OXYGEN-FREE DIRECT CONVERSION OF METHANE AND CATALYSTS THEREFOR

Abstract

A process of methane catalytic conversion produces olefins, aromatics, and hydrogen under oxygen-free, continuous flowing conditions. Such a process has little coke deposition and realizes atom-economic conversion. Under the conditions encountered in a fixed bed reactor (i.e. reaction temperature: 750-1200 C.; reaction pressure: atmospheric pressure; the weight hourly space velocity of feed gas: 1000-30000 ml/g/h; and fixed bed), conversion of methane is 8-50%. The selectivity of olefins is 30-90%. And selectivity of aromatics is 10-70%. The catalyst for this methane conversion has a SiO.sub.2-based matrix having active species that are formed by confining dopant metal atoms in the lattice of the matrix.

Claims

1. A catalyst, comprising: a matrix of SiO.sub.2, Si3N4, SiC, SiCxOy (in which 4x+2y=4), SiOyNz (in which 2y+3z=4), SiCxNz (in which 4x+3z=4), or SiCxOyNz (in which 4x+2y+3z=4), one or more embedded metal dopants confined in the matrix, a plurality of active species, each of the plurality of active species is formed by replacing a Si, C, O, or N atom in the matrix with an atom of metal dopant, wherein an amount of the embedded metal dopant ranges from 0.001 wt % to 5 wt % to of a total weight of the catalyst, wherein x ranges from 0 to 1, y ranges from 0 to 2, and z ranges from 0 to 4/3, wherein the embedded metal dopant is selected from a group consisting of Li, Na, K, Mg, Al, Ca, Sr, Ba, Y, La, Ti, Zr, Ce, Cr, Mo, W, Re, Fe, Co, Ni, Cu, Zn, Ge, In, Sn, Pb, Bi, Mn, Ru, Pt, Au, and mixtures thereof.

2. The catalyst according to claim 1, wherein the catalyst further comprises one or more metals or metal compounds supported on a surface of the matrix, wherein the supported metal compound is selected from the group consisting of metal oxides, metal carbides, metal nitrides, metal silicides, and metal silicates.

3. The catalyst according to claim 2, wherein the supported metal or the metal in the supported metal compound is selected from the group consisting of Li, Na, K, Mg, Al, Ca, Sr, Ba, Y, La, Ti, Zr, Ce, Cr, Mo, W, Re, Fe, Co, Ni, Cu, Zn, Ge, In, Sn, Pb, Bi, and Mn.

4. The catalyst according to claim 1, wherein the catalyst is prepared by a chemical vapor deposition method comprising mixing silicon vapor or SiCl.sub.4 with a vapor of the embedded metal dopant or a vapor of a volatile salt of the embedded metal dopant; and reacting the mixture with a water vapor to obtain a solid.

5. The catalyst according to claim 1, wherein the catalyst is prepared by a vapor phase axial deposition method comprising mixing silicon vapor or SiCl.sub.4 with a vapor of the embedded metal dopant or a vapor of a volatile salt of the embedded metal dopant; exposing a substrate of corundum, silicon carbide, or silicon nitride to the mixture; and reacting the mixture with a water vapor to form a solid deposited on the substrate.

6. The catalyst according to claim 5, wherein the volatile metal salt is selected from the group consisting of metal carbonyls, metal alkoxides of carbon atom number from 1 to 5, and metal organic acid salts of C atom number from 1 to 5.

7. The catalyst according to claim 1, wherein the catalyst is in a form of particles of size in the range of 10 nm-10 cm.

8. The catalyst according to claim 1, wherein the amount of the embedded metal dopants ranges from 0.5 wt % to 2.0 wt % of a total weight of the catalyst.

9. The catalyst according to claim 1, wherein the individual metal dopant atom of the embedded metal in each of the plurality of active species bonds with atoms adjacent to the replaced Si, C, O, or N atom.

10. The catalyst according to claim 1, wherein the embedded metal dopant is a transition metal.

11. The catalyst according to claim 1, wherein the dopant embedded metal is selected from the group consisting of Fe, Co, Ni, Au, Pt, Ru, Ce, La, and combinations thereof.

12. The catalyst according to claim 1, wherein the matrix is SiO.sub.2.

13. A method for converting methane to olefins, comprising: reacting a methane feedstock comprising methane in presence of a catalyst of claim 1; and obtaining a product stream comprising olefins, aromatics, and hydrogen.

14. The method according to claim 13, wherein a reaction temperature ranges from 750 C. and 1200 C.

15. The method according to claim 13, further comprising a step of pretreating the catalyst in a feed gas comprising hydrocarbons selected from the group consisting of alkanes with 2 to 10 carbon atoms, alkenes with 2 to 10 carbon atoms, alkyne with 2 to 10 carbon atoms, monohydric alcohol with 1 to 10 carbon atoms, dihydric alcohol with 2 to 10 carbon atoms, aldehyde with 1 to 10 carbon atoms, carboxylic acid with 1 to 10 carbon atoms, and aromatics with 6 to 10 carbon atoms, at a temperature ranging from 800 C. to 1000 C. under a pressure ranging from 0.1 MPa to 1 MPa in a weight hourly space velocity of feed gas ranging from 500 ml/g/h to 3000 ml/g/h.

16. The method according to claim 13, wherein the methane feedstock comprises methane, optionally an inert gas, optionally a non-inert gas, and is substantially oxygen free, wherein the inert gases is selected from a group consisting of nitrogen (N.sub.2), helium (He), neon (Ne), argon (Ar), krypton (Ke), and a mixture thereof, wherein the non-inert gases is selected from a group consisting carbon monoxide (CO), hydrogen (H.sub.2), carbon dioxide (CO.sub.2), water vapor (H.sub.2O), monohydric alcohol with 1 to 5 carbon atoms, dihydric alcohol with 2 to 5 carbon atoms, alkanes with 2 to 8 carbon atoms, and a mixture thereof, and wherein the methane feedstock comprises 5-100% of methane by volume, 0-95% of the inert gas by volume, and 0-15% of the non-inert gas by volume.

