MULTICOMPONENT HETEROGENEOUS CATALYSTS FOR DIRECT CO2 HYDROGENATION TO METHANOL

Abstract

Mixed metal oxide catalysts capable of catalyzing hydrogenation of carbon dioxide to methanol reaction are disclosed, as well as a method for producing methanol from carbon dioxide and hydrogen. The mixed metal oxide catalysts include copper (Cu), and M.sup.1 and M.sup.2 oxides. M.sup.1 can be zinc (Zn), zirconium (Zr), or cerium (Ce), or any combination thereof, and M.sup.2 can be yttrium (Y), barium (Ba), rubidium (Rb), terbium (Tb), strontium (Sr), or molybdenum (Mo), or any combination thereof, with the proviso that M.sup.2 is not Y when the mixed metal oxide catalyst is [Cu/Zn/M.sup.2]0.sub.n or [Cu/Zr/M]0.sub.n, where n is determined by the oxidation states of the other elements.

Claims

1-20. (canceled)

21. A mixed metal oxide catalyst capable of producing methanol (CH.sub.3OH) from carbon dioxide (CO.sub.2) and hydrogen (H.sub.2), the mixed metal oxide catalyst comprising
[Cu.sub.aZn.sub.bZr.sub.cCe.sub.dMe.sup.2]O.sub.n where a is 25 to 80, b is 1 to 57, c is 1 to 30, d is 1 to 30, and e is 1 to 40, and thereof, and M.sup.2 is yttrium (Y), barium (Ba), rubidium (Rb), terbium (Tb), strontium (Sr), or molybdenum (Mo), or any combination thereof.

22. The mixed metal oxide catalyst of claim 21, wherein M.sup.2 is Ba.

23. The mixed metal oxide catalyst of claim 21, wherein M.sup.2 is Rb.

24. The mixed metal oxide catalyst of claim 21, wherein M.sup.2 is Tb.

25. The mixed metal oxide catalyst of claim 21, wherein M.sup.2 is Sr.

26. The mixed metal oxide catalyst of claim 21, wherein M.sup.2 is Mo.

27. The mixed metal oxide catalyst of claim 21, wherein the catalyst has been calcined for 2 to 6 hours at a temperature of 250 to 650 C.

28. The mixed metal oxide catalyst of claim 27, wherein the catalyst has been reduced for 2 to 3 hours at a temperature of 180 to 350 C.

29. The mixed metal oxide catalyst of claim 21, wherein the catalyst is capable of producing CH.sub.3OH from CO.sub.2 and H.sub.2 in a single pass.

30. A method of producing methanol (CH.sub.3OH) from carbon dioxide (CO.sub.2) and hydrogen (H.sub.2), the method comprising contacting a reactant gas stream that includes CO.sub.2 and H.sub.2 with a mixed metal oxide catalyst of claim 21 under conditions sufficient to produce a product gas stream comprising CH.sub.3OH from hydrogenation of the CO.sub.2.

31. The method of claim 30, wherein CH.sub.3OH is produced from the CO.sub.2 and H.sub.2 in a single pass.

32. The method of claim 32, wherein the reactant gas stream has a ratio of H.sub.2/CO.sub.2 of 1 to 5, preferably 3 to 5 and/or the reaction conditions include a temperature of 200 C. to 300 C., preferably, 220 C. to 260 C., a pressure of 1 bar to 100 bar, preferably 30 bar to 50 bar, and a gas hourly space velocity of 2,500 to 20,000 h.sup.1, preferably of 4,000 V to 6,000 V.

33. The mixed metal oxide catalyst of claim 21, wherein the average CuO particle size is from 10.5 nm to 11.4 nm.

34. The mixed metal oxide catalyst of claim 21, wherein the catalyst is [Cu.sub.aZn.sub.bZr.sub.cCe.sub.dY.sub.e]O.sub.n-where a is 25 to 80, b is 1 to 57, c is 1 to 30, d is 1 to 30, and e is 1 to 40.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a schematic of an embodiment of a system for producing methanol from CO.sub.2.

[0033] FIG. 2 shows X-ray Diffraction (XRD) patterns of fresh and used catalyst of the present invention with an atomic ratio of copper, zinc, zirconium, cerium and yttrium of 60:20:10:5:5.

[0034] FIG. 3 shows X-ray Diffraction (XRD) patterns of fresh and used catalyst of the present invention with an atomic ratio of copper, zinc, zirconium, cerium and lanthanum of 65:20:5:5:5.

[0035] FIG. 4 shows an X-ray Diffraction (XRD) pattern of the catalyst of the present invention with an atomic ratio of copper, zinc, zirconium, cerium and barium of 55:10:15:10:10.

[0036] FIG. 5 shows an X-ray Diffraction (XRD) pattern of the catalyst of the present invention with an atomic ratio of copper, zinc, zirconium, cerium and barium of 60:15:10:10:5.

[0037] FIG. 6 shows a graphical representation of the methanol yield over Cu/Zn/Zr/Ce/Y catalysts of the present invention as a function of time on stream (TOS) at 30 bar (3.0 MPa) and different temperature and GHSV.

[0038] FIG. 7 shows a graphical representation of the methanol yield over a 60% Cu/20% Zn/10% Zr/5% Ce/5% Y catalyst of the present invention as a function of TOS at 40 bar (4.0 MPa) and various gas hourly space velocities.

[0039] FIG. 8 shows a graphical representation of the methanol yield over Cu/Zn/Zr/Ce/La catalysts of the present invention as a function of TOS at 30 bar (3 MPa), different temperatures, and various gas hourly space velocities.

[0040] FIG. 9 shows a graphical representation of the methanol yield over 65% Cu/20% Zn/5% Zr/5% Ce/5% La catalyst of the present invention as a function of TOS at 40 bar (4 MPa) and different GHSV.

[0041] FIG. 10 shows a graphical representation of the methanol yield over Cu/Zn/Zr/Ce/Ba catalysts as a function of TOS at 30 bar (3 MPa) and different temperature and GHSV.

[0042] FIG. 11 shows a graphical representation of the methanol yield over 60% Cu/20% Zn/10% Zr/5% Ce/5% Ba catalyst of the present invention as a function of TOS at 40 bar (4.0 MPa) and different GHSV.

[0043] FIG. 12 shows a graphical representation of the methanol yield and carbon dioxide conversion Cu/Zn/Zr/Ce/Rb catalyst as a function of TOS at 40 bar (4.0 MPa) and different temperatures and GHSV.

