Clay mineral supported catalysts

Abstract

Disclosed is a hydrocarbon gas reforming supported catalyst, and methods for its use, that includes a catalytic material capable of catalyzing the production of a gaseous mixture comprising hydrogen (H.sub.2) and carbon monoxide (CO) from a hydrocarbon gas and a clay support material comprising a clay mineral, wherein the catalytic material is chemically bonded to the clay support material, and wherein the chemical bond is a M1-M2 bond, where M1 is a metal from the catalytic material and M2 is a metal from the clay support material, or the chemical bond is a M1-O bond, where M1 is a metal from the catalytic material and oxygen (O) is from the clay support material, wherein the supported catalyst comprises at least 70% or more by weight of the clay support material.

Claims

1. A hydrocarbon gas reforming supported catalyst comprising: (a) a catalytic material capable of catalyzing the production of a gaseous mixture comprising hydrogen (H.sub.2) and carbon monoxide (CO) from a hydrocarbon gas; and (b) a clay support material comprising a clay mineral, wherein the catalytic material is chemically bonded to the clay support material, and wherein the chemical bond is a M1-M2 bond, where M1 is a metal from the catalytic material and M2 is a metal from the clay support material, or the chemical bond is a M1-O bond, where M1 is a metal from the catalytic material and oxygen (O) is from the clay support material, wherein the supported catalyst comprises at least 70% or more by weight of the clay support material.

2. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the clay mineral comprises a 1:1 silicate layer or 2:1 silicate layer.

3. The hydrocarbon gas reforming supported catalyst of claim 2, wherein the clay mineral comprises a 1:1 silicate layer.

4. The hydrocarbon gas reforming supported catalyst of claim 3, wherein the clay mineral is a kaolin mineral.

5. The hydrocarbon gas reforming supported catalyst of claim 4, wherein the kaolin mineral is kaolinite.

6. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the supported catalyst comprises at least 80% or more by weight of the clay support material.

7. The hydrocarbon gas reforming supported catalyst of claim 6, further comprising at least 1%, or more by weight of the catalytic material.

8. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the clay support material is in particulate or powdered form.

9. The hydrocarbon gas reforming supported catalyst of claim 8, wherein the particle size of the clay support material ranges from 5 to 300 μm.

10. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the clay support material is in non-powdered form or has a fabricated geometry.

11. The hydrocarbon gas reforming supported catalyst of claim 10, wherein the fabricated geometry is a pellet, foam, honeycomb, or monolith.

12. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the catalytic material is a metal catalyst or metal oxide catalyst comprising Pt, Pd, Au, Ag, Ir, Ni, Co, Rh, Ru, La, Mg, Ca, Sr, Ba, Li, Na, K, Fe, Sn, Cu, Zn, Zr, Mo, Nb, Bi, or Mn, or any combination thereof.

13. The hydrocarbon gas reforming supported catalyst of claim 12, wherein the metal catalyst comprises Ni, Pt, Rh, or Ru or any combination thereof.

14. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the clay mineral is a purified or isolated clay mineral or a synthetic clay mineral.

15. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the supported catalyst comprises at least 1%, or more by weight of the catalytic material.

16. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the catalytic material is dispersed on the surface of the clay support material.

17. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the catalytic material comprises a pyrochlore of:
A.sub.xB.sub.y−zC.sub.zO.sub.7 wherein, A is a trivalent ion of an element of La, Ce, Nd, Bi, Sc, or Y, where 0≦x≦2, B is a tetravalent ion of an element of Zr, Pt, Pd, Ni, Mo, Rh, Ru, or Ir, where 0≦y−z≦2, C is a bivalent, trivalent or tetravalent ion of Ba, Ca, Cu, Mg, Ru, Rh, Pt, Pd, Ni, Co, or Mo, where 0≦z≦2.

18. The hydrocarbon gas reforming supported catalyst of claim 1, wherein the catalytic material comprises La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7 or La.sub.2Rh.sub.0.11Zr.sub.1.85O.sub.7 and the clay support material comprises kaolinite.

