Home – Home – Jornals – Chemistry for Sustainable Development 2004 number 6

The kinetics of ethyl radical generation during the pyrolysis of n-undecane on barium chloride (accelerating the heterogeneous constituent of the process) and on defect-bearing magnesium oxides (accelerating the homogeneous constituent of the process) was investigated by means of freezing out in the cavity of the EPR spectrometer. It was shown that the activation energy of radical generation on barium chloride (E = 192 kJ/mol) is lower than the activation energy of thermal pyrolysis (E = 322 kJ/mol). The phenomenon of ignition of the surface is observed with the catalysts that accelerate the homogeneous constituent of the process and create the «catalysis sphere.» Below the critical temperature, in spite of the presence of catalysts, ordinary thermal pyrolysis goes on between the catalyst granules. At a higher temperature, the catalyst generates radicals with the activation energy characteristic of the radical reactions (E = 4 kJ/mol). The possibility to increase the productivity and to control the selectivity of pyrolysis of hydrocarbons by including non-conventional heterogeneous catalysts into the process is demonstrated.