CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 62/456,362, filed February 8, 2018 and is incorporated by reference herein in its entirety without disclaimer.

BACKGROUND OF THE INVENTION

A. Field of the Invention

[0002] The invention generally concerns a three-dimensional (3-D) structured monolith catalyst having a 3-D structured support material and a catalytically active metal sulfide or metal oxy sulfide, method of producing the catalyst and methods of using the catalyst for the conversion of carbon dioxide gas (C0 ₂ (g)) and elemental sulfur gas (S(g)) to carbon monoxide gas (CO(g)) and sulfur dioxide gas (S0 ₂ (g)).

B. Description of Related Art

[0003] Conventional heterogeneous catalysts can include active metals supported on inert or acidic/basic support materials possessing a 3-D structure. These catalysts can be prepared by extrusion or pelletizing, and are often highly dense in order to provide good mechanical strength. One of the drawbacks of using highly dense 3-D support materials is that the bulk of the catalyst (i.e., the support) is not accessible, and consequently, not catalytic. Moreover, at high temperatures a loss in mechanical strength of the support material can occur, thereby resulting in the increased production of fine powder. By way of example, in high temperature heterogeneous catalysis applications (e.g., > 600 °C), the active metal, metal oxide supports, and metal sulfide supports can undergo sintering. Sintering can result in a decrease in active surface area and catalytic activity. Sintering can also lead to catalyst attrition, followed by powder formation, and, in some cases, breakage of pellets and extrudates can take place, resulting in more powder formation. The resulting powder can accumulate in the reactor, affecting downstream processes and/or decrease reactor pressure.

[0004] One attempt to overcome the reaction pressure drop issue includes the introduction of ceramic monoliths to the reaction, especially in selective catalytic reduction (SCR) catalysts for mobile applications. Many of these include catalytically inert metallic monoliths having catalytically active metal species coated on the inert metallic monolith surface. By way of example, Wang et al., (Carbon, 2014, 76(2), p. 471) describes 3D-MoS ₂ -graphene hybrid monoliths prepared by a combined hydrothermal self-assembly and freeze-drying treatment using a graphite monolith. U.S. Patent Application Publication No. 2016/0107893 to D-Souza et al., describes a method to convert CO2 to CO using a metal oxide or sulfide catalyst. The catalysts included bulk metal oxide or sulfides supported on a metal sulfide, nitride, and/or phosphate support. In another example, U.S. Patent No. 5,911,964 to Iwanami et al., describes a process to reduce carbon dioxide employing a catalyst which contains at least one transition metal selected from the group consisting of Group VIII and Group VIA on zinc oxide alone or on a composite containing zinc oxide and at least one metal oxide of a metal selected from the group consisting of Group IIIB and Group IVA. [0005] Despite all of the currently available research focused on the development of heterogeneous catalysts, many of these catalysts including inert monolithic ceramic or metal supports can possess poor mechanical strength, poor high temperature performance, and can be difficult to apply in larger installations for immobile applications.

SUMMARY OF THE INVENTION [0006] A solution to the problems associated with heterogeneous catalysts used to catalyze the conversion of carbon dioxide gas (C0 ₂ (g)) and elemental sulfur gas (S(g)) to produce carbon monoxide gas (CO(g)) and sulfur dioxide gas (S0 ₂ (g)) has been discovered. The solution resides in the ability to prepare a three-dimensional (3-D) structured monolith catalyst having a 3-D structured support material and a catalytically active metal sulfide or metal oxysulfide. Notably, the current invention provides catalytic material including metal oxide or metal sulfide coated and/or deposited onto monolithic 3-D structures by slip casting, dip coating, spray coating, pressure deposition, vacuum deposition, pore-filling, or 3-D printing.

[0007] The current invention provides a catalyst with many beneficial properties. A few of these beneficial properties can include, but are not limited to: pressure drop across catalysts beds; low thermal expansion coefficient to increase thermal shock resistance; porosity and pore size distribution suitable to improve wash-coat application and adherence; high melting point {e.g., exceeding 1450 °C) to promote refractoriness; and increased strength for high temperature applications. Furthermore for diffusion driven reactions, the combination of high cell density (e.g., 31-186 cells/cm ² or 200-1200 cells/inch ² ) with thin walls (e.g., 0.051-0.27 mm or 0.002-0.0105 inch) can lower backpressure and contact time to decrease the formation of side products. [0008] In one particular embodiment, a method of producing carbon monoxide (CO) and sulfur dioxide (SO2) is described. The method can include obtaining a 3-D structured monolith catalyst. The 3-D structured monolith catalyst can include a 3-D structured support material and a catalytically active material. The 3-D structured monolith can be contacted with a reaction mixture that include carbon dioxide gas (C0 ₂ (g)) and elemental sulfur gas (S(g)) under reaction conditions sufficient to produce a product stream comprising CO(g) and S0 ₂ (g). In one aspect, the reaction conditions can include a reaction pressure of 1 to 50 bar, a reaction temperature of 250 °C to 3000 °C, or a gas hourly space velocity (GHSV) of 100 to 100,000 h ^"1 , or any combination or all thereof. In another aspect, the 3-D structured monolith catalyst can include a sulfurized outer surface. In other aspects, the structure of the 3-D structured monolith catalyst can include a honeycomb, plate, corrugated, foam, or mesh. When the structure of the 3-D structured monolith includes a honeycomb monolith, it can include an open flow ceramic honeycomb, wall-flow honeycomb, or metal honeycomb structure. The support material can also include a honeycomb structure that is further defined by including at least one of: a hole number from 25 to 1600 cells per square inch; a cross section of 150 mm x 150 mm; a hole diameter from 2.0 to 9.0 mm; a wall thickness from 0.5 to 1.4 mm; a catalyst pitch from 10.0 to 2.5 mm; an open porosity from 60 to 75%, and a specific surface area from 10 to 1300 m ² /g. In some instances, the 3-D structured monolith catalyst can include a channel of a length that is 10 to 10000 times a diameter of the channel. In other instances, the support material can include a metal, ceramic, and/or glass material. In a particular aspect, the support material can include at least one of molybdenum oxide (M0O2), tungsten oxide (WO3), vanadium oxide (V2O5), titanium oxide (T1O2), silicon carbide (SiC), aluminum nitride (A1N), silicon nitride (SiN), aluminum titanium oxide (AIT1O5), a sintered metal, alumina, cordierite, mullite, pollucite, or thermet. The catalytically active material of the 3-D structured monolith catalyst of the present invention can include at least one metal, metal oxide, metal sulfide, metal oxysulfide, lanthanide, lanthanide oxide, olivine, perovskite, chalcogenide, silicate, sulfate, zincite group oxide (XO), rutile group oxide (XO2), spinel group oxide (XY2O4), or hydroxide group oxide, where X and Y are metals. In some aspects, the catalytically active material can be a metal, metal oxide, or metal sulfide of the alkaline earth metals (Column 2), transition metals (Columns 3-12), and post transition metals (Columns 13-16). In certain aspects, the catalytically active material can be a metal sulfide. In other aspects, the catalytically active material can be a lanthanide or lanthanide oxide including at least one of lanthanum (La), cerium (Ce), Dysprosium (Dy), thulium (Tm), ytterbium (Yb), lutetium (Lu), ceria (Ce0 ₂ ), dysprosium oxide (Dy ₂ 0 ₃ ), thulium oxide (Ti Cb), ytterbium oxide (Yb ₂ 0 ₃ ), lutetium oxide (Lu ₂ 0 ₃ ), and lanthanum oxide (La ₂ 0 ₃ ).

