Showing papers on "Methanol published in 1978"

Photoelectrochemical reduction of aqueous carbon dioxide on p-type gallium phosphide in liquid junction solar cells

Abstract: THE non-biological reduction of carbon dioxide to organic compounds is of interest, as an alternative to natural photosynthesis, for the production of organic raw materials or fuel. In one approach, the required energy was supplied by irradiation with UV light, in the presence of ferrous salts, and resulted in the production of formic acid and of formaldehyde1. In another approach, the energy was supplied from an external power source by electrochemical reduction of aqueous carbon dioxide. The reduction of carbon dioxide and production of formic acid during the electrolysis of sodium bicarbonate in aqueous solutions has also been reported2, and a study of the reduction of carbon dioxide on a mercury cathode reviews earlier work3. Polarographic measurements on mercury electrodes showed that carbon dioxide, rather than the bicarbonate ion, is the electroactive species, with a half-wave reduction potential of −2.1 V (relative to SCE), and that formic acid is the only product4. We report here the photoassisted electrolytic reduction of aqueous carbon dioxide, achieved using p-type gallium phosphide as a photocathode, with part or all of the energy being supplied by light. The products were formic acid, formaldehyde and methanol.

Growth and Methanogenesis by Methanosarcina Strain 227 on Acetate and Methanol

Abstract: Methanosarcina strain 227 exhibited exponential growth on sodium acetate in the absence of added H2. Under these conditions, rates of methanogenesis were limited by concentrations of acetate below 0.05 M. One mole of methane was formed per mole of acetate consumed. Additional evidence from radioactive labeling studies indicated that sufficient energy for growth was obtained by the decarboxylation of acetate. Diauxic growth and sequential methanogenesis from methanol followed by acetate occurred in the presence of mixtures of methanol and acetate. Detailed studies showed that methanol-grown cells did not metabolize acetate in the presence of methanol, although acetate-grown cells did metabolize methanol and acetate simultaneously before shifting to methanol. Acetate catabolism appeared to be regulated in response to the presence of better metabolizable substrates such as methanol or H2-CO2 by a mechanism resembling catabolite repression. Inhibition of methanogenesis from acetate by 2-bromoethanesulfonate, an analog of coenzyme M, was reversed by addition of coenzyme M. Labeling studies also showed that methanol may lie on the acetate pathway. These results suggested that methanogenesis from acetate, methanol, and H2-CO2 may have some steps in common, as originally proposed by Barker. Studies with various inhibitors, together with molar growth yield data, suggest a role for electron transport mechanisms in energy metabolism during methanogenesis from methanol, acetate, and H2-CO2.

Selective formation of methanol from synthesis gas over palladium catalysts

Abstract: It is reported that hydrogenation of CO over supported Pd catalysts produces methanol in high selectivity within the temperature-pressure regime where CH/sub 3/OH formation is thermodynamically allowed. The same behavior was found for Pt and Ir as well, but at lower rates. The mechanism of CH/sub 3/OH formation on Pd is discussed. 3 tables, 33 references. (DLC)

Catalysis by Supported Metal Crystallites from Carbonyl Clusters. I. Catalytic Methanol Synthesis under Mild Conditions over Supported Rhodium, Platinum, and Iridium Crystallites Prepared from Rh, Pt, and Ir Carbonyl Cluster Compounds Deposited on ZnO and MgO

Abstract: Methanol synthesis by the catalytic hydrogenation of carbon monoxide proceeded under atmospheric pressure and at 150–250 °C over rhodium, platinum and iridium crystallite catalysts, prepared from well-defined Rh, Pt, and Ir carbonyl cluster compounds highly dispersed on ZnO and MgO. The activity and selectivity of methanol formation depended considerably on the kind of metal carbonyl clusters and metal oxides employed as inorganic carriers. The catalysts prepared by the pyrolysis of smaller Rh, Pt, and Ir carbonyl clusters on ZnO, MgO, CaO, and BeO exhibited a higher selectivity of methanol synthesis. A small amount of ethanol was also produced besides methanol in CO–H2 reaction over the pyrolysed catalysts of Rh carbonyl clusters on MgO, CaO, and BeO. Other metal oxides such as SiO2 gel, γ-Al2O3, SnO2, and WO2 were employed for preparation of the dispersed Rh catalysts from carbonyl clusters, which catalysed mainly formation of methane and higher hydrocarbons with negligible selectivity of the oxygenated...

