Hydrocarbon fundamental processes

One particularly important case of distillation sequencing is worthy of special consideration. This is the case of crude oil distillation, which is the fundamental process underlying the petroleum and petrochemicals industry. Crude oil is an extremely complex mixture of hydrocarbons... 

The fundamental step in acid-catalyzed hydrocarbon conversion processes is the formation of the intermediate carbocations. Whereas all studies involving isomerization, cracking, and alkylation reactions under acidic conditions (Scheme 5.1) agree that a trivalent carbocation (carbenium ion) is the key intermediate, the mode of their formation of this reactive species from the neutral hydrocarbon remained controversial for many years. 

The thermodynamic equilibria of surfactant molecules in hydrocarbon solutions involve four fundamental processes dissolution, micellization, solubilization and interfacial processes, see Fig. 3.3 (Kertes and Gutman, 1976 Kon-no, 1993 Moroi, 1992). 

Fig. 3.3. Four fundamental processes for thermodynamic equilibria of surfactant molecules in hydrocarbons (1) dissolution of molecules into solution, (2) micellization (or aggregation) of dissolved molecules, (3) adsorption (solubilization) of molecules at an interface, and (4) interfacial processes of surfactant molecules (oVW = surfactant molecule), (Moroi, 1992)...

The d group 3 and lanthanide complexes Cp MR are isoelectronic with the [Cp2MR]+ catalysts discussed in the previous section. These nonionic complexes are soluble in most hydrocarbons and as one-component systems make ideal models for many of the fundamental processes in polymerization catalysis. For example, an alkyl-alkene complex can be observed by NMR when Cp 2 YH is allowed to react with an o , )-diene (equation 13). ... 

The fundamental advantage of the use of fluidized catalysts for the highly exothermic hydrocarbon synthesis consists of a radical solution of the crucial heat transfer problem, which limited the yield per space and time in the case of fixed catalyst beds. The fluidized system presents the possibility of going to higher synthesis temperatures which means higher conversions with cheaper catalysts and more efficient heat recovery. This can be done without producing excessive amounts of carbon or methane. The yields of valuable olefinic hydrocarbons are very high in comparison with other hydrocarbon synthesis processes. 

Traditional hydrocarbon conversion process models have implemented lumped kinetics schemes, where the molecules are aggregated into lumps defined by global properties, such as boiling point or solubility. Molecular information is obscured due to the multi-component nature of each lump. However, increasing environmental concerns and the desire for better control and manipulation of the process chemistry have focused attention on the molecular composition of both the feedstocks and their refined products. Modeling approaches that account for the molecular fundamentals underlying reaction of complex feeds and the subsequent prediction of molecular properties require an unprecedented level of molecular detail. 

The fundamental processes of charge carrier generation and motion in hydrocarbon liquids reviewed above appear to be sufficient to explain the onset of electrical breakdown under a variety of conditions. 

The first demonstration of catalytic conversion of synthesis gas to hydrocarbons was accompHshed ia 1902 usiag a nickel catalyst (42). The fundamental research and process development on the catalytic reduction of carbon monoxide was carried out by Fischer, Tropsch, and Pichler (43). Whereas the chemistry of the Fischer-Tropsch synthesis is complex, generalized stoichiometric relationships are often used to represent the fundamental aspects ... 

Whereas catabolism is fundamentally an oxidative process, anabolism is, by its contrasting nature, reductive. The biosynthesis of the complex constituents of the cell begins at the level of intermediates derived from the degradative pathways of catabolism or, less commonly, biosynthesis begins with oxidized substances available in the inanimate environment, such as carbon dioxide. When the hydrocarbon chains of fatty acids are assembled from acetyl-CoA units, activated hydrogens are needed to reduce the carbonyl (C=0) carbon of acetyl-CoA into a —CHg— at every other position along the chain. When glucose is... 

The addition of metal hydrides to C—C or C—O multiple bonds is a fundamental step in the transition metal catalyzed reactions of many substrates. Both kinetic and thermodynamic effects are important in the success of these reactions, and the rhodium porphyrin chemistry has been important in understanding the thermochemical aspects of these processes, particularly in terms of bond energies. For example, for first-row elements. M—C bond energies arc typically in the range of 2, i-. i() kcal mol. M—H bond energies are usually 25-30 kcal mol. stronger, and as a result, addition of M—CH bonds to CO or simple hydrocarbons is thermodynamically unfavorable. 

John A. Davenport, Prevent Vapor Cloud Explosions, Hydrocarbon Processing (March 1977), pp. 205-214 and Orville M. Slye, Loss Prevention Fundamentals for Process Industry, Paper presented at AICHE Loss Prevention Symposium, New Orleans, LA, March 6-10,1988. 

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