[0009] In another embodiment, a three-dimensional (3-D) structured monolith catalyst including a 3-D structured support material and a catalytically active metal sulfide or metal oxysulfide is described. The catalyst can be used to catalyze a reaction mixture that can include carbon dioxide gas (C0 ₂ (g)) and elemental sulfur gas (S(g) to produce a product stream comprising CO(g) and S0 ₂ (g). In one aspect, the 3-D structured monolith catalyst can include a sulfurized outer surface. The structure of the 3-D structured monolith catalyst can include a honeycomb, plate, corrugated, foam, or mesh structure. When the structure of the 3-D structured monolith includes a honeycomb monolith, it can include an open flow ceramic honeycomb, wall-flow honeycomb, or metal honeycomb structure. In other aspects, the support material can include a honeycomb structure further defined as including at least one of a hole number from 25 to 1600 cells per square inch; a cross section of 150 mm x 150 mm; a hole diameter from 2.0 to 9.0 mm; a wall thickness from 0.5 to 1.4 mm; a catalyst pitch from 10.0 to 2.5 mm; an open porosity from 60 to 75%, and a specific surface area from 10 to 1300 m ² /g. In some instances, the 3-D structured monolith catalyst can include a channel of a length that is 10 to 10000 times a diameter of the channel. In other instances, the 3-D structured support material can include a metal, ceramic, and/or glass material. In a particular aspect, the 3-D structured support material can include at least one of W0 ₃ , V2O5, T1O2, SiC, A1N, SiN, AIT1O5, a sintered metal, alumina, cordierite, mullite, pollucite, or thermet. In some embodiments, the 3-D structured support material is coated with a metal oxide support material (e.g., alumina, silica, titania, zirconia, or mixtures thereof) between the 3-D structured material and the catalytically active material. This coating can assist in binding the catalytically active material to the 3-D structured support material. The catalytically active material of the 3-D structured monolith catalyst can include at least one metal, metal oxide, metal sulfide, lanthanide, lanthanide oxide, olivine, perovskite, chalcogenide, silicate, sulfate, zincite group oxide (XO), rutile group oxide (XO2), spinel group oxide (XY2O4), or hydroxide group oxide. The metal sulfide or metal oxysulfide can include an alkaline earth metal, a transition metal or a post transition metal of the periodic Table. Non-limiting examples of catalytic metals include metals from Columns 2-4, 6, or 8-12, of the Periodic Table. In further aspects, the catalytically active material can include at least one of La, Ce, Dy, Tm, Yb, and Lu.

[0010] Also disclosed is a method of making a 3-D structured monolith catalyst of the present invention. The method can include obtaining a support material and a catalytically active material that is able to catalyze a reaction mixture comprising carbon dioxide gas (C0 ₂ (g)) and elemental sulfur gas (S(g) to produce a product stream comprising CO(g) and S0 ₂ (g). The 3-D structured monolith catalyst that includes the active material and the support material can be produced from the support material and catalytically active material. In certain aspects, the catalytically active material can be coated onto a 3-D structured support material by a process that includes: obtaining a 3-D structured support material; obtaining a slurry that includes the catalytically active material; and contacting the 3-D structured support material with the slurry to obtain the 3-D structured monolith catalyst. In some aspects, a support material (e.g., gamma alumina, silica, titania, zirconia, or combinations thereof) can be coated on the 3-D structured support material and then the catalytically active metal can be coated on the coated 3-D structured support material. In one aspect, the slurry can include a protic solvent and a viscosity of 40 to 500 centipoise. In other aspects, the slurries can aqueous solutions of water and metal oxide(s) with optional binder. The slurry can be applied to the 3-D structured support material by slip casting, pore filling, dip coating, spray coating, pressure deposition, or vacuum deposition. In other aspects, the method can further include: mixing the support material with the catalytically active material in a paste; and extruding the paste through a die to form a 3-D structured monolith catalyst comprising the active material and the support material. In some instances, the paste can further include at least one binder and/or viscosity modifier. In other instances, the method can further include: obtaining a 3-D ink comprising the support material and the catalytically active material; and using the ink in a 3-D printing process to form a 3-D structured monolith catalyst that includes the active material and the support material. The ink can include an oxide support material, a catalytically active metal oxide, and a viscosity modifier.

[0011] Other embodiments of the invention are described throughout this application. Any embodiment discussed with respect to one aspect of the invention applies to other aspects of the invention as well and vice versa. Each embodiment described herein is understood to be embodiments of the invention that are applicable to all aspects of the invention. It is contemplated that any embodiment discussed herein can be implemented with respect to any method or composition of the invention, and vice versa. Furthermore, compositions the invention can be used to achieve methods of the invention.

[0012] The following includes definitions of various terms and phrases used throughout this specification. [0013] The term "monolith" is intended to include a porous, three-dimensional ceramic or metallic material having a continuous interconnected pore structure.

[0014] The term "catalyst" means a substance, which alters the rate of a chemical reaction. "Catalytic" or "catalytic active" means having the properties of a catalyst. [0015] The term "inert" means a substance, which does not participate in any chemical reaction described throughout the specification.

[0016] The term "about" or "approximately" are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, the terms are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0017] The term "substantially" and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0018] The terms "inhibiting" or "reducing" or "preventing" or "avoiding" or any variation of these terms, when used in the claims and/or the specification includes any measurable decrease or complete inhibition to achieve a desired result.

[0019] The terms "wt.%", "vol.%", or "mol.%" refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a non-limiting example, 10 grams of component in 100 grams of the material is 10 wt.%) of component.

[0020] The term "effective," as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

[0021] The use of the words "a" or "an" when used in conjunction with any of the terms "comprising," "including," "containing," or "having" in the claims or the specification may mean "one," but it is also consistent with the meaning of "one or more," "at least one," and "one or more than one."

[0022] The words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include") or "containing" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. [0023] The three-dimensional (3-D) structured monolith catalyst of the present invention and methods of use can "comprise," "consist essentially of," or "consist of particular ingredients, components, compositions, etc. disclosed throughout the specification. With respect to the transitional phase "consisting essentially of," in one non-limiting aspect, a basic and novel characteristic of the 3-D structured monolith catalysts is their ability to catalyst a CO2 and S2 reaction to produce CO and SO2.

