Nanocatalysts, preparation methods and applications for reforming carbon dioxide and methane to syngas

Abstract

The catalyst in this present application includes a support and an active component dispersed on/in the support; wherein the support is at least one selected from inorganic oxides and the support contains macropores and mesopores; and the active component includes an active element, and the active element contains an iron group element. As a high temperature stable catalyst for methane reforming with carbon dioxide, the catalyst can be used to produce syngas, realizing the emission reduction and recycling utilization of carbon dioxide. Under atmospheric pressure and at 800° C., the supported metal catalyst with hierarchical pores shows excellent catalytic performance. In addition to high activity and good selectivity, the catalyst has high stability, high resistance to sintering and carbon deposition.

Claims

1. A catalyst, which includes a support, a modification component and an active component dispersed on/in the support; wherein the support is at least one selected from inorganic oxides and the support contains macropores and mesopores; wherein the active element is composed of platinum and cobalt, and the modification element is composed of erbium and potassium; wherein the molar ratio of platinum, cobalt, erbium and potassium is: Pt:Co:Er:K=0.1%˜5%:1%˜10%:0.3%˜5%:0.2%˜5%; the average pore size of the macropores is greater than 50 nm, and the average pore size of the mesopores is in a range from 1 nm to 50 nm; and the particle size of the active component dispersed on/in the support is in a range from 1 nm to 50 nm.

2. The catalyst according to claim 1, wherein the average pore size of the macropores is in a range from 1 μm to 2 μm; the average pore size of the mesopores is in a range from 5 nm to 15 nm; and the specific surface area of the support is in a range from 100 m.sup.2/g to 350 m.sup.2/g.

3. The catalyst according to claim 1, wherein the weight percentage content of cobalt belonging to the active element in the catalyst is in a range from 1% to 10%; and the weight percentage content of platinum belonging to the active element in the catalyst is in a range from 0.1% to 5%.

4. The catalyst according to claim 1, wherein particle size of the active component dispersed on/in the support is in a range from 1 nm to 15 nm; and particle size of the modification component dispersed on/in the support is in a range from 1 nm to 50 nm.

5. The catalyst according to claim 1, wherein the weight percentage content of cobalt belonging to the active element in the catalyst is in a range from 3% to 6%; and the weight percentage content of platinum belonging to the active element in the catalyst is in a range from 0.5% to 3%.

6. The catalyst according to claim 1, wherein the weight percentage content of potassium in the catalyst is in a range from 0.1% to 10%.

7. A method for preparing the catalyst according to claim 1, which includes at least the steps as follows: a) impregnating the support in a solution containing the active element and the modified element, wherein the active element is composed of platinum and cobalt, and the modification element is composed of erbium and potassium, wherein the molar ratio of platinum, cobalt, erbium and potassium is: Pt: Co: Er: K=0.1%˜5%: 1%˜10%: 0.3%˜5%: 0.2%˜5%; b) separating to obtain the impregnated solid obtained in step a) which is dried, calcined under an air atmosphere and reduced by hydrogen to obtain the catalyst.

8. The method according to claim 7, wherein in step a), the impregnation is an ultrasound impregnation; and the total immersion time is in a range from 24 hours to 96 hours, and accumulation of the ultrasonic time is in a range from 2 hours to 10 hours; and in step b), the drying is conducted at a temperature range from 60° C. to 200° C.

9. The method according to claim 7, wherein in step b), the drying is vacuum drying conducted under a temperature range from 60° C. to 100° C. for a time range from 8 hours to 10 hours.

10. The method according to claim 7, wherein in step a), the ultrasound impregnation is an intermittent ultrasound impregnation; and the total immersion time is in a range from 36 hours to 60 hours, and accumulation of the ultrasonic time is in a range from 2 hours to 6 hours.

11. The method according to claim 7, wherein in step b), the temperature is raised from room temperature to a calcination temperature at a heating rate range from 1° C./min to 10° C./min to calcine the impregnated solid for no less than 1 hour, and the calcination temperature is in a range from 300° C. to 800° C.

12. The method according to claim 7, wherein in step b), the temperature is raised from room temperature to a calcination temperature at a heating rate range from 1° C./min to 5° C./min to calcine the impregnated solid for a time range from 2 hours to 4 hours, and the calcination temperature is in a range from 500° C. to 700° C.

13. The method according to claim 7, wherein in step b), the reduction by hydrogen is that the temperature is raised from room temperature to a reduction temperature at a heating rate range from 5° C./min to 20° C./min to reduce in hydrogen or a mixture of hydrogen and an inactive gas for no less than 1 hour, and the reduction temperature is in a range from 600° C. to 1000° C.; and flow velocity of hydrogen or the mixture of hydrogen and the inactive gas is in a range from 20 mL/min to 80 mL/min.

14. The method according to claim 7, wherein in step b), the reduction by hydrogen is that the temperature is raised from room temperature to a reduction temperature at a heating rate range from 5° C./min to 15° C./min to reduce in hydrogen for a time range from 1 hour to 2 hours, and the reduction temperature is in a range from 800° C. to 1000° C.; and the flow velocity of hydrogen is in a range from 20 mL/min to 40 mL/min.

15. The catalyst according to claim 1, wherein the weight percentage content of potassium in the catalyst is in a range from 0.1% to 5%.

16. A method of producing syngas by reforming methane with carbon dioxide comprises contacting the reactant containing methane and carbon dioxide with the catalyst of claim 1 to produce syngas at a reaction temperature from 600° C. to 900° C. and a reaction pressure from 0.1 MPa to 0.5 MPa; and in the reactant, the molar ratio of carbon dioxide to methane is as follows: carbon dioxide: methane is in a range from 0.5 to 2.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 are SEM images of the section of hierarchical pored aluminium oxide microsphere I; (a) is a 1100 times magnified SEM image; (b) is a 35000 times magnified SEM image.

