Development of New Kinetic Models for Methanol to Hydrocarbons over a Ca-ZSM-5 Catalyst

The reactions involved in methanol-to-hydrocarbon (MTH) conversion are complex and simultaneous. In this study, the influence of the temperature and weight hourly space velocity (WHSV) was investigated on the MTH kinetic model, which was built on the hydrocarbon pool mechanism using a catalyst of Ca-ZSM-5 (Ca-ZS-5). The existing kinetic model to describe the MTH process is a seven-lump model. The application of any kinetic model for the MTH reaction using the Ca-ZS-5 catalyst has not yet been studied. To obtain high accuracy, new kinetic models were constructed, namely, four- and eight-lump kinetic models. The four-lump model contained oxygenate, olefins, C5+ and paraffin. The eight-lump kinetic model included methanol, dimethyl ether, ethylene, propylene, butylene, C1-C4 (sum of CH4, C2H6, C3H8, i-C4H10, and n-C4H10), C5+ (sum of i-C5H12, n-C5H12, and 1-C5H12), and coke. The MTH experiment was performed at 673-773 K and WHSV values of 4.75, 9.5, and 14.25 h-1. The model simulation was carried out by fitting the model equation and experimental data to obtain kinetic parameters using MATLAB software. The results indicated that the four- and eight-lump kinetic models can accurately explain the behavior of the reaction kinetics, especially on the effect of the temperature and WHSV.