[0024] In one aspect of the present invention 20 embodiments are described. Embodiment 1 is a method of producing carbon monoxide (CO) and sulfur dioxide (SO2), the method comprising: obtaining a 3-D structured monolith catalyst comprising a 3-D structured support material and a catalytically active material; and contacting the 3-D structured monolith with a reaction mixture comprising carbon dioxide gas (C02(g)) and elemental sulfur gas (S(g)) under reaction conditions sufficient to produce a product stream comprising CO(g) and S02(g). Embodiment 2 is the method of embodiment 1, wherein the reaction conditions comprise a reaction pressure of 1 to 50 bar, a reaction temperature of 250 °C to 3000 °C, or a gas hourly space velocity (GHSV) of 100 to 100,000 h ^"1 , or any combination or all thereof. Embodiment 3 is the method of any one of embodiments 1 to 2, wherein the 3-D structured monolith catalyst comprises a sulfurized outer surface. Embodiment 4 is the method of any one of embodiment 1 to 3, wherein the 3-D structured monolith catalyst comprises a honeycomb, plate, corrugated, foam, or mesh structure, preferably an open flow ceramic honeycomb, wall-flow honeycomb, or metal honeycomb structure. Embodiment 5 is the method of any one of embodiments 1 to 4, wherein the support material comprises a honeycomb structure further defined as comprising at least one of: a hole number from 25 to 1600 cells per square inch; a cross section of 150 mm x 150 mm; a hole diameter from 2.0 to 9.0 mm; a wall thickness from 0.5 to 1.4 mm; a catalyst pitch from 10.0 to 2.5 mm; an open porosity from 60 to 75%, and a specific surface area from 10 to 1300 m ² /g. Embodiment 6 is the method of any one of embodiments 1 to 5, wherein the 3-D structured monolith catalyst comprises a channel of a length that is 10 to 10000 times a diameter of the channel. Embodiment 7 is the method of any one of embodiments 1 to 6, wherein the support material comprises a metal, ceramic, and/or glass material.

[0025] Embodiment 8 is a three-dimensional (3-D) structured monolith catalyst comprising a 3-D structured support material and a catalytically active metal sulfide or metal oxy sulfide that is able to catalyze a reaction mixture comprising carbon dioxide gas (C02(g)) and elemental sulfur gas (S(g) to produce a product stream comprising CO(g) and S02(g). Embodiment 9 is the three-dimensional (3-D) structured monolith catalyst of embodiment 8, wherein the 3-D structured monolith catalyst comprises a sulfurized outer surface. Embodiment 10 is the 3-D structured monolith catalyst of any one of embodiments 8 to 9, comprising a honeycomb, plate, corrugated, foam, or mesh structure. Embodiment 11 is the 3- D structured monolith catalyst of any one of embodiments 8 to 10, further defined as a honeycomb monolith comprising an open flow ceramic honeycomb, wall-flow honeycomb, or metal honeycomb. Embodiment 12 is the 3-D structured monolith catalyst of any one of embodiments 8 to 11, wherein the support material comprises a honeycomb structure further defined as comprising at least one of: a hole number from 25 to 1600 cells per square inch; a cross section of 150 mm x 150 mm; a hole diameter from 2.0 to 9.0 mm; a wall thickness from 0.5 to 1.4 mm; a catalyst pitch from 10.0 to 2.5 mm; an open porosity from 60 to 75%, and a specific surface area from 10 to 1300 m ² /g. Embodiment 13 is Tthe 3-D structured monolith catalyst of any one of embodiments 8 to 12, comprising a channel of a length that is 10 to 10000 times a diameter of the channel. Embodiment 14 is the 3-D structured monolith catalyst of any one of embodiments 8 to 13, wherein the support material comprises a metal, ceramic, and/or glass material. Embodiment 15 is the 3-D structured monolith catalyst of any one of embodiments 8 to 14, wherein the support material comprises at least one of WCb, V2O5, T1O2, SiC, A1N, SiN, AIT1O5, a sintered metal, alumina, cordierite, mullite, pollucite, or thermet, or a coating of alumina on the support material. Embodiment 16 is the 3-D structured monolith catalyst of any one of embodiments 8 to 15, wherein the catalytically active material comprises at least one metal, metal oxide, metal sulfide, lanthanide, lanthanide oxide, olivine, perovskite, chalcogenide, silicate, sulfate, zincite group oxide (XO), rutile group oxide (XO2), spinel group oxide (XY2O4), or hydroxide group oxide, where X and Y are metals. Embodiment 17 is the 3-D structured monolith catalyst of any one of embodiments 8 to 16, wherein the metal sulfide or metal oxysulfide comprises a alkaline earth metal, a transition metal or a post transition metal. Embodiment 18 is the 3-D structured monolith catalyst of any one of embodiments 8 to 17, wherein the catalytically active material comprises at least one of La, Ce, Dy, Tm, Yb, Lu. Embodiment 19 is a method of making a 3-D structured monolith catalyst of any one of claims 8 to 18, the method comprising: obtaining a support material; obtaining a catalytically active material that is able to catalyze a reaction mixture comprising carbon dioxide gas (CC"2(g)) and elemental sulfur gas (S(g) to produce a product stream comprising CO(g) and SC"2(g); and producing a 3-D structured monolith catalyst comprising the active material and the support material. Embodiment 20 is the method of embodiment 19, further comprising (i) obtaining a 3-D structured support material; (ii) coating the 3-D structured support material with a slurry comprising a particulate support material and a binder; (iii) heat-treating the step (ii) coated 3- D structured support material; (iv) contacting the step (iii) coated 3-D structured support material with a slurry comprising a catalytically active metal to form a catalytically active layer on the coated 3-D structured support material; and (v) heat-treating the step (iv) catalytically active metal coated 3-D structured support material to produce the 3-D structured monolith catalyst.

[0026] Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings. [0028] FIG. 1 is an illustration of a generic 3-D honeycomb structure.

[0029] FIG. 2A is an illustration showing a cross-section of an outer surface of a 3-D monolith catalyst of the present invention having a single sulfide or oxysulfide phase layer...

[0030] FIG. 2B is an illustration showing a cross-section of an outer surface of a 3-D monolith catalyst of the present invention having a single sulfide or oxysulfide phase layer, and a coating layer below the single catalytically active layer.

[0031] FIG. 3 is an illustration showing a cross-section of an outer surface of a 3-D monolith catalyst of the present invention having two separate sulfide and/or oxysulfide phase layers.

[0032] FIG. 4 is an illustration showing a cross-section of an outer surface of a 3-D monolith catalyst of the present invention having three separate sulfide and/or oxysulfide phase layers. [0033] FIG. 5 is an illustration showing a cross-section of a 3-D honeycomb monolith catalyst of the present invention having a uniform deposited wash-coat.

[0034] FIG. 6 is a schematic illustration of a system to prepare carbon monoxide (CO) and sulfur dioxide (SO2) using the 3-D honeycomb monolith catalyst in one embodiment of the present invention.

[0035] FIGS. 7A-7D are scanning electron microscopy (SEM) micrographs of the catalytic monoliths having about 8 wt.% loading of M0O2 on a AI2O3 support coated on the 3-D structured monolith support at magnifications of: (7 A) 120 x; (7B) 250 x; (7C) 800 x; (7D); 3.5 x. [0036] FIGS. 8A-8D are SEM micrographs of the catalytic monoliths having about 12 wt.% loading of M0O2 on a AI2O3 support coated on the 3-D structured monolith support at magnifications of: (7 A) 120 x; (7B) 250 x; (7C) 350 x; (7D); 1000 x.

[0037] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0038] Disclosed is the preparation of three-dimensional (3-D) structured monolith catalysts having a 3-D structured support material and a catalytically active metal sulfide or metal oxysulfide and their use for the conversion of C02(g) and S(g) to produce gaseous CO and gaseous SO2. The catalytic material can be coated and/or deposited onto the monolithic 3- D structures by slip casting, pore filling, dip coating, spray coating, pressure deposition, vacuum deposition, or 3-D printing.

