Methanol Synthesis Reaction Research Articles

In situ IR studies on the mechanism of methanol synthesis over an ultrafine Cu/ZnO/Al 2O 3 catalyst

Methanol synthesis from CO 2 and CO/CO 2 hydrogenation was carried out under real reaction conditions over an ultrafine Cu/ZnO/Al 2O 3 (Cu/Zn/Al=60/30/10, molar ratio) catalyst. The formation and variation of surface species were recorded by in situ FT-IR spectroscopy. The mechanisms of methanol synthesis and RWGS reaction were discussed. The result revealed that methanol was formed directly from CO 2 hydrogenation for CO 2/H 2 or CO/CO 2/H 2 reaction systems. b-HCOO − s was the necessary intermediate for methanol synthesis. A scheme of methanol and RWGS reaction was proposed.

Electron Spectroscopic Studies of CH3OH Chemisorption on Cu2O and ZnO Single-Crystal Surfaces: Methoxide Bonding and Reactivity Related to Methanol Synthesis

Adsorption of CH3OH on Cu2O(111), ZnO(0001), and ZnO(1010) has been investigated with XPS, NEXAFS, variable-energy photoelectron spectroscopy (PES), and SCF-Xα Scattered Wave (SW) molecular orbital calculations. At high coverage (≥25.0L), CH3OH is adsorbed as molecular multilayers on all three surfaces. At low temperatures (140 K) and coverage (0−0.6L), CH3OH is deprotonated to form chemisorbed methoxide on all of the surfaces investigated. Under these conditions the C1s XPS peak positions are 289.5, 290.2, and 290.2 eV below the vacuum level, respectively. Annealing the CH3O-/Cu2O(111) surface complex to 523 K produces no other surface intermediate. Alternatively, at temperatures above 220 K on the ZnO(0001) surface methoxide decomposes to produce a formate intermediate that is stable at the methanol synthesis reaction temperature (523 K). No formate surface intermediate is observed on the ZnO(1010) surface. The NEXAFS spectrum of chemisorbed methoxide on the Cu2O(111) surface exhibits a σ* shape resonan...

In situ FTIR study on hydrogenation of carbon dioxide over titania-supported copper catalysts

The effects of co-catalyst were studied on the methanol-synthesis reaction from carbon dioxide and hydrogen over various TiO 2-supported copper catalysts. The catalytic activities with a continuous flow reactor were measured together with in situ infrared spectra at the elevated temperature and pressure. Phosphorus did not show any activity. Potassium showed a high activity but promoted CO formation. ZnO had a high activity and a high methanol selectivity. ZrO 2 also showed promotion effect to some extent. By in situ Fourier transform infrared spectroscopy (FTIR), the formate species formed on Cu was observed over CuO/TiO 2 catalyst. The amount of the formate species depended on the kinds of additive. Addition of K, Zr and Zn showed high activity and increased the intensities of the formate species. On the other hand, addition of P decreased the activity and the intensities of the formate species. Among them, Zn addition increased the amount of adsorbed formate species markedly and obtained the highest methanol yield.

Effect of the addition of chromium- and manganese oxides on structural and catalytic properties of copper/zirconia catalysts for the synthesis of methanol from carbon dioxide

The effect of chromium- and manganese oxide on the structural and catalytic properties of copper/zirconia used for methanol synthesis from carbon dioxide and hydrogen has been investigated by several techniques ( TG DTA , XRD, TPR, XPS, N 2O-titration, nitrogen physisorption). The methanol selectivity of all catalysts is governed by the competition of the simultaneously catalyzed methanol synthesis and reverse water gas shift reaction. The chromium containing sample produces predominantly methanol, whereas the manganese containing catalyst is most active for CO formation. For reaction temperatures 443–513 K and 1.7 MPa total pressure, methanol formation decreases in the order Cu/ZrO 2 > Cu/CrO x /ZrO 2 > Cu/MnO x /ZrO 2 for catalysts dried at 403 K. After calcination at 623 K in air, methanol synthesis activity is similar for all catalysts. For temperatures exceeding 523 K Cu/CrO x /ZrO 2 shows highest activity for methanol production. The addition of chromium oxide and less pronounced manganese oxide, to Cu ZrO 2 retards sintering of the copper component and shifts the crystallization of amorphous zirconia to higher temperatures, thus, resulting in an increased thermal stability of the catalyst under reaction conditions. X-ray photoelectron spectroscopy (XPS) was applied to examine the relative surface concentrations and the oxidation state of the catalyst components. XPS shows that there is no apparent correlation between the oxidation states of the metals and the catalytic properties of the catalysts. In situ diffuse reflectance FTIR studies were performed to identify the species present on the catalyst surface under CO 2 hydrogenation conditions and to elucidate the reaction mechanism. With all catalysts, surface carbonate and formate species were formed rapidly. Evidence is given that over copper/zirconia based catalysts methanol is formed mainly from bidentate surface carbonate via adsorbed CO, π-bound formaldehyde and surface-bound methylate.

