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Ni-containing catalysts are investigated under reaction conditions for two different cases, during sulfidation, with Ni-Mo based catalysts, and during ammoxidation reaction, with the Ni-Nb catalysts. It is shown how Raman spectroscopy can follow some of the transformations of these catalysts upon different treatments. For the NiMo/Al(2)O(3)-SiO(2) system it was possible to identify some of the sulfided Mo species formed during the sulfidation of the oxide precursors, while for the bulk Ni-Nb oxide catalysts the simultaneous reaction-Raman results strongly suggest that the incipient interaction between niobium and nickel oxides at low Nb/Ni atomic ratios is directly related to catalytic activity, and that a larger size well-defined NiNb(2)O(6) mixed oxide phase is not active for this reaction. Moreover, the promotion by niobium doping appears to be limited to a moderate niobium loading. It was found that in situ and operando Raman are valuable techniques that allowed the identification of active Mo-S and Ni-Nb species under reaction conditions, and that are not stable under air atmospheres.

HDS of 4,6-DMDBT over NiMoP/SBA-15 and NiMoP/(x)TiSBA-15 catalysts prepared using an heteropolyacid (H 3 PMo 12 O 40 ) and nickel citrate (C 12 H 10 Ni 3 O 14 ) as Mo and Ni precursors was studied. To analyze the effect of calcination temperature on HDS activity, catalysts noncalcined and calcined at 773 K were prepared. The performance of the different catalysts during the hydrodesulfurization of 4,6-dimethyldibenzothiophene was compared with that of a reference catalyst prepared by impregnation with a solution containing ammonium heptamolybdate and nickel nitrate. Kinetic parameters for the HDS of 4,6-DMDBT were estimated using a simplified kinetic model. The catalysts were characterized by N 2 physisorption, X-ray diffraction, Raman, and IR of adsorbed CO at ∼100 K. The results show that for catalysts supported on pure SBA-15 the noncalcined catalyst prepared with H 3 PMo 12 O 40 (NiMoP(H-nc)/SBA-15) presents the highest number of active sites, the higher apparent reaction rate constant for the hydrogenation route, and therefore the best 4,6-DMDBT HDS activity. In contrast, for Ti-modified catalysts, NiMoP/(x)Ti-SBA-15, the highest HDS activity was found when 15% of TiO 2 was incorporated to SBA-15 and the catalyst was calcined at 773 K. This catalyst presented the highest TOF.

Formation and dissociation conditions for methane hydrates were investigated in the presence of aqueous solutions of a no-ionic triblock copolymer synperonic PE/F127 (PE/F127) at 377, 710, 1530 ppm with the aim of evaluating the promotion activity. A cationic cetyltrimethylammonium bromide (CTAB) and an anionic sodium dodecyl sulfate (SDS) surfactant were also tested and conducted at 356, 705, 1500 ppm and 376, 701, 1510 ppm respectively. Experiments with the three surfactants were carried out in an isochoric autoclave under the same conditions: near the ice normal melting point (273.15 K), as the cooling temperature of the autoclave, and five initial pressures stated from 3.5 to 12.0 MPa. Performance of these surfactants was assessed by reporting hydrate−liquid water−vapor (H−L−V) phase equilibria, enthalpies of dissociation estimated using the Clausius− Clapeyron equation, induction times, crystallization temperatures, growth rates and theoretical methane consumptions. In brief, the obtained induction time for PE/F127 was higher than CTAB but lower than SDS, the growth rate between PE/F127 and SDS were similar at lower concentrations, and the maximum gas consumption for PE/F127 was reached at 1530 ppm but this methane uptake was far from those results using SDS.