[0039] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections with reference to the Figures. A. 3-D Structured Monolith Catalysts

[0040] The catalysts of the present invention can include a 3-D structured monolith support material and a catalytically active metal sulfide or metal oxysulfide.

1. 3-D Structured Support Material

[0041] The three-dimensional (3-D) structured monolith catalysts of the present invention can have a 3-D structured support material. The support material can be chosen to contain increased empty space (e.g., having high porosity or hollowness) to increase surface area and enhance surface to volume ratios. Increasing the empty space of the support material can also advantageously reduce the weight of the catalyst to increase productivity and mass transfer limitations. The 3-D structure will typically contain a large number of straight and parallel channels that extend throughout the body of the structure. In one embodiment, the 3-D structured support material can have a honeycomb, plate, corrugated, foam, or mesh structure. The channel or pore shape can be triangular, square, rectangular, rhombic, pentagonal, hexagonal, or any polygonal shape, or mixtures thereof. FIG. 1 illustrates generic 3-D honeycomb structure 100. Without being limited by theory, the 3-D structured support material of the present invention can have mixtures of any of the above-mentioned a honeycomb, plate, corrugated, foam, or mesh structures in a 3-D structural arrangement. The 3-D structure support of the present invention can possess a high ratio of pressure drop to geometric surface area that can be highly beneficial during continuous flow catalysis applications.

[0042] In other embodiments, the 3-D support material includes a honeycomb structure that can include an open flow ceramic honeycomb, wall-flow honeycomb, or metal honeycomb structure. An open flow type honeycomb has a monolith body which includes repeating hexagonal unit cells where one or more of the hexagonal walls are opening to the adjoining hexagonal units. The openings can be continuous from cell to cell to form linear channels that traverse the direction of flow along the longitudinal axis of the hexagonal cell. A wall-flow type honeycomb structure has a monolith body which includes repeating hexagonal unit cells, where each hexagonal unit cell has inner cells and outer cells arranged in a hexagonal symmetry, and the inner cells are bordered by the outer cells and the outer cells are of diamond shape. Without being limited by theory, several important parameters can be used to define the honeycomb structure of the 3-D structured support material of the present invention. The honeycomb material can include a hole number from 25 to 1600 cells per square inch and all ranges and values there between (e.g., 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 1000, 100, 1200, 1300, 1400, or 1500 cells per square inch). The honeycomb material can include a cross section of 130 mm x 130 mm, 140 mm x 140 mm, 150 mm x 150 mm, 160 mm x 160 mm, 170 mm x 170 mm, preferably 150 mm x 150 mm. The honeycomb material can include a hole diameter from 2.0 to 9.0 mm and all ranges and values there between (e.g., 3.0, 4.0, 5.0, 6.0, 7.0, or 8.0 mm). The honeycomb material can include a wall thickness from 0.5 to 1.4 mm and all ranges and values there between (e.g., 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or 1.3 mm). The honeycomb material can include a catalyst pitch from 10.0 to 2.5 mm and all ranges and values there between (e.g., 9.0, 8.0, 7.0, 6.0, 5.0, 4.0, or 3.0 mm). The honeycomb material can include an open porosity from 60 to 75% and all ranges and values there between (e.g., 61, 62, 63, 64, 65, 66, 67, or 74%). The honeycomb material can include a specific surface area from 10 to 1300 m ² /g and all ranges and values there between (e.g., 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1 100, or 1200 m ² /g). In some instances, the 3- D structured support material can include a channel of a length that is 10 to 10000 times a diameter of the channel and all ranges and values there between (e.g., 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 4000, 5000, 6000, 7000, 8000, or 9000 times a diameter of the channel). [0043] In further embodiments, the 3-D structured support material used to prepare the 3- D structured monolith catalysts of the present invention can include a metal, ceramic, and/or glass material. In particular, the support material can include at least one of WCb, V2O5, T1O2, SiC, A1N, SiN, AIT1O5, a sintered metal, alumina, gamma alumina, cordierite, mullite, pollucite, or thermet. A non-limiting commercial source of materials used to form the 3-D structured support material of current invention includes Sigma- Aldrich®, (U. S.A.), Alfa Aesar (U.S.A.), and Fischer Scientific (U. S.A.).

2. Catalytic Material

[0044] The catalytically active material of the 3-D structured monolith catalyst of the present invention can include at least one metal, metal oxide, metal sulfide, metal oxysulfide, lanthanide, lanthanide oxide, olivine, perovskite, chalcogenide, silicate, sulfate, zincite group oxide (XO), rutile group oxide (XO2), spinel group oxide (XY2O4), or hydroxide group oxide. In some aspects, the catalytically active material can be a metal, metal oxide, or metal sulfide that includes a Columns 2-16 of the Periodic Table including the lanthanides. Non-limiting examples of the catalytically active material can include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), zirconium (Zr), vanadium (V), molybdenum (Mo), tungsten (W), iron (Fe), ruthenium (Ru), osmium (Os), cobalt, (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), tellurium (Te), or polonium (Po). Preferable metals include zirconium (Zr), vanadium (V), tungsten (W), manganese (Mn), rhenium (Rh), iron (Fe), cobalt (Co), nickel (Ni), or copper (Cu). In other aspects, the catalytically active material can be a lanthanide including lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), or lutetium (Lu). Preferably the catalytically active material is a lanthanide or lanthanide oxide including at least one of La, Ce, Dy, Tm, Yb, Lu, Ce0 ₂ , Dy ₂ 0 ₃ , Tm ₂ 0 ₃ , Yb ₂ 0 ₃ , Lu ₂ 0 ₃ , and La ₂ 0 ₃ . A non-limiting commercial source of the metals for use in the current invention includes Sigma- Aldrich®, (U.S.A.), Alfa Aesar (U.S.A.), and Fischer Scientific (U.S.A.).

[0045] In another embodiment, the catalytically active material can be coated and/or deposited onto monolithic 3-D structures by slip-casting, pore-filling, dip coating, spray coating, pressure deposition, vacuum deposition, or 3-D printing. In a particular aspect, the outer surface of the 3-D structured monolith catalyst of the present invention can include one or more sulfurized, oxidized, or oxysulfurized layers. FIGS. 2A, 2B, 3, and 4 depict variations of the layers. In the schematics, the monolith support is not shown. In a particular aspect, FIG. 2 A shows a schematic of an outer surface of a 3-D structured monolith catalyst 200 having a single sulfide or oxysulfide phase layer 202 on the active (catalytic) metal layer 204. FIG. 2B shows a schematic of an outer surface of a 3-D structured monolith catalyst 200 having a support coating 206, active (catalytic) metal layer 204 layer, and single sulfide or oxysulfide phase layer 202. FIG. 3 shows a schematic an outer surface of a 3-D structured monolith catalyst 300 having a first sulfide, oxidized, or oxysulfurized phase layer 202 and a second sulfide or oxysulfide phase layer 302 on the active metal layer 204. FIG. 4 shows a schematic of an outer surface of a 3-D structured monolith catalyst 400 of the present invention having an active metal layer 204, a first sulfide, oxide, or oxysulfide phase layer 202, a second sulfide, oxide, or oxysulfide phase layer 302, and a third sulfide or oxysulfide phase layer 402. In some instances, a support layer is added between the catalytic metal and the 3-D monolithic material (e.g., FIG. 2B), or between catalytic active materials. In certain aspects, the sulfurized outer layers of the present invention can be mixtures of sulfurized and oxidized metals or metal alloys that can be formed under subsequent coating or deposition conditions where the first sulfurization or oxidation conditions provide partial or incomplete sulfurization or oxidation or where coating or deposition occurs with previously coating or deposition surface metal or metal alloys. In some embodiments, further coating or deposition of metal or metal alloy catalysts can occur under substrate to product sulfurization reaction conditions, so that spent catalyst can be regenerated in situ to active catalyst to improve the efficiency of the overall catalytic process. The surface metals and alloy metals as well as metals and metal alloys below the surface of the 3-D catalyst can be sulfurized during the processes of the current invention. In particular instances, the morphology of the outer sulfide layer can include a flaky uneven structure, a well-defined defect free layer, or randomly oriented whiskers.

