Surface science has evolved from being a sub-field of chemistry or physics, and has now established itself as an interdisciplinary topic. Knowledge has developed sufficiently that we can now understand catalysis from a surface science perspective. No-where is the underpinning nature of surface science better illustrated than with nanoscience.

Now in its third edition, this successful textbook aims to provide students with an understanding of chemical transformations and the formation of structures at surfaces. The chapters build from simple to more advanced principles with each featuring exercises, which act not only to demonstrate concepts arising in the text but also to form an integral part of the book, with the last eight chapters featuring worked solutions.

TiO 2 is an effective and well-known photocatalyst for water and air purification, but its practical applications in visible light-assisted chemical reactions are hindered mainly by its poor visible light absorption capacity. Nitrogen-doped TiO 2 (N-doped TiO 2) has attracted considerable attention as a photocatalyst, and rapid progress has been made in enhancing the photocatalytic efficiency of TiO 2 under visible light irradiation. N-doped TiO 2 exhibits broad absorption in the visible region, which can allow the utilization of a large part of the solar spectrum. This might be useful for environmental and energy applications, such as the photocatalytic degradation of organic pollutants, solar cells, sensors, and water splitting reactions. This review focuses on the major developments in the synthesis of N-doped TiO 2 and its possible applications in the photocatalytic degradation of organic pollutants and environmental remediation under visible light irradiation.

Highly selective synthesis of diphenylmethane (DPM) was carried out by Friedal–Crafts benzylation of benzene using benzyl chloride (BC) as alkylating agent in the presence of a flow of nitrogen under liquid phase reaction conditions over novel mesoporous SO42−/Al-MCM-41 catalysts with different Si/Al ratios. For these reactions, the influences of various reaction parameters, such as different catalysts, reaction temperature, time, mmol

This paper presents the implementation of the recent methodology called Adaptable Time Warping (ATW) for the automatic identification of mixture of crystallographic phases from powder X-ray diffraction data, inside the framework of a new integrative platform named hITeQ. The methodology is encapsulated into a so-called workflow, and we explore the benefits of such an environment for streamlining discovery in R&D.

Selective partial oxidation of methane to syngas over LaNiO 3 , La 0.8 Ca(or Sr) 0.2 NiO 3 and LaNi 1−x Co x O 3 (where x = 0.2-1) perovskites at extremely short contact time ( ≈0.8 ms) has been investigated. Also, simultaneous oxidative conversion and steam and CO 2 reforming of methane to syngas over LaNiO 3 at short contact time ( ≈9 ms) has been studied at different temperatures and CH 4 /O 2 feed ratios. The catalysts, before and after reaction, were characterized by XRD and SEM. LaNiO 3 perovskite shows high activity and selectivity in the oxidative conversion of methane to syngas. However, the partial substitution of its La by Ca or Sr and also the partial or complete substitution of its Ni by Co causes a large decrease in both its activity and its selectivity. LaNiO 3 is transformed to its catalytically active form, Ni 0 /La 2 O 3 , during the initial period of the process. This catalyst shows very good performance in the simultaneous oxidative conversion (which is exothermic) and steam and CO 2 reforming reactions (which are endothermic) of methane to syngas, at short contact time, operating in a most energy efficient manner and also requiring only a little or no external energy.

It was reported recently that aniline in the presence of ammonia was converted to picolines over zeolite catalysts. The picolines are important intermediates in the dye and resins industries. However, no report has appeared on the reactions of arylamines over zeolites despite the fact that nitrogen heterocycles make up part of the structure of oil shale kerogens. The thermal arrangement of N-alkylaniline hydrochlorides in a sealed tube to give ringalkylated anilines has long been known as the Hoffmann-Martius rearrangement. In this note, the authors describe the rearrangement of N-methylaniline involving a methyl-N bond cleavage to ring-alkylated anilines and N-methylation to N, N-dimethylaniline over H-ZSM-5, H-Theta-1 and H-Y zeolites.

The objective of this work was to demonstrate the viability of the cross ketonization reaction with the triacylglycerol from Cuphea sp. and acetic acid in a fixed-bed plug-flow reactor. The seed oil from Cuphea sp. contains up to 71% decanoic acid and the reaction of this fatty acid residue with acetic acid yields the fragrance compound and insect repellent 2-undecanone. To this end, we screened several ketonization catalysts taken from the literature including CeO 2 , CeO 2 /Al 2 O 3 , CeO 2 /ZrO 2 , MnO x /Al 2 O 3. The catalysts were characterized by N 2 adsorption/desorption, H 2-TPH, CO 2-TPD, and XRD. Each of these catalysts affected the conversion but the highest yield was found with a new coprecipitated mixed metal oxide of empirical formula Fe 0.5 Ce 0.2 Al 0.3 O x. In a flow reactor, Fe 0.5 Ce 0.2 Al 0.3 O x gave 2-undecanone at 91% theoretical yield with reaction conditions of 400 • C, weight hourly space velocity of 2, molar ratio of acetic acid to Cuphea oil of 23, and N 2 carrier gas flow of 125 ml/min at 2.4 bar. This high yield is attributed to the low rate of coke formation on the mixed metal catalyst. In the absence of acetic acid, coupling of the decanoic acid residues gives 10-ketononadecane.

