Applied Catalysis A, General (v.353, #1)

Contents (iii-viii).

Vapor phase nitration of toluene with nitric acid over H3PO4/ZSM-5-surf-170 (2.1 wt.% P) has been investigated. In this reaction, 4-nitro toluene was found to be the major product when 2-nitro toluene was very negligible in the product stream; 3-NT was not detected and oxidation products were trace.▪The nitration of toluene has been studied in the vapor phase at various temperatures over a series of surface modified and unmodified ZSM-5 (Si/Al = 170) loaded with H3PO4, differing in the external surface treatment of the zeolites. All samples were characterized by X-ray diffraction, BET and FT-IR. The nature of acid sites of the supports, i.e., H3PO4/ZSM-5-surf-170 and H3PO4/ZSM-5-170 was determined using FT-IR-pyridine adsorption study. 2,4,6-Trimethyl pyridine adsorption was used for calculating the external surface acidity of the H3PO4/ZSM-5-surf-170 and H3PO4/ZSM-5-170. The superior performance of the externally blocked catalysts (modified) relevant to the H3PO4/ZSM-5-170 catalyst shows that by blocking the external surface area of the ZSM-5 support, it exhibits a superior catalytic selectivity than the unmodified catalyst. Catalysts containing 0–4.9 wt.% P were prepared using ZSM-5-surf-170 and ZSM-5-170, and their catalytic performance was determined for the vapor phase nitration of toluene to 4-nitrotoluene (4-NT), 2-nitrotoluene (2-NT) and oxidation products. The effect of reaction temperature, H3PO4 content, feed ratio of toluene to HNO3, WHSV, TOS and carrier gas flow rate was also investigated.
Keywords: Vapor phase; Nitration; Cationic surfactant; H3PO4; Modified ZSM-5; Toluene; 4-Nitrotoluene;

The knowledge of kinetics of hydrogen peroxide reduction by hydrogen is required as a part of complete kinetics of H2O2 formation by direct combination of hydrogen and oxygen, which involves synthesis, reduction, and decomposition of H2O2, as well as synthesis of water. A mechanism of hydrogen peroxide reduction was proposed. A rate expression based on this mechanism was shown to accurately correlate experimental data over wide ranges of reactant concentrations and temperature.▪An overall rate expression for the formation of hydrogen peroxide by direct combination (DC) of H2 and O2 is required for a rational design of a microreactor and for the determination of the optimum operating conditions for this process. Since the formation of H2O2 by the DC process involves four simultaneous reactions (synthesis of H2O2, synthesis of water, decomposition of H2O2, and reduction of H2O2 by H2), the overall rate expression must take into account the rate expressions of these reactions. In this work, we investigate the mechanism and the rate expression for reduction of H2O2 by H2. Kinetic experiments were carried out to measure the effects of H2O2 concentration and H2 partial pressure on the rate of reaction. The reaction was shown to be free of mass transfer limitations at the conditions of the kinetic experiments. A Langmuir-Hinshelwood mechanism for the reduction of H2O2 over Pd/SiO2 catalyst was adopted since the simple power-law expression could not explain the obtained kinetic data. A rate expression based on this mechanism was shown to accurately correlate experimental data over a wide range of H2O2 concentration, H2 partial pressure, and temperature.
Keywords: Hydrogen peroxide; Direct synthesis; Microreactor; Palladium catalyst; Reduction; Sulfuric acid; Kinetics; Catalysis; Multiphase reactors;

