Ni-Zr-Ce／Al2O3催化剂上H2O2作氧化剂直接使苯氧化胺化一步合成苯胺研究

设计制备了Ni-Zr-Ce/Al_2O_3催化剂,研究了其上用H_2O_2直接将苯氧化胺化 合成苯胺的活性。发现在常压、50 ℃的温和条件下,该催化剂对苯、氨水与 H_2O_2直接氧化胺化生成苯胺有较好活性,并且其对苯胺的选择性远远大于对苯酚 的选择性。提高反应原料中氨水对苯的比例,能提高苯胺的收率,且不会增加苯酚 的生成量。本方法能耗低,原子利用率高,为苯胺的绿色合成提供了一条新的路径 。     

Thermal treatment of zeolitic tuff

In this study, the zeolitic tuffs having clinoptilolite obtained from Bigadic region of western of Anatolia, Turkey were investigated as regards to whether it is possible to be transformed into amorphous phase from them. At first, the zeolite tuffs rich in clinoptilolite were characterized using XRD, DTA, TG, DSC, and FTIR standard methods. All the samples were heated at 110 °C for 2 h and then were expanded within 5 min between the temperatures 1200 and 1400 °C. In addition, porosity and density were determined. The resistance values of all the samples were measured in acidic and basic media. These samples were also analyzed. As a result of this study, zeolitic tuffs in clinoptilolite were transformed into amorphous phase, and especially in chemical industry were found convenient.     

Infrared reflection-absorption spectroscopy of polyacrylonitrile on copper and aluminium surfaces

Infrared reflection-absorption spectroscopy has been used to study the chemical structure of thin films of pyrolyzed polyacrylonitrile (PAN) on copper and aluminium surfaces. The formation of a conjugated C? C?C backbone occurs at temperatures as low as 200°C for PAN on copper, whereas the same reaction on aluminium requires pyrolysis at 300°C in order to be completed. These temperatures are, respectively, about 200 and 100°C lower than those previously reported for bulk PAN. Pyrolysis of PAN on copper at 200°C also results in diffusion of copper atoms (ions) into the polymer network followed by Cu(I)? N°C complexing. Conclusive evidence is obtained for end-on coordination through nitrogen lone pair orbitals of the C?N groups. We propose a chemical structure of PAN on copper that is different to that in the bulk and on aluminium.     

Mineralogical and chemical investigation of Tunisian phosphate washing waste during calcination

Phosphate washing waste (PWW) is one of the wastes generated by the phosphate mine with a very high amount. This waste was investigated in this work to study the effect of the calcination of the PWW at four different temperatures 600 °C, 700 °C, 800 °C and 900 °C on its mineralogical and chemical composition. The samples were investigated by X-ray powder diffraction, Fourier transform infrared, differential scanning calorimetry and thermogravimetric analysis, solid-state magic angle spinning nuclear magnetic resonance of ²⁹Si, ²⁷Al and ³¹P and scanning electron microscope. The results show that the PWW presents a complex system and it suffers a significant change on its mineralogical and chemical composition after calcination. It reveals the presence of carbonate, natural zeolite, fluorapatite, quartz and clay. After calcination, the waste shows the disappearance of some of these phases and the appearance of others and some other phases remain steady.

     

Pyrolysis study of sewage sludge by TG-MS and TG-GC-MS coupled analyses

The pyrolysis of an urban plant sewage sludge carried out under He atmosphere was studied by thermogravimetric-mass spectrometric (TG-MS) and thermogravimetric-gas chromatographic-mass spectrometric (TG-GC-MS) analyses. The sludge was thermally degraded with a heating rate of 10°C min^–1 in the 20–1000°C interval; its mass loss is 51.8% up to 600°C and 61.4% up to 1000°C. Gas chromatographic analyses of the gas released during major thermogravimetric events allow the identification of various chemical species. Water, carbon mono- and di-oxide, several hydrocarbons (up to C5, both saturated and unsaturated) were the major detected species. Minor amount of pollutant species, such as cyano-compounds, were also detected. Among the released species hydrocarbons constituted the major fraction (53%), thus suggesting their immediate exploitation as fuel gas. The pyrolysis behaviour of this sample was then compared with other sewage sludge arising from wastewater treatment plants subjected to anaerobic digestion as found in literature data.     

