A seven lumped kinetic model for industrial catalyst in DMTO process

Abstract

Methanol to olefins (MTO) represents an important process for ethylene and propylene production from abundant natural materials, e.g. natural gas or biomass. This paper reports a lumped kinetic model for the MTO process over an industrial MTO catalyst, i.e. DMTO catalyst. The kinetic model takes into account seven lumps, i.e. methane, ethylene, propylene, propane, C4, C5+ (including C5, C6 hydrocarbons and ethane) and coke. And a selective deactivation model was proposed to quantify the product selectivity and abrupt activity change in the MTO process. The kinetics under temperatures of 450°C, 475°C, and 490°C, water/methanol mole ratio in the feed of 0, 2 and 4, and weight hour space velocity (WHSV) between 30 and 955gMeOHgcat−1h−1 was studied. Experiments with small WHSV of 2.1 and 2.8gMeOHgcat−1h−1 were further carried out to study the catalyst deactivation. The kinetic parameters were calculated by use of a nonlinear least square method, with special attention to the coke distribution along the axial distance. The proposed kinetic model is able to predict the product concentrations measured in the fixed bed reactor reasonable well, with relative deviations less than 5% for major species such as ethylene, propylene, butylenes and methanol.