OXIDATIVE-REFORMING OF METHANE AND PARTIAL OXIDATION OF METHANE REACTIONS OVER NiO/PrO2/ZrO2 CATALYSTS: EFFECT OF NICKEL CONTENT

Abstract

-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.

Dry reforming of methane over Zr- and Y-modified Ni/Mg/Al double-layered hydroxides

“…The size of ZrO2 primary crystallites (calculated from the Scherrer equation using the 2θ diffraction peak at 31°), was 11 nm for the Zr-containing materials. This is in agreement with the study of Asencios et al [19], where ZrO2 crystallites with non-variable size were detected by XRD. Moreover, the calculated mean Ni crystallite size (at 2θ ca.…”

“…Y 3+ [9,17,18]. This results in the formation of defects in the crystal structure of zirconia, together with oxygen vacancies in its oxygen sub-lattice, which are known as beneficial in the minimization of carbon deposits [9,[19][20][21]. The ZrO2-Y2O3 solid solution was studied in the past in different reforming processes [20][21][22][23].…”

Catalytic partial oxidation of methane to syngas: review of perovskite catalysts and membrane reactors

“…The result suggested that PrO2 contributed to the formation of Ni 0 active phases due to high metal dispersion and metal-support interaction in contrast [74].…”

Concurrent and modulated separation of CO2 and O2 by a fluorite/perovskite‐based membrane

“…In this sense, it has been reported that by changing the molar relation of reactants in the ORM, the H 2 /CO ratio in the obtained syngas could be controlled for further synthetic (5 purposes. 46 Indeed, the possibility of increasing the H 2 /CO ratio of the syngas has been reported by changing the O 2 /CH 4 ratio in the process. This approach is based on the contribution of the two reactions involved in the ORM process; the partial oxidation of methane and the dry reforming of methane (Equations 5 and 6).…”