Characterization of the different fractions obtained from the pyrolysis of rope industry waste

A study of the possibilities of pyrolysis for recovering wastes of the rope's industry has been carried out. The pyrolysis of this lignocellulosic residue started at 250 °C, with the main region of decomposition occurring at temperatures between 300 and 350 °C. As the reaction temperature increased, the yields of pyrolyzed gas and oil increased, yielding 22 wt.% of a carbonaceous residue, 50 wt.% tars and a gas fraction at 800 °C. The chemical composition and textural characterization of the chars obtained at various temperatures confirmed that even if most decomposition occurs at 400 °C, there are some pyrolytic reactions still going on above 550 °C. The different pyrolysis fractions were analyzed by GC–MS; the produced oil was rich in hydrocarbons and alcohols. On the other hand, the gas fraction is mainly composed of CO₂, CO and CH₄. Finally, the carbonaceous solid residue (char) displayed porous features, with a more developed porous structure as the pyrolysis temperature increased.     

DSC and thermal stability investigation of novel poly(ester-ether) glycols and poly(ester-ether)urethanes

Mannitol and sorbitol are widely used in the pharmaceutical and food industry. There are some technological procedures such as spray-drying, freeze-drying, tablet compression, during which there is a possibility of heat effect. The purpose of this work was to study the thermal properties of sorbitol, mannitol and their mixtures. Furthermore, these materials and their tablet pressing were studied after melting and solidification. The results of the study prove that the use of sorbitol or mannitol alone is disadvantageous in melt technology. The use of mannitol is limited because of its high melting point (165°C) and the polymorph transition after melting. Sorbitol (melting point: 96.8°C) vitrifies from melt, therefore it is hard to handle during further processing. The melting point of the eutectic mixture (1.8% mannitol and 98.2% sorbitol) was 93.6°C. This mixture was unsuited for pressing because of its glassy property. Our results showed that the most favourable composition was the mixture of 30% mannitol and 70% sorbitol (melting point: 131.8°C) for tablet formulation. This mixture can be recommended for the formulation of such lozenge and hard candy tablets, where the active ingredient decomposes at higher temperature (>131.8°C). This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation,characterization, and properties of fluorene‐containing benzoxazine and its corresponding cross‐linked polymer

A benzoxazine compound (FDP‐FBz), which possesses a fluorene group and two terminal furan groups, and its corresponding cross‐linked polymer (CR‐FDP‐FBz) have been prepared using 4,4′‐(9‐fluorenylidene)diphenol (FDP), furfurylamine, and formaldehyde as precursors. The chemical structure of FDP‐FBz has been characterized with Fourier‐transform infrared and ¹H nuclear magnetic resonance spectroscopies. FDP‐FBz displays a melting point at about 173 °C and a processing window of 52 °C as well as good solubility in common organic solvents. As a result, FDP‐FBz can be fabricated in both molten and solution processes. Under an excitation at 365 nm, FDP‐FBz exhibits a photoluminescent (PL) emission at about 445 nm. The PL intensity of FDP‐FBz is as high as sixfolds of the intensity recorded with FDP. CR‐FDP‐FBz displays a glass transition temperature of 215 °C, a high storage modulus of 3.1 GPa, a 10% weight loss at 384 °C, and a high char yield of 56 wt % (900 °C, in nitrogen). Moreover, CR‐FDP‐FBz has a high refractive index of about 1.65 as a result of incorporating fluorene groups to its structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4020–4026, 2010     

Investigation on structure and morphology of the thermally treated glassy alloy (Fe,Cr)80(P,C,Si)20 by means of ESCA and SEM/EDXA

