Furnace pyrolyzer

A factor that must be considered with furnace pyrolyzers as well as with the other types of pyrolyzers is the achieving of short TRT values. A slow sample introduction in the hot zone of the furnace will end in a long TRT. A poor contact between the sample and the hot source may also lead to long TRT, most of the heat being transferred by radiation and convection and not by conduction. However, fairly short TRTs in furnace pyrolyzers were reported in literature [14, 15]. Also, in furnace pyrolyzers it is more common to see differences in the temperature between the furnace and the sample. Due to the poor contact between the sample and the hot source, the sample may reach a lower actual temperature than the temperature of the furnace wall. This may be the explanation why there were reported variations in the pyrolysis products in microfurnace systems as compared to the results obtained in inductively or filament heated pyrolyzers [16,17]. 

Other different models of furnace pyrolyzers were reported in literature [12]. As an example, a two-temperature zone furnace was made, and it was utilized to provide information about more volatile compounds trapped (adsorbed) in a sample as well as for performing true pyrolysis. In this system, the sample is heated first at 300° C where the volatile compounds are eliminated, and then the sample is pyrolyzed at 550° C. 

Concentration techniques in GC are used mainly for trace analysis. Pyrolysis commonly generates enough material for a GC analysis even when a very small amount of sample is taken for analysis. For this reason, concentration techniques are not frequently associated with Py-GC. However, for the analysis of specific traces in pyrolysates, the amount of material generated from a small sample is not always large enough. In these cases, it is more common to use pyrolyzers with larger sample capacity (such as furnace pyrolyzers) followed by the off-line processing of the pyrolysate. 

The reproducibility of the results for heated filament pyrolyzers and Curie point pyrolyzers as well as the comparison between the two systems was reported for a number of materials [41], The reproducibility of the analysis was evaluated both qualitatively and quantitatively. It was found that for most samples the results are obtained with very good reproducibility for the same instrument. However, differences in the instrumentation may play an important role regarding the dissimilarity of the results, even when they are operated at comparable parameters. These differences are typically less pronounced between filament pyrolyzers and Curie point pyrolyzers. Also, microfurnace pyrolyzers are closer to filament pyrolyzers than large furnace ones. On the other hand, laser micropyrolyzers or sealed vessel furnace pyrolyzers may lead to quite different results. 

In principle, rel. (4.2.1) allows the calibration of any pyrolyzer for a series of given temperatures with corresponding temperatures acquired by the sample. It is interesting, however, that a study regarding the pyrolysis of Kraton 1107 in a furnace pyrolyzer [3] found linearity between T and R only at temperatures between 450° C and 625° C. 

Wendlandt and Bradley (88, 89) have described an automated instrument which is capable of studying eight samples in a sequential manner. The samples are automatically introduced into the furnace, pyrolyzed to a preselected temperature limit, and then removed. After the furnace has cooied back to room temperature, the cycle is repeated. Operation of the sample-changing mechanism, furnace-temperature rise and cooling, recording, and so on is completely automatic. 

In order to pyrolyze samples rapidly for introduction to a gas chromatograph, furnace pyrolyzers are generally held isothermaUy at the desired pyrolysis temperature and the samples introduced into the hot volume. Carrier gas is generally routed through the furnace to remove the pyrolysate quickly from the pyrolysis zone to minimize secondary pyrolysis. 

Another approach has been developed by Shin Tsuge at the University of Nagoya in Japan. His furnace pyrolyzer includes a cool chamber where samples are loaded into a small crucible above the hot zone. Once the sample is in place, the cup is rapidly lowered into the furnace for pyrolysis. 

Because of their simple construction and operation, furnace pyrolyzers are frequently inexpensive and relatively easy to use. Since they are operated isothermally, there are no controls for heating ramp rate or pyrolysis time. The analyst simply sets the desired temperature and, when the furnace is at equilibrium, inserts the sample. Although this simplicity may lose its attractiveness as soon as the analyst requires control over heating rate or time, there are some experiments and sample types that capitalize on the design of a furnace. Liquid, especially gaseous samples, are pyro-lyzed much more easily in a furnace than by a filament-type pyrolyzer. Because filament pyrolyzers depend on applying a cold sample to the filament and then... 

Synthetic polyamides, or nylons, are widely exploited as libers, moldings, and films. The thermal degradation of a series of aliphatic polyamides was investigated by high-resolution Py-GC." Both lactam and diamine-dicarboxylic acid types of nylon samples were pyrolyzed at 550°C in a furnace pyrolyzer under a flow of nitrogen carrier gas, and the resulting degradation products were continuously separated by a capillary separation column. Table 5.3 summarizes the various classes of common... 

Depending on the heating mechanism, pyrolysis systems have been classified into two groups continuous-mode pyrolyzers (e.g., furnace pyrolyzer) and pulsemode pyrolyzers (e.g., heated filament. Curie point, and laser pyrolysis). All of them are extensively used in polymer characterization and degradation smdies. 

In Situ Methylation and Py-MS The sample (standards of known concentration or the cells to be analyzed) and 5 uL of 0.1 M tetramethylammonium hydroxide (TMAH) is added to the Curie-point wire and dried in hot air. The resulting dimethyl-DPA-coated wire is introduced in a quadrupole ion trap equipped with microtube furnace pyrolyzer capabilities, using a 200-460 C temperature ramping program. Alternatively, a triple quadrupole mass spectrometer may be employed using a Curie-point pyrolysis inlet with a 70 eV El source. Figure 19.6 shows the pyrolysis mass spectra of B. anthracis with and without in situ methylation obtained after a brief 10 min sample preparation and analysis from a 2.2 x 10 CFU sample. 

Wood components [122] Archaeological waterlogged wood (pine, elm, beech) of the Roman period Double-shot micro furnace pyrolyzer Py temperature 500°C... 

In the furnace pyrolyzer type, the sample is introduced into the center of a tubular furnace held at a fixed temperature. Temperature is controlled by a proportioning controller that utilizes a thermocouple feedback loop. 

Figures 2.1 and 2.2 illustrate the schematic flow diagrams of the measuring systems of the pyrolysis (Py)-GC/MS and evolved gas analysis (EGA)—MS, respectively. In both systems, the vertical micro-furnace pyrolyzer (Frontier Lab., PY-2020iD) mounted on...

Figure 2.1 Schematic flow diagram of Py-GC/MS System (from the upper to the lower flow), (a) Carrier gas 100 ml/min of He flow at the pyrolyzer, 1 ml/mln at the separation column through a splitter (1/ 100) (b) pyrolyzer a micro-furnace pyrolyzer (Frontier Lab., PY-2020ID) at 600 °C (c) pyrolyzer/GC interface temp. 320 °C (d) GC injection temp. 320 °C (e) sample size ca. 0.2 mg of a sample cup (ECO cup-L o.d. 4.2 x i.d. 4x8 mm height, deactivated stainless steel cup) (f) GC separation column Ultra ALLOY-5 (0.25 mm x 30 m 0.25 pm film of 5%diphenyl-95%dimethylpolysiloxane) (g) GC oven temp, programmed from 40 °C (2 min hold) - (20 °C/min) -320 °C (13 min hold) (h) GC/MS adapter (Frontier Lab, Vent-free adapter) (i) GC/MS interface temp. 320 °C (j) El source (70 eV) temp. 230 °C (k) MS, scan range 29-600 (m/z) at 2000 amu/sec.

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