LCO hydrotreating with Mo-Ni and W-Ni supported on nano- and micro-sized zeolite beta by Lianhui Ding; Ying Zheng; Hong Yang; Rahimi Parviz (17-23).
The effect of zeolite beta particle size on the HDS, HDN, and HDA activities of LCO hydrotreating was investigated on Mo-Ni and W-Ni supported on nano- and micro-sized zeolite beta hydrotreating catalysts. The catalysts were characterized by XRD, BET, TEM, and XPS, and evaluated with an autoclave using real LCO as feed. It was concluded that, with the Mo-Ni catalysts, the catalyst containing nano-sized zeolite beta particles had similar hydrogenation activity as the one containing micro-sized (conventional) particles; with the W-Ni catalyst, the nano-sized zeolite catalyst presented higher HDS, HDN, and HDA activities as expected. Higher liquid yields could be achieved by using the W-Ni and Mo-Ni nano-sized zeolite catalysts.▪The effect of zeolite beta particle size on the HDS, HDN, and HDA activities of LCO hydrotreating was investigated on Mo-Ni and W-Ni supported on nano- and micro-sized zeolite beta hydrotreating catalysts. The catalysts were characterized by XRD, BET, TEM, and XPS, and evaluated with an autoclave using real LCO as feed. It was concluded that, with the Mo-Ni catalysts, the catalyst containing nano-sized zeolite beta particles had similar hydrogenation activity as the one containing micro-sized (conventional) particles; with the W-Ni catalyst, the nano-sized zeolite catalyst presented higher HDS, HDN, and HDA activities as expected. Higher liquid yields could be achieved by using the W-Ni and Mo-Ni nano-sized zeolite catalysts.
Keywords: Nano-sized zeolite; Zeolite beta; Hydrotreating; LCO;

The reaction pathways for selective oxidation of propane to acrolein on Ce0.1Ag0.3Mo0.5P0.3O x catalyst were investigated by three methods, (i) steady-state reaction test of the individual oxidation of propane and the probe molecule of possible reaction intermediates, (ii) temperature-programmed surface reaction (TPSR) study of propane oxidation in presence of gas phase O2 or not, and (iii) in situ Raman spectroscopy investigation of propane oxidation and propylene oxidation on the catalyst. Based on the obtained results, three possible reaction pathways for selective oxidation of propane to acrolein on the catalysts are proposed. The major reaction pathway is that propylene (π-allyl species) is produced from the activation of the methylene C–H bond of propane and further oxidizes to acrolein through σ-allyl species. However, the presence of gas phase O2 favors the formation of acrolein in propane oxidation on the catalyst.Three possible reaction pathways for selective oxidation of propane over Ce0.1Ag0.3Mo0.5P0.3O x catalyst are proposed. Path II is the major reaction pathway in which propylene (π-allyl species) is produced from the activation of the methylene C–H bond of propane and further oxidizes to acrolein through σ-allyl species on the catalyst.▪
Keywords: Selective oxidation; Propane; Acrolein; Intermediate; Reaction pathways;

The cross-metathesis of fatty acid methyl esters with allyl chloride under bulk conditions was investigated with second generation ruthenium olefin metathesis catalysts revealing that important α,ω-difunctional chemical intermediates can thus be obtained from renewable resources in an efficient catalytic reaction.▪The synthesis of α,ω-difunctional chemical intermediates from renewable resources via the cross-metathesis reactions with allyl chloride is described. Different ruthenium metathesis catalysts were investigated and the reaction conditions were optimized for high conversions in combination with high cross-metathesis selectivity. New building blocks and chemical intermediates from fatty acid derivates were thus obtained in catalytic reactions with low catalyst loadings under bulk conditions. Therefore, a new potential use of renewable raw materials for the synthesis of intermediates for Nylon-11 and Nylon-12 was demonstrated.
Keywords: Olefin metathesis; Cross-metathesis; Renewable resources; Monomer; Fatty acid; Nylon;

