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Abstract: The water–gas shift (WGS) reaction on co-precipitated NiO–ZnO catalysts at different reduction temperatures has been studied by a temperature-programmed reaction using in situ diffuse reflectance infrared Fourier Transform Spectroscopy, coupled with mass spectroscopic (in situ DRIFTS/MS) techniques. The results reveal that a catalyst reduced at 493 K (labeled H220) showed higher activity than one reduced at 673 K (labeled H400) due to the ability of NiO on the H220 catalyst to promote CO conversion of the WGS reaction. In situ DRIFTS/MS studies show that there are three adsorbed species over the H220 catalyst at room temperature: adsorbed CO bands, molecularly adsorbed H2O and carboxyl species. Increasing the temperature to 423 K led to the emergence of CO2 and H2 and the disappearance of carboxyl species. However, the low catalytic activity of the H400 catalyst could be attributed to the conversion of the NiO sites to reduced Ni metal sites, which (i) adsorbed CO as the strong linearly bonded CO on the catalyst surface, slowing down the CO reaction, and (ii) showed a lower H2O uptake. [Copyright &y& Elsevier]

Abstract: Comparative studies of the oxygen reduction kinetics and mechanisms of CoFeN x /C catalysts have been conducted with rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) in aqueous acid and alkaline solutions, as well as acidic and alkaline polymer electrolytes. The CoFeN x /C catalysts in this study were obtained by the pyrolysis of hemin and a cobalt porphyrin. In an alkaline electrolyte, a larger electron transfer coefficient (0.63) was obtained in comparison to that in an acidic electrolyte (0.44), signifying a lower free energy barrier for oxygen reduction. The kinetic rate constant (2.69 × 10−2 cm s−1) for catalytic oxygen reduction in alkaline solution at 0.6 V (versus RHE) is almost 4 times larger than that in acidic solution (7.3 × 10−3 cm s−1). A synergetic catalytic mechanism is proposed. The overall reduction is a 4-electron reduction of oxygen. The obtained CoFeN x /C catalyst was further evaluated as a cathode catalyst in single fuel cells with acidic, neutral and alkaline electrolyte membranes. The order of the single cell performances either for power density or for stability is acidic > neutral > alkaline. The different behaviors of the CoFeN x /C catalyst in half cell and single cell are discussed. [Copyright &y& Elsevier]

Highlights: [•] DeNOx-reaction had a strongly negative impact on the oxidation of elemental mercury. [•] DeNOx-reaction induced reduction of already oxidised mercury. [•] The same reduction occurred when oxidising volatile organic hydrocarbons. [•] Hypothesis will be assumed that the reduction is caused by reduced vanadium species. [ABSTRACT FROM AUTHOR]

Highlights: [•] CeO2-MoO3/TiO2 catalyst is much more active than CeO2/TiO2 for the NH3-SCR. [•] The existed MoO3 can prevent the formation of inactive nitrate species. [•] More Brønsted acid sites formed on the catalyst surface due to the presence of Mo. [•] The activated NH x species react with NO or adsorbed NO2. [ABSTRACT FROM AUTHOR]

Regel missachtet: Die Stereochemie einer Hydroborierung wird gewöhnlich durch suprafacialen Angriff von Wasserstoff und Bor an der gleichen π ‐ Seite eines Substrats bestimmt. Diese grundlegende Regel der cis ‐ Addition kann jetzt für interne Alkine mit [Cp*Ru(MeCN)3]PF6 (Cp*=η5 ‐ C5Me5) als Katalysator gebrochen werden. Die daraus resultierende trans ‐ selektive Hydroborierung ermöglicht die Synthese von E ‐ konfigurierten Alkenylbor ‐ Derivaten. [ABSTRACT FROM AUTHOR]

Highlights: [•] Clay/polypyrrole/silver hybrids via simple photopolymerization process using AgNO3 sensitizer. [•] Silanization of the clay imparts polypyrrole/silver-rich surface. [•] The ternary silanized clay/polypyrrole/silver hybrids are exfoliated. [•] The hybrid structures are effective catalysts for the reduction of methylene blue. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a transparent NiCo2S4 thin film as an effective counter electrode (CE) was incorporated into a Pt-free dye-sensitized solar cell (DSC) for the first time. NiCo2S4 was synthesized via a facile solvothermal method and then subjected to electrophoresis onto a fluorinated tin oxide (FTO) glass substrate. X-ray diffraction, energy dispersive spectrum, and field-emission scanning electron microscope confirmed that the NiCo2S4 nanoparticles were successfully synthesized and deposited onto the FTO substrate, while the electrochemical analyses showed its superior electrocatalytic activity for the I3 − reduction compared to the conventional Pt CE. Additionally, the NiCo2S4 CE demonstrated a high transmittance (>75%) at visible wavelengths. Thus, the DSC assembled with the transparent NiCo2S4 CE achieved a promising photovoltaic conversion efficiency of 6.14% in comparison with that using the Pt CE (6.29%). [Copyright &y& Elsevier]

Abstract: Monodispersed sodium alginate (SA) stabilized silver nano bar and hydroxyl propyl methyl cellulose (HPMC) stabilized silver nano bar have been synthesized by photochemical method. The nanoparticles are characterized by UV–VIS–NIR spectroscopy, transmission electron microscopy (TEM) and selected area electron diffraction (SAED) study. Catalytic reduction of 4-nitrophenol (4-NP) by sodium borohydride in presence of nanoparticles is also evaluated. The kinetic data obtained by monitoring the change in UV–Vis absorption spectra of 4-NP are explained by Langmuir–Hinshelwood model. It is observed that the rate of reduction is higher in SA stabilized Ag nano bar than the HPMC stabilized Ag nano bar. [Copyright &y& Elsevier]

