Carlo Dossi

Università degli Studi dell'Insubria | UNINSUBRIA · Department of Theoretical and Applied Sciences

This publication aims to disseminate a step-by-step process that walks through the conceptualization and building of a low-cost (~ $150 monitoring device for airborne fine particulate matter (PM2.5), based on miniaturized sensors and components. Details on the implementation of the hardware and software are provided which facilitate the data acquis...

The complete dissolution of silicate-containing materials, often necessary for elemental determination, is generally performed by microwave-assisted digestion involving the forced use of hydrofluoric acid (HF). Although highly efficient in dissolving silicates, this acid exhibits many detrimental effects (e.g., formation of precipitates, corrosiven...

Biomasses are emerging as alternatives to traditional synthetic carbon nanostructures to produce greener, carbon based, sensing platforms. More recently, biochar, a porous carbonaceous material produced by direct (i.e. solvent free) pyrolysis of biomasses, was also investigated, leading to a further decrease in the fabrication environmental footpri...

Volatile organic compounds (VOCs) represent one of the most important categories of pollutants, influencing the air quality and human health and well-being in indoor environments. In the present study, 12 selected VOCs were sampled using Tenax TA tubes and analyzed by thermal desorption combined with gas chromatography and a flame ionization detect...

Mercury substitution is a big issue in electroanalysis, and the search for a suitable, and less toxic, replacement is still under development. Of all the proposed alternatives, bismuth films appear to be the most viable solution, although they are still suffering some drawbacks, particularly the influence of deposition conditions and linearity at l...

The development of a scanning reactor for planar catalysts (SCR-PC) is here presented. With respect to other existing models, this reactor is able to scan catalysts even with low turnover frequencies, with a minimum sensed circular area of about 6 mm diameter. The downstream gas analysis is performed with a quaprupole mass spectrometer. The apparat...

Teeth are in close contact with foodstuffs: phenomena such as caries and wear of the crowns are precious keys to gather information on diet and cooking techniques. Phytoliths are granules of hydrated amorphous silica, which are deposited in the oral cavity while chewing fruit and vegetables and incorporated into dental calculus during its formation...

The use of a commercial wall-jet cell for alumina-based screen printed sensors has regained new life to flow injection techniques in voltammetry. Of the many theoretical advantages of flow injection stripping, the possibility of using external calibration is of primary importance to the applied analytical chemist, since higher throughput is gained...

Risk assessments from the European Union and the World Health Organization report values for acute and chronic toxicity of Cr(III) to Daphnia magna in the range of 0.6-111 mg/L and 0.047-3.4 mg/L, respectively. To understand whether factors other than the use of different test media and data reporting contribute to this variability, we tested the a...

A robust voltammetric method has been developed and validated for the determination of Fe(II) and Fe(III) in pharmaceutical iron polysaccharidic complexes. Undesirable low molecular weight iron complexes, at concentration about 3% in the pharmaceutical formulation, can be easily determined with good accuracy and precision. This methodology can be p...

A simple computerized potentiometric titrator is described for performing automated analyses of chloride ions on solid materials as well as the continuous determination of HCl in effluent gas streams. This versatility has been obtained by a dedicated instrumental design, which offers easy interfacing to catalytic reactors and flexibility in softwar...

The use of electroanalytical techniques for the speciation analysis of copper in four glaciated catchments is presented. The method is based on a competitive ligand equilibration scheme coupled with cathodic stripping detection (CLE‐CSV procedure). Issues related to the particular nature of the samples, i.e. their very low ionic strength, and their...

A new approach towards monuments, considering them as a passive sampler of pollution, is presented. Cultural Heritage objects suffer daily the damages of environmental pollution, especially in those areas interested by heavy traffic. Since monuments undergo only periodic conservation or maintenance works, surfaces are able to accumulate atmospheric...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The analytical performances of Competitive Ligand Equilibration with Cathodic Stripping Voltammetric detection of the labile fraction (CLE-CSV) were assessed. This speciation method enables the concentration of natural ligand(s) and their conditional stability constants for the complexation of the investigated metal to be determined through thermod...

