Selective Oxidation Catalysts

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This is actually a neat mechanical trick that at least alters theselectivity profile of specific oxide catalysts. This will certainlyimprove process yields for a range of applications which is alwayswelcome as that means sharply lowered costs.
With luck this can be tuned a great deal to affect many processes.
Obviously much more work should go into this field and include activemembranes and the like. The value is there even it it will always beterribly specific.
Researchers MakeStrides Toward Selective Oxidation Catalysts
by Staff Writers
Chicago IL (SPX)Nov 07, 2012
http://www.spacemart.com/reports/Researchers_Make_Strides_Toward_Selective_Oxidation_Catalysts_999.html
Oxide catalysts,typically formulated as powders, play an integral role in manychemical transformations, including cleaning wastewater, curbingtailpipe emissions, and synthesizing most consumer products. Greener,more efficient chemical processes would benefit greatly from solidoxide catalysts that are choosier about their reactants, butachieving this has proven a challenge.
Now researchers fromNorthwestern University and Argonne National Laboratory havedeveloped a straightforward and generalizable process for makingreactant-selective oxide catalysts by encapsulating the particles ina sieve-like film that blocks unwanted reactants.
The process could findapplications in energy, particularly the conversion of biomass intosugars and then fuels and other useful chemicals.
A paper detailing theresearch, "Shape-selective Sieving Layers on an Oxide CatalystSurface," was published October 28 in the journal NatureChemistry.
Especially forselective oxidation, "The ability to conduct these reactions ina selective way opens doors to new applications in green chemistryand sustainability," said Justin Notestein, assistant professorof chemical and biological engineering at Northwestern's McCormickSchool of Engineering and the paper's corresponding author.
"Unlike currentprocesses, which may require enzymes or precious metals, our methodrelies only on harmless, inert oxides. These are powders you can holdin your hand."
In testing theirmethod, the researchers focused on photocatalytic oxidations such asthe conversion of benzyl alcohol into benzaldehydes, reactions thatare notoriously unselective.
The researchers coateda core particle of titanium dioxide, a harmless white pigment, with ananometer-thick film of aluminum oxide. They used a synthesis methodthat resulted in a film pitted with tiny holes they dubbed"nanocavities," less than two nanometers in diameter.
This sieve-likecoating allowed only the smaller reactants in a mixture to slipthrough the holes and react with the titanium oxide, while largerreactants were blocked. The result was much higher selectivity (up to9:1) toward the less hindered reactants.
The process wasconducted at room temperature and required only a low-power lightsource, whereas other catalysts may require precious metals orhazardous oxidants.
In addition toNotestein, other Northwestern authors of the paper include Richard P.Van Duyne, professor of chemistry in Northwestern's Weinberg Collegeof Arts and Sciences; Peter C. Stair, professor and chair of thechemistry department in Weinberg; postdoctoral researcher ChristianP. Canlas; PhD candidate Natalie A. Ray; and undergraduate Nicolas A.Grosso-Giordano. From Argonne National Laboratory, authors includeJunling Lu, Sungsik Kee, Jeffrey W. Elam, and Randall E. Winans.
The research wasconducted in collaboration with the Institute for Atom-EfficientChemical Transformations, a Department of Energy Energy FrontierResearch Center that also includes members from Purdue University andthe University of Wisconsin.