[0046] In particular embodiments, the 3-D structured monolith catalyst of the present invention has a low thermal expansion coefficient which reduces thermal shock and is stable (e-g; resist sintering) during high temperature catalytic applications. The catalyst can be partially, substantially, or completely sinter resistant at a range or specific reaction temperatures which also contributes to low pressure drop across catalyst beds during application. Exemplary reaction temperatures include where the catalyst of the present invention is partially, substantially, or completely sinter resistant includes 600 °C to 1500 °C and all value and ranges there between (e.g., 650, 700, 800, 850, 900, 950, 1000, 1050, 1 100, 1 150, 1200, 1250, 1300, 1350, 1400, or 1450 °C).

B. Method to Make the 3-D Structured Monolith Catalyst of the Present Invention

[0047] The catalysts of the current invention can be prepared by various methods. In some embodiments, a support material and/or a catalytically active material that is able to catalyze a reaction mixture comprising carbon dioxide gas (C0 ₂ (g)) and elemental sulfur gas (S(g) to produce a product stream that include CO(g) and S0 ₂ (g) can be obtained. From the support material and catalytically active material a 3-D structured monolith catalyst that includes the active material and the support material can be produced. In some embodiments, the 3-D monolith catalysts can be prepared by extrusion processes. By way of example, a metal oxide having low surface area can be extruded to form an extruded monolith. The extruded monolith can be coated with high surface area metal oxides either with or without catalytically active metals. When catalytically active metals are not used, separate impregnation steps including catalytically active metals can be performed. In another instance, if metal oxides having high surface area are used for the extrusion process the extruded monolith can be further impregnated with catalytically active metal or active metal precursors. In yet another instance, if metal oxides and catalytically active metals or active metal precursors are mixed and/or mulled together before extrusion the resultant extruded monolith can be directly used for catalytic applications. Since the current catalysts are intended for used in chemical process involving high reaction temperature, the success of these applications require a thermally stable and sinter resistant active catalytic matrix.

[0048] In one embodiment, the catalytically active material can be coated onto a 3-D structured support material (e.g., slip-casting or pore-filling). A non-limiting process can include obtaining a 3-D structured support material, and a slurry that includes the catalytically active material. The 3-D structured support material can be contacted with the slurry to obtain the 3-D structured monolith catalyst. In one aspect, the slurry can include a catalytically active material in a protic solvent or water. The slurry can be prepared by mixing catalytically active materials or precursors thereof with support materials and/or additives. In some embodiments, the 3-D structured support material is contacted with a metal oxide/binder solution, dried and then, contacted with slurry of catalytically active material. Additives can be included to achieve the physical properties required for a uniform deposition. A non-limiting example of an additive is a binder such as colloidal alumina (e.g., A10(OH and AI2O3). The protic solvent can include water and/or short chain alcohols, where the carbon count is less than about 20 carbons per hydroxyl. Non-limiting examples of short chain alcohols can include methanol, ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and t-butanol. The slurry can also contain a mixture of the catalytically active material of the present invention including a particulate catalyst support for example, but not limited to, alumina, an aluminum hydroxide compound (e.g., pseudobohemite alumina), lanthanum oxide, ceria, titania, zirconia, silica- alumina, zeolites, or combinations thereof, an inorganic acid, an organic acid for example, but not limited to, acetic acid, formic acid, citric acid, nitric acid, Tiron (i.e., disodium 4,5- dihydroxy-l,3-benzenedisulfonate), or combinations thereof, a thickener for example, but not limited to, silica sol, PEG, starch, polyvinyl alcohol, a stabilizing or templating agent for example, but not limited to, carboxymethyl cellulose (CMC), Triton X, or combinations thereof, and a surface modifier (e.g., ethyl acetate). In other aspects, the slurry can include a viscosity of 1 to 500 centipoise (cP), 4-11 cP, 50 to 300 cP, or preferably 60 to 100 cP and all ranges and values there between (e.g., 65, 70, 75, 80, 85, 90, or 95 cP).

[0049] The formed slurry can then be deposited on a 3-D structured support material of the present invention by known processes. Non-limiting examples of wash-coat deposition processes can include slip casting, pore-filling, dip coating, spray coating, pressure deposition, or vacuum deposition, or combinations thereof. In a wash-coat application the 3D-monolith can include suitable porosity and pore size distribution for ease of one or more wash-coat applications and increased wash-coat(s) adherence. FIG. 5 depicts a cross-section of a 3-D structured monolith catalyst 500 having a honeycomb structure 502 and uniform deposited wash-coat 504. In certain aspects, the weight loading of catalytic material from the slurry to monolith varies from 1/100 to 40/100. In a non-limiting example, the monolith catalyst can be prepared by coating a 3-D support material (e.g., a ceramic monolith material) using slip- casting techniques without filling the microcracks of the monolith so that the thermal shock properties that depend on the microcracks are retained. In slip-casting, a layer of support material covers the entirety of the structure of the monolith support. Coating can be performed by contacting the 3-D support material with a slurry of support material (e.g., metal oxide) and optional binder material. The slurry can include a mixture of support material (e.g., a metal oxide such as gamma- alumina) and binder (e.g., pseudobohemite alumina). The slurry can have a solids content of 50 wt.%, 30 wt.% to 45 wt.% or any value or range there between, or about 40 wt.%) with the metal oxide solids content being about 20 wt.%> to 50 wt.%, 30 wt.%> to 45 wt.%) or any value or range there between, or about 35 wt.%>. The optional binder content can be about 1 wt.%> to 10 wt.%, 2 wt.%> to 8 wt.%, 3 wt.%> to 6 wt.%> or any range or value there between or about 5 wt.%>. A particle size of the support material can range from 1,000 to 25,000 nm, 2,000 to 20,000 nm, 5,000 to 15,000, or any range or value there between. The particle size of the binder material can range from 50 to 100 nm, 60 to 80 nm, or any range or value there between. The metal oxide coated 3-D structured support material can be dried and/or rotated or shook to remove any excess metal oxide coating in air for a desired amount of time (1 minute to 24 hour, or 10 min to 60 min or the like). The dried metal oxide coated 3- D structured support material can be calcined to in the presence of an oxygen source (e.g., air) at 400 °C to 650 °C, 450 °C to 600 °C, or any range or value there between at a rate of 0.5 to 1.5 °C/min or 0.8 to 1 °C/min over a 2 to 6 hour, or 3 to 4 hour time period to produce a uniformly covered 3-D structured support material. Without wishing to be bound by theory, it is believed that the addition of colloidal binder particles can fill the spaces between the larger support particles, and as the solvent evaporates, result in stronger binding, and less cracks.