Influence of the fire retardant ammonium polyphosphate on the thermal degradation of poly(methyl methacrylate)

Abstract: The thermal degradation of ammonium polyphosphate (APP), a commercial fire retardant, and its blends with poly(methyl methacrylate) (PMMA) have been studied by thermal volatilization analysis (TVA) and the degradation products identified. APP degrades under vacuum in three stages. Initially it condenses to an ultraphosphate ( 370°C). In the presence of APP, the normal depolymerization of PMMA to monomer competes with degradation reactions which form high-boiling chain fragments, methanol, carbon monoxide, dimethyl-ether, carbon dioxide, hydrocarbons, and char. These additional reactions are initiated principally by the PPA. Intramolecular cyclization occurs, resulting in the formation of anhydride, and ester groups are eliminated, methanol and carbon monoxide being evolved. Further degradation of the modified polymer leads to the other volatile products and the char.

Process for the preparation of dialkyl carbonates

Abstract: A process is described for the preparation of dialkyl carbonates by oxidative carbonylation of the corresponding alcohol in the presence of a copper-containing catalyst at elevated temperature and elevated pressure, which process permits simple separation of the copper-containing catalyst by sedimentation, and of the reaction water in the case of methanol by simple distillation from the reaction solution.

One carbon metabolism in methanogenic bacteria

Abstract: Two strains of Methanosarcina (M. Barkeri strain MS, isolated from sewage sludge, and strain UBS, isolated from lake sediments) were found to have similar cellular properties and to have DNA base compositions of 44 mol percent guanosine plus cytosine. Strain MS was selected for further studies of its one-carbon metabolism. M. barkeri grew autotrophically via H2 oxidation/CO2 reduction. The optimum temperature for growth and methanogenesis was 37°C. H2 oxidation proceeded via an F420-dependent NADP+-linked hydrogenase. A maximum specific activity of hydrogenase in cell-free extracts, using methyl viologen as electron acceptor, was 6.0 μmol min · mg protein at 37°C and the optimum pH (9.0). M. barkeri also fermented methanol andmethylamine as sole energy sources for growth. Cell yields during growth on H2/CO2 and on methanol were 6.4 and 7.2 mg cell dry weight per mmol CH4 formed, respectively. During mixotrophic growth on H2/CO2 plus methanol, most methane was derived from methanol rather than from CO2. Similar activities of hydrogenase were observed in cell-free extracts from H2/CO2-grown and methanol-grown cells. Methanol oxidation apparently proceeded via carrierbound intermediates, as no methylotrophy-type of methanol dehydrogenase activity was observed in cell-free extracts. During growth on methanol/CO2, up to 48% of the cell carbon was derived from methanol indicating that equivalent amounts of cell carbon were derived from CO2 and from an organic intermediate more reduced than CO2. Cell-free extracts lacked activity for key cell carbon synthesis enzymes of the Calvin cycle, serine path, or hexulose path.

Catalysis by Supported Metal Crystallites from Carbonyl Clusters. II. Catalytic Ethanol Synthesis from CO and H2 under Atmospheric Pressure over Supported Rhodium Crystallites Prepared from Rh Carbonyl Clusters Deposited on TiO2, ZrO2, and La2O3

Abstract: Ethanol was catalytically produced in the CO–H2 reaction under atmospheric pressure and at 150–250 °C over rhodium crystallite catalysts prepared from Rh carbonyl cluster compounds highly dispersed on La2O3, TiO2, and ZrO2. The activity and selectivity of ethanol formation depend on the kind of metal carbonyl cluster and metal oxide used as inorganic carriers. The catalysts prepared by the pyrolysis of smaller Rh carbonyl clusters such as Rh2(C5H5)2(CO)3, Rh4(CO)12, and Rh6(CO)16 on La2O3, TiO2, and ZrO2 show higher selectivity of the oxygenated products containing ethanol (main), acetaldehyde, and methanol. The ethanol contents in the oxygenated products increased considerably above 200 °C over the catalysts. CeO2 and ThO2 were also employed in the preparation of the pyrolysed catalysts to disperse the Rh carbonyl clusters, which catalyses the ethanol formation in the CO–H2 reaction at atmospheric pressure.

