Nicola Pernicone

• Dr
• Consultant at Ma.Tec. Materials Technologies

Catalytic reforming of CH4 with CO2 was investigated on mono and bimetallic Pd(or Pt)-Ni based samples supported on Al2O3 and ZrO2. A simple temperature-programmed procedure was used to study both reforming and coke formation via CH4 or CO decomposition. Catalysts supported on zirconia are more active than alumina-supported samples. The addition of...

The various physical properties characterizing the mechanical strength of catalysts are discussed: abrasion resistance, crush strength, attrition resistance. The related measurements have been performed mainly using ASTM standard methods with some improvements. It is shown how modifications of the manufacturing technology can improve the abrasion r...

The sulfur poisoning of carbon-supported bimetallic Pd–Au systems was investigated. Catalytic activity results for benzaldehyde hydrogenation clearly show that gold addition improves catalyst resistance to sulfur poisoning with respect to the monometallic Pd-based sample. Samples were characterized by pulse-flow CO chemisorption and XRD in order to...

A set of kinetic tests on a promoted Ru/C catalyst for ammonia synthesis has been carried out under industrially relevant reaction conditions (T = 370−460 °C, P = 50−100 bar). The results have been elaborated by using some kinetic models either derived from literature or here-developed. The best results, as for fitting and consistency of the optimi...

Quantitative measurements of CO chemisorption in the range 140–180 K, supported by FTIR data on adsorbed CO, were performed on Au/TiO 2 , Au/Fe 2 O 3 , and Au/CeO 2 catalysts. On the first two samples, which had similar particle size distributions, an average Au/CO chemisorption stoichiometry of about 3, referred to step-edge Au atoms, was found. O...

In the present work, we compared the catalytic activity and mainly the stability under the usual ammonia synthesis conditions, of some carbon supports, differing as for their nature, purity and temperature of pretreatment. The effect of catalyst composition (metal and promoters loading) on stability was also investigated. XRD and N2 adsorption/deso...

As the techniques presently used for routine measurements of nanoparticle size are largely unsatisfactory, especially for supported metal catalysts, new guidelines and procedures are described that allow us to obtain more accurate and reliable values of nanodimensions by chemisorption. Improved values of turnover frequencies will result, with benef...

Contradictory results about the best oxidic precursor of Fe ammonia synthesis catalyst prompted the present comparative investigation on wustite- and magnetite-based catalysts. Many physical (density, porous texture, crystalline phases, reduction rate, metal surface, abrasion loss) and catalytic (kinetic constants, thermoresistancy) properties have...

A standard chemisorption procedure has been set up for the determination of Ru dispersion in Ru/C catalysts. Pulse chemisorption of oxygen was carried out at 0 °C, after having proved that no corrosive chemisorption phenomena are present. An average chemisorption stoichiometry was experimentally determined through measurements on Ru black. The proc...

A polydomain internal structure was evidenced by means of High Resolution Transmission Electron Microscopy (HRTEM) in palladium nanoparticles of two 5% Pd/SiO2 catalysts prepared by impregnation technique. Such poly-domain structure biased the line broadening analysis of the XRPD patterns, from which highly underestimated average diameters were obt...

Due to the multiplicity of problems recently evidenced by the widely used N2O decomposition technique, the oxygen chemisorption technique for the measurement of Cu surface area was updated and optimized. A standard procedure was defined, which allows to obtain reliable and reproducible data. In particular, no arbitrary assumption was made for the C...

Following our previous papers regarding Pd/C and Pd/SiO2 catalysts, the determination of the Pd/CO average chemisorption stoichiometry from experimental data has been extended to the Pd/alumina system. To this purpose, the Pd crystallite size determined by the well-established line-broadening (LB) method, using X-ray powder diffraction (XRPD) assoc...

Pd catalysts on different supports (active carbon, silica, alumina) were studied for the selective hydrogenation of benzaldehyde to benzyl alcohol. They were characterized by TPR, CO chemisorption and XRD. Batch hydrogenation tests were performed before and after sulfur poisoning. Strong metal–support interaction was found for Pd/alumina, giving hi...

A series of carbon-supported, ruthenium-based catalysts, variously promoted with alkali and alkali-earth compounds, were prepared, aiming at investigating the effect of such promoters on catalyst activity and stability. It was found that a simultaneous action of three promoters (K + Ba + Cs) maximised both activity and thermal resistance of the cat...