[0044] FIG. 13 shows a graphical representation of the methanol yield and carbon dioxide conversion Cu/Zn/Zr/Ce/Tb catalyst as a function of TOS at 40 bar (4.0 MPa) and different temperatures and GHSV.

[0045] FIG. 14 shows a graphical representation of the methanol yield and carbon dioxide conversion Cu/Zn/Zr/Ce/Sr catalyst as a function of TOS at 40 bar (4.0 MPa) and different GHSVs.

[0046] FIG. 15 shows a graphical representation of the methanol yield over 55% Cu/20% Zn/10% Zr/5% Ce/5% Y/5% La catalyst of the present invention as a function of TOS at 40 bar (4.0 MPa), gas hourly space velocity of 5400 h.sup.1, and different temperatures.

DETAILED DESCRIPTION OF THE INVENTION

[0047] A discovery has been made that provides stable, highly active catalysts for the direct catalytic conversion of carbon dioxide to methanol in one pass via a hydrogenation reaction. The invention provides an elegant way to provide a cost-effective method to convert carbon dioxide (CO.sub.2) to methanol and to reduce greenhouse gas emissions while at the same time use a waste product (e.g., CO.sub.2) as an inexpensive and readily available feedstock. The methanol produced from this process can be free, or substantially free, of by-products other than carbon monoxide and water. The discovery is premised on the use of a catalyst that is resistant to water, while catalyzing the reverse water-gas shift reaction (See, reaction scheme (2)) and the production of methanol from carbon dioxide at higher yield at low temperatures. Thus, multi-step reactors are not necessary, thereby increasing the efficiency of the process. By way of example, the current invention provides a substantial improvement over current syngas technologies by providing a process to manufacture methanol without the use of expensive and inefficient equipment (e.g. a reformer that costs approximately 60% of the total methanol plant in current commercial processes). The current embodiments also provide a process to manufacture methanol with higher purity that reduces purification time and cost in comparison to that from the currently available routes. The catalysts of the present invention can be multicomponent heterogeneous mixed metal oxides prepared by gel oxalate co-precipitation. In particular, the discovery is premised on the use of metal oxides that promote storing and releasing of oxygen (e.g., Zn, Zr, Ce, or combinations thereof) in the catalyst in combination with other catalytic metals (e.g., Cu, Y, Ba, Rb, Tb, Sr, Mo, or combinations thereof). Specifically, the presence of the oxygen storage metal oxides in the current catalysts can promote the removal of water by CO in the water-gas shift reaction, stabilize the dispersion of copper, and store and release oxygen under oxidizing and reducing conditions. Thus, these metal oxides, preferably cerium oxide, can be employed in the current embodiments to help protect and stabilize the catalyst active sites for CO.sub.2 hydrogenation to methanol. The catalysts of this invention can also be stable for extended periods during use (e.g., time on stream).

[0048] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Mixed Metal Oxide Catalyst

[0049] The catalysts of the present invention are capable of producing methanol from carbon dioxide and hydrogen in a single pass. One or more of these catalysts can include a heterogeneous mixed metal oxide catalyst that can contain metals (e.g., metals in reduced form), metal compounds (e.g., metal oxides) or mixtures thereof (collectively metals) of Column 1 or 2 metals, transition metals, and lanthanides (atomic number 57-71) of the Periodic Table. The metals in the catalyst can exist in one or more oxidation states. A non-limiting example of a Column 1 and 2 metals includes rubidium (Rb), barium (Ba) and strontium (Sr). Non-limiting examples of transition metals include ytterbium (Y), titanium (Ti), zirconium (Zr), molybdenum (Mo), tungsten (W), copper (Cu), silver (Ag), and zinc (Zn). Non-limiting examples of the lower lanthanides include lanthanum (La), cerium (Ce) and terbium (Tb). Preferably, the mixed metal oxide catalyst includes copper, zinc, zirconium, cerium, and M, where M is yttrium, barium, rubidium, terbium, strontium, or molybdenum. In one particular instance, the mixed metal oxide catalyst includes copper, zinc, zirconium, cerium, and yttrium. The mixed metal oxide catalyst can include copper (Cu), M.sup.1 oxides, and M.sup.2 oxides, where M.sup.1 can be Zn, Zr, Ce, or any combination thereof, and M.sup.2 is Y, Ba, Rb, Tb, Sr, or Mo, or any combination thereof, with the proviso that M.sup.2 is not Y when the mixed metal oxide catalyst is [Cu/Zn/M.sup.2]O.sub.n or [Cu/Zr/M.sup.2]O.sub.n, where n is determined by the oxidation states of the other elements. The catalyst can be [Cu/Zn/Zr/Ce/M.sup.2]O.sub.n mixed metal oxide having a general formula of: [Cu.sub.aZn.sub.bZr.sub.cCe.sub.dM.sub.e.sup.2]O.sub.n where a is 25 to 80, 30 to 70, or 40 to 60, or any range or number there between (e.g., 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80), b is 1 to 57, 5 to 50, 10 to 40, 15 to 30, or any range or number there between (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, or 57), c is 1 to 30, 5 to 25, or 10 to 20 or any number there between (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30), d is 1 to 30, (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30), and e is 1 to 40, 5 to 30, 10 to 20 or any number there between (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40). M.sup.2 of the mixed metal oxide catalyst can be Y, Ba, Rb, Tb, Sr, Mo or a mixture thereof. In some aspects the catalyst is a [Cu/Zn/M.sup.2]O.sub.n mixed metal oxide having a general formula of [Cu.sub.aZn.sub.bM.sub.c.sup.2]O.sub.n, M.sup.2 is Ba, Rb, Tb, Sr, or Mo, or any combination thereof, where a is 25 to 80, b is 1 to 57, and c is 1 to 30. In another aspect of the invention, the mixed metal catalyst can be a [Cu.sub.aZr.sub.bM.sub.c.sup.2]O.sub.n metal oxide having the general formula of [Cu.sub.aZr.sub.bM.sub.c.sup.2]O.sub.n where a is 25 to 80, b is 1 to 57, and c is 1 to 30. The catalyst can have an atomic ratio of metals ranging from about 1 to about 90. For example, in one aspect, the atomic ratio of a Cu/Zn/Zr/Ce/Y catalyst can range from about 5-80:5-30:5-25:1-20:1-20, or 25-80:1-57:1-30:1-30:1-40, preferably about 55:10:15:10:10, about 60:20:10:5:5, about 60:15:10:5:10, about 60:15:10:10:5, and about 65:20:5:5:5. In another aspect, the atomic ratio of a Cu/Zn/Zr/Ce/La catalyst ranges from about 10-80:5-30:1-20:1-20:1-20, or 25-80:1-57:1-30:1-30:1-40, preferably about 45:20:15:10:10, about 60:10:10:10:10, and about 65:20:5:5:5. In another aspect, the atomic ratio of a Cu/Zn/Zr/Ce/Y/La catalyst ranges about 5-80:5-30:5-20:1-15:1-15:1-15, or 25-80:1-57:1-30:1-30:1-40, preferably about 55:20:10:5:5:5. In yet another aspect, the atomic ratio of a Cu/Zn/Zr/Ba catalyst ranges from about 10-80:5-30:5-20:1-20:1-20, or 25-80:1-57:1-30:1-30:1-40, preferably about 55:10:15:10:10, about 60:15:10:10:5, and about 60:20:10:5:5. In still another aspect, the atomic ratio of a Zn/Zr/Ce/Rb ranges from about 10-80:5-30:5-20:1-20:1-20, or 25-80:1-57:1-30:1-30:1-40, preferably about 45:20:15:10:10. In some embodiments, the catalyst is Cu/Zn/Zr/Ce/Sr, preferably 45 at. % Cu/20 at. % Zn/15 at. % Zr/10 at. % Ce/10 at. % Sr.

