Hydrogen Production via Glycerol Steam Reforming over Ni/Al₂O₃: Influence of Nickel Precursors

Abstract

This paper describes an investigation regarding the influence of Ni precursors on catalytic performances of Ni/ Al 2 O 3 catalysts in glycerol steam reforming. A series of Ni/ Al 2 O 3 is synthesized using four different precursors, nickel nitrate, nickel chloride, nickel acetate, and nickel acetylacetonate. Characterization results based on N 2 adsorption− desorption, X-ray diffraction, H 2 temperature-programmed reduction, H 2 chemisorption, transmission electron microscopy, and thermogravimetric analysis show that reduction degrees of nickel, nickel dispersion, and particle sizes of Ni/ Al 2 O 3 catalysts are closely dependent on the anion size and nature of the nickel precursors. Ni/Al 2 O 3 prepared by nickel acetate possesses the moderate Ni reduction degree, high Ni dispersion, and small nickel particle size, which possesses the highest H 2 yield. Reaction parameters are also examined, and 550 °C and a steam-to-carbon ratio of 3 are optimized. Moreover, coke deposition, mainly graphite species, leads to the deactivation of Ni/Al 2 O 3 catalysts in glycerol steam reforming. Nickel chloridederived Ni/Al 2 O 3 catalysts suffer from severe coke deposition and low reaction activity due to large Ni particle size, low Ni dispersion, and residual chloride.

Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

“…The growth rate was found to show a rough tendency to increase with decreasing crystallite size. For catalysts in which Ni species are supported on oxides, the decrease in the crystallite size of Ni species can contribute to improvement of its dispersion degree on the support, resulting in enhancement of the catalytic activity due to an increase in interaction between the Ni species and the support (Wu et al 2013). Our catalysts may also activate according to a similar mechanism.…”

Effect of Size and Distribution of Ni Nanoparticles on γ-Al2O3 in Oleic Acid Hydrodeoxygenation to Produce n-Alkanes

“…The main peaks corresponding to the probable introduction of NiO into the material at 37 • and 43 • [23] were not recorded in the DRX pattern due to the overlap with the γ-Al 2 O 3 intense peaks. Nevertheless, the presence of Ni was detected on the Ni/γ-Al 2 O 3 catalysts since the weak peak at~77 • corresponds to the crystallites of Ni [24], which is almost undetectable in the NAL-3 sample. Figure 2a shows XPS spectra of Ni/γ-Al 2 O 3 catalysts with different weight percentages of Ni (3, 5, and 7).…”

Direct Synthesis of Methane from Glycerol by Using Silica-modified Nickel Catalyst

“…On the other hand, the exothermic peak with the weight loss was derived from the combustion of coke. Weight loss below 773 K is ascribed to the combustion of filamentous or encapsulated carbon species 40) . The combustion of nickel carbide occurs at low temperatures in the range of 523-723 K, while the prominent peak derived from carbonaceous species appears at high temperatures in the range of 673-873 K 48), 49) .…”