The activation energies for alkene formation via dehydration of alcohols on bridge-bonded oxygen (BBO) vacancy sites of TiO 2 (110) is found to correlate with the inductive electron donating effect of alcohol alkyl groups as measured by the Taft parameter. Based on this correlation we conclude that the reaction involves a single transition state that undergoes concerted rupture of the CO bond of the alkoxide and a C-H bond of the alkyl group attached to the b-carbon. Keywords Alcohols Á Heterogeneous catalysis Á TiO 2 (110) Á Dehydration Á Oxygen vacancies 2 Experimental The experiments were performed in an ultra-high vacuum (UHV) molecular beam scattering chamber (5 • 10-11

The photocatalytic decomposition of aniline has been investigated using Ag + -loaded TiO 2 suspensions as a sensitizer. The amounts of aniline, Ag + and TiO 2 have been optimized by following the rates of decomposition of aniline and formation of product(s). The initial consumption of aniline follows pseudo-first-order kinetics. The loading of 0.2 wt.% of Ag + almost doubled this rate compared to that of the unmodified particles. The increased activity of these particles has been attributed to the modified surface properties of TiO 2 due to the presence of Ag/Ag + on its surface, which may act as a trap for electrons and, thereby, inhibit the e À -h + recombination. Azobenzene has been found to be one of the main products of its oxidation. Its formation has been explained by the direct participation of holes in the oxidation process. Under the used experimental conditions, aniline could be completely decomposed in about 10 h. The addition of Na 2 CO 3 to Ag +loaded TiO 2 suspensions enhances the photodecomposition of aniline significantly. Mechanisms of these processes are discussed. #

Wet catalytic oxidation was performed at room temperature with 1 wt% Fe/MgO, 4 wt% Fe/MgO, 6 wt% Fe/MgO, 15 wt%/MgO and 30 wt% Fe/MgO catalysts. The 6 wt% Fe/MgO catalyst has a maximum capacity of 2.6 g H 2 S/g cat for H 2 S removal. The amounts of paramagnetic Fe 3 cations are correlated with the H 2 S removal capacity of the Fe/MgO catalysts from MoÈ ssbauer experiments. It is observed that the deactivation of the 6 wt% Fe/MgO catalyst can be due to the loss of the paramagnetic Fe 3 cations during the reaction.

The structure of copper iron pyrophosphate catalysts prepared with various atomic ratios of metals and different pretreatment conditions was studied by using XRD, FT-IR, DR UV-vis and H 2 -TPR techniques. The preparation methods modify the phase composition, oxidation state and reducibility of the patterns. The catalytic properties in the selective oxidation of methane to formaldehyde and methanol were examined in both, pulse and flow reactors, using O 2 and/or N 2 O oxidizing agents. The oxidants used impact the onset of methane conversion, the primary oxidation products formation and the methane conversion. The highest single-pass yield of useful oxygenates (1.8%) was achieved with N 2 O over the Cu/Fe ∼ = 1:2 pyrophosphate catalyst which consists mainly of the crystalline Fe II Fe III 2 (P 2 O 7 ) 2 and copper containing nanodomains. Enhanced interaction and cooperation between these phases leading to a synergic effect of Cu and Fe has been emphasized. The Cu II and Fe III species of the above structure can be reduced more easily but at similar temperatures than those in the crystalline CuFe 2 (P 2 O 7 ) 2 . Pulse reaction studies indicate that the lattice oxygen of the catalyst could react with methane molecules producing formaldehyde and methanol and replenishment of the lattice oxygen by N 2 O takes place rather readily and rapidly. The nature of active species, methane conversion and oxygenates selectivity remained almost unchanged during the time on stream.

The Claisen-Schmidt condensation is easily carried out with or without a solvent in the presence of natural phosphate (NP) alone, activated by water, benzyltriethylammonium chloride and both. The role of water and ammonium salt are clearly shown.

