Production Of Benzaldehyde Research Articles

Enhanced Boron Modified Graphitic Carbon Nitride for the Selective Photocatalytic Production of Benzaldehyde

Enhanced Boron Modified Graphitic Carbon Nitride for the Selective Photocatalytic Production of Benzaldehyde

Amorphous nickel borate as a high-efficiency cocatalyst for H2 generation and fine chemical synthesis

The exploration of active and low-cost cocatalyst is one of the most important topics in photocatalysis. Amorphous transition metal borates are a kind of promising cocatalyst with abundant unsaturated sites and high electrical conductivity. However, the relevant research is scanty. Here, we report the growth of Ni-Bi cocatalyst onto ZnIn2S4 nanosheets, for simultaneous H2 evolution and benzaldehyde production. The ZnIn2S4 nanosheet with a suitable band gap acts as an ideal photoactive substrate, while the Ni-Bi cocatalyst provides plentiful active sites and accelerates surface reactions. This study may enlighten the design of high-efficiency transition metal borates cocatalysts for photocatalytic application.

Atomic-level insight into effect of substrate concentration and relative humidity on photocatalytic degradation mechanism of gaseous styrene

Substrate concentration and relative humidity (RH) impact the photocatalytic efficiency of industrial aromatic hydrocarbons, but how they influence intermediate formation and degradation pathway remains unclear. With the help of oxygen isotope tracing method, the effects of these two environmental parameters on degradation mechanism of styrene were revealed at atomic level. Increasing styrene concentration favored product formation, which was however inhibited by RH elevation. Gaseous products were not directly formed in gaseous phase, but originated from desorption of interfacial intermediates. The volatile aldehydes and furans further exchanged their 16O with 18O in H218O. Increase of RH showed higher enhancement on 18O distribution in all products and pathways than that of substrate concentration. Low RH preferred high generation of 16O2•- and (16)1O2, dominating reaction to form 1-phenyl-1,2-ethandiol, 2-hydroxy-1-phenyl-ethanon and phenylglyoxal monohydrate in sequence. Successive production of benzyl alcohol, benzaldehyde and benzoic acid through the reaction of styrene with promoted •18OH by increasing RH became predominant. Hydration was firstly observed and confirmed as an important gaseous transformation step of aldehyde and furan products. Our findings provide a deep insight into photocatalytic degradation mechanism of aromatic hydrocarbons regulated by environmental parameters to further improve their industrial purification efficiency, and are helpful predicting environmental geochemistry fate of organics and preventing their negative impact on natural environment.

Identification of active sites of B/N co-doped nanocarbons in selective oxidation of benzyl alcohol

Developing highly active and stable nanocarbon catalysts for selective oxidation reactions has attracted much attention due to their potential as an alternative to traditional metal-based or noble metal catalysts. However, the nature of active sites and the reaction mechanism of nanocarbon catalysts for oxidation reactions still remains largely unknown, which hinders the rational design and development of highly efficient carbon-based catalysts. Here we report a facile strategy for the synthesis of boron and nitrogen co-doped carbon nanosheet material (BNC), which exhibits excellent catalytic activity with 91% conversion and 99% selectivity in selective oxidation of benzyl alcohol into benzaldehyde, superior to those of traditional carbon materials (oxidized carbon nanotubes, graphites and commercial nanocarbons). Structural characterizations and kinetic measurements are studied to clarify the active site, in which phenolic hydroxyl on BNC is responsible for the production of benzaldehyde. Meanwhile, we put forward a possible reaction mechanism and point out the key factors in determining the reactivity for this reaction. Therefore, the present work provides new insight into structure–function relationships, paving the way for the development of highly efficient nanocarbon catalysts.

Activating Carbon Nitride by BP@Ni for the Enhanced Photocatalytic Hydrogen Evolution and Selective Benzyl Alcohol Oxidation.

