Conversion Of Benzyl Alcohol Research Articles

Preparation of CuFe2O4 composite metal oxides and selective oxidation of benzyl alcohol

Using iron nitrate and copper nitrate as raw materials, mesoporous material SBA-15 as template agent and n-hexane as solvent, CuFe2O4 samples of mesoporous loaded composite metal oxide catalysts were successfully prepared by calcination at 600 °C. The samples were characterized by X-ray diffraction (XRD), thermogravimetric-differential scanning analysis (TG-DSC), and scanning electron microscopy (SEM). The selective oxidation of benzyl alcohol by CuFe2O4 under different catalytic conditions was investigated using benzyl alcohol as a model compound, and the oxidation products were analyzed by high performance liquid chromatography (HPLC). The results showed that the CuFe2O4 catalyst prepared by calcination at 600°Cwas the best. The best selective oxidation conditions were achieved at a reaction system temperature of 90 °C, a catalyst dosage of 4 g/L, a molar ratio 1:1 of H2O2 dosage to benzyl alcohol, and a reaction time of 4 h. The conversion of benzyl alcohol under this condition was 66.95%, and the selective conversion of benzaldehyde was 96.07%. This indicates that CuFe2O4 is a composite metal oxide with high selective oxidation of benzyl alcohol and has wide application prospects.

Self-Assembly of Porous Hierarchical BiOBr Sub-Microspheres for Efficient Aerobic Photooxidation of Benzyl Alcohol under Simulated Sunlight Irradiation

Semiconductor photocatalytic performances can be modulated through morphology modification. Herein porous hierarchical BiOBr microspheres (BiOBr-MS) of ~3 μm was firstly self-assembled without the assistance of a template via a facile solvothermal synthesis in triethylene glycol (TEG) at 150 °C for 3 h. KBrO3 was exploited as a bromine source, which slowly provided bromide ions upon reduction in TEG and controlled the growth and self-assembly of primary BiOBr nanoplates. The addition of PVP during solvothermal synthesis of BiOBr-MS reduced the particle size by about three-fold to generate BiOBr sub-microspheres (BiOBr-sMS) of <1 μm. BiOBr-sMS exhibited significantly higher photocatalytic activity than BiOBr-MS for aerobic photooxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) under simulated sunlight irradiation (conversions of BzOH (50 mM) over BiOBr-sMS and BiOBr-MS were, respectively, 51.3% and 29.6% with 100% selectivity to BzH after Xenon illumination for 2 h at 25 °C). The photogenerated holes and ·O2− were found to be main reactive species for the BzOH oxidation over BiOBr spheres by scavenging tests and spin-trapping EPR spectra. The higher photocatalytic activity of BiOBr-sMS was attributed to its more open hierarchical structure, efficient charge separation, more negative conduction-band position and the generation of larger amounts of ·O2−.

Boosting photocatalytic dehydrogenation and simultaneous selective oxidation of benzyl alcohol to benzaldehyde over flower-like MoS2 modified Zn0.5Cd0.5S solid solution

A series of MoS2/Zn0.5Cd0.5S with varying concentrations of flower-like MoS2 is prepared based on a simple and practical method with highly efficient photocatalytic dehydrogenation and simultaneous selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). A comparative study between the composites and their two components (pristine MoS2 and Zn0.5Cd0.5S) is carried out for various structural, optical, electrical, and photocatalytic characterization. The studies reveal that the size of Zn0.5Cd0.5S nanoparticles is in the order of 3∼5 nm and is distributed uniformly over the surface of the flower-like 350 nm sized MoS2. The optical research conducted using UV–vis diffuse reflectance spectroscopy reflecting an excellent photoresponse by the MoS2/Zn0.5Cd0.5S. The photoelectrochemical tests showed that the adding of proper ratio of flower-like MoS2 (6%) results in an efficient separation and migration of photogenerated carriers for pristine Zn0.5Cd0.5S nanoparticles. The photocatalytic dehydrogenation rate of BA for the 6%-MoS2/Zn0.5Cd0.5S is the highest at 3.03 mmol g−1 h−1, meanwhile the yield of BAD and the selective conversion of BA to BAD are 49.3% and 100%, respectively. The essential stages of the photocatalytic dehydrogenation of BA are ·C caused by the photo-generated holes, according to the EPR spectra of the PBN-carbon centered radical (PBN–C). Besides, the mechanism for improved photocatalytic dehydrogenation and synergistic selective oxidation of BA to BAD with flower-like MoS2 modified Zn0.5Cd0.5S nanoparticles was systematically studied through gas chromatography-mass spectrometry analysis and first principle density functional theory calculations. The highly efficient dehydrogenation and synergistic selective oxidation of BA to BAD for MoS2/Zn0.5Cd0.5S are mainly attributed to the introduction of MoS2 nanoflowers that can provide abundant active sites, and formed MoS2/Zn0.5Cd0.5S heterostructures could further promote the separation of photogenerated electron-hole pairs. Moreover, the valance band position of the 6%-MoS2/Zn0.5Cd0.5S is more positive, so the hole at the VB position has the stronger ability to oxidize BA. This study provides a feasible method for efficiently photocatalytic dehydrogenation synergism selective oxidation of organic substrates into valuable products.

