The recent shale gas revolution offers exciting opportunities to meet global demands with new solutions. Increasing demand for ethylene, one of the worldâs most produced chemicals, presents such an opportunity. While traditionally generated through naphtha cracking, ethylene may also be produced through the dehydrogenation of ethane present in shale gas. To enable the economic feasibility of this process, studies
1 screened numerous candidate catalysts and discovered alumina-supported gallium (Ga/Al
2O
3) as a highly promising material. However, its impressive catalytic activity is inhibited by deactivation due to coking. Attempting to prevent this deactivation while retaining dehydrogenation activity, multiple investigations
2,3 explored coking mitigation strategies, such as CO
2 co-feeding, but we have yet to understand the complete, underlying kinetics and unlock the potential of this exciting catalyst.
In this work, we investigate the kinetics of ethane dehydrogenation over Ga/Al2O3 and the associated deactivation. Analyzing our micro gas chromatography data with novel Bayesian techniques, we ascertain a layered reaction network and associated kinetic parameters. We discover a fundamental change stemming from the water produced that selectively affects ethane dehydrogenation but not the unwanted side reaction of hydrogenolysis. This water effect also applies to the deactivation kinetics and explains CO2 co-feeding inhibiting coking through the surprising lens of the reverse water-gas shift reaction. Applying these findings alongside additional experiments exploring water co-feeding, we identify a promising path towards substantial conversion, improved selectivity, and negligible coking. These discoveries offer novel insights into this promising catalyst and general applicability to similar oxide materials.
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