Two-dimensional (2D) semiconductors are promising photocatalysts; in order to overcome the relatively low efficiency of single-component 2D photocatalysts, heterostructures are fabricated for effective charge separation. Herein, a 2D heterostructure is synthesized by anchoring nickel nanoparticle-decorated black phosphorus (BP) nanosheets to graphitic carbon nitride (CN) nanosheets (CN/BP@Ni). The CN/BP@Ni heterostructure exhibits an enhanced charge separation due to the tight interfacial interaction and the cascaded electron-transfer channel from CN to BP and then to Ni nanoparticles. Possessing abundant active sites of Ni and P-N coordinate bonds, CN/BP@Ni shows a high visible-light-driven H2 evolution rate of 8.59 mmol·h-1·g-1 with the sacrificial agent EtOH, about 10-fold to that of CN/BP. When applying benzyl alcohol to consume photogenerated holes, CN/BP@Ni enables the selective production of benzaldehyde; therefore, two value-added products are obtained in a single closed redox cycle. This work provides new insights into the development of photocatalysts without non-noble metals.

Synergistic effect of oxygen defect and doping engineering on S-scheme O-ZnIn2S4/TiO2-x heterojunction for effective photocatalytic hydrogen production by water reduction coupled with oxidative dehydrogenation

Aiming to the unwanted photocatalytic hydrogen production systems using sacrifice agents, a well-design S-scheme O-ZnIn2S4/TiO2-x heterojunction was fabricated to realize photocatalytic hydrogen production via water reduction coupled with organic oxidative dehydrogenation. As supported by DFT calculations and experimental analysis, owing to the synergistic effect of oxygen defect and doping engineering, a tailored energy band structure alignment with higher redox potentials and larger Fermi level potential difference are achieved, resulting in more efficient S-scheme interface charge transfer and separation efficiency, thus improving the photocatalytic activity of O-ZnIn2S4/TiO2-x. The optimal O-ZnIn2S4/TiO2-x photocatalyst shows remarkable H2 and benzaldehyde production rate of 2584.9 μmol g-1h−1 and 2880.5 μmol g-1h−1 under visible light, which are 52.5 and 66.4 times as high as those over blank TiO2. Interestingly, this coupled reaction system also displays superior H2 evolution activity compared to sacrificial reagent systems of Na2SO3/Na2S and triethanolamine. Further quenching and EPR experiments reveal that both water and organic molecules provide protons for H2 production.

Cooperative hydrogen production and C−C coupling organic synthesis in one photoredox cycle

Coupling hydrogen fuel production with selective oxidative organic synthesis in one cooperative manner offers a promising avenue to enable efficient utilization of photoexcited carriers to achieve sustainable chemistry. Herein, a new Mo2N/Mn0.3Cd0.7S/CoPi photocatalyst is reported for visible-light-driven hydrogen production paired with selectively oxidative CC bond formation. Mo2N acting as electron collectors and reduction sites are adsorbed on the Mn0.3Cd0.7S by interfacial Mo-S bond, while CoPi acting as hole collectors and active sites for oxidation reaction are deposited on Mo2N/Mn0.3Cd0.7S. Remarkably, the synergetic effect of Mo2N and CoPi dual cocatalysts results in the adjustable flexibility of switching benzaldehyde (BAD) production to CC coupling synthesis, thus exhibiting the high selectivity of CC coupling products. Mechanism studies indicate that the CC coupling reaction occurs through a free radical mechanism. The present work gives insight for achieving highly efficient C−C coupling synthesis with hydrogen evolution by loading dual cocatalysts.

Selective photocatalytic synthesis of benzaldehyde in microcapillaries with immobilized carbon nitride

