(476h) Oxidative Dehydrogenation of Ethane to Ethylene with Fe2O3@SiO2 Core@Shell Catalysts

The engineering of materials on the nanoscale enables precise tailoring of materials’ functionality. Core@shell materials are a widely studied class of engineered nanomaterials with application in various technologies. From a reaction engineering perspective, these nanocatalysts can be considered “nano-reactors” with porous membrane walls for preferential diffusion of molecules, which enables tuning of selectivity by tailoring the porosity of the shell material. Our previous studies have demonstrated the preferential diffusion and conversion of H₂ in H₂-CH₄ mixtures with lattice oxygen in NiO@SiO₂ due to a “sieving effect” by the porous SiO₂ matrix, confirming the potential of core@shell nanocatalysts towards tuning selectivity.

In the present work, we are extending this approach towards preferential oxidation of H₂ in H₂-C₂H₄/C₂H₆ mixtures to demonstrate the potential of such engineered core@shell materials for oxidative dehydrogenation of ethane to ethylene. Fe₂O₃@SiO₂ core@shell catalysts were synthesized, achieving with fine control of SiO₂ shell thickness with near nanometer precision by adjusting synthesis parameters, including SiO₂ precursor concentration and reaction time. This allows control of the degree of preferential diffusion and thus evaluation of the targeted selective conversion of hydrogen. The reactivity of these core@shell catalysts was evaluated by C₂H₆ pulse experiments at 800^oC to observe the gradual consumption of lattice oxygen in Fe₂O₃@SiO₂ in comparison to a conventional Fe₂O₃/SiO₂ catalyst as a reference. We observe noticeably reduced H₂ and CO₂ formation over the core@shell Fe₂O₃@SiO₂ catalyst, and a dependence of this effect on the shell thickness of the catalyst, strongly supporting our concept of selective H₂ oxidation due to “sieving” by the porous SiO₂ shell. Such core@shell materials hence open a relatively straightforward and rationally predictable approach towards designing selective catalysis based on well-established nanostructuring.