This study provides insight into the mechanistic and performance features of the cyclic reduction of NO by CO in the presence and absence of excess water on a Pt-Rh/Ba/AlO NO storage and reduction catalyst. At low temperatures (150-200 °C), CO is ineffective in reducing NO due to self-inhibition while at temperatures exceeding 200 °C, CO effectively reduces NO to main product N (selectivity >70 %) and byproduct NO. The addition of HO at these temperatures has a significant promoting effect on NO conversion while leading to a slight drop in the CO conversion, indicating a more efficient and selective lean reduction process. The appearance of NH as a product is attributed either to isocyanate (NCO) hydrolysis and/or reduction of NO by H formed by the water gas shift chemistry. After the switch from the rich to lean phase, second maxima are observed in the NO and CO concentrations versus time, in addition to the maxima observed during the rich phase. These and other product evolution trends provide evidence for the involvement of NCOs as important intermediates, formed during the CO reduction of NO on the precious metal components, followed by their spillover to the storage component. The reversible storage of the NCOs on the AlO and BaO and their reactivity appears to be an important pathway during cyclic operation on Pt-Rh/Ba/AlO catalyst. In the absence of water the NCOs are not completely reacted away during the rich phase, which leads to their reaction with NO and O upon switching to the subsequent lean phase, as evidenced by the evolution of N, NO and CO. In contrast, negligible product evolution is observed during the lean phase in the presence of water. This is consistent with a rapid hydrolysis of NCOs to NH, which results in a deeper regeneration of the catalyst due in part to the reaction of the NH with stored NO. The data reveal more efficient utilization of CO for reducing NO in the presence of water which further underscores the NCO mechanism. Phenomenological pathways based on the data are proposed that describes the cyclic reduction of NO by CO under dry and wet conditions. [ABSTRACT FROM AUTHOR]

Fe-MCM-41, one kind of high-ordered mesoporous materials catalysts, with molar ratio of Fe/Si = 0.01-0.1, was synthesized by hydrothermal method from coal-series kaolin. Fe-MCM-41 catalysts were characterized by Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, N 2 adsorption-desorption, x-ray photoelectron spectroscopy, and UV-vis spectroscopy. The results clearly indicated that: (1) all the samples exhibited typical hexagonal arrangement of mesoporous structure; (2) the incorporation of tiny amount of Fe 3+ onto the surface and pore channel of MCM-41 mesoporous materials could efficiently promote the deNO x activity of these catalysts. Moreover, the Fe-MCM-41 mesoporous materials were evaluated in the selective catalytic reduction of NO with NH 3. The results showed that Fe-MCM-41 catalyst with Fe/Si = 0.05 showed the highest catalytic activity at 350 °C, a gas hourly space velocity of 5000 h −1, n(NH 3)/ n(NO) = 1.1, and O 2% = 2.5%. [ABSTRACT FROM AUTHOR]

Photochemical catalytic CO2 reduction to formate and methanol has been demonstrated in an aqueous homogeneous system at pH 5.0 comprising ruthenium(II) trisphenanthroline as the chromophore, pyridine as the CO2 reduction catalyst, KCl, and ascorbic acid as a sacrificial reductant, using visible light irradiation at 470 ± 20 nm. Isotopic labeling with 13CO2 yields the six-electron-reduced product 13CH3OH. After 1 h photolysis, the two-electron-reduced product formate and the six-electron-reduced product methanol are produced with quantum yields of 0.025 and 1.1 × 10–4, respectively. This represents 76 and 0.15 turnovers per Ru for formate and methanol, respectively, and 152 and 0.9 turnovers per Ru on an electron basis for formate and methanol, respectively. The system is inactive after 6 h irradiation, which appears largely to be due to chromophore degradation. A partial optimization of the methanol yield showed that high pyridine to Ru ratios are needed (100:1) and that the optimum pH is near 5.0. The presence of potassium salts enhances the yield in formate and methanol by 8- and 2-fold, respectively, compared to electrolyte-free solutions; however, other alkali and alkali earth cations have little effect. The addition of small amounts of solid metal catalysts immobilized on carbon had either no effect (M = Pt or Pd) or deleterious effects (M = Ni or Au) on methanol production. Addition of colloidal Pt resulted in no methanol production at all. This is in notable contrast with the pyridine-based electrocatalysis of CO2 to methanol in which metallic or conductive surfaces such as Pt, Pd, or p-type GaP are necessary for methanol formation. [ABSTRACT FROM AUTHOR]

The poor discharge and recharge efficiency demonstrated by lithium-air batteries renders the search for highly active and inexpensive oxygen reduction and evolution catalysts crucial to the development of these energy-storage and conversion devices. Previous works have shown that manganese oxides are promising lithium-oxygen cathode catalysts, which is in agreement with their remarkable activities for the reduction and evolution of oxygen in aqueous media. Motivated by these resembling catalytic behaviors, we prepared and characterized a number of manganese oxide modifications directly on carbon black and attempted to correlate their oxygen reduction and evolution activities in aprotic and aqueous electrolytes. Although our results cannot confirm this correlation, they provide valuable insight into the reaction mechanisms at play in each medium. More precisely, in 0.1 M potassium hydroxide, the reduction of oxygen is related to the reduction of a manganese(III) intermediate whereas the oxidation of hydrogen peroxide (which was regarded as a mimic of the lithium peroxide produced upon lithium-oxygen battery discharge) correlates with the transition between manganese(II) and manganese(III) phases. In the aprotic medium, manganese oxide cathodes prefilled with lithium peroxide showed a strong catalytic effect but were not active in the oxidation of lithium peroxide produced in the previous discharge. This discrepancy is thought to arise from the stark differences in the sizes and morphologies of the lithium peroxide involved in each test, which implies that the catalytic activity of a material for the oxidation of lithium peroxide prefilled on electrodes is not indicative of its behavior in the charging of a real lithium-oxygen cell. [ABSTRACT FROM AUTHOR]

