Mol Of Methanol Research Articles

Single-step selective oxidation of methane to methanol in the aqueous phase on iridium-based catalysts

In this work, one-step conversion of methane to methanol using molecular oxygen as the oxidant in the presence of CO in aqueous solutions on copper or palladium promoted Ir-ZSM-5 catalyst is first reported. The addition of a second metal to Ir-ZSM-5 promotes the catalyst activity, while product selectivity can be tuned either to methanol on IrCu-ZSM-5 or to formic acid exclusively on IrPd-ZSM-5. Most effective is the combination of the three metal species together. Approximately 1200 μmol/gcat methanol, or ∼23.4 mol of methanol per mol of Ir, are formed on the IrCuPd trimetallic system (methanol selectivity ∼80 %) at 150 °C in 1 h. Our results also demonstrate that atomically dispersed Ir(I)(CO)2 species formed in the presence of CO can activate the C–H bond of methane to methyl species at temperatures below 150 °C. The good stability in cyclic operation is an additional attribute, rendering this type of catalyst a “front-runner” in future catalyst development for direct methane-to-liquid oxygenates.

Methanol-Acetonitrile Separation By Extractive Distillation Using ILs

Present paper includes the usage of Ionic Liquids as greener solvents in extractive distillation by substituting conventional solvents. For the separation of minimum boiling methanol-acetonitrile azeotropic system, extractive distillation was carried out in Aspen HYSYS process simulator by using ionic liquids as solvent. Three imidazolium based ionic liquids namely 1-butyl-3-methylimidazolim acetate ([BMIM][OAc]), 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), 1-butyl-3-methylimidazolium bromide ([BMIM][Br]) used, were added as hypothetical compound in Aspen HYSYS. Flowsheet was simulated using NRTL as the thermodynamic model, giving a purity of 99.9% by mol of methanol in distillate. Optimization of distillation process was done by varying flow rate of ionic liquid, column stages, feed stage location, ionic liquid stage location and reflux ratio. A Total Cost Analysis (TAC) was carried out by using Economic Analyzer in Aspen HYSYS to compare the optimized design. [BMIM][OAc] is found to most suitable according to the energy and cost analysis.

Thermodynamic Modeling of the Stage of Polychlorinated Biphenyls Preparation to Thermal Decomposition

The reaction of Sovol (technical mixture of polychlorinated biphenyls) with sodium methoxide in dimethyl sulfoxide and methanol has been studied using the thermodynamic modeling method. The optimal process conditions have been elaborated: 1 atm, 115°C, 0.25 mol of dimethyl sulfoxide, 0.085 mol of methanol, the polychlorinated biphenyls: sodium methoxide molar ratio = 1: 4. Experimental data on the interaction of the polychlorinated biphenyls with sodium methoxide under the theoretically determined conditions have revealed a range of positive effects: savings of the reactants, complete conversion, and the formation of potentially less toxic compounds. The studied interaction can serve as a stage for the pretreatment of toxic polychlorinated biphenyls for the pyrolytic destruction.

Tuning the Adsorption Energy of Methanol Molecules Along Ni‐N‐Doped Carbon Phase Boundaries by the Mott–Schottky Effect for Gas‐Phase Methanol Dehydrogenation

AbstractEngineering the adsorption of molecules on active sites is an integral and challenging part for the design of highly efficient transition‐metal‐based catalysts for methanol dehydrogenation. A Mott–Schottky catalyst composed of Ni nanoparticles and tailorable nitrogen‐doped carbon‐foam (Ni/NCF) and thus tunable adsorption energy is presented for highly efficient and selective dehydrogenation of gas‐phase methanol to hydrogen and CO even under relatively high weight hourly space velocities (WHSV). Both theoretical and experimental results reveal the key role of the rectifying contact at the Ni/NCF boundaries in tailoring the electron density of Ni species and enhancing the absorption energies of methanol molecules, which leads to a remarkably high turnover frequency (TOF) value (356 mol methanol mol−1 Ni h−1 at 350 °C), outpacing previously reported bench‐marked transition‐metal catalysts 10‐fold.

