WO2017085593A2

WO2017085593A2 - High temperature methods for hydrogenation of co2 to syngas for production of olefins

Info

Publication number: WO2017085593A2
Application number: PCT/IB2016/056747
Authority: WO
Inventors: Shahid Shaikh; Clark Rea; Aghaddin Mamedov
Original assignee: Sabic Global Technologies B.V.
Priority date: 2015-11-16
Filing date: 2016-11-09
Publication date: 2017-05-26
Also published as: WO2017085593A3

Abstract

Methods of preparing syngas are provided. An exemplary method can include hydrogenation of carbon dioxide (CO₂) via a reverse water gas shift (RWGS) reaction. Catalysts that include Cr can be used, and the RWGS reaction can be conducted at a temperature of 800 °C or greater.

Description

HIGH TEMPERATURE METHODS FOR HYDROGENATION OF C0₂ TO

SYNGAS FOR PRODUCTION OF OLEFINS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 62/255,937, filed November 16, 2015. The contents of the referenced application are incorporated into the present application by reference.

FIELD

[0002] The presently disclosed subject matter relates to methods for high temperature conversion of carbon dioxide (C0₂) into synthesis gas (syngas) via hydrogenation of C0₂.

BACKGROUND

[0003] Synthesis gas (also known as syngas) is a mixture of carbon monoxide (CO) and hydrogen (H₂). Syngas can be prepared by reacting C0₂ with H₂. This process can be described as a hydrogenation of C0₂. C0₂ and H₂ can react to form carbon monoxide (CO) and water (H₂0) through a reverse water gas shift (RWGS) reaction. The RWGS reaction is endothermic and can be described by the following equation:

(1) C0₂ + H₂→ CO + H₂0 A_RH°3oo_°c = 38 kJ/mol

The RWGS reaction is reversible; the reverse reaction (from CO and H₂0 to C0₂ and H₂) is known as the water gas shift reaction. The RWGS reaction can be conducted under conditions that provide partial conversion of C0₂ and H₂, thereby creating an overall product mixture that includes C0₂, H₂, CO, and H₂0. C0₂ and H₂0 can optionally be removed from such a product mixture, thereby providing a purified syngas mixture containing primarily CO and H₂.

[0004] Syngas is a versatile mixture that can be used to prepare light olefins, methanol, acetic acid, aldehydes, and many other important industrial chemicals. However, the efficiency of the preparation of different chemicals, for example, methanol versus light olefins, from syngas can depend on the composition of the syngas. Syngas containing H₂ and CO in a molar ratio (H₂:CO) of about 2: 1 can be useful for olefin synthesis.

[0005] A disadvantage of many existing methods of preparing syngas is that they tend to produce syngas having a high H₂:CO molar ratio which is not suitable for olefin synthesis. Additionally, reactions at high temperatures can lead to fusing of the active sites of mixed oxide catalysts to non-oxide catalysts, limiting the reaction.

[0006] Thus, there remains a need in the art for new methods for conversion of C0₂ into syngas with H₂:CO ratios compatible with olefin synthesis, improved catalyst stability, improved yield, and improved overall economy. SUMMARY OF THE DISCLOSED SUBJECT MATTER

[0007] The presently disclosed subject matter provides a method of preparing syngas, which can include providing a reaction chamber that comprises a catalyst comprising Cu and Mn. The method can further include feeding a reaction mixture comprising H₂ and C0₂ to the reaction chamber and contacting H₂ and C0₂ with the catalyst at a reaction temperature greater than 800 °C to provide a product mixture that comprises H₂ and CO.

[0008] In certain embodiments, the catalyst can include Cu and Mn in a molar ratio of about 4: 1 to about 1 :4, or a molar ratio of about 1 : 1.

[0009] In certain embodiments, the catalyst can further include one or more solid supports selected from the group consisting of A1₂0₃, MgO, Si0₂, Ti0₂, and Zr0₂.

