Showing papers on "Benzyl alcohol published in 2018"
TL;DR: In this article, the nitrogen vacancies located at the uncondensed terminal NHx lattice sites were conducive to the enhancement of optical absorption, the improvement of the separation efficiency of the photogenerated charge carrier and the increase of surface area, which was beneficial to the photocatalytic oxidation process.
Abstract: Vacancy defect in the semiconductors plays an important role in the improvement of the electronic structure and the increase of specific reaction sites for reactant molecules, and consequently enhancing the photocatalytic activity of semiconductor photocatalysts. Through high-temperature thermal condensation of a nitric acid-pretreated melamine precursor, nitrogen vacancies were successfully introduced in the framework of g-C3N4. The nitrogen vacancies located at the uncondensed terminal NHx lattice sites were conducive to the enhancement of optical absorption, the improvement of the separation efficiency of the photogenerated charge carrier and the increase of surface area, which was beneficial to the photocatalytic oxidation process. More significantly, the novel CNNA(X) were used as efficient photocatalysts in the green process of aromatic aldehydes from the photocatalytic selective oxidation of aromatic alcohols and the photocatalytic degradation of organic pollutants. CNNA(X) samples exhibited enhanced photocatalytic activity and excellent recyclability and stability. The 68.3% benzyl alcohol conversion and almost 100% selectivity was observed for the CNNA (0.9) photocatalyst, higher than that of pure g-C3N4. Meanwhile, CNNA (0.9) showed superior photocatalytic degradation performance of organic dyes (RhB and MO). Furthermore, the underlying photocatalytic oxidation mechanism was proposed by the controlled experiments using radical scavengers.
239 citations
TL;DR: In this paper, a set of bare and P-doped graphitic carbon nitride (g-C3N4) photocatalysts has been prepared by thermal condensation of melamine, urea or thiourea.
Abstract: A set of bare and P-doped graphitic carbon nitride (g-C3N4) photocatalysts has been prepared by thermal condensation of melamine, urea or thiourea. For the sake of comparison, a g-C3N4 sample obtained in the presence of cyanuric acid and thermally exfoliated C3N4 powders were also studied. The materials were physicochemically characterized and their photocatalytic activity was studied for the selective oxidation of benzyl alcohol (BA), 4-methoxy benzyl alcohol (4-MBA) and piperonyl alcohol (PA) in water suspension both under UV and visible light irradiation. The influence of the type and position of the substituents on conversion and selectivity to aldehyde was remarkable. The presence of P in the C3N4 material improved the selectivity of the reaction towards the aldehyde.
216 citations
TL;DR: In this article, the results indicate that the ratio between manganese and cerium plays a crucial role in the formation of catalysts, and the textual properties as well as catalytic activity are remarked affected.
140 citations
TL;DR: In this article, the adsorptional/photocatalytic activity of nanoparticles, MNCs, and BMNCs were investigated for the removal of fast green (FG) dye from aqueous medium.
138 citations
TL;DR: In this article, a post-grafting strategy via a Schiff base chemical reaction between aldehyde and −NH2 groups within NH2-MIL-125(Ti) has been developed to construct aromatic heterocycle-grafted metal organic frameworks (MOFs) photocatalysts.
Abstract: A novel and facile post-grafting strategy, via a Schiff base chemical reaction between aldehyde and −NH2 groups within NH2-MIL-125(Ti) has been developed to construct aromatic heterocycle-grafted metal organic frameworks (MOFs) photocatalysts. The improved conjugated system in MOFs showed lower band gaps and their excellent catalytic activities were manifested by selective oxidation of alcohols to corresponding aldehydes under visible light irradiation with high conversion and selectivity. Density functional theory (DFT) was applied for simulating the band gaps and electron orbits of heterocycle-grafted MOFs. The post-synthetic aromatic heterocycles in the MOFs network did not influence the original framework, but effectively expanded its π-delocalized system and promoted the separation and transfer of photo-excited charge carriers. As a result, the aromatic heterocycle-grafted MOFs exhibit significantly enhanced visible-light photo-catalytic activity for selective oxidation of alcohols over pristine NH2-MIL-125(Ti). Especially, the NH2-MIL-125(Ti) grafted by 2-quinolinecarboxaldehyde and 3-thiophenecarboxaldehyde showed better performance (more than 85% conversion of benzyl alcohol) due to the excellent photon adsorption and charge carriers transfer of aromatic heterocycles grafted on MOFs. This general grafting strategy can be utilized to graft large numbers of aromatic rings with different molecular structures onto NH2-MIL-125(Ti).
