Open AccessArticle
Selective Hydrogenation of Concentrated Vinyl Acetylene Mixed C4 by Modified Pd Catalysts: Effect of Cu
Catalysts 2016, 6(12), 199; doi:10.3390/catal6120199 (registering DOI) -
Abstract
The Pd and Pd-Cu on alumina catalysts were tested for hydrogenation of vinyl acetylene in mixed C4 in a circulating tubular reactor. The results showed that adding proper amounts of Cu improved the reaction activity, but inhibited 1,3-butadiene selectivity. Moreover, the presence of
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The Pd and Pd-Cu on alumina catalysts were tested for hydrogenation of vinyl acetylene in mixed C4 in a circulating tubular reactor. The results showed that adding proper amounts of Cu improved the reaction activity, but inhibited 1,3-butadiene selectivity. Moreover, the presence of Cu retarded the carbon deposition on catalysts during the reaction. Temperature programmed oxidation (TPO), Temperature programmed reduction (TPR), H2 chemisorption, and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the catalysts. The characterization suggested both geometric and electronic modifications. Full article
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Open AccessArticle
Facile Synthesis of MnPO4·H2O Nanowire/Graphene Oxide Composite Material and Its Application as Electrode Material for High Performance Supercapacitors
Catalysts 2016, 6(12), 198; doi:10.3390/catal6120198 (registering DOI) -
Abstract
In this work, we reported a facile one-pot hydrothermal method to synthesize MnPO4·H2O nanowire/graphene oxide composite material with coated graphene oxide. Transmission electron microscopy and scanning electron microscope were employed to study its morphology information, and X-ray diffraction was
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In this work, we reported a facile one-pot hydrothermal method to synthesize MnPO4·H2O nanowire/graphene oxide composite material with coated graphene oxide. Transmission electron microscopy and scanning electron microscope were employed to study its morphology information, and X-ray diffraction was used to study the phase and structure of the material. Additionally, X-ray photoelectron spectroscopy was used to study the elements information. To measure electrochemical performances of electrode materials and the symmetry cell, cyclic voltammetry, chronopotentiometry and electrochemical impedance spectrometry were conducted on electrochemical workstation using 3 M KOH electrolytes. Importantly, electrochemical results showed that the as-prepared MnPO4·H2O nanowire/graphene oxide composite material exhibited high specific capacitance (287.9 F·g−1 at 0.625 A·g−1) and specific power (1.5 × 105 W·kg−1 at 2.271 Wh·kg−1), which is expected to have promising applications as supercapacitor electrode material. Full article
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Open AccessReview
Proton Exchange Membrane Fuel Cell Reversal: A Review
Catalysts 2016, 6(12), 197; doi:10.3390/catal6120197 -
Abstract
The H2/air-fed proton exchange membrane fuel cell (PEMFC) has two major problems: cost and durability, which obstruct its pathway to commercialization. Cell reversal, which would create irreversible damage to the fuel cell and shorten its lifespan, is caused by reactant starvation,
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The H2/air-fed proton exchange membrane fuel cell (PEMFC) has two major problems: cost and durability, which obstruct its pathway to commercialization. Cell reversal, which would create irreversible damage to the fuel cell and shorten its lifespan, is caused by reactant starvation, load change, low catalyst performance, and so on. This paper will summarize the causes, consequences, and mitigation strategies of cell reversal of PEMFC in detail. A description of potential change in the anode and cathode and the differences between local starvation and overall starvation are reviewed, which gives a framework for comprehending the origins of cell reversal. According to the root factor of cell starvation, i.e., fuel cells do not satisfy the requirements of electrons and protons of normal anode and cathode chemical reactions, we will introduce specific methods to mitigate or prevent fuel cell damage caused by cell reversal in the view of system management strategies and component material modifications. Based on a comprehensive understanding of cell reversal, it is beneficial to operate a fuel cell stack and extend its lifetime. Full article
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Open AccessReview
