Tunable Ptδ+/Pt0 sites by highly dispersed defected TiO2 for efficient catalytic methylcyclohexane dehydrogenation

Dehydrogenation reaction occurs for the hydrogen release process of liquid organic hydrogen carriers (LOHCs), the regenerative cooling of advanced aircraft, etc. But the synergistic effects of Pt active sites are still ambiguous. Herein, a series of Pt-based catalysts with tunable Pt 0 -Pt δ+ sites were fabricated by changing the ratio of highly dispersed defected TiO 2 on MCM-41 (M41) for efficient dehydrogenation of methylcyclohexane (MCH). The characterizations indicate TiO 2 nanoparticles (NPs) are highly dispersed on M41 support, and possess abundant Ti 3+ /oxygen vacancies. The increase of TiO 2 loading amount can enhance the interaction between Pt NPs and TiO 2 , which increases Pt δ+ /Pt 0 ratio gradually. The dehydrogenation test and theoretical results confirm that the synergistic effect of Pt 0 and Pt δ+ sites contributes the optimal dehydrogenation performance, in which Pt 0 promotes the consecutive C–H bond cleavage and Pt δ+ significantly decreases the desorption energy barrier for H 2 and toluene (TOL). Specifically, the MCH conversion (when applied for LOHCs) is ca. 88 % and the selectivity of TOL is over 99.5 % under 1.0Pt/0.5TiO 2 /M41, while the high MCH conversion of 90 % and TOL selectivity of more than 86 % are achieved under 1.0Pt/1.0TiO 2 /M41 (as regenerative cooling for hypersonic vehicle). This work provides the approach of modulating the synergistic active sites to obtain high-performance dehydrogenation catalyst.