(2) FIG. 2 are chromatography test results of the product of the reforming methane reaction with carbon dioxide in which sample CAT-I-1 was used; (a) is the testing result from thermal conductivity detector (TCD); (b) is the testing result from flame ionization detector (FID).

(3) FIG. 3 is the testing result of catalytic stability of sample CAT-I-1.

(4) FIG. 4 are transmission electron microscope images of CAT-I-1 tested before and after the reaction; (a) is the transmission electron microscopy image of CAT-I-1 tested before the reaction; (b) is the transmission electron microscopy image of CAT-I-1 tested after reacting for 102 hours at 800° C.

(5) FIG. 5 are figures comparing the catalytic activity between samples CAT-II-1 and DCAT-II-1; (a) shows the conversion rate of carbon dioxide; (b) shows the conversion rate of methane.

(6) FIG. 6 are chromatography test results of the product of the reforming methane reaction with carbon dioxide in which sample CAT-II-1 was used; (a) is the testing result from thermal conductivity detector (TCD); (b) is the testing result from flame ionization detector (FID).

(7) FIG. 7 is the testing result of catalytic stability of sample CAT-II-1.

(8) FIG. 8 are transmission electron microscope images of CAT-II-1 tested before and after the reaction; (a) is the transmission electron microscopy image of CAT-II-1 tested before the reaction; (b) is the transmission electron microscopy image of CAT-II-1 tested after reacting for 102 hours at 800° C.

(9) FIG. 9 are figures comparing the catalytic stability of samples CAT-III-1, CAT-III-2 and CAT-III-17; wherein, (a) shows the relationship of conversion rate of carbon dioxide and the reaction time; (b) shows the relationship of conversion rate of methane and the reaction time.

(10) FIG. 10 are transmission electron microscope images of sample CAT-III-1, sample CAT-III-17 and CAT-III-18; (a) is the transmission electron microscopy image of sample CAT-III-1, (b) is the transmission electron microscopy of sample CAT-III-17, (c) is the transmission electron microscopy image of sample CAT-III-18.

DETAILED DESCRIPTION OF THE EMBODIMENT

(11) The present invention will be further illustrated in combination with the following examples, but the present invention is not limited to these examples. Meanwhile, though the examples provide some conditions for producing catalysts, it does not mean that all these conditions must be fully met to achieve the goal.

(12) If there is no special notification, raw materials used in the examples are purchased commercially and the devices are used with parameter settings recommended by the producer.

(13) In the examples, SEM images of the samples are obtained using HITACHI S4800 scanning electron microscope; the transmission electron microscope images of the samples are obtained using FEI Company's F20 transmission electron microscope.

(14) In the examples, the ultrasonic apparatus used for ultrasonic immersing is KQ300ED ultrasonic apparatus produced by Kunshan ultrasonic apparatus corporation limited.

(15) In the examples, the loading quantities of iron group elements, noble metal elements, alkali metal elements, alkaline earth elements and rare earth elements are determined by plasma emission spectroscopy (ICP) on Ultima 2 apparatus produced by HORIBA JY Corporation in France.

(16) In the examples, the detection of the product generated in the reaction of preparing syngas from reforming methane with carbon dioxide is carried out on SHIMAZU GC-2014 chromatograph (TDX-01 column).

(17) In the examples, the specific surface area of the hierarchical aluminum oxide microsphere I is 197.91 m.sup.2/g, the average pore size of the macropores is 1.52 and the average pore size of the mesopores is 9.80 nm; the specific surface area of the hierarchical aluminum oxide microsphere II is 200.45 m.sup.2/g, the average pore size of the macropores is 1.61 μm, and the average pore size of the mesopores is 10.23 nm; the specific surface area of the hierarchical aluminum oxide microsphere III is 213.09 m.sup.2/g, the average pore size of the macropores is 1.57 μm, and the average pore size of the mesopores is 11.08 nm.

Example 1 Preparation and Characterization of the Catalyst

(18) Certain amounts of active component metal salts and/or modification component were dissolved in 10 mL of water to form an aqueous solution, and then 5 g of support was added for ultrasonic impregnation, and then solvent and surplus metal salts that had not been absorbed were filtered out. Support which absorbed the metal ion was dried under vacuum at 80° C. for 8 h, calcined under air atmosphere and reduced by hydrogen to obtain the catalyst.

(19) Relationships between the number of the samples and specific experiment conditions, supports, raw materials are shown in Table 1.