We describe an aerosol-liquid cycle that launches the autocatalytic amplification of any initial imbalance of the order of 10 ÿ7 % (1 ppb) up to total chiral purity in a single step process. Crystal nucleation of NaClO 3 is initiated at the aerosol air-water interface where, due to the accumulation of ambient chiral impurities or added hydrophobic chiral aminoacids in tiny concentrations (ppb), the initial levorotatory (l) and dextrorotatory (d) excess will not be produced with equal probability. The enantiomeric yield is then enhanced up to homochirality by recycling the crystallites through a liquid phase. In the absence of added catalysts this process leads to preferential (d) homochiral crystallizations in a ratio of 4:1 which is due to ambient contamination. By adding only 2 ppb of (L) or (D) Phe, we induce a final preferential homochiral crystallization of (d) or (l) handedness, respectively, in a ratio of 2:1.

Ketoprofen is a widespread non-steroidal anti-inflammatory agent used in treatment of acute pain and chronic arthritis. On the other hand, isoquinoline alkaloids are very well known with their wide range of biological activities. From this point of view it is of interest to us to obtain new isoquinolines containing a ketoprofen residue in their structure as new substances with potential biological activity. To estimate general efficacy and safety of the newly obtained compounds, their biological potential has been evaluated.

The reaction of an equimolar mixture of H2 and CO was studied over ZrOr at 350 to 45O"C, 35 atm total pressure, and varying residence times. The isosynthesis reaction mechanisms were studied by monitoring the incorporation of oxygenated compounds into the isosynthesis products. Propionaldehyde and [t3C]acetone, [i3C]isopropanol, and [W]methanol were added to the CO/Hz reactant stream. Their effect on the isosynthesis product distributions and on the isotopic distribution of the products was monitored as a function of oxygenate feed rate. Propionaldehyde, acetone, and methanol were found to incorporate into the isosynthesis products. The isotopic distribution of the products was used to support an isosynthesis reaction scheme that involves CO insertion into a bound aldehyde or ketone as the major chain growth step and a second chain growth step that involves condensation between methoxide and a surface bound enolate. Q 1988 Academic press, IK.

ABSTRACT  Stable, active, and highly selective bifunctional Ni/Al-MCM-41 catalysts were developed for the one-pot synthesis of menthols from citral. The liquid-phase hydrogenation of citral to citronellal was studied on silica-supported noble (Pt, Pd, Ir) and nonnoble (Ni, Co, Cu) metals. It was found that citronellal is selectively formed at the beginning of the reaction only on Pd and Ni catalysts. The consecutive ene-cyclization of citronellal to isopulegols was investigated on solid acids containing exclusively Lewis (ZnO/SiO2) or strong Brönsted (CsHPA) acid sites, and also on catalysts containing both Lewis and Brönsted acid sites of either strong (zeolites, SiO2–Al2O3) or moderate (Al-MCM-41) strength. The isopulegol formation rate was higher on samples exhibiting dual Lewis/Brönsted acidity, such as SiO2–Al2O3, Al-MCM-41, and zeolite HBEA. Based on these previous results, bifunctional catalysts containing Pd or Ni supported on SiO2–Al2O3, Al-MCM-41, or zeolite HBEA were prepared and tested for citral conversion to menthols. The catalyst stability and the effect of hydrogen pressure and metal loading on menthol productivity were also investigated. The best catalyst was Ni(8%)/Al-MCM-41, which yielded more than 90% menthols at 2026.0 kPa and showed no significant deactivation after two consecutive catalytic tests.

A total of 10 noble metal (Rh, Pt, Pd, Ru and Ir) catalysts, either supported on CeO 2 or Ce 0.63 Zr 0.37 O 2 , were prepared. Catalysts were fully characterized using XRD, N 2 adsorption at −196 • C, TEM and H 2 chemisorption. Oxygen storage processes were carefully investigated. The influence of temperature was checked and a key role of oxygen diffusion was further demonstrated. A review of the reactions involved in the CO transient oxidation reaction is finally proposed. (C. Descorme).

The reduction of a 1.3% Rh/TiO 2 sample with carbon monoxide leads to the formation of uniform Rh nanoparticles with a mean diameter of d p E 2.2 nm. Adsorption of CO on the reduced Rh/TiO 2 produces linear and bridged carbonyls bound to metallic Rh 0 sites and only a few geminal dicarbonyls of Rh I . The n(CO) of linear Rh 0 -CO complexes is strongly coverage dependent: it is observed at 2078 cm À1 at full coverage and at ca. 2025 cm À1 at approximated zero coverage. At low coverage, this shift is mainly caused by a dipole-dipole interaction between the adsorbed CO molecules while at high coverage, the chemical shift also becomes important. Hydrogen hardly affects the CO adlayer at high CO coverages. However, on a partially CO-covered surface (y CO E 0.5), the adsorption of H 2 at increasing pressure leads to a gradual shift in the band of linear Rh 0 -CO from 2041 to 2062 cm À1 . Subsequent evacuation almost restores the original spectrum, demonstrating the reversibility of the hydrogen effect. Through the use of 12 CO + 13 CO isotopic mixtures, it is established that the addition of hydrogen to the CO-Rh/TiO 2 system leads to an increase in the dynamic interaction between the adsorbed CO molecules. This evidences an increase in the density of the adsorbed CO molecules and indicates segregation of the CO and hydrogen adlayers. When CO is adsorbed on a hydrogen-precovered surface, the carbonyl band maximum is practically coverage independent and is observed at 2175-2173 cm À1 . These results are explained by a model according to which CO successively occupies different rhodium nanoparticles. † Electronic supplementary information (ESI) available: -S7 and details on the CO interaction with single rhodium surfaces. See

