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Catalysts, Volume 6, Issue 5 (May 2016)

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Research

Jump to: Review

Open AccessArticle Structural and Biochemical Characterization of a Cyanobacterial PP2C Phosphatase Reveals Insights into Catalytic Mechanism and Substrate Recognition
Catalysts 2016, 6(5), 60; doi:10.3390/catal6050060
Received: 26 February 2016 / Revised: 19 April 2016 / Accepted: 20 April 2016 / Published: 26 April 2016
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Abstract
PP2C-type phosphatases play roles in signal transduction pathways related to abiotic stress. The cyanobacterial PP2C-type phosphatase tPphA specifically dephosphorylates the PII protein, which is a key regulator in cyanobacteria adapting to nitrogen-deficient environments. Previous studies have shown that residue His39 of tPphA is
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PP2C-type phosphatases play roles in signal transduction pathways related to abiotic stress. The cyanobacterial PP2C-type phosphatase tPphA specifically dephosphorylates the PII protein, which is a key regulator in cyanobacteria adapting to nitrogen-deficient environments. Previous studies have shown that residue His39 of tPphA is critical for the enzyme’s recognition of the PII protein; however, the manner in which this residue determines tPphA substrate specificity is unknown. Here, we solved the crystal structure of H39A, a tPphA variant. The structure revealed that the mutation of residue His39 to alanine changes the conformation and the flexibility of the loop in which residue His39 is located, and these changes affect the substrate specificity of tPphA. Moreover, previous studies have assumed that the FLAP subdomain and the third metal (M3) of tPphA could mutually influence each other to regulate PP2C catalytic activity and substrate specificity. However, despite the variable conformations adopted by the FLAP subdomain, the position of M3 was consistent in the tPphA structure. These results indicate that the FLAP subdomain does not influence M3 and vice versa. In addition, a small screen of tPphA inhibitors was performed. Sanguinarine and Ni2+ were found to be the most effective inhibitors among the assayed chemicals. Finally, the dimeric form of tPphA was stabilized by cross-linkers and still exhibited catalytic activity towards p-nitrophenyl phosphate. Full article
(This article belongs to the Special Issue Enzyme Catalysis)
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Open AccessArticle The Use of Biobased Surfactant Obtained by Enzymatic Syntheses for Wax Deposition Inhibition and Drag Reduction in Crude Oil Pipelines
Catalysts 2016, 6(5), 61; doi:10.3390/catal6050061
Received: 30 January 2016 / Revised: 6 April 2016 / Accepted: 20 April 2016 / Published: 26 April 2016
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Abstract
Crude oil plays an important role in providing the energy supply of the world, and pipelines have long been recognized as the safest and most efficient means of transporting oil and its products. However, the transportation process also faces the challenges of asphaltene-paraffin
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Crude oil plays an important role in providing the energy supply of the world, and pipelines have long been recognized as the safest and most efficient means of transporting oil and its products. However, the transportation process also faces the challenges of asphaltene-paraffin structural interactions, pipeline pressure losses and energy consumption. In order to determine the role of drag-reducing surfactant additives in the transportation of crude oils, experiments of wax deposition inhibition and drag reduction of different oil in pipelines with a biobased surfactant obtained by enzymatic syntheses were carried out. The results indicated that heavy oil transportation in the pipeline is remarkably enhanced by creating stable oil-in-water (O/W) emulsion with the surfactant additive. The wax appearance temperature (WAT) and pour point were modified, and the formation of a space-filling network of interlocking wax crystals was prevented at low temperature by adding a small concentration of the surfactant additive. A maximum viscosity reduction of 70% and a drag reduction of 40% for light crude oil flows in pipelines were obtained with the surfactant additive at a concentration of 100 mg/L. Furthermore, a successful field application of the drag-reducing surfactant in a light crude oil pipeline in Daqing Oilfield was demonstrated. Hence, the use of biobased surfactant obtained by enzymatic syntheses in oil transportation is a potential method to address the current challenges, which could result in a significant energy savings and a considerable reduction of the operating cost. Full article
