Zirconium titanate synthesis by diethanol amine based sol-gel route

ZrTiO4 powder are synthesized by a modified sol-gel route via bimetallic diethanol amine complex of zirconium and titanium alkoxides. Samples are cured at 140 degrees C and calcined between 500-800 degrees C. Powders are characterized with XRD, TGA, DTA, SEM and TEM methods. The ZrTiO4 powders are obtained at 650 degrees C from the amorphous form. No identified peaks can be attibuted to other phases, namely, zirconia and titania are not observed

Oxidative dehydrogenation of propane over V2O5 and K2O-V2O5 impregnated MgAl2O4 catalysts

V2O5 and K2O-V2O5 impregnated MgAl2O4 catalysts were prepared and tested for the oxidative dehydrogenation of propane. The as-synthesized catalysts were characterized by using the XRD, BET, NH3-TPD, TPR, and XPS methods. The catalytic tests were performed in a fixed bed tubular quartz reactor system between 450 and 550 degrees C. It was observed that the conversion of propane increased but hydrocarbon selectivity decreased with increasing temperature over the V2O5/MgAl2O4 catalysts. The BET surface area values and surface acidities decreased upon potassium addition for the K-V2O5/MgAl2O4 catalysts, which resulted in a drastic drop in the conversion values obtained. The propylene and total hydrocarbon selectivities increased with increasing temperature

Hydrogenation of furfural to furfuryl alcohol over efficient sol-gel nickel-copper/zirconia catalyst

Furfuryl alcohol (FA), a valuable compound from furfural (FF) was synthesized by efficient Ni-Cu/ZrO2 catalysts. The catalysts with varying Ni and Cu loading were developed by sol-gel method and characterized by Brunauer-Emmet-Teller (BET) method, X-ray diffraction, Temperature Programmed Reduction (TPR), X-ray photoelectron spectroscopy techniques. Cu/ZrO2 and Ni/ZrO2 catalysts were also tested to compare the effect of the Ni-Cu/ZrO2 catalyst. Both Ni and Cu showed the synergistic effect on FA formation. The Ni-Cu/ZrO2 catalyst was used for hydrogenation of FF by changing pressure, catalyst loading, temperature and time. A 93% FA yield was achieved over the 7Ni-Cu/ZrO2 catalyst with 0.07 g Ni and 0.1 g Cu/1 g ZrO2 at 200 degrees C for 4 h under 1.5 MPa H-2 pressure. The sol-gel Ni-Cu/ZrO2 catalyst without the use of expensive noble metals is effective on the hydrogenation of FF to FA relatively in mildly reaction pressure. Graphic abstract The Ni-Cu/ZrO2 catalyst was used for hydrogenation of FF by changing pressure, catalyst loading, temperature and time. A 93% FA yield was achieved over the 7Ni-Cu/ZrO2 catalyst with 0.07 g Ni and 0.1 g Cu/1 g ZrO2 at 200 degrees C for 4 h under 1.5 MPa H-2 pressure. The sol-gel Ni-Cu/ZrO2 catalyst without the use of expensive noble metals is effective on the hydrogenation of FF to FA relatively in mildly reaction pressure

An efficient heterogeneous CrOx-Y zeolite catalyst for glucose to HMF conversion in ionic liquids

In this study, CrCI3, H-Y, Cr-Y and calcined CrOx-Y zeolites were studied in the liquid phase heterogeneous catalytic conversion of glucose to HMF in ionic liquids. Characterization of catalysts was done in XPS, XRD and NH3-TPD. Both glucose conversion and HMF yield decreased with the addition of chromium (III) chloride impregnated catalysts in comparison to the homogeneous CrCI3-[BMIM]CI system. High glucose and HMF yields were obtained with heterogeneous calcined CrOx-Y zeolite. Best HMF yield achieved was 52.8%

Thermal-catalytic degradation kinetics of polypropylene over BEA, ZSM-5 and MOR zeolites

In this study, thermal degradation of additive-free polypropylene powder over different type of zeolite catalysts was investigated. BEA, ZSM-5 and MOR with different surface areas, pore structures, acidities and Si/Al molar ratios were used as solid catalysts for degradation of polypropylene (PP). Degradation rate of the PP over zeolites was studied by thermogravimetric analysis (TGA) employing four different heating rates and apparent activation energies of the processes were determined by the Kissinger equation. The catalytic activity of zeolites decreases as BEA > ZSM-5a (Si/Al = 12.5) > ZSM-5b (Si/Al = 25) > MOR depending on pore size and acidity of the catalysts. On the other hand, initial degradation is relatively faster over MOR and BEA than that over both ZSM-5 catalysts depending on the apparent activation energy. It can be concluded that acidity of the catalyst is the most important parameter in determining the activity for polymer degradation process as well as other structural parameters, such as pore structure and size. (c) 2005 Elsevier B.V. All rights reserved

