Al2O3 precursor-driven defect-rich surface for tailored Pt–support interaction enabling efficient and selective LOHC dehydrogenation

초록

Metal–support interaction (MSI) in Pt/Al2O3 catalysts for dehydrogenation of liquid organic hydrogen carrier tailors Pt site distribution that greatly influences H2 productivity and product selectivity. While post-synthetic modifications are widely utilized for Al2O3, complementing with precursor-based approaches provides further opportunities for regulating specific surface defects. Here we report a defect-rich Al2O3 framework that is produced through a series of salt (NH4NO3) removal and thermal treatment for a precursor of mesoporous alumina (mA) prepared by solvent-deficient precipitation. The defects present in the produced mA(R) support serve as stabilized Pt anchoring sites through strong MSI, suppressing the formation of Pt terrace sites different from the conventional particle growth principle. The resulting catalyst Pt/mA(R) exhibits higher Pt utilization than other counterparts in dehydrogenation of perhydro-benzyltoluene (H12-BT) to benzyltoluene (H0-BT), outperforming Pt/γ-Al2O3 in H2 productivity and methylfluorene (MF) selectivity across all examined Pt loadings. Particularly, 0.5 wt% Pt/mA(R) shows a turnover frequency of 36.2 min−1 (ca. 3.3 times higher than 0.5 wt% Pt/γ-Al2O3) and MF formation limited to 50–60% of Pt/γ-Al2O3 at the comparable activity level. This enhanced intrinsic activity together with superior H2 productivity (18.8 gH2 gPt−1 at 250 °C and 220 min) is maintained over three recycle tests, demonstrating that the defect-anchored Pt sites promote C–H activation in H12-BT and prevent further dehydrogenation of H0-BT. Therefore, Al2O3 precursor-based control of surface defects can modulate Pt–Al2O3 interaction toward enhanced site accessibility, thereby maximizing Pt utilization for robust catalytic performance.

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