Ce- and Y-Modified Double-Layered Hydroxides as Catalysts for Dry Reforming of Methane: On the Effect of Yttrium Promotion

Abstract

Ce- and Y-promoted double-layered hydroxides were synthesized and tested in dry reforming of methane (CH4/CO2 = 1/1). The characterization of the catalysts was performed using X-ray fluorescence (XRF), X-ray diffraction (XRD), N2 sorption, temperature-programmed reduction in H2 (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), H2 chemisorption, thermogravimetric analysis coupled by mass spectrometry (TGA/MS), Raman, and high-resolution transmission electron microscopy (HRTEM). The promotion with cerium influences textural properties, improves the Ni dispersion, decreases the number of total basic sites, and increases the reduction temperature of nickel species. After promotion with yttrium, the increase in basicity is not directly correlated with the increasing Y loading on the contrary of Ni dispersion. Dry reforming of methane (DRM) was performed as a function of temperature and in isothermal conditions at 700 °C for 5 h. For catalytic tests, a slight increase of the activity is observed for both Y and Ce doped catalysts. This improvement can of course be explained by Ni dispersion, which was found higher for both Y and Ce promoted catalysts. During DRM, the H2/CO ratio was found below unity, which can be explained by side reactions occurrence. These side reactions are linked with the increase of CO2 conversion and led to carbon deposition. By HRTEM, only multi-walled and helical-shaped carbon nanotubes were identified on Y and Ce promoted catalysts. Finally, from Raman spectroscopy, it was found that on Y and Ce promoted catalysts, the formed C is less graphitic as compared to only Ce-based catalyst.

Highly Carbon-Resistant Y Doped NiO–ZrOm Catalysts for Dry Reforming of Methane

“…While for the NiO-ZrOm-YOn catalyst, it decreases from 16 nm to 10 nm after reaction for 8 h, which indicates the re-dispersion of Ni 0 . Similar phenomenon had been reported by other researches [37,38,42]. Nakayam et al [43] found the redispersion of Ni under an alternating condition between H2 reduction and oxidation atmosphere.…”

Improved Water–Gas Shift Performance of Au/NiAl LDHs Nanostructured Catalysts via CeO2 Addition

“…These components correspond to various types of Ni 2+ species with different reducibility due to a complex interaction between the components of LDHs. Despite the appearance of weak low-temperature peaks, the shift to a higher temperature of reduction implies that ceria hampers reducibility, as reported recently by Swirk et al [ 74 ]. This effect of ceria on reduction behavior could explain lower WGS activity of ceria-modified LDHs ( Figure 3 a).…”

Novel Nickel- and Magnesium-Modified Cenospheres as Catalysts for Dry Reforming of Methane at Moderate Temperatures

“…H 2 consumption indicates that a small amount of NiO was present after DRM. The presence of this reduction peak in the spent catalysts may point out that Ni particles were repeatedly oxidized and reduced during DRM process [35,41] (Table 1).…”