Catalisadores Ni/Al2O3 promovidos com molibdênio para a reação de reforma a vapor de metano Mo-Ni/AL2O3 catalysts for the methane steam reforming reaction

<abstract language="eng">Mo-promoted Ni/Al2O3 catalysts for the methane steam reforming reaction were studied in this work. The Ni/Al2O3 catalysts were prepared by precipitation and molibdenum was added by impregnation up to 2%wt. The solids were tested using a micro-reactor under two H2Ov/C conditions and were characterized by ICP-OES, XRD, N2 adsoption, H2 chemisorption and TPR. NiO and NiAl2O4 phases were observed and the metallic area decreased with the increase of the Mo content. From the catalytic tests high stability was verified for H2Ov/C=4.0. On the other hand, only the catalyst containing 0,05% Mo stayed stable during 30 hours of the test at H2Ov/C=2.0

Estudo da reação de oxidação preferencial do co sobre o sistema CuO/CeO2-TiO2

Cu catalysts supported on CeO2, TiO2 and CeO2/TiO2 were prepared by precipitation method and used for preferential oxidation of carbon monoxide contained in a hydrogen flow generated by methane steam reforming. The samples were characterized by XRD, BET and TPR techniques. The catalytic properties were studied in the 50-330ºC range by using a quartz micro-reactor vertically positioned on an electrical furnace. The results showed that the small copper particles generated with the lower metal content are the most easily reducible and give the best catalytic performance. In respect of support effect, the strong metal-support interaction and the redox characteristics of the CuOx-CeO2 series resulted in the best catalytic results, especially with the sample with 1% copper content

Síntese e caracterização de perovskitas LaNi(1-x)Co xO3 como precursores de catalisadores para a conversão do metano a gás de síntese pela reforma com CO2

LaNiO3 perovskite was modified by partial substitution of nickel by cobalt in order to increase the stability and resistance to carbon deposition during the methane CO2 reforming. The results showed that a suitable combination of precipitation and calcination steps resulted in oxides with the desired structure and with important properties for application in heterogeneous catalysis. The partial substitution of Ni by Co resulted in lower rates of conversion of both the reactants, but the catalyst stability was highly increased. The LaNi0.3Co0.7O3 catalyst, calcined at 800 ºC, was the most active under the reaction conditions

Support influence on the basicity promotion of lithium-based mixed oxides for transesterification reaction

Solid catalysts comprising Li-based oxides were prepared by LiNO3 impregnation onto supports with different acid/base properties (SiO2, MgO, Al2O3 and Mg(Al)O mixed oxide obtained from hydrotalcite). The materials were characterized by means of XRD, N2 physisorption, ICP?OES, FEG-SEM and TPD of CO2. The oxide reactivities were evaluated using the model transesterification reaction between methyl acetate and ethanol under mild reaction conditions (313 K, ethanol/methyl acetate molar ratio = 6/1 and 0.2 wt.% of catalyst). Lithium impregnation onto silica and c-alumina yielded inactive catalysts for transesterification. On the other hand, the lithium addition onto MgO produced an active catalyst and remarkably high conversions were obtained for Li/Mg(Al)O. The different supports used considerably affected the base site densities and base strengths of the Li-based catalysts. The base properties thus influenced the catalytic performance of the materials. Stability tests revealed the lithium leaching occurrence which resulted in some homogeneous contribution.Fil: Castro, Cinthia S.. Universidade Federal do Sao Carlos; BrasilFil: Ferretti, Cristián Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Catalysis Science and Engineering Research Group (GICIC); ArgentinaFil: Di Cosimo, Juana Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Catalysis Science and Engineering Research Group (GICIC); ArgentinaFil: Mansur Assaf, José. Universidade Federal do Sao Carlos; Brasi

Effect of gadolinium on the catalytic properties of iron oxides for WGSR

Due to the need for energy supply through cleaner and more efficient technologies, the interest for the water gas shift reaction (WGSR) has increased especially due to its role in purifying hydrogen-rich streams. In order to find alternative catalysts for this reaction, the effect of gadolinium and its amount on the properties of iron oxide-based catalysts was studied in this work. Samples with different gadolinium to iron molar ratio (0.05; 0.1 and 0.15) were prepared by sol–gel method and characterized by chemical analysis, thermogravimetry, differential scanning calorimetry, infrared spectroscopy, X-ray diffraction, Mossbauer spectroscopy, specific surface area measurements and thermoprogrammed reduction. The catalysts were evaluated in WGSR at 1 atm in the range of 250–400 °C. Hematite and gadolinium ferrite were detected for all fresh catalysts based on iron and gadolinium while magnetite and iron carbides and gadolinium oxide were found for the spent ones. The specific surface area increased due to gadolinium, related to its role as spacer. Gadolinium made the reduction of Fe³⁺ and Fe²⁺ species more difficult for all catalysts and then inhibited the production of iron carbides during reaction, increasing the activity. The catalyst with Gd/Fe = 0.10 showed the highest activity that was assigned to its highest specific surface area, which exposed more active sites. No methane or ethane was found indicating that the iron carbides were inactive to Fischer–Tropsch synthesis under reaction conditions.Centro de Investigación y Desarrollo en Ciencias Aplicada