System and method for preventing catalyst from overheating

A system for preventing a catalyst from overheating, the system comprising:

• a first reactor filled with a catalyst at least in part and configured to receive reaction gas and produce product gas;
• and
• a second reactor at least partially filled with a catalyst discharged from the first reactor and configured to cool the catalyst discharged from the first reactor,
• wherein the catalyst is circulated between the first reactor and the second reactor by injecting the catalyst cooled in the second reactor into the first rector,
• wherein the second reactor comprises:
• a path of a cooling fluid passing through a catalyst bed in the second reactor;
• and
• a path to allow the reaction gas to pass through the catalyst bed in the second reactor, and
• wherein the reaction gas is pre-heated by heat exchange with the catalyst during passing through the path of the reaction gas and then supplied to the first reactor.