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

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...

Quantifying the impact of dispersion, acidity and porosity of Mo/HZSM-5 on the performance in methane dehydroaromatization

The catalytic performance of the bifunctional catalyst Mo/HZSM-5 for methane dehydroaromatization (MDA) depends on the Mo dispersion and on zeolite acidity. Here we separately quantify the effect of dispersion and the effect of acidity on aromatic yields and coke selectivity. Also, the effect of porosity on the same is quantitatively...

Structure and Reactivity of the Mo/ZSM-5 Dehydroaromatization Catalyst: An Operando Computational Study

Mo/ZSM-5 is one of the most studied and efficient catalysts for the dehydroaromatization of methane (MDA), but the mechanism of its operation remains controversial. Here, we combine an ab initio thermodynamic analysis with a comprehensive mechanistic density functional theory study to address Mo-speciation in the zeolite and identify the...

A site-sensitive quasi-in situ strategy to characterize Mo/HZSM-5 during activation

The active sites on the methane dehydroaromatization (MDA) catalyst Mo/HZSM-5 are very hard to characterize, because they are present in various geometries and sizes and only form under reaction conditions with methane at 700 °C. To address these issues an experimental strategy is presented that enables distinguishing different active sites...

Progress in Developing a Structure-Activity Relationship for the Direct Aromatization of Methane

To secure future supply of aromatics, methane is a commercially interesting alternative feedstock. Direct conversion of methane into aromatics combines the challenge of activating one of the strongest C-H bonds in all hydrocarbons with the selective aromatization over zeolites. To address these challenges, smart catalyst and process design...

On the dynamic nature of Mo sites for methane dehydroaromatization

The mechanism of methane activation on Mo/HZSM-5 is not yet fully understood, despite the great interest in methane dehydroaromatization (MDA) to replace aromatics production in oil refineries. It is difficult to assess the exact nature of the active site due to fast coking. By pre-carburizing Mo/HZSM-5 with carbon monoxide (CO), the MDA active...

Relevance of the Mo-precursor state in H-ZSM-5 for methane dehydroaromatization

Although the local geometry of Mo in Mo/HZSM-5 has been characterized before, we present a systematic way to manipulate the configuration of Mo and link it to its catalytic properties. The location and geometry of cationic Mo-complexes, the precursor of the active metal site for methane dehydroaromatization, are altered by directing the way...