PARTICIPANT No. 1: UNIVERSITY OF CÁDIZ

1. LABORATORIES
The Research Activities of our Group are developed at the Department of Material Science, Metallurgical Engineering and Inorganic Chemistry of the University of Cádiz (UCA). The Laboratories are settled at the Faculty of Sciences in Puerto Real (Cádiz). Spain.

2. PERSONNEL
Our Group consists of 16 full time researchers including: - 4 Permanent Professors - 4 Doctors under contract with UCA - 8 Doctorate Students.

3. SUMMARY OF ACTIVITIES
Since its creation, 15 years ago, our Group is working on different aspects of the Preparation and Characterization of Rare Earth Oxide based Catalysts. In our studies, conventional characterization techniques as well as High Resolution Electron Microscopy (HREM) are systematically used. Digital processing and computer simulation techniques are routinely applied in the interpretation of the experimental HREM images. At present our major Research Projects deal with ceria based catalysts: CeMO_x (M: Zr, RE), NM/CeO₂ (CeMO_x) (NM: Noble Metals); CeMO_x/Al₂O₃ and NM/CeMO_x/Al₂O₃.

The topics investigated by us include:

• Oxygen Storage Capacity (OSC) Influence of the chemical composition and structural properties of the ceria-based mixed oxides. Influence of the highly dispersed Noble Metal. The role of metal precursors used in the preparation of the NM/CeMOx catalysts.

• Deactivation Mechanisms Operating in NM/CeMO_x Catalysts - Metal-Support Interaction Phenomena: * Electronic Effects * Nanostructural Aspects - Metal Decoration Effects - NM-Ce Alloy Formation - Metal Sintering/Redispersion - Chemical/Textural/Nanostructural Modifications occurred on the mixed oxide supports.

