The pyrolysis of neopentane at small extents of reaction

Abstract

The pyrolysis of neopentane, at small extents of reaction, was studied by gas chromatography, in Pyrex reaction vessels between 450' and 530°C and in the initial pressure range 25-200 mm Hg. At initial time, this thermal decomposition can be essentially represented by a homogeneous long-chain radical mechanism. The rate constant of the unimolecular initiation process is approximately given by the expressionThe initial rate constant of the global reaction (order s/z) is nearly equal to This reaction is strongly inhibited by propene or isobutene and self-inhibited by the isobutene formed; an interpretation of all these inhibition phenomena of the neopentane pyrolysis is proposed. Our observations and conclusions, which have been summarized in communications during 1968 and 1969, are compared to those of other authors, particularly to the recent ones of Purnell and colleagues [13] and of Taylor and colleagues [14], [15].

Industrial problems and basic research in pyrolysis and oxidation reactions

“…This first limiting case implies that elementary step 3, hydrogen transfer, is more difficult than elementary step 2. It follows that, in the pyrolysis of pure µ , step 3 is the rate-determining step of chain propagation, [µ•] « [ß•], and chain termination occurs by (ßß). The thermal decomposition of neopentane belongs to this limiting case, in agreement with the various investigations performed on this reaction (3,4,26,33) and the corresponding mechanism: The calculated initial reaction rate also confirms that (3) is the rate-determining step of the propagation:…”

“…Such a mechanism explains, for instance, the inhibition of neopentane pyrolysis by propylene (6) and the inhibition (7) and self-inhibition of the neopentane pyrolysis by isobutene (4). If k3 < k&, Y• is more reactive than ß• when an H atom is abstracted from µ and YH accelerates the pyrolysis of µ .…”

Temperature Gradients in a Continuous Flow Stirred Tank Reactor

“…On the contrary, when the gas is preheated, methane formation clearly is primary (nonzero initial rate). Now, it is well known, from many studies, that methane is a primary product of the reaction (see, e.g., Baronnet et al, 1971).…”

Jet-Stirred Reactor Study of Low-Temperature Neopentane Oxidation: A Combined Theoretical, Chromatographic, Mass Spectrometric, and PEPICO Analysis

“…Numerous studies in the literature have investigated the oxidation chemistry of neopentane in static low-pressure reactors, − rapid compression machines, and shock tubes, − as well as in flow tubes − and in jet-stirred reactors (JSRs). − These techniques allowed the identification of primary and secondary products over a temperature range from 550 to 1718 K. The analysis of these measurements was supported by ab initio calculations and the development of chemical kinetic models. ,, Predictions in particular with the most recent model are generally good, but significant discrepancies on specific species such as 2-methylpropanal suggest that some chain-branching reactions might be missing. KHPs have not been observed until very recently by Eskola et al in time-resolved, Cl-atom-initiated neopentane oxidation experiments.…”