The effect of phase transition of methanol on the reaction rate in the alkylation of hydroquinone

An O-alkylation reaction of hydroquinone with excess methanol was carried out by using alkaline metal ion-exchanged zeolite catalysts at various phases of methanol in a slurry type reactor. The amount of methanol, used as a methylating agent and also a solvent, significantly affected the reaction rate. When the amount of methanol was decreased from 2 mol to 0.6 mol, the reaction rate was increased more than nine times. These changes in the reaction rate could be explained by the pressure change and the phase transition of the reactant, methanol, depending on the temperature and the elimination of a diffusion limitation of reactants through the zeolite pores in a gas phase condition. Thus, higher than 89% selectivity to 4-methoxyphenol was obtained at 80% conversion of hydroquinone at a gas phase reaction condition using 1 mol of methanol for 2 hours.

Transient behaviour of a small methanol reformer for fuel cell during hydrogen production after cold start

Abstract The cold start transient characteristics of a small methanol reformer for a fuel cell were investigated. The main parameters studied were the oxygen to methanol mol ratio (O/C), fuel supply rate, heating power and heating temperature. The composition of the gas produced by the reformer was analysed. The main aim of this paper was to determine a favorable combination of the parameters for obtaining rapid hydrogen production during the transient behaviour of the reformer. A small methanol reformer with fuel, air and water injectors, heaters and a catalyst was constructed. Vaporised methanol was injected into the reformer, which then flowed into the catalyst. For the purpose of enhancing the response of the cold start transient reaction, eight glow plugs were mounted at the inlet of the catalyst to control the flow temperature together with the adjustment of the oxygen to methanol mol ratio. The best response from cold start was obtained with 960 W heating power, 80 °C heating temperature, 14 mL/min methanol and 70 L/min air supply rates among the experimented parameters. Under this operation setting, hydrogen was produced after 220 s from cold start with the production rate stabilising after 4–5 min and eventually reaching the highest concentration at 350 °C. Generally, hydrogen commenced production at a catalyst outlet temperature of 100 °C and stabilised at 350 °C.

Structural Study and Solution Integrity of Dioxomolybdenum(VI) Complexes with Tridentate Schiff Base and Azole Ligands