Application, Deactivation, and Regeneration of Heterogeneous Catalysts in Bio-Oil Upgrading
Catalysts 2016, 6(12), 195; doi:10.3390/catal6120195 -
Abstract
The massive consumption of fossil fuels and associated environmental issues are leading to an increased interest in alternative resources such as biofuels. The renewable biofuels can be upgraded from bio-oils that are derived from biomass pyrolysis. Catalytic cracking and hydrodeoxygenation (HDO) are two
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The massive consumption of fossil fuels and associated environmental issues are leading to an increased interest in alternative resources such as biofuels. The renewable biofuels can be upgraded from bio-oils that are derived from biomass pyrolysis. Catalytic cracking and hydrodeoxygenation (HDO) are two of the most promising bio-oil upgrading processes for biofuel production. Heterogeneous catalysts are essential for upgrading bio-oil into hydrocarbon biofuel. Although advances have been achieved, the deactivation and regeneration of catalysts still remains a challenge. This review focuses on the current progress and challenges of heterogeneous catalyst application, deactivation, and regeneration. The technologies of catalysts deactivation, reduction, and regeneration for improving catalyst activity and stability are discussed. Some suggestions for future research including catalyst mechanism, catalyst development, process integration, and biomass modification for the production of hydrocarbon biofuels are provided. Full article
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Open AccessReview
New Frontiers in the Catalytic Synthesis of Levulinic Acid: From Sugars to Raw and Waste Biomass as Starting Feedstock
Catalysts 2016, 6(12), 196; doi:10.3390/catal6120196 -
Abstract
Levulinic acid (LA) is one of the top bio-based platform molecules that can be converted into many valuable chemicals. It can be produced by acid catalysis from renewable resources, such as sugars, lignocellulosic biomass and waste materials, attractive candidates due to their abundance
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Levulinic acid (LA) is one of the top bio-based platform molecules that can be converted into many valuable chemicals. It can be produced by acid catalysis from renewable resources, such as sugars, lignocellulosic biomass and waste materials, attractive candidates due to their abundance and environmentally benign nature. The LA transition from niche product to mass-produced chemical, however, requires its production from sustainable biomass feedstocks at low costs, adopting environment-friendly techniques. This review is an up-to-date discussion of the literature on the several catalytic systems that have been developed to produce LA from the different substrates. Special attention has been paid to the recent advancements on starting materials, moving from simple sugars to raw and waste biomasses. This aspect is of paramount importance from a sustainability point of view, transforming wastes needing to be disposed into starting materials for value-added products. This review also discusses the strategies to exploit the solid residues always obtained in the LA production processes, in order to attain a circular economy approach. Full article
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Open AccessArticle
The Preparation of Cu-g-C3N4/AC Catalyst for Acetylene Hydrochlorination
Catalysts 2016, 6(12), 193; doi:10.3390/catal6120193 -
Abstract
A novel catalyst based on g-C3N4/activated carbon was prepared by adding CuCl2. The catalytic performance of the as-prepared catalyst was investigated in the acetylene hydrochlorination reaction. X-ray photoelectron spectroscopy, temperature programmed desorption, low temperature N2 adsorption/desorption
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A novel catalyst based on g-C3N4/activated carbon was prepared by adding CuCl2. The catalytic performance of the as-prepared catalyst was investigated in the acetylene hydrochlorination reaction. X-ray photoelectron spectroscopy, temperature programmed desorption, low temperature N2 adsorption/desorption (Brunauer–Emmett–Teller), and thermal gravity analysis showed that Cu-g-C3N4/AC significantly enhanced the catalytic performance of the original catalyst by increasing the relative pyrrolic N content. Cu-g-C3N4/AC also affected the adsorption of hydrogen chloride and acetylene, as well as inhibited the coke deposition during acetylene hydrochlorination. Full article