(20) TABLE-US-00001 TABLE 1 Metal Range of salts and Time of Percentage particle the ultrasonic Calcination Hydrogen-Reduction composition size Sample Support dosage impregnation Condition Condition of metals (nm) CAT-I-1 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 4.5% 10-45 pored acetate for 48 h; 600° C.for 4 h; reduction at aluminium (5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 4 h 10° C. /min; I flow rate: 30 mL/min CAT-I-2 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 3.55% 10-40 pored acetate for 48 h; 600° C. 4 h; reduction at aluminium (2.5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 4 h 10° C. /min; I flow rate: 30 mL/min CAT-I-3 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 5% 10-50 pored acetate for 48 h; 600° C.for 4 h; reduction at aluminium (7.5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 4 h 10° C. /min; I flow rate: 30 mL/min CAT-I-4 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-45 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.4% aluminium (5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 4 h 10° C. /min; I flow rate: 30 mL/min CAT-I-5 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-40 pored acetate for 24 h; 600° C. for 4 h; reduction at 4.3% aluminium (5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 10 h 10° C. /min; I flow rate: 30 mL/min CAT-I-6 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-50 pored acetate for 96 h; 600° C. for 4 h; reduction at 4.6% aluminium (5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 2 h 10° C. /min; I flow rate: 30 mL/min CAT-I-7 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-50 pored acetate for 48 h; 300° C. for 6 h; reduction at 4.5% aluminium (5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 5° C./min heating rate: microsphere for 4 h 10° C. /min; I flow rate: 30 mL/min CAT-I-8 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-45 pored acetate for 48 h; 800° C. for 4 h; reduction at 4.5% aluminium (5 intermittent heating rate: 900° C. for 4 h; oxide mmol) ultrasound 10° C./min heating rate: microsphere for 4 h 10° C. /min; I flow rate: 30 mL/min CAT-I-9 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-40 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.5% aluminium (5 intermittent heating rate: 600° C. for 10 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 4 h 5° C. /min; I flow rate: 20 mL/min CAT-I-10 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-50 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.5% aluminium (5 intermittent heating rate: 1000° C. for 2 h; oxide mmol) ultrasound 1° C./min heating rate: microsphere for 4 h 20° C. /min; I flow rate: 80 mL/min CAT-I-11 hierarchical nickel impregnation calcination at 30% H.sub.2/70%N.sub.2, Ni: 10-45 pored acetate for 48 h; 600° C. for 4 h; mixed gas, 4.5% aluminium (5 intermittent heating rate: reduction at oxide mmol) ultrasound 1° C./min 900° C. for 4 h; microsphere for 4 h heating rate: I 10° C. /min; flow rate: 50 mL/min CAT-II-1 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-35 pored acetate for 48 h; 600° C. for 4 h; reduction at 3.82% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 2.05% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-2 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-30 pored acetate for 48 h; 600° C.for 4 h; reduction at 3.33% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 3.52% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (3 mmol) mL/min CAT-II-3 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-25 pored acetate for 48 h; 600° C. for 4 h; reduction at 2.91% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 8.66% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (5 mmol) mL/min CAT-II-4 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-30 pored acetate for 48 h; 600° C. for 4 h; reduction at 3.76% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 2.13% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-5 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-30 pored acetate for 48 h; 600° C. for 4 h; reduction at 3.45% aluminium (5 intermittent heating rate: 900° C. for 4 h; Ce: oxide mmol) ultrasound 1° C./min heating rate: 3.37% microsphere cerous for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-6 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-25 pored acetate for 48 h; 600° C. for 4 h; reduction at 2.04% aluminium (2.5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 2.26% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-7 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-40 pored acetate for 48 h; 600° C. for 4 h; reduction at 5.63% aluminium (7.5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 1.95% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-8 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-35 pored nitrate for 48 h; 600° C. for 4 h; reduction at 3.85% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol); ultrasound 1° C./min heating rate: 2.01% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-9 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-30 pored acetate for 24 h; 600° C. for 4 h; reduction at 3.65% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 1.93% microsphere erbium for 10 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-10 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-45 pored acetate for 96 h; 600° C. for 4 h; reduction at 4.15% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 2.13% microsphere erbium for 2 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-11 hierarchical nickel impregnation: calcination at high purity H.sub.2, Ni: 10-40 pored acetate 48 h; 300° C. for 6 h; reduction at 3.85% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 5° C./min heating rate: 2.02% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-12 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-30 pored acetate for 48 h; 800° C. for 2 h; reduction at 3.91% aluminium (5 intermittent heating rate: 900° C. for 4 h; Er: oxide mmol) ultrasound 10° C./min heating rate: 2.10% microsphere erbium for 4 h 10° C. /min; II nitrate flow rate: 30 (1 mmol) mL/min CAT-II-13 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-35 pored acetate for 48 h; 600° C. for 4 h; reduction 3.85% aluminium (5 intermittent heating rate: 600° C. for 10 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 2.06% microsphere erbium for 4 h 5° C. /min; II nitrate flow rate: 20 (1 mmol) mL/min CAT-II-14 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni: 10-40 pored acetate for 48 h; 600° C. for 4 h; reduction at 3.84% aluminium (5 intermittent heating rate: 1000° C. for 2 h; Er: oxide mmol) ultrasound 1° C./min heating rate: 2.03% microsphere erbium for 4 h 20° C. /min; II nitrate flow rate: 80 (1 mmol) mL/min CAT-II-15 hierarchical nickel impregnation calcination at 30% H.sub.2/70% N.sub.2, Ni: 10-35 pored acetate for 48 h; 600° C. for 4 h; mixed gas, 3.79% aluminium (5 intermittent heating rate: reduction at Er: oxide mmol) ultrasound 1° C./min 900° C. for 4 h; 2.01% microsphere erbium for 4 h heating rate: II nitrate 10° C. /min; (1 mmol) flow rate: 50 CAT-III-1 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  5-15 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.18% aluminium (5 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 0.43% microsphere platinum for 4 h 10° C. /min; III tetrachloride(0.5 flow rate: 30 mmol) mL/min CAT-III-2 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.09% aluminium (5 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 0.38% microsphere platinum for 4 h 10° C. /min; Er: III tetrachloride flow rate: 30 0.36% (0.5 mmol); mL/min erbium nitrate (0.5 mmol) CAT-III-3 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.05% aluminium (5 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 0.33% microsphere platinum for 4 h 10° C. /min; K: III tetrachloride flow rate: 30 0.87% (0.5 mmol); mL/min potassium nitrate (1 mmol) CAT-III-4 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.12% aluminium (5 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 0.29% microsphere platinum for 4 h 10° C. /min; Mg: III tetrachloride(0.5 flow rate: 30 0.95% mmol); mL/min mganesium chloride (1 mmol) CAT-III-5 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-5 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.16% aluminium (5 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 0.31% microsphere platinum for 4 h 10° C. /min; Er: III tetrachloride flow rate: 30 0.86% (0.5 mmol); mL/min K: erbium 0.97% nitrate (1 Mg: mmol) 0.82% potassium nitrate (1 mmol); magnesium chloride (1 mmol) CAT-III-6 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored chloride for 48 h; 600° C. for 4 h; reduction at 1.76% aluminium (2 intermittent heating rate: 900° C. for 4 h; Au: oxide mmol); ultrasound 1° C./min heating rate: 2.93% microsphere chloroauric for 4 h 10° C. /min; III acid (3 flow rate: 30 mmol) mL/min CAT-III-7 hierarchical nickel impregnation calcination at high purity H.sub.2, Ni:  1-10 pored acetate for 48 h; 300° C. for 6 h; reduction at 4.736% aluminium (5 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol) ultrasound 5° C./min heating rate: 0.54% microsphere platinum for 4 h 10° C. /min; III tetrachloride flow rate: 30 (1 mmol); mL/min CAT-III-8 hierarchical iron impregnation calcination at high purity H.sub.2, Fe:  1-10 pored nitrate for 48 h; 600° C. for 4 h; reduction at 2.76% aluminium (1 intermittent heating rate: 900° C. for 4 h; Ru: oxide mmol); ultrasound 1° C./min heating rate: 0.54% microsphere ruthenium for 4 h 10° C. /min; III acetylacetonate flow rate: 30 (2 mmol) mL/min CAT-III-9 hierarchical cobalt impregnation calcination at 30% H.sub.2/70% N.