(This article belongs to the Special Issue Enzyme Catalysis)
Open AccessArticle Carbon Supported Oxide-Rich Pd-Cu Bimetallic Electrocatalysts for Ethanol Electrooxidation in Alkaline Media Enhanced by Cu/CuOx
Catalysts 2016, 6(5), 62; doi:10.3390/catal6050062
Received: 20 March 2016 / Revised: 13 April 2016 / Accepted: 19 April 2016 / Published: 26 April 2016
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Abstract
Different proportions of oxide-rich PdCu/C nanoparticle catalysts were prepared by the NaBH4 reduction method, and their compositions were tuned by the molar ratios of the metal precursors. Among them, oxide-rich Pd0.9Cu0.1/C (Pd:Cu = 9:1, metal atomic ratio) exhibits
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Different proportions of oxide-rich PdCu/C nanoparticle catalysts were prepared by the NaBH4 reduction method, and their compositions were tuned by the molar ratios of the metal precursors. Among them, oxide-rich Pd0.9Cu0.1/C (Pd:Cu = 9:1, metal atomic ratio) exhibits the highest electrocatalytic activity for ethanol oxidation reaction (EOR) in alkaline media. X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) confirmed the existence of both Cu and CuOx in the as-prepared Pd0.9Cu0.1/C. About 74% of the Cu atoms are in their oxide form (CuO or Cu2O). Besides the synergistic effect of Cu, CuOx existed in the Pd-Cu bimetallic nanoparticles works as a promoter for the EOR. The decreased Pd 3d electron density disclosed by XPS is ascribed to the formation of CuOx and the spill-over of oxygen-containing species from CuOx to Pd. The low Pd 3d electron density will decrease the adsorption of CH3COads intermediates. As a result, the electrocatalytic activity is enhanced. The onset potential of oxide-rich Pd0.9Cu0.1/C is negative shifted 150 mV compared to Pd/C. The oxide-rich Pd0.9Cu0.1/C also exhibited high stability, which indicated that it is a candidate for the anode of direct ethanol fuel cells (DEFCs). Full article
(This article belongs to the Special Issue Carbon Materials for Green Catalysis)
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Open AccessArticle Nickel Catalyzed Conversion of Cyclohexanol into Cyclohexylamine in Water and Low Boiling Point Solvents
Catalysts 2016, 6(5), 63; doi:10.3390/catal6050063
Received: 18 January 2016 / Revised: 30 March 2016 / Accepted: 31 March 2016 / Published: 26 April 2016
Cited by 1 | PDF Full-text (2548 KB) | HTML Full-text | XML Full-text
Abstract
Nickel is found to demonstrate high performance in the amination of cyclohexanol into cyclohexylamine in water and two solvents with low boiling points: tetrahydrofuran and cyclohexane. Three catalysts, Raney Ni, Ni/Al2O3 and Ni/C, were investigated and it is found that
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Nickel is found to demonstrate high performance in the amination of cyclohexanol into cyclohexylamine in water and two solvents with low boiling points: tetrahydrofuran and cyclohexane. Three catalysts, Raney Ni, Ni/Al2O3 and Ni/C, were investigated and it is found that the base, hydrogen, the solvents and the support will affect the activity of the catalyst. In water, all the three catalysts achieved over 85% conversion and 90% cyclohexylamine selectivity in the presence of base and hydrogen at a high temperature. In tetrahydrofuran and cyclohexane, Ni/Al2O3 exhibits better activity than Ni/C under optimal conditions. Ni/C was stable during recycling in aqueous ammonia, while Ni/Al2O3 was not due to the formation of AlO(OH). Full article
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Open AccessArticle Selective Aerobic Oxidation of Benzyl Alcohol Driven by Visible Light on Gold Nanoparticles Supported on Hydrotalcite Modified by Nickel Ion
Catalysts 2016, 6(5), 64; doi:10.3390/catal6050064
Received: 28 November 2015 / Revised: 12 March 2016 / Accepted: 7 April 2016 / Published: 27 April 2016
Cited by 3 | PDF Full-text (1344 KB) | HTML Full-text | XML Full-text
Abstract
A series of hydrotalcite (HT) and hydrotalcite modified by the transition metal ion Ni(II) was prepared with a modified coprecipitation method before being loaded with gold nanoparticles. The gold supported on Ni3Al hydrotalcite with a Ni2+/Al3+ molar ratio
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A series of hydrotalcite (HT) and hydrotalcite modified by the transition metal ion Ni(II) was prepared with a modified coprecipitation method before being loaded with gold nanoparticles. The gold supported on Ni3Al hydrotalcite with a Ni2+/Al3+ molar ratio of 3:1 was investigated. Different techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflection spectrum (UV-vis DRS) were applied to characterize the catalysts. A single-phase catalyst with high crystallinity, a layered structure and good composition was successfully fabricated. Good conversions and superior selectivities in the oxidation of benzyl alcohol and its derivatives were obtained with visible light due to the effect of localized surface plasmon resonance (LSPR) of gold nanoparticles and the synergy of the transition metal ion Ni(II). This reaction was proven to be photocatalytic by varying the intensity and wavelength of the visible light. The catalyst can be recycled three times. A corresponding photocatalytic mechanism of the oxidation reaction of benzyl alcohol was proposed. Full article
