System and method for preventing catalyst from overheating

1. A method for preventing a catalyst from overheating, the method comprising:

producing product gas by supplying reaction gas to a first reactor filled with a catalyst at least in part;

discharging some of the catalyst from the first reactor and supplying the catalyst to a second reactor that is at least partially filled with catalyst discharged from the first reactor;

cooling the catalyst in the second reactor by allowing a cooling fluid to pass through a catalyst bed in the second reactor; and

supplying the catalyst cooled in the second reactor to the first reactor,

wherein the second reactor comprises 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.

2. The method of claim 1 , wherein the producing the product gas comprises cooling the catalyst in the first reactor by allowing another cooling fluid to pass through the first reactor.

3. The system of claim 1 , wherein the catalyst is a catalyst of a particle shape having a diameter ranging from 1 to 9,000 micrometers, and

wherein the producing the product gas further comprises injecting the reaction gas into the first reactor at a speed higher than a minimum fluidization velocity of the catalyst.

4. The method of claim 1 , wherein the first reactor is a fluidized bed reactor and the product gas is produced in a state in which the catalyst in the first reactor is fluidized.