High temperature reactions of chloroform with methane

The reactions of Chloroform with Methane were studied at atmospheric pressure in the temperature range of 550-800 deg C, and using three different reactor diameters. The reaction was found to follow pseudo-first order kinetics in the presence of excess Methane and Argon, and the kinetic parameters were determined for each of the reactor sizes. The resulting global Arrhenius expressions are: For 0.4 cm ID Kexp = 2.03 * 108 exp (-34000/RT) For 1.05 cm ID Kexp = 9.86 * 108 exp (-37950/RT) For 1.6 cm ID Kexp = 4.17 * 108 exp (-36760/RT) An increase in the surface to volume ratio of the reactor tube was found to accelerate the decomposition rate of Chloroform, but it did not effect the stable product distribution. After decoupling the homogeneous gas phase rate constant and the wall rate constant, the first order reaction rate expressions were obtained as follows: For gas phase : Kb = 6 * 1010 expp(-46700/RT) For the wall : Kw = 8.8 * 106 exp(-33000/RT) The major stable reaction products, identified by Mass/Spec. analysis, were C2 H2 , CH3 Cl , C2 H3 Cl, C2 H2 Cl2 , C2 HCl3 C2 Cl4 , C2 HCl5 , C2 Cl6 and traces of CCl4 , C2 H2 Cl4 , C3 H2 Cl4 , C4 HCl5 and C4 Cl6 . The residence times used ranged from 0.5 sec to 3.2 sec. Complete destruction of all the chlorinated compounds occured at 800 deg C and residence time less than 0.5 sec. A reaction mechanism was established, including all the elementary steps needed to lead to the observed product distribution. It was proven that the initial reaction step is unimolecular decomposition of chloroform, taking place by an HCi molecule elimination and carbene formation,as the following scheme describes : CHCl3 ---\u3e :CCl2 + HC