Pyrolysis gas chromatogram

The pyrolysis gas chromatogram of ABS at 550°C changes considerably when the pyrolysis products are passed over zeolite catalysts. The specific activity towards certain reactions, e.g., cycliza-tion, aromatization, or chain cleavage is somewhat dependent on the nature of the individual zeolite. In general, enhanced benzene, toluene, ethylbenzene at the cost of dimer, trimer formation is observed. Nitrogen containing compounds do not appear in the pyrolysis oil after catalytic conversion. However, the product gas is rich in nitriles (132). 

Partial pyrolysis-gas chromatograms of representative immature kerogens or coals from the four sequences studied are shown in Figure 2. The abundance of thiophenes relative to aliphatic and aromatic hydrocarbons in the partial FID chromatograms differs markedly for the four samples shown. This is reflected by the ratio of the peak area of 2,3-dimethylthiophene relative to those due to 1,2-dimethylbenzene and n-non-l-ene (Le. TR = [2,3-dimethylthiophene]/[l,2-dimethylbenzene+n-non-... 

Fig. 3 Curie-point pyrolysis gas chromatogram of the non-extractable residue of a Teltow Canal sediment (Curie-point temperature 510° C).

It is our intention to make a mass spectrometric atlas of geological and archaeological ambers and other resins. This atlas will contain a high resolution pyrolysis gas chromatogram, the El and Cl pyrolysis mass spectra and relevant Py-GC/MS data on the... 

Pyrolysis gas chromatograms (PGC) were obtained on a model AIOOC Wilkens Aerograph gas chromatograph equipped with a Leeds and Northrup Speedomax G Recorder. The copper chromatography column was packed with acid washed chromosorb W and 20% SE-20. Pyrolysis was accomplished by placing a small, dry sample of polymer on a Rh-W, code 13-002, Gow-Mac coil and pyrolyzing for a predetermined time. 

Many studies on the identification of polymer additives by Py-GC/MS have been published recently for example, an innovative method based on direct analysis of polymers containing polymeric hindered amine light stabilizers (HALS) by using pyrolysis coupled to GC/MS was applied successfully for fast and straightforward identification of these additives. Each of the HALS showed different pyrolysis gas chromatograms containing characteristic pyrolysis products. As a result, HALS additives with very similar chemical structures, e.g., Chimassorb 944 and Chimassorb 2020, could be distinguished. 

Figure 9.1 Pyrolysis gas chromatograms of (a) a newly formulated adhesive, (b) a wellperforming adhesive and (c) a failed adhesive showing resolution of internal standard and...

FIGURE 13.2 Thermal extraction, open-system, and closed-system pyrolysis gas chromatograms of the oil-prone coal from the Heathfield-1 Well using the MSSV (microscaled seal vessel pyrolysis) method (see References 12 and 13) m = methylcyclohexane, n-alkanes (alkenes) indicate carbon number. 

The major mechanism of producing oligomers with pyrolysis can be attributed to thermal degradation. The intensity of the various oligomer peaks in a pyrolysis gas chromatogram will reflect the monomeric sequence and polymer structure when the formation of pyrolysis products is proportional to their existence in the copolymer. 

The intensity of the various dimer and trimer peaks in a pyrolysis gas chromatogram reflect the monomer sequence. 

Fig. 2.27. Pyrolysis-gas chromatograms of newly formulated adhesive (a), a well-performing adhesive (b) and a failed adhesive (c) showing resolution of internal standard and BHT peaks. After Franich et al. [631]. From R.A. Franich et al. Analyst 120, 1927-1931 (1995). Reproduced by permission of The Royal Society of Chemistry.

May et aP have used this Curie point filament pyrolyser to produce pyrolysis -gas chromatograms for various polymers (Method 106). 

Figure 1.2 (A) Filament pyrolysis - gas chromatogram of PVC (a) biphenyl, (b) methyl naphthalene, (c) naphthalene, (d) methylindene, (e) tetralin, (f) methyl indene, (g) indene, (h) indane, (i) styrene, (j) o-xylene, (k) ethylbenzene, (1) toluene, (m) benzene. (B) Filament pyrolysis - gas chromatography of polyvinylidene chloride, (a) tetra-chlorostyrene, (b) trichlorostyrene, (c) 1,3,5 trichlorobenzene, (d) w-dichlorobenzene, (e) trichlorobutadiene, (f) chlorobenzene, (g) vinyldene-chloride. [Source Author s own files)...

Figure 12.8 Mia ocolumn size exclusion chromatogram of a styrene-aaylonitrile copolymer sample fractions ti ansfeired to the pyrolysis system are indicated 1-6. Conditions fused-silica column (50 cm X 250 p.m i.d.) packed with Zorbax PSM-1000 (7p.m 4f) eluent, THF flow rate, 2.0 p.L/min detector, Jasco Uvidec V at 220 nm injection size, 20 nL. Reprinted from Analytical Chemistry, 61, H. J. Cortes et al, Multidimensional chromatography using on-line microcolumn liquid chromatography and pyrolysis gas chromatography for polymer characterization , pp. 961 -965, copyright 1989, with peimission from the American Chemical Society.

