F. Boccuzzi

• professor
• l professor at University of Turin

Gold-based catalysts over different supports were investigated in the oxidative esterification of furfural by employing an efficient and sustainable process. The catalytic performances follow the trend: Zirconia–Au > Ceria–Au ≫ Titania–Au. Zirconia came out to be the best support option to promote activity, selectivity and also stability. The chemi...

The procedures leading to the preservation of catalytic performances of Au/ZrO2 samples have been investigated. The three potential causes of deactivation, namely the particle growth by sintering of gold nanoparticles, the metal leaching and the formation of un-reactive species which inhibit the reaction, have been evaluated. In particular, this pa...

Two gold based catalysts supported on ceria prepared by different methods (urea gelation coprecipitation, UGC, and coprecipitation, CP) have been synthesized and tested in the WGS reaction, showing quite different catalytic behaviors. Interestingly, the two catalysts have the same gold loading (3 wt% Au was inserted by deposition-precipitation) and...

An Au/ZrO2 catalyst was prepared and characterized in order to study the role of gold nanosize in the conversion of furfural into methyl furoate by oxidative esterification with O2 and methanol, without NaCH3O. The comparison with the Au/TiO2 reference catalyst provided by the World Gold Council and with an Au/ZrO2 catalyst treated at 600 °C in oxy...

a b s t r a c t The effect of preparation method on structural properties and activity of Cu-Mn spinel oxide catalysts for the low-temperature water-gas shift reaction (LT-WGSR) has been studied. Single-step urea-combustion and coprecipitation procedures were used for synthesis of the catalysts. Catalyst characterization was per-formed by N 2 physi...

Highly dispersed gold based catalysts supported on zirconia were employed in the oxidative esterification of furfural by an efficient and sustainable process. Au/ZrO2 catalysts were calcined at different temperatures in order to modulate gold nanosize. A detailed characterization was carried out for the sake of ascertaining if micro structural chan...

the urea gelation-coprecipitation pathway, were used as supports of gold catalysts. The impact of the nature of support on the catalytic performance for oxidation of CO, CH3OH and (CH3)2O was studied. Very high catalytic activity was demonstrated by gold catalysts supported on CeO2 and mixed CeO2-Fe2O3 (about 100% conversion of CO and CH3OH at 40oC...

Abstract. This paper reports results on the application of two different preparation methods, namely deposition-precipitation (DP) and modified deposition-precipitation (MDP), for the synthesis of ceria-supported gold and silver catalysts. The effect of the synthesis procedure on the catalytic performance for abatement of air pollutants - CO, CH3OH...

a b s t r a c t New gold catalysts supported on ceria modified by addition of ZrO 2 have been synthesized and tested in the water-gas shift reaction (WGSR) at low temperature, where they displayed better catalytic activity than gold supported on pure ceria, following the trend: AuCe50Zr50 > AuCe80Zr20 > AuCe. Morphologic, textural, structural and s...

Pd catalysts supported on silica were tested for H2O2 direct synthesis under very mild (1 bar, 20 °C, no halide addition) and nonexplosive conditions. Other catalytic tests were performed at higher pressure using a solvent expanded with CO2. The optimum Pd content is 1.5 wt.%. Calcination is mandatory to preserve catalytic performance and recycle t...

The adsorption of CO on the supported gold nanoparticle catalysts Au/TiO2, Au/Fe2O3, and Au/ZrO2 was examined using infrared transmission spectroscopy to quantify the isobaric CO coverage as a function of temperature. The Temkin adsorbate interaction model was then applied to account for the adsorption behavior. To test the general applicability of...

Two different synthesis routes, in particular deposition-precipitation (DP) and modified deposition-precipitation (MDP) have been used for preparation of gold/ceria catalysts. The catalysts have exhibited significant differences in CO, CH3OH and (CH3)2O oxidation. The most pronounced effect of different preparation methods was registered in the CO...

Pd catalysts supported on silica were tested for H2O2 direct synthesis under very mild (1 bar, 20 �C, no halide addition) and nonexplosive conditions. Other catalytic tests were performed at higher pressure using a solvent expanded with CO2. The optimum Pd content is 1.5 wt.%. Calcination is mandatory to preserve catalytic performance and recycle t...

