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Nanoporous membranes containing monodisperse pores of 24 nm diameter are fabricated using poly(styrene-b-lactide) block copolymers to template the pore structure. A 4 mum thin film of the block copolymer is cast onto a microporous membrane that provides mechanical reinforcement; by casting the copolymer film from the appropriate solvents and controlling the solvent evaporation rate, greater than 100 cm(2) of a thin film with polylactide cylinders oriented perpendicular to the thin dimension is produced. Exposing the composite membrane to a dilute aqueous base selectively etches the polylactide block, producing the porous structure. The ability of these pores to reject dissolved poly(ethylene oxide) molecules of varying molecular weight matches existing theories for transport through small pores.

Atomic layer deposition (ALD) of an alumina overcoat can stabilize a base metal catalyst (e.g., copper) for liquid-phase catalytic reactions (e.g., hydrogenation of biomass-derived furfural in alcoholic solvents or water), thereby eliminating the deactivation of conventional catalysts by sintering and leaching. This method of catalyst stabilization alleviates the need to employ precious metals (e.g., platinum) in liquid-phase catalytic processing. The alumina overcoat initially covers the catalyst surface completely. By using solid state NMR spectroscopy, X-ray diffraction, and electron microscopy, it was shown that high temperature treatment opens porosity in the overcoat by forming crystallites of γ-Al2 O3 . Infrared spectroscopic measurements and scanning tunneling microscopy studies of trimethylaluminum ALD on copper show that the remarkable stability imparted to the nanoparticles arises from selective armoring of under-coordinated copper atoms on the nanoparticle surface.

Recent advances in metabolic engineering have allowed for the production of a wide array of molecules via biocatalytic routes. The high selectivity of biocatalysis to remove functionality from biomass can be used to produce platform molecules that are suitable for subsequent upgrading over heterogeneous catalysts. Accordingly, the more robust continuous processing allowed by chemical catalysis could be leveraged to upgrade biologically derived platform molecules to produce direct or functional replacements for petroleum products. Herein, we highlight recent results that utilize a combination of chemical and biological catalysis, and using the perspective of heterogeneous chemical catalysis, we identify challenges that need to be addressed to bridge the gap between the two catalytic approaches. Specifically, studies are required to address the effects on catalyst performance of impurities that originate during bioprocessing. In addition, new generations of heterogeneous catalysts are required for stable operation under liquid phase reaction conditions in the presence of biogenic impurities. Finally, the design and syntheses of new catalysts are required to tailor the active sites and the environment around these sites to achieve selective conversion of the functional groups present in biologically derived platform molecules.

a b s t r a c tHigh-temperature calcination and reduction treatments of cobalt particles (17-20 nm) supported on TiO 2 create cobalt particles covered with a TiO y layer. The layer thickness ranges from 2.8 to 4.0 nm. These phenomena, commonly called strong metal-support interaction (SMSI), can be used to improve the catalyst stability and change the catalyst selectivity. For example, non-overcoated cobalt catalysts leached during aqueous-phase hydrogenation (APH) of furfuryl alcohol, losing 44.6% of the cobalt after 35 h time-on-stream. In contrast, TiO y -overcoated cobalt catalysts did not lose any measurable cobalt by leaching and the cobalt particle size remained constant after 105 h time-on-stream. The 1,5-pentanediol selectivity from furfuryl alcohol hydrogenolysis increased with increasing TiO y layer thickness. The stabilized cobalt catalyst also had high yields for APH of xylose to xylitol (99%) and APH of furfural to furfuryl alcohol (95%). These results show that the SMSI effect produces a catalyst with a similar structure as catalysts prepared by atomic layer deposition, thereby opening up a cheaper and more industrially relevant method of stabilizing base-metal catalysts for aqueous-phase biomass conversion reactions. In addition, the SMSI effect can be used to tune catalyst selectivity, thus allowing the more precise atomic scale design of supported metal catalysts.