17. The method according to claim 13, wherein the conversion of methane is carried out in a fluidized bed, a moving bed, or a fixed bed, at a pressure ranging from 0.05 MPa to 1 MPa, and a weight hourly space velocity of the methane feedstock ranging from 1000 ml/g/h to 30000 ml/g/h.

18. A method for preparing the catalyst of claim 1, comprising: dissolving a liquid silicon source and a metal salt selected from the group consisting of metal nitrates, metal halides, metal sulfates, metal carbonates, metal hydroxides, metal organic acid salts having 1 to 10 carbon atoms, and metal alkoxides having 1 to 10 carbon atoms in a mixture of water and ethanol wherein a weight content of water in the mixture is 10-100%; obtaining a sol gel from the mixture after hydrolysis and condensation; drying the slurry to obtain a powder; melting the powder at a temperature ranging from 1300 C. to 2000 C. to a molten mixture; cooling the molten mixture to a solid; and grinding the solid to particles.

19. A method for preparing the catalyst according to claim 14, comprising the steps of: providing a porous silicon-based material selected from the group consisting of silica, silicon carbide, silicon nitride, and a mixture thereof; impregnating the porous silicon-based material in a solution comprising a salt of the metal dopant to obtain a slurry; drying the slurry to obtain a powder; melting the powder at a temperature ranging from 1300 C. to 2000 C. to a molten mixture; and cooling the molten mixture to a solid.

Description

DESCRIPTION OF FIGURES

[0074] FIG. 1 shows the XRD pattern of 0.5 wt. % Ca-0.5 wt. % FeSiO.sub.2 catalyst.

[0075] FIG. 2 shows an XPS spectra of Fe doping 6H-SiC(0001).

[0076] FIG. 3 is a HRTEM image of the metal lattice-doping catalyst.

[0077] FIG. 4 is a HAADF-STEM image of the single-atom metal doping catalyst.

EMBODIMENTS

1. Catalyst Preparation

[0078] The preparation methods of silicon-based catalysts with metal dopants include the following solid phase doping technologies, such as Chemical Vapor Deposition (CVD), Vapour phase Axial Deposition (VAD), Laser induced Chemical Vapor Deposition (LCVD), metal doping sol-gel method, porous Si-based materials impregnation method, powder doping method and so on. The catalysts are marked as: ASiO.sub.xC.sub.yN.sub.z.

[0079] The preparation of ASiO.sub.2 catalysts (example 1, 2, 3, 4, 5, 7); the preparation of ASiOC.sub.0.5 catalysts (example 6); the preparation of ASi.sub.3C.sub.4 catalysts (example 8, 9, 10); the preparation of ASi.sub.3N.sub.4 catalysts (example 11); the preparation of ASiOC.sub.0.35N.sub.0.2 catalysts (example 12); the preparation of A/SiO.sub.2 catalysts (example 13) (Active species is highly dispersed on the support.)

Example 1

[0080] Chemical Vapor Deposition (CVD) The vapor phase in the high-temperature reaction furnace was formed by bubbling 30 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 30 mL of ethanol solution dissolving 17 g of SiCl.sub.4 and 94 mg of Co.sub.2(CO).sub.8. The mist vapor mixture sprayed from the center of combustor was hydrolyzed and melted to form a uniform SiO.sub.2 material doped with Co at 1200 C. The material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The Co doped silica catalyst, 0.5 wt. % CoSiO.sub.2, was obtained after subsequent quenching in cold water.

Example 2

Chemical Vapor Deposition (CVD)

[0081] The vapor phase in the high-temperature reaction furnace was formed by bubbling 30 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 30 mL of ethanol solution dissolving 17 g of SiCl.sub.4, 94 mg of Co.sub.2(CO).sub.8 and 86.9 mg Ni(CO).sub.4. The mist vapor mixture sprayed from the center of combustor was hydrolyzed and melted at 1200 C. to form a uniform SiO.sub.2 material doped with Co and Ni. The material was further melted at 1400 C. in vacuum (10 Pa) for 6 h. The Co/Ni doping silica catalyst, 0.5 wt. % Co-0.5 wt. % NiSiO.sub.2, was obtained after subsequent quenching in cold water.

Example 3

Vapor Phase Axial Deposition (VAD)

[0082] The vapor phase in the high-temperature reaction furnace was formed by bubbling 30 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 30 mL of ethanol solution dissolving 17 g of SiCl.sub.4, 94 mg of Co.sub.2(CO).sub.8. The mist vapor mixture sprayed from the center of combustor was hydrolyzed and axial deposited on the surface of alumina support at 1200 C. to form a uniform SiO.sub.2 material doped with Co. The material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The Co doping silica catalyst, 0.5 wt. % CoSiO.sub.2, was obtained after subsequent quenching in cold water.

Example 4

[0083] Vapor Phase Axial Deposition (VAD) The vapor phase in the high-temperature reaction furnace was formed by bubbling 30 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 30 mL of ethanol solution dissolving 17 g of SiCl.sub.4, 94 mg of Co.sub.2(CO).sub.8 and 86.9 mg Ni(CO).sub.4. The mist vapor mixture sprayed from the center of combustor was hydrolyzed and axial deposited on the surface of alumina support at 1200 C. to form a uniform SiO.sub.2 material doped with Co and Ni. The obtained material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The Co doping silica catalyst, 0.5 wt. % Co-0.5 wt. % NiSiO.sub.2, was obtained after subsequent quenching in cold water.