113 citations
TL;DR: Action spectra and electron spin resonance studies reveal that photoexcited electrons formed within CsPbBr3 upon visible-light illumination take part in the reaction via reduction of oxygen to form superoxide radicals, which sheds light on promising new photocatalytic applications of halide perovskites.
Abstract: Halide perovskites have attracted great attention in the fields of photovoltaics, LEDs, lasers, and most recently photocatalysis, owing to their unique optoelectronic properties. The all-inorganic halide perovskite CsPbBr3 /TiO2 composite material catalyzes selective benzyl alcohol oxidation to benzaldehyde under visible-light illumination. The catalyst, which is prepared by a facile wet-impregnation method, shows very good selectivity towards benzaldehyde (>99 % at 50 % conversion). Action spectra and electron spin resonance (ESR) studies reveal that photoexcited electrons formed within CsPbBr3 upon visible-light illumination take part in the reaction via reduction of oxygen to form superoxide radicals. The detailed post-catalysis characterization by UV/Vis and X-ray photoelectron spectroscopy, X-ray diffraction, and high-angle annular dark-field scanning transmission electron microscopy studies further demonstrated the good stability of CsPbBr3 in terms of morphology and crystal structure under the reaction conditions. This study sheds light on promising new photocatalytic applications of halide perovskites.
105 citations
TL;DR: The single-crystalline Ti-carboxylate MOF (DGIST-1) composed of an unprecedented Ti-oxo chain cluster and the porphyrinic ligand, TCPP, exhibited a higher surface area than previously reported Ti-MOFs due to its high crystallinity.
Abstract: Titanium(IV)-based metal-organic frameworks (Ti-MOFs) have received significant attention in recent years due to their numerous photocatalytic applications We herein prepare the single-crystalline Ti-carboxylate MOF (DGIST-1) composed of an unprecedented Ti-oxo chain cluster and the porphyrinic ligand, TCPP (tetrakis(4-carboxyphenyl)porphyrin) Preformed Ti-oxo clusters were used as Ti4+ sources to avoid the spontaneous hydrolysis and condensation reactions of traditional Ti-alkoxide precursors, thus, enabling the formation of the highly crystalline Ti-MOF The successfully activated DGIST-1 exhibited a higher surface area (ie, 19573 m2 g-1 ) than previously reported Ti-MOFs due to its high crystallinity Furthermore, the visible-light-responsive photocatalytic activity of DGIST-1 was confirmed by the simultaneous generation of singlet oxygen (1 O2 ) and superoxide ( O2 - ) species, in addition to the highly efficient and selective oxidation of benzyl alcohol to benzaldehyde
105 citations
TL;DR: In this paper, selective reduction of benzaldehyde to benzyl alcohol (model reaction for low-temperature stabilization of bio-oil) on C-supported Pt, Rh, Pd, and Ni in aqueous phase was conducted using either H2 (thermal catalytic hydrogenation, TCH) or hydrogen generated in situ electrocatalytically (electrocatalytic hydrogenization, ECH).
102 citations
TL;DR: In this paper, a novel flower-like Bi24O31Br10 with surface oxygen vacancies and bromine vacancies was successfully synthesized using a microwave-calcination route.
Abstract: The selective oxidation of benzyl alcohol (BA) into benzaldehyde (BAD) is an attractive model reaction for organic synthesis. Using a microwave-calcination route, a novel flower-like Bi24O31Br10 with surface oxygen vacancies and bromine vacancies was successfully synthesized. In the construction of Bi24O31Br10, glucose acts as a complexing, reducing, and structure-directing agent. The as-synthesized Bi24O31Br10 exhibits excellent activity for the photocatalytic aerobic oxidation of BA into BAD, with >99% conversion and >99% selectivity under blue LED irradiation at ambient conditions, which is 3.3-, 4.7-, and 27.8-fold higher than that of TiO2, Bi4O5Br2, and Bi12O17Cl2, respectively. The high selectivity is due to the suitable energy band of the as-synthesized Bi24O31Br10 (Eg = 2.51 eV, valence band potential = +2.38 V), while the high conversion rate is largely due to the efficient separation of photogenerated carriers, surface defects, positively charge surface, and 3D micro/nano-architecture. The primary active species, including h+, e−, O2−, and OH, are all involved in the photoreaction. On the basis of experimental results and quantum-chemistry calculations, a direct hole oxidative mechanism with two-step dehydrogenation pathway was suggested. In addition, the as-synthesized Bi24O31Br10 catalyst remains stable during the photocatalytic process, indicating its potential for practical applications.