97/04613 Petrochemicals from coal-derived syngas: Sardesai, A. and Lee, S. Proc. Annu. Int. Pittsburgh Coal Conf., 1996, 13, (1), 565–570

The development of the Liquid Phase Dimethyl Ether (LPDME) process has established a means to effectively convert CO-rich syngas to dimethyl ether (DME) in a mechanically agitated slurry reactor. By operating in a dual catalyst mode, in-situ produced methanol may be converted to DME, thereby alleviating the chemical equilibrium limitation imposed on the methanol synthesis reaction. As a result, higher syngas conversions and methyl productivities are seen over methanol synthesis alone. This effective route to DME production over methanol has led to the development of conversion technologies based on a DME feedstock. Oxygenates, in particular, ethers and their precursors, are very important as potential clean fuel additives and have been postulated through vinylation/hydrogenation and oxidative coupling reactions. Specialty chemicals such as methyl acetate and acetic acid have widescale industrial importance in the conversion to ethanol from a non-agricultural feedstock. Vapor phase oxidative dimerization of DME over tin based catalysts produced precursors of ethylene glycol. Finally, DME has been extensively used as a feedstock for hydrocarbon synthesis including olefins, paraffins and gasoline range hydrocarbons, over zeolite based catalysts with a 46% increase in product selectivity over methanol. The efficient production of DME in the liquid phase has given it widescale industrialmore » significance as a potential replacement for methanol and as a keystone for more important petrochemicals.« less

Hynol—An economical process for methanol production from biomass and natural gas with reduced CO 2 emission

The Hynol process is proposed to meet the demand for an economical process for methanol production with reduced CO 2 emission. This new process consists of three reaction steps: (a) hydrogasification of biomass, (b) steam reforming of the produced gas with additional natural gas feedstock, and (c) methanol synthesis of the hydrogen and carbon monoxide produced during the previous two steps. The H 2-rich gas remaining after methanol synthesis is recycled to gasify the biomass in an energy neutral reactor so that there is no need for an expensive oxygen plant as required by commercial steam gasifiers. Recycling gas allows the methanol synthesis reactor to perform at a relatively lower pressure than conventional while the plant still maintains high methanol yield. Energy recovery designed into the process minimizes heat loss and increases the process thermal efficiency. If the Hynol methanol is used as an alternative and more efficient automotive fuel, an overall 41% reduction in CO 2 emission can be achieved compared to the use of conventional gasoline fuel. A preliminary economic estimate shows that the total capital investment for a Hynol plant is 40% lower than that for a conventional biomass gasification plant. The methanol production cost is $0.43/gal for a 1085 million gal/yr Hynol plant which is competitive with current U.S. methanol and equivalent gasoline prices. Process flowsheet and simulation data using biomass and natural gas as cofeedstocks are presented. The Hynol process can convert any condensed carbonaceous material, especially municipal solid waste (MSW), to produce methanol.

Alcohol synthesis in a high-temperature slurry reactor

A family of hydrocarbon liquids has been discovered that is stable at temperatures up to about 400°C in the presence of synthesis gas. The performance of a commercial, ‘zinc chromite’, ‘high pressure’ methanol synthesis catalyst was evaluated in a slurry reactor using two of these liquids, decahydronaphthalene and tetrahydronaphthalene, to suspend the catalyst. The evaluation covered a range of temperatures from 275° to 425°C, total pressures from 6.9 to 17.2 MPa, H 2/CO ratios from 0.5 to 2.0 and space velocities from 1500 to 10 000 sl kg(catalyst) −1 h −1. Methanol was the only significant product at the lower end of this temperature range. The methanol synthesis reaction was close to equilibrium at the highest temperature, and there were significant quantities of dimethyl ether, olefins, methane and carbon dioxide in the product. Catalyst performance was sensitive to the composition of the slurry liquid, but was relatively stable in decahydronaphthalene over a long period of time.