[0010] In certain embodiments, the catalyst can include one or more additional metals selected from the group consisting of La, Ca, K, W, and Al. In certain embodiments, the catalyst includes Al.

[0011] In certain embodiments, the catalyst can include about 10% Cu and about 10% Mn, by weight.

[0012] In certain embodiments, the reaction mixture can include H₂ and C0₂ in a molar ratio (H₂ : C0₂) of about 1.5 : 1.

[0013] In certain embodiments, the reaction temperature is greater than about 800 °C, greater than about 825 °C, or is about 850 °C.

[0014] In certain embodiments, the product mixture can include H₂ and CO in a molar ratio (H₂:CO) of about 1 : 1 to about 3 : 1, about 1.5: 1 to about 3 : 1, about 2: 1 to about 3 : 1, about 2.36: 1 or about 2.26: 1.

[0015] In certain embodiments, the product mixture further includes C0₂ and H₂0. In certain embodiments, the product mixture can include less than about 25% C0₂, by mole or less than about 15% C0₂, by mole.

[0016] In certain embodiments, the method can include separating at least a portion of C0₂ and H₂0 from the product mixture to provide purified syngas.

[0017] The presently disclosed subject matter provides a method of preparing light olefins, which can include providing a reaction chamber that can include a catalyst comprising Cu and Mn. In certain embodiments, the method further includes feeding a reaction mixture comprising H₂ and C0₂ to the reaction chamber and contacting H₂ and C0₂ with the catalyst at a reaction temperature greater than or equal to about 800 °C to provide a product mixture that comprises H₂, CO, C0₂, and H₂0. In certain embodiments, the method further includes separating at least a portion H₂0 from the product mixture. In certain embodiments, the method also includes subjecting the product mixture to a Fischer-Tropsch synthesis (FT) reaction to provide light olefins.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a schematic diagram presenting an exemplary process for integration of C0₂ to the syngas process for producing olefins. [0019] FIG. 2 is a schematic diagram presenting an exemplary process for integration of C0₂ to the syngas process for producing olefins.

[0020] FIG. 3 is a schematic diagram presenting an exemplary process for integration of CO₂ to the syngas process for producing olefins.

DETAILED DESCRIPTION

[0021] There remains a need in the art for new methods of preparing syngas from CO₂. The presently disclosed subject matter provides novel methods of converting CO₂ and H₂ into syngas at high temperatures with H₂:CO ratios compatible with olefin synthesis and improved catalyst stability. The presently disclosed subject matter also provides improved methods of preparing light olefins. The presently disclosed subject matter includes the surprising discovery that Copper-Manganese-Aluminum (Cu-Mn-Al) catalysts can be used to promote hydrogenation of CO₂ at temperatures including and above about 800 °C. Such catalysts can be stable at these high temperatures and the use of reaction temperatures including and greater than 800 °C can provide improved conversion of C0₂, improved ratios of H₂:CO, and improved yield.

[0022] As used herein, the term "about" or "approximately" means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, "about" can mean a range of up to 20%, up to 10%, up to 5%), and or up to 1% of a given value.

Reactors and Reaction Chambers

[0023] The methods of the present disclosure can involve fixed bed isothermal or adiabatic reactors suitable for reactions of gaseous reactants and reagents catalyzed by solid catalysts. The reactor can be constructed of any suitable materials capable of holding high temperatures, for example from about 800°C to about 850°C. Non-limiting examples of such materials can include metals, alloys (including steel), glasses, ceramics or glass lined metals, and coated metals. The reactor can also include a reaction vessel enclosing a reaction chamber.

[0024] The dimensions of the reaction vessel and reaction chamber are variable and can depend on the production capacity, feed volume, and catalyst. The geometries of the reactor can be adjustable in various ways known to one of ordinary skill in the art.

[0025] In certain embodiments, reaction conditions within the reaction chamber can be isothermal. That is, hydrogenation of C0₂ can be conducted under isothermal conditions. In certain alternative embodiments, a temperature gradient can be established within the reaction chamber. For example, hydrogenation of C0₂ can be conducted across a temperature gradient using an adiabatic reactor.

