Preparation of carbon nanotubes using cvd CVD method

In this work preparation and characteristic of modified nanocarbons is described. These materials were obtained using nanocrystalline iron as a catalyst and ethylene as a carbon source at 700°C. The influence of argon or hydrogen addition to reaction mixture was investigated. After ethylene decomposition samples were hydrogenated at 500°C. As a results iron carbide (Fe3C) in the carbon matrix in the form of multi walled carbon nanotubes was obtained. After a treatment under hydrogen atmosphere iron carbide decomposed to iron and carbon and small iron particles agglomerated into larger ones

Thermal and mechanical properties of polyamide 12/modified carbon nanotubes composites prepared via the in situ ring-opening polymerization

In this study polyamide 12 (PA12) based composites prepared in situ via an ring-opening polymerization of lauryl lactam in the presence of raw and functionalized carbon nanotubes (CNTs) are characterized. This method has been widely applied for thermoplastic based composites, resulting in materials with relatively small amounts and uniform nanofiller distribution. The effect of multi-wall carbon nanotubes chemically modified with hydroxyl or amine groups on PA12 matrix is discussed in terms of the phase structure, thermal, mechanical, and water vapor barrier properties as well as the state of CNTs dispersion in composites. The obtained results confirm, that in general the physical properties of PA12 are noticeably affected by the presence of 0.35 wt % CNTs, whilst the benefits from nanotubes modification are observed in changes of phase transition temperatures and composite mechanical performance, whilst the thermooxidative stability and water absorption the CNTs chemical modification is less pronounced.Określono właściwości kompozytów na osnowie poliamidu 12 (PA12), napełnionych niemodyfikowanymi lub modyfikowanymi nanorurkami węglowymi (CNTs), otrzymanych in situ w polimeryzacji z otwarciem pierścienia. Metoda ta, szeroko stosowana do wytwarzania kompozytów na osnowie termoplastów, daje możliwość uzyskania materiałów o względnie małej zawartości i jednorodnej dyspersji nanonapełniacza. Omówiono wpływ modyfikacji wielościennych nanorurek węglowych grupami hydroksylowymi lub aminowymi na strukturę fazową, właściwości termiczne, mechaniczne i barierowe osnowy poliamidowej oraz na stopień dyspersji nanocząstek w kompozycie. Wyniki badań potwierdziły wpływ dodatku 0,35 % mas. nanorurek na właściwości fizyczne PA12, przy czym korzyści wynikające z modyfikacji chemicznej obserwowano w wypadku temperatury przemian fazowych oraz wytrzymałości mechanicznej kompozytów, natomiast w odniesieniu do stabilności termooksydacyjnej i właściwości barierowych wpływ funkcjonalizacji był mniejszy

Termiczne i mechaniczne właściwości kompozytów poliamid 12/modyfikowane nanorurki węglowe otrzymanych in situ metodą polimeryzacji z otwarciem pierścienia

In this study polyamide 12 (PA12) based composites prepared in situ via an ring-opening polymerization of lauryl lactam in the presence of raw and functionalized carbon nanotubes (CNTs) are characterized. This method has been widely applied for thermoplastic based composites, resulting in materials with relatively small amounts and uniform nanofiller distribution. The effect of multi-wall carbon nanotubes chemically modified with hydroxyl or amine groups on PA12 matrix is discussed in terms of the phase structure, thermal, mechanical, and water vapor barrier properties as well as the state of CNTs dispersion in composites. The obtained results confirm, that in general the physical properties of PA12 are noticeably affected by the presence of 0.35 wt % CNTs, whilst the benefits from nanotubes modification are observed in changes of phase transition temperatures and composite mechanical performance, whilst the thermooxidative stability and water absorption the CNTs chemical modification is less pronounced.Określono właściwości kompozytów na osnowie poliamidu 12 (PA12), napełnionych niemodyfikowanymi lub modyfikowanymi nanorurkami węglowymi (CNTs), otrzymanych in situ w polimeryzacji z otwarciem pierścienia. Metoda ta, szeroko stosowana do wytwarzania kompozytów na osnowie termoplastów, daje możliwość uzyskania materiałów o względnie małej zawartości i jednorodnej dyspersji nanonapełniacza. Omówiono wpływ modyfikacji wielościennych nanorurek węglowych grupami hydroksylowymi lub aminowymi na strukturę fazową, właściwości termiczne, mechaniczne i barierowe osnowy poliamidowej oraz na stopień dyspersji nanocząstek w kompozycie. Wyniki badań potwierdziły wpływ dodatku 0,35 % mas. nanorurek na właściwości fizyczne PA12, przy czym korzyści wynikające z modyfikacji chemicznej obserwowano w wypadku temperatury przemian fazowych oraz wytrzymałości mechanicznej kompozytów, natomiast w odniesieniu do stabilności termooksydacyjnej i właściwości barierowych wpływ funkcjonalizacji był mniejszy

