US 2010.0193370A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2010/0193370 A1 OLAH et al. (43) Pub. Date: Aug. 5, 2010
(54) ELECTROLYSIS OF CARBON DIOXIDE IN Publication Classification AQUEOUSMEDIATO CARBON MONOXIDE AND HYDROGEN FOR PRODUCTION OF (51) Int. Cl. METHANOL C25B 3/00 (2006.01) (52) U.S. Cl...... 205/450 (76) Inventors: George A. OLAH, Beverly Hills, CA (US); G.K. Surya PRAKASH, (57) ABSTRACT Hacienda Heights, CA (US) An environmentally beneficial method of producing metha Correspondence Address: nol from varied sources of carbon dioxide including flue WINSTON & STRAWN LLP gases of fossil fuel burning power plants, industrial exhaust PATENT DEPARTMENT gases or the atmosphere itself. Converting carbon dioxide by 1700 KSTREET, N.W. an electrochemical reduction of carbon dioxide in a divided WASHINGTON, DC 20006 (US) electrochemical cell that includes an anode in one compart ment and a metal cathode electrode in a compartment that also (21) Appl. No.: 12/754,952 contains an aqueous solution comprising methanol and an electrolyte. An anion-conducting membrane can be provided (22) Filed: Apr. 6, 2010 between the anode and cathode to produce at the cathode therein a reaction mixture containing carbon monoxide and Related U.S. Application Data hydrogen, which can be Subsequently used to produce metha nol while also producing oxygen in the cell at the anode. The (63) Continuation-in-part of application No. 12/171,904, oxygen produced at the anode can be recycled for efficient filed on Jul. 11, 2008, now Pat. No. 7,704,369. combustion of fossil fuels in power plants to exclusively (60) Provisional application No. 60/949,723, filed on Jul. produce CO exhausts for capture and recycling as the Source 13, 2007. of CO, for the cell. The Methanol Economy Process
SSS S88:S&SSSSSSSS &issisi &isssssssses & Patent Application Publication Aug. 5, 2010 Sheet 1 of 2 US 2010/0193370 A1
Methanol derived chemical products and materials
Methyl tert-butyl ether (MTBE)
Methane-di-isocyanate (MDI)
HCN
EelDimethyl formamide (DMF( ) Methylethonolomine Dimethylacetamide (DMAC) Tetromethyl Ommonium hydroxide (TMAH( ) OrbOmotes H ig h e r O in e S Dimethyl(DMT) terephthalate Polyethyleneterephthalate (PET) Dimethyl ether (DME) ydrogen H2 Carbon monoxide CO Single cell proteins Biochemicolss PRIOR ART Others FIG 1 Patent Application Publication Aug. 5, 2010 Sheet 2 of 2 US 2010/0193370 A1
The Methanol Economy Process
S$ 88: 8:38 US 2010/0193370 A1 Aug. 5, 2010
ELECTROLYSIS OF CARBON DOXDE IN methanol's energy content is lower, it has a higher octane AQUEOUSMEDIATO CARBON MONOXIDE rating of 100 (average of the research octane number (RON) AND HYDROGEN FOR PRODUCTION OF of 107 and motor octane number (MON) of 92), which means METHANOL that the fuel/air mixture can be compressed to a smaller vol ume before being ignited. This allows the engine to run at a higher compression ratio (10-11 to 1 against 8-9 to 1 of a 0001. This application is a continuation-in-part of appli gasoline engine), more efficiently than a gasoline-powered cation Ser. No. 12/171,904 filed Jul. 11, 2008, which claims engine. Efficiency is also increased by methanol's higher the benefit of provisional application No. 60/949,723 filed “flame speed,” which enables faster, more complete fuel com Jul. 13, 2007, the entire content of each of which is expressly bustion in the engines. These factors explain the high effi incorporated herein by reference thereto. ciency of methanol despite its lower energy density than BACKGROUND gasoline. Further, to render methanol more ignitable even under the most frigid conditions, methanol can be mixed with 0002 Hydrocarbons are essential in modern life. Hydro gasoline, with Volatile compounds (e.g., dimethyl ether), with carbons are used as fuel and raw material in various fields, other components or with a device to vaporize or atomize including the chemical, petrochemical, plastics, and rubber methanol. For example, an automotive fuel can be prepared industries. Fossil fuels, such as coal, oil and gas, are com by adding methanol to gasoline with the fuel having a mini posed of hydrocarbons with varying ratios of carbon and hydrogen, and is non-renewably used when combusted, form mum gasoline content of at least 15% by volume (M85 fuel) ing carbon dioxide and water. Despite their wide application so that it can readily start even in low temperature environ and high demand, fossil fuels present a number of disadvan ments. Of course, any replacement of gasoline in Such fuels tages, including the finite reserve, irreversible combustion will conserve oil resources, and the amount of methanol to and contribution to air pollution and global warming. Con add can be determined depending upon the specific engine sidering these disadvantages, and the increasing demand for design. energy, alternative sources of energy are needed. 0007 Methanol has a latent heat of vaporization of about 0003. One such alternative frequently mentioned is hydro 3.7 times higher than gasoline, and can absorb a significantly gen, and the so-called "hydrogen economy.” Hydrogen is larger amount of heat when passing from liquid to gas state. beneficial as a clean fuel, producing only water when com This helps remove heat away from the engine and enables the busted. Free hydrogen, however, is not a natural energy use of an air-cooled radiator instead of a heavier water-cooled Source, and its generation from hydrocarbons or water is a system. Thus, compared to a gasoline-powered car, a metha highly energy-consuming process. Further, when hydrogenis nol-powered engine provides a smaller, lighter engine block, produced from hydrocarbons, any claimed benefit of hydro reduced cooling requirements, and better acceleration and gen as a clean fuel is outweighed by the fact that generation of mileage capabilities. Methanol is also more environment hydrogen itself, mainly by reforming of natural gas, oil or friendly than gasoline, and produces low overall emissions of coal to synthesis gas (“syn-gas') a mixture of CO and H, is air pollutants such as hydrocarbons, NO, SO and particu far from clean. It consumes fossil fuels, with a quarter of the lates. energy of the fuel being lost as heat. Hydrogen is also not a 0008 Methanol is also one of the safest fuels available. convenient energy storage medium because it is difficult and Compared to gasoline, methanol's physical and chemical costly to handle, store, transport and distribute. As it is properties significantly reduce the risk of fire. Methanol has extremely volatile and potentially explosive, hydrogen gas lower volatility, and methanol vapor must be four times more requires high-pressure equipment, costly and non-existent concentrated than gasoline for ignition to occur. Even when infrastructure, special materials to minimize diffusion and ignited, methanol burns about four times slower than gaso leakage, and extensive safety precautions to prevent explo line, releases heat only at one-eighth the rate of gasoline fire, sions. and is far less likely to spread to Surrounding ignitable mate 0004. It was suggested that a more practical alternative is rials because of the low radiant heat output. It has been esti methanol. Methanol, CHOH, is the simplest liquid oxygen mated by the EPA that switching from gasoline to methanol ated hydrocarbon, differing from methane (CH4) by a single would reduce incidence of fuel-related fire by 90%. Methanol additional oxygen atom. Methanol, also called methyl alco burns with a colorless flame, but additives can solve this hol or wood alcohol, is a colorless, water-soluble liquid with problem. a mild alcoholic odor, and is easy to store and transport. It 0009 Methanol also provides an attractive and more envi freezes at -97.6°C., boils at 64.6°C., and has a density of ronment-friendly alternative to diesel fuel. Methanol does not O.791 at 20° C. produce