Oxygenates, properties methanol

Numerous chemical intermediates are oxygen rich. Methanol, acetic acid and ethylene glycol show a O/C atomic ratio of 1, as does biomass. Other major chemicals intermediates show a lower O/C ratio, typically between 1/3 and 2/3. This holds for instance for propene and butene glycols, ethanol, (meth)acrylic acids, adipic acid and many others. The presence of some oxygen atoms is required to confer the desired physical and chemicals properties to the product. Selective and partial deoxygenation of biomass may represent an attractive and competitive route compared with the selective and partial oxidation of hydrocarbon feedstock. 

Activity Measurements. To test catalytic properties of various samples partial oxidation of methanol to formaldehyde was studied in a flow micro-reactor operating under normal atmospheric pressure (10). For each run about 0.2 g of catalyst sample was used and the activities were measured at 173 C in the absence of any diffusional effects. The feed gas consisted of 72, 2 and by volume of nitrogen, oxygen and methanol vapor respectively. Reaction products were analysed with a 10% Carbowax 20 M column (2m long) maintained at 60 C oven temperature. 

Films or membranes of silkworm silk have been produced by air-drying aqueous solutions prepared from the concentrated salts, followed by dialysis (11,28). The films, which are water soluble, generally contain silk in the silk I conformation with a significant content of random coil. Many different treatments have been used to modify these films to decrease their water solubiUty by converting silk I to silk II in a process found usehil for enzyme entrapment (28). Silk membranes have also been cast from fibroin solutions and characterized for permeation properties. Oxygen and water vapor transmission rates were dependent on the exposure conditions to methanol to faciUtate the conversion to silk II (29). Thin monolayer films have been formed from solubilized silkworm silk using Langmuir techniques to faciUtate stmctural characterization of the protein (30). ResolubiLized silkworm cocoon silk has been spun into fibers (31), as have recombinant silkworm silks (32). 

Oxygen was added as oxygenated hydrocarbon components methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE), ethanol, methanol, and tertiary butyl alcohol (TBA). The properties of oxygenates, as they relate to gasoline blending, are shown in Table 10-1. 

We have already referred to the Mo/Ru/S Chevrel phases and related catalysts which have long been under investigation for their oxygen reduction properties. Reeve et al. [19] evaluated the methanol tolerance, along with oxygen reduction activity, of a range of transition metal sulfide electrocatalysts, in a liquid-feed solid-polymer-electrolyte DMFC. The catalysts were prepared in high surface area by direct synthesis onto various surface-functionalized carbon blacks. The intrinsic... 

Ozenler SS, Kadirgan F (2006) The effect of the matrix on the electro-catalytic properties of methanol tolerant oxygen reduction catalysts based on ruthenium-chalcogenides. J Power Sources 154 364-369... 

The steady state experiments showed that the two separate phases and the mixture are not very different in activity, give approximately the same product distributions, and have similar kinetic parameters. The reaction is about. 5 order in methanol, nearly zero order in oxygen, and has an apparent activation energy of 18-20 kcal/mol. These kinetic parameters are similar to those previously reported (9,10), but often ferric molybdate was regcirded to be the major catalytically active phase, with the excess molybdenum trioxide serving for mechanical properties and increased surface area (10,11,12). 

For the study of the electrocatalytic reduction of oxygen and oxidation of methanol, our approach to the preparation of catalysts by two-phase protocol " provides a better controllability over size, composition or surface properties in comparison with traditional approaches such as coprecipitation, deposition-precipitation, and impregnation. " The electrocatalytic activities were studied in both acidic and alkaline electrolytes. This chapter summarizes some of these recent results, which have provided us with further information for assessing gold-based alloy catalysts for fuel cell reactions. 

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