Phosgene Formation Via Carbon Monoxide and Dichlorine Reaction over an Activated Carbon Catalyst: Towards a Reaction Model

The reaction of carbon monoxide and dichlorine over an activated carbon catalyst to produce phosgene is examined using a previously described micro-reactor arrangement. An activation energy of 34.1 kJ mol−1 is determined. The reaction profile at 323 K as a function of time-on-stream establishes steady-state operation to be achieved rapidly, with no deactivation evident within a reaction time of 300 min.. Phosgene production seemingly exhibits 100 % selectivity. However, mass balance measurements indicate a small degree of carbon and chlorine retention by the catalyst that is not directly coupled to the formation of gaseous phosgene. The molecular form of the retained moieties is unknown but, nonetheless, their presence reduces the atom economy of the process and, correspondingly, attenuates total phosgene selectivity. The order of reaction with respect CO, Cl2 and COCl2 is, respectively, 1, 0.5 and 0; leading to the determination of the rate law for phosgene production over this catalyst.