19. A method of producing the hydrocarbon gas reforming supported catalyst of claim 1 comprising obtaining a composition comprising: (a) a continuous phase comprising a solvent and a catalytic material capable of catalyzing the production of a gaseous mixture comprising hydrogen (H.sub.2) and carbon monoxide (CO) from a hydrocarbon gas, wherein the catalytic material is solubilized in the solvent; and (b) a dispersed phase comprising a clay mineral in powdered or particulate form; and evaporating the solvent from said composition, wherein the hydrocarbon gas reforming supported catalyst is produced, and wherein the catalytic material is chemically bonded to the support material, and wherein the chemical bond is a M1-M2 bond, where M1 is a metal from the catalytic material and M2 is a metal from the clay support material, or the chemical bond is a M1-O bond, where M1 is a metal from the catalytic material and oxygen (O) is from the clay support material.

20. A method of catalytically reforming a reactant gas mixture comprising: (a) providing a reactant gas mixture comprising a hydrocarbon and an oxidant; (b) providing the hydrocarbon gas reforming supported catalyst of claim 1; and (c) contacting the reactant gas mixture with the hydrocarbon gas reforming supported catalyst under conditions sufficient to produce a gaseous mixture comprising hydrogen (H.sub.2) and carbon monoxide (CO).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Illustration of 1:1 and 2:1 silicate layers present in various clay minerals.

(2) FIG. 2: Illustration of various products that can be produced from syngas.

(3) FIG. 3: Transmission electron micrograph of neat Kaolin calcined at 1000° C. for 8 hours.

(4) FIG. 4: Transmission electron micrograph of neat 10 wt % La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7/Kaolin catalyst calcined at 1000° C. for 8 hours.

(5) FIG. 5: Powder X-ray diffraction patterns of pyrochlore/kaolin catalysts (B) 20 wt % La.sub.2Ru.sub.0.11Zr.sub.1.89O.sub.7/kaolin, (C) La.sub.2Rh.sub.0.11Zr.sub.1.89O.sub.7/kaolin, (D) La.sub.2Pd.sub.0.11Zr.sub.1.89O.sub.7/kaolin and (E) La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7/kaolin.

(6) FIG. 6: Carbon dioxide reforming of methane (CDRM) with 10 wt % CeO.sub.2/2 wt % Pt/Kaolin catalysts at 800° C. and 1 bara.

(7) FIG. 7: CDRM with 10 wt % La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7/Kaolin catalysts at 800° C. and 1 bara.

(8) FIG. 8: CDRM with 10 wt % La.sub.2Pt.sub.0.11Zr.sub.1.89O.sub.7/Kaolin catalysts at 915° C. and 1 bara.

(9) FIG. 9: Performance of 20% La6.5% Ni/Kaolin catalyst: CH.sub.4 and CO.sub.2 conversion; and H.sub.2/CO ratio obtained at 800° C., 1 bara and GHSV=73,000 h.sup.−1. Gas mixture containing 45% CH.sub.4+45% CO.sub.2+10% Ar was used as feed.

(10) FIG. 10: Performance of 20% La.sub.2Rh.sub.0.11Zr.sub.1.85O.sub.7/Kaolin catalyst: CH.sub.4 and CO.sub.2 conversion; and H.sub.2/CO ratio obtained at 800° C., 1 bara and GHSV=73,000 h.sup.−1. Gas mixture containing 45% CH.sub.4+45% CO.sub.2+10% Ar was used as feed.

DETAILED DESCRIPTION OF THE INVENTION

(11) The currently available catalysts used to reform hydrocarbons into syngas are prone to coking and sintering, both of which can lead to inefficient catalyst performance and ultimately failure of the catalyst after relatively short periods of use. This can lead to inefficient syngas production as well increased costs associated with its production.

(12) A discovery has been made that avoids the coking and sintering issues described above. The discovery is based on the use of clay minerals as a support for the catalytic material. Without wishing to be bound by theory, it is believed that clay minerals such as kaolinite have increased oxygen mobility characteristics when compared with currently used support materials. In particular, certain clay minerals have chemical and structural characteristics that are believed to provide for an environment that has both high oxygen exchange capacity and mobility characteristics, thereby reducing the incidence of coking and sintering when the catalysts of the present invention are used to produce syngas.

(13) These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

(14) A. Clay Minerals

(15) There are a variety of clay minerals that can be used as support materials in the context of the present invention. Non-limiting examples of such materials are provided below. In particular aspects, however, clay minerals having a 1:1 silicate layer structural format are used (e.g., kaolinite), which are shown in the examples as having zero coking at temperatures above 800° C. when used as a support.