[0050] The coated 3-D structured support material can then be contacted with a slurry of catalytically active metal material or precursor material (e.g., M0O2). The slurry of catalytically active material can have a solids loading content of 1 wt.%> to 50 wt.%, 5 wt.%> to 45 wt.%), 10 wt.%) to 40 wt.%), or any value or range there between, or about 40 wt.%>. The slurry can be acidified using mineral acid (e.g., HNO3). The active metal/metal oxide coated 3-D structured support material can be dried and/or rotated or shook to remove any excess active metal coating in air for a desired amount of time (1 minute to 24 hour, or 10 min to 60 min or the like). The dried metal oxide coated 3-D structured support material can be calcined to in the presence of an oxygen source (e.g., air) at 400 °C to 650 °C, 450 °C to 600 °C, or any range or value there between or about 550 °C at a rate of 0.5 to 1.5 °C/min or 0.8 to 1 °C/min over a 2 to 6 hour, or 3 to 4 hour time period to produce a uniformly covered 3-D structured support material. Such a process can result in a final loading of active metal material (e.g., M0O2) of about 5 wt.% to 20 wt.%, 8 wt.%, to 13 wt.%, or 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15, 16, 17, 18 19, 20 wt.% or any value or range there between. The resulting 3-D structured monolith catalyst has a layer of active metal on a metal oxide support, which is coated on a 3- D structure monolith support material.

[0051] In another embodiment, the catalytically active material can be a component of the 3-D monolith structure. The method for preparation can include: mixing the support material with the catalytically active material in a paste; and extruding the paste through a die to form a 3-D structured monolith catalyst comprising the active material and the support material. In some instances, the paste can further include at least one binder (e.g., alumina, silica, clays, titania, zirconia, or mixtures thereof), filler, reinforcing agent, pore former, plasticizer, surfactant, lubricant, dispersant, and/or viscosity modifier (e.g., cellulose based chemicals and/or polymeric compounds such as PE, PP, PVC, PS). Water can be added to wet the paste. The obtained paste can then be molded, in particular using an extrusion press or an extruder including an extrusion die to create the monolith structure. In one aspect, a catalytically active material (e.g., ZnS or M0S2) and optional additional components can be kneaded into an extrudable paste which can be then extruded through a die to form an extruded solid (e.g., a honeycomb brick). In other aspects, the extrusion die can have various shapes (e.g., cylindrical, square, rectangular). [0052] In other embodiments, the method to prepare the 3-D structured monolith catalyst can include: obtaining a 3-D ink comprising the support material and the catalytically active material; and using the ink in a 3-D printing process to form a 3-D structured monolith catalyst comprising the active material and the support material. The ink can include an oxide support material, a catalytically active metal oxide, and a viscosity modifier. The ink can be prepared by mulling an oxide support (e.g., AI2O3 or MgAhC^) with catalytically active material (e.g., M0O3, NiO, C03O4, Fe ₂ 03 etc.) and a viscosity modifier (e.g., hydroxypropyl methylcellulose or polyacrylamide). The obtained ink can be suitable for extrusion or can be modified to increase viscosity by removing water (e.g., evaporation). Any suitable 3-D printing apparatus can be employed to prepare the 3-D structured monolith catalyst of the present invention, including for example, robotic systems similar to the A3200 system available from Aerotech Inc., USA.

[0053] Drying of the compositions and catalysts in the context of the present invention can be accomplished by various methods. Drying can include contacting the compositions and catalysts with hot air, inert gases (e.g., nitrogen, argon), or combinations thereof under static or dynamic configurations. Drying can further include other techniques such as vacuum, freeze drying (e.g., conventional or microwave), or mixtures thereof at temperature between 25 and 120 °C and all ranges and values there between (e.g., 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 1 10, or 1 15 °C) and pressures between 0.0001 MPa to 0.1 MPa and all ranges and value there between (e.g., 0.0002, 0.0005, 0.001, 0.005, 0.010, 0.05, 0.09 mbar). Drying can also be achieved for aqueous systems which can include using fully saturated water air. After drying, calcination of the 3-D structured monolith catalyst can be performed under air in a static chamber or in a dynamic furnace. The process can include heating the structure linearly to a predetermined temperature (e.g., from 400 to 1300 °C, preferably about 1 150 °C, more preferably about 500 °C) or stepwise from 25 °C to 550 °C with a heating ramp rate from 0.2 °C to 10 °C per minute, preferably 2 °C per minute, 0.8 to 1 °C per minute for a wash-coat or slip cast prepared 3-D structured monolith catalyst and 0.2 °C per minute for an extruded 3- D structured monolith catalyst. [0054] In a particular embodiment, the dry and calcined 3-D structured metal oxide or metal monolith catalyst of the present invention can be sulfurized prior to use. Sulfurization can be performed by using any sulfur containing agent. Non-limiting examples of sulfurization agents can include sulfur gas (S ₂ (g)), hydrogen sulfide (H ₂ S), carbonyl sulfide (CS ₂ ), dimethyl sulfide (DMS) or dimethyl sulfoxide (DMSO). Sulfurization can include contacting the 3-D metal oxide structured monolith catalyst with the sulfur containing agent at a temperature for a duration. In certain aspects, the sulfurization can be performed at a temperature of 150 °C to 700 °C and all values and ranges there between (e.g., 200, 250, 300, 350, 400, 450, 500, 550, 600, or 650 °C) until suitable sulfurization is achieved. In some embodiment, sulfurization is performed for a duration of 1 h to 10 h and all values and ranges there between (e.g., 2, 3, 4, 5, 6, 7, 8, or 9 h).

C. Carbon Monoxide and Sulfur Dioxide Production Process

[0055] The 3-D structured monolith catalyst of the present invention can be used as a catalyst in a variety of industrial and high temperature applications. The reaction processing conditions can be varied to achieve a desired result (e.g., carbon monoxide and sulfur dioxide product). In a preferred aspect, the process can include contacting a reaction mixture that includes gaseous C0 ₂ and gaseous elemental sulfur with any of the catalysts described throughout the specification under conditions sufficient to produce a product stream that include gaseous CO and gaseous SO2. In some aspects, the product stream can further include gaseous COS and/or gaseous CS2.