[0050] Copper loading in the catalyst can be from 1 mole % to about 60 mole %, from about 20 mole % to about 60 mole %, and preferably from about 40 mole % to about 60 mole %. The metals used to prepare the catalyst of the present invention can be provided in various oxidation states such as metallic, oxide, hydrate, or salt forms typically depending on the propensity of each metals stability and/or physical/chemical properties. Preferably, the metals or metal oxides used in the preparation of the mixed metal oxide catalyst can be provided in stable oxidation states as complexes with monodentate, bidentate, tridentate, or tetradendate coordinating ligands. Non-limiting examples of ligands include such as for example iodide, bromide, sulfide, thiocyanate, chloride, nitrate, azide, fluoride, hydroxide, oxalate, water, isothiocyanate, acetonitrile, pyridine, ammonia, ethylenediamine, 2,2-bipyridine, 1,10-phenanthroline, nitrite, triphenylphosphine, cyanide, or carbon monoxide. In a preferred aspect, the mixed metal oxides used to prepare the catalysts of the current invention can be provided as nitrate, nitrate hydrates, nitrate trihydrates, and nitrate hexahydrates. By way of example, copper (II) nitrate trihydrate, zinc nitrate hexahydrate, zirconium (IV) oxynitrate hydrate, cerium (III) nitrate hexahydrate, yttrium (III) nitrate hexahydrate, lanthanum (III) nitrate hexahydrate, and barium nitrate can be used. Non-limiting examples of commercial sources of the above-mentioned metals and metal oxides, and metal complexes are Sigma Aldrich (U.S.A), Acros Organics (Thermo Fisher Scientific, U.S.A.), and Alfa Aesar (U.S.A.).

B. Methods of Making Mixed Metal Oxide Catalysts

[0051] The catalyst can be prepared by co-precipitation of metals, or salts thereof, from a solution containing oxalic acid followed by calcination of the precipitate. Co-precipitation is the simultaneous precipitation of one or more metal salts from a solution to form a mixed metal catalyst precursor. By way of example, a catalyst of the present invention can be prepared by gel oxalate co-precipitation. In a gel oxalate co-precipitation method, a solution of the desired metal salt or mixture of metal precursor material (e.g., metal nitrate salts of Cu, Zn, Zr, Ce, with Ba, La, Y, Sr, Tb, Rb, or any combination thereof) can be obtained by mixing the metal salt precursor material in the appropriate molar ratios together in a solvent (e.g., water or alcohol). A second mixture that includes oxalic acid dissolved in a solvent (e.g., methanol, ethanol, butanol, etc.) can be prepared. The two solutions can be added together slowly at room temperature (e.g., 20 C. to 35 C.) under agitation, preferably vigorous agitation. The contact the oxalic acid solution with the metal salt solution promotes precipitation of the catalyst precursor having (e.g., mixed metal oxalates). The formed precipitate can be collected by standard techniques, such as decanting, filtration, or centrifuging. In a preferred aspect, the precipitate can be centrifuged at a range from about 3000 rpm to about 7000 rpm, from about 4000 rpm to about 6000 rpm, and preferably about 5000 rpm for anywhere between 10 minutes and 30 minutes, preferably 15 minutes. The separated precipitate can be dried to remove water and/or solvent. By way of example, the precipitate can be dried overnight at temperature from about 100 C. to about 120 C., preferably 110 C. overnight to obtain a dried catalyst precursor. The catalyst precursor can be calcined (e.g., heated in the presence of an oxidant) to obtain the mixed metal oxide catalyst of the present invention. By way of example, the catalyst precursor can be heated for 2 to 6 hours at a temperature of 250 to 450 C. under a flow of air to obtain a mixed metal oxide catalyst. The mixed metal oxide catalyst can be reduced (e.g., subjected to a hydrogen flow for about 2 to 3 hours at a temperature of 180 C. to 350 C.).

[0052] In some aspects, the catalysts of the present invention are prepared under oxidative conditions (e.g., calcination) and the metals included in the heterogeneous catalyst are present in higher oxidation states, for example as oxides. Prior to being used as hydrogenation catalysts for the direct conversion of CO.sub.2 to methanol, the catalyst can be treated under reducing conditions to convert some or all of the metals to a lower, more active, oxidation state (e.g. a zero valence). In a preferred aspect, the prepared mixed metal oxide catalysts of the current invention are subjected to reducing conditions (e.g., a gaseous hydrogen stream) within the reactor or separately at a temperature ranging from about 220 C. to about 300 C., from about 250 C. to about 290 C. and preferably around 270 C. under 10 vol. % to 50 vol. % H.sub.2 in Ar, 20 vol. % to 40 vol. % H.sub.2 in Ar, and preferably 25 vol. % H.sub.2 in Ar for 1 h to 3 h, and preferably 2 h.

