Towards microfluidic reactors for in situ synchrotron infrared studies.

Anodically bonded etched silicon microfluidic devices that allow infrared spectroscopic measurement of solutions are reported. These extend spatially well-resolved in situ infrared measurement to higher temperatures and pressures than previously reported, making them useful for effectively time-resolved measurement of realistic catalytic processes. A data processing technique necessary for the mitigation of interference fringes caused by multiple reflections of the probe beam is also described.

Evolution of active catalysts for the selective oxidative dehydrogenation of methanol on Fe2O3 surface doped with Mo oxide.

Iron molybdate catalysts are used for the selective oxidation of methanol to formaldehyde. In this paper we have attempted to understand what determines high selectivity in this reaction system by doping haematite with surface layers of Mo by incipient wetness impregnation. This works well and the Mo appears to form finely dispersed layers. Even very low loadings of Mo have a marked effect on improving the selectivity to formaldehyde. Haematite itself is a very poor catalyst with high selectivity to combustion products, whereas, when only 0.25 monolayers of Mo are deposited on the surface, formaldehyde and CO selectivities are greatly enhanced and CO2 production is greatly diminished. However, even with as much as seven monolayers of Mo dosed on to the surface, these materials achieve much less selectivity to formaldehyde at high conversion than do the industrial catalysts. The reason for this is that the Mo forms a 'skin' of ferric molybdate on a core of iron oxide, but does not produce a pure Mo oxide monolayer on the surface, a situation which is essential for very high yields of formaldehyde.

Preparation, structure, and stability of Pt and Pd monolayer modified Pd and Pt electrocatalysts.

A controlled surface reaction technique has been successfully employed to prepare a series of Pt modified Pd/C (Pt/Pd/C) and Pd modified Pt/C (Pd/Pt/C) catalysts. The resulting catalyst materials were characterised by TEM, XRD, electrochemistry, and EXAFS techniques. In the case of the Pd/Pt/C carbon catalysts, core-shell structural arrangements were found, with a 0.04 A contraction of the Pd-Pd bond distance for the 1 Pd/Pt/C being observed. A greater degree of alloying was found for the Pt/Pd/C catalysts where the surface had a mixed composition with a large proportion of the Pt in the interior of the nanoparticle. However, strong Pt characteristics were exhibited in the voltammetry of Pt/Pd/C catalysts, most notably a large increase in the stability with respect to the electrochemical environment compared to Pd alone.