One-step synthesis of nitriles by the dehydrogenation–amination of fatty primary alcohols over Cu/m-ZrO2

An effective method for one-step synthesis of nitriles employing C₂–C₈ fatty primary alcohols and ammonia over 5%Cu/m-ZrO₂ has been found. The conversion of alcohols and selectivity of nitriles obtained are > 96 and > 87 wt.%, respectively, and are obviously influenced by the C2-substitution rather than the chain length of fatty primary alcohols. Cu/m-ZrO₂ was characterized by XRD, H₂-TPR, CO₂-TPD and NH₃-TPD. It is revealed that a substantial amount of Cu species over m-ZrO₂ is in highly dispersed CuO. A plausible mechanism is proposed and supported by different experiments, and aldehyde generation is an important step in the reaction mechanism.     

Novel metal oxide nanocomposite of Au/CuO–ZnO for recyclable catalytic aerobic oxidation of alcohols in water

CuO–ZnO supported gold nanoparticle is introduced as a new, efficient, and recyclable catalyst for the aerobic oxidation of alcohols. The CuO–ZnO support was prepared by co-precipitation and Au nanoparticles were loaded on support by a deposition–precipitation method. The catalyst was characterized by XRD, BET surface area, FESEM, EDS and HRTEM techniques. A wide range of alcohols, including benzylic, primary and secondary alcohols are converted into the corresponding carbonyl derivatives. The experimental procedure with Au/CuO–ZnO catalyst is quite straightforward and the catalyst is recyclable up to 6 consecutive runs by simple filtration.     

Destruction of toxic organics in water by an injection‐type downflow UV/O3 oxidation reactor

An injection‐type downflow UV/O₃ oxidation reactor (IDUOR) was developed mainly with the combination of a configuration of two concentric cylinders with the UV lamp in the bottom axial position and a downflow mixing gas‐liquid injector. This configuration leads to atomizing of the solution resulting in higher levels of dissolved ozone which is then illuminated by UV light to generate hydroxyl radicals. Four different toxic wastewaters including 4‐chlorophenol, carbofuran, dye‐auxiliaries and pesticide wastewater with a COD range of 164 to 1602 mg/L and a microtoxicity (EC₅₀) range of 3.008% to 19.062% were used to investigate the performance of the device. It was found that the ozone utilization efficiency attained was more than 75% with very satisfying COD and TOC reduction for wastewater treated with IDUOR. The IDUOR when compared to a conventional stirred bubble UV/O₃ reactor exhibited increased efficiency for ozone utilization and COD, TOC, microtoxicity reduction. Also, the pseudo‐first rate constants on the basis of COD and TOC reduction indicated much higher oxidation rate of organics in IDUOR, providing additional evidence of the considerable treatment potency of IDUOR for destruction of toxic organics in water.     

Preparation optimization of multilayer-structured SnO2–Sb–Ce/Ti electrode for efficient electrocatalytic oxidation of tetracycline in water

In this study, electrodeposition and thermal decomposition were alternatively used for the fabrication of a series of novel multilayer-structured SnO₂-Sb-Ce/Ti (SSCT) electrodes, and their physiochemical and electrochemical properties were investigated for electrochemical oxidation of tetracycline (TC) in aqueous medium. Experimentally, after the SnO₂-Sb-Ce (SSC) composite was electrodeposited for 120 s on the titanium substrate in aqueous solution, the outer thermal coatings composed of SSC were synthesized by a hydrothermal method. Both influences of electrodeposition time (T_ed) and thermal decomposition time (T_td) were investigated to obtain the optimum preparation. It was found that when increasing T_ed to a certain extent a longer lifetime of electrode can be achieved, which was attributed to a more solid interlayer structure. A notable SSCT_Ted,Ttd electrode, i.e., SSCT_3,10, which was prepared through three times of 120 s' electrodeposition (T_ed=3) and ten times of thermal decomposition (T_td=10) obtained the highest oxygen evolution potential 3.141 V vs. SCE. In this selected electrode, when 10 mg·L^-1 initial TC concentration was added to this wastewater, the highest color removal efficiency and mineralization rate of TC were 72.4% and 41.6%, respectively, with an applied electricity density of 20 mA·cm^-2 and treatment time of 1 h. These results presented here demonstrate that the combined application of electrodeposition and thermal decomposition is effective in realization of enhanced electrocatalytic oxidation activity.     

