Single-Atom Pt with Significantly Boosted Performance by Mesoporous Hollow Ceria Support for Dehydrogenation of
Shenghui Zhou1,2, Mohammadreza Kosari3, Hossein Akhoundzadeh1
1School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459, Singapore.
Abstract:
Methylcyclohexane/toluene (MCH/TOL) is a promising liquid organic hydrogen carrier (LOHC) due to their low toxicity and compatibility with existing fossil fuel infrastructure. Developing high-performance and economical catalysts for H2 release from MCH is crucial for practical applications. Previously reported Pt single-atom catalysts (SACs) with loading up to 0.15 wt% are either nearly inactive or exhibit limited cycloalkane dehydrogenation conversions under realistic space velocities. Here, we successfully synthesized mesoporous hollow ceria-supported Pt SACs (Pt1/mh-CeO2) with tunable Pt loadings of 0.1-0.75 wt%, which operate efficiently under carrier-gas-free industrial conditions. At 0.25 wt% Pt loading, an exceptionally high hydrogen evolution rate of 4705 mmol·gPt -1·min-1 can be obtained near the kinetic region (25% MCH conversion). Under a more realistic condition with 94% conversion, the same catalyst still affords high apparent hydrogen evolution rate of 3106 mmol·gPt -1·min-1 with good stability, markedly surpassing previously reported Pt catalysts. The significantly boosted performance of Pt SACs by mesoporous hollow ceria is attributed to (i) accessible Pt single-sites, (ii) enhanced mass transfer for large C6-ring molecules with kinetic sizes smaller than the pore dimensions, and (iii) promoted MCH adsorption/activation on isolated Pt sites anchored on ceria with rich oxygen vacancies, as evidenced by vapor diffusion experiment and dynamics simulations.
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