Structure-activity relationship in water-gas shift reaction over gold catalysts supported on Y-doped ceria

NiFe2O4@B,N,F-tridoped CeO2 (NFTDNC): a mesoporous nanocatalyst in the synthesis of pyrazolopyranopyrimidine and 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives and as an adsorbent

Mesoporous materials, due to their unique textural and structural features and successful applications in different scientific areas, engrossed our curiosity to form a mesoporous nanostructure. A facile method for the formation of nickel ferrite immobilized over B,N,F tridoped mesoporous cerium oxide (CeO₂) nanostructures (NFTDNC) was designed and communicated in this report. It was characterized by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction study (PXRD), scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy (HR-TEM), field emission gun-scanning electron microscopy (FE-SEM), vibrating sample magnetometry (VSM), photoluminescence (PL), Brunauer-Emmett-Teller (BET), energy dispersive X-ray analysis (EDX) and elemental mapping, UV-visible spectroscopy (UV-VIS) and Fourier transform infrared spectroscopy (FT-IR). The applications of the mesoporous nanomaterial (NFTDNC) as an adaptable heterogeneous nanocatalyst and as a phenomenal adsorbent for methyl orange (MO) dye were established. It catalyzed the formation of pyrazolopyranopyrimidine and 1H-pyrazolo[1,2-b]phthalazine-5,10-diones derivatives for the five runs. The recycled catalyst exhibited agglomeration in structural features confirmed by PXRD and HR-TEM studies. NFTDNC as an adsorbent fitted the Freundlich isotherm for the adsorption of MO dye. Moreover, it followed the linear pseudo-second-order kinetics rate equation (R² ≥ 0.98914). MO was adsorbed completely in 60 min with the NFTDNC mesoporous nanostructure.

Tuning the Integration Rate of Ce(Ln)O2 Nanoclusters into Nanoparticulated ZrO2 Supports: When the Cation Size Matters

Three nanostructured catalysts with low total rare earth elements (REEs) content (i.e., 15 mol.%) were prepared by depositing CeO₂ or Ln³⁺-doped CeO₂ (Ln³⁺ = Y³⁺ or La³⁺; Ln/Ce = 0.15) on the surface of ZrO₂ nanoparticles, as nanometre-thick, fluorite-type clusters. These samples were subjected to successive reduction treatments at increasing temperatures, from 500 to 900 °C. A characterisation study by XPS was performed to clarify the diffusion process of cerium into the bulk of ZrO₂ crystallites upon reduction to yield Ce_xZr_1-xO_2-δ surface phases, and the influence of the incorporation of non-reducible trivalent REE cations, with sizes smaller (Y³⁺) and larger (La³⁺) than Ce⁴⁺ and Ce³⁺. For all nanocatalysts, a reduction treatment at a minimum temperature of 900 °C was required to accomplish a significant cerium diffusion. Notwithstanding, the size of the dopant noticeably affected the extent of this diffusion process. As compared to the undoped ZrO₂-CeO₂ sample, Y³⁺ incorporation slightly hindered the cerium diffusion, while the opposite effect was found for the La³⁺-doped nanocatalyst. Furthermore, such differences in cerium diffusion led to changes in the surface and nanostructural features of the oxides, which were tentatively correlated with the redox response of the thermally aged samples.

Au–CeO2-based nanocatalysts supported on SBA-15 for preferential oxidation of carbon monoxide (PrOx-CO)

Highly dispersed Au–CeO₂ nanoparticles were deposited within the pores of a mesoporous silica for the catalysis of the PrOx-CO reaction.