A low cost, high performance ultraviolet digester was developed and tested in our laboratory. Its main features include limited costs (around 600 € for all the parts) and high efficiency toward total organic carbon (TOC) abatement. As a result the TOC of typical natural waters is reduced to less than 10% of its initial value with half an hour treat...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Poor recoveries are obtained if the BCR three-step sequential extraction is applied to 100 mg specimens rather than to 1 g. It is observed that analytes are lost during each phase separation which is carried out via centrifugation and can be hardly quantitatively performed on 100 mg sediment specimens. An alternative procedure, which is carried out...

An empirical approach is presented for validating trace metal profiles in tree rings for use as environmental archives. Concentration profiles of Zn, Cd, Cu, Pb and U in tree rings and lake sediments are compared for assessing the reliability of the former as an environmental proxy. Laser ablation sampling in conjunction with inductively coupled pl...

A large data set obtained by a one-year monthly determination of ions (F−, Cl−, Br−, NO3−, NO2−, PO43−, SO42−, Na+, K+, Ca2+, Mg2+, NH4+) and trace metals of environmental concern (Ni, Co, Mn, Fe) from the tributaries of Lake Como (Lombardy, Northern Italy) was treated by three-way Principal Component Analysis. The results showed that the chemical...

The development and validation of a method for the determination of mercury in sediments using a sector field inductively coupled plasma mass spectrometer (SF-ICP-MS) for detection is described. The utilization of isotope dilution (ID) calibration is shown to solve analytical problems related to matrix composition. Mass bias is corrected using an i...

Two different techniques for the evaluation of uranium content in four water samples are compared. The results obtained and reported in this paper show the good agreement between the two techniques used. This comparison looks as a good method to test the reliability of the measurements performed.

A new automated batch method for the determination of ultratrace metals (nanogram per liter level) was developed and validated. Instrumental and chemical parameters affecting the performance of the method were carefully assessed and optimized. A wide range of voltammetric methods under different chemical conditions were tested. Cadmium, lead and co...

Adsorptive cathodic stripping voltammetry (AdCSV) with HDME and a chloranilic acid ligand was used in the trace analysis of uranyl ions at pH = 2 in low-ionic-strength groundwaters around mining areas. Upon optimization, the limit of detection around 0.10 µg L−1 was found with linearity up to 10 µg L−1. In the abandoned mining area of Val Vedello (...

Water and snow chemistry of a high-altitude karst environment, the Monte Pelmo massif in the Dolomites (Eastern Alps, Italy), was investigated by a multidisciplinary analytical approach using ‘clean’ trace-metal techniques. Main ions of environmental significance (F−, HCOO−, Cl−, NO−2 , NO−3 , SO2−4 , Na+, H+4 , K+, Ca2+, Mg2+, HCO−3 )were analysed...

A chemometric approach based on Principal Component Analysis (PCA) has been proposed, in order to study chemical features (major and minor ions, total alkalinity, dissolved silica) of surface and deep waters of Lake Como (Northern Italy). The method allowed us to investigate the correlations between the analyzed ions in an easy-to-see way, using bi...

Fradusta glacier (Pale di San Martino massif), the second largest icefield in Italian Dolomites, is evidencing a fast retreat, with a surface area reduction of about 90% in the last 100 years, and a negative variation of glacier front of 115.5 m between 1926 and 2000. Analytical chemical studies, conducted on the field with portable instrumentation...

A voltammetric method for the determination of tin is proposed to minimise interferences from noble metals that are commonly encountered with other analytical techniques. Strong distortions of voltammetric peaks are observed in the presence of platinum. On the basis of a full investigation, the formation of an intermediate Sn(II)-Pt mixed chloro-co...