The work describes the results on the hydrogenation of the 2-butyne-1,4-diol (BYD) to 1,4-butanediol (BAD) over both slurry and particulate Raney nickel catalysts (Ra Ni) in batch and in a fixed bed reactor system. The detailed study on the kinetics of the reaction obtained in batch conditions revealed the existence of four stages in the overall hydrogenation network. In the first region, A, the starting BYD produces exclusively cis-2-butene-1,4-diol (cis-BED) and to a lesser degree the respective 4-hydroxybutanal (γ-HALD). In the second region, B, the cis-BED takes part in three parallel reactions of hydrogenation to BAD, isomerization to trans-2-butene-1,4-diol (trans-BED), and the formation of additional γ-HALD. In the third region, C, the trans-BED is mostly engaged in further hydrogenation to BAD, and surprisingly, starts producing the main byproduct, n-butanol (BOL). In the last kinetic region, D, the accumulated 4-hydroxybutanal is slowly hydrogenated to BAD. A completely different reaction profile is observed when the hydrogenation is carried out in an up-flow mode in a fixed bed system. The most important factors controlling the selectivity to BAD are the temperature, the contact time, and the pH of the liquid feed. It is also found that both the surface area of the catalyst and the presence of properly selected promoters, introduced into the Ra Ni system, can lead to a drastic reduction in the level of BOL and can virtually eliminate the formation of the second byproduct, 2-(4-hydroxybutoxy) tetrahydrofuran (HBOTHF).

NiS-P zeolite was prepared by ion exchange and precipitation procedures and it was characterized by FT-IR, SEM and thermal methods. The prepared composite was used as a catalyst in the photodecolorization process of Eriochrome Black T (E.B.T.) dye in aqueous solution under UV irradiation. The effect of key operating parameters such as catalyst dosage, temperature, initial concentration of the dye and initial pH of the solutions were studied on the decolorization process of dye. The primary objective was to determine the optimal conditions for each of the parameters. UV-vis spectrophotometric measurements were performed for the determination of decolorization and mineralization extents. The optimal operation parameters were found as follows: pH 9.1, 0.8 g L −1 of catalyst loading and 40 ppm of dye concentration. The NiS particles out of zeolite framework did not show significant decolorization efficiency. The decolorization process obeyed first-order kinetics.

The potential of mesoporous silica-alumina (MSA) modified by acid leaching as alternative support for Pt catalysts was studied in hydrodesulfurization (HDS) of thiophene and benzothiophene. The supports were characterized by N 2 adsorption, XRD, 27 AL MAS NMR, electron microscopy (SEM, HRTEM) and by activities in cyclohexene isomerization and cumene cracking. The composition of the catalysts and Pt dispersion were determined by ICP and H 2 or CO sorption, respectively. Progressive leaching of the parent MSA from 50% Al 2 O 3 to 11% Al 2 O 3 content led to increase of the BET surface area and exposition of strong acidity. This positively affected the activities of the reduced Pt catalysts in thiophene HDS. Deposition of 1.5 wt.% Pt on MSA (11% Al 2 O 3) by using Pt(NH 3) 4 (OH) 2 as precursor gave the best catalyst, several times more active in thiophene HDS than the weight equivalents of sulfided CoMo/Al 2 O 3 or reduced Pt/HY zeolite. In benzothiophene reaction, its activity was slightly above that of CoMo/Al 2 O 3 and about twofold compared to Pt/HY.

