Mechanistic and kinetic investigations on the role of methanol and dimethyl ether in the Methanol-To-Hydrocarbons reaction

This PhD thesis deeply analyzes the mechanistic and kinetic behavior of methanol and dimethyl ether (DME) in the industrially relevant Methanol-To-Hydrocarbons (MTH) reaction, which employs zeolitic materials as catalysts. Industrial MTH processes use methanol, DME or combined methanol/DME feeds over zeolitic catalysts. Methanol and its dehydration product, DME, are conventionally attributed an analogous behavior in MTH; however, a thorough investigation on the theme was missing even though the MTH reaction has been studied for 40 years already. By means of mechanistic and kinetic studies, methanol has been found to negatively impact catalyst stability as compared to DME. This is rationalized based on the ability of methanol to form formaldehyde, a molecule that can act as coke promoter. Furthermore, the work presented in this PhD thesis suggest different strategies to reduce the impact of methanol on catalyst deactivation, thereby optimizing the lifetime of the catalyst during MTH operation