96 citations
TL;DR: Theoretical simulations reveal that the bulkier Pd6 clusters hinder the interactions between hydroxy groups and the CeO2 surface, thus suppressing synergy of Pd-Ce perimeter, indicating that the true active species are single Pd atoms.
Abstract: The active species in supported metal catalysts are elusive to identify, and large quantities of inert species can cause significant waste. Herein, using a stoichiometrically precise synthetic method, we prepare atomically dispersed palladium-cerium oxide (Pd1 /CeO2 ) and hexapalladium cluster-cerium oxide (Pd6 /CeO2 ), as confirmed by spherical-aberration-corrected transmission electron microscopy and X-ray absorption fine structure spectroscopy. For aerobic alcohol oxidation, Pd1 /CeO2 shows extremely high catalytic activity with a TOF of 6739 h-1 and satisfactory selectivity (almost 100 % for benzaldehyde), while Pd6 /CeO2 is inactive, indicating that the true active species are single Pd atoms. Theoretical simulations reveal that the bulkier Pd6 clusters hinder the interactions between hydroxy groups and the CeO2 surface, thus suppressing synergy of Pd-Ce perimeter.
96 citations
TL;DR: In this article, a mixture of bimetallic alloy nanoparticles (NPs) supported on MgAl-LDH (Au-Pd/LDH) was developed as photocatalysts for the selective oxidation of benzyl alcohol to benzaldehyde under visible light irradiation.
TL;DR: In this article, the authors reported a highly efficient catalyst, created by in-situ anchoring cobalt nanoparticles onto cadmium sulfide nanorods, for simultaneous hydrogen evolution and benzaldehyde production from photocatalytic dehydrogenation of benzyl alcohol under visible light.
TL;DR: In this article, a composite Ni-OTiO2 was prepared by doping nickel and introducing excess oxygen defects in TiO2, and the as-synthesized Ni-O2 particles were characterized by scanning electron microscopy.
Abstract: In this study, a novel composite Ni-OTiO2 was prepared by doping nickel and introducing excess oxygen defects in TiO2. The as-synthesized Ni-OTiO2 particles were characterized by scanning electron ...
TL;DR: In this article, a 2D powder-wheels are connected to each other by 5N3IP ligands in infinite 2D sheets in the (001) plane, featuring 1D infinite channels within each layer.
TL;DR: In this article, a cobalt/iron(oxides) heterostructures with interface engineering for regulating surface structure properties toward enhanced oxygen evolution reaction (OER) and benzyl alcohol oxidation (BAO) are demonstrated.
Abstract: Design of advanced electrocatalysts for oxygen evolution reaction (OER) and the alternative reaction is of prime importance to splitting water for hydrogen generation. Herein, cobalt/iron(oxides) heterostructures with interface engineering for regulating surface structure properties toward enhanced OER and benzyl alcohol oxidation (BAO) are demonstrated. Interface engineering triggers generation of local crystallinity and defective oxygen, enabling the material to export 50 mA cm–2 for OER at an overpotential of 329 mV and continuous 20 h of operation without apparent decay. Further, BAO is also boosted on the heterostructures, further propelling water splitting to export 10 mA cm–2 at a voltage of only 1.42 V. Theoretical calculation reveals that the defective sites dominated by interfaces facilitate adsorption/dissociation of intermediates during electrocatalysis. The findings in this work place Fe/Co(oxides) heterostructures as an excellent bifunctional OER/BAO catalyst and also provide a promising int...
TL;DR: Among the above-mentioned photocatalysts, the conversion rate of benzyl alcohol for TiO2@Pt@CeO2 was also the best, and this conclusion was verified by the electron paramagnetic resonance (EPR) spectroscopy.
TL;DR: In this paper, highly selective (97%) benzoin synthesis from benzyl alcohol was achieved over potassium modified g-C3N4 via light-driven tandem selective oxidation and C C coupling.
