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

Authors: 
Yang, Y., University of Pittsburgh
Akabua, E., University of Pittsburgh
Veser, G., University of Pittsburgh
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 800oC 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.