Renewable hydrogen production via glycerol steam reforming over Ni/CeO2 catalysts obtained by solution combustion method: The effect of Ni loading

• Published in: Fuel processing technology Vol. 236; p. 107429
• Main Authors: Omarov, Shamil O., Martinson, Kirill D., Matveyeva, Anna N., Chebanenko, Maria I., Nevedomskiy, Vladimir N., Popkov, Vadim I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2022
• Subjects: Ceria; Glycerol; Nickel; Solution combustion synthesis; Steam reforming; Glycerol; Nickel; Steam reforming; Solution combustion synthesis; Ceria
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2022.107429

A series of nanocrystalline Ni/CeO2 catalysts with various Ni content was prepared by urea-nitrate combustion synthesis and evaluated in glycerol steam reforming for renewable H2 production. The as-prepared, reduced and spent catalysts were characterized by various analytical techniques such as XRD, N2-physisorption, SEM–EDX, TEM–HAADF and SAED, H2-TPR, XPS, Raman, and DTA–TGA. NiO is predominantly in the X-ray amorphous state (particle size 2–4 nm regardless of the Ni amount), which is retained for Ni0 particles after reduction by H2. Significant fraction of NiO(Ni0) is localized between CeO2 aggregates. An increase in the Ni content leads to inhibition of the agglomeration of CeO2 crystallites and increase in CeO2 defectiveness up to 6.8 wt% Ni; formation of CeO2(Ni2+) solid solution at 8.7 wt% Ni, which decomposes upon reduction. The sample containing 6.8 wt% Ni exhibits the best combination of Ni content and dispersion, CeO2 defectiveness, glycerol conversion, H2 yield, selectivity to H2 and CO2 and has low selectivity to hydrocarbons. TEM and DTA–TGA revealed the formation of amorphous, graphite-like, and fibrous coke depending on the Ni amount. This formation leads to accelerated deactivation due to partial agglomeration of Ni0 particles and encapsulation of amorphous nickel. [Display omitted] •xNi/CeO2 (x = 0–8.5 wt%) catalysts were synthesized via solution combustion method.•Thermostable amorphous (2–4 nm) NiO and Ni0 nanoparticles.•Maximum CeO2 defectiveness at 6.8 wt% Ni due to electronic effect.•6.8 wt% is the minimal Ni amount for the high hydrogen yield in GSR.•Amorphous, graphitic, and fibrous coke, encapsulation of amorphous Ni.