Showing papers by "Francisco Rodríguez-Reinoso published in 2000"

Sciences of carbon materials

Abstract: Sciences which are used to understand the properties and applications of carbons and graphites need to be described, comprehensively, in book format, at an up-to-date and introductory level. This book introduces the reader, comprehensively, to the sciences of structure of carbons, applications of carbon in nuclear energy, the chemistry of pitch carbonization, the spinnig of carbon fibres, carbon gasification reactions and oxidation protection, mechacnical properties, porosity and adsorption in carbons and coals, with chapters describing coal carbonization, coal liquefaction and the petrography of coal. The book serves both as a textbook and as a reference book and as a text for courses within educational institutions, worldwide.

Crotonaldehyde hydrogenation over alumina- and silica-supported Pt-Sn catalysts of different composition. In situ DRIFT study

Abstract: Alumina- and silica-supported bimetallic Pt–Sn catalysts with different Pt/Sn atomic ratios have been prepared by using the bimetallic complex cis-[PtCl(SnCl3)(PPh3)2], the monometallic complex cis-[PtCl2(PPh3)2] and SnCl2 as metal precursors. Catalysts have been characterised by X-ray diffraction and transmission electron microscopy techniques, including energy-dispersive X-ray microanalysis, electron diffraction experiments and lattice-fringe microanalysis. The phase composition of the different catalysts has been related to the catalytic behaviour in the vapour phase hydrogenation of crotonaldehyde (but-2-enal). Results show that catalysts containing platinum–tin alloy phases with large particles are more selective towards the hydrogenation of the carbonyl bond to yield crotyl alcohol. The presence of oxidised tin species on the surface of the large alloy particles promotes the hydrogenation of the carbonyl bond. In situ diffuse reflectance infrared spectroscopy studies of crotonaldehyde adsorption under He or H2 reveal differences between bimetallic catalysts and monometallic, and these differences have been related to the different catalytic behaviour of the catalysts.

Preparation and characterization of carbon-supported Pt-CeO2 catalysts

Abstract: Activated carbon-supported cerium dioxide (CeO2/C) has been prepared by impregnation of the support with a solution of cerium (III) nitrate and further decomposition in helium. Then, platinum has been deposited on CeO2/C by impregnation with solutions containing H2PtC16 or [Pt(NH3)4](NO3)2. Sample characterisation has been carried out by thermogravimetry (TG), temperature-programmed decomposition (TPD) and reduction (TPR), X-Ray diffraction and temperature-programmed desorption of adsorbed hydrogen (H2-TPD). The interaction between cerium oxide and platinum after different reduction treatments has been checked in two test reactions carried out in the gas phase: hydrogenation of benzene and hydrogenation of crotonaldehyde (2-butenal). Results show that ceria is very well dispersed on the carbon support, this enhancing its interaction with the active metal after high temperature reduction treatments (773 K).

Synthesis of a (MoSi2, Mo5Si3)/SiC composite using an in situ solid-state displacement reaction between Mo2C and Si

Abstract: The intermetallic compound, MoSi2, has great potential as an elevated-temperature structural material but it exhibits some undesirable properties such as low fracture toughness and low strength at elevated temperatures. Improvement of these properties can be achieved by reinforcing MoSi2 with the addition of SiC particles or whiskers, or by alloying it with Mo5Si3. The preparation of MoSi2 composites from powders gives rise to an oxidation problem since SiO2 covers the raw powder. To avoid this problem, the material must be prepared in situ. In this work, multiphase composites based on the Mo-Si-C system have been prepared using a solid-state displacement reaction between Mo2C and Si. Samples were prepared from a mixture, containing different proportions of Si and Mo2C powders, which was pelletized under vacuum at 40MPa and heat-treated in argon. The pieces obtained exhibit different proportions of SiC, MoSi2 and Mo5Si3. The microhardness obtained ranges from 12 to 14GPa, and Kc is over 8MPa·m1/2, which is higher than that of pieces made of MoSi2 only.