New reaction pathway induced by N-deficient conjugated polymer-supported bimetallic oxide quantum dot S-scheme heterojunction for benzyl alcohol oxidation in water

The catalytic conversion of aromatic alcohols to their corresponding carbonyls under mild conditions is challenging because of their low selectivity and activity. A 0D/2D based S-scheme heterojunction material with bimetallic oxide quantum dots (NixFe1-xO QD) and nitrogen-deficient conjugated polymers, such as g-C3N4 (NvCN), was designed for the photocatalytic conversion of benzyl alcohols to benzaldehyde/benzoic acid using simulated solar light. The optimized Ni0.5Fe0.5O QD/NvCN (NFO/NvCN) hybrid catalyst exhibited excellent conversion (85%) and selectivity (98%) for photocatalytic oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) in an aqueous medium (88%) and for benzoic acid (BzA) under dilute alkaline conditions (99%). The structure-activity relationship was established using catalytic activity data, surface physicochemical characteristics, optoelectronic characteristics, and scavenging studies. The band alignment of the heterojunction converts the type-I junction into a type-II junction and follows S-scheme charge dynamic pathways through the nitrogen vacancy pathways, which can accelerate the separation and transfer of photogenerated charge carriers. Mechanistic pathways have been proposed based on O–H bond cleavage by electrons and C–H bond cleavage by holes. Hybrid materials based on defect-rich supports and bimetallic oxide-quantum dot interactions are promising catalysts that can compete with the best photocatalysts.

Pickering emulsion enhanced interfacial catalysis under Taylor flow in a microchannel reactor

There are still technical challenges associated with surface fouling and clogging in microchannels when conducting multiphase catalytic reactions involving solid particles. In this study, a Pickering emulsion was employed to enhance the oxidation of benzyl alcohol (BNOH) catalyzed by Pd/SiO2 nanoparticles under Taylor flow in a microchannel reactor. The reaction characteristics of benzyl alcohol/water Pickering emulsion in a microchannel reactor were studied experimentally. The characteristic results showed that the O/W Picking emulsion system was superior to the W/O Picking emulsion system for the catalytic oxidation reaction. The influences of a wide range of operational variables were characterized on the conversion of reactants and the selectivity of the desired product. The optimized reaction conditions included: reaction temperature 403 K, CB 5 wt%, O2/BNOH (mol/mol) 0.76 and tube length 8 m. Under the optimal operating conditions, the conversion of BNOH and the selectivity of benzaldehyde were found to be 86.53% and 99.79%, respectively. In addition, the interfacial transport-reaction mechanism in Pickering emulsions under Taylor flow in microchannels was proposed from the perspective of multiphase mass transfer. This development provided significant insights and guiding for effectively performing multiphase catalytic reactions involving solid catalyst particles in microchannel reactors.

Radial Nano-Heterojunctions Consisting of CdS Nanorods Wrapped by 2D CN:PDI Polymer with Deep HOMO for Photo-Oxidative Water Splitting, Dye Degradation and Alcohol Oxidation.

