Conversion of Methanol to Lower Olefins. Kinetic Modeling, Reactor Simulation, and Selection

Reactor types of commercial-scale methanol-to-olefins (MTO) processes in the ethene mode, using a small-pore molecular-sieve catalyst, have been evaluated both qualitatively and quantitatively. A kinetic model has been developed via an iterative process of model formulation, parameter estimation, and model validation. The final model consists of 12 reactions involving 6 component lumps plus coke. Important factors are the occurrence of consecutive reactions and the effect of coke on both the activity and selectivity. This kinetic model has been implemented in mathematical models of various reactors for the estimation of product selectivities and main reactor dimensions. These formed the basis for a comparison of different reactor types for a commercial-scale process. A circulating fast fluidized-bed reactor and a turbulent fluidized-bed reactor emerged as the most promising reactor systems for MTO in the ethene mode; ethene/propene ratios of 1-1.5 can be achieved with realistic reactor dimensions.