Size distribution nitrogen content

The Au contents were analyzed by ICP. UV-vis diftuse reflectance spectroscopy (DRS) was performed on a Varian Cary IE UV-VIS Spectrometer. X-ray diftfaction patterns were coUected using a Rigaku dififtactometer with Cu radiation. The surface area and the pore size distribution was obtained using nitrogen adsorption. 

The evolution of fuel nitrogen is not a function of total nitrogen content of a fuel only, but is strongly dependent upon the distribution of nitrogenous compounds in the fuel. The rate of fuel nitrogen evolution is not completely determined by the composition of the fuel, but may be influenced by the rate of vaporization, which is determined by droplet size and ambient temperature. 

Reaction of dissolved gases in clouds occurs by the sequence gas-phase diffusion, interfacial mass transport, and concurrent aqueous-phase diffusion and reaction. Information required for evaluation of rates of such reactions includes fundamental data such as equilibrium constants, gas solubilities, kinetic rate laws, including dependence on pH and catalysts or inhibitors, diffusion coefficients, and mass-accommodation coefficients, and situational data such as pH and concentrations of reagents and other species influencing reaction rates, liquid-water content, drop size distribution, insolation, temperature, etc. Rate evaluations indicate that aqueous-phase oxidation of S(IV) by H2O2 and O3 can be important for representative conditions. No important aqueous-phase reactions of nitrogen species have been identified. Examination of microscale mass-transport rates indicates that mass transport only rarely limits the rate of in-cloud reaction for representative conditions. Field measurements and studies of reaction kinetics in authentic precipitation samples are consistent with rate evaluations. 

The preparation of CoMo/AAP catalysts has been reported in ref, 5. The metal contents of the catalysts were determined by ICP-AKS-The specific surface areas of the catalysts were measured by the traditional BET method with nitrogen adsorption. The pore size distributions were measured by inecury penetration method,... 

The textural nature of the titania and TiCex were characterised by nitrogen ad/desorption isotherms. The specific surface areas are presented in Table la. None of the materials were found to be microporous from t-plot analyses of the adsorption isotherms. From the desorption curves, the mesopore size distribution was calculated using the BJH method. All of the samples had bimodal mesopore size distributions. The volumes of the narrow and wide mesopores, presented in Table lb), were calculated from the minima between the two distributions. These results indicated, that as the amount of ceria incorporation rose, the bimodal mesopore size distribution became narrower. For the titania sample the mesopores were centred in diameters of approximately 14 and 17 nm. With ceria incorporation both of these diameters were reduced until at the highest ceria content they were approximately 9 and 15 nm. 

BET surface area measurements were performed using the single point method on a Micromeritics Flow Sorb II 2300 equipment. Vanadium and aluminum contents in the different prepared catalysts were determined by ICP technique. The total nitrogen content in the oxynitride samples was determined using the method described by Guyader et al [9]. Particle size distribution of the samples was determined using a Coulter LSI30 equipment. 

The gold content in catalysts was analyzed by Atomic absorption method and made by the Analytical Center of the CNRS, Lyon, France. The XRD patterns were obtained with a Philips PW 170 diffiactometer, using Cu Ka (1.54178 A) radiation. High resolution transmission electron microscopy (HRTEM) analysis was performed on a Jeol JEM-3010 microscope at 300 kV. Nitrogen adsorption-desorption isotherms and specific surface areas were measured at -196 °C over a wide relative pressure range from 0.01 to 0.995 with a volumetric adsorption analyzer TRISTAR 3000 manufactured by Micromeritics. The pore diameter and the pore size distribution were determined by the Barret-Joyner-Halenda (BJH) method using the adsorption branch of isotherms [15]. 

The resultant materials were characterised by powder X-ray diffraction (XRD) and by nitrogen adsorption at 77K, using the adsorption isotherm to calculate BET surface area, and the desorption isotherm and BJH method to determine the pore size distribution. The concentrations of acid sites were measured by pH titration with standard NaOH solution, following exchange with excess NaCl solution. Water contents were measured by heating to constant weight at 150 C. 

From the pore size distribution examined by nitrogen adsorption it follows that xerogels with a minor content of core structure Q often have no pores or micropores with width less than 2 nm, whereas in gels with a predominating content of tetrafunctional building groups Q mesopores are... 

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