One-pot tandem catalytic synthesis of α, β-unsaturated nitriles from alcohol with nitriles in aqueous phase

Pd₁–Au₁ bimetal catalysts supported on basic layered double hydroxide (LDH) have been prepared conveniently with surface impregnation methods and structurally characterized by XRD, TEM and XPS. The nanoparticles were highly dispersed on LDH with an average size of 2.08 ± 0.3 nm and showed a strong cooperative effect between Au and Pd for the step of the alcohol oxidation. Moreover, the present hydrotalcite-supported bimetal catalysts can catalyze efficiently one-pot α-arylation reactions of nitriles with various alcohols in aqueous phase through tandem reactions. The bimetal catalyst has been extended for a broad substrate scope and recycled for at least 4 times.     

Selective CO oxidation over promoted Au/γ-Al2O3 catalysts in the presence of CO2 and H2O in the feed

In this work, the effect of promoter type (Mg, Mn, Ce, Co, Fe and Ni) on selective CO oxidation performance of Au/γ-Al₂O₃ was studied with the realistic feed stream containing CO₂ and H₂O. The effects of Au loading, promoter loading, reaction temperature and the feed composition were also investigated. It was found that MgO was the best promoter in the presence of CO₂ and H₂O, and 1.25 wt.% Mg was sufficient for promotion. The CO conversion decreased with the addition of CO₂ while the presence of H₂O had some positive effects.     

A simple oxidation–reduction process for the activation of a stainless steel surface to synthesize multi-walled carbon nanotubes and its application to phenol degradation in water

Aligned multi-walled carbon nanotubes (MWCNTs) were synthesized directly on a stainless steel surface by surface activation by intense oxidation in air followed by a moderate reduction in H₂ without any wet process. This method is extremely simple compared with conventional ways that need catalyst loading steps or acid pre-etching steps to synthesize carbon nanotubes on stainless steel surfaces. It was found that the length of MWCNT bundles could reach 80 μm when the oxidation step was properly controlled. It was demonstrated that MWCNTs synthesized on stainless steel meshes could be used as a catalyst support to enhance ozone oxidation in the decomposition of phenol in water.     

Methane conversion to ethane in the presence of iron‐ and manganese‐promoted sulfated zirconia

Sulfated zirconia promoted with 1.0 wt% Fe and 0.5 wt% Mn converts methane into ethane with traces of ethylene and acetylene. The initial reaction rate at 723 K and a methane partial pressure of 20 kPa was found to be about 10^-9 mol(CH ₄) (g s)^-1, and deactivation was rapid, with the reaction rate declining to half the maximum rate within an hour. This revised version was published online in July 2006 with corrections to the Cover Date.     

Liquid-phase hydrogenation of benzene to cyclohexene catalyzed by Ru/SiO2 in the presence of water–organic mixtures

The liquid-phase hydrogenation of benzene to cyclohexene was studied using a Ru/SiO₂ catalyst prepared by reduction of ruthenium(III) chloride impregnated in a hydrophilic non-porous silica. In a biphasic water/benzene system at 423 K and 5 MPa of hydrogen pressure, a 14% cyclohexene yield was obtained at 60% benzene conversion. Increased cyclohexene yields and selectivities were observed in the presence of ethylene glycol/water and glycerol/water mixtures, which consist mainly of hydrated organic molecules that can enhance the hydrophilicity around the ruthenium particles favoring the cyclohexene desorption.     

Preparation of α-diazo-β-hydroxy esters using KOtBu in water and PEG

α-Diazo-β-hydroxy esters prepared by the interaction of aldehydes and acyldiazomethane in water in the presence KO^tBu as a catalyst in excellent yields. The catalyst displayed unprecedented catalytic activity in Aldol type reaction under mild liquid phase conditions at a greater rate compared to other known catalyst. The present catalyst is a potential alternative to the conventional bases.     