The influence of preparation variables on the physical and catalytic properties of the Pd- Au/C system, taking benzaldehyde hydrogenation as a probe reaction, has been investigated. Catalysts were prepared by wet impregnation (simultaneous and consecutive). TPR, CO chemisorption and WAXS were used for catalyst characterization, in addition to catal...

In this work we have determined, on a series of 0.5% Pd/C catalysts, the palladium particle sizes by the following physical techniques:  (i) X-ray diffraction (XRD) line broadening (LB) method, associated with the Rietveld method, (ii) small-angle X-ray scattering, and (iii) transmission electron microscopy. The catalysts, suitably aged at differen...

This study uses X‐ray diffraction (XRD) techniques to investigate the nanostructural features of a series of four Pd/C catalysts, which had the same load, 0.51 ± 0.02 wt%, as palladium, with significantly different dispersions, obtained by applying different temperature ageings up to 873 K. By means of a Rietveld refinement, performed using a speci...

A series of alkali- and/or alkali-earth-promoted, carbon-supported Ru catalysts have been prepared by impregnation from aqueous solutions of the precursors. The supports have been pretreated by heating in inert atmosphere at various temperatures, followed by partial oxidation in air at 425°C and then by hydrogen treatment at 900°C. The catalyst sam...

The need for standard methods and reference materials (RM) for measurements relating to the porous structure of solids is stressed. Seven available standard methods developed by ASTM Committee D-32 ″Catalysts″ are listed, including tests for surface area, pore volume, D-3908 Hydrogen Chemisorption on Supported Platinum on Al2O3 Catalysts by the Vol...

Commercial 0.5% Pd/C catalysts for the production of purified terephthalic acid (PTA) have been investigated by several physical techniques (SEM-EDS, CO chemisorption, XRD) and by activity tests performed in conditions strictly similar to those of industrial operation. These catalysts show a strongly external Pd distribution, pointing to high Pd co...

After a description of the basic concepts concerning porosity in solid materials, the BET method for surface area determination is discussed, and the different techniques and apparatuses are reviewed. Methods for pore volume measurements are subsequently addressed, in connection with the various classes of materials: mesoporous, microporous and mac...

Several commercial ammonia synthesis catalysts have been studied by TPR and XRD in an Fe3O4 and prereduced-passivated state. Extension of TPR experiments up to 1200°C provided information which was yet unknown. From TPR profiles and XRD patterns of Fe3O4 catalysts, some conclusions can be drawn about the catalyst preparation procedure and expected...

Measurements of β-PdHx stoichiometry by hydrogen TPD and of Pd dispersion by CO chemisorption has shown that in Pd−SiO2 catalysts the formation of β-PdHx is more and more hindered with the increase of Pd dispersion in the whole dispersion range. A linear relationship exists between β-PdHx stoichiometry and temperature of its hydrogen TPD peak.

Structural investigations of dispersed Pd/SiO2 catalysts were carried out with XRD and SAXS techniques, supported by TPR and CO chemisorption measurements. The stoichiometry of Pd hydride, -PdHx, was determined by measuring the shift of Pd 111 XRD reflection in the presence of hydrogen. It was confirmed thatx decreases when the metal dispersion inc...

Among the various metals able to catalyze hydrogenation reactions, palladium is probably the most interesting one, due to its special feature of interacting with hydrogen in two different ways, surface adsorption and bulk absorption, both of them having relevance to the catalytic phenomenon. Various Pd-based bimetallic systems have been investigate...

The aim of this paper is to give an impression of the work of the recently disbanded IUPAC Sub-Committee on the Characterization of Porous Solids. It provides a brief description of the development, content and philosophy of the Recommendations of the Sub-Committee, to be published in Pure and Applied Chemistry. An outline is given of the terminolo...

The general principles regulating the deactivation of oxidation catalysts based on metal oxides are firstly outlined, showing that the main causes of deactivation for such catalysts are: thermal sintering, solid state reactions and loss of active components. The three corresponding deactivation mechanisms are briefly described. For each of them the...

Ammonia synthesis is one of the most important processes operated by the chemical industry. Modern ammonia synthesis plants can produce up to 1800 tons of ammonia per day. Clearly, the design of the large reactors requires powerful and reliable calculation methods and the availability of a sound kinetic equation is an essential requirement. It is n...