(This article belongs to the Special Issue Catalysts for Selective Oxidation)
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Open AccessCommunication Organocatalytic, Asymmetric [2+2+2] Annulation to Construct Six-Membered Spirocyclic Oxindoles with Six Continuous Stereogenic Centers
Catalysts 2016, 6(5), 65; doi:10.3390/catal6050065
Received: 17 March 2016 / Revised: 13 April 2016 / Accepted: 15 April 2016 / Published: 27 April 2016
Cited by 8 | PDF Full-text (1742 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Lactols and cyclic hemiaminals were directly used in a one-pot organo/organo dual catalytic system induced [2+2+2] tandem reaction for the asymmetric construction of six-membered carbocycles. The enamine-based stereoselective Michael addition of lactols or cyclic hemiaminals to electron-deficient olefinic oxindole motifs provided chiral C4
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Lactols and cyclic hemiaminals were directly used in a one-pot organo/organo dual catalytic system induced [2+2+2] tandem reaction for the asymmetric construction of six-membered carbocycles. The enamine-based stereoselective Michael addition of lactols or cyclic hemiaminals to electron-deficient olefinic oxindole motifs provided chiral C4 components, which were further combined with triethylamine catalyzed Michael/Henry sequential reactions affording spirocyclic oxindole derivatives containing six continuous stereogenic centers with excellent enantioselectivities as a single diastereoisomer. All these desired products have versatile molecular complexity, which might have potential applications in synthetic organic chemistry and the pharmaceutical industry. Full article
(This article belongs to the Special Issue Metal-free Organocatalysis)
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Open AccessArticle Immobilization of Genetically-Modified d-Amino Acid Oxidase and Catalase on Carbon Nanotubes to Improve the Catalytic Efficiency
Catalysts 2016, 6(5), 66; doi:10.3390/catal6050066
Received: 24 March 2016 / Revised: 24 April 2016 / Accepted: 28 April 2016 / Published: 9 May 2016
Cited by 1 | PDF Full-text (4963 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
d-amino acid oxidase (DAAO) and catalase (CAT) have been genetically modified by fusing them to an elastin-like polypeptide (ELP). ELP-DAAO and ELP-CAT have been separately immobilized on multi-walled carbon nanotubes (MWNTs). It has been found that the secondary structures of the enzymes
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d-amino acid oxidase (DAAO) and catalase (CAT) have been genetically modified by fusing them to an elastin-like polypeptide (ELP). ELP-DAAO and ELP-CAT have been separately immobilized on multi-walled carbon nanotubes (MWNTs). It has been found that the secondary structures of the enzymes have been preserved. ELP-DAAO catalyzed the oxidative deamination of d-alanine, and H2O2 was evolved continuously. When the MWNT-supported enzymes were used together, the generated hydrogen peroxide of ELP-DAAO could be decomposed in situ. The catalytic efficiency of the two immobilized enzymes was more than five times greater than that of free ELP-DAAO when the ratio of immobilized ELP-CAT to immobilized ELP-DAAO was larger than 1:1. Full article
(This article belongs to the Special Issue Enzyme Catalysis)
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Open AccessArticle Cloning, Expression and Characterization of a Novel Fructosyltransferase from Aspergillus oryzae ZZ-01 for the Synthesis of Sucrose 6-Acetate
Catalysts 2016, 6(5), 67; doi:10.3390/catal6050067
Received: 26 March 2016 / Revised: 18 April 2016 / Accepted: 4 May 2016 / Published: 9 May 2016
Cited by 1 | PDF Full-text (2497 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A 1521 bp gene encoding for a novel fructosyltransferase from Aspergillus oryzae ZZ-01 (AoFT) has been amplified by RACE and TAIL PCR, and functionally overexpressed in Escherichia coli BL 21-CodonPlus (DE3)-RIL. The recombinant A. oryzae ZZ-01 fructosyltransferases (r-AoFT) was
