Application of a Fluidized Bed Reactor in the MTO (Methanol to Olefin) Process: Preparation of Catalyst and Presentation of a Kinetic Model

Abstract

Light olefins are basic raw materials for petrochemical industries and the global demand for the latter is growing. The authors investigated the conversion of methanol to light olefins in presence of acidic SAPO-34 molecular sieve as the reaction catalyst. SAPO-34 was synthesized by hydrothermal method, applying morpholine as the template. The molecular sieve was then changed into protonated form by ion exchange process with ammonium chloride at 80°C. A kinetic study was carried out within the temperature range of 375–425°C and 4 bar pressure using a differential fixed bed reactor. An appropriate kinetic model was presented and the kinetic parameters were evaluated as functions of temperature. In addition, the formation of light olefins was implemented in a fluidized bed reactor under a wide range of operating conditions. The experimental results were correlated with those predicted from a hydrodynamic model. Taguchi's experimental design method was applied to determine the optimum operating parameters of this process conducted in the fluidized bed reactor. The optimized parameters were the following: temperature = 425°C; ratio of inlet gas velocity to minimum fluidizing velocity (U₀/U_mf) = 7; catalyst mean particle size = 240 μm.