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Open AccessFeature PaperReview
Tandem Reactions Combining Biocatalysts and Chemical Catalysts for Asymmetric Synthesis
Catalysts 2016, 6(12), 194; doi:10.3390/catal6120194 -
Abstract
The application of biocatalysts in the synthesis of fine chemicals and medicinal compounds has grown significantly in recent years. Particularly, there is a growing interest in the development of one-pot tandem catalytic systems combining the reactivity of a chemical catalyst with the selectivity
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The application of biocatalysts in the synthesis of fine chemicals and medicinal compounds has grown significantly in recent years. Particularly, there is a growing interest in the development of one-pot tandem catalytic systems combining the reactivity of a chemical catalyst with the selectivity engendered by the active site of an enzyme. Such tandem catalytic systems can achieve levels of chemo-, regio-, and stereo-selectivities that are unattainable with a small molecule catalyst. In addition, artificial metalloenzymes widen the range of reactivities and catalyzed reactions that are potentially employable. This review highlights some of the recent examples in the past three years that combined transition metal catalysis with enzymatic catalysis. This field is still in its infancy. However, with recent advances in protein engineering, catalyst synthesis, artificial metalloenzymes and supramolecular assembly, there is great potential to develop more sophisticated tandem chemoenzymatic processes for the synthesis of structurally complex chemicals. Full article
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Open AccessPerspective
Hidden but Possibly Fatal Misconceptions in Photocatalysis Studies: A Short Critical Review
Catalysts 2016, 6(12), 192; doi:10.3390/catal6120192 -
Abstract
This short review paper shows some misconceptions hidden in the discussion on the mechanism of heterogeneous photocatalysis, which may lead to fatal errors in conclusions. Topics described in this review are semiconductor photocatalysis, control experiments for proof of photocatalysis, and converse-proposition pitfalls in
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This short review paper shows some misconceptions hidden in the discussion on the mechanism of heterogeneous photocatalysis, which may lead to fatal errors in conclusions. Topics described in this review are semiconductor photocatalysis, control experiments for proof of photocatalysis, and converse-proposition pitfalls in discussion. Full article
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Open AccessArticle
Mechanistic and Structural Insight to an Evolved Benzoylformate Decarboxylase with Enhanced Pyruvate Decarboxylase Activity
Catalysts 2016, 6(12), 190; doi:10.3390/catal6120190 -
Abstract
Benzoylformate decarboxylase (BFDC) and pyruvate decarboxylase (PDC) are thiamin diphosphate-dependent enzymes that share some structural and mechanistic similarities. Both enzymes catalyze the nonoxidative decarboxylation of 2-keto acids, yet differ considerably in their substrate specificity. In particular, the BFDC from P. putida exhibits very
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Benzoylformate decarboxylase (BFDC) and pyruvate decarboxylase (PDC) are thiamin diphosphate-dependent enzymes that share some structural and mechanistic similarities. Both enzymes catalyze the nonoxidative decarboxylation of 2-keto acids, yet differ considerably in their substrate specificity. In particular, the BFDC from P. putida exhibits very limited activity with pyruvate, whereas the PDCs from S. cerevisiae or from Z. mobilis show virtually no activity with benzoylformate (phenylglyoxylate). Previously, saturation mutagenesis was used to generate the BFDC T377L/A460Y variant, which exhibited a greater than 10,000-fold increase in pyruvate/benzoylformate substrate utilization ratio compared to that of wtBFDC. Much of this change could be attributed to an improvement in the Km value for pyruvate and, concomitantly, a decrease in the kcat value for benzoylformate. However, the steady-state data did not provide any details about changes in individual catalytic steps. To gain insight into the changes in conversion rates of pyruvate and benzoylformate to acetaldehyde and benzaldehyde, respectively, by the BFDC T377L/A460Y variant, reaction intermediates of both substrates were analyzed by NMR and microscopic rate constants for the elementary catalytic steps were calculated. Herein we also report the high resolution X-ray structure of the BFDC T377L/A460Y variant, which provides context for the observed changes in substrate specificity. Full article