[0053] The catalysts of the present invention can be ground into a fine powder, micronized or nanonized to desired mesh particle size distributions, or pressed into pellets, crushed, and sieved to particle size ranges from about 100 m to about 600 m, from about 200 m to about 500 m, and preferably between 250 m and 425 m. Without wishing to be bound by theory, it is believed that the catalyst activity depends on the particle size of the metals in the mixed metal oxide catalyst, which depends mainly on electronic effects, as the electron density at the active sites (on the surface) can vary due to particle size. This effect can be closely related to particle shape and the number of low coordination sites (edges and corners) on the surface as well as the composition of the catalyst. The average CuO particle size can range from 10.5 to 11.4 nm. The mixed metal oxide catalyst can include copper in the Cu.sup.0 and Cu.sup.+1 oxidation states. The average Cu.sup.0 species particle size in the catalyst can range from 10.5 to 12.5 nm, and the average Cu.sup.+1 species particle size can range 8 to 10.5 nm.

[0054] In other instances, the catalysts of present invention can also be prepared by a solid transformation such as found in the preparation of epitaxial metals, unsupported bulk metals, amorphous alloys, or colloidal metals.

C. Hydrogen/Carbon Dioxide Stream

[0055] Carbon dioxide and hydrogen used in the present invention can be obtained from various sources. In one non-limiting instance, the carbon dioxide can be obtained from a waste or recycle gas stream (e.g., from a plant on the same site, like for example from ammonia synthesis) or after recovering the carbon dioxide from a gas stream. A benefit of recycling such carbon dioxide as a starting material in the process of the invention is that it can reduce the amount of carbon dioxide emitted to the atmosphere (e.g., from a chemical production site). The hydrogen may be from various sources, including streams coming from other chemical processes, like water splitting (e.g., photocatalysis, electrolysis, or the like), syngas production, ethane cracking, methanol synthesis, or conversion of methane to aromatics. Preferably, the hydrogen is obtained by water splitting. The H.sub.2/CO.sub.2 reactant gas stream ratio for the hydrogenation reaction can range from 1 to 5, or 1:1, 2:1, 3:1, 4:1, or 5:1, preferably 3:1 to 5:1 with the remainder of the reactant gas stream comprising another gas or gases provided the gas or gases are inert, such as argon (Ar) or nitrogen (N.sub.2), and do not negatively affect the reaction. All possible percentages of CO.sub.2+H.sub.2+inert gas are anticipated in the current embodiments as having the described H.sub.2/CO.sub.2 ratios herein. For example, in one instance the reactant stream includes 22 vol. % CO.sub.2, 67 vol. % H.sub.2, and 11 vol. % Ar. Preferably, the reactant mixture is highly pure and substantially devoid of water or steam. In some embodiments, the carbon dioxide can be dried prior to use (e.g., pass through a drying media) or contains a minimal amount of or no water.

D. Methanol Production System

[0056] Conditions sufficient for the hydrogenation of CO.sub.2 to methanol include temperature, time, space velocity, and pressure. The temperature range for the hydrogenation reaction can range from about 200 C. to 300 C., from about 210 C. to 280 C., preferably from about 220 C. to about 260 C. and all ranges there between including 221 C., 222 C., 223 C., 224 C., 225 C., 226 C., 227 C., 228 C., 229 C., 230 C., 231 C., 232 C., 233 C., 234 C., 235 C., 236 C., 237 C., 238 C., 239 C., 240 C., 241 C., 242 C., 243 C., 244 C., 245 C., 246 C., 247 C., 248 C., 249 C., 250 C., 251 C., 252 C., 253 C., 254 C., 255 C., 256 C., 257 C., 258 C., and 259 C. The gas hourly space velocity (GHSV) for the hydrogenation reaction can range from about 2,500 h.sup.1 to about 20,000 h.sup.1, from about 3,500 h.sup.1 to about 10,000 h.sup.1, and preferably from about 4,000 h.sup.1 to about 6,000 h.sup.1. The average pressure for the hydrogenation reaction can range from about 1 bar to about 100 bar (0.1 MPa to 10 MPa), from about 0.2 MPa to about 6 MPa, preferably about 3 MPa to about 5 MPa and all pressures there between including 3.1 MPa, 3.2 MPa, 3.3 MPa, 3.4 MPa, 3.5 MPa, 3.6 MPa, 3.7 MPa, 3.8 MPa, 3.9 MPa, 4.0 MPa, 4.1 MPa, 4.2 MPa, 4.3 MPa, 4.4 MPa, 4.5 MPa, 4.6 MPa, 4.7 MPa, 4.8 MPa, and 4.9 MPa, or more. The upper limit on pressure can be determined by the reactor used. The conditions for the hydrogenation of CO.sub.2 to methanol can be varied based on the type of the reactor.

[0057] In another aspect, the reaction can be carried out over the catalyst of the current invention having the particular methanol selectivity and conversion for prolonged periods of time without changing or re-supplying new catalyst or preforming catalyst regeneration. This can be due to the stability or slower deactivation of the catalysts of the present invention. In one aspect, the reaction can be performed where the one pass methanol selectivity is at least 10 to 100%, or at least 25%, at least 15 to 22%, or more. In some instances, the methanol selectivity can be 18 to 21% after 100 hours to 800 hours on the stream. In another aspect, the one pass CO.sub.2 conversion is at least 5% or more, or at least 5% to 99%, 10% to 80%, or 20% to 60%. In some embodiments, the CO.sub.2 conversion is at least 5% to 60% after 100 hours to 800 hours on the stream. The catalysts of the present invention can remain 90 to 99% active, preferably 94 to 98% active, after 350 hours or more of time on the stream. The method can further include collecting or storing the produced methanol along with using the produced methanol as a feed source, solvent or a commercial product. Prior to use, the catalyst can be subjected to reducing conditions to convert the copper oxide (Cu.sup.+2) to Cu.sup.+1 and Cu.sup.0 species. A non-limiting example of reducing conditions includes flowing a gaseous stream that includes hydrogen gas (e.g., a H.sub.2 and Argon gas stream) at a temperature of 250 to 280 C. for a period of time (e.g., 1, 2, or 3 hours).