Change of catalytic properties of Fe [sbnd]ZnO/zeolite composite catalyst in the hydrogenation of carbon dioxide

The hydrogenation of carbon dioxide was examined using the composite catalysts which were obtained by the physical mixing of Fe ZnO and HY zeolite. Fe ZnO was a typical F-T (Fischer-Tropsch) catalyst and Fe ZnO/HY is a composite catalyst which is able to induce a combined methanol synthesis and MTG (Methanol-to-Gasoline) reaction. To study these unique catalytic behaviors of Fe ZnO/HY, the adsorption and the dissociation of carbon monoxide on Fe ZnO as well as TPR measurements were carried out. Fe ZnO is able to produce hydrocarbons by F-T reaction and methanol. In the absence of zeolite, Fe ZnO exerts its ability for F-T reaction. However, HY diminishes the activity for F-T reaction and hydrocarbons were obtained via methanol formed over the modified Fe ZnO

Kinetic Implications of Dynamical Changes in Catalyst Morphology during Methanol Synthesis over Cu/ZnO Catalysts

In this paper a dynamic microkinetic model of the methanol synthesis reaction over Cu/ZnO catalysts is described. The model is based on surface science measurements and it includes the dynamic changes in particle shape and active surface area which have recently been observed byin situEXAFS measurements to take place upon change in the redox potential of the reaction gas. It is suggested that the change in particle morphology is related to a change in the number of oxygen vacancies at the Zn–O–Cu interface. Furthermore, the structure sensitivity of the methanol synthesis reaction is also taken into account. The dynamic microkinetic model is seen to give a much better description of the kinetic measurements over a working methanol catalyst compared to a static microkinetic model. The new model also gives an explanation of the kinetic behavior during transient conditions. The dynamic aspects are seen to provide a basis for understanding the apparently conflicting reaction orders reported in the literature.

The role of IGCC in CO2 abatement

Abstract IGCC technology per se involves the potential of highest efficiencies, thus reducing the CO 2 output accordingly. Moreover, the intermediate stage of synthesis gas makes it possible to remove most of the carbon compounds before combustion with acceptable additional auxiliary power demand. The separated CO 2 stream is of highest purity and therefore suited for disposal e.g. in the deep sea or for reuse in chemical syntheses. So, methanol synthesis based on power plant CO 2 has been investigated. This contribution presents the results of a pre-basic design for a coal-fired 300 MW-class IGCC power plant with methanol production using an external H 2 source. Based on a Siemens Model V94.3A gas turbine-generator, the standard IGCC has been equipped with plant components including CO shift reactors, CO 2 scrubber, methanol synthesis reactors and distillation unit; additional investment costs amount to approx. 25 %. This concept is based solely on proven process engineering methods. Primary energy utilization as well as the resulting methanol production costs based on appropriate generating costs are discussed. Comparative CO 2 emission figures make the advantage of such a coproduction process regarding this perfectly clear.

The STAR configuration for methanol synthesis in reversed flow reactors

AbstractAlthough the transient reversed flow operation of a fixed bed reactor for methanol synthesis was shown to be an economically attractive alternative for the traditional steady state technology, it suffers from strongly varying exit concentrations upon flow reversal. These not only disturb the operation of downstream equipment but also significantly decrease the time averaged conversion to methanol.To avoid this drawback, the STAR reactor concept is introduced. It operates in a fully transient mode, but combines the attractive features of the reversed flow reactor operation with practically constant exit concentrations. Extensive simulation work shows that the conversions obtained exceed those of the single reversed flow reactor by at least 5 percent.

Alcohol synthesis with [formula omitted] catalysts in a slurry reactor

A laboratory stirred autoclave reactor has been developed to operate at temperatures up to 375°C and pressures of at least 170 atma. The performance of a commercial “high pressure” methanol synthesis catalyst, the so-called “zinc chromite” catalyst, has been characterized over a range of temperature from 300 to 375°C, pressures from 68 to 174 atma, H 2 CO ratios from 0.5 to 2.0 and space velocities from 1500 to 10000 sL/kg(catalyst)-hr. Towards the lower end of the temperature range, methanol was the only significant product. At the highest temperatures, the methanol synthesis reaction was close to equilibrium. There were significant quantities of methane, dimethyl ether and olefins in the product at these temperatures. Formation of higher alcohols was insignificant, although small amounts of isobutanol were formed at the highest temperatures and pressures, with 10 mole percent CO 2 in the feed gas.