[0026] The pressure within the reaction chamber can be varied, as is known in the art. In certain embodiments, the pressure within the reaction chamber can be atmospheric pressure, i.e., about 1 bar.

Catalysts

[0027] Catalysts suitable for use in conjunction with the presently disclosed matter can be catalysts capable of catalyzing RWGS reactions, i.e., hydrogenation of C0₂. In certain embodiments, the catalyst can be a solid catalyst, e.g., a solid-supported catalyst. The catalyst can be a metal oxide or mixed metal oxide. In certain embodiments, the catalyst can be located in a fixed packed bed, i.e., a catalyst fixed bed. In certain embodiments, the catalyst can include solid pellets, granules, plates, tablets, or rings.

[0028] In certain embodiments, the catalyst can include one or more transition metals. The catalyst can include copper (Cu) or manganese (Mn). In certain embodiments, the catalyst can include both Cu and Mn. In certain embodiments, the catalyst can include Cu and Mn in a molar ratio of about 10: 1 to about 1 : 10, about 4: 1 to about 1 :4, or about 1 : 1 (Cu:Mn). By way of non-limiting example, the molar ratio of Cu:Mn in the catalyst can be about 10: 1, 9: 1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2.5:1, 2:1, 1.8:1, 1.6:1, 1.5:1, 1.4:1, 1.3:1, 1.2:1, 1.1:1, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.8, 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10.

[0029] In certain embodiments, the catalyst can include a solid support. That is, the catalyst can be solid-supported. In certain embodiments, the solid support can include various metal salts, metalloid oxides, and/or metal oxides, e.g., titania (titanium oxide), zirconia (zirconium oxide), silica (silicon oxide), alumina (aluminum oxide), magnesia (magnesium oxide), and magnesium chloride. In certain embodiments, the solid support can include alumina (A1₂0₃), silica (Si0₂), magnesia (MgO), titania (Ti0₂), zirconia (Zr0₂), cerium(IV) oxide (Ce0₂), or a combination thereof. The amount of the solid support present in the catalyst can be between about 40% and about 95%, by weight, relative to the total weight of the catalyst. By way of non-limiting example, the solid support can constitute about 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% of the total weight of the catalyst.

[0030] In certain embodiments, the catalyst can include one or more additional metals in addition to Cu and Mn. The additional metal(s) can include lanthanum (La), calcium (Ca), potassium (K), tungsten (W), and/or aluminum (Al). In certain embodiments, the additional metal(s) can be present in an amount between about 1% and 25%, relative to the total weight of the catalyst. For example, the catalyst can include about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 18%, 20%, 22%, or 25% of the additional metal(s), by weight.

[0031] In certain embodiments, the catalyst can include about 1% to about 25% Cu, by weight. For example, the catalyst can include about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 18%, 20%, 22%, or 25% Cu, by weight. In certain embodiments, the catalyst can include about 1% to about 25% Mn, by weight. For example, the catalyst can include about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 18%, 20%, 22%, or 25% Mn, by weight. In certain embodiments, the catalyst can include about 10% Cu and about 10% Mn, by weight. The remainder of the catalyst can be oxygen (i.e., the oxygen present in a metal oxide) and solid support (e.g., A1₂0₃).

[0032] Catalysts that include Cu and Mn can include Cu and Mn in various oxidation states. For example, Cu can be present in the catalyst as Cu(I) oxide (Cu₂0) and/or Cu(II) oxide (CuO). For example, Mn can be present in the catalyst as oxide (MnO). In certain embodiments, higher oxides of Mn initially present in the catalyst can be reduced in situ in the presence of H₂.

