Hydrocarbon pyrolysis products

There is a dramatic increase in gas yield with increasing temperature of pyrolysis. While the hydrocarbon pyrolysis product yield increases with pyrolysis temperature, the yield of the oil fraction is higher at the lower pyrolysis temperatures. The composition of the pyrolysis oil also changes with pyrolysis temperature, generally containing larger... 

Table III. Gases and Light Hydrocarbon Pyrolysis Products ...

Table 4.1 Hydrocarbon pyrolysis products from polyvinyl chloride (7.80 °C/s) ...

From the time that isoprene was isolated from the pyrolysis products of natural mbber (1), scientific researchers have been attempting to reverse the process. In 1879, Bouchardat prepared a synthetic mbbery product by treating isoprene with hydrochloric acid (2). It was not until 1954—1955 that methods were found to prepare a high i i -polyisoprene which dupHcates the stmcture of natural mbber. In one method (3,4) a Ziegler-type catalyst of tri alkyl aluminum and titanium tetrachloride was used to polymerize isoprene in an air-free, moisture-free hydrocarbon solvent to an all i7j -l,4-polyisoprene. A polyisoprene with 90% 1,4-units was synthesized with lithium catalysts as early as 1949 (5). 

Dente and Ranzi (in Albright et al., eds.. Pyrolysis Theory and Industrial Practice, Academic Press, 1983, pp. 133-175) Mathematical modehng of hydrocarbon pyrolysis reactions Shah and Sharma (in Carberry and Varma, eds.. Chemical Reaction and Reaction Engineering Handbook, Dekker, 1987, pp. 713-721) Hydroxylamine phosphate manufacture in a slurry reactor Some aspects of a kinetic model of methanol synthesis are described in the first example, which is followed by a second example that describes coping with the multiphcity of reactants and reactions of some petroleum conversion processes. Then two somewhat simph-fied industrial examples are worked out in detail mild thermal cracking and production of styrene. Even these calculations are impractical without a computer. The basic data and mathematics and some of the results are presented. 

Plot the selectivity to C4H8 as a function of ethane conversion. Does it behave like a secondary or primary product Consult the paper by Dean (1990), and describe additional reactions which lead to molecular weight growth in hydrocarbon pyrolysis systems. While some higher molecular weight products are valuable, the heavier... 

The Curie Point flash evaporation-pyrolysis gas chromatography-mass spectrometric method [32] described in section 2.2.1.2 for the analysis of aliphatic hydrocarbons in soil has also been applied to the determination of polystyrenes in soil via identification and determination of their unzipping pyrolysis products, such as styrene monomer, a-methyl styrene, 3-methyl styrene, 4-methyl styrene, a-3 dimethyl styrene, 3-ethylstyrene, a-4 dimethyl styrene, 3.5 dimethyl-styrene, a-2 or 2,5 or 2.4 dimethyl styrene also various phenyl ethers. 

The flash evaporation pyrolysis gas chromatography method [16] as described in section 11.1.4 for the determination of polycyclic aromatic hydrocarbons, haloorganics, aliphatic hydrocarbons, heteroaromatics, elemental sulphur and pyrolysis products of synthetic polymers in soils has also been applied to non-saline sediments. 

Mansuy et al. [97] investigated the use of GC-C-IRMS as a complimentary correlation technique to GC and GC-MS, particularly for spilled crude oils and hydrocarbon samples that have undergone extensive weathering. In their study, a variety of oils and refined hydrocarbon products, weathered both artificially and naturally, were analyzed by GC, GC-MS, and GC-C-IRMS. The authors reported that in case of samples which have lost their more volatile n-alkanes as a result of weathering, the isotopic compositions of the individual compounds were not found to be extensively affected. Hence, GC-C-IRMS was shown to be useful for correlation of refined products dominated by n-alkanes in the C10-C20 region and containing none of the biomarkers more commonly used for source correlation purposes. For extensively weathered crude oils which have lost all of their n-alkanes,it has been demonstrated that isolation and pyrolysis of the asphaltenes followed by GC-C-IRMS of the individual pyrolysis products can be used for correlation purposes with their unaltered counterparts [97]. 

For the first time we have discovered transparent (painted in various colours) thread-like crystals of carbon among the products of hydrocarbon pyrolysis and during synthesis of silicon and boron carbides (Fig. 3.6) [12]. The X-ray spectral analysis has shown that the transparent threads consist of carbon (Fig. 3.7). 

Environmental chemicals and pollutants are also capable of inducing P450 enzymes. As previously noted, exposure to benzo[a]pyrene and other polycyclic aromatic hydrocarbons, which are present in tobacco smoke, charcoal-broiled meat, and other organic pyrolysis products, is known to induce CYP1A enzymes and to alter the rates of drug metabolism. Other environmental chemicals known to induce specific P450s include the polychlorinated biphenyls (PCBs), which were once used widely in industry as insulating materials and plasticizers, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin, TCDD), a trace byproduct of the chemical synthesis of the defoliant 2,4,5-T (see Chapter 56). 

Several compounds were also found to have a seasonal distribution. Kubatova et al. (2002) found that concentrations of lignin and cellulose pyrolysis products from wood burning were higher in aerosol samples collected during low-temperature conditions. On the other hand, concentrations of dicarboxylic acids and related products that are believed to be the oxidation products of hydrocarbons and fatty acids were highest in summer aerosols. PAHs, which are susceptible to atmospheric oxidation, were also more prevalent in winter than in summer. These results suggest that atmospheric oxidation of VOCs into secondary OAs and related oxidative degradation products are key factors in any OA mass closure, source identification, and source apportionment study. However, additional work is much desirable to assess the extent and seasonal variation of these processes. 

There was a much larger variation between pyrolysis products volatile fractions for the exinites and vitrinites. The sporinite yielded mostly normal alkanes and alkenes up to approximately C19 with C16 being the most abundant product. The very low molecular weight hydrocarbons such as methane and ethane were not analyzed. Also, benzene and phenol derivatives were found as minor products. The vitrinite products were dominated by aromatics such as alkyl benzenes, alkylnaphthalenes, phenols, and naphthols. The smaller alkane/alkenes were also found. These results are most consistent with what was found in pyrolysis MS of sporinites and vitrinites (5,7). 

FIGURE 15.14 FTIR monitored online during aTG-FTIR experiment (this means several hundreds of FTIR spectra are taken) of PA 66-GF/MPP enables the identification of volatile pyrolysis products (H20, NH3, C02, cyclopentanone, amines, and hydrocarbons) at distinct stages of the decomposition and the investigation of the product release rates. 

Ross, L. L., Shu, W. R., Computer Modeling of Hydrocarbon Pyrolysis for Olefins Production, in "Thermal Hydrocarbon Chemistry", Adv. Chem. Series,... 

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