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A 1521 bp gene encoding for a novel fructosyltransferase from Aspergillus oryzae ZZ-01 (AoFT) has been amplified by RACE and TAIL PCR, and functionally overexpressed in Escherichia coli BL 21-CodonPlus (DE3)-RIL. The recombinant A. oryzae ZZ-01 fructosyltransferases (r-AoFT) was purified to homogeneity after Ni-NTA affinity and Superdex-200 gel filtration chromatography. SDS-PAGE analysis of the purified r-AoFT revealed a single protein band with an apparent molecular mass of 60.0 kDa. The r-AoFT enzyme exhibited its optimal activity at 55 °C and pH 5.5, and maintained about 63% of its activity even after 60 min of treatment at 60 °C. The addition of Mg2+ led to an increase in the activity of r-AoFT, whereas Zn2+, Cu2+ and Ni2+ led to a reduction in its activity. Six site-directed mutants of r-AoFT (D39A, D164A, E216A, N38L, S99A and Y282A) were constructed and characterized biochemically. The N38L, S99A and Y282A mutants had lower Km and higher Vmax values than the wild-type enzyme, highlighting their higher binding affinity for the substrates. These results therefore suggest that r-AoFT could be used for the enzymatic synthesis of Suc6A from sucrose and glucose 6-acetate. Full article
(This article belongs to the Special Issue Enzyme Catalysis)
Open AccessArticle CO-Tolerant Pt–BeO as a Novel Anode Electrocatalyst in Proton Exchange Membrane Fuel Cells
Catalysts 2016, 6(5), 68; doi:10.3390/catal6050068
Received: 15 January 2016 / Revised: 12 April 2016 / Accepted: 27 April 2016 / Published: 10 May 2016
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Abstract
Commercialization of proton exchange membrane fuel cells (PEMFCs) requires less expensive catalysts and higher operating voltage. Substantial anodic overvoltage with the usage of reformed hydrogen fuel can be minimized by using CO-tolerant anode catalysts. Carbon-supported Pt–BeO is manufactured so that Pt particles with
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Commercialization of proton exchange membrane fuel cells (PEMFCs) requires less expensive catalysts and higher operating voltage. Substantial anodic overvoltage with the usage of reformed hydrogen fuel can be minimized by using CO-tolerant anode catalysts. Carbon-supported Pt–BeO is manufactured so that Pt particles with an average diameter of 4 nm are distributed on a carbon support. XPS analysis shows that a peak value of the binding energy of Be matches that of BeO, and oxygen is bound with Be or carbon. The hydrogen oxidation current of the Pt–BeO catalyst is slightly higher than that of a Pt catalyst. CO stripping voltammetry shows that CO oxidation current peaks at ~0.85 V at Pt, whereas CO is oxidized around 0.75 V at Pt–BeO, which confirms that the desorption of CO is easier in the presence of BeO. Although the state-of-the-art PtRu anode catalyst is dominant as a CO-tolerant hydrogen oxidation catalyst, this study of Be-based CO-tolerant material can widen the choice of PEMFC anode catalyst. Full article
Open AccessArticle A Novel Delafossite Structured Visible-Light Sensitive AgFeO2 Photocatalyst: Preparation, Photocatalytic Properties, and Reaction Mechanism
Catalysts 2016, 6(5), 69; doi:10.3390/catal6050069
Received: 23 February 2016 / Revised: 29 April 2016 / Accepted: 4 May 2016 / Published: 10 May 2016
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Abstract
This work presents a systematic study of a novel efficient visible-light sensitive AgFeO2 photocatalyst. The photocatalysts were prepared via simple hydrothermal procedure at 160 °C with different reaction time. The structures, morphologies, specific surface areas, and optical properties of the photocatalysts were
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This work presents a systematic study of a novel efficient visible-light sensitive AgFeO2 photocatalyst. The photocatalysts were prepared via simple hydrothermal procedure at 160 °C with different reaction time. The structures, morphologies, specific surface areas, and optical properties of the photocatalysts were explored by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) model, and UV-vis diffuse reflectance spectra (DRS). Photoluminescence and photocurrent analysis were conducted for the understanding of photogenerated electron-hole pair separation. AgFeO2 with a six-hour hydrothermal procedure demonstrated the most efficient photocatalytic performance which resulted in 97% degradation of methyl orange (MO) within 180 min. The enhanced photocatalytic activity was attributed to the combined effect of its relatively large surface area and high separation electron-hole pair efficiency. Holes and ·O2 were the dominant reactive species responsible for MO degradation and holes played the leading role according to the quenching effects analysis and detection of active species. The conduction and valence band position of AgFeO2 were calculated to be −0.5 V and 1.32 V, respectively. Based on active species detection, along with the band structure, the photocatalytic mechanism was proposed. Full article