A treatment of the Temkin model was developed for describing the adsorption of CO on gold. In this presentation, it is made clear that the Temkin thermodynamic model is an extension of the Langmuir model that incorporates a linear variation of the adsorption enthalpy. It is also stressed that the Temkin model can be interpreted in terms of two dist...

Gold catalysts were prepared by deposition-precipitation method on mixed Ce–Fe composite oxides, synthesized by the urea gelation coprecipitation pathway. The impact of the support composition on the catalytic performance for the water-gas shift reaction was studied by varying the Ce/(Ce + Fe) ratio. The following activity order was observed: Au/Ce...

Ce–Fe mixed oxides were prepared by urea gelation coprecipitation method and used as supports of gold catalysts. The impact of the support composition on the catalytic performance for the preferential CO oxidation (PROX) was studied by varying the Ce/(Ce + Fe) ratio. A deep characterization study by different tools such as XRD, HRTEM, TPR and FTIR...

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.

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 adsorption and the surface reactions of ammonia and nitric oxide on differently pretreated Ru/TiO2 samples have been investigated by means of FTIR spectroscopy. On all the samples, both oxidized and reduced, the ammonia is adsorbed at room temperature in an undissociated form on different Ti4+ surface ions, (at coordinatively unsaturated sites)...

The effect of the addition of various amounts of sulfates to a zirconia support and its possible role during the Au deposition–precipitation step was examined. The high activity showed by the Au/ZrO2 catalysts in the WGS reaction was enhanced by the action of sulfates on the support. SO42− addition to zirconia brings a higher gold dispersion due to...

Bimetallic Pd–Au samples supported on zirconia were prepared by different methods and tested for the direct synthesis of hydrogen peroxide under very mild conditions (room temperature and atmospheric pressure), outside the explosion range and without halides addition. Further catalytic tests were performed at higher pressure using solvents expanded...

The impact of ceria doping by Zn (atomic ratio Zn/(Zn + Ce) = 0.05) on the structural and catalytic properties of Au/CeO(2) catalyst was studied. The ceria modification influenced the catalytic activity toward purification of hydrogen via water-gas shift (WGS) and preferential CO oxidation (PROX) reactions in a different way: it diminished the WGS...

The analysis of FTIR absorption spectra of CO and of12CO-13CO isotopic mixtures is reported for gold catalysts supported on a number of oxides. Relationships between the nanostructure and the CO adsorbing properties of the different gold catalysts are discussed. In particular, on titania supported gold, where particles of metallic nature are presen...

Quantitative volumetric measurements of low temperature CO chemisorption on Au/ZrO2 catalysts and Fourier transform infrared measurements of adsorbed CO in well defined and controlled conditions of temperature and pressure are here presented as widely accessible and reproducible methods for determining the concentration of gold sites able to chemis...

FTIR absorption spectra of CO, of 12CO–13CO isotopic mixtures and of CO–18O2 interaction on gold catalysts supported on group IV oxides are reported together with CO quantitative chemisorption data. On Au/TiO2 two kinds of metallic gold surface sites, mutually interacting, adsorb CO in spite of the low CO/Au ratio (0.03). On Au/ZrO2, where a CO/Au...

Nanosized gold catalysts supported on doped ceria were prepared by deposition–precipitation method. A deep characterization study by HRTEM/EDS, XRD, FT-Raman, TPR and FTIR was undergone in order to investigate the effect of ceria modification by various cations (Sm3+, La3+ and Zn2+) on structural and redox properties of gold catalysts. Doping of ce...

Mono- and bimetallic palladium–gold catalysts supported on zirconia and ceria, both sulfated and nonsulfated, are tested for the direct synthesis of hydrogen peroxide under very mild (1 bar and 20 ◦C) and non-explosive conditions. Catalysts are characterized by N2 physisorption, sulfur content analysis, temperature programmed reduction (TPR), Fouri...

The physicochemical properties and catalytic performance in the preferential CO oxidation (PROX) reaction of nanosized gold supported on doped-ceria were investigated. Zn- and Sm-doped Au/ceria catalysts were found to be more active than undoped Au/ceria, whereas the addition of lanthanum oxide had the opposite effect. A reductive pretreatment at 3...