Example 5

Metal Doping Sol-Gel Method

[0084] A metal doping silica gel was formed by stirring 20 mL of tetraethoxysilane (TEOS), 120 mg of Co(NO.sub.3).sub.2.6H.sub.2O, 117.1 mg Ca(NO.sub.3).sub.2.4H.sub.2O and 30 mL ethanol in 24 g 15% nitric acid solution at 60 C. for 24 h. The gel was dried in rotary evaporator at 80 C. for 2 h and melted at 1400 C. in He atmosphere for 6 h. The Co/Ca doped silica catalyst, 0.5 wt. % Ca-0.5 wt. % CoSiO.sub.2, was obtained after subsequent quenching in cold water.

Example 6

[0085] The vapor phase in the high-temperature reaction furnace was formed by bubbling 30 mL/min of carrier gas (10% v of H.sub.2 and 90% v of He) into an 30 mL of ethanol solution dissolving 17 g of SiCl.sub.4 and 94 mg of Co.sub.2(CO).sub.8. The mist vapor mixture sprayed from the center of combustor was hydrolyzed and melted at 1200 C. to form a uniform SiO.sub.2 material doped with Co. The material was treated in a mixed gas (10% v of CH.sub.4 and 90% v of He) at 2000 C. and afterwards melted at 1400 C. in vacuum (10 Pa) for 6 h. The Co doped catalyst, 0.5 wt. % CoSiOC.sub.0.5, was obtained after subsequent quenching in cold water.

Example 7

Porous Si-Based Materials Impregnation Method

[0086] The catalyst was prepared by impregnating 6 g of porous silica powder in a solution of 117 mg of Ca(NO.sub.3).sub.2.4H.sub.2O and 137.3 mg of Co(NO.sub.3).sub.2.6H.sub.2O in 10 mL of water. The slurry was dried by stirring and aging for 24 h at 120 C. and afterwards melted at 1400 C. in vacuum (10 Pa) for 6 h. The Co/Ca doped catalyst, 0.5 wt. % Ca-0.5 wt. % CoSiO.sub.2, was obtained after subsequent melting process at 1400 C. in vacuum (10 Pa) for 6 h.

Example 8

Porous Si-Based Materials Impregnation Method

[0087] The metal doped was prepared by impregnating 6 g of porous silicon carbide powder in a solution of 216 mg of Fe(NO.sub.3).sub.3.9H.sub.2O in 10 mL of water. The slurry was dried by stirring and aging for 24 h at 120 C. The dry powder was melted at 2000 C. in vacuum (10 Pa) for 6 h to form a uniform SiC material doped with Fe. The Fe doping catalyst, 0.5 wt. % FeSiC, was obtained after subsequent quenching in rapeseed oil.

Example 9

[0088] A metal doped silica gel was formed by stirring 20 mL of tetraethoxysilane (TEOS), 120 mg of Co(NO.sub.3).sub.2.6H.sub.2O, 117.1 mg Ca(NO.sub.3).sub.2.4H.sub.2O and 30 mL ethanol in 24 g 15% nitric acid solution at 60 C. for 24 h. The gel was dried in rotary evaporator at 80 C. for 2 h and melted with carbon at 2000 C. for 2.5 h to form a uniform SiC material doped with Co and Ca. The Co/Ca doping silica catalyst, 0.5 wt. % Ca-0.5 wt. % CoSiOC.sub.0.5, was obtained after subsequent quenching in cold water.

Example 10

[0089] A metal doped silica gel was formed by stirring 20 mL of tetraethoxysilane (TEOS), 120 mg of Co(NO.sub.3).sub.2.6H.sub.2O, 117.1 mg Ca(NO.sub.3).sub.2.4H.sub.2O and 30 mL ethanol in 24 g 15% nitric acid solution at 60 C. for 24 h. The gel was dried in rotary evaporator at 80 C. for 2 h and calcined with carbon at 2000 C. for 12 h to form a uniform SiC material doped with Co and Ca. The Co/Ca doping silica catalyst, 0.5 wt. % Ca-0.5 wt. % CoSiC, was obtained after subsequent quenching in cold water.

Example 11

[0090] The catalyst (0.5 wt. % Ca-0.5 wt. % Co@SiO.sub.2) mentioned in example 5 was treated in nitriding furnace at 1150-1200 C. at NH.sub.3 atmosphere for 4 h and then 1350-1450 C. at NH.sub.3 atmosphere for 18-36 h, until all become far nitride to form a uniform Si.sub.3N.sub.4 material doped with Co and Ca. The resulting powder was 0.5 wt. % Ca-0.5 wt. % CoSi.sub.3N.sub.4.

Example 12

[0091] The catalyst (0.5 wt. % Co@SiOC.sub.0.5) mentioned in example 6 was treated in nitriding furnace at 1150-1200 C. at NH.sub.3 atmosphere for 4 h and then 1350-1450 C. at NH.sub.3 atmosphere for 7.5 h to form a uniform SiOC.sub.0.35N.sub.0.3 material doped with Co. The resulting powder was 0.5 wt. % Ca-0.5 wt. % CoSiOC.sub.0.35N.sub.0.3.

Example 13

[0092] The metal loading catalyst was prepared by impregnating 6 g of silica support in a solution of 94 mg of Co.sub.2(CO).sub.8 in 10 mL of water. The slurry was stirred vigorously for 12 h and aging for 24 h at 60 C. The Co loading catalyst, 0.5 wt. % Co/SiO.sub.2, was obtained after subsequent calcination at 550 C. in air for 6 h.

Example 14

[0093] Chemical Vapor Deposition (CVD) The chemical vapor was formed by bubbling 100 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 45 mL of ethanol solution dissolving 40 g of SiCl.sub.4 and 42 mg of LiCl. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The Li doping silica catalyst, 1.1 wt. % LiSiO.sub.2, was obtained by subsequent quenching in silicone oil.