[0056] In one aspect of the invention, the catalyst of the present invention can be used in continuous flow reactors to produce gaseous CO and SO2 from gaseous CO2 and gaseous elemental S. The channels of the 3-D structured monolith catalyst traverse the catalyst from the upstream to the downstream direction on the reactant flow path. These channels can provide catalytically active wall surfaces for treating a vapor stream containing a reactant passing through the catalyst bed, at least partially converting the reactant to a product in an efficient manner and at low pressure drops. Non-limiting examples of the configuration of the catalytic material in a continuous flow reactor are provided below and throughout this specification. The continuous flow reactor can be a fixed bed reactor, a stacked bed reactor, a fluidized bed reactor, or an ebullating bed reactor. The reactors can employ radial flow, axial flow, helical flow, or mixtures thereof. Adoption of monolith structures with thin catalytic wash-coats can permit short diffusion distances with low pressure drops that can be advantageous over traditional structures where reaction selectivity is adversely affected by pore diffusion. In a preferred aspect of the invention, the 3-D structured monolith catalyst can be assembled in layers in order to fully cover the reactor's cross sectional area or mounted into a reactor having appropriate shape so the catalyst fills the reactor to avoid any preferential channeling especially in between the wall of the reactor and outer most layer of the monolith. For high efficiency, the gas mixture can be split equivalently in each channel. In other aspects, the reactor can be designed similar to conventional catalytic converter arrangements for automotive applications as described in European Patent Application Publication No. 0470653 to Yoshihiko, and U.S. Patent Nos. 4, 134,733 to Volker et al. and 5,325,665 to Kiso et al., both of which are hereby incorporated by reference. FIG. 6 depicts a system to prepare carbon monoxide (CO) and sulfur dioxide (SO2) using the 3-D honeycomb monolith catalyst in one embodiment of the present invention. The catalytic material can be arranged in the continuous flow reactor in layers {e.g., catalytic beds) or mixed with the reactant stream {e.g., ebullating bed). The combination of high surface area with low pressure drop employing the monolithic catalysts of the present invention can lead to a shorter contact time while limiting diffusion. [0057] Non-limiting processing conditions can include temperature, pressure, reactant flow, a ratio of reactants, or combinations thereof. Process conditions can be controlled to produce carbon monoxide (CO) and sulfur dioxide (SO2) with specific properties {e.g., percent CO, percent SO2, etc). The average temperature in the reactor sufficient to produce a product stream includes a reaction temperature of at least 250 °C to 3000 °C, 900 °C to 2000 °C, or 1000 °C to 1600 °C and all values and ranges there between (e.g., 1100, 1200, 1300, 1400, or 1500 °C). Pressure in the reactor sufficient to produce a product stream can include a reaction pressure of between 0.1 and 5.0 MPa and all values and ranges there between (e.g., 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, or 4.5 MPa). The gas hourly space velocity (GHSV) of the reactant feed can range from 100 h ^"1 to 100,000 h ^"1 and all values and ranges there between (e.g., 500, 1000, 5,000, 10,000, 15,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, or 90,000 h ^"1 ). In some embodiments, the GHSV can be as high as possible under the reaction conditions. The severity of the process conditions can be manipulated by changing the hydrocarbon source, the sulfur source, the reactant gas ratio, pressure, flow rates, the temperature of the process, the catalyst type, and/or catalyst to feed ratio. In one particular aspect of the present invention, the 3-D structured monolith catalyst has the ability to affect a pressure drop of less than 0.05 MPa over a bed length of 4 to 10 cm during use in a catalytic reaction.

[0058] In a non-limited embodiment, a system for producing carbon monoxide (CO) and sulfur dioxide (SO2) using the 3-D structured monolith catalyst of the present invention is described. Referring to FIG. 6, a schematic of system 600 for the production of carbon monoxide (CO) and sulfur dioxide (SO2) is depicted. System 600 may include a continuous flow reactor or an adiabatic reactor 502 and a catalytic material 604 of the present invention (shown having non-limiting honeycomb structure via cross section 606). Gaseous CO2 stream 608 and gaseous elemental stream 610 can enter the continuous flow reactor 602 via the feed inlet 612. The reactants can be provided to the continuous flow reactor at inlet 612 as separated streams or mixed together prior to entering the inlet. The reaction zone where the catalytic material 604 comes into contact with the reactant feed can be in fluid communication with the inlet or inlets. In some embodiments, the catalytic material and the reactant feed is heated to the approximately the same temperature. In some instances, catalytic material 604 can be layered in continuous flow reactor 602 or positioned in one or more tubes in an adiabatic reactor. In particular aspects, the system permits the catalytic material to be sulfurized in situ before, during, or after the reaction. The amount of gaseous elemental sulfur can be controlled to affect the rate of catalyst sulfurization/regeneration. Contact of the reactant mixture with catalytic material 604 produces gaseous product stream 614 that includes gaseous CO and gaseous SO2. Gaseous product stream 614 can exit continuous flow reactor 602 via product outlet 616. Without being limited to theory, it is believed that COS, and/or carbon disulfide CS2 can also be contained in the product stream. [0059] The process of the present invention can produce a product stream that includes a composition containing CO and SO2, and optionally COS and/or CS2. Any of the products contained in the product stream can be suitable as intermediates or as feed material in a subsequent synthesis reaction to form a chemical product or a plurality of chemical products. The product composition can be purified or mixtures of reaction products can be separated using known purification and separation methods (e.g., cryogenic distillation, membrane separation, swing adsorption techniques, etc.).

[0060] The reactants used in the systems employing the 3-D structured monolith catalysts of the present invention can include gaseous CO2 and gaseous elemental sulfur. In one non- limiting instance, the CO2 can be obtained from a waste or recycle gas stream (e.g., from a plant on the same site such as from ammonia synthesis, or a reverse water gas shift reaction) or after recovering the carbon dioxide from a gas stream. Gaseous elemental S in the context of the present invention can include all allotropes of sulfur (i.e., Sn where n = 1 to∞). Non- limiting examples of sulfur allotropes include S, S2, S ₄ , S ₆ , and Ss, with the most common allotrope being Ss. Sulfur gas can be obtained by heating solid or liquid sulfur to a boiling point of about 445° C. Alternatively, gaseous sulfur can be generated by heating elemental sulfur in a sealed container and the gaseous sulfur can then be added to the reactor or mixed with the reactant gas feed. Solid sulfur can contain either (a) sulfur rings, which may have 6, 8, 10 or 12 sulfur atoms, with the most common form being Ss, or (b) chains of sulfur atoms, referred to as catena sulfur having the formula S. Liquid sulfur is typically made up of Ss molecules and other cyclic molecules containing a range of six to twenty atoms. Solid sulfur is generally produced by extraction from the earth using the Frasch process or the Claus process. The Frasch process extracts sulfur from underground deposits. The Claus process produces sulfur through the oxidation of hydrogen sulfide (H2S). Hydrogen sulfide can be obtained from waste or recycle stream (for example, from a plant on the same site, or as a product from hydrodesulfurization of petroleum products) or recovery the hydrogen sulfide from a gas stream (for example, separation for a gas stream produced during production of petroleum oil, natural gas, or both). A benefit of using sulfur as a starting material is that it is abundant and relatively inexpensive to obtain as compared to, for example, oxygen gas. The reactant mixtures may further contain other gases, preferably other gases that do not negatively affect the reaction (e.g., reduced conversion and/or reduced selectivity). Examples of such other gases include nitrogen or argon. In some aspects of the invention, the reactant stream can be substantially devoid of other reactant gas such as oxygen gas, carbon monoxide gas, hydrogen gas, water or any combination thereof. Preferably, the reactant mixture is highly pure and substantially devoid of water. In some embodiments, the gases can be dried prior to use (e.g., pass through a drying media) or contain a minimal amount of water or no water at all. Water can be removed from the reactant gases with any suitable method known in the art (e.g., condensation, liquid/gas separation, etc.). A non-limiting commercial source of the reactants used in the current invention includes Sigma-Aldrich®, (U.S.A.), Alfa Aesar (U.S.A.), and Fischer Scientific (U.S.A.).