Photocatalytic activities for partial oxidation of α-methylstyrene over zeolite-supported titanium dioxide and the influence of water addition to reaction solvent

The photocatalytic reaction in the partial oxidation of α-methylstyrene (α-MS) to acetophenone (AP) was investigated for TiO₂ supported on H-ZSM-5 (H-MFI), H-mordenite (H-MOR), and H-Y-type (H-FAU) zeolites. XRD results demonstrated that the anatase was the stable phase of TiO₂ supported on zeolites. Photocatalytic activities of supported catalysts decreased in the following order: TiO₂/H-MFI >> TiO₂/H-MOR > (TiO₂) > TiO₂/H-FAU >> (blank). TiO₂/H-MFI catalyst exhibited the best performance for photocatalytic oxidation of α-MS to AP. The maximal activity was obtained by 25 wt% TiO₂/H-ZSM-5. The addition of water to the reaction solvent resulted in significantly lowering the photocatalytic activity for TiO₂/H-ZSM-5 catalyst, although its activity for TiO₂ and TiO₂ + H-ZSM-5 mechanical mixture was little influenced by the amount of water added to reaction solvent.     

Water‐promoted ammonia oxidation by a platinum amine complex in zeolite HZSM‐5 catalyst

In this study it was found that [Pt(NH₃)₄]HZSM‐5 is an active catalyst for the oxidation of ammonia at low temperature that, in contrast with other catalysts, becomes more active in the presence of water. Furthermore, the selectivity to nitrogen was found to increase when water is present. This revised version was published online in July 2006 with corrections to the Cover Date.     

Biosynthesis of glycyrrhetic acid 3-O-mono-β-D-glucuronide by whole cell in ionic liquid/water biphasic system

研究了水/离子液体两相体系中重组毕赤酵母Pichia pastoris GS115（r-PGUS-P）全细胞转化甘草酸（GL）生成单葡萄糖醛酸基甘草次酸（GAMG）的反应。确定最适反应体系为离子液体［BMIM］PF₆/水（2∶8,体积比）,最适缓冲液pH、反应温度、底物浓度和细胞加入量分别为5.4、45℃、6.0 mmol·L^-1和8.0 g·L^-1。在此条件下反应58 h,产物GAMG得率和化学键选择性分别为69.6%和67.2%,与纯水相反应体系相比,分别提高了12.4%和12.61%。离子液体循环使用7次后,回收利用率为93.47%。产物GAMG和副产物甘草次酸（GA）在此两相体系中得到有效分离,为后续产物分离带来便利。     

Selective oxidation of HMF to DFF using Ru/γ-alumina catalyst in moderate boiling solvents toward industrial production

Selective oxidation of 5-hydroxymethyl-2-furfural (HMF) to 2,5-diformylfuran (DFF) toward industrial production was studied over Ru supported γ-alumina catalyst using molecular oxygen as an oxidant. From the solvents screening, considering recyclability after reaction, toluene was found to be the best solvent and gave maximum conversion of 99% with 97% DFF selectivity at 130 °C and 40 psi O₂ pressure. Catalyst was washed with NaOH solution of pH = 12 to remove the adsorbed polymer impurities and then reused up to 5 cycles. The product could be purified by simple evaporation of the solvent, which could add advantage for industrial process.     

Development of reaction–diffusion DFT and its application to catalytic oxidation of NO in porous materials

The reaction–diffusion (RD) process is an important and complex subject that involves nonequilibrium modeling and multiscale calculations and may be applied to multiple fields. State-of-art theories are computationally too expensive for real-world applications. We propose a novel classical density functional theory (CDFT) for RD modeling by combining ordinary time-dependent density functional theory (TDDFT) and reaction kinetic models to examine the multiscale RD process. The theory is applied to NO oxidation in porous materials. The uptake, flux, and density profiles are examined, to reveal that the shape of the pore could influence the selectivity of adsorption between the reactant and product, which further leads to variations in the catalytic efficiency. It is noted that open pores are more favorable for catalytic reactions. The importance of adsorption is examined in the presence as well as the absence of pore–gas attraction. Without attraction, the catalytic efficiency is decreased by three orders of magnitude.     