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Open AccessArticle
Continuous Packed Bed Reactor with Immobilized β-Galactosidase for Production of Galactooligosaccharides (GOS)
Catalysts 2016, 6(12), 189; doi:10.3390/catal6120189 -
Abstract
The β-galactosidase from Bacillus circulans was covalently attached to aldehyde-activated (glyoxal) agarose beads and assayed for the continuous production of galactooligosaccharides (GOS) in a packed-bed reactor (PBR). The immobilization was fast (1 h) and the activity of the resulting biocatalyst was 97.4 U/g
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The β-galactosidase from Bacillus circulans was covalently attached to aldehyde-activated (glyoxal) agarose beads and assayed for the continuous production of galactooligosaccharides (GOS) in a packed-bed reactor (PBR). The immobilization was fast (1 h) and the activity of the resulting biocatalyst was 97.4 U/g measured with o-nitrophenyl-β-d-galactopyranoside (ONPG). The biocatalyst showed excellent operational stability in 14 successive 20 min reaction cycles at 45 °C in a batch reactor. A continuous process for GOS synthesis was operated for 213 h at 0.2 mL/min and 45 °C using 100 g/L of lactose as a feed solution. The efficiency of the PBR slightly decreased with time; however, the maximum GOS concentration (24.2 g/L) was obtained after 48 h of operation, which corresponded to 48.6% lactose conversion and thus to maximum transgalactosylation activity. HPAEC-PAD analysis showed that the two major GOS were the trisaccharide Gal-β(1→4)-Gal-β(1→4)-Glc and the tetrasaccharide Gal-β(1→4)-Gal-β(1→4)-Gal-β(1→4)-Glc. The PBR was also assessed in the production of GOS from milk as a feed solution. The stability of the bioreactor was satisfactory during the first 8 h of operation; after that, a decrease in the flow rate was observed, probably due to partial clogging of the column. This work represents a step forward in the continuous production of GOS employing fixed-bed reactors with immobilized β-galactosidases. Full article
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Open AccessFeature PaperArticle
New Tailor-Made Alkyl-Aldehyde Bifunctional Supports for Lipase Immobilization
Catalysts 2016, 6(12), 191; doi:10.3390/catal6120191 -
Abstract
Immobilized and stabilized lipases are important biocatalytic tools. In this paper, different tailor-made bifunctional supports were prepared for the immobilization of a new metagenomic lipase (LipC12). The new supports contained hydrophobic groups (different alkyl groups) to promote interfacial adsorption of the lipase and
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Immobilized and stabilized lipases are important biocatalytic tools. In this paper, different tailor-made bifunctional supports were prepared for the immobilization of a new metagenomic lipase (LipC12). The new supports contained hydrophobic groups (different alkyl groups) to promote interfacial adsorption of the lipase and aldehyde groups to react covalently with the amino groups of side chains of the adsorbed lipase. The best catalyst was 3.5-fold more active and 5000-fold more stable than the soluble enzyme. It was successfully used in the regioselective deacetylation of peracetylated d-glucal. The PEGylated immobilized lipase showed high regioselectivity, producing high yields of the C-3 monodeacetylated product at pH 5.0 and 4 °C. Full article
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Open AccessReview
The Applications of Morphology Controlled ZnO in Catalysis
Catalysts 2016, 6(12), 188; doi:10.3390/catal6120188 -
Abstract
Zinc oxide (ZnO), with the unique chemical and physical properties of high chemical stability, broad radiation absorption range, high electrochemical coupling coefficient, and high photo-stability, is an attractive multifunctional material which has promoted great interest in many fields. What is more, its properties
