Showing papers on "Methanol published in 1984"

Catalase in vitro

Abstract: Publisher Summary Catalase exerts a dual function: (1) decomposition of H 2 O 2 to give H 2 O and O 2 (catalytic activity) and (2) oxidation of H donors, for example, methanol, ethanol, formic acid, phenols, with the consumption of 1 mol of peroxide (peroxide activity) The kinetics of catalase does not obey the normal pattern Measurements of enzyme activity at substrate saturation or determination of the K s is therefore impossible In contrast to reactions proceeding at substrate saturation, the enzymic decomposition of H 2 O 2 is a first-order reaction, the rate of which is always proportional to the peroxide concentration present Consequently, to avoid a rapid decrease in the initial rate of the reaction, the assay must be carried out with relatively low concentrations of H 2 O 2 (about 001 M) This chapter discusses the catalytic activity of catalase The method of choice for biological material, however, is ultraviolet (UV) spectrophotometry Titrimetric methods are suitable for comparative studies For large series of measurements, there are either simple screening tests, which give a quick indication of the approximative catalase activity, or automated methods

Partial oxidation of methane by nitrous oxide over molybdenum on silica

Abstract: Kinetic data are presented for the partial oxidation of methane to methanol and formaldehyde by nitrous oxide catalysed by molybdenum supported on silica when steam is present in the system. The data are used as evidence to show how the selective oxidation mechanism fits into an overall reaction scheme. Moreover, in support of this selective mechanism, spectroscopic evidence is given for the formation of methyl radicals and methoxide ions on the surface. 12 references, 7 figures, 1 table.

Hydrogen bonding in liquid methanol and ethanol determined by x‐ray diffraction

Abstract: The x‐ray diffraction patterns of liquid methanol and ethanol have been measured at 20 °C. The data are analyzed to yield the molecular structures, and the distinct structure functions Hd(k) are analyzed to obtain the hydrogen bonding in these alcohols. The data show clearly that hydrogen‐bonded hydroxyl groups occur in methanol and ethanol with an OH⋅⋅⋅OH distance of 2.8A, and that each hydroxyl group has 1.8±0.1 nearest neighbors at this distance.

Methanol Conversion to Light Olefins

Abstract: Light olefins will play a dominant role in any future methanol-based chemicals economy. Olefins are initial products in the conversion of methanol to hydrocarbons over zeolite catalysts [1]. The overall reaction path may be represented by

Cobalt catalysts for the conversion of methanol to hydrocarbons and for Fischer-Tropsch synthesis

Abstract: A rhenium promoted cobalt catalyst, especially a rhenium and thoria promoted cobalt catalyst, and process for the conversion of methanol to hydrocarbons. Methanol is contacted, preferably with added hydrogen, over said catalyst, or synthesis gas is contacted over said catalyst to produce, at reaction conditions, an admixture of C 10 + linear paraffins and olefins. These hydrocarbons can be further refined to high quality middle distillate fuels, and other valuable products such as mogas, diesel fuel, jet fuel, lubes and speciality solvents, particularly premium middle distillate fuels of carbon number ranging from about C 10 to about C 20 .

Influence of pH on Terminal Carbon Metabolism in Anoxic Sediments from a Mildly Acidic Lake.

Abstract: The carbon and electron flow pathways and the bacterial populations responsible for transformation of H2-CO2, formate, methanol, methylamine, acetate, glycine, ethanol, and lactate were examined in sediments collected from Knaack Lake, Wis. The sediments were 60% organic matter (pH 6.2) and did not display detectable sulfate-reducing activity, but they contained the following average concentration (in micromoles per liter of sediment) of metabolites and end products: sulfide, 10; methane, 1,540; CO2, 3,950; formate, 25; acetate, 157; ethanol, 174; and lactate, 138. Methane was produced predominately from acetate, and only 4% of the total CH4 was derived from CO2. Methanogenesis was limited by low environmental temperature and sulfide levels and more importantly by low pH. Increasing in vitro pH to neutral values enhanced total methane production rates and the percentage of CO2 transformed to methane but did not alter the amount of 14CO2 produced from [2-14C]acetate (∼24%). Analysis of both carbon transformation parameters with 14C-labeled tracers and bacterial trophic group enumerations indicated that methanogenesis from acetate and both heterolactic- and acetic acid-producing fermentations were important to the anaerobic digestion process.

