12-tungstophosphoric and 12-tungstosilicicacid supported onto hydrous zirconia for liquid phase tert-butylation of m-cresol

Supported 12-tungstophosphoricacid (12-TPA) and 12-tunstosilicicacid (12-TSA) were used as heterogeneous catalysts for liquid-phase tert-butylation of m-cresol, an industrial important reaction. Alkylation reactions have been carried out with supported 12-TPA by varying different parameters such as % loading of 12-tungstophosphoricacid onto support, mole ratio of alcohol to m-cresol, reaction temperature, amount of the catalyst, reaction time and calcination temperature to optimize the conditions. To see the effect of the acidity on the reaction, the same reaction was studied over supported 12-TSA. Both the catalysts give 100% selectivity for o-isomer with different % conversion. The difference in catalyst performance of both the catalyst was correlated with the value of total acidity as well as Bronsted acidity.     

Mesoporous molecular sieves: alkylation of anisole using tert-butylalcohol

Mesoporous aluninosilicate Al-MCM-41 molecular sieves with Si/Al ratios 25, 50, 75 and 100 have been synthesized under hydrothermal condition and these materials were characterized by XRD, FTIR, BET and pyridine adsorption techniques. The catalytic performance was examined in the vapor phase tert-butylation of anisole with tert-butanol at the temperatures between 150 and 250 °C under atmospheric pressure. The results indicate that Al-MCM-41 (25) was found to be more active than its relatives. The major products are found to be 4-tert-butyl anisole (4-TBA), 2-tert-butyl anisole (2-TBA) and 2,4 di-tert-butyl-anisole (2,4-DTBA). Maximum conversion of anisole is observed at 175 °C and decreased thereafter with increasing temperature. The influence of molar feed ratio, influence of temperature, WHSV and time on stream on the selectivity of products was investigated and the results are discussed.     

deNO x reduction by methanol over Co/alumina

The temperature window of NO _x consumption lies between 140 and 500 °C. The 0.5 wt%Co/Al₂O₃ catalyst exhibits a total consumption of NO _x between 300 and 350 °C at a space velocity of 50 000 h⁻¹. The presence of acetonitrile and methylnitrite can explain the difference between N₂ formation and NO_x consumption at T< 400 °C. The Co²⁺, in octahedral site, has been shown to coordinate two NO molecules.     

Biotransformation of 12-hydroxyoctadecanoic acid to 12-hydroxyoctadecanamide by Bacillus cereus 50

A new microbial isolate (Bacillus cereus 50) transformed 12-hydroxyoctadecanoic acid to 12-hydroxyoctadecanamide when grown aerobically in 1% yeast extract medium at 30°C, shaken at 250 rpm for 2 to 5 d. The compound was purified by thin-layer chromatography and characterized by infrared, gas chromatography, mass spectrometry, and nuclear magnetic resonance. The yields of 12-hydroxyoctadecanamide were 9.1 and 21.5% after 2 and 5 d, respectively.     

(2S,12Z)-2-Acetoxy-12-heptadecene: Major Sex Pheromone Component of Pistachio Twig Borer, Kermania pistaciella

The sex pheromone of the pistachio twig borer, Kermania pistaciella (Lepidoptera: Oinophilidae), one of the most important insect pests of pistachio, Pistacia vera, in Turkey and Iran, was identified. In gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses of pheromone gland extracts of female K. pistaciella from Turkey, (2S,12Z)-2-acetoxy-12-heptadecene was identified as the major candidate pheromone component. In field experiments in Turkey, lures containing synthetic (2S,12Z)-2-acetoxy-12-heptadecene attracted large numbers of male moths. Its attractiveness was significantly reduced by the presence of the R-enantiomer or of either enantiomer of the corresponding alcohol. (2S,12Z)-2-Acetoxy-12-heptadecene is the first pheromone component identified in the Oinophilidae and the first secondary acetate pheromone component identified in the Lepidoptera. An erratum to this article can be found at     