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Zinc oxide (ZnO), with the unique chemical and physical properties of high chemical stability, broad radiation absorption range, high electrochemical coupling coefficient, and high photo-stability, is an attractive multifunctional material which has promoted great interest in many fields. What is more, its properties can be tuned by controllable synthesized morphologies. Therefore, after the success of the abundant morphology controllable synthesis, both the morphology-dependent ZnO properties and their related applications have been extensively investigated. This review concentrates on the properties of morphology-dependent ZnO and their applications in catalysis, mainly involved reactions on green energy and environmental issues, such as CO2 hydrogenation to fuels, methanol steam reforming to generate H2, bio-diesel production, pollutant photo-degradation, etc. The impressive catalytic properties of ZnO are associated with morphology tuned specific microstructures, defects or abilities of electron transportation, etc. The main morphology-dependent promotion mechanisms are discussed and summarized. Full article
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Open AccessArticle
Composition, Structural Evolution and the Related Property Variations in Preparation of Mixed Cesium/Ammonium Acidic Salts of Heteropolyacids
Catalysts 2016, 6(12), 187; doi:10.3390/catal6120187 (registering DOI) -
Abstract
The composition, structural evolution and the related property variations of mixed cesium/ammonium acidic salts of heteropolyacids were investigated in detail by tracking and analyzing the initial precipitates, evaporation residues and the calcined products in their preparation process. Results show that V cannot completely
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The composition, structural evolution and the related property variations of mixed cesium/ammonium acidic salts of heteropolyacids were investigated in detail by tracking and analyzing the initial precipitates, evaporation residues and the calcined products in their preparation process. Results show that V cannot completely enter the heteropolyanions in the initial precipitates when the Cs+ added amount is low, and the increase in Cs+ adding amount improves the substitution of V for Mo in the heteropolyanions. Both the initial precipitates and the evaporation residues are mixtures of cesium and ammonium salts of heteropolyacids before calcination. Thermal treatment causes the decomposition of the ammonium salts and the formation of single-phase solid solutions from mechanical mixtures. The calcined products of the initial precipitates and the evaporation residues vary greatly in textural properties. The determinants of the catalytic performance for the oxidation of methacrolein to methacrylic acid are acidity and specific surface area of the compounds. The increase in specific surface area mainly improves the conversion of methacrolein, but not the selectivity of methacrylic acid. Insufficient acidity caused by high Cs+ content in the compounds is responsible for the low selectivity. Full article
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Open AccessFeature PaperReview
Micro/Mesoporous Zeolitic Composites: Recent Developments in Synthesis and Catalytic Applications
Catalysts 2016, 6(12), 183; doi:10.3390/catal6120183 (registering DOI) -
Abstract
Micro/mesoporous zeolitic composites (MZCs) represent an important class of hierarchical zeolitic materials that have attracted increasing attention in recent years. By introducing an additional mesoporous phase interconnected with the microporosity of zeolites, a hierarchical porous system of MZCs is formed which facilitates molecular
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Micro/mesoporous zeolitic composites (MZCs) represent an important class of hierarchical zeolitic materials that have attracted increasing attention in recent years. By introducing an additional mesoporous phase interconnected with the microporosity of zeolites, a hierarchical porous system of MZCs is formed which facilitates molecular transport while preserving the intrinsic catalytic properties of zeolites. Thus, these materials offer novel perspectives for catalytic applications. Over the years, numerous synthesis strategies toward the formation of MZCs have been realized and their catalytic applications have been reported. In this review, the three main synthesis routes, namely direct synthesis using zeolite precursors, recrystallization of zeolites, and zeolitization of preformed mesoporous materials are thoroughly discussed, with focus on prior works and the most recent developments along with prominent examples given from the literature. In addition, the significant improvement in the catalytic properties of MZCs in a wide range of industrially relevant reactions is presented through several representative cases. Some perspectives for the future development of MZCs are also given. Full article