Smoke, Soot, or particulates when combusted, in 0005 Methanol is not only a convenient and safe way to contrast to diesel fuel, which generally produces polluting store energy. Methanol either can be blended with gasoline or particles during combustion. Methanol also produces very diesel and used as fuels, for example in internal combustion low emissions of NOx because it burns at a lower temperature engines or electricity generators. One of the most efficient use than diesel. Furthermore, methanol has a significantly higher of methanol is in fuel cells, particularly in direct methanol vapor pressure compared to diesel fuel, and the higher Vola fuel cell (DMFC), in which methanol is directly oxidized with tility allows easy start even in cold weather, without produc air to carbon dioxide and water while producing electricity. ing white Smoke typical of cold start with a conventional 0006 Contrary to gasoline, which is a complex mixture of diesel engine. If desired, additives orignition improvers. Such many different hydrocarbons and additives, methanol is a as octyl nitrate, tetrahydrofurfuryl nitrate, peroxides or higher single chemical compound. It contains about half the energy alkyl ethers, can be added to bring methanol's cetane rating to density of gasoline, meaning that two liters of methanol pro the level closer to diesel. Methanol can also be used in the vides the same energy as a liter of gasoline. Even though manufacture of biodiesel fuels by esterification offatty acids. US 2010/0193370 A1 Aug. 5, 2010
0010 Closely related and derived from methanol, and also hydrogen at -253° C.), methanol is an excellent carrier of a desirable alternative fuel is dimethyl ether. Dimethyl ether is hydrogen fuel. The absence of C–C bonds in methanol, easily obtained by methanol dehydration. Dimethyl ether which are difficult to break, facilitates its transformation to (DME, CHOCH), the simplest of all ethers, is a colorless, pure hydrogen with 80 to 90% efficiency. nontoxic, non-corrosive, non-carcinogenic and environmen 0015. In contrast to a pure hydrogen-based storage sys tally friendly chemical that is mainly used today as anaerosol tem, a reformer system is compact, containing on a Volume propellant in spray cans, in place of the banned CFC gases. basis more hydrogen than even liquid hydrogen, and is easy to DME has a boiling point of -25° C., and is a gas under store and handle without pressurization. A methanol steam ambient conditions. DME has no propensity to form perox reformer is also advantageous in allowing operation at a much ides unlike higher homologous ethers. DME is, however, lower temperature (250-350° C.) and for being better adapted easily handled as liquid and stored in pressurized tanks, much to on-board applications. Furthermore, methanol contains no like liquefied petroleum gas (LPG). The interest in dimethyl Sulfur, a contaminant for fuel cells, and no nitrogen oxides are ether as alternative fuel lies in its high cetane rating of 55 to formed from a methanol reformer because of the low operat 60, which is much higher than that of methanol and is also ing temperature. Particulate matter and NO emissions are higher than the cetane rating of 40 to 55 of conventional diesel virtually eliminated, and other emissions are minimal. More fuels. The cetane rating indicates that DME can be effectively over, methanol allows refueling to be as quick and easy as used in diesel engines. Advantageously, DME, like methanol, with gasoline or diesel fuel. Thus, an on-board methanol is clean burning, and produces no soot particulates, black reformer enables rapid and efficient delivery of hydrogen smoke or SO, and only very low amounts of NO, and other from liquid fuel that can be easily distributed and stored in the emissions even without after-treatment of its exhaust gas. vehicle. To date, methanol is the only liquid fuel that has been Some of the physical and chemical properties DME, in com processed and demonstrated on a practical scale as Suitable parison to diesel fuel, are shown in Table 1. for fuel use in a fuel cell for transportation applications. 0016. In addition to on-board reforming, methanol also TABLE 1. enables convenient production of hydrogen in fueling stations for refueling hydrogen fuel cell vehicles. A fuel cell, an elec Comparison of the physical properties of DME and diesel fuel trochemical device that converts free chemical energy of fuel DME Diesel fuel directly into electrical energy, provides a highly efficient way Boiling point C. -24.9 18O-360 of producing electricity via catalytic electrochemical oxida Vapor pressure at 20°C. (bar) 5.1 tion. For example, hydrogen and oxygen (air) are combined in Liquid density at 20° C. (kg/m) 668 840-890 an electrochemical cell-like device to produce water and elec Heating value (kcal/kg) 6,880 10,150 tricity. The process is clean, with water being the only Cetane number SS-60 40-5S Autoignition temperature (C.) 235 200-300 byproduct. However, because hydrogen itself must first be Flammability limits in air (vol%) 34-17 O6-6.5 produced in an energy-consuming process, by electrolysis or from a hydrocarbon source (fossil fuel) with a reformer, hydrogen fuel cells are still necessarily limited in utility. 0011 Currently, DME is exclusively produced by dehy 0017. A system for producing high purity hydrogen has dration of methanol. A method for synthesizing DME directly been developed by steam reforming of methanol with a highly from synthesis gas by combining the methanol synthesis and active catalyst, which allows operation at a relatively low dehydration steps in a single process has also been developed. temperature (240-290° C.) and enables flexibility in opera 0012 Another methanol derivative is dimethyl carbonate tion as well as rapid start-up and stop. These methanol-to (DMC), which can be obtained by converting methanol with hydrogen (MTH) units, ranging in production capacity from phosgene or by oxidative carbonylation of the methanol. 50 to 4000 mH. per hour, are already used in various indus DMC has a high cetane rating, and can be blended into diesel tries, including the electronic, glass, ceramic, and food pro fuel in a concentration up to 10%, reducing fuel Viscosity and cessing industries, and provide excellent reliability, pro improving emissions. longed life span, and minimal maintenance. Operating at a 0013 Methanol and its derivatives, e.g., DME, DMC, and relatively low temperature, the MTH process has a clear biodiesel, have many existing and potential uses. They can be advantage over reforming of natural gas and other hydrocar used, for example, as a substitute for gasoline and diesel fuel bons which must be conducted at above 600° C., because less in ICE-powered cars with only minor modifications to the energy is needed to heat methanol to the appropriate reaction existing engines and fuel systems. Methanol can also be used temperature. in fuel cells, for fuel cell vehicles (FCVs), which are consid 0018. The usefulness of methanol has led to development ered to be the best alternative to ICEs in the transportation of other reforming processes, for example, a process known field. DME is also a potential substitute for LNG and LPG for as oxidative steam reforming, which combines steam reform heating homes and in industrial uses. ing, partial oxidation of methanol, and novel catalyst systems. 0014 Methanol is also useful in reforming to hydrogen. In Oxidative steam reforming produces high purity hydrogen an effort to address the problems associated with hydrogen with Zero or trace amounts of CO, at high methanol conver storage and distribution, Suggestions have been made to use sion and temperatures as low as 23.0°C. It has the advantage liquids rich in hydrogen Such as gasoline or methanol as a of being, contrary to steam reforming, an exothermic reac Source of hydrogen in vehicles via an on-board reformer. It is tion, therefore minimizing energy consumption. There is also also considered that methanol is the safest of all materials autothermal reforming of methanol, which combines steam available for such hydrogen production. Further, because of reforming and partial oxidation of methanol in a specific ratio the high hydrogen content of liquid methanol, even compared and addresses any drawback of an exothermic reaction by to pure cryogenic hydrogen (98.8g of hydrogen in a liter of producing only enough energy to Sustain itself. Autothermal methanol at room temperature compared to 70.8 g. in liquid reforming is neither exothermic nor endothermic, and does US 2010/0193370 A1 Aug. 5, 2010
