Impact of the location of magnesium in zeolite-based shaped catalyst bodies on the methanol-to-hydrocarbons process

Abstract

One of the main challenges for the chemical industries is finding new ways to produce lower olefins, such as propylene and ethylene, to satisfy the increase in demand for e.g., polymers, namely polypropylene and polyethylene. The Methanol-to-Hydrocarbons (MTH) process is an alternative manufacturing process that can help to address this increasing demand for these important chemical building blocks. It has been proposed that the addition of magnesium to zeolites, in the form of powdered catalyst materials, enhances the selectivity towards light olefins. In this work, the impact of the location of magnesium (present as Mg2+ and MgO) in zeolite-based shaped catalyst bodies on their physicochemical properties and catalytic performance in the MTH reaction has been studied. By adjusting one of the preparation steps of the overall extrusion process in which magnesium is added tuning the location of magnesium, higher interaction between magnesium and the zeolite material could be achieved. Pre-extrusion modification showed the most favorable results in terms of physicochemical properties and catalytic activity. We found that the magnesium location could be crucial for altering molecular transport, coke formation, and catalyst deactivation during the MTH reaction due to its pronounced effects on the acidity as well as porosity of the shaped catalyst bodies. These new insights can be applied to other zeolite-based extrudate materials and other acid-catalyzed reactions as it can be crucial for the design of better and more efficient catalyst materials in their industrially shaped form.