(16) Typically, a clay mineral includes silica, alumina or magnesia or both, and water. Some clay minerals may be expressed using ideal chemical formulas as the following: 2SiO.sub.2Al.sub.2O.sub.32H.sub.2O (kaolinite), 4SiO.sub.2Al.sub.2O.sub.3H.sub.2O (pyrophyllite), 4SiO.sub.23MgOH.sub.2O (talc), and 3SiO.sub.2Al.sub.2O.sub.3 5 FeO 4H.sub.2O (chamosite). The SiO.sub.2 ratio is a key factor for determining clay mineral types. Clay minerals can be classified on the basis of variations of chemical composition and atomic structure into nine groups: (1) kaolin-serpentine (kaolinite, halloysite, lizardite, chrysotile), (2) pyrophyllite-talc, (3) mica (illite, glauconite, celadonite), (4) vermiculite, (5) smectite (montmorillonite, nontronite, saponite), (6) chlorite (sudoite, clinochlore, chamosite), (7) sepiolite-palygorskite, (8) interstratified clay minerals (e.g., rectorite, corrensite, tosudite), and (9) allophane-imogolite.

(17) The prevalent structural feature of clay minerals is the presence of hydrous-layer silicates. These features are continuous two-dimensional tetrahedral sheets of Si.sub.2O.sub.5, with SiO.sub.4 tetrahedrons linked by the sharing of three corners of each tetrahedron to form a hexagonal mesh pattern. The apical oxygen at the fourth corner of the tetrahedrons, which is usually directed normal to the sheet, forms part of an adjacent octahedral sheet in which octahedrons are linked by sharing edges. There are two major types for the structural “backbones” of clay minerals called silicate layers. The unit silicate layer formed by aligning one octahedral sheet to one tetrahedral sheet is referred to as a 1:1 silicate layer, and the exposed surface of the octahedral sheet consists of hydroxyls. In another type, the unit silicate layer consists of one octahedral sheet sandwiched by two tetrahedral sheets that are oriented in opposite directions and is termed a 2:1 silicate layer. Therefore, a clay mineral comprising a 1:1 silicate layer is one in which an octahedral sheep is aligned with a tetrahedral sheet. By comparison, a clay mineral comprising a 2:1 silicate layer is one in which an octahedral sheet is aligned with a tetrahedral sheet on one side and a second tetrahedral sheet on the opposing side. FIG. 1 provides an illustration of 1:1 and 2:1 silicate layers.

(18) Kaolin-serpentine groups of clay minerals are 1:1 layer silicates. Their basic unit of structure includes tetrahedral and octahedral sheets in which the anions at the exposed surface of the octahedral sheet are hydroxyls. Therefore, their general structure can be expressed as: Y.sub.2-3Z.sub.2O.sub.5(OH).sub.4, where Y are cations in the octahedral sheet such as Al.sup.3+ and Fe.sup.3+ for dioctahedral species and Mg.sup.2+, Fe.sup.2+, Mn.sup.2+, and Ni.sup.2+ for trioctahedral species, and Z are cations in the tetrahedral sheet, largely Si and, to a lesser extent, Al and Fe.sup.3+. Kaolinite has a structural formula of Al.sub.2Si.sub.2O.sub.5(OH).sub.4. Kaolinite is electrostatically neutral and has triclinic symmetry. Dickite and nacrite are polytypic varieties of kaolinite, both of which include a double 1:1 layer and have monoclinic symmetry, but have different stacking sequences of the two 1:1 silicate layers. Halloysite also has a composition close to that of kaolinite and is characterized by its tubular nature in contrast to the platy nature of kaolinite particles. Halloysite has a hydrated form with a composition of Al.sub.2Si.sub.2O.sub.5(OH).sub.4 2H.sub.2O. This hydrated form irreversibly changes to a dehydrated variety at relatively low temperatures (60° C.) or upon being exposed to conditions of low relative humidity. Trioctahedral magnesium species, chrysotile, antigorite, and lizardite, have a formula of Mg.sub.3Si.sub.2O.sub.5(OH).sub.4. Chrysotile crystals have a cylindrical roll morphology. Antigorite crystals exhibit an alternating wave structure. Lizardite crystals are platy and can include a small amount of substitution of aluminum or ferric iron for both silicon and magnesium.

