Process and reactor for producing phosgene

A process for producing phosgene by gas-phase reaction of carbon monoxide and chlorine in the presence of a catalyst in a reactor which comprises a plurality of parallel catalyst tubes which are filled with the catalyst and around which at least one fluid heat transfer medium flows, where a feed stream of a mixture of a chlorine input stream and a carbon monoxide input stream is fed into the catalyst tubes and is allowed to react to give a phosgene-comprising product gas mixture, wherein the reaction is carried out at an area load of from 3.7 to 9 kg of phosgene/m2s, and wherein an amount of carbon tetrachloride formed from a reaction of activated carbon with chlorine is less than 125 g per metric ton of phosgene produced.