This work demonstrates the high potential of a new class of catalytic materials based on nickel for the oxidative dehydrogenation of ethane to ethylene. The developed bulk Ni-Nb-O mixed oxides exhibit high activity in ethane ODH and very high selectivity (∼90% ethene selectivity) at low reaction temperature, resulting in an overall ethene yield of 46% at 400 • C. Varying the Nb/Ni atomic ratio led to an optimum catalytic performance for catalysts with Nb/Ni ratio in the range 0.11-0.18. Detailed characterization of the materials with several techniques (XRD, SEM, TPR, TPD-NH 3 , TPD-O 2 , Raman, XPS, electrical conductivity) showed that the key component for the excellent catalytic behavior is the Ni-Nb solid solution formed upon the introduction of niobium in NiO, evidenced by the contraction of the NiO lattice constant, since even small amounts of Nb effectively converted NiO from a total oxidation catalyst (80% selectivity to CO 2 ) to a very efficient ethane ODH material. An upper maximum dissolution of Nb 5+ cations in the NiO lattice was attained for Nb/Ni ratios 0.18, with higher Nb contents leading to inhomogeneity and segregation of the NiO and Nb 2 O 5 phases. A correlation between the specific surface activity of the catalysts and the surface exposed nickel content led to the conclusion that nickel sites constitute the active centers for the alkane activation, with niobium affecting mainly the selectivity to the olefin. The incorporation of Nb in the NiO lattice by either substitution of nickel atoms and/or filling of the cationic vacancies in the defective nonstoichiometric NiO surface led to a reduction of the materials nonstoichiometry, as indicated by TPD-O 2 and electrical conductivity measurements, and, consequently, of the electrophilic oxygen species (O − ), which are abundant on NiO and are responsible for the total oxidation of ethane to carbon dioxide.

Sulfate–zirconia catalysts were prepared via the colloidal-sol–gel method using ZrOCl2as precursor. After precipitation and washing, the solids were peptized with a 1 : 1 mixture of CH3COOH and H2SO4. The promoters were introduced as gallium, indium, or thallium nitrates into the solution containing the zirconium sols. After a gel formation period, the samples were dried and calcined. The catalysts were

The synthesis of mesoporous transition-metal oxides has been extensively studied because of their wide range of potential applications. [1] Examples of such compounds include mesoporous TiO 2 , [2, ZrO 2 , [2, 4] Nb 2 O 5 , [2, 3b, 5] Ta 2 O 5 , [2, (Nb,Ta) 2 O 5 , [2, SnO 2 , [2, 8] and WO 3 , [2] which are used as a variety of heterogeneous catalysts, such as solid-acid catalysts, [4b,e,f,h, 5d, 6f,g] photocatalysts, [3b,f-h, 6b,h] oxidation catalysts, [5c] and catalyst supports. [4d,g] Solid-acid catalysts, which are reusable and readily separable from reaction products, have been widely investigated as direct replacements for liquid acids to reduce the impact on the environment and to decrease costs. The use of mesoporous transition-metal oxides is an interesting approach to developing a solid-acid catalyst with enhanced activity. The mesopores in the oxide allows the reactants access additional active acid sites in the pores, resulting in improved rates of acid catalysis. Sulfated mesoporous niobium and tantalum oxides have been reported to exhibit remarkable activity in acid-catalyzed Friedel-Crafts alkylation and isomerization. [5d, 6f,g] However, the use of the recycled catalyst remains difficult, a result of the leaching of sulfate species, as reported for mesoporous silica and organosilicas bearing sulfonic acid groups. Herein, mesoporous Nb-W mixed oxides are examined as solid-acid catalysts, these give very high catalytic performance in Friedel-Crafts alkylation, hydrolysis, and esterification, which originates from the mesoporous structure and different acid properties formed by specific Nb and W concentrations.

Carbon nanotubes (CNTs) are currently attractive material for a diverse range of applications because of their extraordinary mechanical and electrical properties. The present study is aimed to synthesize carbon nanotubes by Catalytic chemical vapor deposition (CCVD) and effect of catalyst loading on the carbon deposition. CCVD is one of the best methods to produce carbon nanotubes (CNTs) in large scale and high quality. In this paper, we synthesized the carbon nanotubes by combination of acetylene and LPG as carbon sources and Fe–Co/Al2O3 as a catalyst. The synthesis was carried out at 700 °C in quartz reactor for 30 min. The obtained CNTs were characterized by scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and X-ray Diffraction (XRD).

Au/Mg(OH)2 catalyst was modified with different amounts of ascorbic acid. After dehydration at 350°C, in various atmospheres, the modified Au/MgO catalysts were characterized and tested in the oxidation of CO. It has been shown for the first time that at high CO pressure supported gold chemisorbs CO and the apparent gold dispersion can be determined. The oxidation of CO was

The hydrogenation of maleic acid was investigated using a bimetallic Ru–Re/C catalyst powder in a semi-batch stirred slurry reactor with the main objective of developing a kinetic model that would provide reliable predictions of the observed reactant and product ...