(19) With respect to the pyrophyllite-talc group of clay minerals, they have a 2:1 layer form with a unit thickness of approximately 9.2 to 9.6 Å. The structure is an octahedral sheet sandwiched by two tetrahedral sheets. Pyrophyllite and talc represent the dioctahedral and trioctahedral members, respectively, of the group. The structural formulas are Al.sub.2Si.sub.4O.sub.10(OH).sub.2 for pyrophyllite and Mg.sub.3Si.sub.4O.sub.10(OH).sub.2 for talc. Therefore, the 2:1 layers of these minerals are electrostatically neutral and are held together with van der Waals bonding.

(20) Mica clay minerals also have a basic structural unit of the 2:1 layer type like pyrophyllite and talc. Examples include muscovite (KAl.sub.2(Si.sub.3Al)O.sub.10(OH).sub.2), phlogopite (KMg.sub.3(Si.sub.3Al)O.sub.10(OH).sub.2), biotite (K(Mg, Fe).sub.3(Si.sub.3Al)O.sub.10(OH).sub.2), celadonite (K(Mg, Fe.sub.3+)(Si.sub.4−xAl.sub.x)O.sub.10(OH).sub.2, where x=0-0.2), and Glauconite.

(21) The vermiculite clay mineral includes sheets of trioctahedral mica or talc separated by layers of water molecules.

(22) Smectite clay minerals are derived from the structures of pyrophyllite and talc. Unlike pyrophyllite and talc, the 2:1 silicate layers of smectite have a slight negative charge due to ionic substitutions in the octahedral and tetrahedral sheets. The structural formula of smectites include (Al.sub.2−yMg.sup.2+/.sub.y)(Si.sub.4−xAl.sub.x)O.sub.10(OH).sub.2M.sup.+/.sub.x+y nH.sub.2O, where M.sup.+ is the interlayer exchangeable cation expressed as a monovalent cation and where x and y are the amounts of tetrahedral and octahedral substitutions, respectively (0.2≦x+y≦0.6). The smectites with y>x are called montmorillonite and those with x>y are known as beidellite. Nontronites are those in which ferric iron is a dominant cation in the octahedral sheet instead of aluminum and magnesium. Beidellites are those where chromium (Cr.sup.3+) and vanadium (V.sup.3+) also are found as dominant cations in the octahedral sheets. Trioctahedral ferromagnesian smectites have the following formula (Mg, Fe.sup.2+).sub.3(Si.sub.4−xAl.sub.x)O.sub.10(OH).sub.2M.sup.+/x nH.sub.2O.

(23) Chlorite clay minerals include: clinochlore (Mg.sub.5Al)(Si.sub.3Al)O.sub.10(OH).sub.8; chamosite (Fe.sub.5.sup.2+Al)(Si.sub.3Al)O.sub.10(OH).sub.8; pennantite (Mn.sub.5Al)(Si.sub.3Al)O.sub.10(OH).sub.8; and (nimite) (Ni.sub.5Al)(Si.sub.3Al)O.sub.10(OH).sub.8.

(24) Sepiolite and palygorskite are papyrus-like or fibrous hydrated magnesium silicate minerals. They include two-dimensional tetrahedral sheet of composition Si.sub.2O.sub.5 and are regarded as having narrow strips or ribbons of 2:1 layers that are linked stepwise at the corners. The structure of sepiolite is Mg.sub.8Si.sub.12O.sub.30(OH).sub.4(OH.sub.2).sub.4(H.sub.2O).sub.8, and the structure of palygorskite is and (Mg, Al).sub.5Si.sub.8O.sub.20(OH).sub.2(OH.sub.2).sub.4(H.sub.2O).sub.4.

(25) Interstratified clay minerals include mixtures of various clay minerals. Examples include rectorite (dioctahedral mica/montmorillonite), tosudite (dioctahedral chlorite/smectite), corrensite (trioctahedral vermiculite/chlorite), hydrobiotite (trioctahedral mica/vermiculite), aliettite (talc/saponite), and kulkeite (talc/chlorite). Other examples include illite/smectite, glauconite/smectite, dioctahedral mica/chlorite, dioctahedral mica/vermiculite, and kaolinite/smectite.

(26) Imogolite clay mineral is an aluminosilicate with an approximate composition of SiO.sub.2Al.sub.2O.sub.3 2.5H.sub.2O. Allophane is a hydrous aluminosilicate mineral dominated by Si—O—Al bonds—i.e., the majority of aluminum atoms are tetrahedrally coordinated. Unlike imogolite, the morphology of allophane varies from fine, rounded particles through ring-shaped particles to irregular aggregates.