not require any external heating once the reaction temperature fractions as fuel. Compared to such fuels, methanol can is reached. Despite the aforementioned possibilities, hydro achieve higher power output and lower NO emissions gen fuel cells must use highly volatile and flammable hydro because of its lower flame temperature. Since methanol does gen or reformer systems. not contain sulfur, SO emissions are also eliminated. Opera 0019 U.S. Pat. No. 5.599,638 discloses a simple direct tion on methanol offers the same flexibility as on natural gas methanol fuel cell (DMFC) based on proton exchange mem and distillate fuels, and can be performed with existing tur branes (PEM) to address the disadvantages of hydrogen fuel bines, originally designed for natural gas or other fossil fuels, cells. In contrast to a hydrogen fuel cell, the DMFC is not after relatively easy modification. Methanol is also an attrac dependent on generation of hydrogen by processes such as tive fuel since fuel-grade methanol, with lower production electrolysis of water or reformation of natural gas or hydro cost than higher purity chemical-grade methanol, can be used carbon. The DMFC is also more cost effective because in turbines. Because the size and weight of a fuel cell is of less methanol, as a liquid fuel, does not require cooling at ambient importance in static applications than mobile applications, temperatures or costly high pressure infrastructure and can be various fuel cells other than PEM fuel cells and DMFC, such used with existing storage and dispensing units, unlike hydro as phosphoric acid, molten carbonate and Solid oxide fuel gen fuel, whose storage and distribution requires new infra cells (PAFC, MCFC, and SOFC, respectively), can also be structure. Further, methanol has a relatively high theoretical used. Volumetric energy density compared to other systems such as 0024. In addition to use as fuels, methanol and methanol conventional batteries and the H-PEM fuel cell. This is of derived chemicals have other significant applications in the great importance for Small portable applications (cellular chemical industry. Today, methanol is one of the most impor phones, laptop computers, etc.), for which Small size and tant feedstock in the chemical industry. Most of the 40 million weight of energy unit is desired. tons of annually produced methanol is used to manufacture a 0020. The DMFC offers numerous benefits in various large variety of chemical products and materials, including areas, including the transportation sector. By eliminating the basic chemicals such as formaldehyde, acetic acid, MTBE need for a methanol steam reformer, the DMFC significantly (although it is increasingly phased out in the U.S. for envi reduces the cost, complexity and weight of the vehicle, and ronmental reasons), as well as various polymers, paints, adhe improves fuel economy. A DMFC system is also comparable sives, construction materials, and others. Worldwide, almost in its simplicity to a direct hydrogen fuel cell, without the 70% of methanol is used to produce formaldehyde (38%), cumbersome problems of on-board hydrogen storage or methyl-tent-butyl ether (MTBE, 20%) and acetic acid (11%). hydrogen producing reformers. Because only water and CO Methanol is also a feedstock for chloromethanes, methy are emitted, emissions of other pollutants (e.g., NO PM, lamines, methyl methacrylate, and dimethyl terephthalate, SO, etc.) are eliminated. Direct methanol fuel cell vehicles among others. These chemical intermediates are then pro are expected to be virtually Zero emission vehicles (ZEV), cessed to manufacture products such as paints, resins, sili and use of methanol fuel cell vehicles offers to nearly elimi cones, adhesives, antifreeze, and plastics. Formaldehyde, nate air pollutants from vehicles in the long term. Further, produced in large quantities from methanol, is mainly used to unlike ICE vehicles, the emission profile is expected to prepare phenol-, urea- and melamine-formaldehyde and remain nearly unchanged over time. New membranes based polyacetal resins as well as butanediol and methylene bis(4- on hydrocarbon or hydrofluorocarbon materials with reduced phenyl isocyanate) (MDI; MDI foam is used as insulation in cost and crossover characteristics have been developed that refrigerators, doors, and in car dashboards and bumpers). allow room temperature efficiency of 34%. Formaldehyde resins are predominantly employed as an 0021. Further, in addition to such cation exchange-type adhesive in a wide variety of applications, e.g., manufacture fuel cells, anion exchange-type fuel cells using an anion of particle boards, plywood and otherwood panels. Examples conducting membrane and an anion-conducting binder (the of methanol-derived chemical products and materials are anions are usually hydroxide ions) are also studied for metha shown in FIG. 1. nol oxidation (US Patent Application Publication, US 2003/ 0025. In producing basic chemicals, raw material feed 004 9509 A1). It is known that in anion exchange-type fuel stock constitutes typically up to 60-70% of the manufacturing cells, overVoltage at the oxygen electrode is reduced, and the costs. The cost offeedstock therefore plays a significant eco improvement of energy efficiency is expected. Further, it is nomic role. Because of its lower cost, methanol is considered said that, when methanol is used as the fuel, methanol cross a potential feedstock for processes currently utilizing more over wherein methanol passes through the electrolyte mem expensive feedstocks such as ethylene and propylene, to pro brane between the electrodes is reduced. However, the duce chemicals including acetic acid, acetaldehyde, ethanol, hydroxide media is not compatible with carbon dioxide, ethylene glycol, styrene, and ethylbenzene, and various syn which readily produce bicarbonate and carbonate salts. thetic hydrocarbon products. For example, direct conversion 0022 Methanol as indicated provides a number of impor of methanol to ethanol can be achieved using a rhodium tant advantages as transportation fuel. Contrary to hydrogen, based catalyst, which has been found to promote the reductive methanol does not require any energy intensive procedures carbonylation of methanol to acetaldehyde with selectivity for pressurization or liquefaction. Because it is a liquid at close to 90%, and a ruthenium catalyst, which further reduces room temperature, it can be easily handled, stored, distributed acetaldehyde to ethanol. The possibility of producing ethyl and carried in vehicles. It can act as an ideal hydrogen carrier ene glycol via methanol oxidative coupling instead of the for fuel cell vehicles through on-board methanol reformers, usual process using ethylene as feedstock is also pursued, and and can be used directly in DMFC vehicles. significant advances for synthesizing ethylene glycol from 0023 Methanol is also an attractive source of fuel for dimethyl ether, obtained by methanol dehydration, have also static applications. For example, methanol can be used been made. directly as fuel in gas turbines to generate electric power. Gas 0026 Conversion of methanol to olefins such as ethylene