Gold-loaded zirconia and sulfated zirconia catalysts were tested in the low-temperature water gas shift reaction. The samples were characterized by N2 adsorption analysis, temperature-programmed reduction, X-ray diffraction, pulse-flow CO chemisorption, FTIR spectroscopy, and high-resolution transmission electron microscopy. A reference catalyst, A...

New gold catalysts supported on mixed CeO 2 -TiO 2 with different ceria loading have been prepared. BET, HRTEM and FTIR characterization has been carried out to reveal the effect of ceria on the WGS and PROX activity.

An FTIR study of CO adsorption from 120 K up to room temperature on a series of Au–ceria samples is presented. Samples with low gold content (0.7 and 0.6 at%) were prepared by urea gelation/co-precipitation and by cyanide leaching of the high-gold content (5.8 at%) material prepared by deposition–precipitation on La-doped CeO2. The samples were sub...

Nano-sized mixed CeO2-TiO2 materials were synthe-sized and then used as supports for preparation of new gold cata-lysts by deposition-precipitation method. In order to get an inter-pretation of the effect of ceria, detailed characterisation by means of high-resolution transmission electron microscopy (HRTEM) and FTIR spectroscopy and catalytic acti...

Fourier transform infrared spectra of CO adsorption from 120 K up to room temperature on two gold catalysts supported on different mixed ceria-titania oxides are discussed in comparison with those obtained on Au/TiO(2) and Au/Fe(2)O(3) reference catalysts provided by the World Gold Council. The spectra of adsorbed CO, run on the different samples b...

A new gold catalyst was synthesized by deposition-precipitation of gold hydroxide on thoria. The catalyst showed extremely high catalytic activity at the lowest possible temperature for carrying out of water-gas shift reaction (WGSR) under experimental conditions. The measured degree of CO conversion at 393 K (GHSV = 4000 h−1) was 84%. The effect o...

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...

The water-gas shift (WGS) activity of different M/ceria catalysts, where M is a metal from 113 group (i.e. Art, Ag, Cu) has been studied. Two different techniques were used for the preparation of the catalysts-deposition-precipitation and a modified version of deposition-precipitation. HRTEM combined with EDS, X-ray diffraction, FT-IR of the molecu...

The effect of the support on the HRTEM features and on the FTIR spectra of adsorbed CO at 90 and 300 K of Au/TiO2, Au/ZrO2 and Au/CeO2, both oxidised and reduced, has been examined. All catalysts have been prepared by the deposition-precipitation method. The aim of this work is to obtain information on the surface structure of the three catalysts i...

A comparative study of CO adsorption on nanosized Au, Ag and Cu supported on ceria has been performed. HRTEM images combined with EDS analysis have shown presence of highly dispersed metallic particles on the surface of the catalysts. FTIR results indicate that IB metals cause a strong modification of the surface properties of ceria, which leads to...

The effects of ZrO2 content on the CO oxidation activity in a series of CuOx/CexZr1−xO2 (x=0, 0.15, 0.5, 0.7 and 1) catalysts were investigated, both in the absence and in the presence of H2, i.e. preferential CO oxidation—PROX. The investigation was performed under light-off conditions to focus the effects of transients and shut-down/start-up cycl...

Different cobalt containing materials obtained from the thermal decomposition of two organic precursors, cobalt–acetylacetonate and cobalt–tetrametoxyphenylporphyrin, and Co3O4 prepared by thermal decomposition of cobalt carbonate have been characterised by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and high resolution transmission m...

Methanol decomposition and methanol combined reforming to hydrogen have been studied by in situ FTIR spectroscopy and quadrupole mass spectrometry (QMS) on Cu and Au catalysts supported on ZnO and TiO2 at increasing temperatures. Methoxy species on ZnO and TiO2 supported catalysts are produced by the reaction of methanol with OH surface groups alre...

A FTIR study of the CO oxidation on Au/ZnO from 90 to 300K in the absence and in the presence of hydrogen has been performed. An insight on the origin of deactivation during CO oxidation at room temperature and on the regeneration effect of hydrogen is given. FTIR spectra show that at 90K only carbonylic species on the metallic particles and on the...