(27) Any of the above noted clay minerals can be used in the context of the present invention. Further, while it is contemplated that natural/non-purified or non-isolated or non-synthetic forms can be used, in certain aspects, the clay minerals can be isolated or purified or synthetically produced. One of the reasons for using isolated or purified or synthetically produced clay minerals is to reduce or remove impurities that may cause or lead to sintering of the minerals or coking on the surface of the minerals when used as a support for a catalyst in reforming reactions. Such impurities that may induce sintering or coking during syngas production include iron, nickel, manganese, sodium, potassium, chloride, calcium, lithium, rubidium, berylium, barium, SiO.sub.2, and/or organic impurities. By way of example, when clay minerals are heated at elevated temperatures such as those used in carbon dioxide reformation of hydrocarbons to produce syngas, such impurities (e.g., iron or potassium) within the clay mineral could fuse together. Removal or reducing the amounts of such impurities can therefore help reduce or avoid sintering and/or coking.

(28) B. Catalytic Materials

(29) It is contemplated that any of the known catalytic materials that are currently used in producing syngas from hydrocarbons can be used in the context of the present invention. Such catalytic materials can be supported by the clay minerals discussed above and throughout this specification, thereby resulting in a hydrocarbon gas reforming clay mineral supported catalyst of the present invention. Non-limiting examples of such catalysts can include metal catalysts (e.g., Pt, Pd, Au, Ag, Ir, Ni, Co, Rh, Ru, La, Mg, Ca, Sr, Ba, Li, Na, K, Fe, Sn, Cu, Zn, Zr, Mo, Nb, Bi, or Mn, or any combination thereof), metal oxide catalysts (e.g., La.sub.2O.sub.3, Ru.sub.2O.sub.3, CeO.sub.2, ZrO.sub.2, ZnO, MoO.sub.3, WO.sub.3, Nb.sub.2O.sub.5, and/or Ta.sub.2O), pyrochlore catalysts, and other known catalysts used in the production of syngas from hydrocarbons (e.g., perovskites type solid solutions, various metals like Pt, Pd, Ir, Ni, Co, Rh, Ru, La, Mg, Ca, Sr, Ba, Fe, Sn, Cu, or Zn supported on various metal oxides such as Al.sub.2O.sub.3, SiO.sub.2, SBA-15, MCM-40, TiO.sub.2, ZrO.sub.2, CeO.sub.2, etc.). Non-limiting examples of pyrochlore catalysts include those having the following structure:
A.sub.xB.sub.y−zC.sub.zO.sub.7
wherein, A is a trivalent ion of an element of La, Ce, Nd, Bi, Sc, or Y, where 0<x<2, B is a tetravalent ion of an element of Zr, Pt, Pd, Ni, Mo, Rh, Ru, or Ir, where 0<y−z<2, C is a bivalent, trivalent or tetravalent ion of Ba, Ca, Cu, Mg, Ru, Rh, Pt, Pd, Ni, Co, or Mo, where 0<z<2.
C. Methods of Making and Using the Clay Mineral Supported Catalysts

(30) The clay mineral supported catalysts of the present invention can be made by processes known in the art that provide attachment of the catalytic material to the surface of the clay mineral. The attachment can be through chemical bonds or physical bonds or both. In particular instances, the bonds can be M1-M2 bonds (where M1 is a metal from the catalyst and M2 is a metal from the clay mineral) or M1-O bonds (where M1 is a metal from the catalyst and O is oxygen from the clay mineral).

(31) In addition to known methods, it has been discovered that the following process could be used to prepare the clay mineral supported catalysts of the present invention:

(32) 1. Preparation of a dispersion: (a) obtain a solution that includes a solvent (e.g., any solvent that can solubilize the catalytic material—non-limiting examples include water, methanol, ethanol, propanol, isopropanol, butanol, or mixtures thereof) and a catalytic material dissolved in said solvent. (b) obtain a clay mineral, such as one described above. It can be in particulate or powdered form. (c) mix the clay mineral with the solvent to create a dispersion, where the continuous phase includes the solution and the discontinuous/dispersed phase includes the clay mineral. Mixing can occur for a period of time to create the dispersion and to contact the clay mineral with the catalytic material. In one non-limiting aspect, the mixing time can occur for 5, 10, 15, 20, 25, 30, 40, 50, 60, or more minutes. In particular instances, the mixing can occur for about 10 to about 20 minutes or about 15 minutes. Any type of mixing apparatus can be used. (d) optionally, additional materials or ingredients or other clay minerals can be added to stabilize the dispersion, modify the resulting catalyst or clay mineral, etc. For instance, a chelating agent (e.g., citric acid, EDTA, disodium EDTA, trisodium EDTA, EGTA, phosphoric acid, succinic acid, etc.) can be added to keep the metal ions apart during the initial stages of synthesis, which leads to the formation of smaller particles in catalysts. Smaller particles can result in higher surface area and pore volume which can have a positive effect on the activity of the catalysts of the present invention.

