Process for catalytic reaction of gases

A process for the catalytic gaseous phase reaction of a feed gas mixture in a regenerative heat transfer reactor in which heat is recovered from reacted gas by regenerative heat exchange and used to heat feed gas mixture entering the reactor, said reactor having two ends which alternately serve as an inlet for the feed gas mixture and as an outlet for reacted gas, two stationary heat exchange/reaction zones which comprise catalyst, a center zone having an inlet for the feed gas mixture, the center zone connecting the two stationary heat exchange/reaction zones, a first distribution/collection zone between one of the heat exchange/reaction zones and one of the ends of the reactor and a second distribution/collection zone between the other heat exchange/reaction zone and the other end of the reactor, the process comprising

• introducing feed gas mixture into one of said ends of the reactor and passing the feed gas through one of said heat exchange/reaction zones to transfer heat stored in said one heat exchange/reaction zone to the feed gas introduced into the reactor and thereby cool said one heat exchange/reaction zone,
• catalytically reacting the feed gas,
• passing reacted gas through the other of said heat exchange/reaction zones to transfer heat from the reacted gas to said other heat exchange/reaction zone and thereby heat said other heat exchange/reaction zone,
• discharging reacted gas from the other of said ends of the reactor,
• periodically reversing the direction of flow of gas through said reactor in a continuing series of cycles by introducing feed gas mixture into said other end of the reactor so that heat that has been transferred from the reacted gas to said other heat exchange/reaction zone is transferred to the feed gas mixture introduced into the reactor, and
• as an intermediate step in each complete reversal of the direction of flow of gas through the reactor, introducing the feed gas mixture into the center zone, reacting the feed gas in the heat exchange/reaction zone which was being heated immediately prior to the intermediate step, discharging reacted gas from the end of the reactor which served as the reacted gas outlet immediately prior to the intermediate step, purging unreacted feed gas from the distribution/collection zone between the heat exchange/reaction zone which was being cooled and the end of the reactor which served as the feed gas mixture inlet immediately prior to the intermediate step, and combining the purged unreacted feed gas with feed gas mixture being introduced into the reactor.