A prototype DRIFTS flow reaction chamber was designed and developed in order to find analytical application in the study of heterogeneous catalysts operating at high temperatures under fast transient gas feed conditions. Minimisation of dead-volumes allows gas replacement in 8-10s at 10mLmin(-1) total flow. To overcome problems related to the react...

Computerized analytical instruments of late 70's and 80's are facing rapid technological obsolescence, although they are often retaining good analytical performances. Responsibility is to be attributed to the fast advance in computer technology, which is leaving little or no back-compatibility with old standards and data formats. Rejuvenation may b...

The chemical speciation of copper in stream waters from Rutor Glacier was determined by cathodic stripping voltammetry with ligand competition against salicylaldoxime. The complexation of salicylaldoxime was calibrated at various calcium concentrations, the major competing cation in these waters. Copper concentrations ( 3 - 7 nM) were approximately...

Nei giorni 7 – 8 settembre 2001 è stata effettuata una campagna di campionamento di ghiaccio, neve ed acqua superficiale sul ghiacciaio della Marmolada (Dolomiti occidentali) che ha interessato sia la zona di accumulo delle precipitazioni nevose sia quella di ablazione del ghiac-ciaio alle fronti occidentale, centrale ed orientale. Le analisi chimi...

The utilization of organometallic complexes of palladium and platinum to form mono and bimetallic catalysts on basic magnesium oxide support was studied and rationalized. Thermoanalytical data in hydrogen flow suggested the uselessness of volatile, fluorinated organometallic precursors for platinum catalysts, because the strong chemical interaction...

A sampling campaign on Marmolada Glacier (Dolomites, Italy) was undertaken on 7-8 september 2001, in order to collect samples of ice, snow and surface waters for chemical analyses. Such analyses, conducted on the field with portable electroanalytical instrumentation and in the analytical laboratory, suggested the occurrence of strong chemical inter...

Dinitrogen (N-2) adsorption on overexchanged Cu-ZSM-5 (Si/Al=25, 104% ion exchange from copper acetate) was studied at 302 K by diffuse reflectance infrared spectroscopy (DRIFTS), N-2-adsorption isotherms, and temperature-programmed N-2 desorption (TPD). We found that Cu-ZSM-5 adsorbs N-2 at least in two different modes. The weaker mode, evidenced...

Dinitrogen (N2) adsorption on overexchanged Cu-ZSM-5 (Si/Al = 25, 104% ion exchange from copper acetate) was studied at 302 K by diffuse reflectance infrared spectroscopy (DRIFTS), N2-adsorption isotherms, and temperature-programmed N2 desorption (TPD). We found that Cu-ZSM-5 adsorbs N2 at least in two different modes. The weaker mode, evidenced by...

Hydrodechlorination of carbon tetrachloride was performed at atmospheric pressure over Pd and Pt catalysts supported on various inorganic oxides (Al2O3, MgO, CeO2) and obtained from different organometallic precursors (Pd(acac)2, [Pd(C3H5)Cl]2, Pt(acac)2 and Pt(CH3CN)2Cl2. Generally, Pd-based catalysts show low conversion levels and high selectivit...

High-altitude alpine valleys may be considered as ideal field laboratories for the interdisciplinary teaching of Environmental Sciences to undergraduate students in a Laurea degree, since different typologies of sampling sites (rivers, lakes, glaciers) may be found within walking distance, and students are encouraged to develop cooperative learning...

Hydrodechlorination of carbon tetrachloride was performed over Pd and Pt on MgO catalysts obtained from different precursors. The Pd samples show low activity and high selectivity to deep hydrogenolysis of C-Cl bonds to CH3(ads) fragments leading to C1 - C7+ hydrocarbons, following a typical Schulz-Flory distribution for alkyl polymerization. On th...

The development of an analytical method for the determination of platinum in MgO based Pt/Sn catalysts is described. Electrothermal atomic absorption spectroscopy (ETAAS) was chosen because of its high sensitivity and robustness against spectral interferences. All the sources of chemical interferences were statistically analyzed and corrections wer...