Steam reforming of methanol using Cu-ZnO catalysts supported on nanoparticle alumina

Methanol steam reforming was studied over several catalysts made by deposition of copper and zinc precursors onto nanoparticle alumina. The results were compared to those of a commercially available copper, zinc oxide and alumina catalyst. Temperature programmed reduction, BET surface area measurements, and N₂O decomposition were used to characterize the catalyst surfaces. XRD was used to study the bulk structure of the catalysts, and XPS was used to determine the chemical states of the surface species. The nanoparticle-supported catalysts achieved similar conversions as the commercial reference catalyst but at slightly higher temperatures. However, the nanoparticle-supported catalysts also exhibited a significantly lower CO selectivity at a given temperature and space time than the reference catalyst. Furthermore, the turnover frequencies of the nanoparticle-supported catalysts were higher than that of the commercial catalyst, which means that the activity of the surface copper is higher. It was determined that high alumina concentrations ultimately decrease catalytic activity as well as promote undesirable CH₂O formation. The lower catalytic activity may be due to strong Cu-Al₂O₃ interactions, which result in Cu species which are not easily reduced. Furthermore, the acidity of the alumina support appears to promote CH₂O formation, which at low Cu concentrations is not reformed to CO₂ and H₂. The CO levels present in this study are above what can be explained by the reverse water-gas-shift (WGS) reaction. While coking is not a significant deactivation pathway, migration of ZnO to the surface of the catalyst (or of Cu to the bulk of the catalyst) does explain the permanent loss of catalytic activity. Cu₂O is present on the spent nanoparticle catalysts and it is likely that the Cu⁺/Cu⁰ ratio is of importance both for the catalytic activity and the CO selectivity.     

氧化铝负载Co-Mo双金属氧化物的共沉淀制备

采用双溶剂体系(硝酸铝和硝酸钴的乙醇溶液与钼酸铵的碳酸铵水溶液)共沉淀制备了氧化铝负载Co-Mo双金属氧化物。研究了双溶剂体系中乙醇和水的体积比对共沉淀的影响,考察了老化时间对氧化物结构参数的影响,研究了焙烧温度对氧化物还原性能的影响。结果表明:乙醇和水体积比对钼酸根离子的沉淀有重要影响,为了保证钼酸根离子的完全沉淀,乙醇的体积要随着MoO3负载量的增加而提高;随着老化时间的增加,氧化物的比表面积先增加后下降,6 h老化的样品具有最大的比表面积;低温焙烧制得的氧化物较容易还原。     

Wet oxidation of wastewater containing hydrocarbons by novel supported Pd catalysts

Pd catalysts supported on TiO₂, ZrO₂, ZSM-5, MCM-41 and activated carbon were used in catalytic wet oxidation of hydrocarbons such as phenol, m-cresol and m-xylene. It was found that the Pd/TiO₂ catalyst was highly effective in the wet oxidation of hydrocarbon. The activities of catalysts with various hydrocarbon species, catalyst support, oxidation state of catalyst performed in a 3-phase slurry reactor show that reaction on Pd surface is more favorable than that in aqueous phase and that the active site is oxidized Pd in catalytic wet air oxidation of hydrocarbons. Based on the experimental results, a plausible reaction mechanism of wet oxidation of hydrocarbons catalyzed over Pd/TiO₂ catalyst was proposed. This catalyst is superior to other oxide catalysts because it suppressed the formation of hardly-degradable organic intermediates and polymer.     

Joining of alumina and steel by a laser supported brazing process

A laser supported method to join ceramic materials with metals has been studied. Using a CO₂-laser and an active braze filler material, Al₂O₃-ceramics have been brazed to steel. The microstructure of the interface has been examined and also the mechanical strength of the brazed joint using bending tests. Typical processing times are of the order of several minutes, which is faster than furnace brazing. The results of the mechanical tests show that the failure of the brazed metal–ceramic joint occurs within the ceramic close to the interface between the braze filler metal and the ceramic part. Thermally induced stresses may lead to cracks within the ceramic, which initiates the failure under mechanical loading. The typical bending strength varies between 40 and 80 MPa with a Weibull modulus ranging from 4.3 to 6.1.     