Preparation of Colloidal Rhodium in Poly(vinyl Alcohol) by Reduction with Methanol

Abstract: Refluxing of a solution of poly(vinyl alcohol) and rhodium(III) chloride in methanol-water gives a colloidal dispersion of rhodium which is an effective catalyst for hydrogenation of cyclohexene in methanol at 30°C under atmospheric hydrogen pressure. Formaldehyde is produced quantitatively with the reduction of rhodium(III) chloride to metallic rhodium. The rhodium particles in the colloidal dispersion are found to consist of two kinds of particles, about 8 and 40 A in diameter by electron microscopy. The sizes of the small (8 A) and large (40 A) particles are almost constant during the course of refluxing. The number of small particles, which is the great majority of particles at the early stage of refluxing, gradually decreases; concurrently the number of large particle increases on prolonged refluxing. An absorption peak appears at 260 nm at the early stage of refluxing. The presence of the 260 nm peak, which indicates the coordination of poly(vinyl alcohol) to rhodium(III) ion, is indispensa...

Acetate metabolism in Methanosarcina barkeri.

Abstract: Methanosarcina barkeri was grown by acetate fermentation in complex medium (N2 gas phase). The molar growth yield was 1.6–1.9 g cells/mol methane formed. Under these conditions 63–82% of the methane produced byMethanosarcina strains was derived from the methyl carbon of acetate, indicating that some methane was derived from other media components. Growth was not demonstrated in complex media lacking acetate or mineral acetate medium containing acetate but lacking H2/CO2, methanol, or trypticase and yeast extract. Acetate metabolism byM. barkeri strain MS was further exmined in mineral acetate medium containing H2/CO2 and/or methanol, but lacking cysteine. Under these conditions, more methane was derived from the methyl carbon of acetate than from the carboxyl carbon. Methanogenesis from the methyl group increased with increasing acetate concentration. The methyl carbon contributed up to 42% of the methane formed with H2/CO2 and up to 5% with methanol. Methanol stimulated the oxidation of the methyl group of acetate to CO2. The average rates of methane formation from acetate were 1.3 nomol/min ·ml/culture (0.04mg2 cell dry weight) in defined media (gas phase H2/CO2) and complex media (gas phase N2). Acetate contributed up to 60% of cell carbon formed under the growth conditions examined. Similar quantities of cell carbon were derived from the methyl and carboxyl carbons of acetate, suggesting incorporation of this compound as a two-carbon unit. Incorporated acetate was not preferentially localized in lipid material, as 70% of the incorporated acetate was found in the wall and protein cell fractions. Acetate catabolism was stimulated by pregrowing of cultures in media containing acetate, while acetate anabolism was not influenced. The results are discussed in terms of the differences between the mechanisms of acetate catabolism and anabolism.

Effects of hydrogen bonding on the Raman intensities of methanol, ethanol and water

Abstract: The absolute Raman intensities of methanol, ethanol and water in the gas and liquid phases have been measured using 514.5 and 337.1 nm excitation. Large intensity changes were observed for the Raman lines of the OH stretching vibrations in changing from gas to liquid. The observed intensity changes are interpreted as due to the additional contribution of the charge transfer electronic excited state arising from hydrogen bond formation. The Raman intensities of methanol, ethanol and water in alkali halide solutions were also studied. The observed effects of halide ions on the intensities and their excitation wavelength dependences were found to be well correlated with the known charge transfer states resulting from electron transfer from the halide ion to the surrounding solvent molecules.

Interaction of alcohols with proteins

Abstract: The kinetics of denaturation of egg albumin have been determined for methanol, ethanol, propanol, and butanol. The reactions are first order in respect to protein but between 11th and 18th order for the alcohols. The denaturation reaction is characterized by a large temperature coefficient with little or no dependence on pH. There is a marked change of pH when proteins are denatured. A series of eight proteins has been studied. There is surprisingly little difference in susceptibility to alcohol denaturation between the various proteins. Methanol, ethanol, propanol, and butanol are strongly bound to egg albumin—butanol being the most strongly bound. The binding of alcohol is probably accompanied by protein dehydration. The polyhydric alcohols' behavior is much different. These alcohols do not denature proteins and the protein is hydrated. Sucrose produces the greatest degree of hydration.

Electron-transport chain and coupled oxidative phosphorylation in methanol-grown Paracoccus denitrificans.

