A Study On The Kinetic Model Of Methanol To Olefins Reaction Process

With highly increasing demand for ethene, propene and shortage of oil resources, methanol to olefins (MTO) process which is considered as a new technology to produce light olefins by non-oil resources has been enjoyed great popularity in many countries. Study of MTO kinetics is an important basis of the following reactor design, and also has a practical guiding significance for the MTO process optimization.Firstly based on MTO reaction feature, thermodynamics for MTO process has been calculated and analyzed. It has been concluded that MTO reactions are strongly exothermic and reaction rates are not restricted by thermodynamics. Then on the basis of MTO mechanism, lumped kinetic model has been built considering both catalyst deactivation caused by coke and water in the feed which not only inhibits reaction in MTO process but also alleviates catalyst deactivation rate. Parameters of the model has been estimated by experimental data and reliability of the model has been analyzed. The calculated result is that calculated values using the kinetic model has a good agreement with the experimental values in which ethene and propene relative error is4.12%and3.54%respectively and all the other components relative errors are below10%.Finally, using the built kinetic model, change rule of MTO conversion, products yield and selectivity, catalyst activity which are affected by temperature, space-time, and water to methanol ratio in the feed has been investigated. It has been turned out that increasing reaction space-time could raise light olefins yield, but has not significantly influence on selectivity and could also decrease the catalyst deactivation rate. Increasing the temperature within certain limit could raise light olefins yield and selectivity but could accelerate the catalyst deactivation rate. At high temperature water to methanol ratio in the feed has a small influence on the light olefins yield and selectivity but could alleviate the catalyst deactivation rate. The research result could give a good guidance for the operation conditions optimization of industrial equipments in MTO process.