Metallic glass ribbons of the chemical composition (Fe,Cr)₈₀(P,C,Si)₂₀ have been thermally treated in the region between 530 and 980°C for 72 h. The SEM/EDXA investigations indicate that a phase transformation takes place between 575 and 980°C in a surface layer of 5 μm thickness. Thus, a Cr-rich phase occurs between 760 and 800°C which is converted into an open-pore system between 850 and 900°C. The oxidation process reaches its maximum at 760°C. The ESCA spectra of the material in the “as received” state and of the thermally treated samples indicate that different oxygen species are formed within the analysed surface layer of 10 nm. The oxygen of the original material is incorporated as hydroxyl groups in species such as FeO(OH) and CrO(OH). After thermal treating the hydroxyl content decreases and the oxide content increases. Species of Si exist in the surface layer as SiO_x-like compounds (peak at BE=102.0 eV). A majority phase of transition metal phosphide species is coexisting with oxidised phosphate species.     

Experimental and Theoretical Constraints on pH Measurements with an Iridium Oxide Electrode in Aqueous Fluids from 25 to 175 °C and 25 MPa

In-situ measurement of pH at elevated temperatures and pressures is of major importance for investigating chemical and biochemical systems in extreme environments. Based on the performance of the newly developed IrO _x electrode at 25 °C, we initiated a series of experiments to test the electrode at elevated temperatures (100 to 175 °C) and high pressure (25 MPa). The experiment was carried out in a titanium flow-through reactor. Our results revealed good pH response at 100, 150 and 175 °C, with good Nernstian slopes at 100 and 150 °C. Although a greater-than-Nernstian response was observed at 175 °C, the factors that cause this difference are attributed to the accuracy of calculations of the distribution of aqueous species rather than alteration of the IrO _x surface. A key problem that may limit applications of the IrO _x electrode at elevated temperatures and pressures is the noticeable shift in E° during the 175 °C (25 MPa) experiments and between experiments with similar conditions at 150 °C. The results of tests from 25 °C to elevated temperatures provide highly useful information on the reversibility and functionality of the IrO _x -pH sensor with implications for the suitability of its use under challenging chemical and physical conditions.     

Influence of Calcination on the Properties of Nickel Oxide-Samarium Doped Ceria Carbonate (NiO-SDCC) Composite Anodes

Apart from its composition, the starting powder properties such as particle size potentially affect the triple phase boundary and the electrochemical performance. Calcination process has been identified as one of the factors that influence the particle size of the composite anode powders. This study investigates the correlation between calcination temperature and properties (i.e., chemical, physical, and thermal) of NiO–samarium-doped ceria carbonate (SDCC) composite anodes. NiO–SDCC composite anode powder was prepared with NiO and SDCC through high-energy ball milling. The resultant composite powder was subjected to calcination at various temperatures ranging from 600 °C to 800 °C. Characterizations of the composite anode were performed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy, energy dispersive spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), dilatometry, and porosity measurements. The composite anodes exhibited good chemical compatibility during XRD after calcination and sintering. The FTIR result verified the existence of carbonates in all the composite anodes. The increment in calcination temperature from 600 °C to 800 °C resulted in the growth of nanoscale particles, as evidenced by the FESEM micrographs and crystallite size. Nonetheless, the porosity obtained remained within the acceptable range for a good anodic reaction (20% to 40%). The TGA results showed gradual mass loss in the range of 400 °C to 600 °C (within the low-temperature solid oxide fuel cell region). The composite anodes calcined at 600 °C and 700 °C revealed a good thermal expansion coefficient that matches that of the SDCC electrolyte.     

Mechanism of thermal degradation of urea-formaldehyde polycondensates

The thermal degradation to 500°C of urea-formaldehyde polycondensate occurs in four successive steps. In each step, partial volatilisation takes place while the polymer undergoes chemical modification to give progressively more stable structures.Below 200°C methylene ether bridges are transformed into methylene bridges and branching and crosslinking reactions occur with maximum rates at 125°C and 165°C, respectively. Above 200°C radicals formed by chain scission induce the formation of cyclic structures in the polymer which undergoes extensive fragmentation above 300°C. Water, formaldehyde, carbon monoxide and dioxide, methane, ammonia, monomethylamine and trimethylamine are the gaseous products evolved.By combining data on the chemical modifications and gases evolved in each step, reaction mechanisms are proposed.     