Four new molybdenum complexes [MoVIO2(L1)(Him)] (1), [MoVIO2(L1)(3-MepzH] (2), [MoVIO2(L2)(3-MepzH)] (3), and [(MoVIO2)2(μ-L3)(MeOH)2] (4) were synthesized and characterized by IR, NMR, ESI-MS, and single-crystal structure analysis [H2L1 = 2-(salicylideneamino)-2-methyl-1-propanol, H2L2 = 2-(3-methoxysalicylideneamino)-2-methyl-1-propanol, H4L3 = 1, 7-bis(salicylidene)dihydrazide malonic acid, Him = imidazole and 3-MepzH = 3-methylpyrazole]. In all four structures the molybdenum atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base di- or tetraanion (L1, 2)2—/(L3)4— and one oxo group occupying the sites of the equatorial plane. The other oxo group and the azole or methanol molecule occupy the apical sites. In 1—3 two centrosymmetrically related molecules form a hydrogen-bonded pair through the (azole)N-H···O(alkoxo) interaction. Additional crystal packing appears to be controlled mostly by π stacking between the aromatic rings of the salicyl moiety. ESI-MS investigations reveal that the integrity of complexes 1—4 is largely retained in methanol solution. At the same time evidence is provided that di- to tetranuclear oligomers of formula [{MoVIO2(L)}x] and [{MoVIO2(L)}x(3-MepzH)] with L = L1, L2, x = 2, 3, 4 are present simultaneously with 2 and 3 in methanol solution, respectively the tetranuclear species [{(MoVIO2)2(L3)}2] with 4. Strukturuntersuchungen und molekulare Assoziation in Lösung von Dioxomolybdän(VI)-Komplexen mit dreizähnigen Schiff-Basen und Azol-Liganden Vier neue Molybdänkomplexe [MoVIO2(L1)(Him)] (1), [MoVIO2(L1)(3-MepzH] (2), [MoVIO2(L2)(3-MepzH)] (3) und [(MoVIO2)2(μ-L3)(MeOH)2] (4) wurden hergestellt und mit IR, NMR, ESI-MS und Einkristall-Röntgenstrukturanalyse charakterisiert [H2L1 = 2-(Salicylideneamino)-2-methyl-1-propanol, H2L2 = 2-(3-Methoxysalicylideneamino)-2-methyl-1-propanol, H4L3 = 1, 7-Bis(salicylidene)dihydrazidmalonsäure, Him = Imidazol und 3-MepzH = 3-Methylpyrazol]. In allen vier Strukturen weist das Molybdänatom eine verzerrt-oktaedrische Koordination auf, mit den drei meridionalen Donoratomen des Di- oder Tetraanions (L1, 2)2—/(L3)4— der Schiff-Base und einer Oxo-Gruppe in der equatorialen Ebene. Die zweite Oxo-Gruppe und das Azol- oder Methanolmolekül besetzen die apikalen Stellen. In 1—3 sind immer zwei zentrosymmetrisch zueinander in Beziehung stehende Moleküle über (azol)N-H···O(alkoxo) Wasserstoffbrücken paarweise miteinander verknüpft. Die weitere Kristallpackung scheint hauptsächlich durch π-Stapelung zwischen den aromatischen Ringen des Salicylrestes kontrolliert zu werden. ESI-MS Untersuchungen zeigen, dass die Zusammensetzung der Komplexe 1—4 in methanolischer Lösung im wesentlichen beibehalten wird. Gleichzeitig gibt es Hinweise, dass di- bis tetranukleare Oligomere der Formeln [{MoVIO2(L)}x] and [{MoVIO2(L)}x(3-MepzH)] mit L = L1, L2, x = 2, 3, 4 neben 2 und 3 in methanolischer Lösung vorliegen, bzw. die tetranukleare Spezies [{(MoVIO2)2(L3)}2] von 4.

Microfuel processor for use in a miniature power supply

A microscale fuel reformer for use with a miniature fuel cell has been built and operated at efficiencies that make them attractive for use as a miniature power supply for microelectronics. The fuel reformer and the results of initial tests are discussed. The fuel processor assembly consists of two vaporizer/preheaters, a heat exchanger, a combustor, and a steam reformer. Methanol was identified as a good candidate for use in the microscale reformer. A proprietary catalyst was developed to reform methanol. The catalyst was able to process a methanol water mixture (1:1 by weight) into a hydrogen-rich stream composed of 73–74 vol% H 2, 25–26 vol% CO 2, and 0.6–1.2 vol% CO on a dry basis. Almost 3 mols of hydrogen per mol of methanol reacted, which approached the theoretical maximum. An integrated fuel processor that used proprietary catalyst in the reformer and catalytic combustion to provide the heat was designed and built. The reformer and combustor were each less than 5 mm 3 in volume. When 100 mW e of hydrogen was produced, a thermal efficiency of 9%, or an estimated 4.5% net efficiency (including a hypothetical fuel cell), was achieved.

Equilibrium and diffusion of methanol and water in a nafion 117 membrane

AbstractThe uptake concentrations of methanol and water in a Nafion membrane are measured as a function of methanol mol fraction from a liquid methanol–water mixture. The results are fitted by a thermodynamically consistent equation, derived from an expression of the Gibbs energy. The uptake of pure methanol and pure water from the vapor phase is measured as a function of vapor pressure. A discontinuity, known in the literature as Schroeder's paradox, between membrane uptakes of pure methanol and pure water from the liquid and vapor phases is noted. Regions of unconditional instability are enveloped by spinodal loci for the ternary mixture in the membrane when equilibrated with liquid mixtures. The effective diffusion coefficient is measured at 60°C for diffusion from a vapor into a saturated Nafion membrane. The effective diffusion coefficients are found to be on the order of 10−11 m2/s, which is comparable to other measurements made for diffusion of a vapor through the membrane.

