Thermal reactions of acetonitrile at high temperatures. Pyrolysis behind reflected shocks

Abstract

The thermal decomposition of acetonitrile was studied behind reflected shocks in a single pulse shock tube over the temperature range 1350-1950 K at overall densities of approximately 3 x mol/cc. Methane and hydrogen cyanide are the major reaction products. They are formed by an attack of H and CH, radicals on acetonitrile. The initiation step of the pyrolysis is the self dissociation of acetonitrile:(1) CHsCN -CHZCN + H for which the following rate constant was obtained: k 1 = 6.17 x 101'exp(-96.6 x 103/RT)sec-'. Where R is given in units of cal/K mol. Additional reaction products which appear in the pyrolysis are: C,H,, CzH4, CH2-CHCN, CH=CCN, C2HSCN, C2N2, and C 3 , . Acetylene is formed from methane pyrolysis and becomes a major reaction product at high temperatures. Acrilonitrile and cyanoacetylene are secondary products originating from the C&CN radical. Fhte parameters €or the formation of the reaction products are given.

Thermal ignition of acetonitrile. Experimental results and kinetic modeling

“…The thermal decomposition of acetonitrile in a pyrolitic environment was studied in the past [8] but as far as we are aware no computer simulation of the decomposition was ever published. Mackie et al [9] have recently presented an experimental and modeling study of the decomposition of acetonitrile, examining the product distribution in the presence of oxygen.…”

Thermal decomposition of acetonitrile. Kinetic modeling

“…The points on the figures were taken from the study on the thermal decomposition of acetonitrile [6] and are expressed (as they were reported in the original study) as vs. (1/T ϭ 5.5 ϫ 10 K ) composition of acrylonitrile [8] is of the order of which gives a half-life for acrylonitrile decom-…”

“…2 2 among the products of the acetonitrile decomposition study [6] we believe that it must have been there. Succinonitrile is an important stable intermediate which by several decomposition channels contributes to the production of C 2 H 3 CN (reaction 42), and to C 2 H 4 and C 2 N 2 (reaction 43).…”

“…Several years ago a study on the thermal decomposition of acetonitrile (in the absence of oxygen) was performed in this laboratory [6]. The decomposition was studied behind reflected shock waves in a single-pulse shock-tube covering the temperature range at overall densities of ca.…”

Pyrolysis and Combustion of Acetonitrile (CH{sub 3}CN)

“…The pyrolysis of acetonitrile (CH 3 CN) has been studied in a tubular flow reactor from 447 to 760°C in nitrogen (Metcalfe et al 1983), in a stirred-flow reactor from 880 to 960°C in helium (Asmus and Houser 1969), and in a shock tube from 1027 to 1827°C in argon with residence times of 0.7-1.7 ms (Lifshitz, Moran, and Bidani 1987;Ikeda and Mackie 1996). In all the studies, the major products from the pyrolysis of acetonitrile were hydrogen cyanide (HCN) and methane (CH 4 ).…”