Accelerating rate calorimeter studies of water-induced thermal hazards of fireworks tip mixture

The objective of this article is to generate thermal decomposition data on fireworks tip mixture, a mixture used to coat the tip of fireworks, for easy ignition. This mixture has reportedly involved in triggering many accidents in fireworks industry. Different quantities of water were added to the mixture and its thermal characteristics were studied. Differential scanning calorimeter was used for screening tests and accelerating rate calorimeter was used for detailed studies in adiabatic and isothermal modes. The self-heat rate data obtained showed onset temperature for different quantity of water, at a range of 80–170 °C. The mixture with 40 % water wt/wt had onset at 80 °C in adiabatic mode. The same mixture on isoaging at 40 °C exhibited exothermic characteristics with a substantial rise in system pressure (57 bar). The heats of exothermic decomposition and Arrhenius kinetics were also computed.     

Decomposition of organic hydroperoxides on cation exchangers XV. The kinetics of the decomposition process of p-isopropylcumene hydroperoxide on a catalyst of montmorillonite type

The decomposition of p-isopropylcumene hydroperoxide on a catalyst of montmorillonite type containing Sn²⁺ ions, Sn²⁺-K10 showed first order kinetics in the range of 45-55°C. The activation energy, the enthalpy of activation, the entropy as well as the Gibbs free energy of activation were calculated for the investigated temperature region. Acetone and p-isopropylphenol were produced by this chemical decomposition; both compounds are important intermediates in the chemical industry. This revised version was published online in June 2006 with corrections to the Cover Date.     

Total Soluble Solids from Banana: Evaluation and Optimization of Extraction Parameters

Banana, an important component in the diet of the global population, is one of the most consumed fruits in the world. This fruit is also very favorable to industry processes (e.g., fermented beverages) due to its rich content on soluble solids and minerals, with low acidity. The main objective of this work was to evaluate the influence of factors such as banana weight and extraction time during a hot aqueous extraction process on the total soluble solids content of banana. The extract is to be used by the food and beverage industries. The experiments were performed with 105 mL of water, considering the moisture of the ripe banana (65%). Total sugar concentrations were obtained in a beer analyzer and the result expressed in degrees Plato (°P, which is the weight of the extract or the sugar equivalent in 100 g solution at 20 °C), aiming at facilitating the use of these results by the beverage industries. After previous studies of characterization of the fruit and of ripening performance, a 2² full-factorial star design was carried out, and a model was developed to describe the behavior of the dependent variable (total soluble solids) as a function of the factors (banana weight and extraction time), indicating as optimum conditions for extraction 38.5 g of banana at 39.7 min.     

Non-isothermal thermogravimetric pyrolysis kinetics of waste petroleum refinery sludge by isoconversional approach

Pyrolysis of petroleum refinery sludge has received global acclamation as a clean conversion technique for providing solution of sludge disposal as well as efficient resource utilization. This communication reports the kinetics study of pyrolysis of petroleum refinery sludge. Experiments were carried out by means of thermogravimetric analysis at different heating rates of 5, 10 and 20°C min⁻¹. The pyrolytic reaction is significant in the temperature range of 200–350°C and analysis and evaluation of kinetic parameters is done in the 100–500°C region of non-isothermal TG curves obtained in nitrogen atmosphere. The activation energy is calculated by iso-conversional method, then other kinetic parameters are determined by considering single reaction and two reaction global kinetic model. Two-reaction model is found to fit satisfactorily the experimental results.     

Plasma chemical vapor deposition of TiN

Experiments indicate that the temperature in chemical vapor deposition (CVD) of TiN can be decreased from about 1000°C in conventional CVD to about 500°C by the application of a D.C. nonequilibrium plasma. The hardness of the TiN film is greater than 2000 kg/mm² (Vickers). The effect of pressure, ratio of gas mixture, and discharge parameters on the film deposition rate, its hardness, and microstructures has been studied.     