Abstract: A variety of association complexes of synthetic flavin with diaminopyridine and melamine receptors are described in terms of synthesis, association properties, and catalytic activities for aerobic hydrogenation of olefins. The 1:1 association complex of lumiflavin 1 with 2,6-bis(acylamino)pyridine receptor bearing 3,4,5-trialkoxybenzyl ether dendron unit 2 acts as an efficient supramolecular organocatalyst for the aerobic reduction of styrene at ambient temperature under atmospheric air pressure. [Copyright &y& Elsevier]

Abstract: Alkaline (earth-) carbonates are applied in NO x storage and reduction catalysts, given their ability to accumulate NO2 in excess oxygen environments, and releasing it under rich-burn conditions. The dependency of their conductivity on the NO x loading state makes them suitable as NO2 sensitive layers and enables the in situ characterization of the status of such catalyst systems. The conductivity of the NO x trap components BaCO3 and K2CO3, with different morphologies, is analyzed in various NO x containing atmospheres by impedance spectroscopy. While the stepwise uptake of NO2 can be detected electrically on both carbonates, only a weak corresponding influence of NO is detected. The increase in the conductivity of the carbonates during NO2 accumulation can be described as a diffusion controlled process with a characteristic nucleation delay in the case of BaCO3. Arrhenius-like plots comparing the conductivities of the carbonates in the unloaded and NO2 saturated states from 250 to 600°C reveal that the conductivity of BaCO3 is more sensitive to NO2 than those of K2CO3/La-Al2O3, but the latter exhibiting about five orders of magnitude higher conductivity. [Copyright &y& Elsevier]

The diminished surface-area-normalized catalytic activity of highly dispersed Pt nanoparticles compared with bulk Pt is particularly intricate, and not yet understood. Here we report on the oxygen reduction reaction (ORR) activity of well-defined, size-selected Pt nanoclusters; a unique approach that allows precise control of both the cluster size and coverage, independently. Our investigations reveal that size-selected Pt nanoclusters can reach extraordinarily high ORR activities, especially in terms of mass-normalized activity, if deposited at high coverage on a glassy carbon substrate. It is observed that the Pt cluster coverage, and hence the interparticle distance, decisively influence the observed catalytic activity and that closely packed assemblies of Pt clusters approach the surface activity of bulk Pt. Our results open up new strategies for the design of catalyst materials that circumvent the detrimental dispersion effect, and may eventually allow the full electrocatalytic potential of Pt nanoclusters to be realized. [ABSTRACT FROM AUTHOR]

Highlights: [•] A multifunctional catalyst/storage material is prepared to maximize NO removal. [•] The role of the different active sites in the lean/rich cycles is established. [•] The cobalt catalytic function oxidizes the NO to NO2. [•] The basic properties of the Co/Mg/Al mixed oxide are enhanced by doping with Na. [•] The introduction of V enables the reduction of the nitrate decomposition products. [ABSTRACT FROM AUTHOR]

Highlights: [•] K2O/Al2O3 and Pt–K2O/Al2O3 with varying K loadings were prepared. [•] K2O(20)/Al2O3 formed more thermally stable nitrate species than K2O(10)/Al2O3 upon NO2 adsorption. [•] Temperature of max. NO x uptake shifted from 573K to 723K with increasing K loadings from 10wt% to 20wt%. [•] Moreover, the efficiency of K for storing NO x increased more than three times. [ABSTRACT FROM AUTHOR]

Nanostructured C-based catalysts have been developedto be usedin continuously operated (open-flow) reactors for the removal of bromatesand nitrates from polluted water. The catalysts contain transition-metal(Pd, Cu, and Sn) nanoparticles (NPs) supported on activated carbonfiber fabrics, honeycomb monoliths, and sintered metal fiber (SMF)filters coated by carbon nanofibers (CNF). All catalysts were effectivein the reduction of nitrates and bromates present in polluted naturaland industrial waters. The best results for nitrate removal in termsof selectivity to N2were obtained with the NPs of Pd–Sn(2:1) supported on a mesoporous 5% CNF/SMF. In bromate removal, thesame 5% CNF/SMF support with monometallic Pd0NPs showedthe highest performance because of suppressed mass-transport limitations.Finally, the (0.3% Pd + 0.15% Sn)/5% CNF/SMF catalyst was tested insimultaneous bromate and nitrate removal from synthetic polluted watersand shown to be suitable for attaining pollutant concentrations belowthe legislation limits (50 mg/L for nitrates and 10 μg/L forbromates since 2009 in Europe). The continuously operated reactordesigned as a bubble column staged with two different types of thefibrous catalysts has been proposed for the simultaneous bromate andnitrate removal from polluted waters. [ABSTRACT FROM AUTHOR]