Photocatalysis on microfluidic reactors can be an environmental-friendly strategy to conventional chemical synthesis methods to find selective and efficient processes to produce high value-added molecules.In this work, we report for the first time a fluoropolymer microcapillary system with an immobilizedmetal-free thermal modified carbon nitride (GCN-T)catalyst. This strategy enabled a user-friendly, plug-and-plug selective chemistry using an external UV light (λ = 392 nm) and aqueous solutions. To intensify the Benzaldehyde (BAL) production, we explored the microfluidic photocatalytic conversion of Benzyl alcohol (BA). We obtained 0.20 mM of BAL using immobilized GCN-T after 2.4 min of residence time. The results were benchmarked against the same reactor using suspended catalysts and against a conventional batch reactor. Immobilized GCN performed similarly to suspended GCN in the microfluidic reactor (0.18 mM of BAL). We increase BAL yield by 9-fold after 2.4 min using suspended GCN in a microfluidic reactor comparing to a batch reactor. The stability of immobilized photocatalyst was confirmed in reuse studies where 0.20 and 0.17 mM of BAL were produced after one and four utilization runs, respectively. We anticipate this can be related to the presence of a high concentration of particles closer to the microreactor’s inner wall, allowing the effective activation of GCN particles with UV irradiation. The immobilization of the catalyst avoided its blockage in the microfluidic channels and enabled the reuse without any further separation. To the best of our knowledge, this is the first report using the microcapillary film reactor and immobilized carbon nitride for the selective photocatalytic synthesis of BAL.

Benzyl alcohol to benzaldehyde oxidation on MnOx clusters: Unraveling atomistic features

• Catalytic oxidation of benzyl alcohol to benzaldehyde over MnO x catalysts is analyzed in the DFT framework. • Oxidation reactivity and selectivity over cluster-sized Mn 4 O 8 and Mn 4 O 9 catalytic models is compared. • Catalyst poisoning is addressed by investigating the formation of benzoic acid following that of benzaldehyde. • Reaction steps and the related oxidation pathways are collected and analyzed by an original kinetic approach. • Experimental strategies aimed at decreasing catalyst deactivation hence at increasing selectivity are proposed. The catalytic oxidation of benzyl alcohol with O 2 is a promising option for the production of benzaldehyde, from both environmental and economical viewpoints. In particular, highly dispersed MnO x systems feature good activity and selectivity in a wide range of temperatures, although deactivation phenomena by over-oxidation and/or poisoning of active sites are generally recorded. On this account, a density functional theory study was performed on cluster-sized catalyst models, namely Mn 4 O 8 and over-oxygenated Mn 4 O 9 fragments, to predict the reactivity pattern of MnO x catalysts in the selective aerobic oxidation of benzyl alcohol. Several pathways concur to determine the whole reaction process and all of them were compared to unveil the atomistic details of the alcohol oxidation mechanism. Moreover, assuming that the consecutive formation of benzoic acid affects the activity-stability pattern of the MnO x based catalyst, also the benzaldehyde oxidation mechanism was computationally addressed. A systematic comparison of the benzyl alcohol and benzaldehyde oxidation mechanisms on the Mn 4 O 8 and Mn 4 O 9 fragments reveals some experimental strategies to test the reaction mechanisms and design alternative catalytic routes to decrease undesired parasitic reactions leading to catalyst deactivation. The matching structural, energetic and kinetic data are published in the Data in Brief journal [1].

Anions‐Exchange‐Induced Efficient Carrier Transport at CsPbBrxCl3‐x/TiO2 Interface for Photocatalytic Activation of C(sp3)−H bond in Toluene Oxidation

AbstractInspired by the unique band structure of CsPbBr3, we have developed an asymmetric Cl‐exchange strategy based on the CsPbBrxCl3‐x/TiO2 heterojunction‐type catalyst and achieved photocatalytic activation of C(sp3)−H bond using the toluene oxidation reaction as a proof‐of‐concept application. The anion exchange at the supported CsPbBr3 surface results in the CsPbBrxCl3‐x/TiO2 structure with an asymmetric distribution of halide. The resultant heterojunction‐type catalysts exhibit significantly improved photocatalytic activity for toluene oxidation reaction with the highest benzaldehyde production rate at 1874 μmol g−1 h−1 (∼4 times that of the naked CsPbBr3 nanocrystals). The remarkable photocatalytic performance can be ascribed to the improved carrier transport at CsPbBrxCl3‐x/TiO2 interface enabled by the unique band structure due to the asymmetric halide distribution, verified by the micro‐strain discovered through the X‐ray diffraction. This work demonstrates a new pathway to fabricate highly‐efficient halide perovskite heterojunction‐type catalysts for photocatalytic activation of C(sp3)−H bond.