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; mixed gas, 4.02% aluminium (5 intermittent heating rate: reduction at Pt: oxide mmol); ultrasound 1° C./min 900° C. for 4 h; 0.42% microsphere platinum for 4 h heating rate: Ni: III tetrachloride 10° C. /min; 1.39% (0.5 mmol); flow rate: 50 nickel mL/min acetate (2 mmol) CAT-III-10 hierarchical cobalt impregnation calcination at 30% H.sub.2/70% N.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; mixed gas, 4.12% aluminium (5 intermittent heating rate: reduction at Pt: oxide mmol); ultrasound 1° C./min 900° C. for 4 h; 0.37% microsphere platinum for 4 h heating rate: Ni: III tetrachloride 10° C. /min; 1.33% (0.5 mmol); flow rate: 50 La: nickel mL/min 5.87 acetate (2 mmol) lanthanum nitrate (6 mmol) CAT-III-11 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; reduction at 4.03% aluminium (5 intermittent heating rate: 600° C. for 10 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 0.39% microsphere platinum for 4 h 5° C. /min; Fe: III tetrachloride flow rate: 20 2.46% (0.5 mmol); mL/min iron nitrate (3 mmol) CAT-III-12 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; reduction at 3.23% aluminium (4 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 0.24% microsphere platinum for 4 h 10° C. /min; Fe: III tetrachloride flow rate: 30 1.87% (1 mmol); mL/min K: iron 4.85% nitrate (2 mmol) potassium chloride (5 mmol) CAT-III-13 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored acetate for 48 h; 800° C. for 2 h; reduction at 3.93% aluminium (5 intermittent heating rate: 900° C. for 4 h; Pt: oxide mmol); ultrasound 10° C./min heating rate: 0.33% microsphere platinum for 4 h 10° C. /min; Fe: III tetrachloride flow rate: 30 1.23% (0.5 mmol); mL/min Ni: iron 1.08% nitrate (1.5 mmol) nickel acetate (1 mmol) CAT-III-14 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  1-10 pored acetate for 48 h; 600° C. for 4 h; reduction at 2.75% aluminium (3 intermittent heating rate: 1000° C. for 2 h; Pt: oxide mmol); ultrasound 1° C./min heating rate: 1.07% microsphere platinum for 4 h 20° C. /min; Fe: III tetrachloride flow rate: 80 0.34% (2 mmol); mL/min Ni: iron 0.75% nitrate Mg: (0.5 mmol) 4.77% nickel acetate (1 mmol) magnesium nitrate (5 mmol) CAT-III-15 hierarchical iron impregnation calcination at high purity H.sub.2, Fe:  1-10 pored nitrate for 48 h; 600° C. for 4 h; reduction at 3.93% aluminium (6 intermittent heating rate: 1000° C. for 2 h; Ru: oxide mmol) ultrasound 1° C./min heating rate: 0.75% microsphere Ruthenium for 4 h 20° C. /min; K: III acetylacetonate flow rate: 80 2.11% (0.2 mmol); mL/min potassium chloride (2 mmol) CAT-III-16 hierarchical iron impregnation calcination at high purity H.sub.2, Fe:  5-15 pored nitrate for 48 h; 600° C. for 4 h; reduction at 3.93% aluminium (6 intermittent heating rate: 1000° C. for 2 h; Rh: oxide mmol) ultrasound 1° C./min heating rate: 0.36% microsphere rhodium for 4 h 20° C. /min; La: III chloride flow rate: 80 2.11% (0.5 mmol); mL/min lanthanum nitrate (2 mmol) CAT-III-17 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co: 10-35 pored acetate for 48 h; 600° C. ° C. reduction at 4.42% aluminium (5 mmol); intermittent for 4 h; 900° C. for 4 h; oxide ultrasound heating rate: heating rate: microsphere for 4 h 1° C./min 10° C. /min; III flow rate: 30 mL/min CAT-III-18 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co: 10-40 pored acetate for 48 h; 600° C. ° C. reduction at 4.05% aluminium (5 mmol); intermittent for 4 h; 900° C. for 4 h; Er: oxide erbium ultrasound heating rate: heating rate: 1.39% microsphere acetate for 4 h 1° C./min 10° C. /min; III (1 mmol) flow rate: 30 mL/min CAT-III-19 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  5-30 pored acetate for48 h; 600° C. reduction at 4.26% aluminium (5 mmol); intermittent for 4 h; 900° C. for 4 h; La: oxide lanthanum ultrasound heating rate: heating rate: 5.07% microsphere nitrate for 4 h 1° C./min 10° C. /min; III (5 mmol) flow rate: 30 mL/min CAT-III-20 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  5-35 pored acetate for 48 h; 600° C. reduction at 4.07% aluminium (5 mmol); intermittent for 4 h; 900° C. for 4 h; K: oxide potassium ultrasound heating rate: heating rate: 4.85% microsphere chloride for 4 h 1° C./min 10° C. /min; III (5 mmol) flow rate: 30 mL/min CAT-III-21 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co:  5-35 pored acetate for 48 h; 600° C. reduction at 4.36% aluminium (5 mmol); intermittent for 4 h; 900° C. for 4 h; Mg: oxide magnesium ultrasound heating rate: heating rate: 4.82% microsphere chloride for 4 h 1° C./min 10° C. /min; III (5 mmol) flow rate: 30 mL/min CAT-III-22 hierarchical cobalt impregnation calcination at high purity H.sub.2, Co: 10-40 pored sulfate for 48 h; 300° C. reduction at 2.85% aluminium (3 mmol); intermittent for 6 h; 900° C. for 4 h; oxide ultrasound heating rate: heating rate: microsphere for 4 h 5° C./min 10° C. /min; III flow rate: 30 mL/min CAT-III-23 hierarchical cobalt impregnation calcination at high purity H.sub.2, Fe: 10-35 pored nitrate for 48 h; 600° C. reduction at 4.63% aluminium (5 mmol) intermittent for 4 h; 900° C. for 4 h; oxide ultrasound heating rate: heating rate: microsphere for 4 h 1° C./min 10° C. /min; III flow rate: 30 mL/min CAT-III-24 hierarchical iron impregnation calcination at 30% H.sub.2/70% N.sub.2, Fe: 10-35 pored nitrate for 48 h; 600° C. mixed gas, 3.89% aluminium (6 mmol) intermittent for 4 h; reduction at Ni: oxide nickel acetate ultrasound heating rate: 900° C. for 4 h; 1.24% microsphere (2 mmol) for 4 h 1° C./min heating rate: III 10° C. /min; flow rate: 50 mL/min CAT-III-25 hierarchical iron impregnation calcination at 30% H.sub.2/70% N.sub.2, Fe: 10-40 pored nitrate for 48 h; 600° C. mixed gas, 4.79% aluminium (6 mmol) intermittent for 4 h; reduction at Co: oxide cobalt acetate ultrasound heating rate: 900° C. for 4 h; 1.24% microsphere (2 mmol) for 4 h 1° C./min heating rate: III 10° C. /min; flow rate: 50 mL/min CAT-III-26 hierarchical iron impregnation calcination at high purity H.sub.2, Fe: 10-45 pored nitrate for 48 h; 600° C. reduction at 1.84% aluminium (2 mmol) intermittent for 4 h; 600° C. for 10 h; Co: oxide cobalt ultrasound heating rate: heating rate: 1.92% microsphere acetate for 4 h 1° C./min 5° C. /min; Er: III (2 mmol); flow rate: 20 1.68% nickel mL/min acetate (2 mmol) CAT-III-27 hierarchical iron impregnation calcination at high purity H.sub.2, Fe: 10-35 pored nitrate for 48 h; 600° C. reduction at 2.04% aluminium (2.5 mmol) intermittent for 4 h; 900° C. for 4 h; Co: oxide cobalt ultrasound heating rate: heating rate: 1.97% microsphere acetate for 4 h 1° C./min 10° C. /min; Er: III (3 mmol); flow rate: 30 1.26% erbium mL/min nitrate (1 mmol) CAT-III-28 hierarchical cobalt impregnation calcination at high purity H.sub.2, Fe: 10-35 pored acetate for 48 h; 800° C. reduction at 2.91% aluminium (3 mmol) intermittent for 2 h; 900° C. for 4 h; Ni: oxide nickel ultrasound heating rate: heating rate: 2.39% microsphere acetate for 4 h 10° C./min 10° C. /min; K: III (3 mmol); flow rate: 30 1.32% potassium mL/min chloride (1 mmol) CAT-III-29 hierarchical iron impregnation calcination at high purity H.sub.2, Fe:  5-35 pored nitrate for 48 h; 600° C. reduction at 3.93% aluminium (6 mmol) intermittent for 4 h; 1000° C. for 2 h; Mg: oxide magnesium ultrasound heating rate: heating rate: 2.11% microsphere chloride for 4 h 1° C./min 20° C. /min; Er: III (2 mmol); flow rate: 80 1.38% erbium mL/min nitrate (1 mmol)