turbines typically use natural gas or light petroleum distillate and propylene, also known as methanol to olefin (MTO) US 2010/0193370 A1 Aug. 5, 2010 technology, is particularly promising considering the high sively made from synthesis gas obtained from incomplete demand for olefin materials, especially in polyolefin produc combustion (or catalytic reforming) of fossil fuel, mainly tion. The MTO technology is presently a two-step process, in natural gas (methane) and coal. which natural gas is converted to methanol via Syn-gas and 0032 Methanol can also be made from renewable biom methanol is then transformed to olefin. It is considered that ass, but such methanol production also involves Syn-gas and methanol is first dehydrated to dimethyl ether (DME), which may not be energetically favorable and limited in terms of then reacts to form ethylene and/or propylene. Small amounts scale. As used herein, the term “biomass” includes any type of of butenes, higher olefins, alkanes, and aromatics are also plant or animal material, i.e., materials produced by a life formed. form, including wood and wood wastes, agricultural crops and their waste byproducts, municipal Solid waste, animal waste, aquatic plants, and algae. The method of transforming -H2O -H2O 2 CH3OH CH3OCH3 -- biomass to methanol is similar to the method of producing +HO methanol from coal, and requires gasification of biomass to HC=CH & H.C=CH-CH Syn-gas, followed by methanol synthesis by the same pro cesses used with fossil fuel. Use of biomass also presents Ethylene & Propylene other disadvantages, such as low energy density and high cost of collecting and transporting bulky biomass. Although 0027 Various catalysts, e.g., synthetic aluminosilicate recent improvements involving the use of “biocrude.” black catalysts, such as ZSM-5 (a zeolite developed by Mobil), liquid obtained from fast pyrolysis of biomass, is somewhat silicoaluminophosphate (SAPO) molecular sieves such as promising, more development is needed for commercial SAPO-34 and SAPO-17 (UOP), as well as bi-functional sup application of biocrude. Even paper and pulp industry wastes ported acid-base catalysts such as tungsten oxide over alu can be converted to syngas for methanol production. mina (WO/Al2O), have been found to be active in convert 0033. The presently existing method of producing metha ing methanol to ethylene and propylene at a temperature nol involves Syn-gas. Syn-gas is a mixture of hydrogen, car between 250 and 350° C. The type and amount of the end bon monoxide and carbon dioxide, and produces methanol product depend on the type of the catalyst and the MTO over a heterogeneous catalyst according to the following process used. Depending on the operating conditions, the equations: weight ratio of propylene to ethylene can be modified CO+2H2 CH3OH AH-98 -21.7 kcal/mol between about 0.77 and 1.33, allowing considerable flexibil ity. For example, when using SAPO-34 according to an MTO CO+3H2 CHOH--H2O AH-98 -9.8 kcal/ process developed by UOP and Norsk Hydro, methanol is mol converted to ethylene and propylene at more than 80% selec CO+H,-CO+HO AH-11.9 kcal/mol tivity, and also to butene, a valuable starting material for a number of products, at about 10%. While using an MTO 0034. The first two reactions are exothermic with heat of process developed by Lurgi with ZSM-5 catalysts, mostly reaction equal to -21.7 kcalmol' and -9.8 kcalmol', propylene is produced at yields above 70%. A process devel respectively, and resultina decrease in Volume. Conversion to oped by ExxonMobil, with ZSM-5 catalyst, produces hydro methanol is favored by increasing the pressure and decreasing carbons in the gasoline and/or distillate range at selectivity the temperature according to Le Chatelier's principle. The greater than 95%. third equation describes the endothermic reverse water gas 0028. There is also a methanol to gasoline (MTG) process, shift reaction (RWGSR). Carbon monoxide produced in the in which medium-pore Zeolites with considerable acidity, third reaction can further react with hydrogen to produce e.g., ZSM-5, are used as catalysts. In this process, methanol is methanol. The second reaction is simply the sum of the first first dehydrated to an equilibrium mixture of dimethyl ether, and the third reactions. Each of these reactions is reversible, methanol and water over a catalyst, and this mixture is then and is therefore limited by thermodynamic equilibrium under converted to light olefins, primarily ethylene and propylene. the reaction conditions, e.g., temperature, pressure and com The light olefins can undergo further transformations to position of the Syn-gas. higher olefins, C-C alkanes, and Co-Co aromatics such as 0035 Synthesis gas for methanol production can be toluene, Xylenes, and trimethylbenzene. obtained by reforming or partial oxidation of any carbon 0029. With decreasing oil and gas reserves, it is inevitable aceous material, such as coal, coke, natural gas, petroleum, that synthetic hydrocarbons would play a major role. Thus, heavy oil, and asphalt. The composition of syn-gas is gener methanol-based synthetic hydrocarbons and chemicals avail ally characterized by the stoichiometric number S. corre able through MTG and MTO processes will assume increas sponding to the equation shown below. ing importance in replacing oil and gas-based materials. The listed uses of methanol is only illustrative and not limiting. 0030 Methanol can also be used as a source of single cell S = (moles H2 - moles CO2) proteins. A single cell protein (SCP) refers to a protein pro T (moles CO + moles CO2) duced by a microorganism, which degrades hydrocarbon Sub strates while gaining energy. The protein content depends on Ideally, S should be equal to or slightly above 2. A value above the type of microorganism, e.g., bacteria, yeast, mold, etc. 2 indicates excess hydrogen, while a value below 2 indicates The SCP has many uses, including uses as food and animal relative hydrogen deficiency. Reforming offeedstock having feed. a higher H/C ratio, such as propane, butane or naphthas, leads 0031 Considering the numerous uses of methanol, it is to S values in the vicinity of 2, ideal for conversion to metha clearly desirable to have improved and efficient methods of nol. When coal or methane is used, however, additional treat producing methanol. Currently, methanol is almost exclu ment is required to obtain an optimal S value. Synthesis gas US 2010/0193370 A1 Aug. 5, 2010
from coal requires treatment to avoid formation of undesired aldhyde and methanol being formed in only smaller amounts. byproducts. Steam reforming of methaneyields Syn-gas with Direct electrochemical reduction of CO into methanol under a stoichiometric number of 2.8 to 3.0, and requires lowering pressure also provides methyl formate. Catalytic hydrogena the S value closer to 2 by adding CO or using excess hydro tion of carbon dioxide using heterogeneous catalysts provides gen in some other process such as ammonia synthesis. How methanol together with water as well as formic acid and ever, natural gas is still the preferred feedstock for methanol formaldehyde. As the generation of needed hydrogen is production because it offers high hydrogen content and, addi highly energy consuming, the production of methanol with tionally, the lowest energy consumption, capital investment equimolar amount of water as well as other side products and operating costs. Natural gas also contains fewer impuri from carbon dioxide is not practical. No efficient ways for the ties Such as Sulfur, halogenated compounds, and metals which selective high yield, high selectivity economical conversion may poison the catalysts used in the process. of carbon dioxide to methanol is presently known. The high 0036. The existing processes invariably employ extremely selectivity laboratory reduction of carbon dioxide to metha active and