After having defined the main types of deactivation causes responsible for decreased catalyst life in industrial plants (chemical and depositive poisoning, thermal and chemical sintering, solid state reactions, loss of active components), the requisites of reliable life tests are discussed. It is shown that relative accelerated tests are needed: tw...

Metal-loaded zeolites combine the advantages of shape selectivity and high metal dispersion and have therefore been investigated from the point of view of their catalytic performance, especially for hydrogenation and Fischer–Tropsch synthesis. In the case of iron, Mössbauer spectroscopy offers a valuable means for the characterization of the electr...

Pd-silica catalysts were prepared from various precursor Pd compounds and characterized as reducibility, metal dispersion and catalvtic activity in 1-octene hydrogenation. Preliminary IRS measurements allowed a better definition of CO chemisorption stoichiometry. A strong influence of the precursor on Pd dispersion was detected. The hydrogenation o...

A brief account is given of the present status of the research work done by the BCR Working Group "Particulate Materials". The work devoted to the development of Reference Materials for low surface area and meso-macro pore size is discussed in some detail. Suitable RMs in these areas are expected to become available in the course of 1983.

Samples of aged catalyst discharged step by step from industrial tubular reactors have been characterized by surface area, chemical analysis, Mössbauer spectroscopy, XPS, electron microprobe and kinetic measurements. (change-para-here) The data so collected allow to suggest reasonable explanations for the various phenomena occurring during catalyst...

Review: Bericht über einen Vortrag, der auf dem "Secondl International Symposium on the Scientific Bases for the Preparation of the Heterogeneous Catalysts" in Louvain-la-Neuve, Belgien, vom 4.9.

After having strictly defined the concept of activation by reduction the industrial procedures for the reduction of the catalysts for high and low temperature CO conversion and for ammonia synthesis are reported and the basic principles on which they are based are discussed. Emphasis is given to the difficulty of obtaining laboratory-scale data tha...

The kinetics of magnetite reduction by hydrogen at low temperatures have been studied by TG, using very small samples. The reduction rate was found to decrease with the increase in the sample mass and also to depend on the method of sample loading on the pan. An induction period is generally present. In the presence of water both reaction rate and...

The present state of research on the FeMo oxide catalyst is summarised. The preparation of the catalyst is described and the nature of the precipitated amorphous, hydrous iron molybdate is discussed. After thermal dehydration and crystallisation a Fedefective iron molybdate is obtained, as shown by X-ray diffraction studies. The preparation of oth...

Results on hydrogen reduction of pure magnetite to iron at low temperature are reported as part of research on ammonia synthesis catalyst. Experimental work was carried out by thermogravimetry and by electron microscopy. The reduction has a typical S-shaped kinetic curve, with a poorly reproducible induction period. The slope of the reduction curve...

The oxidation of methanol to formaldehyde by the solid phase oxygen of a MoO3Fe2(MoO4)3 catalyst was studied with a pulse microreactor. Temperature, pulse flow rate and methanol concentration were chosen as independent variables. A defective mass balance always occurred. The kinetic results were explained on the basis of catalyst surface heterogen...

The validity of a structural model previously proposed by Hosemann, Preisinger, and Vogel, Ber. Bunsenges. Phys. Chem.70, 796 (1966) for the ammonia synthesis catalyst (α-Fe promoted with alumina) has been investigated by X-ray diffraction, Mössbauer spectroscopy and DTA. X-Ray diffraction data confirm the presence of paracrystallinity in the catal...

Reduction is an important step in the preparation of many industrial catalysts. The Temperature Programmed Reduction Technique, based on the continuous determination of hydrogen consumption during reduction, allows to neglect the effect of any other reaction simultaneous with the reduction. In this paper the evaluation of the TPR technique as a too...

The kinetics of methanol oxidation over MoO3Fe2(MoO4)3 catalyst were studied by means of a differential flow reactor and a pulse reactor in the temperature range 180–280 °C. The reaction rate does not depend on the partial pressures of the reactants, except for the lowest ones. Formaldehyde and, especially, water act as inhibitors of the reaction....

The kinetics of methanol oxidation over MoO3Fe2(MoO4)3 catalyst were studied by means of a differential flow reactor and a pulse reactor in the temperature range 180-280 °C. The reaction rate does not depend on the partial pressures of the reactants, except for the lowest ones. Formaldehyde and, especially, water act as inhibitors of the reaction....