Reaction and deactivation kinetics of methanol-to-olefins process based on a special TGA reactor

Thermax 700 thermo gravimetric analysis (TGA) instrument is introduced for the investigation of the reaction and deactivation kinetics of Methanol-to-Olefins (MTO) process with SAPO-34 catalyst. By the use of a special sample basket, the TGA instrument can be viewed as a plug flow fixed-bed reactor, while the weight change of SAPO-34 during reaction can be recorded online. Kinetic data are acquired in the temperature range of 648.2-748.2 K and space velocities of 7.08-35.91 h(-1) (WHSV). Catalyst activity is expressed with average coke content, and selectivity for different products is related as a function of coke content and temperature. Methane is also introduced into the lumping kinetic model, and power exponent function with first-order reaction is adopted for model deduction. Exponential function is tested to give the best fit for catalyst activity and product selectivity with the highest correlation coefficient. The nicely agreed results between experimental and calculated data suggest that the overall kinetic model would be meaningful in both product distribution prediction and reactor simulation.