Process for the preparation of ethanol from methanol, carbon monoxide _and hydrogen

Abstract: An integrated process for the preparation of ethanol from methanol, carbon monoxide and hydrogen feedstock is disclosed; the process featuring the steps of esterifying methanol and acetic acid to form methyl acetate; carbonylating the methyl acetate to form acetic anhydride; esterifying acetic anhydride with a lower aliphatic alcohol in an anhydrous zone to form the corresponding aliphatic acetate; hydrogenating the aliphatic acetate in a second anhydrous zone to form ethanol and the corresponding aliphatic alcohol; and separating the formed ethanol stream into an ethanol product stream and/or aliphatic alcohol recycle stream, which is recycled to react with acetic anhydride.

The interaction of methanol with Ru(001)

Abstract: The adsorption, desorption, and decomposition of methanol on a clean Ru(001) surface at 85 K has been examined with electron energy loss spectroscopy, multiple mass thermal desorption spectroscopy, low energy electron diffraction, and a work function probe. Methanol adsorbs readily on Ru(001) and is found to decompose at submonolayer coverages even at low temperature (85 K). Two decomposition pathways are observed: oxygen–hydrogen bond breaking (CH3OH→CH3O–M+H–M) and carbon–oxygen bond breaking (CH3OH→H2O+C–M+2H–M). The methoxy species either recombines with hydrogen and desorbs as methanol between 220 and 250 K via second order reaction kinetics (n=1.85; E*D≂14 kcal/mol; ν(2)=10−2 cm−2 s−1); or further decomposes to form carbon monoxide and hydrogen. The conversion of the methoxy species into carbon monoxide begins at 220 K and is completed at 300 K. The methoxy conversion is accompanied by the gradual formation of a p(2×2) LEED pattern which disappears after CO desorption. The second reaction channel, i.e., C–O bond breaking, results in the formation of water, which desorbs at 210 K, and in surface carbon, which was detected with oxygen titration. The results are discussed and compared to methanol decomposition on palladium and nickel and demonstrate the unique ability of Ruthenium for both C–O bond cleavage and formation of hydrogenatable methoxy species.

A flavonoid antioxidant in Spanish peanuts(Arachia hypogoea)

Abstract: Hot methanol extracts of Spanish peanuts were found to possess antioxidant activity. Thin layer (TLC) and paper chromatography of the methanolic peanut extracts yielded 6 fluorescent bands of which one exhibited potent antioxidant activity. Further separation by TLC showed this band to be a complex mixture of 3 components that were tested for antioxidant activity. One component demonstrated all of the antioxidant activity associated with the parent band. Analysis of this antioxidant by paper chromatography and TLC, chromatographic spray reagents and spectral analysis demonstrated that the compound was dihydroquercetin.

The chemical components of coffee.

Abstract: This chapter provides a list of the chemical components of coffee beans and beverages. The principal sources of aliphatic compounds in roasted coffee are fragmented carbohydrates and proteins. The aliphatic polyamines, putrescine, spermine, and spermidine, are present in green coffee beans, but they are all decomposed during the roasting process. Several of the lower molecular weight aliphatic compounds, in a mixture, are part of the roasted coffee aroma. A nine-compound mixture with roasted coffee aroma contained isopentane, n-hexane, acetaldehyde, dimethyl sulfide, propanal, isobutanal, isopentanal, methanol, and 2-methylfuran. Although the aromatic polycyclic hydrocarbons are usually associated with tar and soot formation, in a firing or roasting process, compounds such as fluoranthrene and pyrene have been found in green coffee. In coffee there is a series of phenolic compounds that is characteristically present, which are derived from caffeic and ferulic acids.

In vivo 13C NMR Investigations of Methanol Oxidation by the Obligate Methanotroph Methylosinus trichosporium OB3b

Abstract: SUMMARY: In vivo 13C NMR has been used to observe metabolism of exogenously supplied methanol by suspensions of Methylosinus trichosporium OB3b grown under a variety of conditions. Formaldehyde, formate and bicarbonate ions were the only metabolites of methanol to be detected. Accumulation of formaldehyde was observed only with suspensions grown under conditions which yield particulate, membrane-bound, methane mono-oxygenase (MMO). Ethyne abolished MMO activity, partially inhibited methanol oxidation in whole organisms, and prevented growth of the organism on methanol (1%, v/v) in batch culture. Oxidation of ethanol, a substrate of methanol dehydrogenase, was not affected by ethyne. Ethyne caused accumulation of formaldehyde in all suspensions of the organism incubated with methanol, although oxidation of exogenously added formaldehyde was not affected. These observations are consistent with the proposal that in M. trichosporium OB3b both MMO and methanol dehydrogenase oxidize exogenously supplied methanol and suggest that the further oxidation of formaldehyde is stimulated by the consumption of reducing equivalents by MMO.