4. SOME PAPERS RECENTLY PUBLISHED BY THE GROUP

• G.A. Martin, S. Bernal, V. Perrichon and C. Mirodatos. HETERO-HOMOGENEOUS PROCESSES INVOLVED IN OXIDATIVE CONVERSION OF METHANE, ETHANE AND HYDROCARBON MIXTURES OVER BASIC OXIDES. Catal. Today 13, 487-494 (1992).
• M. A. Cauqui y J.M. Rodríguez-Izquierdo APPLICATION OF THE SOL-GEL METHODS TO CATALYST PREPARATION J. Non Cryst. Solids, 147 & 148 724-738 (1992)
• M. A. Cauqui, J. J. Calvino, G. Cifredo, L. Esquivias y J. M. Rodríguez-Izquierdo PREPARATION OF RHODIUM CATALYSTS DISPERSED ON TiO2-SiO2 AEROGELS. J. Non Cryst. Solids, 147 & 148 758-763 (1992)
• S. Bernal, F.J. Botana, G. Cifredo, J.J. Calvino, A. Jobacho and J.M. Rodríguez Izquierdo. PREPARATION AND CHARACTERIZATION OF A PRASEODYMIUM OXIDE TO BE USED AS CATALYTIC SUPPORT. J. Alloys and Compounds 180, 271-279 (1992).
• S. Bernal, J.J. Calvino, G.A. Cifredo, J.M. Rodríguez-Izquierdo, V. Perrichon and A. Laachir. THE KEY ROLE OF HIGHLY DISPERSED RHODIUM IN THE CHEMISTRY OF HYDROGEN/CERIA SYSTEM. J. Chem. Soc. Chem. Comm., 460-462 (1992)
• S. Bernal, J.J. Calvino, G.A. Cifredo, J.M. Rodríguez-Izquierdo, V. Perrichon and A. Laachir. REVERSIBILITY OF HYDROGEN CHEMISORPTION ON A CERIA SUPPORTED RHODIUM CATALYST. J. Catal. 137, 1-11 (1992).
• J. Castiglioni, R. Kieffer, F.J. Botana, J.J. Calvino, J.M. Rodríguez-Izquierdo and H. Vidal. CATALYTIC BEHAVIOR AND SURFACE PROPERTIES OF SUPPORTED LANTHANA. J. Alloys and Compounds, 180, 295-301 (1992).
• J.J. Calvino, M.A. Cauqui, G.A. Cifredo, L. Esquivias, J.A. Pérez, M. Ramírez del Solar y J.M. Rodríguez-Izquierdo. ULTRASOUND AS A TOOL FOR THE PREPARATION OF GELS EFFECT ON THE TEXTURAL PROPERTIES OF TiO2-SiO2 AEROGELS. J. Mater. Sci. 28, 2191-2195 (1993)
• S. Bernal, J.J. Calvino, M.A. Cauqui, G.A. Cifredo, A. Jobacho and J.M. Rodríguez-Izquierdo. METAL SUPPORT INTERACTION PHENOMENA IN Rh/CeO2 and Rh/TiO2 CATALYSTS. COMPARATIVE STUDY BY HRTEM. Appl. Catal. 99, 1-8 (1993).
• S. Bernal, F.J. Botana, J.J. Calvino, M.A. Cauqui, G.A. Cifredo, A. Jobacho, J.M. Pintado and J.M. Rodríguez-Izquierdo MICROSTRUCTURAL AND CHEMICAL PROPERTIES OF CERIA SUPPORTED RHODIUM CATALYSTS REDUCED AT 773 K. J. Phys. Chem., 97, 4118-4123 (1993).
• S. Bernal, J.J. Calvino, G.A. Cifredo, J.M. Gatica, J.A. Pérez Omil and J.M. Pintado. HYDROGEN CHEMISORPTION ON CERIA. INFLUENCE OF THE OXIDE SURFACE AREA AND REDUCTION DEGREE. J. Chem. Soc. Faraday Trans. 89, 3499-3505 (1993).
• S. Bernal, F.J. Botana, J.J. Calvino, G.A. Cifredo y J.A. Pérez Omil. HREM STUDY OF THE PHASES RESULTING FROM THE PREPARATION OF CERIA SUPPORTED RHODIUM CATALYSTS. Inst. Phys. Conf. Ser., Vol 138 (Section 10), 485-488 (1993).
• G.A. Cifredo CARACTERIZACIÓN QUÍMICA Y NANOESTRUCTURAL DE CATALIZADORES Rh/CeO2. ESTUDIO PARTICULAR DE LA INTERACCIÓN H2-(Rh/CeO2) Químicos del Sur. 36 11-16 (1993)
• J. J. Calvino, M. A. Cauqui, J. M. Gatica, J. A. Pérez y J. M. Rodríguez-Izquierdo DEVELOPMENT OF ACIDITY ON SOL-GEL PREPARED TiO2-SiO2 CATALYSTS. Better Ceramics Through Chemistry VI, MRS Simposium Proceedings, 346, 685-690 (1994)
• G. Blanco, J. J. Calvino, M. A. Cauqui, G. A. Cifredo ,J. A. Pérez , J. M. Rodríguez-Izquierdo e H. Vidal. CHARACTERIZATION OF SILICA DISPERSED LANTHANA BY CO2 ADSORPTION J. Alloys and Compounds, 207, 201-205 (1994)
• J. J. Calvino, M. A. Cauqui, G. A. Cifredo, J. M. Rodríguez-Izquierdo e H. Vidal. MICROSTRUCTURE AND CATALYTIC PROPERTIES OF Rh AND Ni DISPERSED ON TiO2-SiO2 AEROGELS. J. Sol-Gel Sci. and Technol., 2 , 831-836 (1994)
• S. Bernal, J.J. Calvino, G.A. Cifredo, A. Laachir, V. Perrichon and J.M. Herrmann. INFLUENCE OF THE REDUCTION/EVACUATION CONDITIONS ON THE RATE OF HYDROGEN SPILLOVER ON Rh/CeO2 CATALYSTS. Langmuir 10, 717-722 (1994).