Modelling of equilibrium limited hydrogenation reactions carried out in H + conducting solid oxide membrane reactors

A model is prepared for the hydrogenation reactions of ammonia and methanol synthesis that are carried out in solid electrolyte cell-reactors. Hydrogen is supplied in the form of H + through the proton conducting wall and the thermodynamic activity of hydrogen on the catalyst surface is controlled electrochemically. Under certain conditions, the yield of the cell-reactor is orders of magnitude higher than that of the corresponding conventional catalytic reactor. The key parameters that effect the product yield of either reaction are identified and their role is discussed.

The Carnol process for CO 2 mitigation from power plants and the transportation sector

A CO 2 mitigation process is developed which converts waste CO 2, primarily recovered from coal-fired power plant stack gases with natural gas, to produce methanol as a liquid fuel and coproduct carbon as a materials commodity. The Carnol process chemistry consists of methane decomposition to produce hydrogen which is catalytically reacted with the recovered waste CO 2 to produce methanol. The carbon is either stored or sold as a materials commodity. A process design is modelled and mass and energy balances are presented as a function of reactor pressure and temperature conditions. The Carnol process is a viable alternative to sequestering CO 2 in the ocean for purposes of reducing CO 2 emissions from coal burning power plants. Over 90% of the CO 2 from the coal burning plant is used in the process which results in a net CO 2 emission reduction of over 90% compared to that obtained for conventional methanol production by steam reforming of methane. Methanol as an alternative liquid fuel for automotive engines and for fuel cells achieves additional CO 2 emission reduction benefits. The economics of the process is greatly enhanced when carbon can be sold as a materials commodity. Improvement in process design and economics should be achieved by developing a molten metal (tin) methane decomposition reactor and a liquid phase, slurry catalyst, methanol synthesis reactor directly using the solvent saturated with CO 2 scrubbed from the power plant stack gases. The benefits of the process warrants its further development.

Hydrogenation of carbon dioxide over copper-pyrochlore/zeolite composite catalysts

The hydrogenation of CO 2 was studied over composite catalysts obtained by mixing Cu-based methanol synthesis catalyst and HY zeolite. A mechanism associating methanol synthesis and MTG (methanol to gasoline) reaction allowed the formation of C 1-C 4 hydrocarbons. It was found that the catalytic behaviors of the composite catalysts were favorably influenced by the characteristics of the methanol synthesis catalysts. The Cu-La 2Zr 2O 7 catalyst we recently developed associated with HY zeolite exhibited interesting performances in hydrocarbon synthesis. The addition of ZrO 2 to CuLa 2Zr 2O 7/HY enhanced the ability to produce hydrocarbons. Comparing composite catalyst systems prepared with different Cu-based methanol synthesis catalysts, the effect of Na contamination on methanol and hydrocarbon formation over composite catalysts were also discussed.

A membrane reactor for methanol synthesis

Methanol synthesis from CO 2 and H 2 is a promising chemical energy storage reaction for hydrogen. The methanol yield of the synthesis is limited by the thermodynamic equilibrium at the temperatures required by state-of-the-art catalysts. Substantial conversion improvements would be achieved by selective product separation from the catalyst bed of a synthesis reactor. A perfluorinated cation exchange material (Nafion ®, DuPont) is evaluated for use as a vapour permeation membrane at temperatures up to 200°C. The permselectivities for methanol and water with respect to hydrogen depend on the counter ion in the polymer, and drop as a function of temperature. With respect to long term stability and performance, lithium is best suited as a counter ion, with permselectivities of 32 for water, and 5.6 for methanol, respectively. Permeability and permselectivity are found to increase with increasing partial pressures of both methanol and water vapours. The capability of the Li-Nafion membrane to separate products from a commercially available catalyst bed operating on CO 2 and H 2 at 200°C is demonstrated using a simple tubular membrane reactor module.