The present work summarizes the recent activities of our laboratory in the field of solar-aided hydrogen production with structured monolithic solar reactors. This reactor concept, ''transferred'' from the well-known automobile exhaust catalytic after-treatment systems, employs ceramic supports optimized to absorb effectively solar radiation and develop sufficiently high temperatures, that are coated with active materials capable to perform/catalyze a variety of ''solar-aided'' reactions for the production of hydrogen such as water splitting or natural gas reforming. Our work evolves in an integrated approach starting from the synthesis of active powders tailored to particular hydrogen production reactions, their deposition upon porous absorbers, testing of relevant properties of merit such as thermomechanical stability and hydrogen yield and finally to the design, operation simulation and performance optimization of structured monolithic solar hydrogen production reactors. This approach, among other things, has culminated to the world's first closed, solar-thermochemical cycle in operation that is capable of continuous hydrogen production employing entirely renewable and abundant energy sources and raw materials -solar energy and water, respectively -without any CO 2 emissions and holds, thus, a significant potential for large-scale, emissions-free hydrogen production, particularly for regions of the world that lack indigenous resources but are endowed with ample solar energy. #

The effect of temperature in the 293-473 K range, on the secondary electron emission (SEE) yield of single crystal and polycrystalline diamond film surfaces is reported. For the polycrystalline films the SEE yield was found to decay as function of electron irradiation dose while for the single crystal an increase occurs first, followed by a decrease. For both surfaces, the

Photocatalytic reduction of mercury in aqueous solutions using PW 12 O 40 3or SiW 12 O 40 4as photocatalysts has been studied as a function of irradiation time, concentration of Hg(II), polyoxometalate, and organic substrate in the presence or absence of dioxygen. The photocatalytic cycle starts with irradiation of polyoxometalate, goes through the oxidation of, for instance, propan-2-ol (used as sacrificial reagent), and closes with the reoxidation of reduced polyoxometalate by Hg 2+ ions. Mercury(II) is reduced to mercury(I) and finally to Hg 0 giving a dark-gray deposit, following a staged one-by-one electron process and a firstorder kinetics in [Hg 2+ ]. The process is slightly more efficient in the absence of dioxygen, while the increase of either catalyst or propan-2-ol concentration results in the augmentation of the rate of reduction till a certain point where it reaches a plateau. The results show that this method is suitable for a great range of mercury concentration from 20 to 800 ppm achieving almost complete recovery of mercury up to nondetected traces (<50 ppb). In addition, this homogeneous process demonstrates advantages such as the lack of necessity for separation of the zero state metal from the catalyst and ensures that the precipitation of metal will not poison the catalyst or hinder its photocatalytic activity.

Quinoxaline derivatives have been synthesized in high yields in the presence of cellulose sulfuric acid as an inexpensive, recyclable and biodegradable solid acid catalyst in H 2 O or EtOH at room temperature. To cite this article: A. Shaabani et al., C. R. Chimie 12 (2009). #

Carbon-carbon coupling reactions are of enormous importance in organic synthesis. Heck and other palladium-mediated reactions were among the first to fulfill the criteria of high selectivity, tolerance of functional groups, and high catalyst efficiency. The development of well-defined initiators for metathesis-based reactions was initially stimulated by reactions related to polymer chemistry. However, with these initiators in hand, olefin metathesis has become a powerful tool, maybe the tool in organic synthesis. With a few exceptions, reactions that require high ee are still the domain of molybdenum-based Schrock initiators. Nevertheless, "simple" metathesis-based reactions such as ring-opening cross-metathesis, enyne metathesis, and others are nowadays preferably accomplished by using air-and moisture-tolerant ruthenium-based catalysts based on N-heterocyclic carbenes (NHCs), usually referred to as Grubbs and Grubbs-Hoveyda catalysts. Both NHC ligands and carbene groups in ruthenium-derived catalysts have been optimized over the years. So far, most variations in NHC were accomplished by using different substituents on the NHC and by switching from imidazol-2-ylidene to imidazolin-2-ylidene. Even small, sometimes incremental, variations resulted in dramatic changes in reactivity. Recently, we reported new systems for olefin metathesis generated by replacing one or two chloro ligands in Grubbs-Hoveyda-type catalysts by strongly electron-withdrawing groups such as trifluoroacetate and trifluoromethanesulfonate, and their special features in organic synthesis and polymer chemistry. Our latest goal was to investigate the reactivity of a new class of ruthenium-based metathesis catalysts prepared from tetrahydropyrimidin-2-ylidenes. This was accomplished by synthesizing [RuCl 2 (NHC){=CH-2-(2-PrO)-5-NO 2 -C 6 H 3 }] (1; NHC = 1,3bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) and its bis(trifluoroacetate) analogue [Ru(CF 3 -COO) 2 (NHC)(=CH-2-(2-PrO)-5-NO 2 -C 6 H 3 ) (2). In view of the strong demand for supported catalysts, heterogeni- [a] Dr. Innsbruck (Austria) With 0.24-2 % of the supported catalysts, yields in RCM and ROCM were in the range of 76-100 %. Leaching of ruthenium was low and resulted in Ru contaminations of the products of less than 0.000014 % (0.14 ppm).