• S. Bernal, J.J. Calvino, G.A. Cifredo, J.M. Gatica, J.A. Pérez Omil, A. Laachir and V. Perrichon. INFLUENCE OF THE NATURE OF THE METAL PRECURSOR SALT ON THE REDOX BEHAVIOUR OF CERIA IN Rh/CeO2 CATALYSTS. Preprints of CAPoC-3 Congress, Vol. 2, p. 275-283; Brussels (1994).
• S. Bernal, G. Blanco, F.J. Botana, J.M. Gatica, J.A. Pérez Omil, J.M. Pintado, J.M. Rodríguez-Izquierdo, P. Maestro and J.J. Braconnier STUDY OF THE REDUCTION/REOXIDATION CYCLE IN A La/Ce/Tb MIXED OXIDE. J. Alloys and Compounds 207/208 (1994)
• S. Bernal, G. Blanco, J.J. Calvino, G.A., Cifredo, J.A. Pérez Omil, J.M. Pintado and A. Varo HRTEM AND TPO STUDY OF THE BEHAVIOUR UNDER OXIDIZING CONDITIONS OF SOME Rh/CeO2 CATALYSTS. Stud. Surf. Sci. Catal. 82, 507 (1994).
• A. Laachir, V. Perrichon, S. Bernal, J.J. Calvino y G.A. Cifredo. STUDY OF THE CO-CeO2 INTERACTION IN PRESENCE OF HIGHLY DISPERSED RHODIUM. J. Molec. Catal. 89, 391-396 (1994).
• W. van Schaik, S.H.M. Poort, G. Blasse, J.A. Pérez Omil y S. Bernal. A LUMINESCENCE AND HRTEM STUDY ON Cr3+-DOPED LaPO4 AND LaMgB5O10. Chem. Mater. 6, 755-760 (1994).
• S. Bernal, J.J. Calvino, G.A. Cifredo, J.A. Pérez Omil, J.M. Gatica and J.M. Pintado. ESTUDIO DE LA INTERACCIÓN O2-(Rh/CeO2) MEDIANTE TÉCNICAS DE ADSORCIÓN VOLUMÉTRICA, OTP Y MICROSCOPÍA ELECTRONICA DE ALTA RESOLUCIÓN. Actas del XIV Simposio Iberoamericano de Catálisis, Concepción (Chile), Vol. 1, 1-6 (1994).
• S. Bernal, J.J. Calvino, G.A. Cifredo, J.M. Gatica, C. Larese y J.M. Pintado. TERBIUM OXIDE AS SUPPORT OF HIGHLY DISPERSED METALS. STUDY OF THE Rh/TbOx CATALYTIC SYSTEM. J. Alloys and Compounds 225, 633 (1995)
• S. Bernal, F.J. Botana, J.J. Calvino, M. Marcos, J.A. Pérez Omil y H. Vidal TÍTULO: LANTHANIDE SALTS AS ALTERNATIVE CORROSION INHIBITORS. J. Alloys and Compounds 225, 638 (1995)
• S. Bernal, F.J. Botana, J.J. Calvino, G.A. Cifredo, J.A. Pérez Omil and J.M. Pintado HRTEM STUDY OF THE BEHAVIOUR OF Rh/CeO2 CATALYSTS UNDER HIGH TEMPERATURE REDUCING AND OXIDIZING CONDITIONS. Catalysis Today 28, 219-250 (1995).
• S. Bernal, G. Blanco, J.J. Calvino, G.A. Cifredo, J.A. Pérez Omil, J.M. Gatica y J.M. Pintado. CATALISIS MEDIOAMBIENTAL: APLICACION DE LA MICROSCOPIA ELECTRONICA DE ALTA RESOLUCION AL ESTUDIO DE LOS MECANISMOS DE DESACTIVACION EN CATALIZADORES TWC. Actas de la I Conferencia Europea de Ecología y Medio Ambiente. Editor: J.M. Sánchez Lamadrid. pag. 187-193 (1995)
• S. Bernal, J.J. Calvino, G.A. Cifredo y J.M. Rodríguez-Izquierdo. COMMENTS ON REDOX PROCESSES ON PURE CERIA AND Rh/CeO2 CATALYST MONITORED BY X-RAY ABSORPTION (FAST ACQUISITION MODE). J. Phys. Chem. 99, 11794-11796 (1995)
• T. López, M. Asomoza, R. Gómez, P. Bosh, J. M. Rodríguez-Izquierdo y M. A. Cauqui THERMAL DESCOMPOSITION AND FTIR STUDY OF PYRIDINE ADSORPTION ON Pt/SiO2 SONOGEL CATALYSTS Thermochim. Acta. 255 , 319-328 (1995)
• P. Bosch, T. López, M. Asomoza, R. Gómez, M.A. Cauqui, J.M. Rodríguez-Izquierdo Pt/SiO2 SONOGELS: SYNTHESIS AND CHARACTERIZATION Langmuir 11, 4328-4332 (1995)
• S. Bernal, J.J. Calvino, M.A. Cauqui, J.M. Izquierdo y H. vidal. SYNTHESIS, CHARACTERIZATION AND PERFORMANCE OF SOL-GEL PREPARED TiO2-SiO2 CATALYSTS AND SUPPORTS. Stud. Surf. Sci. Catal. 91 , 461-470 (1995)
• S. Bernal, F.J. Botana, J.J. Calvino, C. López, J.A. Pérez Omil y J.M. Rodríguez-Izquierdo. TÍTULO: SOME HREM CONTRIBUTIONS TO THE INVESTIGATION OF THE METAL/SUPPORT INTERACTIONS IN Rh/TiO2. J. Chem. Soc. Faraday Trans. 92(15), 2799-2809 (1996)
• S. Bernal, M.Cauqui, G.A. Cifredo, J.M. Gatica, C. Larese, J.A. Pérez Omil. CHEMICAL AND MICROSTRUCTURAL INVESTIGATION OF SOME Pt/CeO2 CATALYSTS REDUCED AT TEMPERATURES RANGING FROM 473 K TO 973 K. Catal. Today 29, 77-81 (1996)
• S. Bernal, G. Blanco, G. Cifredo, J.A. Pérez Omil, J.M. Pintado, y J.M. Rodríguez-Izquierdo REDUCIBILITY OF CERIA-LANTHANA MIXED OXIDES UNDER TEMPERATURE PROGRAMMED HYDROGEN AND INERT GAS FLOW CONDITIONS J. Alloys and Compunds (In Press)