selective copper and zinc-based catalysts, differing nol with complex metal hydrides, such as lithium aluminum only in the reactor design and catalyst arrangement. Because hydride is extremely costly and therefore not suited for the only part of syn-gas is converted to methanol after passing bulk production of methanol. over the catalyst, the remaining Syn-gas is recycled after 0040 Attempts have been made to chemically convert separation of methanol and water. There is also a more CO to methanol and Subsequently to hydrocarbons by cata recently developed liquid phase process for methanol produc lytic or electrochemical hydrogenation. Catalysts based on tion, during which Syn-gas is bubbled into liquid. Although metals and their oxides, in particular copper and Zinc, have the existing processes have methanol selectivity greater than been developed for this process. These catalysts are unexpect 99% and energy efficiency above 70%, crude methanol leav edly similar to the ones currently used for the conventional ing the reactor still contains water and other impurities. Such methanol production via Syn-gas. It is now understood that as dissolved gas (e.g., methane, CO, and CO), dimethyl methanol is most probably formed almost exclusively by ether, methyl formate, acetone, higher alcohols (ethanol, pro hydrogenation of CO contained in Syn-gas on the Surface of panol, butanol), and long-chain hydrocarbons. Commer the catalyst. To be converted to methanol, CO present in the cially, methanol is available in three grades of purity: fuel Syn-gas first undergoes a water gas shift reaction to form CO grade, 'A' grade, generally used as a solvent, and 'AA' or and H2, and the CO, then reacts with hydrogen to produce chemical grade. Chemical grade has the highest purity with a methanol. One of the limiting factors for large scale use of methanol content exceeding 99.85% and is the standard gen such methanol conversion process is the availability of the erally observed in the industry for methanol production. The feedstock, i.e., CO, and H. While CO, can be obtained rela Syn-gas generation and purification steps are critical in the tively easily in large amounts from various industrial existing processes, and the end result would largely depend exhausts, hydrogen is mainly produced from non-renewable on the nature and purity of the feedstock. To achieve the fossil fuel-based syn-gas and therefore has limited availabil desired level of purity, methanol produced by the existing ity. Further, generation of hydrogen from fossil fuels has a processes is usually purified by sufficient distillation. Another high energy requirement. major disadvantage of the existing process for producing 0041. Other methods for hydrogen production from fossil methanol through syn-gas is the energy requirement of the fuel have been investigated, including the “Carnol’ process, first highly endothermic steam reforming step. The process is in which thermal decomposition of methane produces hydro also inefficient because it involves transformation of methane gen and solid carbon. The generated hydrogen is then reacted in an oxidative reaction to carbon monoxide (and some CO). with CO to produce methanol. This process is advantageous which in turn must be reduced to methanol. over methane steam reforming for requiring relatively less 0037. It is clearly desirable and maybe advantageous to energy, about 9 kcal for producing one mole of hydrogen, and produce methanol without first producing Syn-gas. It would for producing a byproduct that can be more easily handled, be further advantageous to use an abundant, practically stored and used, compared to CO emissions generated by unlimited resource Such as carbon dioxide as the carbon methane steam reforming or partial oxidation. However, the source to produce methanol. For example, U.S. Pat. No. thermal decomposition of methane requires heating it to tem 5,928,806, the entire content of which is incorporated herein peratures of above 800° C. and gives only relatively low yield by reference thereto, discloses production of methanol, and of hydrogen. The process, in any case, requires substantial related oxygenates and hydrocarbons, based on a carbon development for commercial application. dioxide-based regenerative fuel cell concept. 0042 U.S. Publication No. 2006/0235091 describes that 0038. When hydrocarbons are burned they produce car carbon dioxide can be used in the dry catalytic reforming of bon dioxide and water. It is clearly of great significance, if this methane, if natural gas is available, producing carbon mon process can be reversed and an efficient and economic process oxide and hydrogen to be used to produce methanol. can be found to produce methanol from carbon dioxide and 0043 A publication in 1991 also report that the electro water to be subsequently used for energy storage, fuels and chemical reduction of carbon dioxide in methanol solution production of synthetic hydrocarbons. In plant photosynthe under pressure was found to provide a high yield of methyl sis, carbon dioxide is captured from the air and converted with formate. water and Solar energy into new plant life. Conversion of plant 0044) The methyl formate can be subsequently hydroge life into fossil fuel, however, is a very long process. Thus, it it natively converted exclusively to methanol. Formic acid can is highly desirable to develop a process for chemical recy be used as the hydrogen source for the reduction of methyl cling carbon dioxide to produce hydrocarbons in a short, formate to methanol over noble metal catalysts. commercially feasible time scale. 0045. Otherwise, hydrogen used in catalytic hydrogena 0039 Carbon dioxide is known to be photochemically or tion can be obtained from any Suitable source, such as elec electrochemically readily reduced to formic acid with form trolysis of water, using any suitable method and Source of US 2010/0193370 A1 Aug. 5, 2010
energy, e.g., atomic, Solar, wind, geothermal, etc. Photolytic, may also be treated by subjecting the adsorbent to sufficient thermal, enzymatic, and other means of cleavage of water to reduced pressure to release the adsorbed carbon dioxide. hydrogen is also possible. 0053. The electrical energy for the electrochemical reduc 0046. In the above-described processes, a hydrogen ing of carbon dioxide can come from a conventional energy source must be added to the reaction mixture for conversion to Source, including nuclear and alternatives (hydroelectric, methanol. If methanol could be produced on a large scale wind, Solar power, geothermal, etc.). directly from electrochemical reduction of carbon dioxide, 0054 Also, oxygen produced at the anode can be used for without the extra step of adding a hydrogen Source, such a the efficient combustion of fossil fuels in power plants exclu process would be advantageous considering the abundant sively to produce CO exhausts for capture and recycling. Supply of carbon dioxide in the atmosphere and in industrial This can replace the air sources commonly used with the exhausts of fossil fuel power burning power plants and resulting exhausts containing only CO, so that the CO does cement plants. It would at the same time also mitigate green not have to be adsorbed from the exhaust gas before being house effect that is causing the global climate change (i.e., supplied to the cell. global warming). The present invention now provides such a process to obtain these benefits. BRIEF DESCRIPTION OF THE DRAWINGS 0055. The benefits of the invention will become more evi SUMMARY OF THE INVENTION dent from review of the following detailed description of 0047. The invention relates to various embodiments of an illustrative embodiments and the accompanying drawings, environmentally beneficial method for producing methanol wherein: by reductive conversion of an available source of carbon 0056 FIG. 1 shows known