Catalysis of an isotopic exchange between CO2 and the carboxyl group of acetate by Methanosarcina barkeri grown on acetate

Abstract: Cell suspensions of Methanosarcina barkeri (strain Fusaro) grown on acetate were found to catalyze the formation of methane and CO2 from acetate (30–40 nmol/min·mg protein) and an isotopic exchange between the carboxyl group of acetate and 14CO2 (30–40 nmol/min·mg protein). An isotopic exchange between [14C]-formate and acetate was not observed. Cells grown on methanol mediated neither methane formation from acetate nor the exchange reactions. The data indicate that the isotopic exchange between CO2 and the carboxyl group of acetate is a partial reaction of methanogenesis from acetate. Both reactions were completely inhibited by low concentrations of cyanide (20 μM) or of hydrogen (0.5% in the gas phase). Methane formation from acetate was also completely inhibited by low concentrations of carbon monoxide (0.2% in the gas phase) whereas only significantly higher concentrations of CO had an effect on the exchange reaction. In the concentration range tested KCN, H2 and CO had no effect on methane formation from methanol or from H2 and CO2; however, cyanide (20 μM) also affected methane formation from CO. The results are discussed with respect to proposed mechanisms of methane and CO2 formation from acetate.

Practical procedure for the chemoselective reduction of esters by sodium borohydride. Effect of the slow addition of methanol

Abstract: The effect of solvents on the reduction of esters was examined with readily available sodium borohydride which is known to be incapable of reducing such functional groups. In mixed solvents of t-butyl alcohol–methanol or tetrahydrofuran–methanol, various carboxylic esters and lactones were found to be reduced by sodium borohydride to the corresponding alcohols or diols in high yields. Slow addition of methanol to the refluxing mixture of ester and sodium borohydride in t-butyl alcohol or tetrahydrofuran was essential to achieve effective reduction. On the other hand, each individual solvent, methanol or t-butyl alcohol, was not effective for the reduction. The procedure provided a practical method for the functional group selective reduction of esters in the presence of chloro, cyano, carboxylato, carbamoyl, carboxy or nitro groups, which can not usually be performed by lithium aluminium hydride.

Production of fatty alcohols from fatty acids

Abstract: Detergent-range alcohols from natural feedstock can be produced by high pressure hydrogenation of either methyl esters or fatty acids. The increasing quantities of fats and oils on the world market secure a reliable and economically priced material. Although fatty acid is an abundant worldwide commodity, most alcohol producers hydrogenate methyl esters, because direct hydrogenation of fatty acids is difficult as the catalyst is sensitive to acid attack. The process described here makes it possible to hydrogenate fatty acids directly to alcohols of high quality without prior esterification. The reaction takes place in the liquid phase over a fine-grained copper chromite slurry in a single reactor vessel. A special reactor design with an optimum arragement of the feeding nozzles causing an appropriate circulation of the reacting components inside the reactor facilitates the rapid “in situ” esterification reaction. This minimizes the free fatty acid concentration in the reactor to nearly zero. This results in a low consumption of catalyst. The most important advantages of the process are: direct feed of fatty acids of various origins, use of reasonably priced raw materials such as soapstock fatty acids and lower grade tallow acids, no process steps with methanol, and excellent economics. The process is industrially proven.

Infrared spectroscopy of copper/zinc oxide catalysts for the water-gas shift reaction and methanol synthesis

Abstract: A bidentate formate species adsorbed on a zinc site was a common intermediate in the water-gas shift and methanol synthesis reactions on Cu/ZnO catalysts. Adsorbed formaldehyde and methoxy species were identified as additional intermediates in the reaction pathway for methanol synthesis. An adsorbed carbonyl species on a reduced copper site was an activating agent for the reduction of formate groups to formaldehyde and methoxy species at 200/sup 0/C. 37 references, 6 figures, 1 table.