Nafion-Graphene Composite Film Modified Glassy Carbon Electrode for Voltammetric Determination of p-Aminophenol

A Nafion-graphene (Nafion-GR) nanocomposite film modified glassy carbon electrode was fabricated by a simple drop -casting method, and used in the electrochemical detection of p-aminophenol (4-AP). Owing to the large surface area, good conductivity of GR and good affinity of Nafion, the sensor exhibited excellent electrocatalytic activity for the oxidation of 4-AP. The electrochemical behaviors of 4-AP on Nafion/GR film modified glassy carbon electrodes were investigated by cyclic voltammetry and differential pulse voltammetry. A calibration curve is constructed in the same matrix, urine, as the unknown samples to be analyzed. The Nafion-GR film modified electrode was linearly dependent on the 4-AP concentration and the linear analytical curve was obtained in the ranges of 0.5-200-M with differential pulse voltammetry (DPV) and the detection limit was 0.051-M. The Nafion-graphene nanocomposite modified electrode exhibited good reusability than pure graphene modified GCE. This procedure can be used for the determi- nation of p-aminophenol in the presence of its degradation products and paracetamol. Finally, the proposed method was successfully used to determine p-aminophenol in local tap water samples in urine samples and pharmaceutical preparations

Electrochemical Sensing of Acetaminophen on Electrochemically Reduced Graphene Oxide-Nafion Composite Film Modified Electrode

An electrochemical sensor based on graphene-Nafion nanocomposite film for voltammetric determination of acetaminophen (APAP) was presented. A Nafion graphene oxide-modified glassy carbon electrode was fabricated by a simple drop-casting method and then graphene oxide was reduced at the glassy carbon electrode surface by electrochemical method. The resulting electrode [electrochemically reduced graphene oxide (ER-GO)/Nafion glassy carbon electrode (GCE)] was used to determine acetaminophen. The electrochemical behaviors of acetaminophen on Nafion/ER-GO modified glassy carbon electrodes (GCEs) were investigated by cyclic voltammetry and square-wave voltammetry. The results obtained that the Nafion/ER-GO/GC modified electrode was exhibited excellent electrochemical activity on the oxidation of APAP. The calibration curve for APAP was shown two linear segments: the first linear segment increases from 0.4 to 1.0 and second linear segment increases up to 10 mu M. The detection limit was determined as 0,025 mu M (2.5x10(-8) mol L-1) using SWV. Finally, the proposed method was successfully used to determine APAP in pharmaceutical preparations and urine samples

Preparation of Yttria-Stabilized Zirconia by the Reverse Microemulsion Method and the Effect of Sc and Ce Doping on Microstructure and Ionic Conductivity for Solid Oxide Fuel Cell Applications

In this study, 8 mol% yttria-stabilized zirconia (8YSZ), ceria-, and scandia-doped YSZ powders were synthesized by the reverse microemulsion method. The powders were calcined at 1000 degrees C and sintered at 1450 degrees C. The crystalline properties and microstructure of the samples were characterized by X-ray diffraction and SEM methods, respectively. Oxygen ionic conductivities of the samples were measured by electrochemical impedance spectroscopy in the temperature range 250-375 degrees C. Grain interior and grain boundary resistivities were also calculated. Particle sizes of YSZ and Sc-doped YSZ were found to be < 100 nm, while that of Ce-doped YSZ was 120-150 nm. Approximately 1 mu m grains were observed after sintering of YSZ at 1450 degrees C. Particularly, the grain boundary and also the grain interior resistivities decreased with 3% scandia-doped YSZ. It was observed that the total conductivity of 3YSZ was higher than that of 3% ceria-doped YSZ

Square-wave stripping voltammetric determination of caffeic acid on electrochemically reduced graphene oxide-Nafion composite film

An electrochemical sensor composed of Nafion-graphene nanocomposite film for the voltammetric determination of caffeic acid (CA) was studied. A Nafion graphene oxide-modified glassy carbon electrode was fabricated by a simple drop-casting method and then graphene oxide was electrochemically reduced over the glassy carbon electrode. The electrochemical analysis method was based on the adsorption of caffeic acid on Nafion/ER-GO/GCE and then the oxidation of CA during the stripping step. The resulting electrode showed an excellent electrocatalytical response to the oxidation of caffeic acid (CA). The electrochemistry of caffeic acid on Nafion/ER-GO modified glassy carbon electrodes (GCEs) were studied by cyclic voltammetry and square-wave adsorption stripping voltammetry (SW-AdSV). At optimized test conditions, the calibration curve for CA showed two linear segments: the first linear segment increased from 0.1 to 1.5 and second linear segment increased up to 10 mu M. The detection limit was determined as 9.1 x 10(-8) mol L-1 using SW-AdSV. Finally, the proposed method was successfully used to determine CA in white wine samples. (C) 2013 Elsevier B.V. All rights reserved