CO and CO2 methanation over Ni catalysts supported on CeO2, Al2O3 and Y2O3 oxides

Abstract

In this paper, the methanation of carbon oxides (CO and CO 2 ) was studied as an interesting way to provide a renewable energy source of synthetic natural gas (SNG) simultaneously reducing the emission of greenhouse gases. 15 wt.% Ni-based catalysts supported on CeO 2 , Al 2 O 3 and Y 2 O 3 oxides were synthesized by solution combustion synthesis. Then, a second series on Ni/Y 2 O 3 catalysts was prepared with different Ni loading (7-35 wt.%). The physicochemical properties of the catalysts were characterized by N 2 -physisorption, XRD, H 2 -TPR, CO-chemisorption, TEM, UV-Vis DRS, XPS, and CO 2 -TPD. The effect of reaction temperature (250-500°C) was investigated under atmospheric pressure, space velocity (GHSV) of 10,000 h −1 , and stoichiometric reactants ratio of (H 2 -CO 2 )/(CO+CO 2 ) = 3. A 200 h stability test was also carried out at 350°C over the 25 wt.% Ni/Y 2 O 3 catalyst. It can be concluded that the nature of Ni-support interactions played a crucial role in enhancing CO and CO 2 hydrogenation at relatively low reaction temperature. Ni/CeO 2 catalyst deactivated rapidly due to coke deposition, while the formation of NiAl 2 O 4 spinel was the main reason of the lower activity of the Al 2 O 3 -supported system. Activity data for Ni/Y 2 O 3 catalysts were closely related to the degree of Ni dispersion as well as to the medium-strength basicity. Good anti-coking and anti-sintering ability were observed after 200 h of lifetime test over the 25Ni/Y 2 O 3 catalyst.

Understanding structure-activity relationships in highly active La promoted Ni catalysts for CO2 methanation

“…Strikingly, the trend in the activity is Y2O3 > CeO2 > Al2O3 > La2O3 for Ni supported on pure oxides [17] yet when these oxides are used to modify Ni/Al2O3, the trend changes accordingly to La2O3 > CeO2 > Y2O3 [27]. In contrast, Italiano et al reported that for 15 wt.% Ni supported on pure oxides, the activity performance decreases in the order Y2O3 > Al2O3 > CeO2 [36]; Ni/CeO2 deactivated by coke deposition. The dispersion of Ni and rare-earth elements, the interaction between them and with the oxide matrix may be responsible for these apparently contradictory behaviors, though this has not specified in the literature.…”

Barium promoted Ni/Sm2O3 catalysts for enhanced CO2 methanation

“…Hysteresis loop presence at high relative pressure (p/p o > 0.7) implied a broad pore size distribution, comprising both meso-and macropores in the catalysts structure. 21 Pore size distribution analysis (Fig. 2b) showed the formation of mesopores on 5Ni-5Ba/Sm 2 O 3 catalyst.…”

Effect of the Addition of Alkaline Earth and Lanthanide Metals for the Modification of the Alumina Support in Ni and Ru Catalysts in CO2 Methanation

“…Second, the peak appearing in the moderate region, at 473 K, is due to bicarbonate formation on the catalyst surface. Finally, when the interaction between CO 2 and catalyst is stronger (750 K), the formation of monodentate bicarbonate species takes place [60]. In the 1Ru-13Ni/14La-Al 2 O 3 , 13Ni/14Ce-Al 2 O 3 , and 13Ni/10Ca-Al 2 O 3 catalysts, the formation of bicarbonate species is facilitated at lower temperatures, with the corresponding peak appearing at a temperature of approximately 423 K. The incorporation of Ba and Ca to the 13Ni/Al 2 O 3 catalyst produces an increase in strong basic centers (although without reaching the one that produces 13Ni/10Mg-Al 2 O 3 ), shifting the peak corresponding to the formation of monodentate bicarbonate species to 808 and 846 K, respectively.…”