The Carnol process for CO2 mitigation from power plants and the transportation sector

Abstract A CO2 mitigation process is developed which converts waste CO2, primarily recovered from coal-fired power plant stack gases with natural gas, to produce methanol as a liquid fuel and coproduct carbon as a materials commodity. The Carnol process chemistry consists of methane decomposition to produce hydrogen which is catalytically reacted with the recovered waste CO2 to produce methanol. The carbon is either stored or sold as a materials commodity. A process design is modelled and mass and energy balances are presented as a function of reactor pressure and temperature conditions. The Carnol process is a viable alternative to sequestering CO2 in the ocean for purposes of reducing CO2 emissions from coal burning power plants. Over 90% of the CO2 from the coal burning plant is used in the process which results in a net CO2 emission reduction of over 90% compared to that obtained for conventional methanol production by steam reforming of methane. Methanol as an alternative liquid fuel for automotive engines and for fuel cells achieves additional CO2 emission reduction benefits. The economics of the process is greatly enhanced when carbon can be sold as a materials commodity. Improvement in process design and economics should be achieved by developing a molten metal (tin) methane decomposition reactor and a liquid phase, slurry catalyst, methanol synthesis reactor directly using the solvent saturated with CO2 scrubbed from the power plant stack gases. The benefits of the process warrants its further development.

A Fourier-transform infrared study of CO2 and CO2/H2 interactions with caesium-doped copper catalysts

FTIR spectra are reported of CO2 and CO2/H2 on a silica-supported caesium-doped copper catalyst. Adsorption of CO2 on a “caesium”/silica surface resulted in the formation of CO2− and complexed CO species. Exposure of CO2 to a caesium-doped reduced copper catalyst produced not only these species but also two forms of adsorbed carboxylate giving bands at 1550, 1510, 1365 and 1345 cm−1. Reaction of carboxylate species with hydrogen at 388 K gave formate species on copper and caesium oxide in addition to methoxy groups associated with caesium oxide. Methoxy species were not detected on undoped copper catalyst suggesting that caesium may be a promoter for the methanol synthesis reaction. Methanol decomposition on a caesium-doped copper catalyst produced a small number of formate species on copper and caesium oxide. Methoxy groups on caesium oxide decomposed to CO and H2, and subsequent reaction between CO and adsorbed oxygen resulted in carboxylate formation. Methoxy species located at interfacial sites appeared to exhibit unusual adsorption properties.

Light alkenes from syngas via dimethyl ether

A new route, named the SDTO method, for the synthesis of light alkenes from syngas is proposed. The method consists of the conversion of syngas to dimethyl ether, followed by the conversion of dimethyl ether to light alkenes. Catalysts for the two reactions have been developed. For the first reaction, the catalyst was synthesized by combining a methanol synthesis catalyst with λ-Al 2O 3 or zeolites, which possess both metallic and acidic functions. The conversion of the reaction is much higher than that of the methanol synthesis reaction. Suitable reaction conditions are: 210–280°C; P>.0MPa and gas hourly space velocity (GHSV) < 1500 h −1. The catalyst for the second reaction was a modified SAPO-34 molecular sieve. The effects of the modification on the catalyst and the factors influencing the reaction have been investigated. A fluid bed reactor is considered to be a suitable reactor type for these catalysts. Under the reaction conditions of 550°C and weight hourly space velocity (WHSV MeOH) > 6 h −1 or line velocity of MeOH> 15, the selectivity for ethylene and total light alkenes are ca. 60 and ca. 90, respectively (conversion= 100%). The stability of the modified SAPO-34 catalyst has been tested under severe conditions. The results from the serial connection of the two conversion steps without any separation show that the yield of C 2 =–C 4 = alkenes could be > 100 g/(m 3 syngas).

Methanol synthesis and water-gas shift reactions on Raney copper catalysts

The use of Raney copper to catalyse the synthesis of methanol and the water-gas shift reaction is reviewed. The preparation of Raney copper and Raney copper-zinc alloys together with their leaching to form active catalysts is first considered. The production of methanol is promoted by copper and the major—but not the only—role of zinc oxide involves the production of higher and more stable copper surface areas. There is some evidence that the catalytic activity of both methanol synthesis and water-gas shift may be improved by events occurring at the CuZnO interface. It is now clear that carbon dioxide is the major reactant forming methanol under industrial conditions. Both in the water-gas shift and the synthesis reactions, formates appear to be the main intermediates. Raney catalysts have the advantages of high mechanical strength, of regenerability and of producing less side products during methanol synthesis—an important practical consideration. Their applicability to industrial operations would seem advantageous.