Pd(acac)2 was supported on a highly dehydroxylated and decarbonated magnesium oxide surface (MgO500), on an untreated MgO surface (MgOAIR), and on a silica (SiO2450). EXAFS and DRIFT data indicate that the organopalladium complex is adsorbed intact on all the surfaces, but its dispersion is dependent on the nature of the surface. On MgO500, dispers...

Pt-Sn/MgO catalysts prepared by Surface Organometallic Chemistry were investigated by 119Sn Mössbauer spectroscopy. The results indicate that, on the reduced catalyst, most of the tin forms bimetallic particles with a Sn-rich surface, whereas the remainder is present as Sn(II) and Sn(IV) compounds. Changes of the structure of the particles after a...

The influences of low-temperature redox cycling and of the presence of chloride on the redox and chemisorptive properties of Rh/Ce0.6Zr0.4O2 were investigated by means of volumetric hydrogen chemisorption, temperature-programmed reduction, and temperature-programmed desorption. This was achieved by conducting experiments on two samples of the mater...

A multi-technique analytical approach has been used to show that carbonaceous material entrapped in the channels system of Cu- ZSM-5 catalysts may contribute to maintain the copper ions in the oxidation state +1. This suggests that the reduction of Cu2+ to Cu+ does not only occur via water elimination from CuOH+ species or via oxygen evolution from...

The utilization of insitu DRIFT spectroscopy combined with advanced thermoanalytical techniques (temperature programmed decomposition, TPDE; temperature programmed oxidative decomposition, TPOD) allows the characterization of redox behavior of copper ions inside ZSM-5 zeolites. The oxidation of carbonaceous impurities inside the solid matrix to CO...

We prepared H–ZSM-5 (Si/Al=66), Fe–S-1 (Si/Fe=66), and Silicalite-1 (S-1) according to the methods described by Bellussi and coworkers, and compared their ion-exchange capacity for copper ions. The Cu–ZSM-5, Cu–Fe–S and Cu–S-1 samples thus obtained have been investigated as catalysts for the NO decomposition reaction at 773 K. We found that using c...

Rhodium–tin bimetallic particles entrapped in NaY cages were used to study the mechanism of tin-promotion in the selective hydrogenation of α,β-unsaturated aldehydes. These model materials were obtained by chemical vapour deposition (CVD) and subsequent H2 reduction of Sn(R)4 (R=C2H5; C6H5) onto reduced Rh/NaY samples that were prepared by ion-exch...

Magnesia-supported Sn–Pt catalysts were prepared by reaction between preformed platinum metal particles and Sn(n-C4H9)4. HRTEM and H2-chemisorption data confirm the synthesis of very small tin-decorated platinum particles (∼1.0 nm mean diameter). Preliminary studies on catalytic hydrogenation of citral in a trickle-bed reactor reveal that 97% selec...

Rh–Sn/SiO2bimetallic catalysts were prepared by “traditional” coimpregnation with aqueous solutions of RhCl3and SnCl2. Their catalytic properties were used to study the mechanism of tin promotion in the liquid-phase selective hydrogenation of citral. The structural evolution during the activation treatments has been investigated by in situ EXAFS sp...

A chemical vapour deposition (CVD) procedure has been adopted for the preparation of Pd/NaY, resulting in a high dispersion of the metal phase, characterised by a bimodal distribution of particle size. The most abundant particles (80%) are about 25 Å in size, corresponding to almost twice the dimension of the zeolitic supercages. To identify their...

We prepared H-ZSM-5 (Si/Al=80), amorphous mesoporous silica–alumina (MSA, Si/Al=90), and Silicalite-1 (S-1) according to the methods described by Bellussi and co-workers, and compared their ion-exchange capacity for copper ions. The Cu-ZSM-5, Cu–MSA and Cu–S-1 samples thus obtained have been investigated as catalysts for the NO decomposition reacti...

