Hydrocarbon chemistry conversion

CHARLES A. MIMS is a Professor of Chemical Engineering and Applied Chemistry at the University of Toronto. He earned his B.Sc. in chemistry at the university of Texas, Austin, and his Ph.D. in physical chemistry at the University of California, Berkeley. He has 15 years of industrial research experience at Exxon, is the author of over 65 research publications, and holds three patents. His research interests focus on catalytic kinetics in various energy and hydrocarbon resource conversion reactions, and the fundamentals of surface reactions. 

Another chemical approach to the chemical conversion of methane involves organometallic reactions.85-89 Interesting work with iridium complexes and other transition metal insertion reactions (rhodium, osmium, rhenium, etc.) were carried out. Even iron organometallics were studied. These reactions take place in the coordination spheres of the metal complexes, but so far the reactions are stoichiometric and noncatalytic.77 In terms of synthetic hydrocarbon chemistry, these conversions are thus not yet practical, but eventually it is expected that catalytic reactions will be achieved. 

Base-catalyzed hydrocarbon conversions, although generally less common than acid-catalyzed reactions, also play a significant role in hydrocarbon chemistry. They proceed through proton abstraction giving intermediate carbanions 92A 94... 

Methanol Synthesis. The transformation of synthesis gas to methanol [Eq. (3.3)] is a process of major industrial importance. From the point of view of hydrocarbon chemistry, the significance of the process is the subsequent conversion of methanol to hydrocarbons (thus allowing Fischer-Tropsch chemistry to become more selective). 

The objective of this book is to serve as a practical reference work on testing for the main hydrocarbon-conversion processes applied in oil refineries catalytic cracking, hydroprocessing, and reforming. These fields were combined because of the clear analogies and congruence between the areas, such as deactivation of active sites by coke, mass-transfer phenomena of hydrocarbons into solid catalysts, hydrocarbon chemistry and reaction kinetics, and downscaling of commercial conditions to realistic small-scale tests. 

This work was supported by NSF Grant AER75-17453 A Study of the Use of Microwave Heating for the Release of Oil from Oil Shale. Portions of this paper were presented at the Annual Oil Shale Conversion Symposium, September 1977, University of Wyoming, Laramie, Wyoming and at the Symposium on Thermal Hydrocarbon Chemistry presented before the Division of Petroleum Chemistry, American Chemical Society. 

The formation of the first C-C bond is the kinetically limited step of MeOH transformation. As soon as the first C-C bond has been formed, the subsequent conversion of light olefins to paraffins, aromatics, naphthenes, and higher olefins proceeds via classical carbenium ion mechanisms with concurrent hydrogen transfer taking place [54]. This chemistry is well known from hydrocarbon chemistry in the presence of acid sites [54]. Hutchings also suggested that the aromatics are most likely formed from primary olefins [22]. 

TaF has been characterized by ir, Raman, x-ray diffraction, and mass spectrometry (3,11,12). TaF has been used as a superacid catalyst for the conversion of CH to gasoline-range hydrocarbons (qv) (12) in the manufacture of fluoride glass and fluoride glass optical fiber preforms (13), and incorporated in semiconductor devices (14). TaF is also a catalyst for the Hquid-phase addition of HF to polychlorinated ethenes (15). The chemistry of TaF has been reviewed (1,16—19). Total commercial production for TaF is thought to be no more than a few hundred kilograms aimuaHy. 

H. Pines, The Chemistry of Catalysis Hydrocarbon Conversions, Academic Press, Inc., New York, 1981, pp. 173—174. 

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 ... 

Another current development in the use of F-T chemistry in a three-phase slurry reactor is Exxon s Advanced Gas Conversion or AGC-21 technology (Eidt et al., 1994 Everett et al., 1995). The slurry reactor is the second stage of a three-step process to convert natural gas into a highly paraffinic water-clear hydrocarbon liquid. The AGC-21 technology, as in the Sasol process, is being developed to utilize the large reserves of natural gas that are too remote for economical transportation via pipelines. The converted liquid from the three-step process, which is free of sulfur, nitrogen, nickel, vanadium, asphaltenes, polycyclic aromatics, and salt, can be shipped in conventional oil tankers and utilized by most refineries or petrochemical facilities. 

We are not aware of any industrial application that uses metal activation of C-H bonds to obtain functionalised molecules. We have included this topic, because it is potentially of great importance by providing a short-cut for the conversion of hydrocarbons to its functionalised derivatives. Two extreme cases will be discussed, reactions with electron-rich metal complexes and reactions with electrophilic metal complexes. As always in organometallic chemistry there are cases in between that utilise both bonding interactions. 

The bis-hydroxylamine adduct [Fe (tpp)(NH20H)2] is stable at low temperatures, but decomposes to [Fe(tpp)(NO)] at room temperature. [Fe(porphyrin)(NO)] complexes can undergo one-and two-electron reduction the nature of the one-electron reduction product has been established by visible and resonance Raman spectroscopy. Reduction of [Fe(porphyrin)(NO)] complexes in the presence of phenols provides model systems for nitrite reductase conversion of coordinated nitrosyl to ammonia (assimilatory nitrite reduction), while further relevant information is available from the chemistry of [Fe (porphyrin)(N03)]. Iron porphyrin complexes with up to eight nitro substituents have been prepared and shown to catalyze oxidation of hydrocarbons by hydrogen peroxide and the hydroxylation of alkoxybenzenes. ... 

These reactions represent a gentle method for conversion of aldehydes to hydrocarbons in yields of 40-95% and are frequently used, especially in saccharide chemistry [795, 797, 798. ... 

The chemistry of a third group of conversion techniques -i.e., partial conversion methods which skim hydrocarbon gases and/or liquids from the coal and leave a char suitable for use as a boiler fuel or gasification feedstock - is. If anything, even more speculative than the chemistry of liquefaction. 

This paper touches on the chemistry of coal gasification and liquefaction comments on the current status of conversion processes and the influence of coal properties on coal performance in such processes and examines the contributions which coal conversion could make towards attainment of Canadian energy self-sufficiency. Particular attention is directed to a possible role for the medium-btu gas in long-term supply of fuel gas to residential and industrial consumers to linkages between partial conversion and thermal generation of electric energy and to coproduction of certain petrochemicals, fuel gas and liquid hydrocarbons by carbon monoxide hydrogenation. 

Pines, H., The Chemistry of Catalytic Hydrocarbon Conversions. p. 139 Academic Press, New York, 1981. 

The model includes fundamental hydrocarbon conversion kinetics developed on fresh catalysts (referred to as start-of-cycle kinetics) and also the fundamental relationships that modify the fresh-catalyst kinetics to account for the complex effects of catalyst aging (deactivation kinetics). The successful development of this model was accomplished by reducing the problem complexity. The key was to properly define lumped chemical species and a minimum number of chemical reaction pathways between these lumps. A thorough understanding of the chemistry, thermodynamics, and catalyst... 

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