Thermal decomposition of 1,2 butadiene

Abstract

The thermal decomposition of 1,2 butadiene has been studied behind reflected shock waves over the temperature and total pressure ranges of 1300-2000 K and 0.20-0.55 atm using mixtures of 3% and 4.3% 1,2 butadiene in Ne. The major products of the pyrolysis are C2H,, C4Hz, C2H4, CH, and CsH6. Toluene was observed as a minor product in a narrow temperature range of 1500-1700 K. In order to model successfully the product profiles which were obtained by time-of-flight mass spectrometry, it was necessary to include the isomerization reaction of 1,2 to 1,3 butadiene. A reaction mechanism consisting of 74 reaction steps and 28 species was formulated to model the time and temperature dependence of major products obtained during the course of decomposition. The importance of C3H3 in the formation of benzene is demonstrated.C3H3 similar to that in the allene pyrolysis experiments. The C -CH3 bond in 1,2 butadiene is the weakest bond [41. Almost equal amounts of benzene were detected over comparable temperature ranges. However, the respective benzene profiles displayed different shapes. The purpose of this study is to understand the differences in the rates of benzene formation from 1,2 butadiene and allene pyrolyses and to provide additional evidence for the role of C3H3. A previous study of Collin and Lossing [51 concentrated on the ionization and dissociation of 1,2 butadiene and the subsequent determination of the C3H3 heat of formation. The emphasis herein is on the identity of the reaction products, their temporal behavior, and the mechanism attendent to the thermal decomposition.

The UMIST database for astrochemistry 2012

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Fast, scalable master equation solution algorithms. III. Direct time propagation accelerated by a diffusion approximation preconditioned iterative solver

“…36,37 The formation of propargyl is believed to be a significant step in the formation of simple aromatic hydrocarbons and thus polycyclic aromatic hydrocarbons and soot. [36][37][38][39][40][41][42][43] The major route to propargyl proposed by Miller and Melius 36 involves the insertion of singlet methylene into acetylene to form C 3 H 4 , which isomerizes before decomposing to propargyl. The rate constant for the reaction of singlet methylene with acetylene to form C 3 H 4 and eventually propargyl has been measured experimentally by several different methods over the past 20 years.…”

Detailed kinetic modeling of 1,3-butadiene oxidation at high temperatures

“…The second pathway, originally proposed [22,24] to occur as a concerted unimolecular process, was lately considered [25] to proceed in two steps via the formation of vinylidene. Studies on 1,2-butadiene [28,29] and 2-butyne [31] demonstrated relatively low-energy barriers for their mutual isomerization, and particularly for their isomerization to 1,3-butadiene. Based on these results Hidaka et al [21] proposed a reaction mechanism that was shown to reconcile a large amount of experimental data for 1,3-butadiene [22 -27] and its isomers [28 -31].…”

“…Significant progress was made in the pyrolysis kinetics. Hidaka et al [21] reviewed studies on the pyrolysis of 1,3-butadiene [22 -27], 1,2-butadiene [28,29], 1-butyne [30], and 2-butyne [31]. A kinetic model was proposed [21] which was capable of reconciling a wide spectrum of experimental data.…”