Sealed vessel pyrolysis

Berwick, L., Greenwood, P., Kagi, R., and Croue, J. P. (2007). Thermal release of nitrogen organics from natural organic matter using micro scale sealed vessel pyrolysis. Org. Geochem. 38,1073-1090. 

Sealed vessel pyrolysis is another pyrolysis type that is performed in furnace type pyrolysers. In this type of pyrolysis, the sample is heated for a relatively long period of time, in a sealed vessel, generally at relatively low temperature (below 350° C). The pyrolysis products are further analyzed, commonly by off-line procedures (GC, GC/MS, FTIR, etc). The technique allows the pyrolysis to be performed for as long as months and to use different atmospheres (inert or reactive) [17a]. The procedure is not used only as an analytical tool, and it can be seen as a preparative pyrolysis technique. 

A variety of pyrolytic techniques were applied for the analysis of kerogens [19]. One of these techniques is the sealed vessel pyrolysis where the sample is heated for relatively long periods of time In a sealed vessel and the pyrolytic products analyzed off-line by conventional analytical techniques (GC, GC/MS, FTIR, etc.) [36]. Another technique is bulk flow pyrolysis in which the whole sample is pyrolysed at constant or in gradient temperature in a gas flow with on-line monitoring of the evolving volatiles [37]. This technique is closer to a thermal method of analysis than pyrolysis. 

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. 

Artificial Maturation. Laboratory maturation studies provide a means to determine the influence of temperature on kerogen composition, since other variables (e.g. source input) can be eliminated. In order to study the behaviour of organically bound sulfur under these controlled conditions, Py-GC-FID/FPD was performed on a suite of solvent-extracted residues from sealed vessel (hydrous pyrolysis) experiments aimed at simulating maturation over the range involved in petroleum generation. 

Figure 4.7.1. The variation in chromatographic peak heights for n-alkanes generated from torbanite pyrolysed by several techniques [35] A - laser micropyrolysis, B - sealed vessel microscale furnace pyrolysis, C - resistiveiy heated pyrolysis (HP 18580 A Pyroprobe), and D - microfurnace pyrolysis (SGE Pyrojector).

In related work, the ammonium salts [NH4][MF5] (M = Zr, Hf) have been prepared via oxidation of the metal with [NH4] [HF2], followed by pyrolysis in a sealed vessel.626 Analysis of single crystals revealed that the structure is isotypic to TlZrF5. 

Chloropentafluoro-, 1,1-dichlorotetrafluoro-, and l,l-dichlorotrifluoro(trifluoro-methyl)-cyclopropane[(12a), (12b), and (21) (seepp. 15, 19), respectively] decompose cleanly at 210,156, and 170 °C, respectively, at pressures of 1 atm or below in sealed vessels with release of singlet difluorocarbene and formation of the appropriate olefin [in the case of (12a),theCFa CFCl formed undergoes extensive dimerization to l,2-dichlorohexafluorocyclobutane]. Pyrolysis of 1,1,2-trichlorotrifluoro-cyclopropane (12d) in glass at 200 °C (1.1 atm) proceeds with ejection of both difluorocarbene (mainly) and, it seems, chlorofluorocarbene since 1,1 -dichlorodifluoro-... 

Fig.4.3. Experimental arrangement for investigation of pyrolysis of molecules by the method of semiconductor sensors 1 - reaction vessel, 2 - quartz slab with a ZnO film (sensor), 3 - filter, 4 - contacts, 5 - incandescent filament, 6 - thermocouple, 7 - cell with a substance, 8 - lamp - manometer, 9 - pin, 10 - flask, 11 - sealing bulkhead, 12 - trap, 13 - thermostat.

As mentioned earlier, a number of different types of reactors have been tried in tire pyrolysis. Almost any vessel that can be sealed can be used as a pyrolysis reactor. Reactor design has a significant effect on the quality of char produced, due to a uniform temperature gradient, and the abrasion of the particles with one another. Some of the reactor types that have been used are ... 

Vessels are loaded with terrestrial cellulose, lake sediment cellulose, or water and graphite (as a carbon source) and sealed in an argon atmosphere, followed by heating (pyrolysis) at 1050 °C in an evacuated quartz tube. The addition of an encapsulating quartz tube has been incorporated to prevent repeated oxidation of the outer nickel surface and to simplify the cleaning procedure. Heating has been increased from 950 °C used in the original experiments to 1050 °C to account for the insulation of the quartz tube (see Motz et al, 1997). 

Clean the interior of vessel using a stainless steel brush (1/4" diameter). Gently tap out debris. Care must be taken not to score the raised circular seats at the opening of the vessel as this will result in a poor seal and loss of gas during pyrolysis. 

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