Example 15

[0094] Chemical Vapor Deposition (CVD) The chemical vapor was formed by bubbling 100 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 45 mL of ethanol solution dissolving 21 g of SiCl.sub.4 and 88 mg of NaCl. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The Na doping silica catalyst, 5.0 wt. % NaSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 16

Chemical Vapor Deposition (CVD)

[0095] The chemical vapor was formed by bubbling 100 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 32 mL of ethanol solution dissolving 22 g of SiCl.sub.4 and 108 mg of KCl. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The K doping silica catalyst, 7.5 wt. % KSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 17

[0096] Chemical vapor deposition (CVD)

[0097] The chemical vapor was formed by bubbling 120 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 66 mL of ethanol solution dissolving 19 g of SiCl.sub.4 and 10 mg of MgCl.sub.2. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 8 h. The Mg doping silica catalyst, 0.05 wt. % MgSiO.sub.2, was obtained by subsequent quenching in PAO.

Example 18

Chemical Vapor Deposition (CVD)

[0098] The chemical vapor was formed by bubbling 200 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 43 mL of ethanol solution dissolving 22 g of SiCl.sub.4 and 12 mg of AlCl.sub.3. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The Al doping silica catalyst, 0.01 wt. % AlSiO.sub.2, was obtained by subsequent quenching in cold water.

Example 19

Chemical Vapor Deposition (CVD)

[0099] The chemical vapor was formed by bubbling 110 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 59 mL of ethanol solution dissolving 24 g of SiCl.sub.4 and 8 mg of SrCl.sub.2. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 6 h. The Sr doping silica catalyst, 0.005 wt. % SrSiO.sub.2, was obtained by subsequent quenching in mineral oil.

Example 20

Chemical Vapor Deposition (CVD)

[0100] The chemical vapor was formed by bubbling 70 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 100 mL of ethanol solution dissolving 35 g of SiCl.sub.4 and 6 mg of BaCl.sub.2. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 8 h. The Ba doping silica catalyst, 0.002 wt. % BaSiO.sub.2, was obtained by subsequent quenching in PAO.

Example 21

Chemical Vapor Deposition (CVD)

[0101] The chemical vapor was formed by bubbling 300 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 100 mL of ethanol solution dissolving 44 g of SiCl.sub.4 and 3 mg of TiCl.sub.4. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 12 h. The Ti doping silica catalyst, 0.001 wt. % TiSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 22

Chemical Vapor Deposition (CVD)

[0102] The chemical vapor was formed by bubbling 130 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 90 mL of ethanol solution dissolving 44 g of SiCl.sub.4 and 120 mg of CeCl.sub.3. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 12 h. The Ce doping silica catalyst, 6.0 wt. % CeSiO.sub.2, was obtained by subsequent quenching in PAO.

Example 23

Chemical Vapor Deposition (CVD)

[0103] The chemical vapor was formed by bubbling 150 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 80 mL of ethanol solution dissolving 32 g of SiCl.sub.4 and 80 mg of MnCl.sub.2. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 7 h. The Mn doping silica catalyst, 1.2 wt. % MnSiO.sub.2, was obtained by subsequent quenching in cold water.

Example 24

Chemical Vapor Deposition (CVD)

[0104] The chemical vapor was formed by bubbling 90 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 55 g of SiCl.sub.4 and 120 mg of ZnCl.sub.2. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 12 h. The Zn doping silica catalyst, 3.6 wt. % Zn SiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 25

Chemical Vapor Deposition (CVD)

[0105] The chemical vapor was formed by bubbling 90 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 55 g of SiCl.sub.4 and 96 mg of (NH.sub.4).sub.2Mo.sub.2O.sub.7. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1600 C. in vacuum (10 Pa) for 10 h. The Mo doping silica catalyst, 2.2 wt. % MoSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 25

Chemical Vapor Deposition (CVD)

[0106] The chemical vapor was formed by bubbling 100 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 80 mL of ethanol solution dissolving 75 g of SiCl.sub.4 and 56 mg of CuCl.sub.2. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 7 h. The Cu doping silica catalyst, 5.2 wt. % CuSiO.sub.2, was obtained by subsequent quenching in cold water.

Example 26

Chemical Vapor Deposition (CVD)

[0107] The chemical vapor was formed by bubbling 120 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 180 mL of ethanol solution dissolving 66 g of SiCl.sub.4 and 90 mg of CrCl.sub.3. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 8 h. The Cr doping silica catalyst, 6.2 wt. % CrSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 27

Chemical Vapor Deposition (CVD)

[0108] The chemical vapor was formed by bubbling 230 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 18 g of SiCl.sub.4 and 10 mg of BiCl.sub.3. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1600 C. in vacuum (10 Pa) for 12 h. The Bi doping silica catalyst, 0.008 wt. % BiSiO.sub.2, was obtained by subsequent quenching in r PAO.

Example 28

Chemical Vapor Deposition (CVD)

[0109] The chemical vapor was formed by bubbling 220 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 100 mL of ethanol solution dissolving 80 g of SiCl.sub.4 and 120 mg of Sn Cl.sub.4. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 8 h. The Sn doping silica catalyst, 8 wt. % SnSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 29

Chemical Vapor Deposition (CVD)

[0110] The chemical vapor is formed by bubbling 170 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 80 mL of ethanol solution dissolving 69 g of SiCl.sub.4 and 80 mg of WCl.sub.6. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 10 h. The In doping silica catalyst, 5.6 wt. % WSiO.sub.2, was obtained by subsequent quenching in PAO.

