Towards activity descriptors for the methane dehydroaromatization catalyst Mo/HZSM-

Abstract

In view of rising global demand for aromatics as starting chemical for many commodity goods as well as pharmaceuticals, new routes for production are explored. Since the advent of fracking, natural gas has become increasingly cheap and direct utilization for aromatics production has gained attractiveness. Methane dehydroaromatization represents the most direct of such utilization routes and could potentially be very carbon efficient, if no oxidants are added, since byproducts such as CO and CO2 are avoided. For the direct non-oxidative conversion however, fast deactivation due to coke formation and significant thermodynamic limitations still stand in the way of commercialization. Improvements of the catalysts towards coke-resistance and overall stability could significantly speed up the development towards large-scale operation of the methane dehydroaromatization process, although innovation in process development is also believed to be important. It is desirable to develop a catalyst that outperforms the state-of-the-art system Mo/HZSM-5. This system however, continues to perform better than other catalyst formulations, and for 25 years already, no significantly better system was found. Thus, this thesis focusses on developing a fundamental understanding of why this catalytic system continues to outperform other systems. The aim of this thesis was to spot the characteristic traits of this catalyst, which can then be used as guidelines for the development of novel catalysts.