Employing a suitable cocatalyst is very important to improve photocatalytic H 2 evolution activity. Herein, two plasmonic cocatalysts, Au nanoparticles and TiN nanoparticles were in-situ coupled over the g-C 3 N 4 nanotube to form a ternary 0D/0D/1D Au/TiN/g-C 3 N 4 composite via a successive thermal polycondensation and chemical reduction method. The g-C 3 N 4 nanotube acted as a support for the growth of Au and TiN nanoparticles, leading to intimate contact between g-C 3 N 4 nanotube with Au nanoparticles and TiN nanoparticles. As a result, multiple interfaces and dual-junctions of Au/g-C 3 N 4 Schottky-junction and TiN/g-C 3 N 4 ohmic-junction were constructed, which helped to promote the charged carriers' separation and enhanced the photocatalytic performance. Furthermore, loading plasmonic cocatalysts of Au nanoparticles and TiN nanoparticles can enhance the light absorption capacity. Consequently, the Au/TiN/g-C 3 N 4 composite exhibited significantly enhanced photocatalytic H 2 evolution activity (596 μmol g−1 h−1) compared to g-C 3 N 4 or binary composites of Au/g-C 3 N 4 and TiN/g-C 3 N 4. This work highlights the significant role of cocatalysts in photocatalysis. [Display omitted] • LSPR enhanced 0D/0D/1D Au/TiN/g-C 3 N 4 composite was prepared. • Au and TiN dual plasmonic cocatalysts provided more active sites. • Double junctions were formed to offer dual electron transfer route. • Au/TiN/g-C 3 N 4 composite exhibited enhanced photocatalytic H 2 evolution activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cobalt supported the nitrogen-doped carbon catalyst developed from the zeolitic-imidazolate framework. • The prepared catalyst displayed lower overpotential (44 mV) with 94 mV dec-1 tafel slop for the hydrogen evolution reaction. • The prepared catalyst also demonstrated the faster conversion of 4-nitrophenol to 4-aminophenol. Transition metal-supported carbon hybrid structures have evolved for various catalytic applications. However, few studies have reported the use of the same catalyst for both electrochemical hydrogen evolution reaction (HER) and chemical reduction of 4-nitrophenol (4-NP) with excellent catalytic performance and long-term stability. Herein, we present a facile approach to obtain cobalt nanoparticles supported by nitrogen-doped carbon nanotube (Co@N-CNT) with yarn bundle morphology. The use of zeolitic-imidazolate frameworks (ZIFs) is an easy approach to control and design a desired hybrid structure under 5% H 2 /Ar at 900 °C due to selective metal ions with an organic linker. In particular, the number of catalytic active sites in cobalt metal and the high conductance of carbon showed a synergetic effect and turned the hybrid structure into an optimal catalyst candidate for HER and reduction of 4-NP. In addition, interfacial physicochemical interaction within the N-CNT and Co metal promptly accelerated the electrocatalytic performance at overpotential of 44 mV and achieved a current density of 10 mA cm−2 with continued running of stability cycles for 30 h. Furthermore, a pseudo-first-order kinetic constant of 0.68 min−1 was achieved for the reduction of 4-NP. [ABSTRACT FROM AUTHOR]

• The Zr-modified CeTiO x mixed oxide catalyst was reduced by H 2 for NH 3 -SCR. • R-CZT-20/1 catalyst exhibited outstanding low-temperature activity and excellent SO 2 resistance. • The R-CZT-20/1 sample enriched Ce3+, oxygen vacancies, strong synergistic effect between Ce-Zr-Ti. • The reduced R-CZT-20/1 obeyed the L-H mechanism. The Zr-modified CeTiO x mixed oxide catalyst with good NH 3 -SCR activity and SO 2 resistance was synthesized and reduced by H 2. Performance test revealed that the obtained R-CZT-20/1 (Ce: Zr: Ti = 20: 1: 100) catalyst exhibited outstanding low-temperature activity after H 2 reduction treatment, which achieved upon 98% NO conversion at 200–350 °C. Remarkably, it possessed excellent SO 2 resistance as well as good reversibility, with the activity decreased from 100% to 96%. Meanwhile, R-CZT-20/1 possessed more surface acid sites and oxygen defects, which promoted the chemical adsorption and activation of NO and NH 3 on the catalyst surface. XPS results confirmed that R-CZT-20/1 enriched Ce3+, accelerated the electron transfer between Ce3++ Ti4+ → Ce4++ Ti3+, and generated a large number of oxygen vacancies. Moreover, there is strong synergistic effect between Ce-Zr-Ti, which might be the reason for the excellent SO 2 resistance. Among them, the presence of Zr facilitated the favorable process. In situ DRIFTS experiments indicated that the unreduced catalysts followed E-R and L-H mechanism at low and high temperatures, respectively, while R-CZT-20/1 obeyed only the L-H mechanism. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Supported by a conductive and larger specific area CNT/BC 3D nanocomposite film. • Copper-based electrode synthesized via in situ chemical reduction in solution. • Synergistic effect of CNT and Cu favors the transmission of charge. • NaBH 4 is more favorable to the stability of ECR-CO 2 as reducing agent. A CNT/Bacterial Cellulose (BC) nanocomposite with a large surface area and conductive properties was in-situ cultivated to retain the native 3D nanofibril network. The Cu-Cu x O/CNT/BC nanocomposite electrode was in-situ fabricated via reduction with the CNT/BC composite as a support, comparing KBH 4 and NaBH 4 as a reducing agent to obtain efficient electrodes for CO 2 reduction (ECR-CO 2). Both electrodes exhibited higher performance than the traditional carbon cloth or pristine BC supported Cu-based catalysts for conversion of ECR-CO 2 to CO and C 2 H 4. The CNT/BC as a support provided not only more active sites for copper catalyst but also increased the charge transfer and selective performance of C 2 H 4 product, due to the synergistic effect of CNT and copper. The smaller honeycomb and dendritic lamellar crystal morphology of the obtained Cu-Cu x O/CNT/BC NaBH4 electrode possessed a large electrochemical specific surface area, providing more active sites for ECR-CO 2. The double-layer capacitance and the current density reached 11.8 mF cm−2 and 33.3 mA cm−2, respectively. At a potential of −1.5 V RHE , the Faraday efficiency (FE CO + FE C2H4) was 66%. Moreover, the Cu-Cu x O/CNT/BC nanocomposite electrode was very stable, and withstood tolerance in ECR-CO 2 for more than 20 h. This study possibly will provide a new design for catalyst support on CNT/BC substrate to regulate advanced catalysts/electrodes for different applications, especially to ECR-CO 2 in terms of higher charge transport properties, lower contact resistance, higher current density, and more stable CO 2 electroreduction performance. [ABSTRACT FROM AUTHOR]