Growth on methanol and conversion of methoxylated aromatic substrates by Desulfotomaculum orientis in the presence and absence of sulfate

A three-membered microbial community that completely metabolizes syringic acid to methane and carbon dioxide was originally enriched from anoxic sediment of the lake Zürich. From this enrichment a sulfate- reducing, demethylating, spore-forming organism, classified as Desulfotomaculum orientis, was isolated. It cleaves the phenylether bonds of methyxylated aromatic compounds, producing the corresponding hydroxylated derivatives. The organism ferments the carbon of methoxy-groups as well as methanol to acetate using carbon dioxide as electron acceptor. In the presence of sulfate, methoxy carbon and methanol are completely oxidized to CO 2 coupled to the formation of hydrogen sulfide. Growth yields under fermenting conditions are 4.0 to 6.4 g of dry cell mass per mol of methanol or methoxy-carbon consumed. Under sulfate reducing conditions the corresponding values are 4.8 to 8.2 g for methanol and methoxy-carbon. The acetyl-CoA pathway is proposed as the main metabolic route for assimilation and dissimilation of these C 1-substrates. Acetate added to the culture medium cannot be utilized and it is not needed to promote growth in solely C-1 substrate containing media neither under sulfate-reducing nor under fermenting conditions. The ability of Desulfotomaculum orientis to endure unfavorable environmental conditions through sporulation, its versatility with regard to substrate utilization and its metabolic flexibility make it well adapted to be a member of transient anoxic fresh water sediment communities.

Methanol and methylamine utilization result from mutational events in Thiosphaera pantotropha

With choline as carbon source Thiosphaera pantotropha GB17 grew with a doubling time (td) of 6 h. The cellular yield was 55.8 g dry cell weight per mol of choline, indicating that its methyl moieties were used for growth. However, T. pantotropha was unable to grow with methanol or with methylamine as carbon source. Mutants were isolated from liquid or from solid media able to grow with methanol (Mox+) as carbon or methylamine as nitrogen source (Mam+). The Mox+ mutant GB17M grew with a mean td of 11.7h and a growth yield of 8.9 g dry cell weight per mol of methanol. Diauxic growth of strain GB17M was observed with mixtures of pyruvate and methanol as substrates in batch culture. Methanol led to the formation of methanol dehydrogenase, formate dehydrogenase, ribulosebisphosphate carboxylase and of a soluble cytochrome c-551.5. Tn5-insertional mutants defective in the thiosulfate oxidizing enzyme system or in hydrogenase acquired the Mox+ phenotype. However, Tn5-insertional mutants defective in either a c-type cytochrome or the molybdenum cofactor did not mutate to the Mox+ phenotype, indicating common functions in thiosulfate and in methanol metabolism.

Comparison of lignin peroxidase, horseradish peroxidase and laccase in the oxidation of methoxybenzenes

