Hydrocarbon decomposition reactions

Thermochemistry. Profiles of potential energy surfaces which are representative of hydrocarbon decomposition reactions and the associ-... 

In a complementary series of experiments the cobalt/molybdenum disulfide samples were initially treated in hydrogen at S00°C for O.S hours. Under these conditions metal particles which had accumulated at edges were observed to catalyze the removal of material from these regions. When such specimens were subsequently heated in the presence of acetylene there was no evidence for the formation of carbon filaments. It was apparent that when specimens were treated in the hydrocarbon for extended periods at 6S0°C then many of the surface features were obscured by the build up of carbon deposits resulting from uncatalyzcd hydrocarbon decomposition reactions. 

The following reactions will be referred to in this review. The hydrocarbon-decomposition reactions producing H2, CO, CO2, and CH4 may be ... 

The key to the extremely high activity for filament production found with FeO may well reside in the defect structure of this compound. In such a structure the oxygen atoms in the surface will be readily accessible to extraction by protons generated by the hydrocarbon decomposition reaction and as a result the oxide could rapidly attain at the surface an iron rich sponge-like arrangement i.e. the role of FeO is that of a precursor for a high surface area Fe catalyst formed ln-sltu. 

An extension ot this reaction provides a number of other perfluorovinylic halides [54] The type of reaction products from the thermal decomposition reaction and the type of hydrocarbon Grignard reagent used in the exchange reaction are solvent-dependent When an excess ot phenylmagnesium bromide is used, a variety of phenylated products are formed depending on the excess amount used [4S (equation 23)... 

The use of PbEt4 as an anti-knock agent in petrol depends in part on the ability of the ethyl radicals, generated on its thermal decomposition, to combine with radicals produced in the over-rapid combustion of petroleum hydrocarbons chain reactions which are building up to explosion (knocking) are thus terminated short of this. The complete details of how PbEt4 operates are not known, but there is some evidence that minute Pb02 particles derived from it can also act as chain-stoppers . 

Sulfuric acid, Sulfur trioxide Vervalin, H. C., Hydrocarbon Process., 1976, 55(9), 323 Dining sulfonation of 4-nitrotoluene at 32° C with 24% oleum in a 2000 1 vessel, a runaway decomposition reaction set in and ejected the contents as a carbonaceous mass. The thermal decomposition temperature was subsequently estimated as 52°C (but see above). 

NASA conducted studies on the development of the catalysts for methane decomposition process for space life-support systems [94], A special catalytic reactor with a rotating magnetic field to support Co catalyst at 850°C was designed. In the 1970s, a U.S. Army researcher M. Callahan [95] developed a fuel processor to catalytically convert different hydrocarbon fuels to hydrogen, which was used to feed a 1.5 kW FC. He screened a number of metals for the catalytic activity in the methane decomposition reaction including Ni, Co, Fe, Pt, and Cr. Alumina-supported Ni catalyst was selected as the most suitable for the process. The following rate equation for methane decomposition was reported ... 

Silanes have molecular structures analogous to those of saturated hydrocarbons. The decomposition reactions, however, are not similar to those of the... 

The main purpose of this chapter is to survi atmospheric concentrations of photochemical oxidants, with emphasis on surface concentrations and the distribution patterns associated with them. The reason for that em> phasis is that the photochemical oxidants that affect public health and welfare are largely concentrated in this region. The whole subject of stratospheric ozone (and its filtering of ultraviolet light and interactions with supersonic-transport exhaust products), nuclear weapon reaction products, and halogenated hydrocarbon decomposition pr ucts is not treated here. 

In the preceding expression, log(FJ is related to the depression of the fall-off curve at the center relative to the L-H expression in a og k/k ) vs. log(2f/(l -I- X)) plot. The values for F<. can then be related to the properties of specific species and reaction and temperature using methods discussed in Gardiner and Troe (1984). In Fig. 19, values of F for a variety of hydrocarbon decompositions are presented. As evident from this figure, in the limit of zero or infinite temperatures and pressures, all reactions exhibit Lindemann-Hinshelwood behavior and F approaches unity. From this figure, it is clear that L-H analysis generally does an adequate job in... 

The simplest hydrocarbon, methane, has posed a wealth of challenges to experimentalists and theoreticians seeking to discern its combustion mechanism. Methane s reactions have been explored in a wide variety of contexts over the past several decades. We have discussed these briefly the interested reader is referred to the reviews cited in our previous discussion for further details. Due to the scope of this review, we are primarily interested in these reactions insofar as they provide useful benchmarks for the reactions of larger alkylperoxy (RO2 ) and alkoxy (RO ) systems. With respect to the reactive intermediates present in methane combustion and their implications for larger systems, Lightfoot has published a review on the atmospheric role of these species, while Wallington et al. have provided multiple overviews of gas-phase peroxy radical chemistry. Lesclaux has provided multiple reviews of developments in peroxy radical chemistry. Batt published a review of the gas-phase decomposition reactions available to the alkoxy radicals. ... 

This requires sufficient energy inserted into the relevant bond vibration for the bond to break or for bonding locations to move. C-C and C-H bond energies in stable alkanes are greater than 80 kcal/molc, and these processes are very infrequent. As we wiU see later, hydrocarbon decomposition, isomerization, and oxidation reactions occur primarily by chain reactions initiated by bond breaking but are propagated by much faster abstraction reactions of molecules with parent molecules. 

In the decomposition reactions of acetylene major interest must be in the problem of carbon formation. This problem has been the subject of a number of recent reviews (2, 56, 58, 59, 62, 66). Porter (58, 59) advocated the viewpoint that acetylene is the precursor of carbon in any hydrocarbon system. This is a somewhat controversial point which is not specific to the present discussion. There is no question that when acetylene is formed, decomposition to carbon is one reaction by which it will disappear. 

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