The thermochemical behavior of [Pd(acac)2] adsorbed onto different magnesium oxides has been studied under reducing conditions by means of the TPRD (temperature-programmed reductive decomposition) technique coupled to mass spectrometry. The thermal profiles of the different decomposition products have been rationalized in terms of chemical interact...

Criteria for designing the man suitable experimental setup for TPD TRP measurements are discussed in detail. Interfacing the control and measurement components with a PC represents a crucial step in this operation. Two different approaches are considered: the first hosed on a computer-linked gas chromatographic integrator, the second featuring an a...

Dinitrogen chemisorbs on two neighbouring copper atoms of Cu-ZSM-5 catalysts that are demonstrated to be the active sites for NO decomposition.

The use of AAS and UV-VIS methods for the determination of rhodium in silica supported catalysts is critically analysed to establish limits and fields of applicability to real working materials. The effectiveness of different digestion procedures of the metal phase is also widely investigated as a function of the thermal treatment of the catalyst a...

The combination of diffuse reflectance Fourier transform infrared spectrometry and gas chromatography (DRIFT-GC) was applied to the thermal characterization of solid materials. In the instrumental design, particular attention was devoted to minimizing the time delays between the responses of the DRIFT and the GC detectors. It was thus possible to c...

Glacial streams are remarkable ecosystems and have been studied since the last thirty years because of their unique and interesting features. First, they are the simplest way of understanding subglacial hydrology and the chemical and physical weathering taking place beneath glaciers (1,2). Water quality studies allow assessing the contribution of t...

Methanol synthesis over bimetallic FeIr/MgO catalysts prepared from mixed-metal carbonyl clusters, was studied with the aim of clarifying the role of the Fe/Ir ratio in the precursor and the influence of process parameters. Upon impregnation, the molecular precursors are physisorbed on the magnesia surface. Active catalysts are obtained by H2 treat...

Cluster-derived rhodium catalysts, prepared from salts of the cluster anion [Rh12(CO)30]2− supported on silica, have been studied in ethylene hydroformylation. A catalyst pre-treatment was carried out in Ar at 393 K before the admission of the hydroformylation mixture. The selectivity for propanal formation depends on the alkaline countercation in...

Specific studies carried in Milan laboratory in the application of metal carbonyl clusters to preparation of supported catalysts are reviewed. Examples are reported of catalysis by heterogeneous organometallic surface species, such as 1-butene isomerisation catalysed by silica-anchored osmium carbonyl species, or of catalysis by very small metal pa...

A Pt/HL model catalyst has been obtained by chemical vapor deposition of platinum hexafluoracetylacetonate and structurally characterized by EXAFS. In the conversion of methylcyclopentane at 350°C, the selectivity is consistent with the typical bifunctional nature of the active sites. EXAFS results show that agglomeration of metal particles is grea...

Allyl(cyclopentadienyl)palladium was selectively introduced inside the cages of the zeolite NaY via chemical vapour deposition in Ar at 25 °C. Palladium clusters were then formed by thermal removal of the volatile ligands under H2 at 300 °C. High-resolution transmission electron microscopy measurements indicated the formation of large palladium clu...

Magnesia-supported palladium catalysts were prepared from chemical vapour deposition (CVD) of [Pd(C3H5)(C5H5)] and incipient wetness impregnation of [Pd(C3H5)Cl]2 and [Pd(acac)2]. DRIFT spectroscopy of adsorbed CO on prereduced catalysts indicates that the electronic state of metal particles depends on the preparation methodology and markedly on th...

Intrazeolite redox chemistry of manganese has been exploited by the use of vapor-deposited Mn2(CO)10 complex onto NaY.

The analytical GC–MS characterization of polycyclic aromatic hydrocarbons (PAHs), formed as by-products in the model reaction of methylcyclopentane reforming, is proposed as a convenient tool for fingerprinting the nature of active sites in heterogeneous catalysts. The by-products obtained with non-acidic Pt/KL and Pt/NaY catalysts (platinum partic...