Abstract: Single crystalline SnO micro-disks, synthesized by a carbothermal reduction process, exhibited a nearly 1000-fold increase in resistance upon exposure to 100ppm of NO2 without addition of catalysts or dopants nor the existence of nano-sized dimensions. Moreover, the SnO displayed a greater than 100-fold selectivity to NO2 over potential interferents including CO, H2 and CH4. The high sensor signal and exceptional selectivity for this novel sensor material are attributed to the existence of a high density of active lone pair electrons on the exposed (001) planes of the single crystalline SnO disks. This, thereby, identifies new means, not utilizing nano-dimensions, to achieve high gas sensitivity. [Copyright &y& Elsevier]

The effect of a new catalyst system composed of traditional three way catalyst converter and adsorber-reduction catalysis converter on the emission characteristics and BSFC (Breake Specific Fuel Consumption- BSFC)of a lean burn gasoline engine operated were investigated in this paper under different schemes of catalyst converter arrangement and different speeds and loads. The results show that the position of Three Way Catalyst is before the NOx adsorber Catalyst was the best scheme of catalyst converter arrangement. Which has the highest converter efficiency of reduction NOx emission in lean burn gasoline engine. The effects of speed on the exhaust emission and BSFC were also related to the ratio of lean burn time to rich burn time and the absolute value of both time of the adsorber-reduction catalyst converter. The load of the engine was the main influential factor to the exhaust emission characteristics and BSFC of lean burn gasoline engine, and the more load of the engine was, the more NOx emission, the less NOx conversion rate (CNOx) and the better BSFC were. [ABSTRACT FROM AUTHOR]

SO uptake, thermal regeneration and the reduction of SO via H(g) over ceria-promoted NSR catalysts were investigated. Sulfur poisoning and desulfation pathways of the complex BaO/Pt/CeO/AlO NSR system was investigated using a systematic approach where the functional sub-components such as AlO, CeO/AlO, BaO/AlO, BaO/CeO/AlO, and BaO/Pt/AlO were studied in a comparative fashion. Incorporation of ceria significantly increases the S-uptake of AlO and BaO/AlO under both moderate and extreme S-poisoning conditions. Under moderate S-poisoning conditions, Pt sites seem to be the critical species for SO oxidation and SO storage, where BaO/Pt/AlO and BaO/Pt/CeO/AlO catalysts reveal a comparable extent of sulfation. After extreme S-poisoning due to the deactivation of most of the Pt sites, ceria domains are the main SO storage sites on the BaO/Pt/CeO/AlO surface. Thus, under these conditions, BaO/Pt/CeO/AlO surface stores more sulfur than that of BaO/Pt/AlO. BaO/Pt/CeO/AlO reveals a significantly improved thermal regeneration behavior in vacuum with respect to the conventional BaO/Pt/AlO catalyst. Ceria promotion remarkably enhances the SO reduction with H(g). [ABSTRACT FROM AUTHOR]

Silica-supported sulfonic acid–functional ionic liquid (Si-[SbSipim][PF6]) was found to be an effective catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-ones via a one-pot, three-component Biginelli reaction. The catalyst could be easily separated and reused six times without noticeable reduction inactivity. The process was simple and proceeded in excellent yields. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications® to view the free supplemental file. [ABSTRACT FROM AUTHOR]

A strategy for the control of electron density at a metal center is reported, which uses a remote chemical switch involving second-sphere Lewis acid binding that modulates electron density in the first coordination sphere. Binding of the Lewis acid B(C6F5)3 at remote nitrogen positions of a bipyrazine-diarylplatinum(II) complex accelerates biaryl reductive elimination by a factor of 64,000. [ABSTRACT FROM AUTHOR]

Abstract: A facile and rapid method for the parallel synthesis of a series of secondary and tertiary amines by the direct reductive amination of aldehydes and ketones with Hantzsch ester under solvent- and catalyst-free has been developed. The scope and limitation of this method are described. [Copyright &y& Elsevier]

Highlights: [•] AuNPs can be immobilized on dead yeast cell by reacting Pichia pastoris with HAuCl4. [•] NH2 and OH were demonstrated to play a crucial role in the biosorption process. [•] Mannocarolose may be responsible for the bioreduction of [AuCl4]−. [•] Au/P. pastoris exhibited good catalytic activity for the reduction of 4-NP. [•] The catalytic activity is closely related to the interaction between AuNPs and yeast. [Copyright &y& Elsevier]

Highlights: [•] A series of neutral Ru(II) complexes derived from reduced imine ligands containing aromatic sulfonamide was synthesized. [•] The synthesized compounds were characterized by different methods such as NMR, FT-IR, and elemental analysis. [•] The complexes have been used as catalyst for the TH of p-substitute acetophenone derivatives. [Copyright &y& Elsevier]

