(344e) Catalyst Deactivation Study during Microwave-Assisted Methane Dehydroaromatization

Flaring of natural gas continues to be both an environmental and economic problem in the United States. Microwave-assisted reactions could offer a novel non-traditional approach in catalyst activation and product selectivity compared to a traditional thermal approach and can be developed into compact, modular systems for flare gas conversion at the well site. Due to thermodynamic limitation and poor catalyst stability for the methane dehydroaromatization reaction for aromatics production, understanding the catalyst deactivation would be beneficial towards designing a robust microwave catalyst. In this work, we studied the catalyst (Mo/HZSM-5) deactivation at different catalytic stages of performance from activation through deactivation. A comparison between microwave and conventional thermal reaction showed that the microwave-assisted methane dehydroaromatization reaction overperformed the conventional reaction towards aromatic yield but has shown to be less stable. These results could be due to formation of microwave hotspots on the catalyst surface inducing either more carbon formation or affecting the carbon due to the strong coupling which dehydrogenates the carbon to become more refractory and less reactive. In both cases this would cause rapid deactivation under microwaves. Different characterization tools were used to determine the activity-structure relationship, such as XPS, TPO, SEM-EDS, NH3-TPD, XRD, and dielectric properties for fresh and reacted catalysts.