Gold/ceria catalysts were prepared by two different methods (deposition-precipitation and modified deposition-precipitation). Considerable differences in the low-temperature water-gas shift (WGS) activity of both catalysts were observed. The preparation technique strongly influenced catalytic activity due to the large differences in gold particles...

Chemisorption and reactivity of the molecules involved in the water-gas shift (WGS) reaction on gold/ceria catalyst have been studied at 90 and 300 K by FTIR spectroscopy. Forward and reverse WGS reaction at 300 K and up to 573 K have been investigated, too. The FTIR results show that gold causes a strong modification of the surface properties of t...

A FTIR study at low temperature on nanosized gold dispersed on ZrO2 and on TiO2 has been performed. The average size of gold particles (4.1 ± 0.5 nm) is the same on both the supports, nevertheless CO and O2 adsorption and interactions evidenced some differences between the two samples. At 90 K, the absorption bands of CO adsorbed on gold fall at th...

The interaction of methanol (m), methanol–water (mw) and methanol–water–oxygen (mwo) on Au/TiO2 catalyst has been investigated by in situ infrared spectroscopy (FTIR) and quadrupole mass spectrometry (QMS) at different temperatures. The aim of the work is to elucidate the nature and the abundance of the surface intermediates formed in different exp...

A catalytic study of the hydrogen production by CO water gas shift reaction (WGSR) on gold, silver and copper particles supported on TiO2 has been carried out. A deep characterisation of the catalysts by TPR and FTIR has been performed. Silver catalyst exhibits no catalytic activity, copper and gold catalysts show intermediate and very high perform...

The effects of the equilibrium pressure and of the temperature on the FTIR spectra of CO adsorbed on a nanostructured Au/TiO2 catalyst are discussed. At 90 K, at full coverage, in addition to strong bands assigned to CO adsorbed on Ti4+ cations at usual frequencies, a band related to CO adsorbed on gold sites, significantly red shifted in respect t...

The catalytic activity and stability of Au/TiO2 have been examined under ambient conditions. The best performance was obtained for a catalyst calcined at 473K and left at room temperature for a few days. The activity for CO oxidation was greatly influenced by moisture in the reactant gas and a maximum was observed at around 200ppm. We have also suc...

Infrared spectra of CO adsorbed on nanometric gold particles supported on different supports, both oxidised and reduced, are reported. Depending on the nature of the supports, on the pretreatments and on the size of the gold nanoparticles, different gold carbonylic species have been evidenced. The electronic and structural properties of gold nanopa...

Three Au/TiO2 catalysts, with the same Au loading and with different particle sizes, were prepared by the deposition–precipitation method followed by calcination at three different temperatures, 473, 573, and 873 K. The mean diameters of Au particles were 2.4, 2.5, and 10.6 nm, respectively. On all the samples the CO adsorption and different CO–O2...

An FTIR study of CO adsorption and oxidation at 90 K on gold–titania catalysts is presented, concerning three nanostructured Au/TiO2 catalysts, with the same gold loading, calcined at three different temperatures and with different gold particle mean sizes of 2.4, 2.5 and 10.6 nm. On all the samples, the CO adsorption and different CO–18O2 interact...

An FTIR study of CO adsorption and oxidation on Au/TiO2 is reported. At 90 K different CO−18O2 interactions have been performed, with preadsorbed carbon monoxide or preadsorbed isotopically labeled oxygen, with dry or wet carbon monoxide. From the experimental results it can be inferred that (i) at 90 K carbon monoxide and oxygen are molecularly ad...

Nitrous oxide decomposition studies on an Ru/ZrO2 catalyst (activated by oxidation or reduction at 623 and 773 K) have been performed in a flow reactor at 1 atm total pressure. The reaction onset temperature is 573 K, while a complete conversion of reactant is achieved at 773 K. At a given temperature, the oxidized sample exhibits higher conversion...

The Ru/ZrO2 catalyst's surface properties have been studied by quantitative chemisorption experiments on carbon monoxide and oxygen at different temperatures, by FTIR studies of oxygen, carbon monoxide, and nitric oxide adsorptions, and by FTIR studies of the CO–NO reaction. On the oxidized sample at least three FTIR absorptions are evident at 1008...