The structural evolution of non-acidic chemical-vapour deposition (CVD)-based Pt/KL catalyst has been investigated by in-situ extended X-ray absorption fine structure (EXAFS) spectroscopy. After in-situ reduction (H2, 400 °C), EXAFS results suggested the presence of small metal particles which may be localized inside the KL-zeolite channels. After...

Cluster-derived FeIr/MgO catalysts prepared from [Et4N]2[Fe2Ir4(CO)16] and [Et4N]2[Fe2Ir2(CO)12] exhibit high activity in methanol synthesis from CO + H2. The catalyst performance improves significantly upon raising the Fe:Ir ratio in the precursor from 2:4 to 2:2; with the latter sample, at 488–523 K and 6.1 MPa, methanol productivities up to 100...

Pd/NaY and Pd/NaHY catalysts have been obtained by chemical vapor deposition of allylcyclopentadienylpalladium and characterized by temperature-programmed reductive decomposition and by EXAFS. In the conversion of methylcyclopentane at 300°C, the non-acidic catalyst shows a constant 100% selectivity towards ring-opening without significant coke de...

High activity and selectivity in methylcyclopentane aromatization is observed with chlorine-free Pd/MgO catalysts prepared from organometallic precursors.

Manganese-promoted rhodium/NaY catalysts have been prepared by ion exchange and subsequent H-2 reduction and by chemical vapour deposition (CVD) of [Rh(CO)2(acac)] and Mn2(CO)10 followed by thermal decomposition. Carbonyl FTIR spectra reveal significant differences between monometallic Rh/NaY and Mn/NaY and their bimetallic counterparts and they de...

Quadrupole mass spectrometry has been applied to the investigation of the chemical reactivity of supported organometallic complexes as precursors of heterogeneous catalysts. The required high sensitivity to CO and CO2, together with an improved versatility, is obtained by a combined mass spectrometric and gas chromatographic approach.

Platinum hexafluoroacetylacetonate can be selectivity introduced inside KL zeolite channels via CVD in a flow of Ar at 70[degrees]C. Metal particles are then formed via thermal removal of the volatile organic ligands under H[sub 2] at 350[degrees]C. In situ DRIFTS and EXAFS measurements suggest the formation of very small Pt clusters with a nucleop...

The OM-CVD (Organometallic Chemical Vapor Deposition) technique has been applied to the preparation of zeolite-supported Pd and Pt catalysts for hydrocarbon conversion. This has been achieved via a two step process; the organometallic precursor is first deposited inside zeolite cages and then decomposed under controlled reduction conditions to meta...

This paper describes, at a molecular level, the organometallic chemistry which occurs during the adsorption of Os3(CO)12 on magnesia. When the magnesia has a high content of surface carbonates, the simple physisorption is followed by oxidative addition of hydroxyl groups to an Os—Os bond of Os3(CO)12. When the magnesia surface is highly decarbonate...

The reductive carbonylation of silica-supported MCl3·3H2O (M=Rh, Ir) was studied at atmospheric pressure under CO and under a mixture of CO and H2O. It was observed that these salts may be converted respectively into [Ir(CO)3 Cl]n and [Rh(CO)2Cl]2 under CO. At 70 °C, in the presence of CO and H2O, Ir4(CO)12 is selectively obtained. Under the same e...

The surface reactivity of Ir4(CO)12 supported on silica has been investigated by means of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed decomposition techniques. The initial stage of physisorption from a solution results in the deposition of large crystallites (ϕ > 2µ) of Ir4(CO)12, unevenly di...

A new theoretical approach has been used to analyze the X-ray absorption cross section of Os3(CO)12 carbonyl cluster. The method is based on a direct fit of the experimental cross section which makes use of theoretical signals associated with relevant atomic configurations in the molecule. In the case of the OsCO arrangement, it has been found th...