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Open AccessArticle
Chitosan Aerogel Catalyzed Asymmetric Aldol Reaction in Water: Highly Enantioselective Construction of 3-Substituted-3-hydroxy-2-oxindoles
Catalysts 2016, 6(12), 186; doi:10.3390/catal6120186 -
Abstract
A chitosan aerogel catalyzed asymmetric aldol reaction of ketones with isatins in the presence of water is described. This protocol was found to be environmentally benign, because it proceeds smoothly in water and the corresponding aldol products were obtained in excellent yields with
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A chitosan aerogel catalyzed asymmetric aldol reaction of ketones with isatins in the presence of water is described. This protocol was found to be environmentally benign, because it proceeds smoothly in water and the corresponding aldol products were obtained in excellent yields with good enantioselectivities. Full article
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Open AccessFeature PaperReview
Untangling the Role of the Capping Agent in Nanocatalysis: Recent Advances and Perspectives
Catalysts 2016, 6(12), 185; doi:10.3390/catal6120185 -
Abstract
Capping agents (organic ligands, polymers, surfactants, etc.) are a basic component in the synthesis of metal nanoparticles with controlled size and well-defined shape. However, their influence on the performances of nanoparticle-based catalysts is multifaceted and controversial. Indeed, capping agent can act as a
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Capping agents (organic ligands, polymers, surfactants, etc.) are a basic component in the synthesis of metal nanoparticles with controlled size and well-defined shape. However, their influence on the performances of nanoparticle-based catalysts is multifaceted and controversial. Indeed, capping agent can act as a “poison”, limiting the accessibility of active sites, as well as a “promoter”, producing improved yields and unpredicted selectivity control. These effects can be ascribed to the creation of a metal-ligand interphase, whose unique properties are responsible for the catalytic behavior. Therefore, understanding the structure of this interphase is of prime interest for the optimization of tailored nanocatalyst design. This review provides an overview of the interfacial key features affecting the catalytic performances and details a selection of related literature examples. Furthermore, we highlight critical points necessary for the design of highly selective and active catalysts with surface and interphase control. Full article
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Open AccessFeature PaperArticle
One-Pot Synthesis of (+)-Nootkatone via Dark Singlet Oxygenation of Valencene: The Triple Role of the Amphiphilic Molybdate Catalyst
Catalysts 2016, 6(12), 184; doi:10.3390/catal6120184 -
Abstract
Efficient one-pot catalytic synthesis of (+)-nootkatone was performed from (+)-valencene using only hydrogen peroxide and amphiphilic molybdate ions. The process required no solvent and proceeded in three cascade reactions: (i) singlet oxygenation of valencene according to the ene reaction; (ii) Schenck rearrangement of
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Efficient one-pot catalytic synthesis of (+)-nootkatone was performed from (+)-valencene using only hydrogen peroxide and amphiphilic molybdate ions. The process required no solvent and proceeded in three cascade reactions: (i) singlet oxygenation of valencene according to the ene reaction; (ii) Schenck rearrangement of one hydroperoxide into the secondary β-hydroperoxide; and (iii) dehydration of the hydroperoxide into the desired (+)-nootkatone. The solvent effect on the hydroperoxide rearrangement is herein discussed. The amphiphilic dimethyldioctyl ammonium molybdate, which is also a balanced surfactant, played a triple role in this process, as molybdate ions catalyzed at both Step 1 and Step 3 and it allowed the rapid formation of a three-phase microemulsion system that highly facilitates product recovery. Preparative synthesis of the high added value (+)-nootkatone was thus performed at room temperature with an isolated yield of 46.5%. This is also the first example of a conversion of allylic hydroperoxides into ketones catalyzed by molybdate ions. Full article
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Open AccessArticle
Different Performance of Two Isomeric Phosphinobiphenyl Amidosulfonates in Pd-Catalyzed Cyanation of Aryl Bromides