Infrared spectra of CO adsorbed on nanometric gold particles supported on oxidised and reduced TiO2 are reported. Depending on which pre-treatment is used different stretching bands related to gold carbonyls have been found. On calcined samples the predominant absorption band is at 2110–2120 cm−1, assigned to CO adsorbed linearly on nanometric gold...

Nitrous oxide decomposition studies on an Ru/ZrOâ catalyst (activated by oxidation or reduction at 623 and 773 K) have been performed in a flow reactor at 1 atm total pressure. The reaction onset temperature is 573 K, while a complete conversion of reactant is achieved at 773 K. At a given temperature, the oxidized sample exhibits higher conversion...

An FTIR and quadrupole mass spectroscopic study of the water– gas shift (WGS), the reverse WGS reactions, and the adsorption of the individual molecules involved has been carried out on Au/Fe 2 O 3 and Au/TiO 2 catalysts. The chemisorptions and the reactions on the two catalysts have been compared with the aim of gaining a bet-ter understanding of...

8% Cu/SiO2 and Cu/SiO2–TiO2 catalysts, prepared by the chemisorption hydrolysis method and characterised in the preceding paper (Boccuzzi et al., 1999, J. Catal., 184, 316–326) have been tested in the oxidative coupling of 2,6-dimethylphenol, a well-known copper catalysed reaction in the homogeneous phase. All of them proved to be active after redu...

Three 8 wt% copper catalysts supported on SiO{sub 2} and on two SiO{sub 2}/TiO{sub 2} powders with different TiO{sub 2} content have been prepared by a chemisorption-hydrolysis method. Transmission electron microscopy indicated that after calcination the three catalysts contain supported particles which are small and quite homogeneous in size (mean...

A Fourier transform infrared (FTIR), UV−vis, and high-resolution transmission electron microscopy (HRTEM) study of fresh and used Au/ZrO2 catalyst is reported. FTIR data show that on a fresh sample CO is adsorbed on regular gold metallic sites, while on the used sample the adsorption sites are bidimensional gold clusters made positive by interactio...

A FTIR study of CO adsorbed on and on some bimetallic samples, prepared with different methods, subjected to different pretreatments and to oxidation with O2 is reported. CO adsorption at 298 K on produces a band at 2110–2118 cm−1 that is reversible upon outgassing at room temperature, while on the adsorption of CO produces an absorption band at 20...

The surface activity of a Fe-K/ZrO{sub 2} sample prepared from iron citrate and potassium carbonate has been investigated by the FTIR spectroscopy of adsorbed CO and NO and compared with the behavior of a Fe/ZrO{sub 2} Sample. The addition of potassium produces a strong decrease of the BET area and of the amounts of the adsorbed molecules. At the s...

Different techniques have been used to characterize Cu/TiO 2 (Degussa P-25) catalysts with copper loadings of 2, 4, and 8 wt% Cu, prepared by wet impregnation (labeled I) or by chemisorption– hydrolysis (labeled C). X-ray diffraction patterns of the 8% I sample show, before calcination, the diffraction lines of the monoclinic mod-ification of Cu 2...

The hydrogenation of 1,3-cyclooctadiene and the CO-NO reaction have been studied on Cu/TiO{sub 2} catalysts, with reference to the effects of the preparation method and of the reductive pretreatments of the samples. In the hydrogenation of 1,3-cyclooctadiene at 433 K, a marked difference in activity is observed between catalysts prepared by a chemi...

The curve fitting analysis of the FTIR spectra of two differently pretreated PtZnO dispersed samples is discussed. Carbon monoxide adsorbed on a photodeposited PtZnO sample mildly reduced in a 0.5% H2N2 mixture at 493 K shows a main band at 2100 cm−1, shifting to the red and reducing its intensity by decreasing the surface coverage. All the spectra...

The Fe/ZrO2 catalyst (1% Fe by weight) shows a strong adsorption capacity toward the nitric oxide (at room temperature the ratio NOFe is ca. 0.5) as a consequence of the formation of a highly dispersed iron phase after reduction at 500–773 K. Nitric oxide is adsorbed mainly as nitrosyl species on the reduced surface where the Fe2+ sites are prevail...