(This article belongs to the Special Issue Photocatalytic Wastewater Treatment)
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Open AccessArticle Rare Earth-Promoted Nickel Oxide Nanoparticles as Catalysts for N2O Direct Decomposition
Catalysts 2016, 6(5), 70; doi:10.3390/catal6050070
Received: 31 March 2016 / Revised: 30 April 2016 / Accepted: 9 May 2016 / Published: 17 May 2016
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Abstract
For this paper, a series of rare earth (Gd, La, Sm) promoted NiO catalysts were prepared by using the microwave-assisted precipitation method and tested for N2O direct decomposition. The obtained solids have been characterized by using various techniques. X-ray diffraction (XRD)
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For this paper, a series of rare earth (Gd, La, Sm) promoted NiO catalysts were prepared by using the microwave-assisted precipitation method and tested for N2O direct decomposition. The obtained solids have been characterized by using various techniques. X-ray diffraction (XRD) results revealed that the incorporation of RE oxides into NiO significantly decreases its crystallite size. Field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations indicated that the addition of RE oxides swells the NiO particles yielding particles into a rice-like morphology. N2 adsorption studies showed a sharp surface area increase as well as mesoporosity development accompanied the RE incorporation. It was found that the RE oxides significantly enhance the NiO activity. Full article
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Open AccessArticle The Simple, Effective Synthesis of Highly Dispersed Pd/C and CoPd/C Heterogeneous Catalysts via Charge-Enhanced Dry Impregnation
Catalysts 2016, 6(5), 72; doi:10.3390/catal6050072
Received: 14 March 2016 / Revised: 25 April 2016 / Accepted: 4 May 2016 / Published: 16 May 2016
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Abstract
Pd/C and CoPd/C heterogeneous catalysts have been synthesized by adopting Charge Enhanced Dry Impregnation (CEDI). The particles size distribution, their high metal surface-to-bulk ratios, and synthesis feasibility are unmatchable to any known noble metal bimetallic heterogeneous catalyst preparation techniques. Next generation Fuel Cells
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Pd/C and CoPd/C heterogeneous catalysts have been synthesized by adopting Charge Enhanced Dry Impregnation (CEDI). The particles size distribution, their high metal surface-to-bulk ratios, and synthesis feasibility are unmatchable to any known noble metal bimetallic heterogeneous catalyst preparation techniques. Next generation Fuel Cells and Fischer-Tropsch catalytic processes economy will be benefited from the proposed methodology. Full article
(This article belongs to the Special Issue Rational Synthesis of Supported Bimetallic Catalysts)
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Open AccessArticle Adsorption and Oxidation Investigations over Pt/Al2O3 Catalyst: A Microcalorimetric Study
Catalysts 2016, 6(5), 73; doi:10.3390/catal6050073
Received: 11 February 2016 / Revised: 27 April 2016 / Accepted: 5 May 2016 / Published: 17 May 2016
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Abstract
The differential adsorption heats of oxygen and NO, as well as catalytic oxidation behavior during NO oxidation and NO2 dissociation reactions over supported Pt-catalysts, were investigated by microcalorimetric measurements. The average heat of adsorption (∆H) of oxygen ranged from 310 kJ/mol at
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The differential adsorption heats of oxygen and NO, as well as catalytic oxidation behavior during NO oxidation and NO2 dissociation reactions over supported Pt-catalysts, were investigated by microcalorimetric measurements. The average heat of adsorption (∆H) of oxygen ranged from 310 kJ/mol at 200 °C to 289 kJ/mol at 400 °C. Over this temperature range formation of platinum oxides and coverage dependence caused variations in the apparent heat of adsorption. NO heat of adsorption from 50 to 150 °C was near constant with an average value of 202 kJ/mol over the temperature range. Full article
(This article belongs to the Special Issue Automotive Emission Control Catalysts)
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Open AccessArticle Facile Synthesis of Vanadium Oxide/Reduced Graphene Oxide Composite Catalysts for Enhanced Hydroxylation of Benzene to Phenol
Catalysts 2016, 6(5), 74; doi:10.3390/catal6050074
Received: 4 March 2016 / Revised: 5 May 2016 / Accepted: 10 May 2016 / Published: 17 May 2016
Cited by 4 | PDF Full-text (2364 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The vanadium oxide/reduced graphene oxide (VOx/RGO) composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VO