[0058] FIG. 1 depicts a system 10 that can be used to convert carbon dioxide (CO.sub.2) and hydrogen (H.sub.2) to methanol using the mixed metal oxide catalysts of the present invention. The system 10 can include an H.sub.2/CO.sub.2 source 12, a reactor 14, and a collection device 16. The H.sub.2/CO.sub.2 source 12 can be configured to be in fluid communication with the reactor 14 via an inlet 18 on the reactor. As explained above, the CO.sub.2/H.sub.2 feed source 12 can be configured such that it regulates the amount of reactant feed entering the reactor 14. As shown, the CO.sub.2/H.sub.2 feed source 12 is one unit feeding into one inlet 18, however, it should be understood that the number of inlets and/or separate feed sources can be adjusted to reactor sizes and/or configurations. The reactor 14 can include a reaction zone 20 having the mixed metal oxide catalyst 22 of the present invention. The reactor can include various automated and/or manual controllers, valves, heat exchangers, gauges, etc. necessary for the operation of the reactor. The reactor can be have the necessary insulation and/or heat exchangers to heat or cool the reactor as necessary. The amounts of the CO.sub.2/H.sub.2 feed and the mixed metal oxide catalyst 22 used can be modified as desired to achieve a given amount of product produced by the system 10. Non-limiting examples of continuous flow reactors that can be used include fixed-bed reactors, fluidized reactors, bubbling bed reactors, slurry reactors, rotating kiln reactors, moving bed reactors or any combinations thereof when two or more reactors are used. In preferred aspects, reactor 14 is a continuous flow fixed-bed reactor. The reactor 14 can include an outlet 24 configured to be in fluid communication with the reaction zone and configured to remove a first product stream comprising methanol from the reaction zone 20. Reaction zone 20 can further include the reactant feed and the first product stream. The products produced can include methanol, carbon monoxide, and water. In some aspects, the catalyst can be included in the product stream. The collection device 16 can be in fluid communication with the reactor 14 via the outlet 24. Both the inlet 18 and the outlet 24 can be opened and closed as desired. The collection device 16 can be configured to store, further process, or transfer desired reaction products (e.g., methanol) for other uses. In a non-limiting example, collection device can be a separation unit or a series of separation units that are capable of separating the liquid components from the gaseous components from the product stream. By way of example, the methanol and water can be condensed from the gas stream. Any unreacted H.sub.2/CO.sub.2 can be recycled and included in the H.sub.2/CO.sub.2 feed to further maximize the overall conversion of H.sub.2/CO.sub.2 to methanol, increases the efficiency and commercial value of the H.sub.2/CO.sub.2 to methanol conversion process of the present invention. The water can be removed from the methanol using known drying/separation methods for the removal of water from methanol. The resulting methanol can be sold, stored or used in other processing units as a feed source. Still further, the system 10 can also include a heating/cooling source 26. The heating/cooling source 26 can be configured to heat or cool the reaction zone 20 to a temperature sufficient (e.g., 220 to 260 C.) to convert the H.sub.2/CO.sub.2 in the H.sub.2/CO.sub.2 feed to methanol. Non-limiting examples of a heating/cooling source 20 can be a temperature controlled furnace or an external, electrical heating block, heating coils, or a heat exchanger.

EXAMPLES

[0059] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters, which can be changed or modified to yield essentially the same results.

Catalyst Preparation

Example 1

Synthesis of Cu/Zn/Zr/Ce/Y

[0060] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and yttrium of 55:10:15:10:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.27 g of copper (II) nitrate trihydrate, 1.36 g of zinc nitrate hexahydrate and 1.14 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 1.29 g of yttrium (III) nitrate hexahydrate) and (ii) oxalic acid (6.12 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 2

Synthesis of Cu/Zn/Zr/Ce/Y

[0061] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and yttrium of 60:20:10:5:5 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.84 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 0.76 g of zirconium (IV) oxynitrate hydrate, 0.46 g of cerium (III) nitrate hexahydrate and 0.65 g of yttrium (III) nitrate hexahydrate) and (ii) oxalic acid (6.55 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention. The catalyst particle size was calculated from XRD results by Scherrer formula and was found to be 11.4 nm for Cu.sup.2+, 10.5 nm for Cu.sup.+, and 10.5 nm Cu.sup.0. FIG. 2 is XRD patterns for fresh (top pattern) and used (bottom pattern) for Example 2 catalyst. Lines 200 show peaks specific to metallic copper.

Example 3

Synthesis of Cu/Zn/Zr/Ce/Y

[0062] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and yttrium of 60:15:10:5:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.84 g of copper (II) nitrate trihydrate, 2.05 g of zinc nitrate hexahydrate and 0.76 g of zirconium (IV) oxynitrate hydrate, 0.46 g of cerium (III) nitrate hexahydrate and 1.29 g of yttrium (III) nitrate hexahydrate) and (ii) oxalic acid (6.42 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 4

Synthesis of Cu/Zn/Zr/Ce/Y

[0063] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and yttrium of 60:15:10:10:5 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.84 g of copper (II) nitrate trihydrate, 2.05 g of zinc nitrate hexahydrate and 0.76 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.65 g of yttrium (III) nitrate hexahydrate) and (ii) oxalic acid (6.36 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 5

Synthesis of Cu/Zn/Zr/Ce/Y

[0064] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and yttrium of 65:20:5:5:5 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (7.41 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 0.38 g of zirconium (IV) oxynitrate hydrate, 0.46 g of cerium (III) nitrate hexahydrate and 0.65 g of yttrium (III) nitrate hexahydrate) and (ii) oxalic acid (6.66 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 6

Synthesis of Cu/Zn/Zr/Ce/La

[0065] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and lanthanum of 45:20:15:10:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (5.13 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 1.14 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.70 g of lanthanum (III) nitrate hexahydrate) and (ii) oxalic acid (5.91 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 7

Synthesis of Cu/Zn/Zr/Ce/La

[0066] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and lanthanum of 60:10:10:10:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.84 g of copper (II) nitrate trihydrate, 1.36 g of zinc nitrate hexahydrate and 0.76 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.70 g of lanthanum (III) nitrate hexahydrate) and (ii) oxalic acid (6.04 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 8

Synthesis of Cu/Zn/Zr/Ce/La

[0067] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and lanthanum of 65:20:5:5:5 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (7.41 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 0.38 g of zirconium (IV) oxynitrate hydrate, 0.46 g of cerium (III) nitrate hexahydrate and 0.35 g of lanthanum (III) nitrate hexahydrate) and (ii) oxalic acid (6.56 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention. The catalyst particle size was calculated from XRD results by Scherrer formula and was found to be 12.5 nm for Cu.sup.2+, 8 nm for Cu.sup.+, and 10.5 nm for Cu.sup.0. FIG. 3 shows XRD patterns for fresh (top pattern) and used (bottom pattern) Example 3 catalyst. Lines 300 show peaks specific to reduced copper.

