Design and synthesis of copper-cobalt catalysts for the selective conversion of synthesis gas to ethanol and higher alcohols.

Combining quantum-mechanical simulations and synthesis tools allows the design of highly efficient CuCo/MoO(x) catalysts for the selective conversion of synthesis gas (CO+H2) into ethanol and higher alcohols, which are of eminent interest for the production of platform chemicals from non-petroleum feedstocks. Density functional theory calculations coupled to microkinetic models identify mixed Cu-Co alloy sites, at Co-enriched surfaces, as ideal for the selective production of long-chain alcohols. Accordingly, a versatile synthesis route is developed based on metal nanoparticle exsolution from a molybdate precursor compound whose crystalline structure isomorphically accommodates Cu(2+) and Co(2+) cations in a wide range of compositions.

Catalytic aromatization of methane.

Recent developments in natural gas production technology have led to lower prices for methane and renewed interest in converting methane to higher value products. Processes such as those based on syngas from methane reforming are being investigated. Another option is methane aromatization, which produces benzene and hydrogen: 6CH4(g) → C6H6(g) + 9H2(g) ΔG°(r) = +433 kJ mol(-1) ΔH°(r) = +531 kJ mol(-1).

Ligand-stabilized and atomically precise gold nanocluster catalysis: a case study for correlating fundamental electronic properties with catalysis.

We present results from our investigations into correlating the styrene-oxidation catalysis of atomically precise mixed-ligand biicosahedral-structure [Au25(PPh3)10(SC12H25)5Cl2](2+) (Au25-bi) and thiol-stabilized icosahedral core-shell-structure [Au25(SCH2CH2Ph)18](-) (Au25-i) clusters with their electronic and atomic structure by using a combination of synchrotron radiation-based X-ray absorption fine-structure spectroscopy (XAFS) and ultraviolet photoemission spectroscopy (UPS). Compared to bulk Au, XAFS revealed low Au-Au coordination, Au-Au bond contraction and higher d-band vacancies in both the ligand-stabilized Au clusters. The ligands were found not only to act as colloidal stabilizers, but also as d-band electron acceptor for Au atoms.

Millifluidics for time-resolved mapping of the growth of gold nanostructures.

Innovative in situ characterization tools are essential for understanding the reaction mechanisms leading to the growth of nanoscale materials. Though techniques, such as in situ transmission X-ray microscopy, fast single-particle spectroscopy, small-angle X-ray scattering, etc., are currently being developed, these tools are complex, not easily accessible, and do not necessarily provide the temporal resolution required to follow the formation of nanomaterials in real time.

Nitrogen-doped fullerene as a potential catalyst for hydrogen fuel cells.

We examine the possibility of nitrogen-doped C60 fullerene (N-C60) as a cathode catalyst for hydrogen fuel cells. We use first-principles spin-polarized density functional theory calculations to simulate the electrocatalytic reactions on N-C60. The first-principles results show that an O2 molecule can be adsorbed and partially reduced on the N-C complex sites (Pauling sites) of N-C60 without any activation barrier.

Synthesis, characterization, and testing of supported Au catalysts prepared from atomically-tailored Au38(SC12H25)24 clusters.

Nearly monodispersed Au(38)(SC(12)H(25))(24) clusters (1.7 ± 0.2 nm) were synthesized using a modified Brust process while utilizing a "thiol etching" approach for the ligand exchange.

Direct conversion of methane to higher hydrocarbons using AlBr3-HBr superacid catalyst.

The direct gas phase catalytic oligomerization of methane at temperatures ≤673 K has been demonstrated using AlBr(3)-HBr superacid. The reaction produces C(2)+ hydrocarbons and hydrogen in a single step at 1 atm in a continuous flow reactor at a nominal residence time of 60 s. The essentially complete conversion of methane appears to be due to protolytic activation of methane in the presence of H(+)AlBr(4)(-).

Heterogeneous catalytic synthesis of ethanol from biomass-derived syngas.

The selective catalytic conversion of biomass-derived syngas into ethanol is thermodynamically feasible at temperatures below roughly 350 degrees C at 30 bar. However, if methane is allowed as a reaction product, the conversion to ethanol (or other oxygenates) is extremely limited. Experimental results show that high selectivities to ethanol are only achieved at very low conversions, typically less than 10%.