Solar energy harvesting using semiconductor photocatalysis offers an enticing solution to two of the biggest societal challenges, energy scarcity and environmental pollution. After decades of effort, no photocatalyst exists which can simultaneously meet the demand for excellent absorption, high quantum efficiency and photochemical resilience/durability. While CdS is an excellent photocatalyst for hydrogen evolution, pollutant degradation and organic synthesis, photocorrosion of CdS leads to the deactivation of the catalyst. Surface passivation of CdS with 2D graphitic carbon nitrides (CN) such as g-C3N4 and C3N5 has been shown to mitigate the photocorrosion problem but the poor oxidizing power of photogenerated holes in CN limits the utility of this approach for photooxidation reactions. We report the synthesis of exfoliated 2D nanosheets of a modified carbon nitride constituted of tris-s-triazine (C6N7) linked pyromellitic dianhydride polydiimide (CN:PDI) with a deep oxidative highest occupied molecular orbital (HOMO) position, which ensures sufficient oxidizing power for photogenerated holes in CN. The heterojunction formed by the wrapping of mono-/few layered CN:PDI on CdS nanorods (CdS/CN:PDI) was determined to be an excellent photocatalyst for oxidation reactions including photoelectrochemical water splitting, dye decolorization and the photocatalytic conversion of benzyl alcohol to benzaldehyde. Extensive structural characterization using HR-TEM, Raman, XPS, etc., confirmed wrapping of few-layered CN:PDI on CdS nanorods. The increased photoactivity in CdS/CN:PDI catalyst was ascribed to facile electron transfer from CdS to CN:PDI in comparison to CdS/g-C3N4, leading to an increased electron density on the surface of the photocatalyst to drive chemical reactions.

Dual-functional reaction strategy boosts carbon dioxide reduction by coupling with selective benzyl alcohol oxidation on nano-Au/BiOCl photocatalysts

Photocatalytic CO2 reduction without using sacrificial agents remains a big challenge. Herein, we report a dual-functional reaction on the Au-decorated 3-dimensional BiOCl nano-photocatalyst (Au/3D-BOC) that couples photocatalytic CO2 reduction with benzyl alcohol (BA) oxidation. On the optimized 1.0% Au/3D-BOC photocatalyst, the CO production rate reached 0.17 µmol cm-2 h−1 under AM 1.5 solar simulator light source, and the BA conversion was 48.04% with benzaldehyde (BAD) selectivity above 99%. The density functional theory (DFT) calculations demonstrate the decrease of the reaction thermodynamic energy barriers after loading Au. And various characterizations reveal the dependence of the interaction between Au NPs and 3D-BOC on Au loading, which is essential to separating photogenerated carriers and prolonging their lifetime. On this basis, the reaction pathways of CO2 photoreduction and selective BA oxidation over Au/3D-BOC were proposed. This work provides a new approach to promoting CO2 reduction and BA oxidation with high economic benefits.

Poly(dibenzothiophene-S,S-dioxide)-Fe2O3 heterojunction for photocatalytic hydrogen production coupled with selective oxidation of benzyl alcohol

Photocatalytic conversion of benzyl alcohol (BA) into value-added fine chemicals and hydrogen (H2) in water medium provides a novel strategy for green synthesis. The construction of Z-scheme heterostructures not only realize enhanced charge-separation efficiency, but also remain strong drive force for photocatalytic reaction, which exhibit great potentials toward simultaneously generating benzaldehyde (BAD) and H2. Herein, we report a noble-metal-free Z-scheme photocatalytic system consisting poly(dibenzothiophene-S,S-dioxide) (PSO) and α-Fe2O3 for selective oxidation of BA with synchronous H2 production. Such nanocomposites can effectively transfer and reduce the recombination of photoexcited charge carriers, therefore maintaining the oxidizability of holes of α-Fe2O3 and the reducibility of electrons of PSO. As expected, PSO-Fe2O3 with a mass of ∼5 mg under optimal composition ratio exhibited an impressive photocatalytic activity with BAD and H2 yields up to 23.1 and 29.5 μmol h−1, respectively, which is among the top photocatalytic performance reported so far for selective photocatalytic oxidation of BA in the aqueous solution.

Liquid-phase benzylation of toluene by benzyl alcohol over micro-mesoporous hierarchical mordenite zeolite.