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The vanadium oxide/reduced graphene oxide (VOx/RGO) composites have been prepared by a simple solvothermal method with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The microstructure and morphology of the resultant VOx/RGO composites have been well characterized. The VOx nanoparticles are highly dispersed on the RGO sheets with a particle size of about 25 nm. When used as hydroxylation catalysts, the VOx/RGO composites are more efficient than individual RGO and vanadium oxide catalysts. The enhanced catalytic performance may be related to not only the well dispersed VOx active species, but also the hydrophobic surface and huge π-electron system of RGO for the adsorption and activation of benzene. In addition, the effects of calcination conditions on the microstructure and catalytic properties of VOx/RGO composites have also been investigated. The uniform VOx nanoparticles on the separated RGO sheets show highly efficient catalytic performance, while the formation of aggregated HxV2O5 and bulk V2O5 species along with the destruction of RGO sheets are poor for the hydroxylation of benzene. Up to 17.4% yield of phenol is achieved under the optimized catalytic reaction conditions. Full article
(This article belongs to the Special Issue Carbon Materials for Green Catalysis)
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Open AccessArticle Cu-Mo2C/MCM-41: An Efficient Catalyst for the Selective Synthesis of Methanol from CO2
Catalysts 2016, 6(5), 75; doi:10.3390/catal6050075
Received: 26 April 2016 / Revised: 12 May 2016 / Accepted: 16 May 2016 / Published: 20 May 2016
Cited by 6 | PDF Full-text (2659 KB) | HTML Full-text | XML Full-text
Abstract
Supported molybdenum carbide (yMo2C/M41) and Cu-promoted molybdenum carbide, using a mechanical mixing and co-impregnation method (xCuyMo2C/M41-M and xCuyMo2C/M41-I) on a mesoporous molecular sieve MCM-41, were
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Supported molybdenum carbide (yMo2C/M41) and Cu-promoted molybdenum carbide, using a mechanical mixing and co-impregnation method (xCuyMo2C/M41-M and xCuyMo2C/M41-I) on a mesoporous molecular sieve MCM-41, were prepared by temperature-programmed carburization method in a CO/H2 atmosphere at 1073 K, and their catalytic performances were tested for CO2 hydrogenation to form methanol. Both catalysts, which were promoted by Cu, exhibited higher catalytic activity. In comparison to 20Cu20Mo2C/M41-M, the 20Cu20Mo2C/M41-I catalyst exhibited a stronger synergistic effect between Cu and Mo2C on the catalyst surface, which resulted in a higher selectivity for methanol in the CO2 hydrogenation reaction. Under the optimal reaction conditions, the highest selectivity (63%) for methanol was obtained at a CO2 conversion of 8.8% over the 20Cu20Mo2C/M41-I catalyst. Full article
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Review

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Open AccessReview An Overview of Recent Advances of the Catalytic Selective Oxidation of Ethane to Oxygenates
Catalysts 2016, 6(5), 71; doi:10.3390/catal6050071
Received: 6 April 2016 / Revised: 6 May 2016 / Accepted: 10 May 2016 / Published: 16 May 2016
Cited by 3 | PDF Full-text (2566 KB) | HTML Full-text | XML Full-text
Abstract
The selective partial oxidation of short chain alkanes is a key challenge within catalysis research. Direct ethane oxidation to oxygenates is a difficult aim, but potentially rewarding, and it could lead to a paradigm shift in the supply chain of several bulk chemicals.
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The selective partial oxidation of short chain alkanes is a key challenge within catalysis research. Direct ethane oxidation to oxygenates is a difficult aim, but potentially rewarding, and it could lead to a paradigm shift in the supply chain of several bulk chemicals. Unfortunately, low C–H bond reactivity and kinetically labile products are just some reasons affecting the development and commercialisation of such processes. Research into direct ethane oxidation is therefore disparate, with approaches ranging from oxidation in the gas phase at high temperatures to enzyme catalysed hydroxylation under ambient conditions. Furthermore, in overcoming the barrier posed by the chemically inert C–H bond a range of oxidants have been utilised. Despite years of research, this remains an intriguing topic from both academic and commercial perspectives. Herein we describe some recent developments within the field of catalytic ethane oxidation focusing on the formation of oxygenated products, whilst addressing the key challenges which are still to be overcome. Full article
(This article belongs to the Special Issue Catalysts for Selective Oxidation)
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