A study has been made of the reductive carbonylation of 2,4-dinitrotoluene (2,4-DNT) to 2,4-diisocyanotoluene (2,4-TDI) with catalysis either by [Pd(isoquinoline)2], in the presence of Fe2O3 and MoO3 or of Fe2(MoO4)3 as cocatalysts, or by Pdo complexes without cocatalysts. In the case of catalytic systems based upon [Pd(isoquinoline)2Cl2] the react...

The chemical behavior of supported metal fragments obtained from metal carbonyl clusters has been shown to be dependent upon the acid-base properties of the surface of the inorganic oxide and the chemical reactivity of the metal cluster precursor. This ‘molecular approach’ to material science, heterogeneous catalysis in particular, via supported cl...

The surface chemistry of supported organometallic clusters as precursors of heterogeneous catalysts is investigated by means of DTG (differential thermal gravimetry) and TPOD (temperature-programmed oxidative decomposition) techniques, as unique signatures of the occurrence of chemical interactions between the organometallic cluster and the surface...

The SiO2-supported [Rh12(CO)30]2- cluster, as K+ salt, is a stable and active catalyst for the heterogeneous hydroformylation of ethylene at atmospheric pressure.

The surface organometallic chemistry can be defined as the study of the reactivity of organometallic complexes, in particular molecular metals carbonyl clusters, with the surface of microporous metal oxides and, by extension, of zeolites.

The surface reactivity with hydrogen of silica-supported M3(CO)12 (M = Ru, Os) has been investigated at atmospheric pressure and temperatures between 25 and 100°C. Pure H4M4(CO)12 complexes are selectively obtained and almost quantitatively recovered from the solid sample by solvent extraction. In the case of H4Os4(CO)12, significative advantages o...

The initial stage of Ir4(CO)12 physisorption on SiO2 from solutions and the subsequent modifications induced by heating under different atmospheres are discussed with the help of XPS results obtained on samples treatedin situ. Ir4(CO)12 is shown to physisorb as crystallites. A good dispersion of crystallites on SiO2 is obtainedvia heating at 373 K...

The silica-anchored hydrido cluster HOsâ(CO)ââ(OSi) is easily prepared from physisorbed Osâ(CO)ââ. Chemical displacement from the surface with HF leads to the isolation of pure HOsâ(CO)ââ(OH). This approach is far simpler and gives much higher yields than the conventional syntheses in solution.

CO hydrogenation has been studied over reduced Pd/NaY; a pronounced structure sensitivity was observed. Catalysts containing highly dispersed Pd clusters initially showed high selectivity towards CH4, but as the Pd particles grew during the reaction the selectivity changed towards CH3OH, CH3OCH3 and higher hydrocarbons. On catalysts initially conta...

The title reaction has been investigated at 115°C using HOsâ(CO)ââ(OSi chemical bond) as catalyst or catalyst precursor. By FTIR and XP spectroscopy and by TPDE, evidence exists for the in situ formation of molecular oxidized osmium moieties, covalently anchored to the surface, which are the active catalytic species. The intermediate formation of...

Carbon monoxide, carbon dioxide and methane, evolved in very low amount during temperature programmed decomposition of transition metal cluster catalysts, can be determined quickly (<3 min) by gas chromatography on a Porapak S column. Catalytic conversion of the CO and CO2 to methane makes it possible to use a hydrogen fiame ionization detector. Th...

The surface reactivity of Os3 (CO)12 supported on silica and alumina has been investigated under oxygen atmosphere by means of FTIR and XP spectroscopy and temperature programmed decomposition (TPDE) techniques. Experimental evidence for the formation of molecular [Os(CO)x(OM)2]n (x=2, 3; M=Siε, Al< surface species has been obtained. The higher sta...

Addition of Re markedly changes the activity, selectivity, and stability of Pt/NaY and Pt/NaHY catalysts for n-heptane conversion at 500°C and 0.5 MPa. The effect of Re depends strongly on the method of catalyst preparation. With the volatile Re2(CO)10 carbonyl as precursor, Re is preferentially deposited in the supercages of the zeolite. In the pr...