Co-Al spinel-based nanoparticles synthesized by flame spray pyrolysis for glycerol conversion

Abstract

The catalytic properties of Co-Al spinel nanoparticles prepared by flame spray pyrolysis (FSP) were investigated in the glycerol conversion in gas phase in an atmosphere of hydrogen. Reduction under hydrogen atmosphere at 1123 K of the as-synthesized spinel nanoparticles induced the formation a new phase containing metallic cobalt species. Although, the reducibility of cobalt oxides is greatly decreased due to interaction with aluminium species, this strong interaction may prevent the aggregation of Co particles under the harsh reduction conditions. X-ray photoelectron spectroscopy (XPS) of the reduced spinel nanoparticles at 1123 K revealed that the Co/Al atomic ratio has decreased from 0.27 to 0.11, which represents a significant reduction in the exposed cobalt. This is in accordance with the reduction of CoAl 2 O 4 into metallic Co and partial agglomeration (sintering) of Co. X-ray diffraction (XRD) and high resolution electron microscopy (HRTEM) also reinforced the formation of metallic cobalt species after reduction of cobalt from the spinel nanoparticles at 1123 K. The main products obtained from the conversion of glycerol in the gas phase were hydroxyacetone, pyruvaldehyde, lactic acid and lactide. FSP successfully gave insights to ensure uniform dispersion of the active metal on a support material.

Insights into the Capacity and Rate Performance of Transition‐Metal Coordination Compounds for Reversible Lithium Storage

“…The HRTEM images show no distinct lattice fringes in states A and B (Figures S15b,c), indicating that they are amorphous. When further discharged to states C and D, the two main peaks shifted to 777.7 and 792.8 eV, and the satellite peaks vanished, confirming the reduction of Co 2+ to Co 0 , [28] which is also consistent with the lattice fringes of 0.177 nm and 0.11 nm in the HRTEM images and the diffraction rings in the SAED patterns (Figures S15d,e) [29] . In the charging process (states E–G), the main peaks shifted to 780.2 and 795.7 eV, and the satellite peaks at 785.5 and 804.2 eV of Co 2+ reappeared, and the lattice fringes in HRTEM images and the diffraction rings in the SAED patterns of Co 0 phase disappeared (Figures S15f–h), suggesting the oxidation from Co 0 to Co 2+ .…”

Recent Advances in the Catalytic Production of Platform Chemicals from Holocellulosic Biomass

“…They identified metallic Ni species as participants in the hydrogenolysis route of glycerol, whereas NiO sites promote its dehydration forming methane and hydroxyacetone. In a similar work, they also identified non‐noble metals like cobalt as key players for glycerol conversion into hydroxyacetone, pyruvaldehyde, lactic acid and lactide . An attractive monomer, 1,3‐propanediol, is increasingly being produced from glycerol since the late 1980s.…”

Insights on the One‐Pot Formation of 1,5‐Pentanediol from Furfural with Co−Al Spinel‐based Nanoparticles as an Alternative to Noble Metal Catalysts

“…[18] The FSP system used for particle preparation has been described previously. [18] The FSP system used for particle preparation has been described previously.…”