Catalysts 2016, 6(12), 182; doi:10.3390/catal6120182 -
Abstract
A hydrophilic phosphinobiphenyl amidosulfonate, 2′-(dicyclohexylphosphino)-2- {[(sulfonatomethyl)amino]carbonyl}[1,1′-biphenyl], triethylammonium salt (L2), was prepared and, together with its isomer bearing the polar amido-sulfonate tag in the position 4 of the biphenyl scaffold (compound L1), evaluated as a supporting ligand in Pd-catalyzed cyanation of
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A hydrophilic phosphinobiphenyl amidosulfonate, 2′-(dicyclohexylphosphino)-2- {[(sulfonatomethyl)amino]carbonyl}[1,1′-biphenyl], triethylammonium salt (L2), was prepared and, together with its isomer bearing the polar amido-sulfonate tag in the position 4 of the biphenyl scaffold (compound L1), evaluated as a supporting ligand in Pd-catalyzed cyanation of aryl bromides using K4[Fe(CN)6] as the non-toxic cyanide source. The less sterically demanding ligand L1 was found to form more active catalysts than the newly prepared compound L2. A catalyst formed in situ from palladium(II) acetate and L1 efficiently mediated cyanation of aryl bromides bearing electron-donating substituents but failed in the analogous reactions with electron-poor substrates. Full article
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Open AccessArticle
Preparation of Pd-Diimine@SBA-15 and Its Catalytic Performance for the Suzuki Coupling Reaction
Catalysts 2016, 6(12), 181; doi:10.3390/catal6120181 -
Abstract
A highly efficient and stable Pd-diimine@SBA-15 catalyst was successfully prepared by immobilizing Pd onto diimine-functionalized mesoporous silica SBA-15. With the help of diimine functional groups grafted onto the SBA-15, Pd could be anchored on a support with high dispersion. Pd-diimine@SBA-15 catalyst exhibited excellent
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A highly efficient and stable Pd-diimine@SBA-15 catalyst was successfully prepared by immobilizing Pd onto diimine-functionalized mesoporous silica SBA-15. With the help of diimine functional groups grafted onto the SBA-15, Pd could be anchored on a support with high dispersion. Pd-diimine@SBA-15 catalyst exhibited excellent catalytic performance for the Suzuki coupling reaction of electronically diverse aryl halides and phenylboronic acid under mild conditions with an ultralow amount of Pd (0.05 mol % Pd). When the catalyst amount was increased, it could catalyze the coupling reaction of chlorinated aromatics with phenylboronic acid. Compared with the catalytic performances of Pd/SBA-15 and Pd-diimine@SiO2 catalysts, the Pd-diimine@SBA-15 catalyst exhibited higher hydrothermal stability and could be repeatedly used four times without a significant decrease of its catalytic activity. Full article
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Open AccessArticle
Pulsed Laser Deposition of Platinum Nanoparticles as a Catalyst for High-Performance PEM Fuel Cells
Catalysts 2016, 6(11), 180; doi:10.3390/catal6110180 -
Abstract
The catalyst layers for polymer-electrolyte-membrane (PEM) fuel cells were fabricated by deposition of platinum directly onto the gas diffusion layer using pulsed laser deposition (PLD). This technique reduced the number of steps required to synthesize the catalyst layers and the amount of Pt
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The catalyst layers for polymer-electrolyte-membrane (PEM) fuel cells were fabricated by deposition of platinum directly onto the gas diffusion layer using pulsed laser deposition (PLD). This technique reduced the number of steps required to synthesize the catalyst layers and the amount of Pt loading required. PEM fuel cells with various Pt loadings for the cathode were investigated. With a cathode Pt loading of 100 μg·cm2, the current density of a single cell reached 1205 mA·cm2 at 0.6 V, which was close to that of a single cell using an E-TEK (trademark) Pt/C electrode with a cathode Pt loading of 400 μg·cm2. Furthermore, for a PEM fuel cell with both electrodes prepared by PLD and a total anode and cathode Pt loading of 117 μg·cm2, the overall Pt mass-specific power density at 0.6 V reached 7.43 kW·g1, which was five times that of a fuel cell with E-TEK Pt/C electrodes. The high mass-specific power density was due to that a very thin nanoporous Pt layer was deposited directly onto the gas diffusion layer, which made good contact with the Nafion membrane and thus resulted in a low-resistance membrane electrode assembly. Full article
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