Example 30

Vapor Phase Axial Deposition (VAD)

[0111] The vapor phase was formed by bubbling 500 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 180 mL of ethanol solution dissolving 189 g of SiCl.sub.4, 390 mg of Co.sub.2(CO).sub.8 and 400 mg Ni(CO).sub.4. The vapor was hydrolyzed and axial deposited on the surface of alumina support at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 6 h. The Co and Ni doping silica catalyst, 1.9 wt. % Co-2.5 wt. % NiSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 31

Vapor Phase Axial Deposition (VAD)

[0112] The vapor phase was formed by bubbling 550 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 300 mL of ethanol solution dissolving 101 g of SiCl.sub.4, 10 mg of AlCl.sub.3 and 500 mg of SnCl.sub.4. The vapor was hydrolyzed and axial deposited on the surface of alumina support at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 8 h. The Al and Sn doping silica catalyst, 0.005 wt. % Al-4.5 wt. % SnSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 32

Chemical Vapor Deposition (CVD)

[0113] The chemical vapor was formed by bubbling 200 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 80 g of SiCl.sub.4 and 100 mg of CeCl.sub.3 and 10 mg of FeCl.sub.3. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 12 h. The Ce and Fe doping silica catalyst, 6 wt. % Ce-0.001 wt. % FeSiO.sub.2, was obtained by subsequent quenching in PAO.

Example 33

Chemical Vapor Deposition (CVD)

[0114] The chemical vapor was formed by bubbling 250 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 80 mL of ethanol solution dissolving 42 g of SiCl.sub.4 and 80 mg of MnCl.sub.2 and 230 mg of (NH.sub.4).sub.2Mo.sub.2O.sub.7. The vapor was hydrolyzed and melted at 1200 C. The obtained doping material was melted at 1400 C. in vacuum (10 Pa) for 7 h. The Mn and Mo doping silica catalyst, 1.2 wt. % Mn-5.5 wt. % MoSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 34

Chemical Vapor Deposition (CVD)

[0115] The chemical vapor was formed by bubbling 90 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 55 g of SiCl.sub.4 and 120 mg of ZnCl.sub.2 and 16 mg of PbCl.sub.2. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 12 h. The Zn and Pb doping silica catalyst, 3.6 wt. % Zn-0.005 wt. % PbSiO.sub.2, was obtained by subsequent quenching in silicone oil.

Example 35

Chemical Vapor Deposition (CVD)

[0116] The chemical vapor was formed by bubbling 90 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 55 g of SiCl.sub.4 and 160 mg of BiCl.sub.3 and 22 mg of CuCl.sub.2. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1600 C. in vacuum (10 Pa) for 10 h. The Bi and Cu doping silica catalyst, 3.1 wt. % Bi-0.05 wt. % CuSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 36

Chemical Vapor Deposition (CVD)

[0117] The chemical vapor is formed by bubbling 180 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 90 mL of ethanol solution dissolving 40 g of SiCl.sub.4 and 220 mg of TiCl.sub.4 and 20 mg of NaCl. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 7 h. The Ti and Na doping silica catalyst, 5.2 wt. % Ti-0.02 wt. % NaSiO.sub.2, was obtained by subsequent quenching in cold water.

Example 37

Chemical Vapor Deposition (CVD)

[0118] The chemical vapor was formed by bubbling 200 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 66 g of SiCl.sub.4 and 10 mg of CaCl.sub.2 and 12 mg of LiCl. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 7 h. The Ca and Li doping silica catalyst, 0.15 wt. % Ca-0.028 wt. % LiSiO.sub.2, was obtained by subsequent quenching in silicone oil.

Example 38

Chemical Vapor Deposition (CVD)

[0119] The chemical vapor was formed by bubbling 400 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 360 mL of ethanol solution dissolving 100 g of SiCl.sub.4 and 400 mg of WCl.sub.6 and 222 mg of BaCl.sub.2. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1600 C. in vacuum (10 Pa) for 10 h. The Ba and W doping silica catalyst, 5.1 wt. % Ba-8 wt. % WSiO.sub.2, was obtained by subsequent quenching in rapeseed oil.

Example 39

Chemical Vapor Deposition (CVD)

[0120] The chemical vapor was formed by bubbling 200 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 120 mL of ethanol solution dissolving 65 g of SiCl.sub.4 and 50 mg of YCl.sub.3 and 60 mg of KCl. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 7 h. The Y and K doping silica catalyst, 0.08 wt. % Y-0.1 wt. % KSiO.sub.2, was obtained by subsequent quenching in cold water.

Example 40

Chemical Vapor Deposition (CVD)

[0121] The chemical vapor was formed by bubbling 400 mL/min of carrier gas (10 vol. % of H.sub.2 and 90 vol. % of He) into an 200 mL of ethanol solution dissolving 121 g of SiCl.sub.4 and 122 mg of C. Cl.sub.2 and 144 mg of FeCl.sub.3. The vapor was hydrolyzed and melted at 1300 C. The obtained doping material was melted at 1500 C. in vacuum (10 Pa) for 7 h. The Ti and Na doping silica catalyst, 1.2 wt. % Co-2.2 wt. % FeSiO.sub.2, was obtained by subsequent quenching in cold water.

2. Catalyst Characterization

[0122] a) XRD Characterization of 0.5 wt. % Ca-0.5 wt. % Fe SiO.sub.2 Catalyst

[0123] The XRD pattern of the catalyst indicates that there is only a broad diffraction peak at 23, which shows an amorphous characteristic peak of SiO.sub.2 (FIG. 1). Meanwhile, the diffraction peaks of Fe and Ca cannot be observed. All of these results are significantly different from the zeolite catalyst system.

