Pyrolysis monitoring

The pyrolysis of CR NH (<1 mbar) was perfomied at 1.3 atm in Ar, spectroscopically monitoring the concentration of NH2 radicals behind the reflected shock wave as a fiinction of time. The interesting aspect of this experiment was the combination of a shock-tube experiment with the particularly sensitive detection of the NH2 radicals by frequency-modulated, laser-absorption spectroscopy [ ]. Compared with conventional narrow-bandwidth laser-absorption detection the signal-to-noise ratio could be increased by a factor of 20, with correspondingly more accurate values for the rate constant k T). 

Journal of Analysis and Applied Pyrolysis Journal of Chromatographic Science Journal of Chromatography Journal of Environmental Monitoring Journal of Liquid Chromatography Journal of Mass Spectrometry... 

Mixtures can be identified with the help of computer software that subtracts the spectra of pure compounds from that of the sample. For complex mixtures, fractionation may be needed as part of the analysis. Commercial instmments are available that combine ftir, as a detector, with a separation technique such as gas chromatography (gc), high performance Hquid chromatography (hplc), or supercritical fluid chromatography (96,97). Instmments such as gc/ftir are often termed hyphenated instmments (98). Pyrolyzer (99) and thermogravimetric analysis (tga) instmmentation can also be combined with ftir for monitoring pyrolysis and oxidation processes (100) (see Analytical methods, hyphenated instruments). 

Pyrolysis of the parent thiirane oxide 16a monitored by microwave spectroscopy led to the conclusion that the sulfur monoxide is generated in its triplet ground state, although the singlet state ( A) cannot be excluded completely (equation 8). A later study presented evidence, based on the stereoselective addition to dienes of sulfur monoxide generated from thiirane oxide as well as thermochemical data, that the ground state S is formed exclusively ° . ... 

The fluidization and the feeder gas flow were controlled by two Brooks 5850S mass flow controllers. The temperature in both the pyrolysis compartment and in the catalyst compartment was monitored by K-type thermo couples and logged to a computer. 

C Solid State NMR. Earlier workers have used 13 C solid state NMR to monitor char formation during the pyrolysis of cellulose (18). They found the 13C NMR of cellulose heated at progressively higher temperatures shows the loss of aliphatic carbons and the appearance of small broad new resonance peaks at... 

Fig. 6.4 Simple diagram of pyrolysis. 1 Stainless steel tube, 2 electrical heater, 3 temperature control monitor, 4 nitrogen pressure control monitor, 3 product exit valve, 6 condenser, 7 oily products collecting vessel, 8 nitrogen tube...

Thiocarbonyl compounds can be generated thermally in the gas-phase from a variety of precursors. Bock et al. [77JCS(CC)287 82CB492] have shown that pyrolysis of 1,2,4-trithiolane derivatives (81) is especially advantageous for this purpose. The fragmentation reactions were monitored by PE spectroscopy. By this method thioaldehydes including thioformaldehyde and thioketones that polymerize readily were obtained. 1,2,4-Trithiolane 4-oxide (82) yields a mixture of thioformaldehyde and thioformaldehyde oxide. 

The flash pyrolysis of trimethylsilyl azide 705 (1100 K, 0.01 mbar) was monitored by photoelectron spectroscopy, a method already successfully employed in the detection of... 

Sulfenic acid (3) has been synthesized in the gas phase by low-pressure, high-temperature pyrolysis of di-t-butyl sulfoxide (4) and characterized by means of matrix isolation and gas-phase IR spectroscopy (Scheme 4).32 The mechanism of formation of (3) by flash pyrolysis of (4) has been studied by quantum chemical calculations, and different pyrolysis experiments monitored by mass spectrometry. In agreement... 

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