High throughput cell for X-ray absorption spectroscopy applied to study the effect of Au on Rh-catalyzed partial oxidation of methane by Bertram Kimmerle; Peter Haider; Jan-Dierk Grunwaldt; Alfons Baiker; Pit Boye; Christian G. Schroer (36-45).
The effect of gold addition, metal loading and preparation route of alumina-supported rhodium catalysts on their catalytic behavior in the partial oxidation of methane is studied in a parallel in situ X-ray absorption spectroscopy (XAS) cell designed for simultaneous catalytic and structural investigation of six catalysts under different feed gas conditions. Potential and limitations of the high throughput XAS cell are discussed. ▪A parallel reactor cell for catalytic in situ X-ray absorption spectroscopy (XAS) measurements was developed. The cell facilitates the simultaneous catalytic and structural investigation of six catalysts under different feed gas conditions. A two-dimensional X-ray sensor was used for spectra collection. Gas compositions were measured by on-line mass spectrometry. The potential and limitations of the high throughput XAS cell are discussed. The heterogeneously catalyzed partial oxidation of methane (CPO) was chosen as a test reaction. Alumina-supported Rh and Au/Rh catalysts with different metal loadings (0.5–2.5 wt%) were applied and prepared via different preparation routes using flame spray pyrolysis (fsp) and colloid adsorption (col). For comparison the same catalysts were also investigated in a fixed-bed capillary reactor heated by a gas blower (also for XAS measurements) and in an eight-fold parallel gas phase reactor using similar reaction conditions (6% CH4–3% O2–He, 250–500 °C). Similar catalytic results were obtained in all three reactor types, confirming the suitability of the parallel reactor XAS cell for catalytic measurements. The catalysts showed different activity, selectivity and reducibility depending on metal loading, preparation route and Au/Rh ratio. The analysis of the catalytic data, STEM images and the in situ XANES experiments of the various catalysts indicated the following characteristics for the CPO reaction: sufficient heat production by combustion of methane, total conversion of oxygen, and reduction of a certain fraction of the catalyst. The overall catalytic behavior was in line with a two-zone model of the catalyst bed where catalytic combustion dominates in the front zone and reforming reactions become favored in the second part of the catalyst bed.
Keywords: X-ray absorption spectroscopy; High throughput technology; In situ spectroscopy; Partial oxidation of methane; Gold; Rhodium; Alumina; Flame spray pyrolysis;

The transformation of benzofuran, 2,3-dihydrobenzofuran and 2-ethylphenol, as well as the competitive effect between furanic and phenolic compounds over NiMoP/Al2O3 were studied under a total pressure of 7 MPa at 340 °C in a fixed bed reactor with or without H2S. Ethylcyclohexane was already the main deoxygenated product. A promoting effect of H2S on the deoxygenating rate of all oxygenated compounds was observed.▪The transformation of benzofuran, 2,3-dihydrobenzofuran and 2-ethylphenol, as well as the competitive effect between furanic compounds (benzofuran and 2,3-dihydrobenzofuran) and a phenolic compound (2-propylphenol) over a sulfided NiMoP/Al2O3 catalyst were studied under a total pressure of 7 MPa at 340 °C in a fixed bed reactor. The transformation of each oxygenated compounds was carried out with or without H2S (from dimethyldisulfide). Ethylcyclohexane was already the main deoxygenated product which was obtained by hydrogenation of aromatic ring followed by dehydratation and hydrogenation reactions (HYD pathway). The formation of ethylbenzene by a direct deoxygenation (DDO) pathway was in all cases very limited. Other oxygenated products were obtained by disproportionation and isomerization reactions. A global reaction scheme of the benzofuran transformation over a NiMoP/Al2O3 sulfided catalyst was established. In addition, the inhibiting effect of benzofuran and/or 2,3-dihydrobenzofuran on the transformation of 2-ethylphenol was demonstrated. Moreover, a promoting effect of H2S on the deoxygenating rate of all oxygenated compounds was observed.
Keywords: Hydrodeoxygenation; NiMoP/Al2O3; Benzofuran; 2,3-Dihydrobenzofuran; 2-Ethylphenol; H2S;

Titanium (IV) oxide in anatase form showed a very good catalytic activity and selectivity for the preparation of azoxybenzenes from arylamines. Catalytic activity can be regenerated with virtually no loss of its activity. ▪The titanium (IV) oxide is used as the catalyst in the heterogeneous liquid phase reaction for the oxidation of aniline and substituted anilines using dilute hydrogen peroxide as an oxidizing agent with different solvent conditions. Titanium (IV) oxide samples have been prepared under different experimental conditions by the sol–gel method. Experimental data showed that anatase form was an efficient catalyst for the title reaction and exhibited excellent selectivity (100%) and good yield (>90%) for the oxidation of aniline and substituted anilines, whereas the rutile form was found to be totally inactive. A high percentage of selectivity and good yields were achieved under mild reaction conditions. The recovered catalyst was used several times for the oxidation reaction with virtually no loss of activity. Overall a good catalytic activity and structure relationship was observed.
Keywords: Selective oxidation; Anilines; Azoxybenzenes; Anatase; Rutile; Hydrogen peroxide; Titanium (IV) peroxo species;