examples of methanol-derived dioxide including flue gases of fossil fuel burning power chemical products and materials; and plants, industrial exhaust gases or the atmosphere itself. The 0057 FIG. 2 schematically illustrates the METHANOL method includes electrochemically reducing the carbon diox ECONOMY process. ide in a divided electrochemical cell that includes an anode in one cell compartment and a metal cathode electrode in DETAILED DESCRIPTION OF THE PREFERRED another cell compartment that also contains an aqueous solu EMBODIMENTS tion or aqueous methanolic solution and an electrolyte of one 0058. The present invention relates to the simple, efficient, or more alkyl ammonium halides, alkali or ammonium car and economical conversion of carbon dioxide from flue gases bonates and bicarbonates or ionic liquids or combinations of fossil fuel burning power plants, industrial exhaust gases, thereof to produce therein a reaction mixture containing car carbon dioxide accompanying natural gas, carbon dioxide bon monoxide and hydrogen which can be subsequently used accompanying steam from geothermal wells or from the to produce methanol while also producing oxygen in the cell atmosphere itself to methanol, with Subsequent application at the anode. for energy storage and transportation fuels, conversion to 0048. The alkyl ammonium halides include multi-alkyl synthetic hydrocarbons and its products. The carbon dioxide ammonium halides and preferably tetrabutylammonium to methanol conversion is a better alternative to sequestration halides. In another embodiment, the tetrabutylammonium making it a renewable general carbon source for fuels, Syn halide is selected from the group consisting of tetrabutylam thetic hydrocarbons and their products. The use of this pro monium bromide, tetrabutylammonium chloride, tetrabuty cess of converting carbon dioxide to methanol and its prod lammonium iodide or mixtures thereof. The alkali carbonates ucts will also lead to a significant reduction of carbon dioxide, include bicarbonates such as Sodium or potassium bicarbon a major greenhouse gas, in the atmosphere thus mitigating ates and the like. global warming. 0049. In another embodiment, the method comprises pro 0059. In one embodiment, the method includes electro viding a divided electrochemical cell that also contains an chemically reducing the carbon dioxide in a divided electro aqueous solution, and an anion-conducting membrane firmly chemical cell that includes an anode in one cell compartment sandwiched between the anode and cathode, separating the and a metal cathode electrode in another cell compartment anode and the cathode compartments. that also contains an aqueous Solution or aqueous methanolic 0050. While the cathode electrode may be chosen from Solution and an electrolyte of one or more alkyl ammonium any suitable metal electrode, such as Cu, Au, Ag, Zn, Pd, Ga. halides, alkali or ammonium carbonates and bicarbonates or Ni, Hg, In, Sn, Cd, T1, Pb, and Pt, preferably the metal elec ionic liquids or combinations thereof to produce therein a trode is a gold electrode. The metal electrode acts as a catalyst reaction mixture containing carbon monoxide and hydrogen for the electrochemical reduction. which can be Subsequently used to produce methanol while 0051. In the embodiment, the electrochemical reduction also producing oxygen in the cell at the anode. includes applying a Voltage of about -1.5 to -4V with respect 0060. In another embodiment, the method comprises pro to a Ag/AgCl electrode to produce the reaction. viding a divided electrochemical cell comprising an anode in 0052 Advantageously, the carbon dioxide used in the a first cell compartment, a metal cathode electrode in a second reaction is obtained from an exhaust stream from fossil fuel cell compartment that also contains an aqueous solution, and burning power or industrial plants, from geothermal or natu an anion-conducting membrane between the anode and cath ral gas wells. The available carbon dioxide, however, may ode. The anion conducting membrane is permeable to anions also be obtained from the atmosphere by absorbing atmo as, for example, hydroxide, bicarbonate or carbonate ions. A spheric carbon dioxide onto a suitable adsorbent followed by Suitable membrane is an anion-conducting polymer electro treating the adsorbent to release the adsorbed carbon dioxide lyte based on polymeric amines. therefrom. In this embodiment, the adsorbent is treated by 0061 Carbon dioxide is preferably obtained from concen sufficient heating to release the adsorbed carbon dioxide, or trated point sources of its generation prior to its release into US 2010/0193370 A1 Aug. 5, 2010
the atmosphere. Carbon dioxide can, however, also be The specific conditions for the above-described chemical obtained by separating atmospheric carbon dioxide with a reactions are generally known to skilled chemists and opti suitable adsorbent followed by desorption treatment to mum conditions can be readily established for the reactions. release the adsorbed carbon dioxide therefrom, as disclosed Typical yields are about 60 to 100%, based on the amount of in PCT Application No. WO 2008/021700. This can be CO, preferably about 75 to 90%, and more preferably about achieved by heating to release the adsorbed carbon dioxide, 85 to 95%. At a proper voltage, i.e. about -1.5 to -4V with by treating it under reduced pressure or by a suitable combi respect to an Ag"/AgCl electrode, a ratio of about 1:2 of CO nation of both. Alternatively, by recycling the oxygen pro and H2 can be produced with good columbic efficiency at the duced at the anode to a power plant, the efficient combustion cathode. of fossil fuels can be achieved to exclusively to produce CO, 0068. The electrochemical reduction of CO can also be exhausts for capture and recycling to the cell. The replace achieved efficiently using KHCO as the electrolyte in aque ment of air sources with exhausts containing only CO avoids ous medium. CO is readily reduced in the aqueous medium the need to separate CO2 from nitrogen and other gases before over gold electrode to an optimal 1:2 (CO to H-) ratio at the being Supplied to the cell. cathode at -3.2V. The columbic efficiences are quite high 0062 Methanol produced according to the discussed pro reaching 100%. Pure oxygen is produced at the anode. The cesses can be used for any purpose, Such as for energy storage electricity needed for the electrochemical reduction can come and transportation, as a fuel in internal combustion engines or from any source including nuclear or alternative energy (hy fuel cells, to produce related fuels (dimethyl ether, by dehy dro, wind, Solar, geothermal, etc.). dration), dimethyl carbonate (by oxidative carbonylation), to 0069. The present invention advantageously produces produce ethylene, propylene, higher olefins, synthetic hydro methanol without the need of adding extra reactants, such as carbons and all their derived products including and not lim a hydrogen Source. There is also no need to separate the ited to single cell proteins. product mixture in a Subsequent treatment step, thereby 0063 High concentration carbon dioxide sources are streamlining methanol production. those frequently accompanying natural gas in amounts of 5 to 0070 The use of carbon dioxide based methanol is highly 50%, those from flue gases of fossil fuel (coal, natural gas, oil, desirable as it can mitigate and eventually replace the world's etc.) burning powerplants, exhaust of cement plants and other reliance on fossil fuels. In addition, the reduction in carbon dioxide emissions as well as the removal of excess carbon industrial sources. Certain geothermal steam also contains dioxide from the atmosphere will assist in reducing global significant amounts of CO. warming and restoring atmospheric conditions to a preindus 0064. It has now been discovered that the