In this work, post-synthetic effective acid (HNO3) and base (NaOH) etching technique are used to create hierarchical mordenite having different pore structure. The powder X-ray diffraction (P-XRD) technique was used to confirm the crystalline structure of the base-modified and acid-modified mordenite. Field emission-scanning electron microscope (FE-SEM) was employed to confirm the structural morphology of the materials. The modified mordenite was further characterised by inductive coupled plasma-optical emission spectrometry (ICP-OES), N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), and acid-base titration, to confirm the structural integrity, presence of active acidic sites, and other vital parameters. The structure was well conserved after the change, as evidenced by the characterisation. The toluene benzylation with benzyl alcohol using hierarchical mordenite and H-mordenite produced mono-benzylated toluene. Comparison between acid treated, base treated, and H-mordenite was done. All samples were catalytically active as proved by the catalytic result in the benzylation reaction. The results show that the base alteration dramatically enhances the mesoporous surface area of H-mordenite. Furthermore, the acid-treated mordenite had the highest benzyl alcohol conversion (75%), but the base-modified mordenite had benzyl alcohol conversion of 73% with the highest mono-benzylated toluene selectivity (61%). The process was further optimised by varying the reaction temperature, duration, and catalyst quantity. Gas chromatography (GC) was used to evaluate the reaction products and gas chromatography-mass spectrometry (GC-MS) was used to confirm them. Introduction of mesoporosity in the microporous mordenite was found to have significant effect on their catalytic activity.

Green Catalytic Conversion of Some Benzylic Alcohols to Acids by NiO2 Nanoparticles (NPNPs) in Water

The aqueous basic systems NiSO4·6H2O/K2S2O8 (pH = 14) and NiSO4·6H2O/KBrO3 (pH = 11.5) were investigated for the catalytic conversion of benzyl alcohol and some para-substituted benzyl alcohols to their corresponding acids in 75–97% yields at room temperature. The active species was isolated and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction, EDX and FT-IR techniques, and identified as comprising NiO2 nanoparticles (NPNPs). The SEM and TEM images of the Ni peroxide samples showed a fine spherical-like aggregation of NiO2 molecules with a nearly homogeneous partial size and confirmed the aggregation’s size to be in the range of 2–3 nm. The yields, turn over (TO) and turn over frequencies (TOF) were calculated. It was noticed that the aromatic alcohols containing para-substituted electron donation groups gave better yields than those having electron withdrawing groups. The optimum conditions for this catalytic reaction were studied using benzyl alcohol as a model. The mechanism of the catalytic conversion reaction was suggested, in which the produced NPNPs convert alcohols to acids in two steps through the formation of the corresponding aldehyde. The produced NiO because of this conversion is converted again to NPNPs by the excess of K2S2O8 or KBrO3. This catalytic cycle continues until all of the substrate is oxidized.

Selectively Permeable FeOOH Amorphous Layer Coating CdS for Enhancing Photocatalytic Conversion of Benzyl Alcohol and Selectivity to Benzaldehyde.

The development of new strategies to improve reaction efficiency and light utilization is one of the biggest challenges in photosynthetic chemistry. Dynamics control, particularly tuning the adsorption/desorption of reactants and products, is an ideal way to improve the conversion and selectivity in catalytic reactions, but it is rarely studied for photocatalytic organic synthesis. This study concerns the design of an amorphous FeOOH coating to decorate CdS photocatalyst to control the adsorption and desorption of reactants and products to improve reaction efficiency for the photocatalytic conversion of benzyl alcohol (BA) into benzaldehyde (BAD). The best conversion of the core-shell photocatalyst is 74.1 % in 2 h, together with >99.9 % selectivity to BAD, and the photocatalyst exhibits response above 600 nm, which is the longest active wavelength reported for the reaction. Further data illustrate that the amorphous FeOOH coating enables selective sorption of BA/BAD molecules by H-bonding interactions, which may result in the excellent performance. Construction of amorphous coating layers and understanding the selective permeability may provide a new strategy for the design of more efficient photocatalytic systems for organic synthesis.