[0124] b) Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) Leaching Characterization

[0125] The so-called ICP-AES acid leaching method is that the metal atoms on the surface the Si-based support can be dissolved in dilute nitric acid. The dilute nitric acid can only dissolves the metal, but it cannot dissolve the supports. Metal dopants confined in the Si-based support lattice or Si-based support cannot be dissolved. Meanwhile, the ICP-ASE results can obtain a degree of acid leaching (i.e., a ratio of surface loadings to surface loading and dopant loading). Firstly, the 0.5 wt. % Co@SiO.sub.2 catalyst was leached by dilute nitric acid, and the results showed that no Co atoms can be detected by ICP-AES, and further revealed the Co atoms have inserted the lattice of Si-based support. Subsequently, the 0.5 wt. % Co@SiO.sub.2 catalyst was leached by HF acid (the HF acid can dissolve either metal atoms or Si-based support), the results showed that all of Co atoms can be detected by ICP-AES, and the leaching amount is equal to the loading amount of the Co@SiO.sub.2 catalyst. The above results show that all of Co atoms have been inserted inside the lattice of Si-based support, and almost no Co atoms can be detected on the surface of Si-based support.

[0126] c) XPS Characterization of Fe-Doped 6H-SiC(0001)

[0127] As can be seen from the result of XPS Si2p (FIG. 2), there is an obvious shoulder peak at the binding energy of 99.6 eV, which attributes to the FeSi.sub.x species. Furthermore, the results show Fe atom could substitute the lattice C atoms, and then the Fe atoms could bond with Si atom to form the FeSi.sub.x species.

[0128] d) ICP-AES Leaching Characterization of 0.5 wt. % Co/SiO.sub.2 Catalyst

[0129] Firstly, the 0.5 wt. % Co@SiO.sub.2 catalyst was leached by dilute nitric acid, and the results showed that all of Co atoms can be detected by ICP-AES, and the leaching amount is equal to the catalyst loading amount. Furthermore, the results show that all of Co atoms have dispersed on the surface of Si-based support, and almost no Co atoms can be inserted inside the lattice of Si-based support.

[0130] e) High Resolution Transmission Microscopy (HR-TEM) Image of the Metal Lattice-Doping Catalyst

[0131] Furthermore, HR-TEM was used to characterize the dispersion and configuration of the metal lattice-doping catalyst prepared by the metal doping sol-gel method (Example 5 of catalyst preparation), FIG. 3. As can be seen from this image, we can observe a clear crystal structure (white circles), FIGS. 3A and 3B. The HR-TEM results prove that the so-called amorphous molten state catalysts exhibited the structure with long-range disorder and short-range order.

[0132] f) High Angle Annular Dark Field-Scanning Transmission Electron Microscope (HAADF-STEM) Image of the Single-Atom Metal Doping Catalyst

[0133] The HAADF-STEM was used to characterize the single-atom metal doping catalyst prepared by the metal doping CVD method (Example 2 of catalyst preparation), FIG. 4. As can be seen from this image, we can observe a lot of white dots (i.e. single-atom metal dopings). The HAADF-STEM results prove that the doping metals exhibited single-atom state.

3. Under the Oxygen-Free and Continuous Flow Conditions, Methane is Directly Converted to Olefin, Aromatics and Hydrogen.

[0134] All of the above catalyst prior to use need to be ground and sieved to 20-30 mesh as a backup. All of the following reaction examples are achieved in a continuous flow micro-reaction apparatus, which is equipped with gas mass flow meters, gas deoxy and dehydration units, and online product analysis chromatography. The tail gas of reaction apparatus is connected with the metering valve of chromatography, and thus periodic and real-time sampling and analysis will be achieved. The feed gas is composed of 10 vol. % N.sub.2 and 90 vol. % CH.sub.4 without specification, in which the nitrogen (N.sub.2) is used in an internal standard. To achieve the online product analysis, the Agilent 7890A chromatography with dual detector of FID and TCD is used. The FID detector with HP-1 capillary column is used to analyze the light olefin, light alkane and aromatics; and the TCD detector with Hayesep D packed column is used to analyze the light olefin, light alkane, methane, hydrogen and N.sub.2 internal standard. According to the carbon balance before and after reaction, methane conversion, product selectivity and coke deposition selectivity are calculated by the method from the two Chinese patents (CN1247103A, CN1532546A).

Example 1

[0135] The 0.75 g 0.5 wt. % CoSiO.sub.2 catalyst prepared by the Example 1 of catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 8.2% of methane conversion, 47.6% and 1.0 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 26.1% and 0.2 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 26.2% and 0.1 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, and 5.4 mol/g.sub.catalyst/s of f hydrogen generation rate.

Examples 2-7

[0136] The 0.75 g 0.5 wt. % CoSiO.sub.2 catalyst prepared by the Examples 2-7 of catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to the following temperatures (Table 1) at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted according to following values (Table 1). The results of methane conversion and products selectivity are as follows:

TABLE-US-00001 TABLE 1 Methane Ethylene Benzene Naphthalene Temp..sup.1 WHSV.sup.2 Conv..sup.3 Sel..sup.4 Sel. Sel. Example ( C.) (ml/g/h) (%) (%) (%) (%) 2 750 1600 2.5 70 16 14 3 850 2200 5.6 65 20 15 4 900 3600 6.4 55 22 23 5 950 5100 7.9 52 23 25 6 980 8400 15.2 48 24 28 7 1050 15200 9.8 46 25 29 .sup.1Temp. denotes temperature; .sup.2WHSV denotes the weight hourly space velocity; .sup.3Conv. denotes conversion; .sup.4Sel. Denotes selectivity.

Example 8

[0137] The 1.5 g 0.5 wt. % Ca-0.5 wt. % CoSiC catalyst prepared by Example 10 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 8.02% of methane conversion, 46.4% and 1.2 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 26.2% and 0.2 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 27.3% and 0.1 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, and 6.4 mol/g.sub.catalyst/s of hydrogen generation rate.

