Kinetics of pyrolysis of furan

Abstract

The kinetics of pyrolysis of furan vapour diluted in argon have been studied behind reflected shock waves in a shock tube both by time-resolved infrared CO₂ laser absorption spectrometry and by single pulse shock techniques of product analysis over the temperature range 1100–1700 K, at pressures of ca. 20 atm and at uniform residence times of ca. 300 µs. The rate of overall disappearance of furan, as measured by absorption spectrometry, was found to be first order in furan concentration, with a rate constant of k_overall= 10^15.3±0.3 exp[–326(±8) kJ mol^–1/RT] s^–1 in agreement with a previous determination by Lifshitz et al.(A. Lifshitz, M. Bidani and S. Bidani, J. Phys. Chem., 1986, 90, 5373). Principal products were carbon monoxide, C₃H₄(propyne and allene) and acetylene. Ketene was identified in the products by FTIR spectroscopy.

A detailed chemical reaction model for the pyrolysis was developed and shown to give good predictions of the concentration profiles of furan and the major products. Modelling and thermochemical considerations led to the postulate that the initiation of pyrolysis takes place by C—O bond scission to a biradical which can undergo decomposition, via parallel reaction paths, to the observed products.