Insights into Active Sites and Mechanisms of Benzyl Alcohol Oxidation on Nickel–Iron Oxyhydroxide Electrodes

The electrochemical oxidation of bio-derived molecules has recently garnered interest for its potential in opening electrified synthetic pathways toward value-added products. Herein, we investigate the electrochemical conversion of benzyl alcohol (BA) to benzaldehyde and benzoate on nickel–iron (Fe ∼ 7–18%) electrodes as a model system to understand reaction mechanisms and environmental conditions that can transform these molecules. Our results indicate a strong correlation between benzyl alcohol oxidation (BAO) onset potentials and Ni(II/III) redox peak positions, highlighting the potential role that lower oxidation states of nickel, i.e., Ni3+, can play in BAO catalysis. Our work on the Ni2+/3+ system complements mechanisms that involve higher oxidation states of Ni as reported by others. We note that the Ni redox position and thus BAO onset is impacted by Fe incorporation during electrochemistry from unpurified electrolytes, which can resemble standard reactor operating conditions. We perform a systematic computational investigation into BAO and provide density functional theory (DFT) insights into how the redox mechanism has been such a prominent focus of alcohol oxidations. This includes the mode of BA adsorption and the nature of the adsorption site; upon conversion of the Ni2+ surface to active Ni3+ via hydroxyl deprotonation, BAO is thermodynamically downhill. Our DFT study also introduces the possibility of a vacancy-driven mechanism, though expected to be less prevalent during catalysis than the redox mechanism for a Ni3+ surface. Through the systematic investigation of experimental reaction conditions and computational free energy thermodynamics, we have gained valuable insights into BAO reaction mechanisms that inform catalytic activity. Our study opens avenues for further design and development of catalyst active sites for the oxidation of related organic molecules.

Constructing a Z-scheme Fe-MOF-based heterostructure for visible-light-driven oxidation of aromatic alcohol in ambient air

• Spindle-shaped MIL-53(Fe)-NH 2 @ZnIn 2 S 4 photocatalysts were facilely developed • A Z-scheme heterostructure is assuredly formed between ZnIn 2 S 4 and MIL-53-NH 2 • The photocatalytic BA conversion can be notably enhanced in ambient air • The benzaldehyde production rate can surpass most studies in air, O 2 or inert gas Photocatalytic oxidation of aromatic alcohol into aromatic aldehyde using O 2 has received huge attention, while the reaction that occurred in ambient air is rarely studied but follows the green-chemistry principles. Herein, spindle-shaped MIL-53(Fe)-NH 2 @ZnIn 2 S 4 photocatalysts with a Z-scheme heterostructure were facilely developed for photocatalytic oxidation of aromatic alcohol in air under visible light. The benzyl alcohol conversion can be notably enhanced to 73% over the optimal MIL-53-NH 2 @ZnIn 2 S 4 sample with a benzaldehyde production rate of 1825 μmol g –1 h –1 . However, in the O 2 atmosphere, the benzyl alcohol conversion is only 56%, indicating that O 2 is not required and has an adverse effect on the reaction. The hierarchical structure and Z-scheme heterojunction of MIL-53-NH 2 @ZnIn 2 S 4 impart an efficient separation and strong redox abilities of photo-induced electrons and holes, which are responsible for the impressive photocatalytic performance. This study could motivate the ingenious design of Z-scheme heterostructures for green organic conversion based on MOFs.

Structure - Catalytic Activity Correlation in Aluminium Hydroxide Supported Vanadia Catalysts

Aluminium hydroxide samples containing vanadium in the range 5 - 25 wt % have been prepared by incipient wetness impregnation method. The catalysts have been characterized through % composition of vanadium, BET surface area, FTIR, PXRD, SEM and solid state V-NMR. Liquid phase conversion of benzyl alcohol over the above materials into various products has been used as a chemical probe to investigate the activity of these catalysts. Benzyl alcohol has been converted into benzaldehyde, toluene and 1, 2-diphenyl ethane (dibenzyl). Formation of various products at different loadings of vanadium is found to be related to structural features of vanadium oxo-species. Oxidation- reduction products and 1, 2-diphenyl ethane have been formed selectively, at lower loadings of vanadium, which was in the tetrahedral environment of oxygen and at higher loading when vanadium was in square pyramidal environment catalytic activity increased but with low selectivity. When aluminum hydroxide was used as a support monolayer coverage was completed only at higher loading indicating better dispersion of metal - oxo species over this support.