Highly efficient oxidation of sulfides with sodium periodate catalyzed by reusable silica supported Mn(Br8TPP)Cl and Mn(TPP)Cl catalysts under various reaction conditions by Valiollah Mirkhani; Majid Moghadam; Shahram Tangestaninejad; Iraj Mohammdpoor-Baltork; Hadi Kargar; Mehdi Araghi (61-67).
Silica supported manganese (III) were used as heterogeneous catalysts for biomimetic oxidation of sulfides with NaIO4 under agitation with magnetic stirring and under ultrasonic (US) irradiation and sulfoxides and sulfones were obtained as products in high to excellent yields. These new heterogenized catalysts could be reused several times without significant loss of their catalytic activity.▪Silica supported octabromotetraphenylporphyrinatomanganese (III) chloride, Mn(Br8TPP)Cl-SiIm, and tetraphenylporphyrinatomangenese (III) chloride, Mn(TPP)Cl-SiIm were used as heterogeneous catalysts for biomimetic oxidation of sulfides with NaIO4 under agitation with magnetic stirring and sulfoxides and sulfones were obtained as products in high to excellent yields. Ultrasonic irradiation enhanced the catalytic activity of these catalysts in the oxidation of sulfides, reduced the reaction times and increased the product yields. Linear sulfides were completely converted to sulfones while aromatic and cyclic sulfides produced the sulfoxide and sulfone. These new heterogenized catalysts could be reused several times without significant loss of their catalytic activity.
Keywords: Sulfide; Periodate; Sulfoxide; Sulfone; Metalloporphyrin;

H4SiW12O40/SiO2 shows high activity and selectivity for preferential oligomerization of isobutene in a mixture of isobutene and 1-butene. Here selectivity is defined as the fraction of isobutene converted against the total conversion.▪Preferential oligomerization of isobutene in a mixture of isobutene and 1-butene (molar ratio of 1:1) over H4SiW12O40/SiO2 was investigated with different loadings of H4SiW12O40. The catalytic performance of H4SiW12O40/SiO2 was compared with those of typical solid acids, such as H-β, SiO2-Al2O3, and SO4 2−/ZrO2. H4SiW12O40/SiO2 was superior in activity and selectivity for isobutene oligomerization (defined as the fraction of isobutene converted against the total conversion) compared to other catalysts. The activity was sensitive to the H4SiW12O40 loading on SiO2, reaching a maximum at around 40 wt.%, due to the change in the acid amount of the outermost surface as determined by temperature-programmed desorption of benzonitrile. The selectivity for isobutene oligomerization also changed with the H4SiW12O40 loading. The highest selectivity (∼95%) was achieved using 10 wt.% H4SiW12O40/SiO2 at 293 K, due to the absence of strong acid sites on the outermost surface. In the conversion of linear butene (1- and 2-butene), an induction period occurred when 10 wt.% H4SiW12O40/SiO2 was used, because linear butene cannot adsorb on the acid sites when isobutene is present in the reaction mixture.
Keywords: Supported heteropolyacid; Isobutene; Linear butene; Oligomerization; Solid acid; Surface acidity;

Solid heteropoly acid supported on silica gel (Cu3/2PMo12O40/SiO2) is easily used as a heterogonous, reusable and efficient catalyst for synthesis of 2-arylbenzimidazoles and 2-arylbenzothiazoles by reaction of o-phenylenediamine and o-aminothiophenol with different aldehydes under various conditions. The catalyst can be reused for several times but it will be less active.▪Solid heteropoly acid supported on silica gel (Cu3/2PMo12O40/SiO2) is easily used as a heterogonous, reusable and efficient catalyst for synthesis of 2-arylbenzimidazoles and 2-arylbenzothiazoles by reaction of o-phenylenediamine and o-aminothiophenol with different aldehydes under various conditions (in solvent, under solvent-free conditions, microwave and ultrasonic wave irradiation). The catalyst can be reused for several times but it will be less active.
Keywords: Heteropoly acids (HPAs); Polyoxometalates (POMs); 2-Arylbenzimidazoles; 2-Arylbenzothiazoles; o-Aminothiophenols; o-Phenylenediamine (OPD); Heterogeneous; Supported catalyst;