The Kinetics of Ethylene Decomposition on Iron Catalyst

The effect of ethylene partial pressure and temperature on the hydrocarbon decomposition rate was studied. As a catalyst, a triply promoted iron catalyst (with addition of small amounts of potassium, calcium and alumina oxides) was used. The mean crystallites size was ca. 17 nm. The processes were performed using pure ethylene or ethylene-nitrogen mixture under atmospheric pressure at the temperature range from 400 to 460°C. The growth of carbon mass as a function of reaction time was measured using a thermobalance. The phase composition of the samples after ethylene decomposition was determined using X-ray diffraction technique. The reaction rate was independent of ethylene partial pressure in the range from 0.25 to 1 bar. The maximal carbon yield for given experimental conditions was estimated

Decomposition of ethylene on iron catalyst to obtain carbon nanotubes and the way of their purification

This paper describes preparation and characterization of carbon nanotubes obtaining using ethylene as a carbon source and iron as catalyst. Additionally purification procedure of carbon nanomaterials is presented. Purification was conducted in two stages. In the first one hydrogen or air was used in order to gasify unwanted carbon forms. In the second one - various reactants (nitric, hydrochloric or nitro-hydrochloric acids) were applied to remove metal particles. Obtained materials were characterized using X-ray diffraction, transmission electron microscopy and thermogravimetry

Removal of SO2 from gases on carbon materials

The aim of the work is to describe a capability of the active carbon CARBON L-2-4 (AC) and of the nanocarbon (NC) materials containing iron nanoparticles to continuously remove SO2 from air. The carbon nanomaterials (NC) containing iron nanoparticles were synthesised using a chemical vapor deposition method - through catalytic decomposition of ethylene on nanocrystalline iron. The process of SO2 removal was carried out on dry and wet with water carbon catalyst (AC or NC) and was studied for inlet SO2 concentration 0.3 vol.% in the presence of O2, N2 and H2O, in the temperature range of 40-80°C

Preparation and characterization of multi-walled carbon nanotubes grown on transition metal catalysts

Transition metal catalysts (mainly: iron, cobalt and nickel) on various supports are successfully used in a largescale production of carbon nanotubes (CNTs), but after the synthesis it is necessary to perform very aggressive purification treatments that cause damages of CNTs and are not always effective. In this work a preparation of unsupported catalysts and their application to the multi-walled carbon nanotubes synthesis is presented. Iron, cobalt and bimetallic iron-cobalt catalysts were obtained by co-precipitation of iron and cobalt ions followed by solid state reactions. Although metal particles were not supported on the hard-to-reduce oxides, these catalysts showed nanometric dimensions. The catalysts were used for the growth of multi-walled carbon nanotubes by the chemical vapor deposition method. The syntheses were conducted under ethylene - argon atmosphere at 700°C. The obtained catalysts and carbon materials after the synthesis were characterized using transmission electron microscopy (TEM), X-ray diffraction method (XRD), Raman spectroscopy and thermogravimetric analysis (TG). The effect of the kind of catalyst on the properties of the obtained carbon material has been described

Preparation and characterization of multi-walled carbon nanotubes grown on transition metal catalysts

Transition metal catalysts (mainly: iron, cobalt and nickel) on various supports are successfully used in a largescale production of carbon nanotubes (CNTs), but after the synthesis it is necessary to perform very aggressive purification treatments that cause damages of CNTs and are not always effective. In this work a preparation of unsupported catalysts and their application to the multi-walled carbon nanotubes synthesis is presented. Iron, cobalt and bimetallic iron-cobalt catalysts were obtained by co-precipitation of iron and cobalt ions followed by solid state reactions. Although metal particles were not supported on the hard-to-reduce oxides, these catalysts showed nanometric dimensions. The catalysts were used for the growth of multi-walled carbon nanotubes by the chemical vapor deposition method. The syntheses were conducted under ethylene - argon atmosphere at 700°C. The obtained catalysts and carbon materials after the synthesis were characterized using transmission electron microscopy (TEM), X-ray diffraction method (XRD), Raman spectroscopy and thermogravimetric analysis (TG). The effect of the kind of catalyst on the properties of the obtained carbon material has been described

High Pressure Synthesis versus Calcination – Different Approaches to Crystallization of Zirconium Dioxide

Calcination and microwave-assisted hydrothermal processing of precipitated zirconium dioxide are compared. Characterization of synthesized products of these two technologies is presented. The infiuence of thermal treatment up to 1200oC on the structural and spectroscopic properties of the so-obtained zirconium dioxide is examined. It was found that initial crystallization of material inhibits the crystal growth up to the 800oC (by means of XRD and TEM techniques), while the material crystallized from amorphous hydroxide precursor at 400oC, exhibits 26 nm sized crystallites already. It was found using the TG technique that the temperature range 100–200oC during the calcination process is equivalent to a microwave hydrothermal process by means of water content. Mass loss is estimated to be about 18%. Based on X-ray investigations it was found that the initial hydroxide precursor is amorphous, however, its luminescence activity suggests the close range ordering in a material

Photoluminescence and Chromaticity Properties of ZnO Nanopowders Made by a Microwave Hydrothermal Method

Four series of ZnO nanopowders obtained by a microwave hydrothermal method are examined. Two different solvents (ethanol and distilled water) and different values of pressure during heating in the reactor were used. The obtained nanopowders show a bright emission covering visible light spectral region, including the band edge emission. Results of scanning electron microscopy, X-ray diffraction, photo- and cathodoluminescence investigations and also CIE1961 chromaticity diagram are presented