Example 9

Synthesis of Cu/Zn/Zr/Ce/Y/La

[0068] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium, yttrium and lanthanum of 55:20:10:5:5:5 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.27 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 0.76 g of zirconium (IV) oxynitrate hydrate, 0.46 g of cerium (III) nitrate hexahydrate, 0.65 g of yttrium (III) nitrate hexahydrate and 0.35 g of lanthanum (III) nitrate hexahydrate) and (ii) oxalic acid (6.31 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 10

Synthesis of Cu/Zn/Zr/Ce/Ba

[0069] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and barium of 55:10:15:10:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.27 g of copper (II) nitrate trihydrate, 1.36 g of zinc nitrate hexahydrate and 1.14 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.57 g of barium nitrate) and (ii) oxalic acid (5.88 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention. FIG. 4 is an XRD pattern of the catalyst.

Example 11

Synthesis of Cu/Zn/Zr/Ce/Ba

[0070] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and barium of 60:15:10:10:5 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.84 g of copper (II) nitrate trihydrate, 2.05 g of zinc nitrate hexahydrate and 0.76 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.29 g of barium nitrate) and (ii) oxalic acid (6.24 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 12

Synthesis of Cu/Zn/Zr/Ce/Ba

[0071] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and barium of 60:20:10:5:5 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (6.84 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 0.76 g of zirconium (IV) oxynitrate hydrate, 0.46 g of cerium (III) nitrate hexahydrate and 0.29 g of barium nitrate) and (ii) oxalic acid (6.43 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention. FIG. 5 shows an XRD pattern of the Cu/Zn/Zr/Ce/Ba catalyst.

Example 13

Synthesis of Cu/Zn/Zr/Ce/Rb

[0072] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and rubidium of 45:20:15:10:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (5.13 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 1.14 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.52 g of rubidium nitrate) and (ii) oxalic acid (6.20 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 14

Synthesis of Cu/Zn/Zr/Ce/Tb

[0073] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and terbium of 45:20:15:10:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (5.13 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 1.14 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.86 g of terbium nitrate hexahydrate) and (ii) oxalic acid (5.96 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Example 15

Synthesis of Cu/Zn/Zr/Ce/Sr

[0074] The catalyst with an atomic ratio of copper, zinc, zirconium, cerium and terbium of 45:20:15:10:10 were prepared by gel oxalate co-precipitation using 20% excess of oxalic acid. Two separate solutions were prepared (i) a mixture of nitrates (5.13 g of copper (II) nitrate trihydrate, 2.73 g of zinc nitrate hexahydrate and 1.14 g of zirconium (IV) oxynitrate hydrate, 0.93 g of cerium (III) nitrate hexahydrate and 0.72 g of strontium nitrate) and (ii) oxalic acid (5.91 g) dissolved in ethanol. The two solutions were mixed slowly at room temperature under vigorous stirring. The formed precipitate was separated by centrifuge with 5000 rpm for 15 minutes, and then dried at 110 C. overnight to form the catalyst precursor. The catalyst precursor was calcined at 350 C. for 4 h to obtain the mixed metal catalyst of the present invention.

Catalyst Testing

General Procedure

[0075] Catalyst testing was performed in a high throughput reactor system provided by HTE Company, Germany. The reactors are fixed bed type reactor with 0.5 cm inner diameter and 60 cm in length. Gas flow rates were regulated using Brooks SLA5800 mass flow controllers. Reactor pressure was maintained by restricted capillary before and after the reactor. The reactor temperature was maintained by an external, electrical heating block. The effluent of the reactors is connected to Agilent gas chromatography (GC) 7867 A for online gas analysis. Catalysts were pressed into pellets then crushed and sieved between 250-425 m. A 0.25 ml of catalyst sieved fraction was placed on top of inert material inside the reactor. Prior to the reaction test, the catalyst in oxidized state was reduced at 270 C. under 25 vol. % H.sub.2 in Ar for 2 h. A mixture of 22 vol. % CO.sub.2+67 vol. % H.sub.2+11 vol. % Ar with gas hourly space velocity (GHSV)=2500, 5000, or 10000 h.sup.1 was introduced into the reactor at 30 and 40 bar and different reaction temperature (e.g., 220, 230, and 240 C.). Argon was used as an internal standard for GC analysis. CO.sub.2 conversion as well as methanol selectivity and yield were calculated as follows:

[00001]$X_{\mathrm{CO}.Math..Math.2}=\frac{\left[\mathrm{CO}\right]+\left[{\mathrm{CH}}_4\right]+2\left[C_2.Math.H_6\right]+\left[{\mathrm{CH}}_3.Math.\mathrm{OH}\right]}{{\left[{\mathrm{CO}}_2\right]}_{.Math.i.Math..Math.n}}$$S_{\mathrm{CH}.Math..Math.3.Math..Math.\mathrm{OH}}=\frac{\left[{\mathrm{CH}}_3.Math.\mathrm{OH}\right]}{\left[\mathrm{CO}\right]+\left[{\mathrm{CH}}_4\right]+2\left[C_2.Math.H_6\right]+\left[{\mathrm{CH}}_3.Math.\mathrm{OH}\right]}$$Y_{\mathrm{CH}.Math..Math.3.Math..Math.\mathrm{OH}}=X_{\mathrm{CO}.Math..Math.2}{S}_{\mathrm{CH}.Math..Math.3.Math..Math.\mathrm{OH}}$

[0076] All catalysts that were tested in this invention showed high catalytic activity and stability. The commercial catalyst showed about 6% reduction in its activity over 350 h while the best performance catalyst of this invention showed only about 2.5% reduction in its activity over same period of time. The commercial catalyst was obtained from Sd-Chemie (Germany) and had the following composition: 60 wt % CuO/30 wt % ZnO/7.5 wt % Al.sub.2O.sub.3.