Abstract: The efficient conversion of solar energy to transportable, combustible fuels and chemical feedstock remains an important challenge for synthetic chemists. This daunting task requires a delicate balance of light absorption, electron transfer, charge separation, and catalysis of bond breaking and bond forming reactions. This review highlights our recent studies of supramolecular systems coupling Ru(II) or Os(II) polyazine chromophores with directional charge transfer excited states to catalytically active cis-RhCl2 or cis-PtCl2 metal centers. Comparison to similar supramolecules is provided to highlight design constraints. These supramolecules absorb strongly in the low energy visible and exhibit emissive Ru→BL 3MLCT excited states. Systems with catalytic Rh(III) undergo photoinitiated electron collection (PEC) at the Rh center via Ru or Os→Rh metal-to-metal charge transfer (MMCT) state, while those with cis-PtCl2 moieties form charge-separated (CS) excited states. Electrochemical studies provide a means for understanding relative orbital energetics as well as predicting the existence of a charge-separated state or the propensity for photoinitiated electron collection. Emission spectroscopy including time resolved measurements provides support of these interstate dynamics. Detailed kinetic analysis by photophysical studies indicates formation of the 3MMCT states and 3CS states occurs via intramolecular electron transfer with rate constants on the order of 106–107 s−1. The complexes are active photocatalysts which absorb lower energy visible light, and provide high quantum efficiency and long term stability for the reduction of water to hydrogen. Catalytic activities are modulated by component modification and system parameters and are often dependent upon driving forces for intramolecular electron transfer, reductive excited state quenching, and component modification. [Copyright &y& Elsevier]

The electrochemical performance of the dual-catalyst system composed of nickel phthalocyanine (NiPc) and nano-manganese dioxide (nano-MnO2) for O2reduction in alkaline media was studied. The electrocatalytic activities for oxygen reduction were evaluated by cyclic voltammeter method and linear sweep voltammeter method. The optimum ratio of NiPc and nano-MnO2was established by Job's method. The methanol tolerance property of dual catalysts with the optimum ratio was tested. The results implied that the dual catalysts showed excellent ORR activity involving a four-electron mechanism, with a Tafel slope of about 130 mV, indicating a one-electron process in the rate-determining step. [ABSTRACT FROM AUTHOR]

Abstract: A series of Al, Mn, Cu and Fe metal-containing mesoporous carbon catalysts were synthesized for catalyzing selective reduction of carbon–carbon double bond in 4-nitrostilbene analogs bearing nitro group with hydrazine hydrate. The results indicated that the reduction reaction was able to be achieved successfully between carbon–carbon double bond and nitro group. The efficient method has been developed for the reduction of C C double bonds with diimide, catalytically generated in situ from hydrazine hydrate by the synthesized catalysts. The 0.15Al–MC1 as heterogeneous catalyst exhibited the highest catalysis activity and chemoselectivity in all synthesized catalysts. In the presence of 0.15Al–MC1, the reduction of carbon–carbon double bond in 4-nitrostilbene derivatives was up to 99% yield and >99% chemoselectivity at 70°C in ethanol. On the other hand, the high selective reduction of nitro group in 4-nitrostilbenes was also facile to be achieved with hydrazine hydrate, active carbon and FeCl3·6H2O under inert atmosphere. [Copyright &y& Elsevier]

Abstract: A new methodology is proposed and tested by Density Functional Theory (DFT) calculations to reduce N2 to NH3 and N2H4 using H2 in the presence of [Mo{(NHCH2CH2)3N}] and organic co-catalysts under mild experimental conditions. The calculated Gibbs free energies of the fundamental reactions to form various intermediates and transition state molecules suggest that the proposed catalytic cycle is viable to produce NH3 and N2H4, however NH3 formation is more feasible than N2H4. Formation of six coordinate [Mo]-H intermediates have also been predicted. The direct contact of H2 with [N2-Mo{(NHCH2CH2)3N}] catalyst can be avoided by using organic co-catalysts to prevent the competition in binding between N2 and H2 with [Mo{(NHCH2CH2)3N}] catalyst. [Copyright &y& Elsevier]

Abstract: Composite catalysts Fe0.3Co0.7-doped carbon aerogel have been in situ synthesized by chemical reduction method and successfully employed in the hydrolysis of NH3BH3 (AB) at room temperature. The mass percent of the doped Fe0.3Co0.7 alloys can reach to the maximum value of 40 wt%. The prepared catalysts exhibit excellent catalytic activity, especially for the specimen of 40 wt% Fe0.3Co0.7/C, which shows high catalytic activity and long durability. Its maximum hydrogen generation rate is as high as 13,695.6 ml min−1 g−1 at 298 K and the activation energy is only 20.83 kJ mol−1. Besides, this catalyst possesses preferable cycling stability at room temperature. The low cost, high catalytic activity and enhanced cycling stability can make it have a bright future in the application field of fuel chemistry. [Copyright &y& Elsevier]

Abstract: Ni catalysts supported on La2O3–SiO2 were tested in the steam reforming of glycerol. The catalysts were prepared by the wet impregnation method and characterized by energy dispersive X-ray spectroscopy (EDX), nitrogen physisorption (BET method), X-ray diffraction (XRD), temperature programmed reduction with H2 (TPR) and in situ XRD. XRD and TPR analysis indicated several Ni species in the samples: NiO, LaNiO3 and La2NiO4. From the analyses of XRD and in situ XRD data it was also possible to estimate the sizes of the NiO and Ni0 crystallites, respectively, which suggested a greater or lesser degree of dispersion of these species on the various supports. The catalytic tests were performed in a fixed bed reactor containing 150mg catalyst at 600°C, with an inlet water:glycerol ratio of 3:1. These tests showed that, the deposition of carbon on the catalyst during the reaction fell steadily as the proportion of La2O3 in the support increased. This may be related to the formation of La carbonate as the CO2 is adsorbed on La2O3 on the support. [Copyright &y& Elsevier]

Abstract: WO x –ZrO2 support was calcined at various temperatures for obtaining controllable activity of copper catalysts for NO x reduction by ammonia. The temperature window of copper catalyst for over 80% NO x conversion shifts from 180–300 to 230–350 °C by elevating the calcination temperature of WO x –ZrO2 support from 500 to 600 °C, due to the increased Brønsted acidity and reduced structure and electronic interactions between copper oxides and tungsten oxides arising from the polymerization of WO x clusters on surface of support. Calcining WO x –ZrO2 support at 700 °C leads to the reduced redox property of copper oxides on the Cu–O–W interface and the formation of bulk-like CuO, results in a low activity of catalyst. [Copyright &y& Elsevier]