Selective Styrene Oxidation to Benzaldehyde over Recently Developed Heterogeneous Catalysts.

The selective oxidation of styrene under heterogeneous catalyzed conditions delivers environmentally friendly paths for the production of benzaldehyde, an important intermediate for the synthesis of several products. The present review explores heterogeneous catalysts for styrene oxidation using a variety of metal catalysts over the last decade. The use of several classes of supports is discussed, including metal–organic frameworks, zeolites, carbon materials and silicas, among others. The studied catalytic systems propose as most used oxidants tert-butyl hydroperoxide, and hydrogen peroxide and mild reaction conditions. The reaction mechanism proceeds through the generation of an intermediate reactive metal–oxygen species by catalyst-oxidant interactions. Overall, most of the studies highlight the synergetic effects among the metal and support for the activity and selectivity enhancement.

Distribution Changes during Thermal Degradation of Poly(styrene peroxide) by Pairing Tree-Based Kinetic Monte Carlo and Artificial Intelligence Tools

A tree-based kinetic Monte Carlo (kMC) model is presented that differentiates between 38 end-group pairs for isothermal degradation of poly(styrene peroxide) (PSP). The binary trees allow for fast and accurate calculation of reaction probabilities, with mass-weighted binary trees for the accurate sampling of peroxide bond fissions and hydrogen abstractions along chains. The kinetic parameters are tuned via artificial neural networks (ANNs) to successfully predict literature experimental data, among other lumped product yields. ANNs are also utilized for sensitivity analysis to unravel the effects of individual reactions on the time evolution of experimental responses and other simulation outputs, including the variations of the chain length distributions of the macrospecies. PSP degradation is characterized by three stages of degradation considering both instantaneous and time-averaged concentrations. The first stage features rapid unzipping and results in the fast production of major products benzaldehyde and formaldehyde, the second stage features the most significant level of hydrogen abstractions involving PSP and other macrospecies types, and the third stage exhibits the consumption of the remaining peroxide bonds toward oligomeric species in a wide time frame until the degradation process is finalized by the depletion of peroxide bonds. This proof-of-concept study based on unprecedentedly detailed analyses of the chemistry via kinetic Monte Carlo paves the way to further improve our understanding of chemical recycling of solid plastic waste.

Volatile compounds in Chinese steamed bread influenced by fermentation time, yeast level and steaming time

The aim of this work is to investigate how volatile compounds of Chinese steamed bread (CSB) are influenced by yeast level (0.5, 1 and 1.5%, flour weight basis), fermentation time (20, 40 and 60 min) and steaming time (5, 10, 20 and 30 min). The volatile compounds were extracted by headspace-solid phase microextraction and analyzed by gas chromatography-mass spectrometry. Higher yeast level and longer fermentation time promoted the formation of yeast-metabolism-derived compounds, including 2-methyl-1-propanol, 3-methyl-1-butanol, phenethyl acetate, hexyl acetate and 2-octanone. Increased fermentation time decelerated the generation of lipid oxidation compounds (octanal, nonanal, decanal, (E)-2-nonenal, and (E,E)-2,4-decadienal). Prolonged steaming time facilitated the production of benzaldehyde and 2-pentylfuran and promoted the loss of alcohols and esters. Network analysis showed that 2-pentylfuran contributed to wheat-like aroma of CSB while 3-methyl-1-butanol was related with alcoholic odor. This study was helpful for improving the understanding of CSB aroma evolution profile and may contribute to the aroma improvement of commercial CSB.

