porous carbonaceous materials examples are those described in u s pat no 4 978 649 which is hereby incorporated by reference herein in its entirety of note are three dimensional matrix carbonaceous materials which are obtained by introducing gaseous or vaporous carbon containing compounds e g hydrocarbons into a mass of granules of a carbonaceous material e g carbon black decomposing the carbon containing compounds to deposit carbon on the surface of the granules and treating the resulting material with an activator gas comprising steam to provide a porous carbonaceous material a carbon carbon composite material is thus formed the carbon surface area as determined by bet measurement is preferably greater than about 100 m 2 g and more preferably greater than about 300 m 2 g it is known from dissociation equilibria that at 100 u00b0 c phosgene contains about 50 ppm chlorine and that at 200 u00b0 c about 0 4 at 300 u00b0 c about 5 and at 400 u00b0 c about 20 of the phosgene is dissociated into carbon monoxide and chlorine also the higher the reaction temperature the more carbon tetrachloride is generally produced accordingly the temperature of the reaction is generally about 300 u00b0 c or less e g in the range of from 40 u00b0 c to 300 u00b0 c preferably the temperature of the process is from about 50 u00b0 c to 200 u00b0 c more preferably from about 50 u00b0 c to 150 u00b0 c the phosgene produced by the process of this invention typically contains about 300 ppm by weight or less of carbon tetrachloride based upon phosgene i e 300 parts by weight ccl 4 per million parts.