Manganese complexes of polystyrene-supported poly(amidoamine) dendrimers of three generations (G1–G3) were prepared and characterized. These complexes were found to be efficient and reusable catalysts for the oxidation of secondary alcohols to ketones under mild reaction conditions. The catalyst remained stable under different reaction conditions and with various substrates. A positive dendrimer effect was observed. Oxidation was efficient in the presence of a green oxidant like urea–hydrogen peroxide adduct. The catalyst can be recycled up to six times.▪A novel polymer-supported heterogeneous oxidation catalyst is reported. Manganese complexes of polystyrene-supported poly(amidoamine) dendrimer were prepared, characterized and used as catalysts for oxidation of secondary alcohols. The catalysts showed high stability and efficiency under various reaction conditions and with different substrates. The catalysts can be recycled.
Keywords: Alcohol; Oxidation; Polymer-supported catalyst; Dendrimer; Manganese complex;

Oxidative bromination of methane on silica-supported non-noble metal oxide catalysts by Ronghe Lin; Yunjie Ding; Leifeng Gong; Jingwei Li; Weimiao Chen; Li Yan; Yuan Lu (87-92).
Various silica-supported non-noble metal oxide catalysts were investigated for the oxidative bromination of methane, mediated by HBr/H2O. BaO/SiO2 showed good activity for its lack of facile redox capacity, but suffered deactivation after 30 h. The characterization results implied that aggregation of barium particles occurred, which made the metathesis between BaO and BaBr2 difficult. ▪Oxidative bromination of methane, mediated by HBr/H2O (solution), provides an original route for the production of oxygenates and gasoline directly from natural gas. However, the reported catalysts for this reaction all involved noble metals. From the consideration of replacing noble metal catalysts with cheaper oxides, various silica-supported oxide catalysts were surveyed. It was found that the redox ability of different metals had a strong impact on the product distribution. On the catalysts with metals that lack facile redox ability, such as BaO/SiO2, both CH3Br and CO were main products. Otherwise, deep oxidation proceeded. Moreover, methanol was firstly reported in this system. In order to obtain a molar ratio of (CH3OH + CH3Br): CO = 1, which can provide a perfect feedstock for the synthesis of acetic acid, the process variables were optimized on BaO/SiO2. It was demonstrated that 44.0% methane conversion and 95% total selectivity of CH3Br, CH3OH and CO could be achieved at 620 °C, and the molar ratio of (CH3Br + CH3OH): CO was close to 1. Time-on-stream tests showed declined catalytic performance after 30 h. The results from N2-adsorption, XRF and XRD implied that aggregation of barium particles occurred, making the metathesis between BaO and BaBr2 difficult. The functions of BaO were also proposed. Additionally, the activity data were compared with those of noble metal catalysts.
Keywords: Methane oxidative bromination; Non-noble metal oxide; BaO/SiO2; (CH3OH + CH3Br): CO; Metathesis; Deactivation mechanism;

Effect of Ge content on the metal and acid properties of Pt-Re-Ge/Al2O3-Cl catalysts for naphtha reforming by V.A. Mazzieri; C.L. Pieck; C.R. Vera; J.C. Yori; J.M. Grau (93-100).
The effect of the Ge content on the properties of the metal and acid functions of trimetallic naphtha reforming catalysts of Pt-Re-Ge/Al2O3-Cl was studied. It was found that the addition of small quantities of Ge produce modification of the metal/acid balance an effect over the distribution of products of n-heptane reforming. Both the isomerization activity and the stability of the catalyst were enhanced while the cracking and dehydrocyclization activities were decreased. The isoparaffins/aromatics ratio was improved and as a result the reformate product better adjusted to environmental regulations.▪The effect of the Ge content on the properties of the metal and acid functions of trimetallic naphtha reforming catalysts of platinum-rhenium-germanium supported on chloride alumina was studied. Pt, Re and Ge were loaded using the coimpregnation method. The elemental concentration of the catalysts used was: Pt = Re = 0.3%; Ge = 0.1%, 0.3%, 0.6% and 0.9% (weight basis). In order to make a comparison Pt/Al2O3 and Pt-Re/Al2O3 catalysts were prepared. The properties of the acid and metal functions were studied by physicochemical techniques and using test reactions. Reforming of n-heptane (450 °C, 0.1 MPa, H2/nC7  = 4, WHSV = 7.3) was used to evaluate the catalytic properties of the samples. It was found that the addition of small quantities of Ge (0.1%) decreased both the hydrogenolytic and dehydrogenation activities by breaking Pt-Re ensembles and modifying the electronic density of Pt. The latter was revealed by the decrease in the CO chemisorption capacity and the shift of the bands of linearly adsorbed CO. With respect to the acid function Ge addition produced a change in the acid strength distribution, increasing the amount of mild and weak acid sites and decreasing the amount of strong ones. This modification of the metal/acid balance had an effect over the distribution of products of n-heptane reforming. Both the isomerization activity and the stability of the catalyst were enhanced while the cracking and dehydrocyclization activities were decreased. The isoparaffins/aromatics ratio and the octane gain were improved and as a result the reformate product better adjusted to environmental regulations.
Keywords: n-Heptane reforming; Trimetallic catalysts; Pt-Re-Ge; Ge charge effect on Pt-Re;