EXAMPLES

[0061] 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.

Example 1

(Preparation of a 3-D Structured Monolith Catalyst by Slip Casting)

[0062] The ceramic cordierite monolith material was obtained from Corning Incorporated (USA). All coating experiments were performed on pieces of cordierite monolith with height of about 1 to 2 cm and diameter of about 2.3 cm. The monoliths were received as 10-cm pieces and were cut using diamond. The channels are square shaped, with a side length of about 0.15 mm. The number of channels is approximately 145 channels per piece, some channels are lost during cutting and dipping processes.

[0063] Rotation of monolith around its axis was performed using IKA® RW 16 stirrer with an attached clamp. Mixing of slurries was performed using Hauschild SpeedMixer DAC 600.1 FVZ. Acidity was assessed using Mettler Toledo SevenGoPro pH meter. [0064] The γ-alumina, T 12 was obtained from PIDC (U.S.A., Lot G280-EXT-140301-BZ). Milling was performed using Retsch Emax and about 50 zirconia beads. Nyacol® AL20A (Nyacol® Nano technologies, Inc., U.S.A.) solution of colloidal pseudoboehmite alumina (Table 1) was used as a binder. Table 1 lists the properties of the Nyacol® AL20A. Table 2 shows a summary of the coating trials using slip casting methodology. The active phase was coated in a second step, by using 40% solid content (M0O2, Sigma-Aldrich® U.S.A.,) in in IN HNO3 (Sigma-Aldrich®). The active metal coated monolith structure was calcined in static air in a muffle furnace at 550 °C and weight difference was calculated by weighing the entire structure using micro balance. The weight loading of M0O2 was found to be approximately 8 wt.% and 12.5 wt.% for Trial 1 and Trial 2, respectively.

Table 1

Table 2

*Loading values as (Mass after calcination - Initial mass of dry monolith).

Example 2

(Characterization of Active Metal/Support/3-D-Structured Monoliths of Example 1)

[0065] FIGS. 7A-D depict scanning electron micrographs (SEM) of the Trial 1 catalytic monoliths. The broad distribution of the two ranges of particles: support particles (2-20 μπι) and binder (colloidal) particles (60-90 nm) was evident (see, circled portion in FIG. 7C). It was observed that the coating layer here was uniform with respect to cracks in the coated layer {i.e., less cracks were observed vs. pore-filling). Without wishing to be bound by theory, it is believed that although calcination temperature was thought to play a role in the formation of such cracks; as faster heating is thought to produce more cracking. However, ramp rate was not believed to be the only factor. The addition of colloidal binder particles was mainly to fill the spaces between the larger support particles as the solvent evaporates, resulting in stronger binding, and less cracks.

[0066] FIGS. 8A-8D are SEM micrographs of the Trial 2 catalytic monoliths. The coated layer had cracks overall as compared to Trial 1. Although cracking was observed, it appeared to be smaller and less frequent than in in Trial 1. However, the particles that were formed were larger than those formed in Trial 1. The larger particles range solids used in this trial are predicted to be more prone to breakage and leaving the monolith support surface than smaller ones of Trial 1 as the former are higher in mass and would have a smaller surface adhering to the monolith (with respect to their volume). Additionally, the total surface area would decreases because smaller particles have larger surface area to total volume ratio.

Prophetic Example 3

(Preparation of a 3-D Structured Monolith Catalyst by Deposition)

[0067] A monolith structure will be prepared according to Meille, V., Avila, P.;Montes, M., Mir ^' o, E.E., Monolithic reactors for environmental applications A review on preparation technologies, Chem. Eng. J. (Lausanne) 2005, 109 pp. 11-36. Separately, an aqueous slurry of catalytic active material and support material with optional additives will be prepared having a viscosity of 60 to 100 cP. The slurry will then be coated on the monolith structure by dip coating, spray coating or any other technologies with pressure or vacuum (preferably vacuum at bottom or top) using weight loading of catalytic materials to monolith from 1 : 100 to 40: 100. The resulting coated monolith will then be dried and calcined in air to afford a 3-D structured monolith catalyst. Prophetic Example 4

(Preparation of a 3-D Structured Monolith Catalyst by Kneading and Extrusion)

[0068] A prefixed catalytic active material {e.g., ZnS or M0S2) will be kneaded with components such as fillers, binders, and reinforcing agents into an extrudable paste and then extruded through a die to form a honeycomb brick. The honeycomb brick will then be dried and calcined in air to afford a 3-D structured monolith catalyst. Alternatively, a catalytic active material, refractory metal oxide support, a binder, an optional organic viscosity-enhancing compound will be mixed into a homogeneous paste and then added to a binder/matrix component or a precursor thereof and optionally one or more inorganic fibers. This blend will be then compacted in a mixing or kneading apparatus or an extruder. Organic additives such as binders, pore formers, plasticizers, surfactants, lubricants, and dispersants as processing aids can be added to the mixture as necessary to enhance wetting to produce a uniform batch. The resulting material will then be molded, in particular using an extrusion press or an extruder including an extrusion die, and dried and calcined in air to afford a 3-D structured monolith catalyst.

Prophetic Example 5

(Preparation of a 3-D Structured Monolith Catalyst by 3-D Printing)

[0069] An ink will be prepared by mulling an aqueous mixture of oxide support (AI2O3 or MgAh04) with a catalytically active metal oxide (e.g., M0O3, NiO, C03O4, Fe ₂ 03, or combinations thereof) and viscosity modifier (e.g., hydroxypropyl methylcellulose or polyacrylamide). The viscosity of the ink can be increased by removing water. The ink will then be used in a robotic system such as an A3200 system by Aerotech Inc., USA to make different kinds of monolith structures. The resulting monolith will then be dried and calcined in air to afford a 3-D structured monolith catalyst.

Prophetic Example 6

(Sulfurization of 3-D Structured Monolith Catalysts - General Procedure)

[0070] Sulfurization will be performed by exposing the 3-D structured monolith catalysts of Example 1 and prophetic Examples 3-5 to a sulfur containing compound (e.g., hydrogen sulfide (H2S), carbonyl sulfide (CS2), dimethyl sulfide (DMS) or dimethyl sulfoxide (DMSO)) at a temperature of 150 °C to 700 °C for 1 to 10 hours.

Prophetic Example 7

(Reduction of Carbon Dioxide Reaction)

[0071] The sulfurized 3-D structured monolith catalyst(s) of Example 6 will be mounted into a quartz tube so it fills the radial area. The catalyst will be heated to the desired temperature (about 1 100 °C) and then will be exposed to a gas mixture of CO2, sulfur (S ₂ ) and nitrogen with a molar composition of 4/1/10, respectively at a gas hourly space velocity (GHSV) of 4000 h ^{" l} . The unreacted sulfur will be trapped into a condenser after the reactor and the remaining effluent is analyzed by a micro gas chromatography composed of molecular sieve with a poraplot type column.