Improved method for producing styrene by ethyl benzene catalyzed dehydrogenation

The improved ethyl benzene catalytically dehydrogenating process of producing styrene features that the water vapor is used to heat the reaction effluent via the heat exchanger in the first stage and divided into two parts, including the main part to mix with ethyl benzene in the entrance of the first dehydrogenation reactor in the vapor/ethyl benzene mass ratio of 0.6-1.4, and the other part to mix with the exited material from the first dehydrogenation reactor in the entrance of the second dehydrogenation reactor, with the total vapor/ethyl benzene mass ratio in the reaction system being 1.2-1.8. Compared with available technology, the present invention has the main advantages of reduced pressure drop and decreased investment for the apparatus.