Reversible dehydrogenation and rehydrogenation of cyclohexane and methylcyclohexane by single-site platinum catalyst

Abstract

Developing highly efficient and reversible hydrogenation-dehydrogenation catalysts shows great promise for hydrogen storage technologies with highly desirable economic and ecological benefits. Herein, we show that reaction sites consisting of single Pt atoms and neighboring oxygen vacancies (VO) can be prepared on CeO2 (Pt1/CeO2) with unique catalytic properties for the reversible dehydrogenation and rehydrogenation of large molecules such as cyclohexane and methylcyclohexane. Specifically, we find that the dehydrogenation rate of cyclohexane and methylcyclohexane on such sites can reach values above 32,000 molH2 molPt−1 h−1, which is 309 times higher than that of conventional supported Pt nanoparticles. Combining of DRIFTS, AP-XPS, EXAFS, and DFT calculations, we show that the Pt1/CeO2 catalyst exhibits a super-synergistic effect between the catalytic Pt atom and its support, involving redox coupling between Pt and Ce ions, enabling adsorption, activation and reaction of large molecules with sufficient versatility to drive abstraction/addition of hydrogen without requiring multiple reaction sites.

CO-tolerant RuNi/TiO2 catalyst for the storage and purification of crude hydrogen

“…Previous attempts showed that by decreasing the size of metal to atomic scale, the resulting cationic metal single atoms with less d-electrons tend to bind CO in a less intensive manner 12 – 15 . As for the hydrogenation of aromatic substrate which generally requires metal ensemble sites 16 – 20 , Su et al recently discovered that with the assistance of neighboring oxygen vacancies, Pt single atom catalyst manifests even higher toluene hydrogenation performance than catalysts with Pt nanoparticles (NPs) 21 . Despite the theoretical potential of single atom catalysts in driving the CO-tolerant toluene hydrogenation process, their attenuated interaction toward CO would inevitably compromise the purification capabilities toward the crude hydrogen feed.…”

Hydrogen Generation from Organic Hydrides under Continuous‐Flow Conditions Using Polymethylphenylsilane‐Aluminum Immobilized Platinum Catalyst

“…Dehydrogenation of MCH and heterocyclic compounds was conducted in a fixed‐bed flow type reactor in recently reported articles [3d,e,h] . In these reports, mixture of substrate and inert gas (Ar or N 2 ) was streamed generally, because dilution of generated hydrogen by inert gas could shift the equilibrium toward dehydrogenation.…”

Toward a Hydrogen Economy: Development of Heterogeneous Catalysts for Chemical Hydrogen Storage and Release Reactions

“…213 Recently, Prendergast, Somorjai, and Su reported a SAC based on Pt 1 / CeO 2 which greatly enhanced the reaction rate of cyclohexane dehydrogenation. 214 More specifically, the activity of this catalyst system was 300-fold higher than that of conventional NPs catalysts (Pt/CeO 2 and Pt/Al 2 O 3 ). Moreover, this SAC was applicable in the MCH/toluene system.…”

“…To achieve activity, the catalyst precursor (PdO/CeO 2 ) must be pretreated at reducing conditions (H 2 , 200 °C, 1 h) . Recently, Prendergast, Somorjai, and Su reported a SAC based on Pt 1 /CeO 2 which greatly enhanced the reaction rate of cyclohexane dehydrogenation . More specifically, the activity of this catalyst system was 300-fold higher than that of conventional NPs catalysts (Pt/CeO 2 and Pt/Al 2 O 3 ).…”