Nickel-based catalyst derived from NiO–Ce0.75Zr0.25O2 nanocrystalline composite: Effect of the synthetic route on the partial oxidation of methane (original) (raw)
Related papers
Catalysts, 2018
Nickel catalysts supported on homemade CeO 2 oxide were prepared by two procedures intending to achieve different degree of metal-support interaction. One method consisted of a co-precipitation that was assisted by microwave; the other method was based on a modified wetness impregnation in the presence of the organic complexing ligand, nitrilotriacetic acid (NTA). The support and catalysts were characterized by temperature programmed reduction (TPR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. Significant differences in the structure, in redox properties and in the elemental surface composition emerged. The catalytic behavior in the partial oxidation of methane was tested at atmospheric pressure, in a range of temperature between 400-800 • C, using diluted feed gas mixture with CH 4 /O 2 = 2 and GHSV = 60,000 mL g −1 h −1. Moreover, the effect of the catalyst reduction pretreatment was investigated. The better catalytic performance of the microwave-assisted sample as compared to the NTA prepared sample was attributed to the stronger interaction of nickel with CeO 2. Indeed, according to the structural and reducibility results, an adequate electronic contact between the metal and the support favors the formation of oxygen vacancies of ceria and inhibits the sintering of the catalyst active species, with an improvement of the catalytic performance.
Methane partial oxidation using Ni/Ce0.9Zr0.1O2 catalysts
International Journal of Hydrogen Energy, 2008
The development of active and selective catalysts for methane partial oxidation is one of today's challenges, because these catalysts could be used either for hydrogen production purposes or as anode materials in single-chamber solid oxide fuel cells (SOFCs). In this work, the synthesis of ceria-zirconia solid solutions of nominal composition Ce 0.9 Zr 0.1 O 2 through the gel-combustion route is presented. The solids obtained were impregnated with nickel solutions to achieve contents of 9% and 50% (m/m), characterized texturally and structurally, and their catalytic behavior in the methane partial oxidation reaction was assessed. The synthesis method was effective, leading to solids with good morphological properties. Likewise, the Ni/Ce 0.9 Zr 0.1 O 2 catalysts proved to be active and showed a stable behavior during the working period, with methane conversion levels of 90% at temperatures above 550 1C, being hydrogen and carbon monoxide the main products.
Catalysis Today, 2008
The preparation of three different types of mixed nickel oxides is described. These systems include: (i) the perovskite LaNiO3 oxide, (ii) a mixed-oxide derived from a hydrotalcite Ni–Al (64:38) precursor, and (iii) the spinel-type NiAl2O4 oxide. These systems were prepared with the aim of studying the activation procedure that develops small nickel nanoparticles deposited on a La2O3 or Al2O3 substrate active in H2 production through catalytic decomposition of CH4. Different preparation procedures have been applied to each precursors (i)–(iii). Perovskite-type oxide LaNiO3 was prepared by the sol–gel methodology (citrates method). Mixed oxide derived from hydrotalcite was obtained by co-precipitation using urea as a basic agent. NiAl2O4 spinel synthesis was performed by the ceramic method. The three oxide-type materials were characterized by XRD, BET specific area, TPR and XPS. Characterization results showed that the preparation methods used allow formation of highly crystalline and homogeneous oxide precursors. After activation, the oxide precursors showed a high activity in the decomposition reaction of CH4. The catalysts derived from hydrotalcite mixed oxide showed the highest activity with CH4 conversions reaching 50% at 500 °C.
Preparation and characterization of nickel based multicomponent catalysts
Journal of Physics: Conference Series, 2009
The preparation of three different types of mixed nickel oxides is described. These systems include: (i) the perovskite LaNiO 3 oxide, (ii) a mixed-oxide derived from a hydrotalcite Ni-Al (64:38) precursor, and (iii) the spinel-type NiAl 2 O 4 oxide. These systems were prepared with the aim of studying the activation procedure that develops small nickel nanoparticles deposited on a La 2 O 3 or Al 2 O 3 substrate active in H 2 production through catalytic decomposition of CH 4 . Different preparation procedures have been applied to each precursors (i)-(iii). Perovskite-type oxide LaNiO 3 was prepared by the sol-gel methodology (citrates method). Mixed oxide derived from hydrotalcite was obtained by co-precipitation using urea as a basic agent. NiAl 2 O 4 spinel synthesis was performed by the ceramic method. The three oxide-type materials were characterized by XRD, BET specific area, TPR and XPS. Characterization results showed that the preparation methods used allow formation of highly crystalline and homogeneous oxide precursors. After activation, the oxide precursors showed a high activity in the decomposition reaction of CH 4 . The catalysts derived from hydrotalcite mixed oxide showed the highest activity with CH 4 conversions reaching 50% at 500 8C. #
Materials
In order to clarify the role of R2O3 in the metal-oxide catalysts derived from complex oxide precursors, a series of R1.5Ca0.5NiO4 (R = Nd, Sm, Eu) complex oxides was obtained. A significant systematic increase in the orthorhombic distortion of the R1.5Ca0.5NiO4 structure (K2NiF4 type, Cmce) from Nd to Eu correlates with a corresponding decrease in their ionic radii. A reduction of R1.5Ca0.5NiO4 in the Ar/H2 gas mixture at 800 °C causes a formation of dense agglomerates of CaO and R2O3 coated with spherical 25–30 nm particles of Ni metal. The size of metal particles and oxide agglomerates is similar in all Ni/(R2O3,CaO) composites in the study. Their morphology is rather similar to the products of redox exsolution obtained by the partial reduction of complex oxides. All obtained composites demonstrated a significant catalytic activity in the dry reforming (DRM) and partial oxidation (POM) of methane at 700–800 °C. A systematic decrease in the DRM catalytic activity of composites fro...
