A simple and inexpensive approach is used to coat metal oxide surfaces (SBA-15) with thin films of carbon. These carbon films provide improved hydrothermal stability to oxides, such as silica and alumina, which are not otherwise stable at elevated temperatures in the presence of liquid water. Furthermore, the carbon film changes the surface chemistry of the support.

Commercial mesoporous oxides, such as silica, are not stable in liquid-phase reactions, particularly aqueous-phase reactions at elevated temperatures, which are corrosive to oxide supports. We have shown previously that the hydrothermal stability of silica is significantly improved by coating the surface with thin carbon layers. Herein, we show that controlled pyrolysis of sugars also provides a facile approach for coating supported metal catalysts, leading to improved dispersion of the active metal phase in the hydrothermally aged catalyst. The carbon overcoats are synthesized at mild temperatures, resulting in an open structure, as revealed by 13C NMR, which helps explain why the overcoats do not significantly block the active sites. We compare two approaches–depositing Pd on carbon-coated silica and depositing carbon overcoats on Pd/silica. The carbon overcoating approach leads to better performance after hydrothermal aging, as determined by using a probe reaction (CO oxidation) to quantify the number of active sites. The efficacy of the carbon overcoating was demonstrated by the improved stability of Pd/silica catalysts for aqueous phase acetone hydrogenation. Likewise, carbon-overcoated Cu/alumina catalyst was found to be more stable for aqueous-phase furfural hydrogenation compared with the uncoated catalyst.

The trivalent metal cations Al(3+) , Cr(3+) , and Fe(3+) were each introduced, together with Sc(3+) , into MIL-100(Sc,M) solid solutions (M=Al, Cr, Fe) by direct synthesis. The substitution has been confirmed by powder X-ray diffraction (PXRD) and solid-state NMR, UV/Vis, and X-ray absorption (XAS) spectroscopy. Mixed Sc/Fe MIL-100 samples were prepared in which part of the Fe is present as α-Fe2 O3 nanoparticles within the mesoporous cages of the MOF, as shown by XAS, TGA, and PXRD. The catalytic activity of the mixed-metal catalysts in Lewis acid catalysed Friedel-Crafts additions increases with the amount of Sc present, with the attenuating effect of the second metal decreasing in the order Al>Fe>Cr. Mixed-metal Sc,Fe materials give acceptable activity: 40 % Fe incorporation only results in a 20 % decrease in activity over the same reaction time and pure product can still be obtained and filtered off after extended reaction times. Supported α-Fe2 O3 nanoparticles were also active Lewis acid species, although less active than Sc(3+) in trimer sites. The incorporation of Fe(3+) into MIL-100(Sc) imparts activity for oxidation catalysis and tandem catalytic processes (Lewis acid+oxidation) that make use of both catalytically active framework Sc(3+) and Fe(3+) . A procedure for using these mixed-metal heterogeneous catalysts has been developed for making ketones from (hetero)aromatics and a hemiacetal.

The versatility of MOFs as highly porous Lewis acidic supports for precious metal nanoparticles has been exploited for one-pot tandem reductive amination catalysis. MIL-101(Cr) loaded with Pd nanoparticles ca. 3 nm in size at 0.2–1 wt% has been used to catalyse the reaction of 4′-fluoroacetophenone with benzylamine under 10 bar of H 2 to give the secondary amine, 4′-fluoro-α-methyl- N -phenylmethylbenzenemethanamine. For the highest Pd loading, major hydrogenolysis of the secondary amine occurs in a second tandem reaction, but by changing the ratio of Pd to Lewis acidic Cr 3+ active sites it is possible to tune the catalytic selectivity to the desired 2° amine product. An empirical kinetic analysis was performed to demonstrate this active site complementarity. Graphical Abstract Electronic supplementary material The online version of this article (doi:10.1007/s10562-017-2208-0) contains supplementary material, which is available to authorized users.

As participants monitored more patients in a laboratory setting, their performance with respect to recognizing critical and noncritical events declined. This study has implications for the design of remote telemetry work and other patient monitoring tasks in critical and intermediate care units.