Abstract: The present study aims to investigate influence of pre-heating of CH4 on the growth of multi-walled carbon nanotubes (MWCNTs) using Fe2O3 particles as catalyst precursor. Equilibrium thermodynamic analyses in the systems of FeCOH and CH were performed to better understand the reduction of Fe2O3 by CH4 and to identify intermediate species which might promote growth of MWCNTs at the temperature range of 1000–1300K. It was found that CH4 acted as reducing agent for Fe2O3 catalyst precursor which transformed to Fe3O4, FeO, Fe and Fe3C phases. This result was found to be in agreement with the thermodynamic prediction at 1200 and 1300K. SEM-EDS analysis revealed that un-preheated CH4 yielded MWCNTs at 1200K and a dense C coating at 1300K. It was also observed that carbon was not formed at temperatures in the range of 1050–1150K. Whereas, MWCNTs were grown at this temperature range from CH4 pre-heated at 1200K. This result was attributed to the intermediate hydrocarbons, especially to C6H6, formed during pre-heating stage as thermodynamic analysis suggested. Mean diameter of the synthesized tubes was found to increase with growth time and temperature. [Copyright &y& Elsevier]

Abstract: Naphthenic acid (NA) present in crude oil leads to corrosion problems within oil refineries. The objective of this study is to reduce total acid number (TAN) from NA using a catalyst-free supercritical methanol (SC-MeOH), a process novel in this area. The reaction was carried out in an 8.8mL batch reactor fabricated from Hastelloy C-276 with respective design temperature and pressure of 500°C and 50MPa. The ability of SC-MeOH to reduce TAN was explored at temperatures from 300 to 350°C and methanol partial pressure (MPP) of 10MPa. Experimental results revealed that TAN removal was 99.77% at a temperature of 350°C, MPP of 10MPa and reaction time of 60min. The TAN removal followed first order kinetics, with Arrhenius parameters of activation energy 5.78kcal/ mol and a pre-exponential factor 1.56s−1. These results suggest that SC-MeOH is capable of reducing TAN from NA with no use of catalyst or additives. [Copyright &y& Elsevier]

The article offers information on the recent developments in flavin-based catalysis. It informs that flavins can be excited by irradiation with the help of visible light which makes them stronger catalysts for oxidative processes. It also informs that flavins can be used in the reduction of olefins by catalyzing the formation of diimide as flavins show high thermal and chemical stability in the reduction processes.

Abstract: This paper reports on the application of hydroxide ion conducting layered double hydroxides (LDHs) to the catalyst layer in an alkaline fuel cell for the improvement of the oxygen reduction reaction (ORR) at the triple phase boundary (TPB) in the catalyst layer. Ni–Al LDH intercalated with (Ni–Al LDH) and Mg–Al LDH were used in this study. Ni–Al LDH showed higher ionic conductivity than Mg–Al LDH under R.H. of 80%. The catalyst layers with and without hydroxide ion conducting LDHs was prepared, and a half-cell using the prepared catalyst layers was fabricated. The addition of LDHs to the catalyst layer increased the reduction current for ORR, indicating that hydroxide ion conducting LDHs introduced OH− conducting paths and increased TPB region within the catalyst layer. Above all, the addition of Ni–Al LDH to the catalyst layer more effectively increased the reduction current for ORR than the addition of Mg–Al LDH. The performance of the alkaline-type direct ethanol fuel cell was also improved. These experimental results indicate that high hydroxide ion conducting Ni–Al LDH effectively increased TPB region within the catalyst layer. [Copyright &y& Elsevier]

Abstract: We present a theoretical study on the effects of key catalyst layer (CL) design parameters on the cold start behavior of a polymer electrolyte fuel cell (PEFC) using a three-dimensional transient cold start model developed in a previous study [1,2]. Among several CL design parameters, we adopt the ionomer fraction (ɛ I) and weight ratio of Pt to carbon support (wt%Pt – C) in the cathode CL as CL design variables for this study. Therefore, other design parameters such as CL thickness and the oxygen reduction reaction (ORR) kinetic parameter are accordingly adjusted due to changes in ɛ I and wt%Pt – C for cold start simulations. The calculated results confirm that these two design parameters provide control of the ice storage capacity and water absorption potential of the cathode CL, and consequently have a substantial influence on the cold start behavior of a PEFC. We provide a guideline to design and optimize a cathode CL and membrane electrode assembly (MEA) for improved PEFC cold start capability. [Copyright &y& Elsevier]

Abstract: We investigate the effects of initial sulfur loadings on the desulfation chemistry and subsequent final activity of a commercial LNT catalyst. Identical total amounts of SO2 are applied to the samples, albeit with the frequency of desulfation varied. The results indicate that performance is better with less frequent desulfations. The greater the amount of sulfur deposited before desulfation, the more amount of SO2 evolution before H2S is observed during desulfation, which can be explained by two sequential reactions; initial conversion of sulfate to SO2, followed by the reduction of SO2 to H2S. After completing all sulfation/desulfation steps, the sample with only a single desulfation results in a fairly uniform sulfur distribution along the z-axis inside of the monolith. We expect that the results obtained in this study will provide useful information for optimizing regeneration strategies in vehicles that utilize the LNT technology. [Copyright &y& Elsevier]

