A highly efficient and stable Ni/SBA-15 catalyst for hydrogen production by ethanol steam reforming

The production of hydrogen by steam reforming of ethanol was carried out on SBA-15-supported nano NiO catalyst synthesized by the equivalent-volume impregnation method with two different Ni sources (nickel nitrate and nickel sulfamate). The catalyst was characterized by N2 adsorption–desorption, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy to examine the physical and chemical properties. The activity tests were performed with the steam, with water/ethanol molar ratio ranging from 2:1 to 15:1, the N2 flow rate from 20 to 120 mL min−1 to determine the space-time, and the temperature range from 623 to 923 K on the two different Ni source catalysts. A favorable operating condition was established at 823 K using water/ethanol = 6 molar ratio and carrier gas (N2) flow of more than 50 mL min−1 for nickel nitrate source, but for nickel sulfamate source, the optimum temperature changed to 773 K and other conditions were the same as for the nickel nitrate source. After eliminating the influence of internal and external diffusion factors, an empirical power-law kinetic rate equation was derived from the experimental data. The non-linear regression method was used to estimate the kinetic parameter. The activation energy of the catalyst was then calculated, and the supported nickel nitrate and nickel sulfamate catalysts were 25.345 and 41.449 kJ mol−1, respectively, which was in agreement with the experimental and model-predicted results.

Morphology and Microhardness of Nickel Electroformed under Vacuum-Degassing Conditions

Ni deposits were prepared from a nickel sulfamate type electrolyte bath under vacuum-degassing and temperature-gradient conditions without any additives. Morphology and microhardness of the deposits obtained at the current density of 1A/dm2, 3A/dm2, 5A/dm2 and 7A/dm2 were examined and analyzed. Experimental results showed that the deposits obtained under vacuum-degassing and temperature-gradient conditions exhibited fewer pinhole defects and finer grain size comparing with those formed under conventional deposition conditions, and that the microhardness of the deposits was greater than that from conventional deposition conditions without additives while lower than that from conventional deposition conditions with additives. Under the vacuum-degassing conditions, the electroforms had remarkably smoother surface with fewer void defects and finer grain size, and considerably microhardness.

Synthesis and Characterization of Nanoparticulate Strengthened Nickel Microcomponents

In this study, microcomponents of nickel (Ni) based nanocomposite were obtained by electrochemical co-deposition of Ni and alumina (Al2O3) nanoparticles into the microfabricated photoresist moulds from a nickel sulfamate bath with the presence of multi-wall carbon nanotubes (MWCNTs). The examination of dispersion behaviour of Al2O3 nanoparticles in nickel sulfamate bath with MWCNTs showed that the surfaces of the fillers are positively charged in a wide range of pH value, which favours the co-deposition of Al2O3 nanoparticles and MWCNTs with Ni. Results of SEM and EDX characterizations showed that the Al2O3 nanoparticles were uniformly distributed in the Ni matrix and their contents were improved with the presence of MWCNTs in the solution. It was also found that the mechanical properties of Ni were enhanced by the nanoparticulates in the Ni matrix.