Abstract: Benzoin is an important feedstock with high additional value for its extensive use in chemical industry. Benzoin condensation characterized by C C coupling between benzaldehyde requires the use of nucleophilic catalysts including cyanide or N-heterocyclic carbene and is restricted to organic medium such as MeCN, diethyl ether, etc. Construction of efficient and non-toxic catalysts for benzoin synthesis still remains a challenge. Herein, highly selective (97%) benzoin synthesis from benzyl alcohol was achieved over potassium modified g-C3N4 via light-driven tandem selective oxidation and C C coupling. The outstanding performance was attributed to alkali modifications on the electronic structure and surface chemical environment of g-C3N4. K+ intercalation not only facilitated the light harvesting as well as the transport of charge carriers, but also induced surface deprotonation of g-C3N4 and thus remarkable nucleophilicity for prompting the C C coupling reactions. This work sheds light on the design of earth-abundant inorganic photocatalysts for C C coupling reactions such as the green synthesis of benzoin under ambient conditions.
TL;DR: CdIn2S4, CdS and In2S3 photocatalysts were fabricated via a facile solvothermal method using indium chloride, cadmium nitrate and thiacetamide as precursors as mentioned in this paper.
TL;DR: The treatment of a benzyl alcohol and aryl halide with a nickel catalyst and low-valent titanium reagent generated from TiCl4(lutidine) and manganese powder afforded the cross-coupled product in high yield.
TL;DR: In this article, nanosized Schiff-base Cu/Ni complexes and their oxides showed remarkable catalytic activity towards the selective oxidation of benzyl alcohol (BzOH) in aqueous H2O2/dimethylsulfoxide (DMSO) solution.
Abstract: In this work, nanosized Cu and Ni Schiff-base complexes, namely ahpvCu, ahpnbCu, and ahpvNi, incorporating imine ligands derived from the condensation of 2-amino-3-hydroxypyridine, with either 3-methoxysalicylaldehyde (ahpv) or 4-nitrobenzaldehyde (ahpnb), were synthesized using sonochemical approach. The structure and properties of the new ligands and their complexes with Ni(II) and Cu(II) were determined via infrared (IR), nuclear magnetic resonance (NMR), electronic spectra (UV-Vis), elemental analysis (CHN), thermal gravimetric analysis (TGA), molar conductivity (Λm), and magnetic moment (μeff). The combined results revealed the formation of 1:1 (metal: ligand) complexes for ahpvCu and ahpvNi and 1:2 for ahpnbCu. Additionally, CuO and NiO nanoparticles were prepared by calcination of the respective nanosized Cu/Ni complexes at 500 °C, and characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Significantly, the as-prepared nanosized Schiff-base Cu/Ni complexes and their oxides showed remarkable catalytic activity towards the selective oxidation of benzyl alcohol (BzOH) in aqueous H2O2/ dimethylsulfoxide (DMSO) solution. Thus, catalytic oxidation of BzOH to benzaldehyde (BzH) using both ahpvCu complex and CuO nanoparticles in H2O2/DMSO media at 70 °C for 2 h yielded 94% and 98% BzH, respectively, with 100% selectivity.
TL;DR: The thermal stability of Co-N-C in reducing environments has been investigated in this article, showing that it can be partially removed by H2 treatments at 523-750 K. In situ characterization of Cu(II) in N-doped carbon revealed that reduction of the metal in H2 started at about 473 K.
Abstract: Atomically dispersed Co(II) cations coordinated to nitrogen in a carbon matrix (Co-N-C) catalyze oxidative dehydrogenation of benzyl alcohol in water with a specific activity approaching that of supported Pt nanoparticles. Whereas Cu(II) cations in N-doped carbon also catalyze the reaction, they are about an order of magnitude less active compared with Co(II) cations. Results from X-ray absorption spectroscopy suggest that oxygen is also bound to N-coordinated Co(II) sites but that it can be partially removed by H2 treatments at 523–750 K. The N-coordinated Co(II) sites remained cationic in H2 up to 750 K, and these stable sites were demonstrated to be active for propane dehydrogenation. In situ characterization of Cu(II) in N-doped carbon revealed that reduction of the metal in H2 started at about 473 K, indicating a much lower thermal stability of Cu(II) in H2 relative to Co(II). The demonstrated high catalytic activity and thermal stability of Co-N-C in reducing environments suggests that this material...
TL;DR: In this paper, the reduction of benzaldehyde to benzyl alcohol on Pd supported on carbon felt was conducted in the aqueous phase using a continuous flow fixed-bed reactor at room temperature and atmospheric pressure.