Effect of calcination temperature on structure and characteristics of calcium oxide powder derived from marine shell waste

Marine fishery wastes such as bivalve shells, crab shells and cuttlebone are rich in calcium. Calcium carbonate derived from these materials can be transformed into calcium oxide by calcination, which is used in a wide variety of applications (e.g., biomaterials for bone and teeth implants and drugs). In this study we analyze the effects of calcination temperatures (550 °C, 700 °C and 900 °C) on characteristics and elemental composition of calcium oxide derived from shells of four marine species collected in Thailand: oyster (Saccostrea cucullata), green mussel (Perna viridis), blue swimming crab (Portunus pelagicus), and cuttlefish (Sepia brevimana). The XRD patterns indicated the complete transformation of calcium carbonate into calcium oxide, observed by the changes of diffraction angles at 900 °C for all calcined samples, except cuttlebone, which was calcined successfully at 700 °C. Likewise, the FT-IR results revealed changes of functional groups at the same calcination temperatures. In addition, ICP-OES showed the effects of calcination temperature on elemental contents: major elements (Ca, P and K) increased in all samples, and some minor elements increased in blue swimming crab shell (Zn and Cu) and oyster shell (Fe) as a result of increasing the calcination temperature. This study demonstrates the optimum calcination temperature of calcium oxide production from four types of marine wastes that might be benefit for the chemical compound production industry.     

Effect of Heating Strategy on Power Consumption and Performance of a Pilot Plant Anaerobic Digester

The effect of heating strategy on power consumption and performance of a pilot plant anaerobic digester treating chicken litter, under thermophilic conditions, has been studied. Heating strategy was evaluated using three different spans (0.2 °C, 0.6 °C, and 1.0 °C) for triggering the temperature control system from target temperature (56.7 °C). The hydraulic retention time in the pilot plant digester was in the range of 32 to 37 days, varying the total solids concentration fed from 5% to 6%. The results showed that under the experimental conditions, heating was the most energy-demanding process with 95.5% of the energy used. Increments up to 7.5% and 3.8%, respectively, on mechanical and heating power consumption, were observed as the span, for triggering the temperature control system from target temperature, was increased. Under the experimental conditions studied here, an increment of 30.6% on the global biodigester performance index was observed when a span of 1.0 °C was compared to the one of 0.2 °C.     

Full physicochemical characterization of malic acid: Emphasis in the potential as food ingredient and application in pectin gels

Malic acid, a carboxylic acid most found in fruits, is a smooth taste substance used as flavoring and preservative agent in foods, although not as used as citric acid. There are no studies focusing in quantitative results or investigations on its physicochemical properties, useful to the food industry, or even the confirmation of its calcium chelating, buffer texturizer and antioxidant alleged properties. Thus, the aim of this work was the assessment of most physicochemical properties of malic acid, solid and in solution, that could be useful to the food industry understand its real potential. The following analyses were carried out: melting point; structure (NMR, XRD, FTIR and SEM/EDS); TGA/DTG; solubility, hygroscopicity; antioxidant activity, iron chelating and antibacterial activities and stability of pectin gels. The melting temperature found was 129.71 °C. TGA/DTG exhibited first loss of mass around 140 °C. In the temperature range of 10 to 55 °C, it exhibited a high solubility in water, from 48.12 to 61.49 (100w), respectively. The tested bacteria, related to food spoilage, were inhibited by DL-malic acid 10% or higher. Chelating and antioxidant activities showed expressive results even in 1% solution. Pectin gels with malic acid had stronger structure and less syneresis than citric acid gels. In addition, calcium chelating, buffer texturizer and antioxidant properties were confirmed. Thus, malic acid has potential to be applied in a wide variety of food products as fortified beverages, frozen and refrigerated items, oils, pectin gels, hard and soft candies, and biofilms, due to all the characteristics quantified.