Figure 12.9 Typical pyrolysis chromatogram of fraction from a styrene-acTylonitiile copolymer sample obtained from a miciocolumn SEC system 1, acrylonitrile 2, styrene. Conditions 5 % Phenylmetliylsilicone (0.33 p.m df) column (50 m X 0.2 mm i.d.) oven temperature, 50 to 240 °C at 10 °C/min carrier, gas, helium at 60 cm/s flame-ionization detection at 320 °C make-up gas, nitrogen at a rate of 20 mL/min. P indicates tlie point at which pyrolysis was made. Reprinted from Analytical Chemistry, 61, H. J. Cortes et ai, Multidimensional cliromatography using on-line microcolumn liquid cliromatography and pyrolysis gas cliromatography for polymer characterization , pp. 961-965, copyright 1989, with permission from tlie American Chemical Society.

Figure 2.2 shows the total ion current trace and a number of appropriate mass chromatograms obtained from the pyrolysis gas chromatography-mass spectrometry analysis of the polluted soil sample. The upper trace represents a part of the total ion current magnified eight times. The peak numbers correspond with the numbers mentioned in Table 2.1 and refer to the identified compounds. The identification was based on manual comparison of mass spectra and relative gas chromatographic retention times with literature data [34, 35] and with data of standards available. In some cases unknown compounds were tentatively identified on the basis of a priori interpretation of their mass spectra (labelled tentative in Table 2.1). 

Fig. 11.4 shows the total ion current trace and some mass chromatograms obtained by flash evaporation pyrolysis gas chromatography-mass spectrometric analysis of the polluted sediment sample. All compounds present in this complex mixture were not listed. A selection was made to exemplify several aspects of the screening approach. The peak number correspond with the numbers in Table 11.1. Identifications were based on the same criteria as mentioned above. Although several components were shown to be real pyrolysis products, all the compounds are present as such in the sample and resulted from simple thermal extraction from the wire. This was shown in separate analyses using ferromagnetic wires with a Curie temperature of 358°C. 

Figure 6. Partial gas chromatograms of vacuum pyrolysis tars. The shaded peaks are compounds derived from triterpenes.

A number of multidimensional analyses have been developed that provide powerful methods for characterizing these polymers. Linking a liquid chromatogram to a pyrolysis gas chromatograph [l 9] can determine the breadth of the composition distribution, as the method fractionates the SAN copolymer before pyrolysis. This information is useful for determining the source of variation in SAN copolymer properties. Composition drift towards high acrylonitrile-containing fractions can lead to undesirable yellow color, and excessively broad composition drift can cause opacity and brittleness in the material due to phase separation... 

Pyrolysis of polystyrene produces an oil very high in concentration of the monomer, styrene and also other aromatic compounds. Eigure 11.15 shows a typical gas chromatogram for the pyrolysis oil produced from the pyrolysis of polystyrene, showing... 

The amounts of produced hydrocarbons widi a branched cliain do not overwhelm diose with a normal chain. Assuming that sensitivities in analyses for hydrocarbons of the same catbon number (n) remain identical, the molar ratio of branched Cn/nonnal C can be calculated from respective peak areas on the gas chromatogram. The estimated values were less than 1.5. In contrast, the ratio was more than 5 (4-metiiyl octane/n-nonane) in the pyrolysis experiment by Domine [160]. The pyrolysis tliat proceeds sluggishly under a high-pressure condition prefers the formation of branched hydrocarbons to tiiat of normal ones, probably because of the small molar volume of tiie former. Thus, tiiis experiment demonstrates that some mechanism different from that in pyrolysis is involved in the shock process for an instant. 

A direct pyrolysis-gas chromatography of the kerogens was also performed and is presented in Figure 7 (9). The chromatograms taken at pyrolysis temperature of 475°C show the total distribution of hydrocarbons, with the relative importance of long-chain molecules up to C30 in types I and III. It also shows the importance of low-boiling aromatics (B benzene T toluene ... 

Gas chromatograms of volatile pyrolysis products formed from plasma-polymerized HMCTSN and HMCTSO are shown in Figs. 1 and 2, respectively. They were identified by mass spectrometry and with the aid of certain standard compounds. For the sake of brevity it is not possible to discuss the mass spectra here. The structures of pyrolysis products corresponding to the respective chromatographic peaks are presented in Table I for both polymers. It should be noted that the peaks marked by X (Figs. 1 and 2) correspond to unseparated mixture of light hydrocarbons. As can be seen from Table I, the pyrolysis products in the case of both polymers consist of low molecular cyclic organosilicon compounds. 

Figure 1. Gas chromatogram of the volatile cyclic products of pyrolysis at 400°C of plasma-polymerized hexameth-ylcyclotrisilazane...

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