Highly Efficient Ni-Phyllosilicate Catalyst with Surface and Interface Confinement for CO₂ and CO Methanation

Abstract

For the conventional Ni/SiO 2 catalyst, it is a challenge to address the sintering problem of Ni particles, especially at high Ni loading. A series of Ni-phyllosilicate catalysts were prepared through the hydrothermal reaction of mesoporous SiO 2 nanorods (SRs) and nickel nitrate, followed by an impregnation modification of CeO 2 . Hydrothermal temperature played an important role in the formation of nickel phyllosilicate. A small amount of Ni-phyllosilicate with a Ni content of 18.56 or 23.88 wt % was formed at a low hydrothermal temperature of 120 or 160 °C, and a large amount of nanosheet-like Ni-phyllosilicate with the Ni content as high as 31.65 wt % was obtained at a high hydrothermal temperature of 200 °C. The prepared Niphyllosilicate catalysts were beneficial to obtain Ni particles with small sizes (3.3−6.3 nm), even though they were reduced at 750 °C and possessed high Ni loadings (18.56−31.65 wt %) owing to the surface and interface confinement of nickel phyllosilicate. After the modification of CeO 2 using an impregnation method, the CeO 2 promoter could further reduce the Ni particle size and increase hydrogen and carbon dioxide uptakes. The CeO 2 -modified Niphyllosilicate catalyst (NPS-180-5C) was the best catalyst in this work, which could reach the thermodynamic equilibrium of CO methanation above 350 °C and exhibited high catalytic activity for CO 2 methanation. In addition, for the 55 °C-100 h-lifetime test for CO 2 methanation and 600 °C-6 h-100% steam treatment tests, NPS-180-5C also showed an excellent antisintering property and higher hydrothermal stability than the impregnated one (N/SR-Im) owing to its special structure and confinement effect as well as promotion of CeO 2 species. In all, the CeO 2 -modified SR-derived Ni-phyllosilicate catalyst could not only effectively suppress the problem of easy sintering of metallic Ni particles on the conventional Ni/SiO 2 catalysts but also exhibit high catalytic activity and hydrothermal stability, which was a promising catalyst for both CO 2 and CO methanation reactions.

Embedded Structure of Ni@PSi Catalysts for Steam Reforming of Methane

“…Peaks corresponding to SiO 2 (PDF#27-0605) were detected in all samples because of the incomplete reduction from SiO 2 to PSi. [23] The Ni phyllosilicate precursor exhibited the strong diffraction peaks at 19.4°, 56.7°, 33.7°, 39.7°, 53.2°and 60.9°, which were originated from 2 : 1 Ni-PSi structure (PDF#43-0664), [25] though some of them overlapped with other diffractions. The Ni@PSi-400, 500, 600, 700 samples kept these diffractions well, but they became very vague over the Ni@PSi-850 catalyst.…”

Photo‐Assisted CO/CO2 Methanation over Ni/TiO2 Catalyst: Experiment and Density Functional Theory Calculation

“…The peaks with binding energies near 852 eV correspond to Ni 0 peaks. The presence of Ni 2+ and Ni 3+ species in the sample after hydrogen reduction can be are observed because it is difficult to avoid the partial oxidation of the surface metallic Ni in the ex situ operation of XPS analysis [35] . We note that all of the deconvolved peaks observed for both methanation reactions shifted to higher binding energy values after the reaction under no light irradiation than those observed prior to the reaction.…”

Silica-Decorated NiAl-Layered Double Oxide for Enhanced CO/CO2 Methanation Performance

“…The center position of the peak at 852.8 eV corresponded to Ni 0 , which is the active metal Ni monomer after H 2 reduction, the amount of which has an important influence on the catalytic activity. The center position at 855.4 and 873.7 eV corresponded to Ni 2+ , which may be due to the fact that the H 2 reduction at 500 °C may not be sufficient to oxidize the difficult-to-reduce Ni-Al oxides to Ni 0 and that it is difficult to avoid some Ni being oxidized during the non-in situ XPS characterization [ 36 ]. The center position at 857 and 877.7 eV corresponded to Ni 3+ , possibly originating from Ni 2 O 3 [ 37 ].…”