Abstract: Electrocatalytic reduction of benzaldehyde to benzyl alcohol on Pd supported on carbon felt was conducted in the aqueous phase using a continuous flow fixed-bed reactor at room temperature and atmospheric pressure. Methanol, ethanol, or isopropanol was added to the electrolyte to study the impact of alcohol type and concentration on the rates of benzaldehyde electrocatalytic hydrogenation (ECH) and H2 evolution, which is the prevalent side reaction. Whereas the ECH rates and Faradaic efficiency decreased with increasing alcohol concentrations, H2 evolution rates remained constant. The impact of the alcohol on hydrogenation was greater as the length of the alcohol’s hydrocarbon chain increased. Increasing the benzaldehyde concentration allows for high ECH rates and high Faradaic efficiency. The reaction order increased from ∼0.13 to ∼0.66 with half-cell potential increasing from −650 to −1150 mV (vs Ag/AgCl). Kinetic analysis reveals that the changes in reaction order are due to changes in benzaldehyde (an...
TL;DR: In this paper, a series of catalysts consisting of palladium and gold nanoparticles loaded on carbon (Au-Pd/C) were synthesized and evaluated for the liquid phase oxidation of benzyl alcohol to benzaldehyde.
TL;DR: A concise method to directly generate benzyl radicals from benzyl alcohol derivatives has been developed using a simple and inexpensive combination of TiCl4(collidine) and manganese powder, which facilitated homolytic cleavage of benzylic C-OH bonds.
TL;DR: In this article, a study on the reactivity of polymeric carbon nitride (PCN) and PCN-H2O2 adduct samples for sunlight photocatalytic selective oxidation reactions is presented.
TL;DR: In this paper, a Pt/ZnO catalyst was used for the selective oxidation of benzyl alcohol at room temperature under base-free aqueous conditions, and the resulting solid achieved a high conversion rate (94.1 ± 5.1% in 10 h) of benyl alcohol and nearly 100% selectivity to benzaldehyde with ambient air as the oxidant.
TL;DR: A review of the recent advances on Pd catalyzed benzyl alcohol oxidation can be found in this article, where several catalytic materials obtained by careful control of the morphology of Pd nanoparticles, (including bimetallic systems) and by tuning the support properties have been developed.
Abstract: In the last decades, the selective liquid phase oxidation of alcohols to the corresponding carbonyl compounds has been a subject of growing interest. Research has focused on green methods that use “clean” oxidants such as O2 in combination with supported metal nanoparticles as the catalyst. Among the alcohols, benzyl alcohol is one of the most studied substrates. Indeed, benzyl alcohol can be converted to benzaldehyde, largely for use in the pharmaceutical and agricultural industries. This conversion serves as model reaction in testing new potential catalysts, that can then be applied to other systems. Pd based catalysts have been extensively studied as active catalytic metals for alcohol oxidation for their high activity and selectivity to the corresponding aldehyde. Several catalytic materials obtained by careful control of the morphology of Pd nanoparticles, (including bimetallic systems) and by tuning the support properties have been developed. Moreover, reaction conditions, including solvent, temperature, pressure and alcohol concentration have been investigated to tune the selectivity to the desired products. Different reaction mechanisms and microkinetic models have been proposed. The aim of this review is to provide a critical description of the recent advances on Pd catalyzed benzyl alcohol oxidation.
TL;DR: The first synthetic, functional model of Ln-dependent dehydrogenase and its stoichiometric and catalytic dehydrogenation of a benzyl alcohol is reported, implicating a hydride transfer mechanism for these reactions.
Abstract: The oxidation of methanol by dehydrogenase enzymes is an essential part of the bacterial methane metabolism cycle. The recent discovery of a lanthanide (Ln) cation in the active site of the XoxF dehydrogenase represents the only example of a rare-earth element in a physiological role. Herein, we report the first synthetic, functional model of Ln-dependent dehydrogenase and its stoichiometric and catalytic dehydrogenation of a benzyl alcohol. Density functional theory calculations implicate a hydride transfer mechanism for these reactions.
TL;DR: In this article, a series of CdXZn1−X S (0.78Zn0.22 S) samples were synthesized by a simple wet-chemical method using cadmium nitrate, zinc nitrate and sodium sulfide as precursors, and were thoroughly characterized by many techniques, including X-ray diffraction, UV-vis absorption spectra, nitrogen adsorption-desorption isotherms, scanning electron microscopy, transmission electron microscope and (photo)electrochemical measurements.
TL;DR: In this paper, the performance of different noble metals (NMs) with controllable size (5 nm) as co-catalyst on the photocatalytic oxidation of TiO2@ZnO hollow spheres was tested with benzyl alcohol in the presence of water under ambient conditions.