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Effect of calcination temperature on Ni/MgAl 2 O 4 catalyst was investigated in order to evaluate changes on structural and catalytic properties for catalytic partial oxidation of methane. The catalysts were calcined at different temperatures after impregnation of nickel salt solution on MgAl 2 O 4 support. The prepared catalysts showed nearly 89% CH 4 conversion and 99% H 2 selectivity under the flow of 157,000 (l kg −1 h −1 ) with the ratio of CH 4 /air = 0.44 at 1 atm and 800 °C. However, turnover frequency values of the catalysts were between 8.2 and 42.3 s −1 and increased according to Ni particle size. Lewis basicity/acidity ratio increased from 2.14 to 4.46 with increasing calcination temperature. It was found that coking rate on the catalysts depends on Ni particle size and surface basicity/acidity. The experimental results showed that calcination temperature and time have a significant influence on both structural and catalytic properties of the catalysts that show strong metal oxide support interaction. It could be claimed that high calcination temperatures could be beneficial to obtain highly active, selective and stable Ni/MgAl 2 O 4 catalysts, which possess strong metal oxide support interaction, by maintaining Ni dispersion high after reduction, increasing surface basicity and enhancing the stability of Ni particles against sintering.

SmxCa0.2−xCe0.8Oy materials are synthesized by changing mol ratios of the composition as x = 0, 0.05, 0.1, 0.15 and 0.2, respectively, with a fast and facile cellulose templating method for the first time. Microstructures of the calcined and sintered samples are characterized by XRD and SEM-EDX. Density measurements are actualized by using Archimedes method. The electrical conductivity of the samples is obtained from two-probe impedance spectroscopy. Maximum solubility limit of CaO in CeO2 is found to be 9.4 mol% from the XRD results. Incorporation of CaO slightly increases the sinterability of the samples. It is observed that Sm+3 expands the CeO2 lattice more than Ca+2. 10 mol% CaO incorporated sample show the highest total conductivity with the value of 0.032 S cm−1 at 800 °C. Obtained results show that Sm0.1Ca0.1Ce0.8Oy can be an excellent candidate for intermediate temperature solid oxide fuel cell applications due to its lower cost and higher performance compared to Sm0.2Ce0.8Oy at 800 °C. Additionally, cellulose templating method can be used as an effective method in order to prepare mixed oxide structures since the performances of the samples are higher than the samples which are prepared by more complex or costly hydrothermal and co-precipitation methods in literature.

The catalytic partial oxidation of methane (CPOM) was studied on Ni based catalysts. Catalysts were prepared by wet impregnation method and characterized by using AAS, BET, XRD, HRTEM, TPR, TPO, Raman Spectroscopy and TPSR techniques. The prepared catalysts showed nearly 95% CH4 conversion and nearly 96% H2 selectivity under the flow of 157,500 (L kg−1 h−1) with the ratio of CH4/O2 = 2 by using air as an oxidant at 1 atm and 800 °C. Support basicity greatly influenced the H2/CO ratio and carbon deposition. It was found that the lowest carbon deposition occurred on Ni impregnated MgO catalyst. Considering the results, it was found that Ni/MgO catalyst with 10% Ni content would be the best catalyst amongst Ni/Al2O3, Ni/MgO/Al2O3, Ni/MgAl2O4 and Ni/Sorbacid for the CPOM only under more reductive conditions. Under optimum conditions, Ni/MgO showed poor performance and therefore Ni/Sorbacid would be the ideal catalyst because of its greater carbon resistance than the other catalysts.

The paper is concerned with the formation of Layer-by-Layer (LbL) self-assembly of highly charged polyvinyl sulfate potassium salt (PVS) and polyallylamine hydrochloride (PAH) on Nafion membrane to obtain the multilayered composite membranes with both high proton conductivity and methanol blocking properties. Also, the influences of the salt addition to the polyelectrolyte solutions on membrane selectivity (proton conductivity/methanol permeability) are discussed in terms of controlled layer thickness and charge density. The deposition of the self-assembly of PAH/PVS is confirmed by SEM analysis and it is observed that the polyelectrolyte layers growth on each side of Nafion membrane regularly. (PAH/PVS) 10 –Na + and (PAH/PVS) 10 –H + with 1.0 M NaCl provide 55.1 and 43.0% reduction in lower methanol permittivity in comparison to pristine Nafion, respectively, while the proton conductivities are 12.4 and 78.3 mS cm −1 . Promisingly, it is found that the membrane selectivity values ( Φ ) of all multilayered composite membranes in H + form are much higher than those of Na + form and perfluorosulfonated ionomers reported in the literature. These encouraging results indicate that composite membranes having both superior proton conductivity and improved methanol barrier properties can be prepared from highly charged polyelectrolytes including salt for fuel cell applications.

Asphaltenes are a major concern in production operations, due to their role in conversion of vacuum residues by processes such as coking, catalytic cracking and hydroconversion. Six Turkish asphaltenes were characterized by elemental content, proton NMR, carbon NMR, GPC, DSC. Differential scanning calorimetry (DSC) provides parameters for comparing the glass transition temperatures, endothermic behavior of asphaltene and a hypothetical melting temperature of the asphaltenes which is within the range of the pyrolysis temperature of asphaltenes. The glass transition temperatures points (Tg) of asphaltenes were determined using DSC. Hypothetical melting point temperature (Tm) of the asphaltenes was also calculated. Among all the asphaltenes tested, Bati Raman showed much higher glass transition temperatures than the others. � 2007 Elsevier Ltd. All rights reserved.