Solvent-free efficient oxidation of benzyl alcohol on nano-Pd/Al2O3: Effect of palladium source and pH value

PA-Na-x and PA-H-1 catalysts were prepared by a cation-assisted polyol method using different Pd sources (Na2PdCl4 or H2PdCl4) and pH values (x = 1, 2, 3 or 5), and applied to solvent-free oxidation of benzyl alcohol (BzOH). As confirmed by multiple analytical characterizations, the base number, Pd0 content and abundance of oxygen vacancies for PA-Na-x prepared were higher than those on PA-H-1, and their synergistic effect made PA-Na-x possess the higher BzOH conversion and benzaldehyde selectivity. The contents of Pd0 and oxygen vacancies on PA-Na-x showed an inverted volcano trend with the increase of the pH value. PA-Na-x also followed the inverted volcano order for the catalytic activity, where PA-Na-1 prepared from Na2PdCl4 at pH 1 exhibited the best catalytic efficiency with a turnover frequency of 29.5 s−1 and 94.8% selectivity of benzaldehyde, and excellent stability. This study provided an efficient method of preparing nano-Pd catalysts.

KINETICS OF SEMI-BATCH OXIDATION OF BENZYL ALCOHOL TO BENZALDEHYDE BY USING SULFATED FE-TIO2 CATALYST

Liquid phase semi-batch oxidation of benzyl alcohol to benzaldehyde was carried out by using a novel sulfated Fe-TiO<sub>2</sub> (designated as ICaT-3) solid catalyst by using hydrogen peroxide as oxidant and cetyltrimethylammonium bromide (CTAB) as phase transfer co-catalyst. ICaT-3 was characterized by Fourier-transform infrared, X-ray diffraction, thermogravimetry differential thermal analysis, surface area measurements, ammonia temperature-programmed desorption, scanning electron microscopy, and energy dispersive X-ray analysis. Under optimized reaction conditions, ICaT-3 gave 55% of benzyl alcohol conversion and 96% benzaldehyde selectivity, whereas pure TiO<sub>2</sub> gave only 14% of benzyl alcohol conversion. Effects of various parameters, such as speed of agitation, catalyst loading, CTAB loading, temperature, and catalyst reusability, were studied on the conversion of benzyl alcohol. It was observed that, with increasing the CTAB concentration benzyl alcohol, conversion increased up to 65%; whereas, without a phase transfer catalyst, only 4% conversion was observed. The reaction follows the Ishii-Venturello-type reaction mechanism and is first order with respect to benzyl alcohol. The value of the apparent activation energy is found to be 7.31 kcal/mol. The ICT-3 catalyst was found to be reusable.

Spontaneous generation of singlet oxygen on microemulsion-derived manganese oxides with rich oxygen vacancies for efficient aerobic oxidation.

Developing innovative catalysts for efficiently activating O2 into singlet oxygen (1O2) is a cutting-edge field with the potential to revolutionize green chemical synthesis. Despite its potential, practical implementation remains a significant challenge. In this study, we design a series of nitrogen (N)-doped manganese oxides (Ny-MnO2, where y represents the molar amount of the N precursor used) nanocatalysts using compartmentalized-microemulsion crystallization followed by post-calcination. These nanocatalysts demonstrate the remarkable ability to directly produce 1O2 at room temperature without the external fields. By strategically incorporating defect engineering and interstitial N, the concentration of surface oxygen atoms (Os) in the vicinity of oxygen vacancy (Ov) reaches 51.1% for the N55-MnO2 nanocatalyst. This feature allows the nanocatalyst to expose a substantial number of Ov and interstitial N sites on the surface of N55-MnO2, facilitating effective chemisorption and activation of O2. Verified through electron paramagnetic resonance spectroscopy and reactive oxygen species trapping experiments, the spontaneous generation of 1O2, even in the absence of light, underscores its crucial role in aerobic oxidation. Density functional theory calculations reveal that an increased Ov content and N doping significantly reduce the adsorption energy, thereby promoting chemisorption and excitation of O2. Consequently, the optimized N55-MnO2 nanocatalyst enables room-temperature aerobic oxidation of alcohols with a yield surpassing 99%, representing a 6.7-fold activity enhancement compared to ε-MnO2 without N-doping. Furthermore, N55-MnO2 demonstrates exceptional recyclability for the aerobic oxidative conversion of benzyl alcohol over ten cycles. This study introduces an approach to spontaneously activate O2 for the green synthesis of fine chemicals.