Lignin peroxidase oxidizes non-phenolic substrates by one electron to give aryl-cation-radical intermediates, which react further to give a variety of products. The present study investigated the possibility that other peroxidative and oxidative enzymes known to catalyse one-electron oxidations may also oxidize non-phenolics to cation-radical intermediates and that this ability is related to the redox potential of the substrate. Lignin peroxidase from the fungus Phanerochaete chrysosporium, horseradish peroxidase (HRP) and laccase from the fungus Trametes versicolor were chosen for investigation with methoxybenzenes as a homologous series of substrates. The twelve methoxybenzene congeners have known half-wave potentials that differ by as much as approximately 1 V. Lignin peroxidase oxidized the ten with the lowest half-wave potentials, whereas HRP oxidized the four lowest and laccase oxidized only 1,2,4,5-tetramethoxybenzene, the lowest. E.s.r. spectroscopy showed that this congener is oxidized to its cation radical by all three enzymes. Oxidation in each case gave the same products: 2,5-dimethoxy-p-benzoquinone and 4,5-dimethoxy-o-benzoquinone, in a 4:1 ratio, plus 2 mol of methanol for each 1 mol of substrate. Using HRP-catalysed oxidation, we showed that the quinone oxygen atoms are derived from water. We conclude that the three enzymes affect their substrates similarly, and that whether an aromatic compound is a substrate depends in large part on its redox potential. Furthermore, oxidized lignin peroxidase is clearly a stronger oxidant than oxidized HRP or laccase. Determination of the enzyme kinetic parameters for the methoxybenzene oxidations demonstrated further differences among the enzymes.

Rotational relaxation of azobenzene in porous Vycor glass

Polarised picosecond transient grating experiments on azobenzene molecules doping a solution of 4.3 mol of methanol in toluene demonstrate that rotational relaxation is much faster in the bulk fluid than in the fluid embedded in Corning 7930 Vycor glass. As rotational and translational Brownian motions are related to each other, this proves a drastic change in the diffusion coefficients even on a microscopic length scale, which is in contradiction with a previously suggested fractal model. The authors interpret this feature in terms of sticking effects on porous walls. Since macroscopic and microscopic diffusion coefficients can be determined using the same transient grating experiment by looking at the long- and the short-time-scale behaviours, respectively, it is suggested these two techniques are used simultaneously in order to investigate the influence of pore tortuosity and connectivity on the diffusion properties.

Radiolysis of Methanol Adsorbed on Zeolite

Abstract Radiolysis of methanol adsorbed on synthesized zeolite was investigated by means of product analysis. Molecular hydrogen, formaldehyde, and ethylene glycol are produced as major products. The G-value for the formation of H2 increases with increasing amount of methanol adsorbed on zeolite and approaches ca. 2.1 at about 10−2 mol of methanol per g of zeolite, where the coverage of methanol is approximately unity and G-values of ca. 1.0 are observed for formaldehyde and ethylene glycol. Addition of an electron scavenger causes decrease in G(H2). However, the hydrogen formation is not completely suppressed by N2O, SF6, or CCl4. Kinetics in solution is useful for the interpretation of results and allows the estimation of the G-value for the generation of electron in zeolite and of its relative reactivity toward methanol and some electron scavengers.

Utilization of Methanol plus Hydrogen by Methanosarcina barkeri for Methanogenesis and Growth

Methanosarcina barkeri grew on methanol plus H(2). Both substrates were consumed in equimolar amounts. Growth was strictly dependent on the presence of acetate, which was required for the biosynthesis of cellular constituents. Only about 0.4% of the methane produced originated from acetate. By using deuterated methanol, it was demonstrated that methanogenesis from this compound under H(2) did not occur via oxidation of methanol to CO(2) and subsequent reduction but by direct reduction with H(2). Growth yields with methanol plus H(2) and with methanol alone were not significantly different: 2.8 g of cells per mol of methanol in mineral medium and 4.6 g of cells per mol of methanol in complex medium, respectively. Growth of M. barkeri on methanol plus H(2) depended strictly on the presence of sodium ions in the medium. In the presence of 50 mM K the K(s) for Na was 5 mM.