Selective hydrogenation of dimethyl adipate on titania-supported RuSn catalysts by Adriana M. Silva; Marco A. Morales; Elisa M. Baggio-Saitovitch; Elizabete Jordão; Marco A. Fraga (101-106).
The hydrogenation of dimethyl adipate over RuSn/TiO2 catalysts was studied to examine the effect of tin species and titania on selective production of 1,6-hexanediol. It was found that the optimal Sn/Ru ratio to reach maximum selectivity changed according to the catalyst reduction temperature. A remarkable selectivity of 70% of 1,6-hexanediol was accomplished over the catalyst with Sn/Ru ratio of 2 and reduced at 400 °C. It was concluded that all systems presented a similar distribution of tin species and no entity revealed to be preferentially formed. The establishment of strong-metal–support interaction and thus a synergistic effect between TiO x moieties and Sn n+ species was suggested to determine the reaction pathway.▪The hydrogenation of dimethyl adipate over RuSn/TiO2 catalysts was studied to examine the effect of tin species and titania on selective production of 1,6-hexanediol. The bimetallic catalysts were prepared by co-impregnation and the reaction was carried out in a liquid phase semi-batch reactor at moderate conditions (255 °C and 50 bar). The optimal Sn/Ru ratio to reach maximum selectivity changed according to the catalyst reduction temperature. A remarkable selectivity of 70% of 1,6-hexanediol was accomplished over the catalyst with Sn/Ru ratio of 2 and reduced at 400 °C. The characterization of the bimetallic catalysts reduced at such a high temperature was performed by Mössbauer spectroscopy and it was found that all systems presented a similar distribution of tin species and no entity revealed to be preferentially formed. The establishment of strong-metal–support interaction and thus a synergistic effect between TiO x moieties and Sn n+ species was suggested to determine the reaction pathway.
Keywords: Dimethyl adipate; 1,6-Hexanediol; Titania; Metal–support interaction; RuSn catalysts; Selective hydrogenation;

Oxidations of cycloalkanes and benzene by hydrogen peroxide catalyzed by an {FeIIIN2S2} centre by Ricardo R. Fernandes; Marina V. Kirillova; José A.L. da Silva; João J.R. Fraústo da Silva; Armando J.L. Pombeiro (107-112).
An iron(III) complex bearing an {FeN2S2} centre was found to act as an efficient catalyst (TONs up to 490) for the oxidation, under mild conditions, of cycloalkanes and benzene by aqueous H2O2 in CH3CN, in the presence of pyrazinecarboxylic acid or nitric acid.▪The ironIII complex [Fe(gma)(PBu3)] [H2(gma) = glyoxal-bis(2-mercaptoanil)], bearing an {FeN2S2} centre, was found to act as a selective catalyst or catalyst precursor towards the oxidation, under mild conditions, of (i) cycloalkanes (cyclopentane and cyclohexane) to the corresponding cyclic alcohols and cyclic ketones, and (ii) benzene to phenol, by aqueous H2O2 in CH3CN and in the presence of pyrazinecarboxylic acid (Hpca) or nitric acid as additives. The system exhibits a good selectivity towards the alcohols (typically ca. 90% upon deoxygenation of the formed cycloalkyl hydroperoxides by PPh3). The influence of various factors, such as temperature, amounts of reagents and reaction time, were investigated in a systematic way, and overall yields of alcohols and ketones up to 17% and of phenol up to 20% were achieved. Catalyst turnover numbers (TONs) of 490, 415 and 110 were obtained in the oxidation of cyclopentane, cyclohexane and phenol, respectively. The turnover frequency (TOF) is comparable with those of alkane monooxygenases. The reactions proceed via both oxygen- and carbon-radicals as shown by experiments with radical traps.
Keywords: Iron catalyst; Hydrogen peroxide; N,S ligands; Alkanes; C–H activation;

