Showing papers on "Methanol published in 1993"

Production of Syngas by Direct Catalytic Oxidation of Methane

Abstract: The reaction between methane and oxygen over platinum and rhodium surfaces in metalcoated ceramic monoliths can be made to produce mostly hydrogen and carbon monoxide (greater than 90% selectivity for both) with almost complete conversion of methane and oxygen at reaction times as short as 10–3 seconds. This process has great promise for conversion of abundant natural gas into liquid products such as methanol and hydrocarbons, which can be easily transported from remote locations. Rhodium was considerably superior to platinum in producing more H2 and less H2O, which can be explained by the known chemistry and kinetics of reactants, intermediates, and products on these surfaces.

A Mercury-Catalyzed, High-Yield System for the Oxidation of Methane to Methanol

Abstract: A homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50 percent, 85 percent selectivity to methyl bisulfate (∼43 percent yield; the major side product is carbon dioxide) was achieved at a molar productivity of 10–7 mole per cubic centimeter per second and Hg(II) turnover frequency of 10–3 per second. Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH3HgOSO3H, 1. Under the reaction conditions, 1 readily decomposes to CH3OSO3H and the reduced mercurous species, Hg22+ The catalytic cycle is completed by the reoxidation of Hg22+ with H2SO4 to regenerate Hg(II) and byproducts SO2 and H2O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.

On the reaction mechanism for propene formation in the MTO reaction over SAPO-34

Abstract: Three different feeds: methanol, methanol/ethanol/water (2 ∶ 1 ∶ 1 molar ratio) and13C-methanol/ethanol/water (2 ∶ 1 ∶ 1) have been converted to hydrocarbons over a SAPO-34 catalyst at 420 °C using argon carrier gas. The products were analyzed by GC-MS allowing the determination of the isotopic composition of the reaction products. The experiments show that the majority of the propene molecules are formed directly from methanol, and that only a minor part is formed by methylation of ethene.

An investigation of titanium dioxide photocatalysis for the treatment of water contaminated with metals and organic chemicals

Abstract: Laboratory experiments were performed to investigate TiO 2 photocatalysis for treating water contaminated with dissolved metals (Ag, Au, Cd, Cr, Cu, Hg, Ni, and Pt) and a variety of organics (e.g., methanol, formic acid, salicylic acid, EDTA, phenol, and nitrobenzene). It was found that only those metals with half-reaction standard reduction potentials more positive than 0.3 V (vs normal hydrogen electrode) can be treated using TiO 2 as the photocatalyst. Kinetic data illustrating the synergism between oxidation and reduction are presented. Experiments using singly substituted benzenes as electron donors show that the rate of reduction of Cr(VI) is correlated with Hammett a constants

Kinetic study of steam reforming of methanol over copper-based catalysts

Abstract: Steam reforming of methanol has been studied over various copper-based catalysts at temperatures from 443 to 533 K. Screening experiments showed that a coprecipitated CuO-ZnO-Al2O3 low-temperature methanol synthesis catalyst had the highest activity and did not deactivate with time on line. It also exhibited 100% selectivity to carbon dioxide and hydrogen (the desired reaction products). Kinetic measurements made over the coprecipitated CuO-ZnO-Al2O3 were found to fit the power law expression: rSR=k0e–105kJ/mol/RTP0.26MeOHP0.03H2OP–0.2H2 Carbon dioxide was found to have no effect on the kinetics of steam reforming of methanol. When carbon monoxide was added to the feed there was negligible influence on the steam reforming reaction with an order of 0.016 being observed.

Process and apparatus for the production of methanol from condensed carbonaceous material

Abstract: An intergrated recycle process for the production of methanol from a process synthesis gas produced by hydrogasification of a condensed carbonaceous feedstock to produce a process gas which is reacted in a steam pyrolysis reactor with additional natural gas and steam to produce said synthesis gas containing hydrogen and carbon monoxide in more than a 2:1 molar ratio which constituents in turn are reacted in a methanol synthesis reactor to produce methanol. The important factor in this process includes the sequence of reactors of the condensed carbonaceous material: a hydrogasification reactor; the stream and natural gas pyrolysis reactor; the methanol synthesis reactor and the recycling to the hydrogasification reactor of the hydrogen-rich gas stream remaining after the methanol synthesis and separation of the methanol product.

Kinetic mechanism for the reaction between methanol and water over a cu-zno-al2o3 catalyst

Abstract: The steam reforming of methanol over a Cu/ZnO/Al 2 O 3 catalyst has been investigated. The reaction yields carbon dioxide and hydrogen in the ratio of one to three, with small amounts of dimethyl ether and carbon monoxide being produced at high conversion. Comparison of the rates of methanol dehydrogenation and of steam reforming over the same catalyst indicate that steam reforming proceeds via dehydrogenation to methyl formate. Methyl formate then hydrolyses to formic acid which decomposes to carbon dioxide and hydrogen. Detailed studies of the kinetics of the reactions show that methanol dehydrogenation controls the rate of steam reforming. Langmuir-Hinshelwood modelling indicates that hydrogen extraction from adsorbed methoxy groups is rate determining to the overall processes.