use of electro trial levels, thus preserving the planet's climate for future chemical reduction of carbon dioxide (CO), tailored over generations. certain cathode electrocatalysts produces carbon monoxide (0071 CO emissions from fossil fuel burning power (CO) and hydrogen gas (H) in a high yielding ratio of plants and varied industries including geothermal wells can approximately 1:2. The ratio can be between 1:2 and 1:2.1 be captured on-site. Separation of CO2 from Such exhausts is with 1:2.05 being optimal regarding efficiency and reactant well-developed. The capture and use of existing atmospheric cost. Electrochemical reduction of CO on metal electrodes CO allows chemical recycling of CO as a renewable and such as Cu, Au, Ag, Zn, Pd, Ga, Ni, Hg, In, Sn, Cd, T1, Pb, and unlimited source of carbon. CO, absorption facilities can be Pt can give either methyl formate or CO using a variety of placed proximate to a hydrogen production site to enable electrolytes and solvents (Y. Hori, H. Wakabe, T. Tsuamoto subsequent methanol synthesis. When the processes of the and O. Koga, Electrochimica Acta, 1994, 39, 1833-1839). invention utilize carbon dioxide from the atmosphere, the The gold (Au) electrode has been found particularly effective carbon dioxide can be separated and absorbed by using vari for the production of CO. ous processes as described in published PCT Application No. 0065. It has further been discovered that the electrochemi WO 2008/021700 and U.S. Pat. No. 7,378,561 or can be cal reduction of CO using nobel metal, preferentially a gold recycled chemically as described in U.S. Pat. Nos. 7,605,293 electrode as a catalyst in aqueous methanol (or in water) with and 7,608,743. Although the CO content in the atmosphere is tetrabutylammonium halides and alkali or ammonium car low (only 0.037%), the atmosphere offers an abundant and bonates and bicarbonates or other ionic liquids as electrolytes unlimited Supply because CO is recycled. For using atmo not only gives CO but also H at the cathode, while producing spheric carbon dioxide efficiently, CO absorption facilities oxygen gas (O) at the anode. Organic ionic liquids based on are needed. This can be addressed by using efficient CO imidazole and related derivatives with bicarbonate and absorbents such as polyethyleneimines, polyvinylpyridines, related counteranions can also serve as good electrolytes for polyvinylpyrroles, etc., on Suitable solid carriers (e.g., active CO, reduction. carbon, polymer, silica or alumina), which allow absorbtion 0066 Suitable tetrabutylammonium halides for use in the of even the low concentration of atmospheric CO, CO, can present invention include tetrabutylammonium bromide, tet also be captured using basic absorbents such as calcium rabutylammonium chloride, and tetrabutylammonium hydroxide (Ca(OH)) and potassium hydroxide (KOH), iodide. Tetraalkyl ammonium salts are known to promote one which react with CO to form calcium carbonate (CaCO) electron reduction of CO. and potassium carbonate (KCO), respectively. CO absorp CO+2H2O->CO+2H (at the cathode) and 3/2O (at tion is an exothermic reaction, which liberates heat, and is the anode) readily achieved by contacting CO with an appropriate base. After capture, CO, is recovered from the absorbent by des 0067. The CO and H produced at the cathode are subse orption, through heating, vacuum (or reduced pressure) or quently reacted over Cu and Ni based catalysts to produce electrochemical treatment. Calcium carbonate, for example, high yields of methanol (CHOH). is thermally calcinated to release carbon dioxide. As desorp tion is an endothermic, energy-demanding step, the appropri US 2010/0193370 A1 Aug. 5, 2010
ate treatment can be chosen to optimize absorption and des 0077. The improved and efficient selective conversion of orption with the lowest possible energy input. Thus, CO can carbon dioxide, which can be from atmospheric or industrial be recycled by operation of absorbing-desorbing columns in exhaust sources, to methanol according to the present inven convenient cycles with modest heating and/or under reduced tion also provides the needed raw material for what the inven pressure to cause desorption of CO to take place. tors have termed the METHANOL ECONOMY process (see 0072. When methanol, methanol-derived fuels or syn Beyond Oil and Gas: The Methanol Economy, G. A. Olah, A. thetic hydrocarbons are combusted (oxidatively used), they Goeppert and G. K. S. Prakash, 2" Edition, Wiley-VCH, release CO and water, thus providing the basis methanol Weinheim, 2009). This allows convenient storage and trans cycle, the artificial version of the natural recylcing of CO, port of energy in a liquid product that can be used as a fuel in through photosynthesis. In contrast to the nonrenewable fos internal combustion engines or in fuel cells and as a starting sil fuel sources such as oil, gas, and coal, recycling carbon material for synthetic hydrocarbons and their varied products. dioxide from industrial and natural Sources to produce metha The METHANOL ECONOMY process is based on the effi nol not only addresses the problem of diminishing fossil fuel cient direct conversion of still available natural gas resources resources, but also helps alleviate global warming due to to methanol or dimethyl ether, as disclosed in U.S. Pat. Nos. greenhouse effect. 7,605,293 and 7,608,743, and US Publication No. 2006/ 0073. The effective electrochemical hydrogenative recy 0235088, as well as the presently disclosed reductive chemi cling of carbon dioxide disclosed herein provides new meth cal conversion of carbon dioxide. The concept of the ods of producing methanol in an improved, efficient, and METHANOL ECONOMY process presents significant environmentally beneficial way, while mitigating CO caused advantages and possibilities. In the METHANOL climate change (global warming). The use of methanol as a ECONOMY process, methanol is used as (1) convenient energy storage and transportation material eliminates many energy storage medium, which allows convenient and safe difficulties of using hydrogen for Such purposes. The safety storage and handling; (2) readily transported and dispensed and versatility of methanol makes the disclosed recycling of fuel, including for methanol fuel cells; and (3) feedstock for carbon dioxide further desirable. synthetic hydrocarbons and their products currently obtained 0074 As known in the art, methanol can be easily treated from oil and gas resources, including polymers and even to produce varied derived compounds including dimethyl single cell proteins, which can be used for animal feed or ether, produced by dehydration of methanol, and dimethyl human consumption. The environmental benefits obtained by carbonate, produced by reaction of the methanol by oxidative disclosed chemical recycling of carbon dioxide results in carbonylation. Methanol and methanol-derived compounds, mitigating the global warming to ensure the well being of e.g., DME and DMC as oxygenated additives, can be blended future generations. with gasoline and used in internal combustion engines with 0078. As methanol is readily dehydrated to dimethyl ether, only minor modifications. For example, methanol can be the disclosed conversion of carbon dioxide to methanol is also added to gasoline up to 85% by volume to prepare M85 fuel. adaptable to produce dimethyl ether for fuel and chemical Methanol can also be used to generate electricity in fuel cells, applications as previously noted. by either first catalytically reforming methanol to H and CO 007.9 The disclosed new efficient production of methanol or by reacting methanol directly with air in a direct methanol from industrial or natural carbon dioxide sources, or even fuel cell (DMFC). DMFC greatly simplifies the fuel cell from the air itself, provides the needed raw material for technology and makes it readily available