Catalytic activity of linear chain ruthenium carbonyl polymer [Ru(CO)4] n in 1-hexene hydroformylation by Larisa Oresmaa; M. Andreina Moreno; Minna Jakonen; Sari Suvanto; Matti Haukka (113-116).
Catalytic activity of the ruthenium carbonyl polymer [Ru(CO)4] n was studied in hydroformylation of 1-hexene. Compared to cluster Ru3(CO)12, the linear chain polymer showed higher activities. A series of potential supports including SiO2, Al2O3, zeolite and multiwalled carbon nanotubes were explored to optimize the catalytic activity and reusability of the catalyst. The highest activities were obtained with [Ru(CO)4] n supported on MWCNT.▪The catalytic activity of the ruthenium carbonyl polymer [Ru(CO)4] n was studied in the hydroformylation of 1-hexene. Compared to the more commonly used ruthenium carbonyl catalyst, Ru3(CO)12, the linear chain polymer showed higher levels of activity. Although [Ru(CO)4] n itself is only sparingly soluble under catalytic conditions and acts as a heterogeneous catalyst on its own, the effects of supports on catalytic activity were also investigated. A series of potential supports including SiO2, Al2O3, zeolite and multiwalled carbon nanotubes (MWCNT) were explored in order to optimize the catalytic preformance and reusability of the catalyst. The highest activities were obtained with MWCNT supported [Ru(CO)4] n . Unlike any of the conventional oxide supports, the MWCNT improved the total catalytic activity in comparison with the unsupported polymer.
Keywords: Ruthenium; Carbonyl; Polymer; Hydroformylation;

Quantitative IR experiments were realized to determine the concentration of cobalt in a form of trivalent cations being in the oxide form as well as divalent ions in exchange positions, oxide-like clusters and cobalt oxide, present in a series of cobalt-exchanged zeolites. We elaborate the experimental conditions in which probe molecules NO and CO should react selectively with either of these sites. The sum of the concentration of Co sites (Co3+ and Co2+) determined by IR spectroscopy was very close to the values obtained from the chemical analysis (AAS).▪Quantitative IR experiments were realized to determine the concentration of cobalt in a form of trivalent cations being in the oxide form as well as divalent ions in exchange positions, oxide-like clusters and cobalt oxide, present in a series of cobalt-exchanged zeolites. The first step of such quantitative studies was to elaborate the experimental conditions in which probe molecules NO and CO should react selectively with either of these sites. Subsequently, the values of absorption coefficients of the 1940 cm−1 band of Co3+–NO and the 2204 cm−1 band of Co2+–CO for Co2+ in exchange positions, together with the 2194 cm−1 band of Co2+–CO for Co2+ in oxide-like clusters were determined. The linear plots of the band intensities versus the concentration of NO and CO interacting with cationic sites showed the correlation coefficients higher than 0.99. Three zeolites were investigated: CoZSM-5 (Si/Al = 15) in which most of Co2+ occupied the exchange positions, CoZSM-5 (Si/Al = 40) in which most of Co2+ was in the form of oxide-like clusters and CoO, and CoFER prepared by the contact-induced ion exchange with nearly equal amount of Co2+ in either type of the sites. The sum of the concentration of Co sites (Co3+ and Co2+) determined by IR spectroscopy was very close to the values obtained from the chemical analysis (AAS). The concentration ill-defined oxide form of Co3+ was surprisingly high as in CoZSM-5 of Si/Al = 15 it constituted about half of the overall cobalt content, and in CoFER the contribution of Co3+ reached almost 30%.
Keywords: CoZSM-5; CoFER; IR spectroscopy; Absorption coefficient;

