Oxidation kinetics of nickel nano crystallites obtained by controlled thermolysis of diaquabis(ethylenediamine)nickel(II) nitrate

Abstract

The metal complex, [Ni(en) 2 (H 2 O) 2 ](NO 3 ) 2 (en = ethylenediamine), was decomposed in a static furnace at 200°C by autogenous decomposition to obtain phase pure metallic nickel nanocrystallites. The nickel metal thus obtained was studied by XRD, IR spectra, SEM and CHN analysis. The nickel crystallites are in the nanometer range as indicated by XRD studies. The IR spectral studies and CHN analyses show that the surface is covered with a nitrogen containing species. Thermogravimetric mass gain shows that the product purity is high (93%). The formed nickel is stable and resistant to oxidation up to 350°C probably due to the coverage of nitrogen containing species. Activation energy for the oxidation of the prepared nickel nanocrystallites was determined by non-isothermal methods and was found to depend on the conversion ratio. The oxidation kinetics of the nickel crystallites obeyed a Johnson-Mehl-Avrami mechanism probably due to the special morphology and crystallite strain present on the metal.

Synthesis of Highly Dispersed Nanosized NiO/MgO-Al2O3 Catalyst for the Production of Synthetic Natural Gas with Enhanced Activity and Resistance to Coke Formation

“…Metal precursor distribution on S1 support surface was, therefore, more uniform due to the higher surface area of support and more accessible surface area within the pores. Furthermore, the splitting of the crystals during the exothermic combustion of the ligands by nitrates during the thermal treatment prior to reduction , would also lead to the formation of highly dispersed NiO nanoparticles (in agreement with XRD results) with moderate interaction with the support for S1N2en catalyst. A question that remains is whether similar results could be achieved by using an alumina support with a wider pore size distribution containing larger diameter pores.…”

“…As indicated earlier, calcination is carried out in a muffle furnace in static air atmosphere with the catalyst placed in a lidded crucible to avoid air flow over the catalyst. Therefore, ethylenediamine ligands are partially decomposed by nitrate ions . The nitrates that are also grafted on alumina have not chemically reacted, and, at higher temperatures, they react with the ligands and destroy them by oxidation .…”

“…Therefore, ethylenediamine ligands are partially decomposed by nitrate ions. 55 The nitrates that are also grafted on alumina have not chemically reacted, and, at higher temperatures, they react with the ligands and destroy them by oxidation. 54 The results indicate that using [Ni(en) 2 (H 2 O) 2 ](NO 3 ) 2 as catalysts precursor leads to lower reduction temperature.…”

Novel preparation of highly photocatalytically active copper chromite nanostructured material via a simple hydrothermal route

“…The band located at 1043 cm -1 is attributable to the C–N stretching vibration. The band at 475 cm -1 is corresponding to ν (Cu–N) vibration [ 22 ]. FT-IR spectrum of the chromium source is seen in Fig 2B .…”

Solid oxide cell electrolytes deposited by atmospheric suspension plasma spraying at high velocity and high temperature

“…It is noteworthy to reiterate that all as-sprayed sample permeabilities reported here are with fuel electrodes in the fully oxidized state. Given that oxidation of Ni initiates at approximately 320 • C [48], this approach was chosen to avoid oxidation and expansion of Ni metal during YSZ deposition at 900-1000 • C. In the case where the fuel electrodes lack large pinhole defects, reducing the fuel electrode would in theory have a measurable effect on the overall leak rate of a full cell. In contrast, if the fuel electrode contains a number of large pinholes that serve as the primary gas flow pathways, then reducing the fuel electrode would have a negligible effect on measured full-cell leak rates.…”