Study of nickel, lanthanum and niobium-based catalysts applied in the partial oxidation of methane
Catalysis Today, 2018
Catalysts based on nickel, niobium and lanthanum were obtained from precursors such as LaNiO3, LaNi0.5Nb0.5O3 and NiO/Nb2O5 and evaluated in the partial oxidation of methane (POM). X-ray diffraction (XRD) in situ studies using synchrotron light, under H2, indicate that after reduction the LaNiO3 perovskite precursor is transformed into Ni 0 /La2O3. On the other hand, LaNi0.5Nb0.5O3 is converted into Ni 0 /La2O3-LaNbO4 and NiO/Nb2O5 in Ni 0 /Nb2O5. Temperature programmed surface reaction (TPSR) indicates that only catalysts obtained from LaNiO3 and LaNi0.5Nb0.5O3 are active in the POM under the conditions investigated. XRD in situ studies using synchrotron light, under reaction atmosphere, show that nickel sites obtained from the precursor LaNi0.5Nb0.5O3 were less susceptible to oxidation. Long-term catalytic tests showed that the addition of niobium to LaNiO3 promotes the methane conversion per weight of nickel, a result which is associated with a larger nickel surface. This agrees with the mean crystallite size of nickel measured by XRD and with nickel particle size obtained from transmission electron microscopy (TEM). The regeneration of catalysts obtained from the precursors LaNiO3 and LaNi0.5Nb0.5O3 led to an increase in catalytic activity without a change in selectivity, and this can be attributed to a higher dispersion of the nickel particles after regeneration.
2010
Catalysts with different Ni contents supported on improved ZrO2-CeO2 mixed oxides and doped with manganese as a promoter of activity were evaluated on the catalytic methane decomposition (CMD) at 500 °C for hydrogen and carbon nanostructures production. The supports were synthesized by surfactant-assisted coprecipitation, and Ni and Mn deposition was performed by conventional impregnation. The surface areas for 15N1MZC and 45N1MZC solids prepared with surfactant were 13 and 28 m2/g respectively and it was observed that by incorporating 1% of Mn to the active phase the methane conversion increases. The temperature programmed reduction results indicated that the addition of Mn allows the formation of different NiOx species, increasing the reduction degree to Ni0. The transmission electron microscopy analysis show the formation of different species of carbon as nanotubes, whiskers and onions, as well as an important number of encapsulated Ni particles.
Ni:CeO2 nanocomposite catalysts prepared by polymeric precursor method
Applied Catalysis A: General, 2006
The biopolymer Chitosan was used as polymeric precursor for the synthesis of Ni:CeO 2 nanocomposite catalysts. Evidences for the formation of a hybrid polymer, of the Ce-citrate complex and the chitosan by polyesterification reaction, was provided by 13 C NMR and Raman spectroscopy. After the heat-treatment of the hybrid polymer at several temperatures, the materials were characterized by N 2 physisorption, H 2 and CO 2 chemisorption, XRD, EDX, TEM and Raman analyses. The results show that the presence of residual carbon has a positive influence on the samples properties. It was found that residual carbon contributes to a high surface area and to direct formation of Ni metal during the pyrolysis in N 2 atmosphere. In addition, due to the presence of residual carbon, the catalytic performance in CO 2 reforming of CH 4 indicated an enhanced stability and coking resistance of the catalysts. #
Catalytic partial oxidation of methane over Ni/CeO 2-ZrO 2-Al 2 O 3
2007
prepared and characterized by means of X-ray diffraction (XRD), BET areas, H, temperature-programmed reduction (H,-TPR), and X-ray photoelectron spectroscopy (XPS). Through the test of catalytic partial oxidation of methane (CPOM), Ni/CeO,-Zr0,-Al,O, displayed the highest activity, which resulted from its largest BET area and best NiO dispersion. Furthermore, Ni/CeO,-ZrO,-Al,O, maintained a long-time stability in CPOM, which was attributed to its best coking resistance among all the prepared catalysts.
Brazilian Journal of Chemical Engineering, 2016
In this work the behavior of NiO-PrO2-ZrO2 catalysts containing various nickel loadings was evaluated in the partial oxidation of methane and oxidative-reforming reactions of methane. The catalysts were characterized by X-Ray Diffraction Analysis (in situ-XRD), Temperature Programmed Reduction (H2-TPR), Scanning Electron Microscopy (SEM/EDX) and Adsorption-Desorption of nitrogen (BET area). The reactions were carried out at 750 °C and 1 atm for 5 hours. The catalysts were studied with different nickel content: 0, 5, 10 and 15% (related to total weight of catalyst, wt%). In both reactions, the catalyst containing the mixture of the three oxides (NiO/PrO2/ZrO2) with 15% nickel (15NiPrZr catalyst) showed the best activity for the conversion of the reactants into Syngas and showed high selectivity for H2 and CO. The results suggest that the promoter PrO2 and the Niº centers are in a good proportion in the catalyst with 15% Ni. Our results showed that low nickel concentrations in the catalyst led to high metallic dispersion; however, very low nickel concentrations did not favor the methane transformation into Syngas. The catalyst containing only NiO/ZrO2 in the mixture was not sufficient for the catalysis. The presence of the promoter PrO2 was very important for the catalysis of the POM.