Product stereochemistry, double-bond isomerization, deuterium incorporation, and hydrogen uptake data were obtained for the hydrogenation/deuteration of a number of cyclic olefins over the various supported noble-metal catalysts. The data from the Pt-catalyzed reactions are in substantial agreement with previously reported results that have been explained by the Horiuti-Polanyi mechanism. It was also found that while rhodium was similar to platinum in its reaction characteristics, it is more susceptible to steric factors and there is more equilibration of the half-hydrogenated state than is observed with platinum. Olefin hydrogenations over palladium are quite different, taking place by way of a ?r-allyl-absorbed species rather than the 1,2-q entity utilized in the Horiuti-Polanyi process. Limited data indicate that while the use of ruthenium gives anomolous results, iridium appears to be mechanistically similar to platinum.

BaTiO 3 oxides were prepared by the solid-phase crystallization (spc) method and tested for the partial oxidation of CH 4 to synthesis gas. The impregnation (imp) method was used for comparison. spc-Ni/SrTiO 3 showed the highest activity as well as the highest sustainability against both coke formation and reoxidation of Ni metal, followed by spc-Ni/BaTiO 3 , spc-Ni/CaTiO 3 , and then imp-Ni/SrTiO 3. The order of the activity was clearly confirmed in the reaction at high space velocity. Both transmission electron microscopy and temperature-programmed reduction showed the presence of finely dispersed and stable Ni metal particles on the catalysts and their amount correlated well with the order of the catalytic activity. It is suggested that incorporation of Ni is enhanced in SrTiO 3 , followed by BaTiO 3 , and much less in CaTiO 3 , resulting in the higher dispersion of Ni metal particles on SrTiO 3. Less heat was generated over spc-Ni/SrTiO 3 during CH 4 oxidation, suggesting that the heating of the catalyst bed by CH 4 combustion must be quickly compensated for by endothermic reforming reactions. Oxygen mobility was highest over spc-Ni/SrTiO 3 as judged from CO 2 pulse measurements. The high sustainability against coke formation may be due to the high activity of finely dispersed nickel metal particles for the reforming reactions partly assisted by the mobile oxygen on the catalyst.

The conditions for preparation of high surface area zirconia were studied. Samples were prepared by precipitation from aqueous solutions of zirconium chloride with ammonium hydroxide. The order of addition of the reactants was found to affect the surface area. Digestion of the hydrous zirconia is the key to high surface area zirconia without the necessity of adding other oxides or dopants. Both the temperature and the time of digestion are important parameters. Zirconia with surface area in excess of 220 m2/g after calcination at 500°C have been obtained. The materials maintained a surface area of >90 m2/g even after heat treatment at 900°C for 12 h. In addition, digestion led to the formation of the tetragonal allotrope of zirconia. Samples which had been digested for long times at 100°C are tetragonal and maintain this phase up to 1000°C. The effects of digestion seems to be related to a phase transformation of the hydrous precursor at around 80°C. A mechanism based on defect density is postulated to explain the phase stability.

Vanadium phosphate (VPO) is well known as a heterogeneous catalyst in gas phase oxidation reactions. Till date, this material has not drawn much attention for its application in liquid phase reactions. This paper briefly highlights our recent research on vanadyl metaphosphate concerning its fabrication, characterization and application towards liquid phase oxidation of benzyl alcohol to benzaldehyde using tert-butyl hydroperoxide (TBHP) as the oxidant. In our preliminary catalytic studies, we find that the VO(PO 3 ) 2 exhibits extraordinarily high activity and selectivity in oxidation of benzyl alcohol under mild conditions. The benzyl alcohol conversion is largely increased but the selectivity for benzaldehyde is slightly decreased with the increase in reaction period or temperature. The present catalyst VO(PO 3 ) 2 showed remarkable catalytic activity with respect to other catalytic system; conversion and selectivity with respect to aldehyde is 97 and 99%, respectively.