5. INSTRUMENT FACILITIES

5.1. Equipment Belonging to our Research Group.

• Three Temperature Programmed Desorption/ Reduction/ Oxidation devices coupled to quadrupole mass spectrometers for the analysis of the evolved gases (TPD/R/O-MS). Flow regulation by mass flow controllers. One of them is equipped for running IKT (Isotopic Kinetic Transient) Experiments. A second one allows to perform pulse experiments. - Electronic Microbalance for Thermogravimetric Analysis under high vacuum and controlled atmospheres. Simultaneous analysis of the evolved gases by mass spectrometry.
• Temperature Programmed Desorption/Reduction/Oxidation with Thermal Conductivity Detector (TPD/R/O-TC). This device also includes - Flow regulation by mass flow controllers. - Electronically controlled pneumatic injection system for pulse experiments. - A/D Converter for digital storage of the experimental results. - PC-like microcomputer for control and data storage.
• Three Catalytic Activity Benches equipped with mass flow controllers. Gas Chromatography is used as analytical technique:
• Five High Vacuum manyfolds fully equipped for carrying out volumetric adsorption experiments.
• Fourier Transform IR Spectrometer, Mattson, model 5020, with double optical bench. One of the benches is specifically devoted to carry out Reflectance Diffuse (DRIFT) Studies under vacuum or controlled atmosphere at temperatures ranging from 295 K to 1173 K.
• Two Silicon Graphics workstations (IRIS 4D/TG, model 4D35TG+; and INDY, model R4400SC) specifically devoted to computer calculation of simulated High Resolution Transmission Electron Microscopy (HREM) Image. The available software includes: the EMS (Electron Microscopy Software) package, as well as some computer programs (EJE-Z and RHODIUS) developed by the Group.
• High Resolution CCD Camera and Computer Equipment for Digitalization and further Processing (SEMPER 6+ Software Package) of Experimental HREM Images.

5.2. University Facilities at the Faculty of Sciences

• Transmission Electron Microscope, JEOL, model JEM-2000 EX/THR; 200 kV, with Top Entry, for High Resolution Studies (Structural Resolution: 0.21 nm). It is equipped with an ion pumping system.
• Transmission Electron Microscope, JEOL, model JEM-1200 EX/(DCS); 120 kV, with side entry. It is equipped with EDS facilities for microanalysis and a STEM unit, JEOL, model EM-ASID 10.
• Scanning Electron Microscope, JEOL, model JSM-820 A, equipped with EDS facilities for microanalysis, LINK, model PCXA.
• Two XRD Powder Diffractometers, from Siemens and Philips, respectively. The latter is equipped with a High Temperature Chamber for carrying out "in situ" thermal treatments of the samples under controlled atmospheres.
• 400 MHz NMR Spetrometer, Varian, equipped with accesories for recording spectra of solid samples.
• Other Analytical Facilities: Plasma Ionization and Atomic Absorption Spectrometry.

CEZIRENCAT Home Page | CORDIS |

3/12/1996 Serafin Bernal