Fixation of molecular nitrogen byMethanosarcina barkeri

Methanosarcina barkeri cells were observed in ammonia-free anaerobic acetate enrichments for sulfate-reducing bacteria. The capacity of Methanosarcina to grow diazotrophically was proved with a pure culture in mineral media with methanol. The cell yields with N2 or NH4+ ions as nitrogen source were 2.2 g and 6.1 g dry weight, respectively, per mol of methanol. Growth experiments with 15N2 revealed that 84% of the cell nitrogen was derived from N2. Acetylene was highly toxic to Methanosarcina and only reduced at concentrations lower than 100 μmol dissolved per 1 of medium. Assimilation of N2 and reduction of acetylene were inhibited by NH4+ ions. The experiments show that N2 fixation occurs not only in eubacteria but also in archaebacteria. The ecological significance of diazotrophic growth of Methanosarcina is discussed.

Methane oxidation by Nitrosomonas europaea.

Methane inhibited NH4+ utilization by Nitrosomonas europaea with a Ki of 2mM. O2 consumption was not inhibited. In the absence of NH4+, or with hydrazine as reductant, methane caused nearly a doubling in the rate of O2 uptake. The stimulation was abolished by allylthiourea, a sensitive inhibitor of the oxidation of NH4+. Analysis revealed that methanol was being formed in these experiments, with yields approaching 1 mol of methanol per mol of O2 consumed under certain conditions. When cells were incubated with NH4+ under an atmosphere of 50% methane, 50 microM-methanol was generated in 1 h. It is concluded that methane is an alternative substrate for the NH3-oxidizing enzyme (ammonia mono-oxygenase),m albeit with a much lower affinity than for methane mono-oxygenase of methanotrophs.

Metabolism of H2-CO2, methanol, and glucose by Butyribacterium methylotrophicum.

The fermentative metabolism of Butyribacterium methylotrophicum grown on either H2-CO2, methanol, glucose, or CO is described. The following reaction stoichiometries were obtained: 1.00 H2 + 0.52 CO2 leads to 0.22 acetate + 0.06 cell C; 1 methanol + 0.18 CO2 + 0.01 acetate leads to 0.24 butyrate + 0.29 cell C; and 1.00 glucose leads to 0.31 CO2 + 1.59 acetate + 0.21 butyrate + 0.13 H2 + 1.58 cell C. Cell yields of 1.7 g (dry weight) per mol of H2, 8.2 g (dry weight) per mol of methanol, 42.7 g (dry weight) per mol of glucose, and 3.0 g (dry weight) per mol of CO were obtained from linear plots of cell synthesis and substrate consumption. Doubling times of 9.0, 9.0, and 3 to 4 h were observed during batch growth on H2-CO2, methanol, and glucose, respectively. Indicative of a growth factor limitation, glucose fermentation in defined medium displayed a lower cell synthesis efficiency than when yeast extract (0.05%) was present. B. methylotrophicum fermentation displayed atypically high substrate/cell carbon synthesis conversion ratios for an anaerobe, as greater than 24% of the carbon was assimilated into cells during growth on methanol or glucose. The data indicate that B. methylotrophicum conserves carbon-bound electrons during growth on single-carbon or multicarbon substrates.

Bacterial degradation of 3,4,5-trimethoxyphenylacetic and 3-ketoglutaric acids.

When grown at the expense of 3,4,5-trimethoxyphenylacetic acid, a species of Arthrobacter readily oxidized 3,4-dihydroxy-5-methoxyphenylacetic acid, but other structurally related aromatic acids were oxidized only slowly. Cell extracts contained a dioxygenase for 3,4-dihydroxy-5-methoxyphenylacetate, and the corresponding trihydroxy acid, which was not attacked by the enzyme, inhibited oxidation of this ring-fission substrate. Cell suspensions did not release carbon dioxide from 3,4-[methoxyl-14C]dihydroxy-5-methoxyphenylacetate but accumulated 1 mol of methanol per mol of 3,4,5-trimethoxyphenylacetate oxidized. A cell extract converted the ring-fission substrate into stoichiometric amounts of pyruvate and acetoacetate, formed from 3-ketoglutarate by the action of an induced decarboxylase. 3-Ketoglutaric acid served as sole source of carbon for many soil isolates.