Walerian Arabczyk

Preparation of nanocrystalline iron-carbon materials as fillers for polymers

This paper presents a method of preparing nanocrystalline iron–carbon materials which can be applied as fillers for polymers. Nanocrystalline iron samples were carburized either under ethylene/hydrogen mixture or under pure ethylene. Three kinds of samples were prepared: cementite/carbon (Fe3C/C), iron/cementite (Fe/Fe3C) and iron/carbon (Fe/C) ones. After carburization the samples were characterized using XRD and SEM methods. The obtained samples of iron–carbon nanoparticles were applied as fillers to polymer nanocomposites prepared in a polycondensation reaction (in situ) in a poly(ether-ester) matrix. The nanofillers were dispersed in monomers (diols) using a sonificator and a high-speed rotary stirrer. The obtained nanocomposites were characterized as regards their structure (SEMxa0method) and mechanical behaviour.

Utilization of spent iron catalyst for ammonia synthesis

Utilization of spent iron catalyst for ammonia synthesis Several methods of the utilization of spent iron catalyst for ammonia synthesis have been presented. The formation of iron nitrides of different stoichiometry by direct nitriding in ammonia in the range of temperatures between 350°C and 450°C has been shown. The preparation methods of carbon nanotubes and nanofibers where iron catalyst catalyse the decomposition of hydrocarbons have been described. The formation of magnetite embedded in a carbon material by direct oxidation of carburized iron catalyst has been also presented.

Study of the kinetics of carburisation and nitriding of nanocrystalline iron

In the course of nitriding process of nanocrystalline iron that was promoted with aluminium and calcium oxides, nitrides such as Fe4N and Fe3–2N were created. In the process of carburisation, carbide Fe3C was created. The nanocrystalline iron nitriding and carburisation process rate was studied making use of the flow differential tubular reactor with thermogravimetric measurement of mass changes. Nitriding and carburisation process rates were limited by dissociative adsorption rate on the surface of iron and were dependent on the crystallite surface to crystallite volume ratio. Assuming the adsorption is the rate limiting step, the numerical simulations were performed. Theoretical considerations were compared with the experimental results of the iron nitriding or carburisation reaction. Kinetics and thermodynamic parameters of nitriding and carburisation were determined.