Example 16

Cu/Zn/Zr/Ce/Y Testing

[0077] Cu/Zn/Zr/Ce/Y catalysts of the present invention at various atomic ratios (Examples 1-5) were tested under the conditions described in the general procedure. FIG. 6 shows the activity, i.e., methanol yield versus time on stream (TOS), of the catalysts of Examples 1-5 at different temperatures and GHSVs. Circle line monikers is the Example 1 catalyst data, square line monikers is the Example 2 catalyst data, diamond line monikers is the Example 4 catalyst data, triangle line monikers is the Example 3 catalyst data, and side triangle line monikers is Example 5 catalyst data. Table 1 lists the data for FIG. 6. FIG. 7 shows the specific activity of the catalyst prepared in Example 2 (60% Cu/20% Zn/10% Zr/5% Ce/5% Y by weight) at different gas hourly space velocities. Upside down triangle line monikers are data at a GSHV of 2500 1/h, circle line monikers are data at a GSHV of 5000 1/h, and square line monikers are data at a GSHV of 10,000 1/h. The highest methanol yield with this catalyst was shown to be 21% at H.sub.2/CO.sub.2 of 3:1, temperature of 240 C., pressure of 40 bar, and gas hourly space velocity of 5000 h.sup.1.

TABLE-US-00001 TABLE 1 Catalyst Methanol Yield (%) Reaction Conditions: T = 240 C., P = 40 bar GHSV = 5000 h.sup.1 (atomic %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Y 10.6 60%Cu/20%Zn/10%Zr/5%Ce/5%Y 11.8 60%Cu/15%Zn/10%Zr/10%Ce/5%Y 10.3 60%Cu/15%Zn/10%Zr/5%Ce/10%Y 10.3 65%Cu/20%Zn/5%Zr/5%Ce/5%Y 10.9 Reaction Conditions: T = 240 C., P = 40 bar GHSV = 2500 h.sup.1 (mole %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Y 10.7 60%Cu/20%Zn/10%Zr/5%Ce/5%Y 11.9 60%Cu/15%Zn/10%Zr/10%Ce/5%Y 10.5 60%Cu/15%Zn/10%Zr/5%Ce/10%Y 10.4 65%Cu/20%Zn/5%Zr/5%Ce/5%Y 11.3 Reaction Conditions: T = 220 C., P = 40 bar GHSV = 2500 h.sup.1 (atomic %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Y 11.4 60%Cu/20%Zn/10%Zr/5%Ce/5%Y 12.8 60%Cu/15%Zn/10%Zr/10%Ce/5%Y 10.4 60%Cu/15%Zn/10%Zr/5%Ce/10%Y 9.9 65%Cu/20%Zn/5%Zr/5%Ce/5%Y 11.5 Reaction Conditions: T = 220 C., P = 40 bar GHSV = 5000 h.sup.1 (atomic %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Y 10 60%Cu/20%Zn/10%Zr/5%Ce/5%Y 10.8 60%Cu/15%Zn/10%Zr/10%Ce/5%Y 8.8 60%Cu/15%Zn/10%Zr/5%Ce/10%Y 8.3 65%Cu/20%Zn/5%Zr/5%Ce/5%Y 9.9

Example 17

Cu/Zn/Zr/Ce/La Testing

[0078] Cu/Zn/Zr/Ce/La catalysts of the present invention at various atomic (molar) loadings (Examples 6-9) were tested using the conditions described in the general procedure. FIG. 8 shows the activity, i.e., methanol yield versus time on stream (TOS), of the catalysts of Examples 6-8 at different temperatures and GHSVs. Circle line monikers is Example 6 catalyst data, square line monikers is Example 7 catalyst data, diamond line monikers is Example 8 catalyst data. Table 2 lists the data for FIG. 8. FIG. 9 shows the specific activity of the Example 8 catalyst (65 at. % Cu/20 at. % Zn/5 at. % Zr/5 at. % Ce/5 at. % La) at different temperatures and GHSVs. Inverted triangle line monikers is data at GHSV of 2500 1/h, circle line monikers is data at a GSHV of 5000 1/h, and square line monikers is data at a GSHV of 10,000 1/h. The highest methanol yield with this catalyst was shown to be 18% at H.sub.2/CO.sub.2 of 3:1, temperature of 240 C., pressure of 40 bar, and gas hourly space velocity of 5000 1/h.

TABLE-US-00002 TABLE 2 Catalyst Methanol Yield (%) Reaction Conditions: T = 240 C., P = 40 bar GHSV = 5000 h.sup.1 (atomic %) 45%Cu/20%Zn/15%Zr/10%Ce/10%La 10.4 60%Cu/10%Zn/10%Zr/10%Ce/10%La 10.8 65%Cu/20%Zn/5%Zr/5%Ce/5%La 11 Reaction Conditions: T = 240 C., P = 40 bar GHSV = 2500 h.sup.1 (atomic %) 45%Cu/20%Zn/15%Zr/10%Ce/10%La 10.7 60%Cu/10%Zn/10%Zr/10%Ce/10%La 11.2 65%Cu/20%Zn/5%Zr/5%Ce/5%La 11.1 Reaction Conditions: T = 220 C., P = 40 bar GHSV = 2500 h.sup.1 (atomic %) 45%Cu/20%Zn/15%Zr/10%Ce/10%La 9.6 60%Cu/10%Zn/10%Zr/10%Ce/10%La 10.5 65%Cu/20%Zn/5%Zr/5%Ce/5%La 10.7 Reaction Conditions: T = 220 C., P = 40 bar GHSV = 5000 h.sup.1 (atomic %) 45%Cu/20%Zn/15%Zr/10%Ce/10%La 8.2 60%Cu/10%Zn/10%Zr/10%Ce/10%La 9 65%Cu/20%Zn/5%Zr/5%Ce/5%La 9.3

Example 18

Cu/Zn/Zr/Ce/Ba Testing

[0079] Cu/Zn/Zr/Ce/Ba catalysts of the present invention (Example 12) were tested as described in the general procedure. FIG. 10 shows the activity, i.e., methanol yield versus time on stream (TOS), of the catalysts of Examples 10-12 at different temperatures and gas hourly space velocities. Circle line monikers are Example 10 catalyst data, square line monikers is Example 11 catalyst data, and diamond line monikers is Example 12 catalyst data. Table 3 lists the data for FIG. 10. FIG. 11 shows the specific activity of the Example 12 catalyst (60% Cu/20% Zn/10% Zr/5% Ce/5% Ba) at different temperatures and gas hourly space velocities. Inverted triangle line monikers is data at a GHSV or 2500 1/h, circle line monikers is data at a GHSV of 5000 1/h, and square line monikers is data at a GHSV of 10000 1/h. It was determined that the highest methanol yield with this catalyst was shown to be 20% at H.sub.2/CO.sub.2 of 3, temperature of 240 C., pressure of 40 bar (4.0 MPa), and gas hourly space velocity of 5000 h.sup.1.