[0033] The catalysts of the presently disclosed subject matter can be prepared according to various techniques known in the art. For example, metal oxide catalysts suitable for use in RWGS reactions can be prepared from various metal nitrates, metal halides, metal salts of organic acids, metal hydroxides, metal carbonates, metal oxyhalides, metal sulfates, and the like. In certain embodiments, a transition metal oxide (e.g., a Cu or Mn oxide, or a mixed Cu/Mn oxide) can be precipitated along with a solid support (e.g., A1₂0₃). In certain embodiments, and as exemplified in the Examples below, catalysts can be prepared by precipitation of metal nitrates.

Reaction Mixtures

[0034] The presently disclosed subject matter provides methods of converting mixtures of H₂ and C0₂ into syngas via the reverse water gas shift (RWGS) reaction. A mixture of H₂ and C0₂ can be termed a "reaction mixture." The mixture of H₂ and C0₂ can alternatively be termed a "feed mixture" or "feed gas."

[0035] The C0₂ in the reaction mixture can be derived from various sources. In certain embodiments, the C0₂ can be a waste product from an industrial process. In certain embodiments, C0₂ that remains unreacted in the RWGS reaction can be recovered and recycled back into the RWGS reaction.

[0036] Reaction mixtures suitable for use with the presently disclosed methods can include various proportions of H₂ and C0₂. In certain embodiments, the reaction mixture can include H₂ and C0₂ in a molar ratio (H₂:C0₂) between about 5:1 and about 1:2, e.g., about 5:1, 4:1, 3:1, 2.8:1, 2.6:1, 2.5:1, 2.4:1, 2.3:1, 2.2:1, 2.1:1, 2:1, 1.9:1, 1.8:1, 1.7:1, 1.6:1, 1.5:1, 1.4:1, 1.3:1, 1.2:1, 1.1:1, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2. The reaction mixture can include H₂ and C0₂ in a molar ratio (H₂:C0₂) of about 2:1 to about 1:1. In certain embodiments, the reaction mixture can include H₂ and C0₂ in a molar ratio (H₂:C0₂)of about 1.5:1.

Methods of Preparing Syngas and Light Olefins

[0037] The methods of the presently disclosed subject matter include methods of preparing syngas. In one embodiment, an exemplary method can include providing a reaction chamber, as described above. The reaction chamber can include a solid-supported catalyst, as described above. The method can further include feeding a reaction mixture, as described above, to the reaction chamber. The method can additionally include contacting H₂ and C0₂ (present in the reaction mixture) with the catalyst at a reaction temperature greater than or equal to about 800 °C, thereby inducing a RWGS reaction to provide a product mixture that includes H₂ and CO. The product mixture can further include H₂0 (a product of the RWGS reaction, as shown in Equation 1) and unreacted C0₂.

[0038] The reaction mixture can be fed into the reaction chamber at various flow rates. The flow rate and gas hourly space velocity (GHSV) can be varied, as is known in the art. In certain embodiments, the flow rate can be about 5 to about 50 cc/min. In certain embodiments, the flow rate can be about 10 to about 25 cc/min. In certain embodiments, the flow rate can be about 15 cc/min. In certain embodiments, the flow rate can be about 22.5 cc/min.

[0039] The reaction temperature can be understood to be the temperature within the reaction chamber. The reaction temperature can influence the RWGS reaction, including conversion of C0₂ and H₂, the ratio of H₂:CO in the product mixture, and the overall yield. In certain embodiments, the reaction temperature can be greater than or equal to about 750 °C, e.g., greater than or equal to about 760 °C, 770 °C, 780 °C, 790 °C, 800 °C, 810 °C, 820 °C, 830 °C, 840 °C, or 850 °C. In certain embodiments, the reaction temperature can be greater than or equal to about 800 °C, e.g., greater than or equal to about 810 °C, 820 °C, 830 °C, 840 °C, or 850 °C. In certain embodiments, the reaction temperature can be between about 900 °C and about 700 °C. In certain embodiments, the reaction temperature can be about 800 °C. In certain embodiments, the reaction temperature can be about 850 °C.