The polyoxometalate H 5 PV 2 Mo 10 O 40 (1) is deposited on cotton cloth, polyacrylic fiber, nylon fiber, carbon powder (Ambersorb 572), and the Japanese "self-deodorizing" fabric Smoklin by immersion of these materials in aqueous solutions of 1 followed by evaporation of the water. DRIFT spectra and chemical reactivity indicate that 1 is not damaged during deposition on the materials. More significantly, they catalyze O 2-based oxidations of two representative and common toxics in air, acetaldehyde and 1-propanethiol, in addition to a representative thioether, tetrahydrothiophene. These aerobic oxidations proceed heterogeneously with the substrates in the liquid phase and under unusually mild conditions (mostly ambient temperature and pressure). One representative reaction, CH 3 CHO + O 2 → CH 3 COOH, catalyzed by several 1-fabric materials is examined in some detail. Kinetics, radical scavenging, and other experiments are consistent with the 1-fabric functioning primarily as a radical chain initiator. Surface area measurements and scanning electron microscopy of two representative materials, 1polyacrylic and 1-Smoklin, before and after deposition of 1 and after catalysis indicate that the fibers are not demonstrably altered by deposition of 1, and that the 1-fabric catalysts are not significantly deactivated by use. In all cases, the surface areas are <0.5 m 2 /g by BET N 2 adsorption, and the deposition morphology is clumps of 1 microcrystals covering <5% of the fiber/cloth surface. Smoklin, designed and specified to be effective at removing the toxic and/or odorous molecules at ambient temperature, does not exhibit significant activity for catalytic O 2 oxidations in our evaluations. In contrast, 1-Smoklin is quite active for all these processes.

Carbon nanotubes supported iron catalysts were prepared by incipient wetness, deposition/precipitation using K 2 CO 3 , and deposition/precipitation using urea. The incipient wetness method and the deposition/precipitation technique using urea yielded highly dispersed Fe 3+ on the carbon nanotubes support. The deposition/precipitation technique using K 2 CO 3 also yielded larger Fe 2 O 3 -crystallites. After reduction the three catalysts had similar metal surface areas. Nevertheless, the activity of these catalysts in the Fischer-Tropsch synthesis differed significantly with the catalyst prepared by incipient wetness being the most active one. It is speculated that the differences in the performance of the catalysts might be attributed to the different crystallite size distributions, which would result in a variation in the amount of the different phases present in the catalyst under reaction conditions. The selectivity in the Fischer-Tropsch synthesis over the three catalysts seems to be independent of the method of preparation.

The decomposition of 5-benzhydryl-1H-tetrazole in an N-methyl-2-pyrrolidone/acetic acid/water mixture was investigated under a variety of high-temperature reaction conditions. Employing a sealed Pyrex glass vial and batch microwave conditions at 240 °C, the tetrazole is comparatively stable and complete decomposition to diphenylmethane requires more than 8 h. Similar kinetic data were obtained in conductively heated flow devices with either stainless steel or Hastelloy coils in the same temperature region. In contrast, in a flow instrument that utilizes direct electric resistance heating of the reactor coil, tetrazole decomposition was dramatically accelerated with rate constants increased by two orders of magnitude. When 5-benzhydryl-1H-tetrazole was exposed to 220 °C in this type of flow reactor, decomposition to diphenylmethane was complete within 10 min. The mechanism and kinetic parameters of tetrazole decomposition under a variety of reaction conditions were investigated. A number of possible explanations for these highly unusual rate accelerations are presented. In addition, general aspects of reactor degradation, corrosion and contamination effects of importance to continuous flow chemistry are discussed.

Some new 1,4-distyrylbenzene derivatives were synthesized by using immobilized palladium nanoparticles on silica-bonded N-propyl morpholine (PNP-SBNPM) as a heterogeneous catalyst. These one-pot reactions afforded a range of stereoselective, symmetrical (E)-1,4-distyrylbenzene derivatives with high yields (78-90%). The green catalyst system is recyclable and allows facile product isolation. The recycled catalyst could be reused six times without appreciable loss of catalytic activity.

The study of the behavior of palladium, and noble metals in general, in respect of fundamental gas-metal interactions and reactive chemistry, has attracted a great deal of attention over a great many years. The intrinsic importance of a range of commercial applications of palladium-not least of which being automotive exhaust catalysis-coupled to a fundamental desire to understand the basic physics and chemistry of such interactions, are the prime drivers for this interest. In the exhaust catalysis application, the catalyst has to operate in conditions wherein the redox potential of the feedstock can change in a highly dynamic manner. Further, the interplay between oxidized and reduced phases of palladium is of central importance to palladium activity in methane oxidation catalysis. As such, a comprehension of the dynamic redox behavior of Pd and other noble metals is of considerable importance.

Abstract
Copper-catalyzed cross-coupling reactions offer a powerful tool for the formation of carbonheteroatom
bonds. Copper catalysis has an indisputable advantage over the other catalytic
systems due to its low cost and the use of readily accessible and stable ligands. Among the
various copper-catalyzed coupling reactions, C-S bond forming reactions have gained much
attention due to its applications in the synthesis of molecules having biological and
pharmaceutical impact. This review illustrates the current strategies and applications of Cu-catalyzed
C-S cross coupling reactions.