Isothermal reactor

The utility model relates to an isothermal reactor and aims at solving the problems that the current isothermal reactor system is unstably controlled and the catalyst is easily deactivated. According to the technical scheme, the isothermal reactor comprises a shell body, wherein an upper chamber water distributor and a lower chamber water distributor are respectively arranged at the upper section and the lower section in the shell body; the upper chamber water distributor is connected with the lower chamber water distributor by virtue of a plurality of uniformly distributed heat exchange pipes; the upper chamber water distributor is communicated with a water vapor outlet in the top of the shell body; the lower chamber water distributor is connected with a furnace water supply pipe at the bottom of the shell body; a raw material gas inlet is formed in the top of the shell body; a reaction gas outlet pipe is arranged at the bottom of the shell body; the middle section of the shell body is filled with a catalyst