The Oxidation Behavior of Potato Starch and Benzyl Alcohol via Peroxide in the Catalysis of Metal Complexes

AbstractTwo new Schiff bases ligands (HL1 and HL2) and their Co2+, Mn2+, Fe3+, Ru3+, Cr3+, and VO2+ complexes were synthesized and characterized by FT‐IR, 1H‐NMR, and Mass spect. and analytical methods. A single‐crystal X‐ray diffraction study determined the molecular structure of HL1. The catalytic effects of metal complexes on benzyl alcohol and potato starch (PS) oxidation were compared in an H2+O2 medium. The percent conversion of benzyl alcohol to benzaldehyde and benzoic acid was determined by Gas Chromatography. [Co(L1)2], [Mn(L1)2], [Co(L2)2], and [Mn(L2)2] showed the highest catalytic effect with a value between 97–98% in the conversion of benzyl alcohol to benzaldehyde and benzoic acid. Maximum % benzoic acid formation was observed in [Mn(L1)2] (39%) and [VO(L1)2] (58%). To determine the effect of the catalyst properties of the complexes on the oxidation of PS, carbonyl and carboxyl groups formed in potato starch were determined by the titrimetric method, and PS oxidation degrees were calculated as DS (DSCHO and DSCOOH). In potato starch oxidation, the [VO(L1)2] had the highest catalytic effect with DSSum = 0.96, while the [Mn(L1)2] had a relatively lower DSSum = 0.86 value. On the other hand, the [Cr(L2)2ClH2O] showed a catalytic impact with DSSum = 0.63.

Synthesis of Hierarchical Micro-mesoporous ZSM-5 Zeolite and its Catalytic Activity in Benzylation of Mesitylene

Hierarchical micro-mesoporous ZSM-5 (MFI type) zeolite was synthesized by using corn plant stem pith powder from agricultural waste as hard template under simple hydrothermal method. The additional porosity generated using this pith powder into the zeolites precursor gel yielded hierarchical micro-mesoporous ZSM-5 zeolite (C-ZSM-5). Conventional micro porous ZSM-5 (ConvZSM-5) was also prepared by same procedure without adding the corn stem pith powder to compare the catalytic performances. The prepared C-ZSM-5 zeolite exhibited 89% conversion, much greater than ConvZSM-5 (33%). Selectivity in the formation of 2-Benzyl-1, 3, 5-trimethylbenzene, by benzylation with C-ZSM-5 (70%) is more than two times than ConvZSM-5 (32%). This benzylation can be used as a test reaction to evidence the formation of hierarchical micro-mesoporous nature of the material. C-ZSM-5 exhibited better selectivity and benzyl alcohol conversion due to the presence of hierarchical pores and strong acidy in C-ZSM-5.The product formed in the above reaction was separated and further confirmed by 1HNMR and 13CNMR. Even after consecutive recycles every month for three months, the conversion and desired products selectivity had not been affected. The hierarchical pores present in the catalyst further improved the stability of the zeolites. Hence this catalyst could be very useful for industrially important reactions.

Modulating the electronic structure of Co-Ni bimetal oxides on mesoporous silica for promoting selective oxidation of alcohol

The selective oxidation of alcohols by transition-metal-based catalysts provides a green route for the production of aldehydes. In this paper, mesoporous SBA-15 supported bimetallic NixCoy oxides were synthesized for the catalytic oxidation of alcohol using oxygen as the sole oxidant. The catalytic activity was highly related to the metal composition, of which the Ni1Co4/SBA-15 catalyst showed the best catalytic performance with high benzyl alcohol conversion of 96.2% and benzaldehyde selectivity of 98.3%. It was proposed that the electronic structure of the NixCoy/SBA-15 catalysts can be modulated by Ni/Co ratio, and high Co3+/Co2+ and Ni3+/Ni2+ ratios promoted the catalyst activity. Compared to the NixCoy nanocatalysts obtained by removing SBA-15 support, the NixCoy/SBA-15 exhibited a better benzyl alcohol oxidation performance, suggesting a diffusion enhancement by the mesoporous structure of SBA-15 support.