Examples 9-13

[0138] The 1.5 g 0.5 wt. % Ni-0.5 wt. % CoSiO.sub.2 catalyst prepared by Example 4 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to following temperatures (Table 1) at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to following value (Table 2). The results of methane conversion and products selectivity were as follows:

TABLE-US-00002 TABLE 2 Methane Ethylene Benzene Naphthalene Temp..sup.1 WHSV.sup.2 Conv..sup.3 Sel..sup.4 Sel. Sel. Example ( C.) (ml/g/h) (%) (%) (%) (%) 9 750 1600 2.2 68 16 16 10 850 2200 5.9 62 23 15 11 900 3600 6.8 51 24 25 12 950 5100 7.5 50 25 25 13 980 8400 14.3 49 23 28 .sup.1Temp. denotes temperature; .sup.2WHSV denotes the weight hourly space velocity; .sup.3Conv. denotes conversion; .sup.4Sel. Denotes selectivity.

Example 14

[0139] The 0.75 g 0.5 wt. % Ca-0.3 wt. % AlSiO.sub.2 catalyst prepared by Example 5 of catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. After 100 hours, the results were as follows: 7.8% of methane conversion, 46.8% and 0.9 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 27.2% and 0.2 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 25.8% and 0.1 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, and 5.2 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 15

[0140] The 0.75 g 0.5 wt. % CoSiOC.sub.0.5 catalyst prepared by Example 6 of catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 8.2% of methane conversion, 47.3% and 1.2 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 22.0% and 0.23 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 29.2% and 0.14 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, and 6.4 mol/g.sub.catalyst/s of hydrogen generation rate.

Examples 16-19

[0141] The 0.75 g 0.5 wt. % CoSiOC.sub.0.5 catalyst prepared by Example 6 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to following temperature (Table 1) at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to following value (Table 3). The results of methane conversion and products selectivity were as follows:

TABLE-US-00003 TABLE 3 Methane Ethylene Benzene Naphthalene Temp..sup.1 WHSV.sup.2 Conv..sup.3 Sel..sup.4 Sel. Sel. Example ( C.) (ml/g/h) (%) (%) (%) (%) 16 750 1600 3.0 72 12 16 17 850 2200 5.3 64 21 15 18 900 3600 7.1 53 24 23 19 950 5100 7.9 47 25 28 20 980 8400 15.5 45 23 32 .sup.1Temp. denotes temperature; .sup.2WHSV denotes the weight hourly space velocity; .sup.3Conv. denotes conversion; .sup.4Sel. Denotes selectivity.

Example 21

[0142] The 0.75 g 0.5 wt. % Ca-0.3 wt. % ZnSiOC.sub.0.5 catalyst prepared by Example 6 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 1000 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to 10000 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 31% of methane conversion, 52.1% and 5.7 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 21.3% and 0.8 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 26.4% and 0.6 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, and 28 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 22

[0143] The 0.75 g 0.5 wt. % Ca-0.3 wt. % CoSiOC.sub.0.5 catalyst prepared by the Example 9 of catalyst preparation method was loaded in the fix-bed reactor, and then purged with the Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas (10 vol. % CH.sub.4, 5 vol. % N.sub.2 and 85 vol. % He) was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 7.1% of methane conversion, 51.3% and 0.1 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 14.3% and 0.01 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 7.4% and 0.003 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, 26.6% of coke selectivity, and 0.5 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 23

[0144] The 0.75 g 0.5 wt. % Ca-0.6 wt. % CoSiOC.sub.0.5 catalyst prepared by the Example 6 of catalyst preparation method was loaded in the fix-bed reactor, and then purged with the Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas (88 vol. % CH.sub.4, 2 vol. % CO, 8 vol. % N.sub.2 and 2 vol. % He) was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 8.5% of methane conversion, 40.4% and 0.8 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 25.6% and 0.2 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 31.4% and 0.1 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, 0.4% of coke selectivity, and 5.5 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 24

[0145] The 0.75 g 0.2 wt. % Mg-0.3 wt. % ZnSiOC.sub.0.5 catalyst prepared by the Example 9 of catalyst preparation method was loaded in the fix-bed reactor, and then purged with the Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas (5.4 vol. % CH.sub.3OH, 85 vol. % CH.sub.4 and 9.6 vol. % N.sub.2) was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 6% of methane conversion, 64.5% and 0.9 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 15.1% and 0.07 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 8.9% and 0.02 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, 3.6% and 0.05 mol/g.sub.catalyst/s of ethane selectivity, 7.8% of coke selectivity, and 9.3 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 25

[0146] The 0.75 g 0.5 wt. % Ca-0.3 wt. % CoSiOC.sub.0.5 catalyst prepared by the Example 9 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged with the Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of the feed gas (5.4 vol. % CH.sub.3OH, 85 vol. % CH.sub.4 and 9.6 vol. % N.sub.2) was adjusted to 10000 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 22% of methane conversion, 60.9% and 6.6 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 14.3% and 0.5 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 7.6% and 0.2 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, 2.3% and 0.3 mol/g.sub.catalyst/s of ethane selectivity, 14.1% of coke selectivity, and 39 mol/g.sub.catalyst/s of f hydrogen generation rate.

Example 26

[0147] The 0.75 g 0.5 wt. % Mn-1.1 wt. % FeSiOC.sub.0.5 catalyst prepared by Example 6 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas (5 vol. % CO.sub.2, 85 vol. % CH.sub.4 and 10 vol. % N.sub.2) was adjusted to 4840 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 8.3% of methane conversion, 42.2% and 0.8 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 25.3% and 0.2 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 23.6% and 0.1 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, 3.2% and 0.06 mol/g.sub.catalyst/s of ethane selectivity, 7.1% of coke selectivity, and 2.0 mol/g.sub.catalyst/s of f hydrogen generation rate.