Removal of fluoride from drinking water by adsorption onto alum-impregnated activated alumina

The ability of the alum-impregnated activated alumina (AIAA) for removal of fluoride from water through adsorption has been investigated in the present study. All the experiments are carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–8), adsorbent dose (0.5–16 g/l), initial fluoride concentration (1–35 mg/l) has been investigated to determine the adsorption capacity of AIAA. The adsorbent dose and isotherm data are correlated to the Bradley equation. The efficacy of AIAA to remove fluoride from water is found to be 99% at pH 6.5, contact time for 3 h, dose of 8 g/l, when 20 mg/l of fluoride is present in 50 ml of water. Energy-dispersive analysis of X-ray shows that the uptake of fluoride at the AIAA/water interface is due to only surface precipitation. The desorption study reveals that this adsorbent can be regenerated following a simple base–acid rinsing procedure, however, again impregnation of the regenerated adsorbent (rinsed residue) is needed for further defluoridation process.     

Application of Cs salt of 12-tungstophosphoric acid supported on SBA-15 mesoporous silica in NO x storage

Cs salt of 12-tungstophosphoric acid (HPW) was deposited simultaneously at the external surface of the SBA-15 silica microcrystals and inside its mesoporous channels at loading of 60 wt% and Cs/W ratio in the range between 0.9 and 2, followed by impregnation of 1 wt% Pt. The performance of the Pt/CsHPW/SBA-15 composite materials was tested in the NO _x storage. The optimal NO _x storage capacity and efficiency were achieved at Cs/W of 1.5. The dispersion of CsHPW on SBA-15 led to a significant decrease of its crystal size (5–13 nm) compared with bulk HPW and HPW supported on titania (28–29 nm). Pt/CsHPW/SBA-15 displayed lower NO _x absorption capacity but much higher absorption and desorption efficiency than the reference Pt/HPW and Pt/HPW/TiO₂ materials. Consequently, Pt/CsHPW/SBA-15 displayed a better performance in short lean (2 min)—rich (1 min) absorption-desorption cycles. The novel Pt/CsHPW/SBA-15 nanocomposites presents the basis for improved storage material for NO _x removal from lean exhaust gases in highly dynamic aftertreatment technologies.     

Selective reduction of NO X in diesel exhaust with hydrocarbons over alumina in NEDC conditions

The selective catalytic reduction (SCR) of NO _X assisted by hydrocarbons was investigated on alumina in New European Driving Cycle (NEDC) conditions. The alumina efficiency towards the deNO _X process was shown in the temperature range 200–400 °C involving a three-catalytic cycle mechanism. However, many parameters influence the catalytic activity: temperature, HC/NO _X ratio and GHSV.     

Separation of l-valine by anionic carrier-mediated transport in a supported liquid membrane

An anionic carrier-mediated separation of L-valine from the dilute aqueous solution was studied with a liquid membrane, constituted by a solution of D2EHPA (Di-2-Ethyl Hexyl Phosphoric Acid) in 1-decanol and supported by a hydrophobic microporous membrane. The equilibrium and transport rate data are reported in terms of distribution coefficients and mass transfer coefficients under the varying conditions of feed phase pH and carrier concentration. The experimental results obtained are analyzed to confirm the mechanism of the complex formation between carrier and L-valine and to describe the transport rate of L-valine through the supported liquid membrane by an appropriate theoretical model. The selectivity and the stability of the supported liquid membrane under study were also evaluated to ensure its potential application as a commercial down-stream process.     

