Michael J. Hanrahan

A study of the catalytically active copper species in the synthesis of methanol over CuCr oxide

Abstract CuCr oxide catalysts formulated with various Cu Cr ratios were prepared and evaluated as CH 3 OH synthesis catalysts. From the physical characterization of these catalysts by X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed desorption of CO, Cu + was identified as the active site responsible for CO chemisorption and CH 3 OH formation. The Cu + is stable under reaction conditions and exists as a crystalline CuCrO 2 phase. The concentration of surface Cu + (or CuCrO 2 ) is dependent upon the Cu Cr ratio, the calcination temperature, and the nature of the catalyst pretreatment.

Relationship between stable monovalent copper in copper–chromia catalysts and activity of methanol formation

The activity for methanol formation of copper-chromia catalysts is sensitive to the temperature of calcination pretreatment; X-rays photoelectron spectroscopic studies of the reduced catalysts showed a correlation between the amount of stable surface Cu+ and the activity for methanol formation.

Evidence for the stabilization of copper(I) in Cu-Cr oxide methanol catalysts

Abstract Cu-Cr oxide catalysts were studied to determine the nature of the active copper species in the synthesis of methanol from syngas. The surface electronic structure of the copper component in particular was investigated by X-ray photoelectron spectroscopy (XPS). A correlation was observed between the rate of methanol formation and the surface concentration of Cu+. Bulk stabilization of CuCrO2 (Cu+) appears to be correlated with surface-stabilized Cu+ species. High-temperature heating of Cu-Cr oxide catalysts enhances the formation of CuCrO2 at the catalyst surface, which is associated with increased methanol activity based upon normalized surface areas.

A Comparison Of The Dissolution Behavior Of Poly(P-Hydroxystyrene) With Novolac

An examination of the literature revealed that aqueous-processable positive-working photoresists based on novolac resins have been frequently reported, while analogous resists employing poly(p-hydroxystyrene) as the binder have not. In a functional resist formulation, poly(p-hydroxystyrene) would be expected to be similar to novolac in its development characteristics; however, this is not true. The dissolution properties of these two types of binders have been examined in order to identify the crucial differences. This paper presents the determination of the dissolution kinetic expression for both polymers. Additionally, the dissolution behavior of these materials in a resist-like environment is also discussed. From the results of our study, it can be concluded that poly(p-hydroxystyrene) does not exhibit as high a discrimination between exposed and unex-posed dissolution rates as does novolac.

Laser processing of chemically derived dichroic filters

Optical interference filters were fabricated using multilayer stacks derived from sol-gel SiO 2 and SiO 2 -TiO 2 coatings. Laser processing was then used to modify the spectral properties (color) of local regions of these stacks. Changes in color were analyzed with respect to changes in the individual film thicknesses and refractive indices. Design considerations and some basic limitations of laser firing for tuning interference filter colors are also discussed.

Laser processing of sol-gel-derived multilayer interference filters

Optical interference filters were fabricated using multilayers derived from sol-gel SiO2 and SiO2-TiO2 thin films. Laser processing was then used to modify the spectral properties of local regions of these stacks. The feasibility of using laser processing for selectively changing the optical properties of thin film devices was thus demonstrated. Design considerations and some basic limitations of this technique for tuning interference filter colors are then discussed.

Negative-Working E-Beam Copolymers

Copolymers of allyl methacrylate and propargyl methacrylate have very high speed as electron-beam and x-ray resists. They produce polymers of a structural complexity not often encountered in addition polymerization. The structural variety available in allyl methacrylate polymers gives them unusual properties, which consequently enhance their microlithographic performance.

Laser Processing of Multilayer Interference Filters

The use of lasers to modify the optical properties of multilayer interference filters is examined. The effects of laser firing on the optical properties of sol-gel deposited and electron-beam evaporated filters are compared experimentally. Filters made from sol-gel films are found to have tunability of at least 15%, while electron-beam evaporated filters are tunable by laser firing to less than 1%. This difference is explained by applying the Lorentz-Lorentz equation, which describes the effects of residual organics, water, and porosity in the sol-gel films on their optical properties. Possible routes to tailoring film microstructure and composition to optimize filter tunability are also discussed.