Conversion of Petroleum Pyrolysis

Note how we used single-barbed (fishhook) arrows in these examples to show the formation of a new covalent bond by the combination of two electrons. In the hydrogen abstraction reactions, electrons from a bond being broken combine with unshared electrons to form new bonds. 

Control of such processes frequently requires the use of special catalysts, such as crystalline sodium aluntinosilicates, also called zeolites. For example, zeolite-catalyzed pyrolysis of dodec-ane yields a mixture in which hydrocarbons containing from three to six carbons predominate. 

What is the function of the zeolite catalyst It speeds up the pyrolysis, so that the process occurs at a lower temperature than otherwise would be the case. The catalyst also causes certain products to form preferentially. Such enhanced reaction selectivity is a feature frequently observed in catalyzed reactions. How does this happen  

Many organic reactions occur at a useful rate only because of the presence of a catalyst The catalyst may be an acid (a proton), a base (hydroxide), a metal surface or metal compound, or a complex organic molecule. In nature, enzymes usually fulfill this function. The degree of reaction acceleration induced by a catalyst can amount to many orders of magnitude. Enzyme-catalyzed reactions are known to take place 10 times faster than the uncatalyzed processes. The use of catalysts allows many transformations to take place at lower temperatures and under much milder reaction conditions than would otherwise be possible. 

Breaking an alkane down into smaller fragments is also known as cracking. Snch processes are important in the oil-refining industry for the production of gasoline and other Uquid fuels from petroleum. 

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In connection with thermal and catalytic processes such as coking, pyrolysis and catalytic cracking for the conversion of petroleum fractions, there is considerable interest in the mechanism of the transformation of various... 

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. 

Several cases of spontaneous ignition after exposure to air of fine coke particles removed from filter strainers on a petroleum refinery furfural extraction unit have been noted. This has been associated with the use of sodium hydrogen carbonate (bicarbonate) injected into the plant for pH control, which produced a pH of 10.5 locally. This would tend to resinify the aldehyde, but there is also the possibility of a Cannizzaro reaction causing conversion of the aldehyde to furfuryl alcohol and furoic acid. The latter, together with other acidic products of autoxidation of the aldehyde, would tend to resinily the furfuryl alcohol. Pyrolysis GLC showed the presence of a significant proportion of furfuryl alcohol-derived resins in the coke. The latter is now discarded into drums of water, immediately after discharge from the strainers, to prevent further incidents. 

Chemical conversion of vegetable oils to general purpose liquid fuels ( biofuels, and biodiesel ) has also been successfully explored [34, 35]. However, the small size of this resource makes it unlikely that this could do more than supplement petroleum-based sources. Probably the more significant developments to extend petroleum-based liquid fuels lie in the recovery of oil from the tar sands, and the pilot plant projects involving oil shale pyrolysis experiments to liquid fuels. 

As the book name implies, we attempted to bring together specialists to present the state of the science in the complete fuel cycle, from feedstock to upgraded liquid fuels suitable as replacements for petroleum-derived fuels. The introductoiy chapter contains a discussion of biomass pyrolysis and its place in a renewable fuel economy. Contributions to this book were received from five countries, a fact indicating the widespread interest in this conversion option for biomass, and permitting the enhancement and establishment of collaborative efforts. 

Schenk H. J., Di Primio R. and Horsfield B. (1997) The conversion of oil into gas in petroleum reservoirs. Part 1 comparative kinetic investigation of gas generation from crude oils of lacustrine, marine and fluviodeltaic origin by programmed-temperature closed-system pyrolysis. Org. Geochem. 26, 467-481. 

The current world production of ethene and propene is mainly covered by the petrochemical route based on steam cracking, that is, thermal pyrolysis of petroleum liquids (naphtha, gas oils) and natural gas condensates, that is, ethane, propane, etc. [13-15]. A schematic stoichiometry is given in Eq. (5.2). As an alternative, ethanol can be converted via catalytic dehydration to ethene, as shown in Eq. (5.3) [16]. For steam cracking of naphtha, the reaction stoichiometry gives a maximum product yield of nearly 100 wt%, whereas ethanol conversion can lead only to maximum yields of 61 wt%. 

A narrow view of this mission would include only the use of analytical pyrolysis techniques (e.g., pyrolysis-mass spectrometry (Py-MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS)) to identify and measure contaminants in samples of outdoor air, soils, sediments, water, and biota. In order to include interesting and useful applications of analytical pyrolysis techniques that otherwise might not be mentioned in the other chapters of this handbook, a broader view of environmental applications will be used to include such topics as the use of analytical pyrolysis to gain an understanding of natural enviromnental processes, such as the conversion of plant materials into soil, coal, and petroleum hydrocarbons. This subject was included in a recent review paper describing the use of analytical pyrolysis for environmental research. Several other review papers contain references pertinent to environmental analysis. ... 

The reaction kinetic constants activation energy E and frequency factor A, can only be correlated with the concentration of paraffinic carbon, CP (from structural group analysis) with the concentration of dispersion medium (fiom colloid analysis) and with the H/C ratio (from elemental analysis). These functions show correlation coefficients of an acceptable magnitude. Examination of the correlation of the concentration of maltenes revealed a similar tendency but with very low coefficients of correlation. It is well known that the dispersion medium contains the highest concentration of chemical bonds, which can be cracked under the chosen reaction conditions [4-20]. In the pyrolysis experiments from distillation residues, about 92 % of the dispersion medium was converted, whereas conversion of the petroleum resins was only 83 %, despite the fact that the kinetic coefficients are of nearly the same magnitude for the two components. 

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