(33) 2. Processing of the dispersion to create a catalyst: (a) subject the dispersion to a drying step such that the solvent is removed. An evaporation apparatus such as a rotary evaporator can be used. The resulting sample is dried and in powdered or particulate form. (b) the sample from (a) can then be subjected to a calcination step. Such a step can include placing the sample in a ceramic crucible and subjecting it to heat (e.g., from a muffle furnace). The sample can first be subjected to a temperature of 150° C. for 2 hours followed by 900° C. for 8 hours, with the temperature increasing at a rate of 10° C./min.

(34) The obtained material can then be used as a catalyst to produce syngas. As confirmed in the Examples section, no coking or sintering is observed when the catalyst is used at temperatures of at least 800° C., whereas coking is observed at temperatures of 700° C. Therefore, the reaction temperature for syngas production using the catalysts of the present invention can be a range of greater than 700° C. to 1100° C. or a range from 725° C., 750° C., 775° C., or 800° C. to 900° C., 1000° C., or 1100° C. In particular instances, the range can be from 800° C. to 1000° C. or from 800° C. to 1100° C. In addition to temperature, a pressure range from 1 bara to 30 bara, and/or at a gas hourly space velocity (GHSV) range from 500 to 10000 h.sup.−1 can be used as the reaction conditions for producing syngas from a hydrocarbon material and the catalysts of the present invention.

(35) A benefit of this process of making and using the catalyst is its simplicity and ease of scalability for industrial/large scale applications.

(36) The carbon dioxide in the gaseous feed mixture used in the process of the invention can be obtained from various sources. In one non-limiting instance, the carbon dioxide can be obtained from a waste or recycle gas stream (e.g. from a plant on the same site, like for example from ammonia synthesis) or after recovering the carbon dioxide from a gas stream. A benefit of recycling such carbon dioxide as starting material in the process of the invention is that it can reduce the amount of carbon dioxide emitted to the atmosphere (e.g., from a chemical production site). The hydrogen in the feed may also originate from various sources, including streams coming from other chemical processes, like ethane cracking, methanol synthesis, or conversion of methane to aromatics. The gaseous feed mixture comprising carbon dioxide and hydrogen used in the process of the invention may further contain other gases, provided that these do not negatively affect the reaction. Examples of such other gases include steam or oxygen. The hydrocarbon material used in the reaction can be methane.

(37) The resulting syngas can then be used in additional downstream reaction schemes to create additional products. FIG. 2 is an illustration of various products that can be produced from syngas. Such examples include chemical products such as methanol production, olefin synthesis (e.g., via Fischer-Tropsch reaction), aromatics production, carbonylation of methanol, carbonylation of olefins, the reduction of iron oxide in steel production, etc.