[0040] The RWGS can proceed with partial conversion of C0₂ and H₂, thus providing a product mixture that includes CO, H₂0, C0₂, and H₂. In certain embodiments, the RWGS reaction can be performed from about 50% to about 70% conversion of C0₂. In certain embodiments, the RWGS reaction can be performed to about 70% conversion of C0₂. In certain embodiments, the RWGS reaction can be performed to about 65.3% conversion of C0₂. In certain embodiments, the RWGS reaction can be performed to about 68% conversion of C0₂. Adjustment of the degree of conversion of C0₂ and H₂ as well as adjustment of the ratio of C0₂ and H₂ in the reaction mixture can therefore influence the ratio of H₂ and CO in the syngas product formed. For example, use of a higher molar ratio of H₂:C0₂ in the reaction mixture can increase the molar ratio of H₂:CO in the product mixture.

[0041] In certain embodiments, the product mixture can include H₂ and CO in a molar ratio (H₂:CO) of about 0.5: 1 to about 5: 1. In certain embodiments, the product mixture can include H₂ and CO in a molar ratio (H₂:CO) of about 1 : 1 to about 3 : 1, e.g., about 1 : 1, 1.1 : 1, 1.2: 1, 1.3 : 1, 1.4: 1, 1.5 : 1, 1.6: 1, 1.7: 1, 1.8: 1, 1.9: 1, 2: 1, 2.1 : 1, 2.2: 1, 2.3 : 1, 2.4: 1, 2.5 : 1, 2.6: 1, 2.7: 1, 2.8: 1, 2.9: 1, or 3 : 1. In certain embodiments, the product mixture can include H₂ and CO in a molar ratio (H₂:CO) of about 1.5 : 1 to about 3 : 1, about 2: 1 to about 3 : 1, about 2.36: 1 or about 2.26: 1. As noted above, the molar ratio (H₂:CO) of the product mixture can be influenced by the molar ratio (H₂:C0₂) of the reaction mixture.

[0042] In certain embodiments, the RWGS can be performed to relatively high conversion. That is, the amount of C0₂ present in the product mixture can be relatively low. In certain embodiments, the product mixture can include less than about 25% C0₂, by mole or less than about 20%) C0₂, by mole. For example, the product mixture can include about 24%>, 23%>, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 1 1%, 10%, 9%, 8% by mole. In certain embodiments, the product mixture can include about 13.6% C0₂ by mole. In certain embodiments, the product mixture can include about 12.5% C0₂ by mole.

[0043] In certain embodiments, the methods of the presently disclosed subject matter can include separating at least a portion of C0₂ and/or H₂0 from the product mixture, to provide purified syngas. C0₂ and/or H₂0 can be separated by various techniques known in the art. By way of non-limiting example, H₂0 can be separated by condensation, e.g. , by cooling the product mixture. In certain embodiments, C0₂ can be removed from the product mixture and contributed to the reaction mixture, thereby recycling C0₂ through the RWGS reaction and improving overall economy of the process.

[0044] The presently disclosed subject matter also provides methods of preparing light olefins. In one embodiment, an exemplary method of preparing light olefins can include conducting a RWGS reaction to convert C0₂ and H₂ into a product mixture that includes H₂, CO, C0₂, and H₂0, as described above. The method can additionally include separating at least a portion of C0₂ and H₂0 from the product mixture, to provide purified syngas. The method can further include subjecting purified syngas to a Fischer-Tropsch synthesis (FT) reaction to provide light olefins.

[0045] For the purpose of illustration and not limitation, FIG. 1 is a schematic representation of an exemplary process 100 according to the disclosed subject matter. In certain embodiments, a RWGS reaction 102 can be integrated with a FT reaction 105. As shown in FIG. 1, C0₂ 107 can be removed from the product mixture 103 obtained from a RWGS mixture to provide syngas, and the syngas can be fed into a FT reaction 105. C0₂ and products can optionally be separated from the product mixture 106 from the FT reaction in the same separation unit 103.