Example 2 Characterization of the Samples

(21) Scanning electron microscopes are used for the characterizations of hierarchical pored aluminium oxide microsphere I, hierarchical pored aluminium oxide microsphere II and hierarchical pored aluminium oxide microsphere III. As the typical sample, the cross-sectional SEM images of the hierarchical pored aluminium oxide microsphere I were shown in FIG. 1. It can be seen that hierarchical pored aluminium oxide microspheres possess micron-sized macropores and nanopores. The SEM images of hierarchical pored aluminium oxide microsphere II and hierarchical pored aluminium oxide microsphere III are similar with FIG. 1.

(22) Transmission electron microscope was used to observe the particle sizes of active components and modification components rare earth particles on the catalyst. The results of the particle sizes are shown in Table 1.

(23) ICP was used to determine the percentage contents of iron group elements, noble metal elements, alkali metal elements, alkaline earth metal elements and rare earth elements in the samples. The results are shown in Table 1.

Example 3 Catalytic Properties of Sample CAT-I-1˜CAT-I-11

(24) 0.2 g of catalyst CAT-I-1 was put into a fixed bed reactor with an inner diameter of 1 cm, and reducted online by hydrogen. The temperature of the reactor was adjusted to the reaction temperature subsequently. The reducing gas was switched to a mixed gas of CO.sub.2 and CH.sub.4, wherein N.sub.2 was used as an internal standard. The reacted gas was cooled down and the contents of each substance therein were determined by gas chromatography. Conversions of CO.sub.2 and CH.sub.4 were calculated.