Synthesis of Ethyl 5 Z ,9 Z ,12 Z -octadecatrienoate (ethyl pinolenate) and Methyl 12 Z ,15 Z -octadecadienoate

Pinolenic acid (5Z,9Z,12Z-octadecatrienoic acid, 1a), one of the most abundant trienoic fatty acids in nature, is very difficult to obtain in quantity in a pure state from the highly complex mixture of unsaturated tall oil fatty acids. For this reason its chemistry has been little studied when compared to linolenic or linoleic acids. A simple synthesis of esters of 1a and of 12Z,15Z-octadecadienoic acid 3 using the one pot double Wittig procedure is described here. The products of double Wittig reactions were purified by argentation chromatography, and their structural purity was established by ¹H-, ¹³C-NMR and 2D-NMR spectroscopies.

Study of neutral lipids ofLupinus mutabilis meal and isolates

Two types of protein isolates have been obtained from defattedLupinus mutabilis meal. The isolates, MA and MB, were obtained by alkaline extraction with 0.2% NaOH and 0.25% sodium bisulfite, respectively, followed by precipitation at the isoelectric point (pH 4.8). Total associated lipids were extracted with 86% ethanol. Neutral lipids were separated in a Florisil column. The lipids in the isolates were similar to those found in the original meal. The following types of compounds were separated, identified, and quantitated: hydrocarbons, waxes, methyl esters, triacylglycerols, free fatty acids, diacylglycerols, and free sterols.     

铝基铜干法烟气脱硫剂制备及脱硫再生实验

采用浸渍法制备了铝基铜脱硫剂,考察了制备过程中浸渍液浓度对脱硫剂脱硫性能的影响,同时对制得的脱硫剂进行了循环烟气脱硫-再生实验,分析了脱硫剂的表面微观结构在脱硫和再生过程中的变化.实验和分析表明,制得的铝基铜脱硫剂具有较高的脱硫效率,使用该脱硫剂进行循环烟气脱硫的性能是稳定的.     

12-Tungstophosphoric acid immobilized on modified macroporous phenol-furfural sulfonic acid resin for tert-butylation of p-cresol.

12-Tungstophosphoric acid (HPW) had been immobilized on phenol-furfural sulfonic acid resin (PFuSR) using γ-aminopropyltriethoxy silane (KH). FT-IR spectra indicate that the immobilized HPW on KH modified PFuSR (PFuSR-KH) keeps its Keggin structure and IR subtraction spectra confirm the immobilization of HPW on PFuSRKH through the interaction between amino groups of KH and bridge oxygen atom of W₃O₁₃. XRD patterns of the HPW illustrate that its second-order structure is changed greatly after being immobilized. The immobilized HPW on KH-modified PFuSR not only maintains its selectivity but also possesses high acidic activity in catalyzing t-butylation of p-cresol with t-butanol, though the by-product water hindered the reaction. The PFuSR-KH-immobilized HPW loses only half of its activity after being reused five times, while the PFuSR-supported one has no catalytic activity in the second run.     

Partial oxidation of methanol on TiO2- supported 12-molybdophosphate catalysts

Steam reforming of ethanol, C₂H₅OH+H₂O→2CO+4H₂, was carried out over Co/Al₂O₃, Co/SiO₂, Co/MgO, Co/ZrO₂ and Co/C. The properties of the Co catalysts were greatly affected by the supports. Co/Al₂O₃ exhibited the highest selectivity for steam reforming of ethanol by suppression of methanation of CO and decomposition of ethanol. This revised version was published online in July 2006 with corrections to the Cover Date.     

H3PW12O40 Supported on AlMCM-41 molecular sieves: An effectual catalyst for t-butylation of anisole

Mesoporous AlMCM-41 (Si/Al = 25) molecular sieves was synthesized and impregnated with different loadings (10, 20 and 30 wt% H₃PW₁₂O₄₀) of phosphotungstic acid. Their catalytic performance was examined in the vapour phase alkylation of anisole with tert-butanol. The major products were found to be 2-tert-butyl anisole (2-TBA), 4-tert-butyl anisole (4-TBA), 2,4-di-tert-butyl anisole (2,4-DTBA). 4-TBA was the major product formed with high selectivity. The influence of temperature, feed ratio, WHSV was studied and the results are discussed.