EXAMPLES

(38) 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

Synthesis of Clay Supported Catalysts

(39) The following procedure was used to synthesize 10 wt % and 20 wt % of La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7 pyrochlore catalysts grafted on Kaolin support: 0.8 g of La(NO.sub.3).sub.3.6H.sub.2O, 0.4 g of ZrCl.sub.4, 0.02 g of NiCl.sub.2.6H.sub.2O was dissolved in 7.5 ml of de-ionized water to form a clear solution. 0.4 g of citric acid was added to the above solution. To this 5.1 g of purified kaolin powder (linear formula Al.sub.2Si.sub.2O.sub.5(OH).sub.4) (obtained from Sigma-Aldrich®—K7375) was added and transferred the flask to the Rota evaporator. The material was allowed to mix in the Rota evaporator for 15 minutes and then evaporated the solvent under vacuum until the sample got dried completely. FIG. 3 is a transmission electron micrograph of neat Kaolin calcined at 1000° C. for 8 hours. FIG. 4 is a transmission electron micrograph of neat 10 wt % La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7/Kaolin catalyst calcined at 1000° C. for eight hours. For the 20 wt % catalyst, the quantities of metal precursors were doubled. It is contemplated that various wt % can be used in the context of the present invention, such as about 5%, 10%, 15%, 20%, 25%, 50% or more. Further, the kaolin powder can be substituted for another clay mineral, and the pyrochlore catalysts can be varied by varying the starting materials. Using this procedure, the following additional kaolin supported pyrochlore catalysts were also prepared: 10 wt % La.sub.2Pt.sub.0.11Zr.sub.1.89O.sub.7/kaolin; 20 wt % La.sub.2Ru.sub.0.11Zr.sub.1.89O.sub.7/kaolin; 20 wt % La.sub.2Rh.sub.0.11Zr.sub.1.89O.sub.7/kaolin; and 20 wt % La.sub.2Pd.sub.0.11Zr.sub.1.89O.sub.7/kaolin. FIG. 5 includes powder X-ray diffraction patterns of pyrochlore/kaolin catalysts (B) 20 wt % La.sub.2Ru.sub.0.11Zr.sub.1.89O.sub.7/kaolin, (C) 20 wt % La.sub.2Rh.sub.0.11Zr.sub.1.89O.sub.7/kaolin, (D) 20 wt % La.sub.2Pd.sub.0.11Zr.sub.1.89O.sub.7/kaolin and (E) 20 wt % La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7/kaolin.

(40) The following two-step procedure was used to synthesize a 10 wt % CeO.sub.2/2 wt % Pt catalyst grafted on Kaolin support. In the first step 0.17 g of tetrammine platinum chloride hydrate salt was dissolved in pore volume equivalent of water and impregnated with dried 4.9 g of Kaolin. The resultant product was first dried at 125° C. for 2 h followed by calcination at 200° C. for 4 h. In a second step, a required amount of 0.5 g of cerium ammonium nitrate salt was dissolved in pore volume equivalent of water and impregnated with Pt/Kaolin sample. The resultant mixture was first dried at 150° C. for 2 h followed by calcination at 900° C. for 8 h. Different weight percentages and catalysts can be obtained by adjusting the amount of and types of ingredients as desired.

(41) The following procedure was used to synthesize a La, Ni catalyst grafted on Kaolin support: 2.95 g of La(NO.sub.3).sub.3.6H.sub.2O and 1.62 g of NiCl.sub.2.6H.sub.2O was dissolved in 7.5 ml of de-ionized water to form a clear solution. 1.57 g of citric acid was added to the above solution. To this 4.52 g of Kaolin powder was added and transferred the flask to the Rota evaporator. The material was allowed to mix in the Rota evaporator for 15 minutes and then evaporated the solvent under vacuum until the sample got dried completely.

(42) Table 1 provides a summary of some of the produced kaolin supported catalysts:

(43) TABLE-US-00001 TABLE 1 Kaolin Supported Catalyst Solvent Used Surface Area (m.sup.2/g) 10% La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7 water 16.3 20% La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7 water 8.8 10% La.sub.2Pt.sub.0.11Zr.sub.1.89O.sub.7 water 18.2 10% CeO.sub.2/2 wt % Pt/Kaolin water 15.0 La,Ni/Kaolin water 14.8

Example 2

Use of Clay Supported Catalysts

(44) CDRM reactions with 10 wt % CeO.sub.2/2 wt % Pt/Kaolin, 10 wt % La.sub.2Ni.sub.0.11Zr.sub.1.89O.sub.7/Kaolin and 10 wt % La.sub.2Pt.sub.0.11Zr.sub.1.89O.sub.7/Kaolin were performed at 800° C. and 1 bara, 800° C. and 1 bara, and 915° C. and 1 bara, respectively, for 20 hours. Prior to the reactions, each of the catalysts were first reduced in 10% H.sub.2 atmosphere at 900° C. for 4 h. Subsequently, the CDRM reactions were each initiated by changing the gas mixture to 10% CH.sub.4+10% CO.sub.2+80% N.sub.2. Both GC and Mass spectrometer were used to monitor gas composition. The 200-500 mesh size catalyst powder was used for testing, and the GHSV applied was 5000 h.sup.−1. Comparative CDRM reactions for each of the catalysts were also performed at the same pressure (1 bara) but at a temperature of 700° C. and coking and catalyst deactivation occurred at this temperature.