[0046] In certain embodiments, the process 200 can include separating water and C0₂ 203 from the product mixture from the RWGS reaction 202. As shown in FIG. 2, C0₂ 208 can optionally be separated from and recycled back into the RWGS reaction 201. Products 205 from the FT reaction 204 can also be separated 207 into hydrocarbons 206 and C0₂209. The C0₂ 209 from this reaction can also be recycled back into the RWGS reaction 201.

[0047] In certain alternative embodiments, as shown in FIG. 3, the product mixture from the RWGS reaction 302 can be fed directly into the FT reaction 304 without removal of C0₂. In certain embodiments, FT catalysts can tolerate the presence of C0₂, and C0₂ itself can participate in FT-type reactions. As shown in FIG. 3, products from the FT reaction can also be separated 305 into hydrocarbons 306 and C0₂. The C0₂ 307 from this reaction can then be recycled back into the RWGS reaction 301.

[0048] The methods of the presently disclosed subject matter can have advantages over other techniques for preparation of syngas and preparation of light olefins. The presently disclosed subject matter includes the surprising discovery that catalysts containing Cu and/or Mn can be used to promote RWGS reactions at temperatures greater than or equal to about 800 °C without sacrificing product purity or catalyst stability. [0049] Additional advantages of the presently disclosed subject matter can include preparation of syngas with improved H₂:CO ratios. As demonstrated in the Examples, the methods of the presently disclosed subject matter can provide syngas containing H₂ and CO in a molar ratio of about 2: 1 (e.g., 2.26: 1), suitable for use in FT reactions. Moreover, the methods of the presently disclosed subject matter can prepare syngas via hydrogenation of C0₂ with minimal side reactions, good catalyst stability, good conversion of C0₂ (e.g., greater than 50%), and good yields of syngas. Additional advantages of the presently disclosed subject matter can include improved energy efficiency and overall economy.

EXAMPLES

[0001] The following examples are merely illustrative of the presently disclosed subject matter and should not be considered as limiting in any way.

EXAMPLE 1 - Preparation of Catalyst

[0050] This Example describes the preparation of a Cu-Mn-Al catalyst.

[0051] The nitrate salts of Cu(N0₃)₂, Mn(N0₃)₂ and A1(N0₃)₃ were dissolved in 200 ml of water. H₄OH was added drop wise until the pH of the mixture was about 8. The precipitate was washed and filtrated. The mass after filtration was dried for 12 hours at 120°C and then calcined for 8 hours at 650°C. The catalyst composition after calcination contained 10%Cu and 10%Mn (both weight % ) on A1₂0₃.

EXAMPLE 2 - Hydrogenation at 800°C

[0052] This Example describes C0₂ hydrogenation with a Cu-Mn-Al catalyst.

[0053] C0₂ was hydrogenated by H₂ at 800°C in the presence of pellets of 10%Cu- 10%Mn/Al₂O₃ catalyst. The pellets were prepared by pelletizing precipitated, dried gel of Cu-Mn-Al metals. The catalyst loading was 8.4g. The flow rates of hydrogen and C0₂ were H₂ at 22.5 cc/min and C0₂ at 15 cc/min. The outlet gas composition after the reaction and after the separation of water is summarized in Table 1. Table 1. Outlet gas composition (% mol)

EXAMPLE 3 - Hydrogenation at 850°C

[0054] This Example describes C0₂ hydrogenation with a Cu-Mn-Al catalyst at a reaction temperature of 850°C.

[0055] C0₂ was hydrogenated by H₂ at 850°C in the presence of 10%Cu-10%Mn/Al₂O₃ catalyst pellets impregnated on A1₂0₃. The catalyst loading was 8.4g. The flow rates of hydrogen and C0₂ were H₂ at 22.5cc/min and C0₂ at 15 cc/min. The outlet gas composition, after, separation of water is summarized in Table 2.

Table 2. Outlet gas composition (% mol)

EXAMPLE 4 - Olefin synthesis

[0056] The hydrogenation products of Examples 2 or 3 are mixed with the FT reaction products and separated. EXAMPLE 5 - Separation of products

[0057] The hydrogenation products of Examples 2 or 3 are separated from C0₂, separate of FT reaction products. In this case, separation cost is decreased due to the low concentration of C0₂ (not more than 13%).

