Supported palladium reactivity

The Effect of Particle Size on the Reactivity of Supported Palladium... 

Hayden BE (1997) The structure and reactivity of Ti02 (110) supported palladium and rhodium. In Lambert RM, Pacchioni G (eds) Chemisorption and reactivity on supported clusters and thin films. Kluwer Academic Publishers, Norwell, p 215... 

Bozon-Verduraz F, Omar A, Escard J, Pontvianne B. Chemical state and reactivity of supported palladium I. characterization by XPS and UV-visible spectroscopy. J Catal. 1978 53 126-134. 

Carrasco-Marm F, Solar JM, Radovic LR. On the importance of electrokmetic properties of carbon for the gasification reactivity of carbon-supported palladium catalysts. International Carbon Conference (Paris). 1990, pp. 672-673. 

Due to the particular importance of supported palladium catalysts [198-200], we performed additional studies of the model clusters Pd4 and Pds on MgO(OOl) [175,176] and of CO molecule adsorption on these deposited model systems [176]. These studies aimed at a more thorough elucidation of the changes in the electronic structure and reactivity of the clusters induced by interactions with the MgO(OOl) substrate. 

In this paper we will report on the selective hydrogenation of o /3 unsaturated aldehydes using a supported palladium catalyst in a range of ionic liquids. We will also compare their reactivity and selectivity to conventionally used organic solvents. Two systems have been investigated, cinnamaldehyde to form hydrocinnamaldehyde and citral... 

Recently, palladium complexes of carbene ligands have been recognized as highly reactive catalysts for palladium-promoted reactions, in particular for the Heck reaction [42-44]. The polymer-supported palladium carbene complexes 18 and 19 were prepared by the nucleophilic substitution of the bromomethy-lated Wang resin with 17 under basic reaction conditions (Scheme 7) [45]. The catalytic activity of 18 and 19 was examined for the Heck reaction of aryl bromides with acrylates or styrene to exhibit high TONs up to 5,000. The polymer-supported palladium-carbene complexes are air-stable and recyclable. 

Highly active immobilized palladium catalysts modified with a rigid C,N,C-pincer carbene ligand were successfully applied in the coupling of aryl halides to terminal acetylenes. The homogeneous catalyst was immobilized on three types of solids - montmorillonite K-10, bentonite A, and bentonite B - by the solvent-impregnation method. No significant differences were observed in the catalytic efficiency between the various supports. The reactivity of the system is relatively constant after as many as five cycles [68]. 

Yang, S., Maroto-Valiente, A., Benito-Gonzalez, M., Rodriguez-Ramos, I. Guer-rero-Ruiz, A. Methane combustion over supported palladium catalysts I. Reactivity and active phase. Applied Catalysis B Environmental 28, 223-233 (2000). Vaarkamp, M., Modica F. S., Miller J. T. Koningsberger D. C. Influence of hydrogen pretreatment on the structure of the metal-support interface in Pt/zeoUte catalysts. Journal of Catalysis 144, 611-626 (1993). 

The supported palladium catalyst known to be the most active for total methane oxidation was the subject of considerable amount of research [1-9]. However, no agreement about the mechanism reaction was observed in the literature [1-8]. The Langmulr-Hinshelwood [1-4], the Eley-Rideal [5-7], and the Mars-Van Krevelen [8], mechanisms were proposed for the total oxidation of methane on the supported palladium catalysts. This diversity is explained by the variation of the active surface in each case. Indeed, according to Burch et al.[9], the active sites can be modified by the pre-treatment conditions, by the particle size, by the support nature and by the presence of some poisons such as chlorides. Others difficulties result from the fact that it is not confirmed if the active site is a partial or a total oxidized palladium particle. In addition, little is known about the reactive oxygen form. Indeed, it is not yet established if the reactive oxygen is a chemisorbed molecular or ionic form or a lattice oxygen ion. The aim of this paper is to identify the palladium oxidation state under catalytic stream, to study the reactive form of oxygen and to propose a mechanism of the reaction. 

Specehia, S., Finocchio, E., Busca, G., et al. (2009). Surface ehemisiry and reactivity of ceria—zirconia-supported palladium oxide eatalysts for natural gas eombustion, J. Catal., 263, pp. 134-145. 

Busca, G. and Finocchio, E. (2011). Surface science and industrial catalysis Redox states of alumina supported palladium nanoparticles. La Chimica e I Industria, 93, pp. 85-95. Montanari, T., Marie, O., Daturi, M., et al. (2005). Cobalt on and in zeolites and silica-alumina Spectroscopic characterization and reactivity, Catal. Today, 110, pp. 339-344. 

As catalyst for the Rosenmund reaction palladium on a support, e.g. palladium on barium sulfate, is most often used. The palladium has to be made less active in order to avoid further reduction of the aldehyde to the corresponding alcohol. Such a poisoned catalyst is obtained for example by the addition of quinoline and sulfur. Recent reports state that the reactivity of the catalyst is determined by the morphology of the palladium surface." ... 

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