(25) Relationships between reaction conditions and the conversions of CO.sub.2 and CH.sub.4 are shown in Table 2.

(26) When the reaction condition was A, the chromatography results of the tail gas was shown in FIG. 2. It can be seen from FIG. 2 that, the catalyst provided by the present application has good selectivity, and the product was mainly consisted of hydrogen and carbon monoxide, which are the major constituents of syngas.

(27) TABLE-US-00002 TABLE 2 Conditions Composition Reaction for hydrogen and flow condition online rate of raw Reaction Reaction Conversion Conversion No. reduction gas temperature pressure rate of CO.sub.2 rate of CH.sub.4 A high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 82.52% 64.91% reduction at 47: 47: 6 800° C. for1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min B 80% H.sub.2/20% CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 83.64% 65.57% N.sub.2mixed gas, 47: 47: 6 reduction at flow rate: 30 850° C. for 2 h; mL/min heating rate: 20° C./min flow rate: 30 mL/min C high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 90.37% 38.28% reduction at 31: 62: 7 800° C. for 1 h; flow rate: 50 heating rate: mL/min 10° C./min; flow rate: 15 mL/min D high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 41.34% 92.46% reduction at 62: 31: 6 800° C. for 1 h; flow rate: 50 heating rate: mL/min 10° C./min; flow rate: 15 mL/min E high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 600° C. 0.1 MPa 18.37%  8.41% reduction at 47: 47: 6 800° C. for 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min F high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 850° C. 0.1 MPa 92.97% 84.13% reduction at 47: 47: 6 800° C. for 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min G high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.5 MPa 93.65% 75.39% reduction at 47: 47: 6 800° C. for1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min

(28) Conversion rates of CO.sub.2 and CH.sub.4 are calculated by the following equation respectively:

(29) ${\mathrm{CO}}_2\%=\frac{F_{\mathrm{CO}2,\mathrm{in}}-F_{\mathrm{CO}2,\mathrm{out}}}{F_{\mathrm{CO}2,\mathrm{in}}}\times 100\%$${\mathrm{CH}}_4\%=\frac{F_{\mathrm{CH}4,\mathrm{in}}-F_{\mathrm{CH}4,\mathrm{out}}}{F_{\mathrm{CH}4,\mathrm{in}}}\times 100\%$

(30) wherein F.sub.CO2, in and F.sub.CO2, out are respectively volume flows of CO.sub.2 in the raw gas and reaction tail gas; F.sub.CH4, in and F.sub.CH4, out are respectively volume flows of CH.sub.4 in the reactant and the product.

(31) Under the same reaction conditions, catalyst CAT-I-2˜CAT-I-11 provided similar results as CAT-I-1, and the conversion rates of CO.sub.2 and CH.sub.4 vary in a range of ±10% on the basis of the difference in the preparation methods of the catalysts.

Example 4 Evaluation on the Catalyst Stability of Samples CAT-I-1˜CAT-I-11

(32) 0.2 g of catalyst CAT-I-1 was put into a fixed bed reactor with an inner diameter of 1 cm. The evaluation on the catalyst stability is carried out under the reaction condition A in Example 3, and the result is shown in FIG. 3. It can be seen from FIG. 3 that, CAT-I-1 possesses excellent stability under atmospheric pressure and at 800° C., and the conversion rates of carbon dioxide and methane nearly maintain unchanged within the first 100 hours of reaction.

(33) Transmission electron microscope images of CAT-I-1 tested before and after the reaction are shown in FIG. 4. FIG. 4(a) is the transmission electron microscopy image of CAT-I-1 tested before the reaction; FIG. 4(b) is the transmission electron microscopy image of CAT-I-1 tested after reacting for 102 hours at 800° C. It can be seen from FIG. 4 that, nickel particles, as the active component on the catalyst, nearly did not change after the reaction and had not been sintered; moreover, no deposited carbon was generated in the catalyst within 102 hours.

(34) Under the same reaction conditions, the results of evaluation on the catalyst stability of CAT-I-2˜CAT-I-11 are similar to that of CAT-I-I, and the conversion rates of carbon dioxide and methane nearly maintain unchanged within the first 100 hours. Transmission electron microscopy images of samples CAT-I-2˜CAT-I-11 before and after 102 hours of reaction at 800° C. show the similar comparison results as CAT-1-1. The nickel particle had not been sintered, and no deposited carbon was generated in the catalyst.

Example 5 Preparation of Catalyst DCAT-II-1

(35) 5 mmol of nickel acetate was dissolved in 10 mL water to form a solution, and 5 g of hierarchical pored aluminium oxide microsphere II was added. After being impregnated for 48 h (ultrasonic was conducted for 4 h intermittently), water and surplus nickel acetate that had not been absorbed were filtered out. After being vacuum dried at 80° C. for 8 h, aluminium oxide absorbed the nickel ion was calcinated at 600° C. for 4 h in air atmosphere (the heating rate was 1° C./min), followed by reduction for 4 h at 900° C. using high purity hydrogen (the heating rate was 10° C./min). The obtained sample was denoted as catalyst DCAT-II-1. The mass percentage content of nickel in DCAT-II-1 is 4.25%.

Example 6 Comparison on the Activity Between CAT-II-1 and DCAT-II-1

(36) Each 0.2 g of catalyst samples CAT-II-1 and DCAT-II-1 was put into a fixed bed reactor with inner diameter of 1 cm, and high purity H.sub.2 with a flow rate of 5 mL/min was continuously introduced into the reactor, and then the reactor was heated to 800° C. with a heating rate of 10° C./min and hydrogen online reduction of the catalyst was carried out for 1 h. 30 mL/min of raw gas (molar ratio of CO.sub.2:CH.sub.4:N.sub.2=47:47:6) was introduced, and the reaction pressure was kept at 0.1 MPa, and the temperature was adjusted to 600° C., then the reaction temperature was raised gradually to 850° C. with a heating rate of 10° C./min. The comparison of the conversion rates of carbon dioxide and methane on catalyst CAT-II-1 and DCAT-II-1 at different reaction temperature was shown in FIG. 5.