Aqueous liquid feed organic fuel cell using solid polymer electrolyte membrane

Abstract: A liquid organic fuel cell is provided which employs a solid electrolyte membrane. An organic fuel, such as a methanol/water mixture, is circulated past an anode of a cell while oxygen or air is circulated past a cathode of the cell. The cell solid electrolyte membrane is preferably fabricated from Nafion™. Additionally, a method for improving the performance of carbon electrode structures for use in organic fuel cells is provided wherein a high surface-area carbon particle/Teflon™-binder structure is immersed within a Nafion™/methanol bath to impregnate the electrode with Nafion™. A method for fabricating an anode for use in a organic fuel cell is described wherein metal alloys are deposited onto the electrode in an electro-deposition solution containing perfluorooctanesulfonic acid. A fuel additive containing perfluorooctanesulfonic acid for use with fuel cells employing a sulfuric acid electrolyte is also disclosed. New organic fuels, namely, trimethoxymethane, dimethoxymethane, and trioxane are also described for use with either conventional or improved fuel cells.

On the nature of the active state of silver during catalytic oxidation of methanol

Abstract: Under the applied high reaction temperatures (∼900 K) the Ag surface is restructured and a tightly held oxygen species is formed on the surface (Oγ) apart from O atoms dissolved in the bulk (Oβ). Methanol oxidation to formaldehyde proceeds through this Oγ species as demonstrated by application of a variety of spectroscopic techniques.

Liquid phase methanol process with co-rich recycle

Abstract: Methanol is produced by reacting a CO-rich synthesis gas in the presence of a powdered methanol synthesis catalyst suspended in an inert liquid in a liquid phase reactor system. Unreacted CO-rich synthesis gas is recycled to the reactor, thus increasing methanol production and reducing specific power compared with once-through operation without recycle or compared with recycle of hydrogen-rich gas recovered from unreacted synthesis gas. The process preferably is integrated with a coal gasification electric power generation system in which a portion of the unreacted synthesis gas is used as power generation fuel and a portion of the methanol product is used as additional power generation fuel during periods of peak power demand.

Hydrogenation of CO2 over gold supported on metal oxides

Abstract: Gold highly dispersed on a variety of metal oxides were prepared by coprecipitation and deposition-precipitation methods. The hydrogenation of CO 2 on supported gold catalysts was investigated at temperatures between 150 and 400° C and a pressure of 8 atm. The methanoi yields reached a maximum at temperatures between 200 and 300 ° C, depending on the support oxides. The highest yield and selectivity towards methanol was obtained on Au/ZnO at 250°C. At 200°C Au/Fe 2 O 3 was the most active for methanol synthesis, exhibiting activity almost comparable to that of the conventional Cu/ZnO catalyst with the same metal content. Gold supported on TiO 2 was so active in reducing CO 2 to CO that the conversion was close to equilibrium. Over Au/ZnO as well as over Cu/ZnO, CO 2 could be hydrogenated to methanol at lower temperatures than CO.

Isobaric vapor-liquid equilibria for methanol + ethanol + water and the three constituent binary systems

Abstract: Vapor-liquid equilibrium data for methanol+ethanol+water and its three constituent binary systems methanol+ethanol, ethanol+water, and methanol+water were measured at 101.3 kPa using a liquid-vapor ebullition-type equilibrium still. The experimental binary data were correlated by the NRTL equation. The ternary system methanol+ethanol+water was predicted by means of the binary NRTL parameters with good accuracy

Process for the continuous production of lower alkyl esters of higher fatty acids

Abstract: Production of lower alkyl esters of higher fatty acids from an oil phase and lower alcohols by catalytic transesterification at reaction temperatures of up to 100° C. in the presence of an alkaline catalyst, includes a) introducing a mixture of oil phase, alcohol and catalyst at reaction temperature into the top of a first reactor column, at a rate of flow which is lower than the sinking rate of the glycerine separated from the reaction mixture, b) the reaction mixture is passed into a second reactor for further transesterification, c) the thus obtained reaction mixture is further freed of glycerine in an initial separating stage by means of a short-term washing, d) the reaction mixture is passed into a third reactor with addition of further alcohol and catalyst, and at a rate of flow conforming to the first stage of the process, e) the reaction mixture is further transesterified, f) reaction product is freed of the remaining methanol, glycerine, soaps formed and catalyst in a second separating stage, under addition of an aqueous extraction buffer solution, and g) the reaction mixture is freed of lower alcohols by stripping, washed with suitable extraction and washing solutions and dried.