Two types of bead-shaped stable heterogeneous nanoparticle catalysts, viz. polymer-supported poly(styrene) functionalized with poly(vinylimidazole) immobilized silver nanoparticles (PS-PVIm-AgNPs) were prepared from poly(styrene)-co-poly(N-vinylimidazole) polymer matrices derived from 2% (Type-I) and 10% (Type-II) cross-linking monomer divinylbenzene and AgNO3 as a metal precursor. The appearance of surface plasmon resonance peak at 422 nm in UV and AgN(str,ring) peaks noticed at 1664 cm−1 for Type-I and 1668 cm−1 for Type-II catalysts in FT-IR confirms the immobilization of AgNPs onto PS-PVIm. The SEM and EDAX results prove that the Type-I catalyst has heterogeneous morphology with more white patches and enhanced amount of surface nitrogen and AgNPs than Type-II. The size of the AgNPs on Type-I and Type-II catalysts was measured as 10 nm and 14.6 nm from XRD, respectively. The comparative catalytic study for the reduction of 4-nitrophenol reveals that the pseudo-first order rate constant (kobs) for Type-I catalyst was relatively superior (kobs=5.12×10−4) than Type-II (kobs=1.20×10−4) due to the addition of high cross-linking load in Type-II. For the same reaction with Type-I catalyst, the variation of [substrate], [catalyst] and [NaBH4] was directly proportional to kobs. The stability and reusability of the catalyst were observed good and sustained even at six cycles. [Copyright &y& Elsevier]

Abstract: A simple and convenient method for generating and immobilizing gold NPs into polyethylene glycol-polyurethane (PEGPU) matrices is presented. The gold NP immobilized PEGPU (Au NP-PEGPU) hydrogel matrices are easy to handle and can be used as catalysts. The efficiency, reusability and durability of the Au NP-PEGPU catalyst matrices were investigated using the reduction of 4-nitroaniline (4NA) to p-phenylenediamine (p-PDA) by sodium borohydride in the presence of the catalyst as a test reaction. The Au NPs in the PEGPU matrix got aggregated after 3 cycles of catalysis but dispersion could be regenerated by the addition of N-bromosuccinimide (NBS). After this regeneration process the Au NPs-PEGPU matrix showed excellent efficiency without any aggregation, leaching or degradation. The reusability of the catalyst for 28 cycles yielding a total turnover number of 3220 and turn over frequency of 0.152s−1 is demonstrated. [Copyright &y& Elsevier]

A functional GO/AgNPs nanocomposite was obtained by in situ reduction of positively charged AgNO3 precursors which were adsorbed on the negatively charged surface of GO through electrostatic attraction. GO/Ag −Fe3O4 magnetic nanoparticles (GAMNs) were generated via an amidation reaction in the presence of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide and N-hydroxysuccinnimide for the first time. The catalysis property of the nanocomposite was studied by degrade 4-nitrophenol. The characterized results proved that AgNPs and Fe3O4 have been successfully decorated on GO nanosheets. The GAMNs possess high catalytic capacity and good reusability, and exhibit great potential in environmental pollutant degradation. [Copyright &y& Elsevier]

The article offers information regarding the use of heterogeneous catalysts, such as palladium on carbon for several oxidation and reduction reactions. It discusses the use of DNA-mediated palladium nanoparticles as an efficient catalyst. It also investigates ways of using the waste DNA from discarded industrial salmon milt.

The article offers information regarding hydrogenative reduction of carbon dioxide which provides carbon dioxide-neutral alternatives to fossil fuels. It explores the possibility of for the conversion of solar energy into a convenient fuel, renewable-energy future, by direct, light-driven reduction of carbon dioxide into MeOH. It discusses the use of enzyme catalysts or homogeneous catalysts for the reduction process.

Three types of new amphiphilic poly(quaternary ammonium) dendrimer catalysts were prepared from poly(propylene imine) generation-2 (PPI-G2) dendrimer with 3 types of alkyl halides having varied chain length. The C一H stretching at 2922 and 2853 cm−1 and C一N+ stretching at 1108 cm−1 confirmed the attachment of alkyl chains and generation of poly(quaternary ammonium) ions at the dendrimer surface. Their 1H and 13C NMR spectra also supported such confirmations. The hydrophobicity of these 3 poly(quaternary ammonium) based dendrimer catalysts was determined by the static water contact angle (θ). The catalyst derived from attachment of long alkyl chain viz., PPI-G2-(C16H33)16 (CH3)8一N+Cl− showed an increased contact angle (77.5 θ) thus proving high hydrophobicity. Their catalytic activity was evaluated through reduction of citronellal under pseudo-first order condition at ambient temperature. The rate constant (kobs), of the catalyst containing medium length alkyl chain viz., PPI-G2-(C12H25)16 (CH3)8一N+Cl− was higher than those containing short and long alkyl chains due to its well-balanced amphiphilic character. It gave 100% selectivity/activity compared to commercial single-site phase transfer catalyst for citronellal reduction. The effect of [substrate], [catalyst], [NaOH], and [NaBH4] on the rate of the reaction was studied and the results were discussed. [ABSTRACT FROM AUTHOR]

We propose a mechanistic model for three-stage dehydrogenationof ammonia–borane (AB) catalyzed by Shvo’s cyclopentadienone-ligatedruthenium complex. We provide evidence for a plausible mechanism forcatalyst deactivation and the transition from fast catalysis to slowcatalysis and relate those findings to the invention of a second-generationcatalyst that does not suffer from the same deactivation chemistry.The primary mechanism of catalyst deactivation is borazine-mediatedhydroboration of the ruthenium species that is the active oxidantin the fast catalysis case. This transition is characterized by achange in the rate law for the reaction and changes in the apparentresting state of the catalyst. Also, in this slow catalysis situation,we see an additional intermediate in the sequence of boron, nitrogenspecies, aminodiborane. This occurs with concurrent generation ofNH3, which itself does not strongly affect the rate ofAB dehydrogenation. [ABSTRACT FROM AUTHOR]