Heteropolyacids-Immobilized Graphitic Carbon Nitride: Highly Efficient Photo-Oxidation of Benzyl Alcohol in the Aqueous Phase

Abstract Benzaldehyde is a highly desirable chemical due to its extensive application in medicine, chemical synthesis and food sector among others. However, its production generally involves hazardous solvents such as trifluorotoluene or acetonitrile, and its conversion, especially selectivity in the aqueous phase, is still not up to expectations. Hence, developing an environmentally benign, synthetic process for benzaldehyde production is of paramount importance. Herein, we report the preparation of a photocatalyst (PW12-P-UCNS, where PW12 is H3PW12O40·xH2O and P-UCNS is phosphoric acid-modified unstack graphitic carbon nitride) by incorporating phosphotungstic acid on phosphoric acid-functionalised graphitic carbon nitride (g-C3N4) nanosheets. The performance of PW12-P-UCNS was tested using the benzyl alcohol photo-oxidation reaction to produce benzaldehyde in H2O, at room temperature (20 °C). The as-prepared PW12-P-UCNS photocatalyst showed excellent photocatalytic performance with 58.3% conversion and 99.5% selectivity within 2 h. Moreover, the catalyst could be reused for at least five times without significant activity loss. Most importantly, a proposed Z-scheme mechanism of the PW12-P-UCNS-catalysed model reaction was revealed. We carefully investigated its transient photocurrent and electrochemical impedance, and identified superoxide radicals and photogenerated holes as the main active species through electron spin-resonance spectroscopy and scavenger experiments. Results show that the designed PW12-P-UCNS photocatalyst is a highly promising candidate for benzaldehyde production through the photo-oxidation reaction in aqueous phase, under mild conditions.

Novel approach to synthesise MoO3-TiO2 nanocomposites for the photo-assisted oxidation of benzyl alcohol to benzaldehyde

Nowadays, there is a significant interest in the development of environment friendly catalysts for alcohols oxidation. Aiming to produce improved catalytic materials, here, the synthesis of new TiO2-MoO3 nanocomposites, using distinct approaches is described. The samples were obtained by hydrothermal treatment of a molybdenum oxide precursor in the presence of TiO2 using a step-by-step procedure (sample TM3) or using a one-pot approach (sample PTM3). Depending on the synthesis route, distinct morphologies, surface area and optical properties for the prepared samples, were obtained. The photocatalytic activity of the nanocomposite samples was evaluated for benzyl alcohol oxidation, under visible and UV-visible radiation. The results indicate that both materials are catalytic, presenting high selectivity for benzaldehyde production. Using UV–vis radiation, the best photocatalyst was PTM3 with 98% selectivity and under visible irradiation was TM3 with 99% of selectivity, with this performance being better than the one presented by either TiO2 or MoO3 separately.

Novel Pd-loaded urchin-like (NH4)xWO3/WO3 as an efficient visible-light-driven photocatalyst for partial conversion of benzyl alcohol

Photocatalytic oxidation of organic compounds by solar light is a promising strategy for environmentally benign conversion processes. Herein, we first report an urchin-like Pd/(NH4)xWO3/WO3 with three-dimensional hierarchical microstructure prepared through a thiourea-assisted solvothermal method followed by calcination under the reductive atmosphere. The Pd/(NH4)xWO3/WO3 exhibits higher selectivity in comparison to Pd/WO3 nanorods in the partial conversion of aqueous benzyl alcohol into benzaldehyde (e.g., 80% selectivity for benzaldehyde production with ca. 84% conversion of benzyl alcohol) under visible light irradiation. The preferential generation of hydroxyl radicals from water on the (NH4)xWO3/WO3 surface in the initial reaction stage was responsible for the high selectivity for benzaldehyde production because hydroxyl radicals react with benzyl alcohol much more efficiently than benzaldehyde. DFT calculations demonstrate that the energy barrier of the reaction between benzyl alcohol and hydroxyl radicals largely decreased due to the photo-excited triplet states of (NH4)xWO3/WO3, while such a trend in the energy barrier was not observed for other photocatalysts. On the other hand, with extended irradiation time, a large amount of hydrogen peroxide, which was produced by the multi-electron reduction of oxygen molecules, accumulates on the Pd/(NH4)xWO3/WO3 due to the low activity of the Pd cocatalyst. The generated hydrogen peroxide preferentially eliminated the photoexcited holes when the concentrations of benzaldehyde increased, thus inhibiting the peroxidation of benzaldehyde by holes. The Pd/(NH4)xWO3/WO3 may provide a feasible strategy for the photocatalytic oxidation of various other organic compounds due to its unique reactivity shown in this study.