(37) Mass percentage content of nickel in CAT-II-1 is 3.82%; mass percentage content of nickel in CAT-II-1 is 4.25%. It can be seen from FIG. 5 that being introduced with modification rare earth elements, the catalyst CAT-II-1 with a lower content of the active component, had a better perform on the conversion rates of carbon dioxide and methane than DCAT-II-1 with higher component content.

Example 7 Evaluation on the Catalytic Properties of Samples CAT-II-1˜CAT-II-15

(38) 0.2 g of catalyst CAT-II-1 was put into a fixed bed reactor with an inner diameter of 1 cm, after hydrogen online reduction, the temperature of the reactor was adjusted to the reaction temperature. The gas was switched to a mixed gas of CO.sub.2 and CH.sub.4, wherein N.sub.2 was used as an internal standard. The reacted gas was cooled down and the contents of each substance were determined by gas chromatography. Conversions of CO.sub.2 and CH.sub.4 were calculated.

(39) Relationships between reaction conditions and the conversions of CO.sub.2 and CH.sub.4 are shown in Table 3.

(40) When the reaction condition was A, the chromatography results of the tail gas were shown in FIG. 6. It can be seen from FIG. 6 that, the catalyst provided by the present application has good selectivity, and the product was mainly consisted of hydrogen and carbon monoxide, which are the major constituents of syngas.

(41) TABLE-US-00003 TABLE 3 Conditions Composition Reaction for hydrogen and flow condition online rate of raw Reaction Reaction Conversion Conversion No. reduction gas temperature pressure rate of CO.sub.2 rate of CH.sub.4 A high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 83.15% 71.34% reduction at 47: 47: 6 800° C.for 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min B 80% H.sub.2/20% N.sub.2 CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 85.23% 73.15% mixed gas, 47: 47: 6 reduction at flow rate: 30 850° C. for 2 h; mL/min heating rate: 20° C./min flow rate: 30 mL/min C high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 91.35% 39.61% reduction at 31: 62: 7 800° C. for 1 h; flow rate: 50 heating rate: mL/min 10° C./min; flow rate: 15 mL/min D high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 53.72% 89.23% reduction at 62: 31: 6 800° C. for 1 h; flow rate: 50 heating rate: mL/min 10° C./min; flow rate: 15 mL/min E high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 600° C. 0.1 MPa 23.35% 15.81% reduction at 47: 47: 6 800° C. for 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min F high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 850° C. 0.1 MPa 93.25% 85.62% reduction at 47: 47: 6 800° C. for 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min G high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.5 MPa 92.34% 85.36% reduction at 47: 47: 6 800° C. for 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min

(42) Conversion rates of CO.sub.2 and CH.sub.4 are calculated by the following equation respectively:

(43) ${\mathrm{CO}}_2\%=\frac{F_{\mathrm{CO}2,\mathrm{in}}-F_{\mathrm{CO}2,\mathrm{out}}}{F_{\mathrm{CO}2,\mathrm{in}}}\times 100\%$${\mathrm{CH}}_4\%=\frac{F_{\mathrm{CH}4,\mathrm{in}}-F_{\mathrm{CH}4,\mathrm{out}}}{F_{\mathrm{CH}4,\mathrm{in}}}\times 100\%$

(44) wherein F.sub.CO2, in and F.sub.CO2, out are respectively volume flows of CO.sub.2 in the raw gas and reaction tail gas; F.sub.CH4, in and F.sub.CH4, out are respectively volume flows of CH.sub.4 in the reactant and the product.

(45) Under the same reaction conditions, catalyst CAT-II-2˜CAT-II-15 provided similar results as CAT-II-1, and the conversion rates of CO.sub.2 and CH.sub.4 vary in a range of ±10% on the basis of the difference in the preparation methods of the catalysts.

Example 8 Evaluation on the Stability of Samples CAT-II-1˜CAT-II-15

(46) 0.2 g of catalyst CAT-II-1 was put into a fixed bed reactor with an inner diameter of 1 cm. The evaluation on the catalyst stability was carried out under the reaction condition A in Example 7. The result is shown in FIG. 7. It can be seen from FIG. 7 that, the catalyst provided by the present application possesses excellent stability under atomospheric pressure and at 800° C., and the conversion rates of carbon dioxide and methane nearly maintain unchanged within the first 100 hours of reaction.

(47) Transmission electron microscope images of CAT-II-1 tested before and after the reaction are shown in FIG. 8. FIG. 8(a) is the transmission electron microscopy image of CAT-II-1 tested before the reaction; FIG. 8(b) is the transmission electron microscopy image of CAT-II-1 tested after reacting for 102 hours at 800° C. It can be seen from FIG. 8 that, nickel particles, the active component on the catalyst, nearly did not change after the reaction and had not been sintered; moreover, no deposited carbon was generated in the catalyst within 102 hours.

(48) Under the same reaction conditions, the results of evaluation on the catalyst stability of CAT-II-2˜CAT-II-15 are similar to that of CAT-II-I, and the conversion rates of carbon dioxide and methane nearly maintain unchanged within the first 100 hours. Transmission electron microscopy images of samples CAT-II-2˜CAT-I-15 before and after 102 hours of reaction at 800° C. show the similar comparison results as CAT-II-1, the nickel particle had not been sintered and no deposited carbon was generated in the catalyst.