An FTIR and quadrupole mass spectroscopic study of CO adsorption and oxidation with {sup 16}O{sub 2} and {sup 18}O{sub 2} is presented together with coadsorption experiments of CO and water on gold supported on ZnO and TiO{sub 2}. The experimental results are closely related to those presented in the parallel paper on copper catalysts supported on...

The activity of Rh supported on the ceria doped titania was investigated by FTIR technique using CO and NO adsorption. The addition of ceria does not lead to new adsorbed species: however the difficult reduction at 500 K of chloride ions of impregnated Rh salt and the persistence of Rh1 + sites until 773 K are the fingerprints of the effects of cer...

The activity of Rh supported on the ceria doped titania was investigated by FTIR technique using CO and NO adsorption. The addition of ceria does not lead to new adsorbed species: however the difficult reduction at 500 K of chloride ions of impregnated Rh salt and the persistence of Rh1+ sites until 773 K are the fingerprints of the effects of ceri...

Pd–Fe/SiO2 bimetallic catalysts, prepared by sequential wet impregnation, with a constant 2 wt.% Pd loading and with atomic ratios Fe/Pd = 0.5–2.1, and monometallic samples have been studied by quantitative chemisorption and by FTIR spectroscopy of adsorbed CO and NO. The FTIR results indicate that on the examined bimetallic samples CO is selective...

An FTIR and quadrupole mass study of the adsorption and oxidation of CO on an Au/ZnO sample with 16O2 and 18O2 is presented. The results indicate that CO adsorbed on gold sites at the perimeter interface with ZnO reacts with surface lattice oxygens at the oxide surface to form carbonate-like intermediates. This reaction and the decomposition of the...

Pd-Fe/SiO2 bimetallic catalysts with a constant amount of Pd and a different Fe/Pd ratio were prepared by sequential wet impregnation and the hydrogenation of 2,4-dinitrotoluene was carried out at 25°C in a batch reactor. The presence of Fe enhances the Pd catalytic activity. The formation of a dispersed Pd-Fe alloy was evidenced through X-ray pow...

The adsorption and oxidation of ammonia, trimethylamine and and nitric oxide on Ru/TiO2 and TiO2 have been studied by FTIR spectroscopy. On both the samples ammonia and trimethylamine are adsorbed at room temperature molecularly on the surface Ti4+ sites. By heating ammonia at T>473 K, wate and hydroxyls are produced. The oxidation at 473 K of the...

Characterization by high-resolution transmission electron microscopy of differently pretreated Cu/TiO[sub 2] samples and IR and mass spectroscopic studies of NO-CO interaction on them from room temperature to 473 K are presented. All samples are characterized by Cu particles well dispersed on TiO[sub 2] surface. The adsorption of CO produces an abs...

An FTIR and quadrupole mass study of CO adsorption and oxidation with16O2 and18O2 on Au/ZnO catalysts is presented. The experimental results indicate that: (i) CO is activated by gold in two molecular forms, a linear carbonyl species bonded at terrace Au sites and a carbonyl species bonded to Au peripheral sites; (ii) a band related to CO adsorbed...

FTIR study of CO adsorption on Au/TiO2 samples prepared by a deposition -precipitation technique is presented. The absorption spectra of 12 CO and 12 CO - 13 CO mixture are examined at different equilibrium pressures at room temperature. From these data two kinds of chemically active sites, strongly coupled and interacting were evidenced. Chemical...

The interaction of ethylene with a highly dispersed and oxidized Ru/ZnO catalyst has been studied at room temperature (RT) by FTIR spectroscopy. A fast oxidative reaction at RT produces a glycolate-like species strongly adsorbed on the surface, and at the same time the depletion of a strong and narrow band assigned to an RuO surface group. The ass...

Ru/MgO, Cu/MgO, and Ru-Cu/MgO systems were characterized by FT-IR spectroscopy of adsorbed CO. The systems studied contained a total amount of metal of about 2 wt %: RCM100, RCM083, RCM070, RCM046, RCM034, and RCM000, with Ru/(Cu + Ru) atomic ratios 1, 0.83, 0.70, 0.46, 0.34, and 0.00, respectively. A comparison was made between the spectroscopic r...