Investigations of supported Au-Pd nanoparticles on synthesized CeO2 with different morphologies and application in solvent-free benzyl alcohol oxidation

Au-Pd bimetallic nanoparticles immobilized on series of CeO2 supports with different morphologies, e.g., rod, cube, and polyhedrons were prepared through the deposition-precipitation method with a consequent investigation on their catalytic performances for benzyl alcohol oxidation in the absence of solvent. The experimental results exhibited that the morphology of CeO2 has a markedly impact on the catalytic performance of Au-Pd/CeO2. In which Au-Pd supported on CeO2 rod could achieve higher benzyl alcohol conversion than that supported on CeO2 polyhedrons and CeO2 cube, however, CeO2 cube supported Au-Pd showed the highest selectivity towards the production of benzaldehyde. ICP-AES, XRD, Raman, N2-BET, TEM, HAADF-STEM, and XPS were conducted to characterize the catalysts. The results revealed that the excellent behavior of Au-Pd/CeO2-rod in benzyl alcohol oxidation was closely related with the smaller size of CeO2 particle, the higher concentration of oxygen defects in support and the higher number of Ce3+ and Pd2+ species on the catalyst surface. The present study on the morphologies of CeO2 support in solvent-free benzyl alcohol oxidation would offer a notable approach for the future catalyst design.

Synthesis of nanorod MOF catalyst containing Cu2+ and its selective oxidation of styrene

Different from the traditional aldimine condensation reaction, N-containing ligand: pyridine-2-formaldehyde was selected as the source of aldehyde group, and NH2-MIL-53(Al) containing a large number of amino functional groups was took as the carrier, transition metal Cu2+ coordinated with N-containing ligand to prepare a new and more stable MOFs catalyst named Cu@Al-MIL-53-P21. The catalyst exhibited a cross-linked nanorod morphology. The effect of the morphology on the catalytic oxidation activity of styrene was studied, the results showed that the catalyst could not only promote the production of benzaldehyde, but also inhibit the production of benzoic acid and phenylacetaldehyde. In addition, the optimal reaction conditions and the reaction mechanism were also discussed in this paper.

Synthesis, catalysis, antimicrobial activity, and DNA interactions of new Cu(II)-Schiff base complexes

Structural features and catalytic activities of five ternary copper (II)-Schiff base complexes are investigated. The ligands are derived from 3-methoxysalicylaldehyde (MS) or 4-diethylaminosalicylaldehyde (DS) and amino acids {L-phenylalanine (Phe), L histidine (His) or DL-tryptophan (Trp)}, as primary ligands, and 2,4′-bipyridyl (DP) as a secondary ligand. Cu(II)-complexes are characterized by various physicochemical tools. The catalytic efficiency of Cu(II)-complexes is studied in the oxidation of benzyl alcohol by an aqueous H2O2 in different reaction conditions. Temperature and catalyst features are involved in order to obtain the optimized catalytic oxidation conditions of benzaldehyde production. The Schiff base ligands and their ternary complexes are screened for their antimicrobial activities in various types of fungi and bacteria. The interaction between Cu(II)-complexes and (CT-DNA) was examined by employing various techniques, including viscosity, spectral and gel electrophoreses studies.

Cu(II) ions loaded on magnesium silicate nanofibers for the liquid oxidation of benzyl alcohol

Cu(II) ions were precipitated on nanofiberous magnesium silicate support using hydroxide solution. The texture and characterization of the obtained solids have been investigated by physical methods including XRD, SEM, BET, EDS, XPS, and FT-IR. The catalysts showed medium surface area, highly distributed Cu(II) oxide on the sepiolite fibers. In the liquid-phase oxidation of benzyl alcohol at low temperatures, CuO serves as an active component for the selective production of benzaldehyde. The catalytic activity of the prepared CuO/sepiolite was associated with the dispersion and amount of CuO loading, location and oxidation states of active sites, preparation routes, and reaction variables. Cu2+/sepiolite is active for the selective oxidation of benzyl alcohol to benzaldehyde.