The liquid organic hydrogen carrier (LOHC) 2-(N-methylbenzyl)pyridine (MBP) shows good potential for H storage based on reversible hydrogenation and dehydrogenation, with an H storage density of 6.15 wt %. This material and the corresponding perhydro product (H -MBP) are liquids at room temperature. Remarkably, H release is much faster from H -MBP over Pd/C than from the benchmark perhydro benzyltoluene over Pt/C at lower temperatures than 270 °C, owing to the addition of N atom into the benzene ring. Since this positive effect is unfavorable to the hydrogenation reaction, more Ru/Al O catalyst or prolonged reaction time must be applied for complete H storage. Experiments with repeated hydrogenation-dehydrogenation cycles reveal that reversible H storage and release are possible without degradation of the MBP/H -MBP pair. The prepared MBP satisfies the requirements for chemical stability, handling properties, and cytotoxicity testing.
The activity and stability of supported Pd catalysts are of crucial importance in the dehydrogenation of perhydro 2‐(n‐methylbenzyl)pyridine (H12‐MBP) reported as a potential liquid organic hydrogen carrier. Because of good stability examined in many hydroprocessing reactions, carbon‐coated alumina (CCA) was chosen as a support for Pd loading and prepared by the pyrolysis of glycerol solution with different concentrations. The catalytic activity and stability of Pd/CCA catalysts exhibited a volcano‐shaped relationship with the carbon content. Various characterization results revealed that the degree of carbon coating affected the acidity, Pd loading and particle size, reactant adsorption capacity, and H2 release at low temperatures. At an optimal carbon content (3.3 wt % in this work), these properties are believed to be balanced well, thus showing the best catalytic performance. Moreover, the improvement of catalytic activity was examined with supported Pd on carbon‐coated silica‐alumina of 3.3 wt % carbon content.
Herein, nanoporous Al2O3, CeO2, TiO2, ZrO2,
and SnO2 were used
as the supports for Pd nanoparticles, and effects of surface characteristics
on catalytic performances for dehydrogenation of 2-[(n-methylcyclohexyl)methyl]piperidine (H12-MBP) as the H2-rich liquid organic hydrogen carrier were investigated. The
H2 yield, dehydrogenation rate, product selectivity, and
recyclability of the supported Pd catalysts depended on the metal
oxide support and Pd loading. The H2 yield and reaction
rate of the Al2O3 supporting 5 wt % Pd with
a mean size of 5.76 nm were the highest (75.8%) and the fastest (k
1
= 0.076 min–1), respectively, of all the catalysts. CeO2 exhibited
the highest reducibility and the best supporting ability for Pd nanoparticles,
which thus dispersed Pd with the smallest mean size of 3.45 nm. Although
this catalyst exhibited a lower H2 yield (67.1%) and a
slower reaction rate (k
1
= 0.030 min–1) than Al2O3, it showed the best recyclability without a significant loss of
activity during four consecutive runs, which could be attributed to
the strong metal–support interaction of Pd to the surface of
CeO2. The H2 yield and the dehydrogenation rate
were systematically correlated with the surface characteristics of
the metal oxides, such as acidity, adsorption affinity (adsorption
energy), and charge transfer value of H12-MBP, which were
determined via combined experimental and theoretical studies.
A hollow nanoreactor suitable for the cultivation of Ni-nanocrystals was developed through a distinct seed-engineering stratagem, which involved the assembly of a catalytically active Au/Pd-heterojunction-nanocrystal inside the hollow silica nanoshell. The resulting hollow nanoreactor demonstrated a targeted performance in the cavity-confined growth of the catalytic Ni nanocrystal.
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