to a wide range of replacing the diminishing fossil fuel through the METHA applications, including portable mobile electronic devices NOL ECONOMY process. The conversion of carbon dioxide and electricity generators. to methanol necessitates significant energy, which can be, 0075. In addition to being a conveniently storable energy however, provided by any energy source including offpeak source and fuel, methanol and methanol-derived DME and electric power of fossil fuel (e.g., coal) burning power plants, DMC are useful starting materials for various chemicals such atomic energy or any alternative energy sources (Solar, wind, as formaldehyde, acetic acid, and a number of other products geothermal, hydro, etc.). The reduction of CO to methanol including polymers, paints, adhesives, construction materi allows storage and transportation of energy in a convenient als, synthetic chemicals, pharmaceuticals, and single cell pro liquid product (i.e., methanol) more convenient, economical teins. and safe than Volatile hydrogen gas. Methanol and/or dim 0076 Methanol and/or dimethyl ether can also be conve ethyl ether are efficient fuels in internal combustion engines niently converted in a single catalytic step to ethylene and/or or in direct oxidation methanol fuel cells (DMFC as well as propylene (e.g., in a methanol to olefin or “MTO” process), raw materials for olefins, synthetic hydrocarbons and varied the building blocks for producing synthetic hydrocarbons and products). The present invention greatly extends the scope of their products. This means that the hydrocarbon fuels and the utilization of carbon dioxide for the production of metha products currently derived from oil and natural gas can be nol and/or dimethyl ether from natural or industrial sources, obtained from methanol, which itself can advantageously be even from the air itself. obtained from simple chemical recycling of atmospheric or industrial CO sources. Another utilization of methanol is its EXAMPLES ready conversion to ethanol via hydration of derived ethylene. 0080. The following examples illustrate the most pre Many further applications are known and can be applied to ferred embodiments of the invention without limiting it. carbon dioxide derived methanol. It should be emphasized that there is no preference for any particular energy source Example 1 needed for producing methanol. All sources, including alter native sources and atomic energy can be used. Energy once I0081. In a divided electrochemical cell, using tetrabuty produced must be, however, stored and transported, for which lammonium halides, preferentially tetrabutylammonium bro methanol is well suited. mide as the electrolyte over gold electrode (cathode) in aque US 2010/0193370 A1 Aug. 5, 2010
ous methanol medium at either -1.5V or -4V vs. Ag/AgCl 2. The method of claim 1 wherein the carbon monoxide and reference electrode, CO is reduced and water is electrolyzed hydrogen gas are obtained in the reaction mixture in a ratio of to an optimal 1:2 mixture of CO and H at the cathode. Pure at least about 1:2 or with excess amounts of hydrogen gas, and oxygen as well as some bromine is produced at the anode. without adding hydrogen from outside of the cell. 3. The method of claim 1, wherein the carbon monoxide Example 2 and hydrogen gas are present in the reaction mixture in a ratio 0082 In a divided electrochemical cell, using, aqueous of 1:2 to 1:2.1. 0.1M KHCO, as the electrolyte CO, is reduced at the gold 4. The method of claim 1, wherein the electrolyte com cathode at -3.2V vs. Ag/AgCl reference electrode CO is prises methanol or water. reduced and water is electrolyzed to an optimal 1:2 mixture of 5. The method of claim 1, wherein the metal cathode elec CO and H suitable for methanol synthesis. The total faradaic trode is a Cu, Au, Ag, Zn, Pd, Ga, Ni, Hg, In, Sn, Cd, T1, Pb or efficiences for CO and H production add up to 100%. Pure Pt electrode. oxygen is produced at the anode. Organic ionic liquids based 6. The method of claim 5, wherein the metal cathode elec on imidazole and related derivatives with bicarbonate counter trode is a gold electrode. ions also serve as good electrolytes. 7. The method of claim 1, wherein the electrochemical reduction includes applying a Voltage of from -1.5 to -4V Example 3 with respect to a Ag/AgCl reference electrode. 0083. In a divided electrochemical cell in which anode cell 8. The method of claim 1, wherein the existing source is an compartment and cathode cell compartment is separated by a exhaust stream from a fossil fuel burning power or industrial membrane electrode assembly (MEA) consisting of anion plant, from a source accompanying natural gas or from geo conducting (such as OH , HCO, or CO) polymeric thermal wells and wherein the carbon dioxide is obtained membrane firmly sandwiched between catalyst coated cath from Such existing source. ode (preferably gold deposited on conducting Toray carbon 9. The method of claim 1, wherein the existing source is the paper or cloth) and catalyst coated anode (Pt deposited on atmosphere and which further comprises obtaining the car conducting Toray carbon paper or cloth), at a potential of bon dioxide from Such existing source by absorbing atmo ~-3.0 V vs Ag/AgCl reference electrode, CO, is reduced and spheric carbon dioxide onto a suitable adsorbent followed by water is electrolyzed at the cathode side to an optimal 1:2 treating the adsorbent to release the adsorbed carbon dioxide mixture of CO and H suitable for methanol production. Pure therefrom. oxygen is produced at the anode. The use of such membrane 10. The method of claim 9, wherein the adsorbent is treated electrode assembly (MEA) separator ensures facile separa by sufficient heating or by subjecting the adsorbent to suffi tion of cathode and anode products. cient reduced pressure to release the adsorbed carbon dioxide. What is claimed is: 11. The method of claim 1, wherein electrical energy for 1. An environmentally beneficial method of producing the electrochemical reduction of the carbon dioxide is pro methanol by recycling and reductive conversion of any avail vided from an energy source based on nuclear, hydroelectric, able source of carbon dioxide, which comprises: wind, geothermal or Solar power. providing a divided electrochemical cell comprising an 12. The method of claim 1, wherein the oxygen produced at anode in a first cell compartment, a metal cathode elec the anode is utilized for efficient combustion of fossil fuels in trode in a second cell compartment that also contains an power plants to exclusively produce clean CO exhausts for aqueous solution, and an anion-conducting membrane capture and recycling. firmly sandwiched between the anode and cathode: recycling carbon dioxide from an existing Source into the 13. The method of claim 12, wherein the CO, exhausts are second cell compartment; captured and recycled as as the source of CO for the cell. electrochemically reducing the recycled carbon dioxide 14. The method of claim 1, wherein the anion-conducting and Solution in the second cell compartment to produce membrane is sandwiched between the anode and cathode in a therein a reaction mixture containing carbon monoxide membrane electrode assembly. and hydrogen gas; and 15. The method of claim 1 wherein the membrane is an obtaining the carbon monoxide and hydrogen gas of the anion-conducting polymer electrolyte based on polymeric reaction mixture from the second cell compartment and amines. directly reacting the reaction mixture in the presence of 16. The method of claim 1 wherein the electrolyte com a catalyst to produce methanol while also producing prises an organic ionic liquids based on imidazole and related oxygen in the first cell compartment at the anode to derivatives with bicarbonate and related counter anions. benefit the environment by reducing atmospheric carbon dioxide. c c c c c