Formation of surface-bonded methoxy groups in the sorption of methanol and methyl iodide on zeolites studied by carbon-13 MAS NMR spectroscopy

Abstract: Methanol and methyl iodide as methylating agents react chemically with the surface atoms of zeolites and, under favorable conditions, yield surface-bonded methoxy groups. Zeolites with well-defined structures of faujasites, mordenites and ZSM5-containing various cations (Na + , Rb + , Mg 2+ , Ca 2+ ) and /or acid protons were investigated in chemisorption experiments using CH 3 I. The observed signals in the 53-59 ppm TMS region were assigned to the methoxy groups, i.e., methyl groups surface-bonded to the lattice oxygens. The chemical shift of these signals depends linearly on the equalized electronegativity of the oxygen of the given zeolite structure and becomes a measure of the lattice oxygen basicity (nucleophility)

Process for the conversion of methanol to light olefins and catalyst used for such process

Abstract: A zeolite catalyst from ZSM-5 modified with phosphorus, rare earth elements and pore structure regulator is used for methanol/dimethyl ether conversion to light olefins. High temperature, non-recycling, continuous-running process is realized in the reactor system, comprising a dehydration reactor and several (2-n) adiabatic, fixed bed cracking reactors, loaded with the catalyst in multi-stage packing and operated in reaction regeneration cycles. The catalyst possesses high activity, high selectivity, good hydrothermal stability and long reaction life time. Operation of 100% methanol conversion and >85% C 2 -C 4 selectivity has been performed in a reactor system of the scale 0.7-1 ton CH 3 OH/day for >600 hours on stream and with reaction time of single cycle >24 hours.

High-pressure vapor-liquid equilibria for carbon dioxide + methanol, carbon dioxide + ethanol, and carbon dioxide + methanol + ethanol

Abstract: This work was supported by the Korea Science and Engineering Foundation and University Awards Program of the Korea Advanced Institute of Science and Technology

Catalytic Dehydration of Methanol to Dimethyl Ether. Kinetic Investigation and Reactor Simulation

Abstract: One-dimensional heterogeneous and pseudohomogeneous plug flow models were employed to model an adiabatic fixed bed reactor for the catalytic dehydration of methanol to dimethyl ether. Longitudinal temperature and methanol conversion profiles predicted by these models were compared to those experimentally measured in a pilot reactor. The reactor was packed with 3-mm [gamma]-Al[sub 2]O[sub 3] pellets and operated in a temperature range of 290--360 C and at a pressure of 2.1 bar. Intraparticle mass transport was found to be the rate-controlling step.

Process for separating alcohols from mixtures of alcohols, water and other compounds

Abstract: From a mixture containing methanol, ethanol, n-propanol, isobutanol water and other high-boiling and low-boiling compounds, the claimed process enables three separate streams to be obtained, one an anhydrous stream of methanol or methanol and ethanol (I), one containing most of the n-propanol present in the feed mixture (II), and one containing most of the isobutanol present in the feed mixture (III), by using three fractionating columns.

Complete oxidation of ethanol, acetaldehyde and ethanol/methanol mixtures over copper oxide and copper-chromium oxide catalysts

Abstract: With the Clean Air Act amendments of 1990 requiring increased use of oxygenated compounds such as alcohols and ethers in motor fuels, the problem of effectively controlling the emissions caused by burning these substances has become a more pressing issue. Complete oxidation of ethanol, acetaldehyde, and a methanol-ethanol mixture over supported copper oxide, chromium oxide, and copper oxide/chromium oxide catalysts was investigated using a gradientless external recycle reactor. The catalysts were characterized by BET surface area measurement, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. The effect of catalyst type and composition, reaction temperature, and feed composition has been examined.

Ruthenium complex catalysed hydrogenation of carbon dioxide to carbon monoxide, methanol and methane

Abstract: A novel hydrogenation of carbon dioxide proceeds in with presence of a Ru3(CO)12–KI homogeneous catalytic system with successive formation of carbon monoxide, methanol and methane.

Intermediate species on zirconia supported methanol aerogel catalysts: II. Adsorption of carbon monoxide on pure zirconia and on zirconia containing zinc oxide

Abstract: On pure ZrO2 and on ZnO/ZrO2 aerogels carbon monoxide interacts with the surface hydroxyl groups to form surface formate species. This species is relatively stable on pure ZrO2 where it is decomposed at increasing temperatures either resulting in regeneration of carbon monoxide and of surface OH's or in carbon dioxide and hydrogen. Only this second path is observed on ZnO/ZrO2 aerogel and it is paralleled by the formation on the surface of carbonate type species like unidented carbonate, carboxylate and ionic carbonate. This difference in the fate of the formate species onto the previous catalysts may bear some connection with the controversial problem of the pivotal species in the methanol synthesis, the formate of the carbonate type species.