Effect of phenol addition on the performances of H–Y zeolite during methylcyclohexane transformation by I. Graça; J.-D. Comparot; S. Laforge; P. Magnoux; J.M. Lopes; M.F. Ribeiro; F. Ramôa Ribeiro (123-129).
The transformation of a mixture of methylcyclohexane and a small amount of phenol, as representative of a mixture of bio-oil and Fluid Catalytic Cracking (FCC) feedstock, was studied at various temperatures over a USHY zeolite. At 350 °C, the adsorption of phenol on both Brönsted and Lewis acid sites increases the zeolite deactivation. The increase of the reaction temperature allows limiting the effect of phenol addition on the zeolite activity and stability.▪The transformation of a mixture of methylcyclohexane and a small amount of phenol, as representative of the transformation of a mixture of biomass-derived oxygenates and Fluid Catalytic Cracking (FCC) feedstock was studied at 350 and 450 °C over a USHY zeolite. At 350 °C, the addition of phenol increases the deactivation of the zeolite catalyst, which is due to phenol adsorption on both Brönsted and Lewis acid sites, in addition to the formation of coke from methylcyclohexane. Whatever the contact time and the phenol amount, this deactivation is always partial, which suggests that a substantial portion of the active sites of the HY zeolite is not affected by deactivation. Finally, the increase of the reaction temperature (to 450 °C) allows limiting the effect of phenol addition on the zeolite activity and stability.
Keywords: Bio-oils; Zeolites; Catalytic cracking; Methylcyclohexane; Phenol; Deactivation; Coking;

Catalytic properties of V2O5/SnO2 towards vapour-phase Beckmann rearrangement of cyclohexanone oxime by Sreejarani K. Pillai; Omanakkutty Gheevarghese; Sankaran Sugunan (130-136).
The catalytic efficiency of the sulfated V2O5/SnO2 systems in the gas-phase Beckmann rearrangement of cyclohexanone oxime is presented in this paper. The catalysts were characterized thoroughly using different techniques like EDX, BET-SA, XRD, FTIR, TGA, 51V NMR. NH3-TPD and hydrocracking of cumene were used for measuring the surface acidity of the prepared catalysts. The results of the investigation suggest that the acidity of the supported vanadia systems plays an imperative role in the activity and selectivity in the reaction.▪V2O5/SnO2 solid acid catalysts have been employed for the vapour-phase Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam. Catalysts with different vanadia loading (3–15 wt%) were prepared by impregnation method and characterized by XRD, BET surface area, FTIR and 51V NMR techniques. The surface acidic properties were determined by temperature programmed desorption and cumene cracking reaction. Under optimized reaction conditions, catalyst with 9 wt% V2O5 gives the maximum amount of desired product (yield 78.8%). However, the catalysts are susceptible for deactivation due to the basic nature of the reaction products (50% deactivation in 5 h). A good correlation was obtained among the rearrangement activities of V2O5/SnO2 catalysts, their weak plus medium acidities (usually of the Brönsted type) and structural properties.
Keywords: V2O5/SnO2 catalysts; Beckmann rearrangement; Acidity;

An FTIR study of the dispersed Ni species on Ni-YSZ catalysts by Carlo Resini; Tzvetomir Venkov; Konstantin Hadjiivanov; Sabrina Presto; Paola Riani; Rinaldo Marazza; Gianguido Ramis; Guido Busca (137-143).
IR spectroscopy of low temperature adsorbed CO and CO + NO has been used to characterize the surface species on a 5% Ni-YSZ catalyst. Dispersed surface Ni species are present on the fresh catalyst, essentially formed by Ni2+, although it is evident that these species are very easily reduced in very mild conditions to zerovalent atomic nickel. Reduction in stronger conditions gives rise to small Ni metal particles, which are however easily reoxidized to bivalent nickel. This work has demonstrated how elastic is the redox state of this catalyst. This is supposed to be a key properties explaining the behaviour of this catalyst in converting ethanol in the presence of water.IR spectroscopy of low temperature adsorbed CO and CO + NO has been used to characterize the surface of 5% Ni-YSZ catalyst. Dispersed surface Ni2+ species are present on the fresh catalyst, which are very easily reduced to zerovalent atomic nickel. Reduction in stronger conditions gives rise to small Ni metal particles, which are very easily reoxidized to bivalent nickel.▪
Keywords: Ni catalysts; Zirconia support; Yttria-stabilized zirconia; IR spectroscopy; CO adsorption; NO adsorption; Ethanol steam reforming; Steam reforming; Reduction; Reducibility;