TABLE-US-00003 TABLE 3 Catalyst Methanol Yield (%) Reaction Conditions: T = 240 C., P = 40 bar GHSV = 5000 h.sup.1 (atomic %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Ba 10.6 60%Cu/15%Zn/10%Zr/10%Ce/5%Ba 10.5 60%Cu/20%Zn/10%Zr/5%Ce/5%Ba 11 Reaction Conditions: T = 240 C., P = 40 bar GHSV = 2500 h.sup.1 (atomic %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Ba 11 60%Cu/15%Zn/10%Zr/10%Ce/5%Ba 10.9 60%Cu/20%Zn/10%Zr/5%Ce/5%Ba 11.6 Reaction Conditions: T = 220 C., P = 40 bar GHSV = 2500 h.sup.1 (atomic %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Ba 10 60%Cu/15%Zn/10%Zr/10%Ce/5%Ba 10.5 60%Cu/20%Zn/10%Zr/5%Ce/5%Ba 10.9 Reaction Conditions: T = 220 C., P = 40 bar GHSV = 5000 h.sup.1 (atomic %) 55%Cu/10%Zn/15%Zr/10%Ce/10%Ba 8.5 60%Cu/15%Zn/10%Zr/10%Ce/5%Ba 8.9 60%Cu/20%Zn/10%Zr/5%Ce/5%Ba 9

Example 19

Cu/Zn/Zr/Ce/Rb Testing

[0080] Cu/Zn/Zr/Ce/Rb catalysts of the present invention (Example 14) were tested as described in the general procedure. FIG. 12 shows the activity, i.e., methanol yield versus time on stream (TOS), carbon dioxide conversion and methanol yield for the Example 13 catalyst at different temperatures and gas hourly space velocities. Circle line monikers represent data for carbon dioxide conversion, square line monikers represent data for methanol selectivity, and diamond line monikers represent data for methanol yield. Table 4 lists the data for FIG. 12.

TABLE-US-00004 TABLE 4 Methanol Catalyst (atomic %) Reaction conditions Yield (%) 45%Cu/20%Zn/15% T = 240 C., P = 30 bar 10.1 Zr/10%Ce/10%Rb GHSV = 5000 h.sup.1 45%Cu/20%Zn/15% T = 220 C., P = 30 bar 10 Zr/10%Ce/10%Rb GHSV = 2500 h.sup.1 45%Cu/20%Zn/15% T = 220 C., P = 30 bar 9.8 Zr/10%Ce/10%Rb GHSV = 5000 h.sup.1

Example 20

Cu/Zn/Zr/Ce/Tb Testing

[0081] Cu/Zn/Zr/Ce/Tb catalysts of the present invention were tested as described in the general procedure. FIG. 13 shows the activity, i.e., methanol yield versus time on stream (TOS), carbon dioxide conversion and methanol yield for the Example 14 catalyst at different temperatures and gas hourly space velocities. Circle line monikers represent data for carbon dioxide conversion, square line monikers represent data for methanol selectivity, and diamond line monikers represent data for yield. Table 5 lists the data for FIG. 13.

TABLE-US-00005 TABLE 5 Meth- CO.sub.2 anol Conver- Selec- Catalyst (atomic %) Reaction conditions Yield sion tivity 45%Cu/20%Zn/15% T = 240 C., P = 40 11 15.5 29 Zr/10%Ce/10%Tb bar GHSV = 10000 h.sup.1 45%Cu/20%Zn/15% T = 260 C., P = 40 12.8 21.7 58.7 Zr/10%Ce/10%Tb bar GHSV = 10000 h.sup.1 45%Cu/20%Zn/15% T = 240 C., P = 40 11 21 55 Zr/10%Ce/10%Tb bar GHSV = 5000 h.sup.1

Example 21

Cu/Zn/Zr/Ce/Sr Testing

[0082] Cu/Zn/Zr/Ce/Sr catalysts of the present invention (Example 15) were tested as described in the general procedure. FIG. 14 shows the activity, i.e., methanol yield versus time on stream (TOS), carbon dioxide conversion and methanol yield for the Example 15 catalyst at different temperatures and gas hourly space velocities. Circle line monikers represent data for carbon dioxide conversion, square line monikers represent data for methanol selectivity, and diamond line monikers represent data for yield.

[0083] From the testing of the catalysts, all catalysts of the present invention were able to produce methanol from carbon dioxide at low temperatures and pressures. It was surprisingly found that the catalysts of the present invention that contained yttrium showed higher methanol yield as compare to other catalysts of the present invention. The methanol yield increased from about 13% at 30 bar (3.0 MPa) to about 21% at 40 bar (4.0 MPa). Table 6 lists the data for FIG. 14.

TABLE-US-00006 TABLE 6 Meth- CO.sub.2 anol Conver- Selec- Catalyst (atomic %) Reaction conditions Yield sion tivity 45%Cu/20%Zn/15% T = 260 C., P = 40 16.8 30 56 Zr/10%Ce/10%Sr bar GHSV = 5000 h.sup.1 45%Cu/20%Zn/15% T = 260 C., P = 40 17.7 32 55 Zr/10%Ce/10%Sr bar GHSV = 10000 h.sup.1

Example 22

Cu/Zn/Zr/Ce/Y/La Testing

[0084] The Cu/Zn/Zr/Y/La catalysts of Example 9 were tested as described in the general procedure at 240 C. and 260 C. FIG. 15 shows the activity, i.e., methanol yield versus time on stream (TOS), methanol yield for the Example 9 catalyst at different temperatures and constant pressure and gas hourly space velocity. Circle line monikers represent data for methanol yield at 240 C., and square line monikers represent data for methanol yield at 260 C. Table 7 lists the methanol selectivity and the carbon dioxide conversion data for the Example 9 catalyst at a pressure of 40 bar (4.0 MPa), GHSV of 5000 h.sup.1 and different temperatures.

TABLE-US-00007 TABLE 7 Meth- CO.sub.2 anol Conver- Selec- Catalyst (atomic %) Reaction conditions Yield sion tivity 55%Cu/20%Zn/10% T = 240 C., P = 40 17.9 20 85 Zr/5%Ce/5%Y/5%La bar GHSV = 5000 h.sup.1 55%Cu/20%Zn/10% T = 260 C., P = 40 14.8 18.8 79 Zr/5%Ce/5%Y/5%La bar GHSV = 5000 h.sup.1