EXAMPLE 6 - Separation of products

[0058] Unconverted C0₂ in the hydrogenation products of Examples 2 or 3 is not separated from hydrogenation products. The unconverted C0₂ is used as a feed for FT reactions.

EXAMPLE 7 - Evidence of Catalyst Stability

[0059] The catalysts used in Examples 2-3 were tested for 60 days. During this time, there was no observable change in catalyst activity, evidencing the stability of the catalysts under the reaction conditions.

* * *

[0060] Although the presently disclosed subject matter and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosed subject matter as defined by the appended claims. Moreover, the scope of the disclosed subject matter is not intended to be limited to the particular embodiments described in the specification. Accordingly, the appended claims are intended to include within their scope such alternatives.

Claims

1. A method of preparing syngas, comprising:

a. providing a reaction chamber that comprises a catalyst comprising Cu and Mn; b. feeding a reaction mixture comprising H₂ and C0₂ to the reaction chamber; and

c. contacting H₂ and C0₂ with the catalyst at a reaction temperature greater than 800 °C to provide a product mixture that comprises H₂ and CO.

2. The method of claim 1, wherein the catalyst comprises Cu and Mn in a molar ratio of about 4: 1 to about 1 :4.

3. The method of claim 2, wherein the catalyst comprises Cu and Mn in a molar ratio of about 1 : 1.

4. The method of claim 1, wherein the catalyst further comprises one or more solid

supports selected from the group consisting of A1₂0₃, MgO, Si0₂, Ti0₂, and Zr0₂.

5. The method of claim 1, wherein the catalyst comprises one or more additional metals selected from the group consisting of La, Ca, K, W, and Al.

6. The method of claim 5, wherein the catalyst comprises Al.

7. The method of claim 1, wherein the catalyst comprises about 10% Cu and about 10% Mn, by weight.

8. The method of claim 1, wherein the reaction mixture comprises H₂ and C0₂ in a

molar ratio (H₂:C0₂) of about 1.5: 1.

9. The method of claim 1, wherein the reaction temperature is greater than about 800 °C.

10. The method of claim 9, wherein the reaction temperature is greater than about 825 °C.

11. The method of claim 10, wherein the reaction temperature is about 850 °C.

12. The method of claim 1, wherein the product mixture comprises H₂ and CO in a molar ratio (H₂:CO) of about 1 : 1 to about 3 : 1.

13. The method of claim 12, wherein the product mixture comprises H₂ and CO in a molar ratio (H₂:CO) of about 1.5 : 1 to about 3 : 1.

14. The method of claim 13, wherein the product mixture comprises H₂ and CO in a

molar ratio (H₂:CO) of about 2: 1 to about 3 : 1.

15. The method of claim 13, wherein the product mixture comprises H₂ and CO in a

molar ratio (H₂:CO) of about 2.26: 1 to about 2.36: 1.

16. The method of claim 1, wherein the product mixture further comprises C0₂ and H₂0.

17. The method of claim 16, wherein the product mixture comprises less than about 25% C0₂, by mole.

18. The method of claim 17, wherein the product mixture comprises less than about 15% C0₂, by mole.

19. The method of claim 16, further comprising separating at least a portion of C0₂ and H₂0 from the product mixture to provide purified syngas.

20. A method of preparing light olefins, the method comprising:

a. providing a reaction chamber that comprises a solid-supported catalyst

comprising Cu and Mn;

b. feeding a reaction mixture comprising H₂ and C0₂ to the reaction chamber; c. contacting H₂ and C0₂ with the catalyst at a reaction temperature greater than or equal to about 800 °C to provide a product mixture that comprises H₂, CO, C0₂, and H₂0;

d. separating at least a portion H₂0 from the product mixture; and

e. subjecting the product mixture to a Fischer-Tropsch synthesis (FT) reaction to provide light olefins.