(45) The CO/H.sub.2 ratio obtained from the reactions was about 1:1 (see FIGS. 6-8). Further, each of the catalysts were found to be stable without any deactivation for 20 h of duration. Notably, coke formation was not observed (no appearance of dark black color on catalysts) in any of these catalysts at temperatures above 800° C. This was confirmed by performing a loss on ignition test of the used catalysts in an open atmosphere at 800° C. By comparison, coke formation was observed (catalyst turned dark black in color) at a temperature of 700° C. Further, no sintering was observed.

(46) Therefore, a critical reaction temperature range to prevent coke formation for the catalysis of the present invention has been discovered.

Example 3

Additional Catalysts

(47) Two additional clay supported catalysts, 20% La6.5% Ni/Kaolin and 20% La.sub.2Rh.sub.0.11Zr.sub.1.85O.sub.7/Kaolin, were tested for CO.sub.2 reforming of methane at 800° C. and 1 bara pressure. Both catalysts showed very good activity over a period of 180 and 100 hours respectively (see FIG. 9 (20% La6.5% Ni/Kaolin) and FIG. 10 (20% La.sub.2Rh.sub.0.11Zr.sub.1.85O.sub.7/Kaolin)). Both catalysts were prepared according to the procedures used in Example 1.

(48) The performance of both of these catalysts were tested in a highthroughput reactor system supplied by HTE, Germany. Reactors were of plug flow type and made up of steel SS316, with an inner ceramic liner. Ceramic liner with 5 mm in diameter and 55 cm in length was used to avoid coking due to methane cracking on steel surface. The gas between the inner steel surface and outer ceramic liner wall was sealed with the help of leak proof graphite ferrule, which ensures 100% feed gas passes through ceramic liner containing catalyst and inert material. Catalyst pellets were crushed and sieved between 100-300 μm. A required amount of catalyst sieve fraction was placed on top of inert material inside the ceramic liner. A mixture of (45% CO.sub.2+45% CH.sub.4+10% Ar) was used as feed. Argon was used as an internal standard for GC analysis. Each catalyst in oxidized state was heated to 800° C. in the presence of (90% N.sub.2+10% Ar). The (CH.sub.4+CO.sub.2) mixture was dosed in 4 steps with 5 minutes intervals replacing equivalent amount of nitrogen in each step. All catalysts were tested at 800° C., 1 bar pressure and approximately gas hourly space velocity (GHSV)=25,000 h-1. After reaching feed composition of (45% CO.sub.2+45% CH.sub.4+10% Ar), gas analysis was started after 1 hour of equilibration time. Agillent GC 7867 was used for gas analysis. Methane and CO.sub.2 conversion was calculated as follows,

(49) $\mathrm{Methane}\mathrm{conversion}=\frac{\mathrm{mol}\mathrm{of}\mathrm{methane}\mathrm{converted}}{\mathrm{mol}\mathrm{of}\mathrm{methane}\mathrm{in}\mathrm{feed}}\times 100$$\mathrm{Carbon}\mathrm{dioxide}\mathrm{conversion}=\frac{\mathrm{mol}\mathrm{of}\mathrm{carbon}\mathrm{dioxide}\mathrm{converted}}{\mathrm{mol}\mathrm{of}\mathrm{carbon}\mathrm{dioxide}\mathrm{in}\mathrm{feed}}\times 100$

(50) The ratio of hydrogen to carbon monoxide is calculated as follows,

(51) $H2\text{/}\mathrm{CO}=\frac{\mathrm{mol}\mathrm{of}\mathrm{Hydrogen}\mathrm{in}\mathrm{product}}{\mathrm{mol}\mathrm{of}\mathrm{carbon}\mathrm{monoxide}\mathrm{in}\mathrm{product}}.$

(52) In the case of (20% La6.5% Ni/Kaolin) and (20% La.sub.2Rh.sub.0.11Zr.sub.1.85O.sub.7/Kaolin), the H.sub.2/CO ratio obtained was ≈0.75 (See FIGS. 9 and 10). This is because of reverse water gas shift reaction (CO.sub.2+H.sub.2=CO+H.sub.2O). The reverse water gas shift reaction is dependent on methane and CO.sub.2 conversion, at higher conversion shift reaction reaches equilibrium giving higher H.sub.2/CO ratio. So, H.sub.2/CO ratio is not catalyst specific. The H.sub.2/CO ratio near to 1 can be obtained by increasing the CH.sub.4 and CO.sub.2 conversion by decreasing the GHSV, h.sup.−1 of the catalytic reaction.