Method for producing propylene from a flow containing C4 to C8 olefins

In propylene production by vaporizing a liquid feed stream containing 4-8 carbon (C) olefins, superheating, mixing with superheated steam, catalytic reaction at 450-500 degrees Celsius and 0.5-3.0 bar, cooling and partial condensation, the remaining gas phase is compressed to 20-30 bar and separated into a gas phase, and a liquid phase, which is then separated further separated. Production of propylene from a liquid feed stream containing 4-8 carbon (C) olefins involves vaporization at 25-200 degrees Celsius and superheating to 350-400 degrees Celsius, mixing the resultant vapor containing olefins with superheated steam, reacting this mixture on a shape-selective pentasil-type zeolite stationary bed catalyst (9) at an inlet temperature of 450-500 degrees Celsius and pressure of 0.5-3.0 bar (absolute), cooling the reaction mixture to 100-200 degrees Celsius and partial condensation by cooling to 40 to under 100 degrees Celsius to form a gas phase (I), mainly ethylene, propylene, 4-8 C olefins and other hydrocarbons, and a liquid phase, mainly water, which is recycled to the feed stream. The novel features are that (I) formed by partial condensation in a quench stage (13) is compressed to 20-30 bar (absolute), the phases leaving the compression stage (15) are separated into a gas phase, mainly ethylene, propylene and other light hydrocarbons, and a liquid phase (II) containing C4+ olefins and (II) is separated into a fraction containing 4-6 C olefins and a fraction containing C7+ olefins.