Abstract: Methanol dehydrogenase of Paracoccus denitrificans was shown to be very similar to the enzyme of Pseudomonas sp, M. 27. The Km value for methanol with excess activator (ammonium ions) is 35 μM. The pH optimum for enzyme activity with 2,6-dichlorophe-nolindophenol as electronacceptor was at 9.0 A CO-binding type of cytochrome c was present only in cells grown with methanol as carbon and energy source.

Derepression and partial insensitivity to carbon catabolite repression of the methanol dissimilating enzymes in Hansenula polymorpha.

Abstract: The regulation of the synthesis of alcohol oxidase, catalase, formaldehyde dehydrogenase, and formate dehydrogenase was investigated in the methanol-utilizing yeastHansenula polymorpha during growth on different carbon and energy sources. When cells were grown on glucose, the enzymes of the dissimilatory methanol metabolism were not detected during the exponential phase of growth, but were formed in the late stationary phase without addition of methanol. Moreover, the enzymes were synthesized during growth on sorbitol, glycerol, ribose, and xylose. It was shown that the carbon catabolite insensitivity of the synthesis of methanol-specific enzymes is not limited to substrates that are slowly metabolized.

The Prediction of Growth Yields in Methylotrophs

Abstract: Equations have been developed for assimilation of methane, methanol, methylamine, dimethylamine, trimethylamine, formaldehyde and formate into cell material by bacteria using the ribulose monophosphate pathway, the ribulose bisphosphate pathway and the serine pathway of carbon assimilation. The equations have been used for predicting the effect on cell yields (Y s, Y o2 and Y co2) of various P/O ratios, systems for substrate oxidation and assimilation pathways. The generalizations relating P/O ratios and cell yields, which have been used previously for such calculations, are not always applicable to methylotrophs. In particular, for the majority of methylotrophs the growth yield is determined by NAD(P)H supply as well as ATP supply, and for some methylotrophs growth yields may be exclusively NAD(P)H-limited. Because of this NAD(P)H limitation, the concept of Y ATP in methylotrophs should be used with extreme caution.

Colloidal rhodium in poly(vinylpyrrolidone) as hydrogenation catalyst for internal olefins

Abstract: Refluxing of a methanol solution of rhodium(III) chloride and poly(vinylpyrrolidone) with sodium hydroxide gives a stable colloidal dispersion of rhodium particles of 8.8 A in diameter. The colloidal dispersion exhibits a high catalytic activity for hydrogenation of internal olefins at 30°C under an atmospheric hydrogen pressure.

Cellular fatty acid composition in methanol-utilizing bacteria

Abstract: Composition of cellular fatty acids in methanol-utilizing bacteria was examined from the viewpoint of taxonomy. This group of bacteria showed a rather simple composition of cellular fatty acids, and was divided into two major groups on the basis of this composition. Pseudomonas methylotropha NCIB 10510, 10511, 10512, 10513, and 10515 showed the presence of a large amount of straight-chain saturated and unsaturated acids of C16:0 and C16:1, a small amount of straight-chain 3-hydroxy acid of C10:0, and a minor amount of other acids. Other methanol-utilizing bacteria, Pseudomonas extorquens NCIB 9399, Pseudomonas spp. NCIB 9133, 9686, and 10597, and Protaminobacter rubes NCIB 2879, showed the presence of a large amount of straight-chain unsaturated acid of C18:1, and a minor amount of other acids. Almost identical fatty acid composition was obtained from Microcyclus polymorphum NCIB 10516 and Hyphomicrobium variabile NCIB 10517, with the exception of the presence of cyclopropane acid of C19:0 and other unknown acids. It was noteworthy that almost identical fatty acid composition was found in the cells grown on methanol-containing media and in the cells grown on media not containing methanol, in the both groups of methanol-utilizing bacteria.

Stratospheric positive ion chemistry of formaldehyde and methanol

Abstract: The reactions of H3O+·nH2O ions with CH2O and CH3OH have been studied in flowing afterglow and flow drift reaction systems. Hydrated protonated formaldehyde, CH2OH+·nH2O, reacts with H2O to form H3O+ hydrates and CH2O for small n. Therefore protonated formaldehyde ions are not expected to have significant atmospheric concentrations. Methanol reacts rapidly with H3O+ ·nH2O ions for n = 0, 1, 2, and 3. The absence of protonated methanol ions in the atmosphere above 40 km, where H3O+ ·nH2O (n = 0, 1, 2, and 3) are observed to be the dominant ions, yields a useful upper limit on the atmospheric concentration of methanol.