Cerium-Based Bimetallic Oxides as Catalysts for the Methanation of CO₂: Influence of the Preparation Method

Abstract

Cerium-based bimetallic oxides of the type 3NiO·CeO2, Co3O4·CeO2, and 1.5Fe2O3·CeO2 were prepared by two sol–gel methods (epoxide addition and Pechini methods) and by the electrospinning technique, aiming at the synthesis of compounds with different morphologies (nanoparticles or nanofibers) and the evaluation as catalysts for the methanation of CO2. The results obtained show a catalytic performance that depends on the type of d block element, method, and catalyst morphology. Regardless of such parameters, the best results were those obtained over the nickel-based catalysts prepared by the electrospinning technique that are remarkably more active than a commercial rhodium catalyst used as a reference and tested in the same conditions. Moreover, the cobalt-based catalysts obtained either as nanoparticles (Pechini method) or fibers (electrospinning technique) present also a good activity, comparable to that measured over the reference catalyst. All catalysts were very stable to deactivation during at least 60–70 h of reaction, which is clearly an advantage that could make them an alternative to be considered for future developments in this area of knowledge.

Facile In Situ Synthesis of Co(OH)2–Ni3S2 Nanowires on Ni Foam for Use in High-Energy-Density Supercapacitors

“…According to a review of recent advances in carbon-based materials for use in supercapacitor electrodes, the specific energy is generally <10 Wh kg −1 [3,6,7]. Recently, mono-and bimetallic oxides, layered double hydroxides, and transition metal sulfides were proposed to overcome the lower energy densities in supercapacitors [8][9][10][11]. The transition metal sulfides (nickel or cobalt sulfide) exhibited considerable potential; in particular, nickel Nanomaterials 2022, 12, 34 2 of 15 sulfides exhibit excellent electrochemical energy storage and fascinating properties, such as excellent redox reversibility, conductivities, and capacitances [12][13][14][15].…”

Nitrogen-Doped Ni/TiO2 Catalyst with Enhanced Activity and Improved Selectivity for CO2 Methanation

“…On the basis of the Scherrer equation, the average crystallite size of Ni nanoparticles on the Ni/TiO 2 , Ni/N 2.5 -TiO 2 , Ni/N 10 -TiO 2 , and Ni/N 12.5 -TiO 2 catalysts was estimated as 16.2, 15.7, 12.9, and 14.8 nm, respectively. The smaller Ni particle size on the N-doped Ni/TiO 2 catalysts may partially rationalize the enhanced activity observed . Moreover, it is noted that the introduction of N dopants would significantly modulate the phase composition of TiO 2 .…”

“…On the basis of the literature, , the peaks in the range of 395–399 eV were assigned to substituted N species, wherein the Ti–N linkage was formed by replacing O anions with N anions. The peaks around 400.1 eV were ascribed to interstitial N, which corresponded to the Ti–O–N bond. ,, In addition, the peaks above 400.5 eV were attributed to oxidized N species originating from Ti–NO or Ti–NO 2 bonds. , According to the integral area of three deconvoluted peaks, the distribution of various N species was derived. By comparison of Figure b to Figure , it is noted that the evolution of substituted N correlated well with the change of the methanation performance on the N-doped Ni/TiO 2 catalysts.…”

“…The smaller Ni particle size on the N-doped Ni/TiO 2 catalysts may partially rationalize the enhanced activity observed. 29 Moreover, it is noted that the introduction of N dopants would significantly modulate the phase composition of TiO 2 . The proportion of the rutile phase followed the sequence of Ni/N 10 -TiO 2 (64.0%) > Ni/N 12.5 -TiO 2 (63.1%) > Ni/N 2.5 -TiO 2 (53.0%) > Ni/TiO 2 (40.0%).…”

“…The peaks around 400.1 eV were ascribed to interstitial N, which corresponded to the Ti−O−N bond. 26,28,29 In addition, the peaks above 400.5 eV were attributed to oxidized N species originating from Ti−NO or Ti−NO 2 bonds. 39,41 According to the integral area of three deconvoluted peaks, the distribution of various N species was derived.…”