IR pyrolysis

TG-FT-IR, Pyrolysis analyses were performed on the preliquefaction solids using thermogravimetric (TG) analysis with on-line analysis of the evolved products (including an infrared spectrum of the condensables) by FT-IR. The TG-FTIR method has been described previously (23-25). The Bomem TG/plus instrument was employed. A sample is continuously weighed while it is heated. A flow of helium sweeps the products into a multi-pass cell for FT-IR analysis. Quantitative analysis of up to 20 gas species is performed on line. Quantitation of the tar species is performed by comparison with the balance reading. 

Abstract. IR pyrolysis of PAN and PAN based composites yields ordered graphitelike structure as well as several carbon nanostructures. Metal-carbon nanocomposites, in which the nanosized metal particles were introduced into the structure of carbon matrix in the course of IR pyrolysis of composite-precursor on the basis of PAN and metal (Gd, Pt, Ru, Re) compounds were prepared. The carbon phase of metal-carbon nanocomposites was shown to include different types of nano structured carbon particles. Bamboo-like CNT were observed in the structure of pyrolized at 910 and 1000°C composite-precursor based on PAN and GdCl3. At T=1200°C the solid carbon spheres with diameter in the range of 50-360 nm and octahedral carbon particles with the size in the range of 300-350 nm were observed. These nanostructured particles consist of carbon only or they include Gd nanoparticles incapsulated in carbon shell. IR pyrolysis of composite-precursor based on PAN as well as H2PtCl6 and RuC13 or NH4Re04 (Pt Ru(Re)=10 l) allows the preparation of Pt-Ru and Pt-Re alloys nanoparticles with 2[Pg.577]

Keywords polyacrylonitrile, IR pyrolysis, graphite, carbon nanotubes, nanostructured carbon, transmission electron microscopy... 

This study shows the possibilities and specific feature of IR-pyrolysis for the formation of nanostructured carbon. In such way PAN, thermal transformations of which have been studied in detail [8-11], was chosen as the precursor for preparation of nanostructured carbon materials by carbonization of PAN and its composites with gadolinium chloride under non-coherent IR radiation. Specific action of IR-radiation on vibrational energy of PAN bands macromolecules allows one to decrease extremely time treatment and as a result to make simple, low energy and cost-effective pyrolitic method. 

Chemical reactions proceeding in the system under the conditions of IR pyrolysis result in the changes of PAN crystalline structure. X-ray phase analysis (XRPA) has shown that at T>200°C in the course of formation of ordered carbon structures crystalline and amorphous phases of initial PAN disappear, while another amorphous carbon phases appear [12] ... 

Including into initial PAN solution metal compounds provides the formation of metal-carbon nanocomposites. The nanosized metal particles were introduced into the structured carbon matrix in the course of IR pyrolysis of composite-precursor on the basis of PAN and compounds of corresponding metals. In this way carbon composites containing nanosized Gd particles (4Efficient reduction of metal takes place in the course of IR pyrolysis of composite-precursor with participation of hydrogen, which is released in dehydrogenation of main polymeric chain of PAN. 

In the course of IR pyrolysis, according to mass spectrometry and gas chromatography data, various gas products of destruction of PAN polymeric chain are present in the reaction chamber, including hydrocarbons such as ethylene and propylene [17, 18], These hydrocarbons provide the carbon source. Catalytic decompositions of hydrocarbons at high intensity IR-radiation in the presence of metallic Gd leads to the formation of carbon nanostructures such as observed bamboo-like CNT. It is well known that Ni, Co Fe have conventionally been used widely as metallic catalysts for high temperature pyrolysis of hydrocarbons. Recently bimetallic components was shown to be more effective than single metals as catalysts. Especially transition metals with addition of rare-earth metals such as Y, Ce, Tb, La and Ho [19]. In this work catalytic activity of single metallic Gd in the IR-pyrolysis of hydrocarbons are found by us for the first time. 

Metal-carbon nanocomposites containing bimetallic nanosized Pt-Ru (Pt-Re) particles were prepared in the course of IR-pyrolysis composite-precursor containing PAN as well as H2PtCl6 and RuCL, (or NFEReCA) in the ratio Pt Ru (Re) = 10 1. 

IR pyrolysis of PAN and PAN based composites yields ordered graphite-like structure as well as several carbon nanostructures, which were studied by means of Raman spectroscopy, XRD, including XRPA and TEM. The interlayer distance in graphite-like phase decreases and crystallite size grows with irradiation intensity... 

IR-pyrolysis of composite-precursor based on PAN as well as H2PtCl6 and RuC13 or NH4ReC>4 (Pt Ru(Re)=10 l) allows the preparation of Pt-Ru and Pt-Re alloys nanoparticles with 2carbon matrix. Such metal-carbon nanocomposites can se used as the possible catalyst material in fuel cells. 

The reduction of rhenium salt in a PAN matrix and the formation of the polyconjugated polymer system proceed simultaneously and interdependently during IR-pyrolysis of a film. As result the thin film of carbon with ultra dispersed metal particles is formed on a surface of porous support (Fig. 2). The thickness of defectless Re-containing carbon film was 300 - 500 nm. The size of metallic particles was proved to be from 3 to 10 nm. The average content of rhenium in a metal-carbon composition was about 5 mass %. 

The catalytic activity of membrane catalyst, obtained by IR-pyrolysis of PAN and ammonium perrhenate, was studied in the flow membrane reactor in a model reaction of cyclohexane dehydrogenation at the temperatures from 500 to 700 K. 

Chemical composition NMR, elemental analysis, UV-Vis, IR, pyrolysis-GC-mass spectrometry, MALDI-TOF, LILB ID-MS... 

The use of transmission IR, pyrolysis IR and pyrolysis GC to determine the polymer type of a plastic is covered in Section 2.1. Where appropriate standards are available, it is also possible to use IR to quantify the amounts of monomers in copolymers and terpolymers. 

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