to their enantiodifferentiating ability. Besides the metal dispersion, the availability of the Pd surface in the pores for the large modifier molecules seems to be the determining factor of the enantioselectivity. 

This review will examine some of the methods for the preparation of nanostructured titania catalysts with controlled phase and architecture. Specifically, analyses quasi-... 

The present paper focuses on the interactions between iron and titania for samples prepared via the thermal decomposition of iron pentacarbonyl. (The results of ammonia synthesis studies over these samples have been reported elsewhere (4).) Since it has been reported that standard impregnation techniques cannot be used to prepare highly dispersed iron on titania (4), the use of iron carbonyl decomposition provides a potentially important catalyst preparation route. Studies of the decomposition process as a function of temperature are pertinent to the genesis of such Fe/Ti02 catalysts. For example, these studies are necessary to determine the state and dispersion of iron after the various activation or pretreatment steps. Moreover, such studies are required to understand the catalytic and adsorptive properties of these materials after partial decomposition, complete decarbonylation or hydrogen reduction. In short, Mossbauer spectroscopy was used in this study to monitor the state of iron in catalysts prepared by the decomposition of iron carbonyl. Complementary information about the amount of carbon monoxide associated with iron was provided by volumetric measurements. 

Fig. 3 Results for the photocatalytic reduction of nitrate in the presence of 0.04 M HCOOH as hole scavenger over titania and Ag/Ti02 catalysts prepared by impregnation (IMP) or photodeposition (Photo) and comparing use of Degussa P25 (49 m g ) with Hombikat UV 100 (250 m g ) as supports. ...

This work was supported by "JUNTA DE ANDALUCIA" (Res. SEPT.88). One of us (M.G.G.) wishes to thank the Ministry of Education and Science of Spain for the award of a scholarship.Authors are very gratefull to Mr. F.J.Marchena (Universi ty of Sevilla,Spain) for the preparation of iron-doped titania catalysts. Fina lly, we are gratefull to Dr. Pierre Pichat (CNRS.Ecole Centrale de Lyon,France) for helpful discussions and continuing collaboration on this and related photo catalytic transformations. 

Tanaka et al. [73] developed another MEMS system for the catalytic combustion of butane. It is composed of a combustion chamber 8 mm wide, 14 mm long and 150 pm deep which was prepared by anisotropic wet etching of a silicon substrate. The substrate was then covered with Pyrex glass applying anodic bonding. Combustion was performed on a platinum/titania catalyst... 

For different electrochemical applications such as batteries, supercapacitors, fuel elements porous carbon nanomaterials are used. We have obtained porous carbon nanofibers by CVD method from acetylene with use of new (Fe,Co,Sn)/C/Al203-Si02 catalysts prepared by mechanochemical method [13, 14]. The porous nanostructures formed (Fig. 4) somewhat resembles structures, synthesized in [15] on titania-containing catalyst. 

Figure 4.3 Gold loading and yield of DP versus solution pH for Au/Ti02 (Degussa P-25) catalysts prepared by DP (titania added to the NaOH solution, preparation at 343K, nominal Au loading lwt.%).67...

Isopova ct al. described the preparation of various perovskite-based monolithic catalysts for fuel combustion by extrusion of synthesized perovskite powders [14]. Blanco ct al. [25], Lachman and Williams [97], and del Valle et al. [98] reported titania-based and other monolithic catalysts by extrusion. The titania catalysts were tested in a coal-fired power pilot plant for electrostatic separation of fly-ash [98]. Lyakhova et al. studied the W03-doped titania-vanadia monolithic catalysis for selective catalytic reduction (SCR NOx conversion) by extrusion [26]. The rheological properties of the paste for extrusion and the effect of various organic plastisizers on catalytic activity in SCR were discussed. 

Santos J, Phillips J, Dumesic J (1983) Metal support interactions between iron and titania for catalysts prepared by thermal-decomposition of iron pentacarbonyl and by impregnation. J Catal 84 147... 

Supported Palladium. - For catalysts prepared by impregnation with PdQ2 on silica, titania, and alumina supports and reduced (673 K), the width of the Pd 3c 5/2 lines in the photoelectron spectra was greater than the value for unsupported palladium and decreased in the order... 

F. Moreau, G. C. Bond, A. O. Taylor, Gold on titania catalysts for the oxidation of carbon monoxide Control of pH during preparation with various gold contents, ]. Catal. 231 (2005) 105. 

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