Dietary cyanidin 3-O-β-d-glucoside increases ex vivo oxidation resistance of serum in rats

The effect of dietary cyanidin 3-O-β-d-glucoside (C3G), a typical anthocyanin pigment, on the generation of thiobarbituric acid reactive substances (TBARS) during serum formation ex vivo and susceptibility of serum to further lipid peroxidation was studied in rats. Rats were fed a diet containing C3G (2 g/kg) for 14 d. Feeding C3G resulted in a significant decrease in generation of TBARS during serum formation. The serum from the C3G-fed group showed a significantly lower susceptibility to further lipid peroxidation provoked by 2,2′-azobis (2-amidinopropane)hydrochloride or Cu²⁺ than that of the control group. No significant differences were observed in serum phospholipid, triglyceride, esterified cholesterol, and free fatty acid concentrations between the control and the C3G-fed groups. Concentrations of endogenous antioxidants remaining in the serum after blood coagulation were not affected by the C3G feeding. These results demonstrate that feeding C3G increases the ex vivo oxidation resistance of the serum without affecting serum endogeneous antioxidant levels, and reduces the TBARS generated during serum formation without changing the concentrations of serum lipids.     

Supercritical water oxidation—Current status of full-scale commercial activity for waste destruction

After more than three decades since its potential was first recognized, supercritical water oxidation (SCWO) remains an innovative and viable treatment technology for destruction of aqueous based organic wastes. An extensive data base of destruction efficiencies, corrosion data, and salt phase behavior has been developed over the years through the combined efforts of many investigators at both the fundamental research and commercial level. As a result, SCWO technology has been increasingly utilized in a variety of full-scale designs and applications, handling feeds as diverse as polychlorinated biphenyls (PCBs), sewage sludge, spent catalysts, and chemical weapons. This paper reviews the status of current full-scale commercial SCWO facilities around the world, focusing on the unique challenges and design strategies employed by different companies for corrosion and salt precipitation control in each application. A summary of past commercial SCWO activity as well as future plans among the current active SCWO companies is also included.     

α-gel prepared in sodium methyl stearoyl taurate/behenyl alcohol/water system-characterization of structural changes with water concentration

In this study, the changes in the structural and physicochemical properties of an α-crystalline phase (often called an "α-gel") were assessed in a sodium methyl stearoyl taurate (SMT)/behenyl alcohol/water system. The α-gels were characterized focusing on the effects of the alcohol/surfactant ratio and water concentration. Water molecules solubilized in the interlayer of the α-crystalline phase resulting in expanded interlayer spacing. Beyond the solubilization limit of 85 %, water molecules were trapped in the matrix of the α-crystalline phase in non-equilibrium (i.e., two phases). Accordingly, different self-diffusion coefficients for the solubilized and trapped water molecules were measured using a Fourier transform pulsed gradient spin echo technique to monitor the 1H NMR spectra. It was concluded that the two self-diffusion coefficients correspond to the water solubilized in the interlayer, i.e., "slow water," and trapped in the matrix of the α-crystalline phase, i.e., "fast water."     

Hydrazine drastically promoted Fenton oxidation of bisphenol A catalysed by a FeIII–Co Prussian blue analogue

Herein, for the first time it has been demonstrated that hydrazine (Hz) could significantly promote the bisphenol A (BPA) degradation in the Fenton reaction catalysed by Fe[Co(CN)₆]2H₂O Prussian blue analogue (Fe^III–Co PBA). Results indicate that the dramatic enhancement of BPA degradation could be partly attributed to the induced homogeneous Fenton reaction by the enhanced dissolution of Fe^III–Co PBA. Meanwhile, the Hz coordinated iron site (H₂NH₂N–Fe), which is evolved from the original water coordinated iron site (H₂O–Fe), was identified as the main active site. A possible reaction pathway involving the proposed active iron species was proposed.     

Er/β-zeolite-catalyzed one-pot conversion of cellulose to lactic acid

Various Er/β-zeolite catalysts were prepared by grafting erbium species in aqueous solutions of erbium chloride onto β-zeolites. The catalysts were characterized using X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy, N₂ physical adsorption, powder X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and NH₃ temperature-programmed desorption. These catalysts were evaluated in the one-pot hydrothermal conversion of cellulose to lactic acid. Lactic acid yields of approximately 58 % were obtained using an erbium grafted on de-aluminated β zeolite (Er/deAlβ-2) with an erbium content of 12.4 wt% and a Si/Al ratio of 159:1. In catalyst recycling tests, the lactic acid yield decreased from 57.9 % in the first cycle to 51.2, 49.8 and 49.6 % in the second, third and fourth cycles, respectively. The decreases in catalytic activity during recycling are proposed to arise mainly from a combination of erbium ion leaching, deposition of carbon species in the zeolite pores and the partial structure collapse.