A comparative study of the surface properties of Cu-Ti samples prepared by impregnation of TiO2 with a Cu(NO3)2 solution or from amorphous CuTi alloy precursors diluted with TiO2 has been made. The samples were submitted to vacuum and H2 treatments at increasing temperatures, from 493 up to 773 K; at the end of the pretreatments the specimens were...

The adsorption of NO and the interaction of NO-CO mixtures on Ru/ZnO has been studied by FTIR and mass spectroscopic experiments. NO is adsorbed initially on Ru[sup 0] and Ru[sup 2-] surface sites present on the reduced catalyst; however, a slow NO dissociation process leads to NO species adsorbed on more oxidized Ru[sup 3+] sites and to NO[sub 2][...

A FT-IR spectroscopic study has been made on two ZnO powders differently prepared: one obtained by thermal decomposition of ZnCO3 (ex-C), the other by zinc metal combustion (Kadox). The morphological differences between the samples have been proposed to be at the origin of the different reactivity and electronic phenomena. In particular, on the mor...

We report the adsorption and the deuteration of acetone-d6 on differently pretreated Pt/ZnO catalysts, studied by FTIR. On mildly reduced samples the deuteroacetone is mainly adsorbed at room temperature (RT) in molecular end-on forms; upon heating at 373 K minor amounts of CO are formed. These findings indicate that the adsorption on the mildly re...

NO adsorption on differently pretreated pure ZnO and Pt/ZnO samples has been investigated by FTIR spectroscopy. Both the vibrational modes of the adsorbed species and the changes in the IR transmission of samples are discussed. On mildly reduced Pt/ZnO samples NO is adsorbed molecularly on Pt sites, while on pure ZnO nitrite and nitrate species are...

An FTIR study of the NO-CO interaction, from RT up to 533 K, was done on two differently pretreated Pt/ZnO samples: the first, mildly reduced, formed of small pure Pt particles dispersed on ZnO, and the second, strongly reduced, presenting PtZn alloyed metal particles. On the mildly reduced one by heating in NO-CO atmosphere at 373 K a quite strong...

The interaction with NO of differently pretreated ZnO and TiO2 pressed powders, pure or modified by noble metal addition (Pt and Ru, respectively) is studied, mainly by FT-IR spectroscopy; the analysis of the IR spectra concerns both the vibrational modes of the absorbed species and the variations of the IR transparency related to changes in the el...

The adsorption of trimethylamine (TMA) at room temperature (RT) and its oxidative interaction on TiO2 and until 773 K has been studied by FTIR. TMA is molecularly chemisorbed on the coordinatively unsaturated (eus) Ti4+ Lewis centers of the support at RT and is only slowly oxidized at this temperature. A first oxidation, leading to dimethylformamid...

The importance of the metal-support interaction on the catalytic properties of an oxide-supported metal has been shown by a great number of experimental data. Structural, chemical and electronic interactions are all very important to realize the catalyst configuration responsible for its high reactivity and/or selectivity. Furthermore the interacti...

SnO2 samples submitted to thermal treatments in vacuo and O2 show strong modification both in shape and position of the valence band-conduction band (VB-CB) absorption edge, its stoichiometry being seriously perturbed. Interaction with pure NO at room temperature (RT) originates a set of surface reactions: a reversible one related to a reversible r...

NO adsorption on differently pretreated pure TiO2 and Ru/TiO2 samples has been investigated using FTIR spectroscopy. The analysis of the IR spectra concerns both the variations of the IR transparency, related to the electronic properties of the samples, and the vibrational modes of the adsorbed species.The experimental results are discussed taking...

The nature and stability of chromium species on the surface of CrOx/ZrO2 catalyst (Cr content 1.6 wt%) have been investigated using IR spectroscopy. On a sample heated in O2 at 923 K, Cr is present on the surface as Cr(V) (both as mononuclear and polynuclear chromyl species), and as Cr(VI) (both as chromates and polychromates). Upon reduction with...

A comparative spectroscopic study has been made of two ZnO powders coming from zinc carbonate decomposition (ex-carbonate) and from zinc metal combustion (Kadox). The morphological differences between the samples have been found to be at the origin of their different reactivity. In particular, on the more perfect, lower surface area Kadox microcrys...