Example 9 Evaluation on the Catalytic Properties of Samples CAT-III-1˜CAT-III-2

(49) 0.2 g of catalyst CAT-III-1 was put into a fixed bed reactor with an inner diameter of 1 cm, after hydrogen online reduction, the temperature of the reactor was adjusted to the reaction temperature. The reduction gas was switched to a mixed gas of CO.sub.2 and CH.sub.4, wherein N.sub.2 was used as an internal standard. The reacted gas was cooled down and the contents of each substance therein were determined by gas chromatography. Conversions of CO.sub.2 and CH.sub.4 were calculated.

(50) Relationships between reaction conditions and the conversions of CO.sub.2 and CH.sub.4 are shown in Table 4.

(51) TABLE-US-00004 TABLE 4 Conditions Composition Reaction for hydrogen and flow condition online rate of raw Reaction Reaction Conversion Conversion No. reduction gas temperature pressure rate of CO.sub.2 rate of CH.sub.4 A high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 88.43% 75.98% 800° C. 47: 47: 6 reduction 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min B 80% H.sub.2/20% N.sub.2 CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 87.98% 74.28% mixed gas, 47: 47: 6 850° C. flow rate: 30 reduction 2 h; mL/min heating rate: 20° C./min flow rate: 30 mL/min C high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 93.87% 42.87% 800° C. 31: 62: 7 reduction 1 h; flow rate: 50 heating rate: mL/min 10° C./min; flow rate: 15 mL/min D high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.1 MPa 62.76% 92.98% 800° C. 62: 31: 6 reduction 1 h; flow rate: 50 heating rate: mL/min 10° C./min; flow rate: 15 mL/min E high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 600° C. 0.1 MPa 29.90% 18.26% 800° C. 47: 47: 6 reduction 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min F high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 900° C. 0.1 MPa 95.47% 87.86% 800° C. 47: 47: 6 reduction 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min G high purity H.sub.2, CO.sub.2: CH.sub.4: N.sub.2 = 800° C. 0.5 MPa 94.27% 86.73% 800° C. 47: 47: 6 reduction 1 h; flow rate: 30 heating rate: mL/min 10° C./min; flow rate: 15 mL/min

(52) Conversion rates of CO.sub.2 and CH.sub.4 are calculated by the following equation respectively:

(53) ${\mathrm{CO}}_2\%=\frac{F_{\mathrm{CO}2,\mathrm{in}}-F_{\mathrm{CO}2,\mathrm{out}}}{F_{\mathrm{CO}2,\mathrm{in}}}\times 100\%$${\mathrm{CH}}_4\%=\frac{F_{\mathrm{CH}4,\mathrm{in}}-F_{\mathrm{CH}4,\mathrm{out}}}{F_{\mathrm{CH}4,\mathrm{in}}}\times 100\%$

(54) wherein F.sub.CO2, in and F.sub.CO2, out are respectively volume flows of CO.sub.2 in the raw gas and reaction tail gas; F.sub.CH4, in and F.sub.CH4, out are respectively volume flows of CH.sub.4 in the reactant and the product.

(55) Under the same reaction conditions, catalyst CAT-III-2˜CAT-III-29 provided similar results as CAT-III-1, and the conversion rates of CO.sub.2 and CH.sub.4 vary in a range of ±20% on the basis of the difference in the preparation methods of the catalysts.

Example 10 Evaluation on the Stability of Samples CAT-III-1˜CAT-III-2

(56) Each 0.2 g of sample catalysts CAT-III-1, CAT-III-2 and CAT-III-17 were added to fixed bed reactors with an inner diameter of 1 cm. The evaluation was carried out under the reaction condition A in Example 9.

(57) The stability test results of catalysts CAT-III-1, CAT-III-2 and CATA-III-17 are shown in FIG. 9(a) and FIG. 9(b). It can be seen from FIG. 9 that, CAT-III-1 and CAT-III-2, which contained noble metals and iron group metals in their active elements, maintain a relatively good stability in the conversion rates of carbon dioxide and methane under atmospheric pressure and at 800° C. within 204 hours of the reaction. Those catalysts did not contain noble metals provided a slightly lower stability. The stability of the catalyst: CAT-III-2>CAT-III-1>CAT-III-17, which means that the addition of the noble metals improve the stability of the catalyst. At the same time, the data in FIG. 9(a) and FIG. 9(b) indicate that, except for the improvement of the stability, the conversion rates of carbon dioxide and methane are also significantly raised after the introduction of noble metals to the catalyst. Furthermore, after modified by adding a small quantity of rare earth elements, the conversion rates were also slightly raised.

Example 11 the Effect of Adding Noble Metals

(58) As the typical sample, the transmission electron microscopy image of CAT-III-1 was shown in FIG. 10(a). It can be seen from FIG. 10 that, on the catalyst containing noble metals, the metal particles have uniform sizes range from 5 nm to 15 nm, and the metal particles are dispersed uniformly on/in the support. FIG. 10(b) and FIG. 10(c) are transmission electron microscopy images of CAT-III-17 and CA-III-18, respectively. Comparing FIG. 10(a)˜FIG. 10(c), it can be seen that, after adding rare earth elements to the non-noble metal catalyst, the particle size of the active metal particle decreases; however, after adding noble metals, the reduction in the particle size was much more bigger than that of adding rare earth elements. This well explained the reason why the sample catalysts containing noble metals provide a higher carbon dioxide and methane conversion rates. Meanwhile, small sized metallic active component particles have stronger interaction with the support, which is beneficial for enhancing the high temperature catalytic stability of the catalyst. Compared with adding modification component (such as rare earth elements), adding noble metal active component improved much more in the overall property of the iron group catalysts.

(59) The foregoing is only several examples and preferred embodiments of the present application, and is not any kind of limit to the scope of the present application. However, it can be conceived that other variations and modifications can be made without departing from the scope covered by the claims of the present application, and all of these variations and modifications fall into the scope of protection of the present application.