CO Methanation over NiO-CeO2 Mixed-Oxide Catalysts Prepared by a Modified Co-Precipitation Method: Effect of the Preparation pH on the Catalytic Performance

Abstract

In this study, a series of NiO-CeO2 mixed-oxide catalysts have been prepared by a modified co-precipitation method similar to the one used for the synthesis of hydrotalcites. The syntheses were carried out at different pH values (8, 9 and 10), in order to determine the influence of this synthetic variable on the properties of the obtained materials. These materials were characterized by using different techniques, such as TGA, XRD, ICP, N2 adsorption-desorption isotherms, H2 temperature-programmed reduction (H2-TPR), and electron microscopy, including high-angle annular dark-field transmission electron microscopy (HAADF-TEM) and EDS. The characterization results revealed the influence of the preparation method, in general, and of the pH value, in particular, on the textural properties of the oxides, as well as on the dispersion of the Ni species. The catalyst prepared at a higher pH value (pH = 10) was the one that exhibited better behavior in the CO methanation reaction (almost 100% CO conversion at 235 °C), which is attributed to the achievement, under these synthetic conditions, of a combination of properties (metal dispersion, specific surface area, porosity) more suitable for the reaction.

Influence of X Cation Covalence in the Formation of Ni-O-X Mixed Oxides by Reactive Ion Beam Mixing of Ni/X Interfaces

“…In recent years, there has been an increasing demand of noble metals-free catalysts based in earth-abundant raw materials. In this way, Ni-based mixed oxides are being tested as promising candidates for substituting noble metal-based catalysts [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Ni-Co mixed oxides have been proposed for the catalytic oxidation of benzene [1] and their ability in O 2 activation during benzyl alcohol oxidation in air has also been addressed [2].…”

“…Likewise, Ni-Zr [11], Ni-Fe [12] and NiO/Mn-doped NiCo 2 O 4 [13] mixed oxides have been tested as catalysts for the oxygen evolution reaction [11,12], and Ni-Mn mixed oxides for ethanol oxidation [14]. Ni-In mixed oxides have been studied in the electroreduction of CO 2 [15], and Ni-Ce mixed oxides for the catalytic CO methanation reaction [16]. Likewise, Ni-Ge mixed oxides have been tested for the electrochemical nitrogen reduction reaction [17] and Ni-Sn mixed oxides as catalysts for carbonylation of amines by CO 2 .…”

Effect of Ce/Zr Composition on Structure and Properties of Ce1−xZrxO2 Oxides and Related Ni/Ce1−xZrxO2 Catalysts for CO2 Methanation

“…The impact of a support on the dispersion of nickel particles and catalytic performance of nickel catalysts is significant [6][7][8]. CeO 2 was shown to be one of the most effective support materials [6][7][8][9][10][11][12][13][14][15][16]. Ceria works as both a support for nickel particles and a reaction promoter.…”