Example 27

[0148] The 0.5 g 0.2 wt. % K-0.6 wt. % FeSiO.sub.2 catalyst prepared by Example 5 of the catalyst preparation method (replacing Co(NO.sub.3).sub.2.6H.sub.2O and Ca(NO.sub.3).sub.2.4H.sub.2O with KNO.sub.3 and Fe(NO.sub.3).sub.3.9H.sub.2O) was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to 10800 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 9.8% of methane conversion, 43% of ethylene selectivity, 25% of benzene selectivity, 27% of Naphthalene selectivity, 2% of ethane selectivity, and 3% of coke selectivity.

Example 28

[0149] The 0.65 g 0.1 wt. % K-0.6 wt. % PbSiOC.sub.0.5 catalyst prepared by Example 6 of the catalyst preparation method (replacing Co(NO.sub.3).sub.2.6H.sub.2O and Ca(NO.sub.3).sub.2.4H.sub.2O with KNO.sub.3 and Pb(NO.sub.3).sub.2) was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to 10800 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 7.4% of methane conversion, 47% of ethylene selectivity, 23% of benzene selectivity, 28% of Naphthalene selectivity, and 2% of ethane selectivity.

Example 29

[0150] The 0.65 g 0.1 wt. % K-0.6 wt. % TiSiO.sub.2 catalyst prepared by Example 5 of the catalyst preparation method (replacing Co(NO.sub.3).sub.2.6H.sub.2O and Ca(NO.sub.3).sub.2.4H.sub.2O with KNO.sub.3 and tetrabutyl titanate) was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. Then the weight hourly space velocity (WHSV) of feed gas was adjusted to 10800 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 7.4% of methane conversion, 47% of ethylene selectivity, 23% of benzene selectivity, 28% of Naphthalene selectivity, and 2% of ethane selectivity.

Example 30

[0151] The 0.65 g 0.1 wt. % Mg-0.6 wt. % CeSiO.sub.2 catalyst prepared by Example 5 of the catalyst preparation method (replacing Co(NO.sub.3).sub.2.6H.sub.2O and Ca(NO.sub.3).sub.2.4H.sub.2O with Mg(NO.sub.3).2H.sub.2O and Ce(NO.sub.3).sub.3.6H.sub.2O) was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. Then the weight hourly space velocity (WHSV) of feed gas was adjusted to 10800 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 10.2% of methane conversion, 49% of ethylene selectivity, 23% of benzene selectivity, 25% of Naphthalene selectivity, 3% of ethane selectivity, and 3% of coke selectivity.

Example 31

[0152] The 0.65 g 0.1 wt. % Mg-0.3 wt. % SnSiO.sub.2 catalyst prepared by Example 5 of the catalyst preparation method (replacing Co(NO.sub.3).sub.2.6H.sub.2O and Ca(NO.sub.3).sub.2.4H.sub.2O with Mg(NO.sub.3).2H.sub.2O and SnCl.sub.4.5H.sub.2O) was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. Then the weight hourly space velocity (WHSV) of feed gas was adjusted to 11200 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 6.2% of methane conversion, 43% of ethylene selectivity, 24% of benzene selectivity, 28% of Naphthalene selectivity, 2% of ethane selectivity, and 3% of coke selectivity.

Example 32

[0153] The 0.75 g 0.5 wt. % FeSiC catalyst prepared by Example 5 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. Then the weight hourly space velocity (WHSV) of feed gas was adjusted to 15200 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 12.5% of methane conversion, 44% of ethylene selectivity, 22% of benzene selectivity, 24% of Naphthalene selectivity, 2% of ethane selectivity, 6% of coke selectivity, and 7.0 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 33

[0154] The 0.75 g 0.8 wt. % Ca-1.1 wt. % FeSiOC.sub.0.5 catalyst prepared by Example 9 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas (5.0 vol. % H.sub.2O, 85.5 vol. % CH.sub.4 and 9.5 vol. % N.sub.2) was adjusted to 10000 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 12.1% of methane conversion, 34.7% and 1.2 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 25.6% and 0.3 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 25.1% and 0.2 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, 2.4% and 0.08 mol/g.sub.catalyst/s of ethane selectivity, 5.3% of CO selectivity, and 12 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 34

[0155] The 0.75 g 0.5 wt. % Ca-0.5 wt. % CoSi.sub.3N.sub.4 catalyst prepared by Example 11 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor is programmed from room temperature up to 950 C. at a heating rate of 10 C./min. Then the weight hourly space velocity (WHSV) of feed gas (90 vol. % CH.sub.4 and 10 vol. % N.sub.2) was adjusted to 5000 ml/g/h. After the WHSV being kept 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 14% of methane conversion, 40.1% and 1.3 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 22.3% and 0.3 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 26.2% and 0.2 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, 11.4% of coke selectivity, and 8 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 35

[0156] The 0.75 g 0.5 wt. % CoSiOC.sub.0.35N.sub.0.2 catalyst prepared by Example 12 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas (90 vol. % CH.sub.4 and 10 vol. % N.sub.2) was adjusted to 4840 ml/g/h. After the WHSV being kept for 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 16.2% of methane conversion, 46% and 1.4 mol/g.sub.catalyst/s of ethylene selectivity and ethylene generation rate, 27.5% and 0.35 mol/g.sub.catalyst/s of benzene selectivity and benzene generation rate, 26.5% and 0.3 mol/g.sub.catalyst/s of Naphthalene selectivity and Naphthalene generation rate, and 8 mol/g.sub.catalyst/s of hydrogen generation rate.

Example 36

[0157] The 0.75 g 0.5 wt. % Co/SiO.sub.2 catalyst prepared by Example 13 of the catalyst preparation method was loaded in the fix-bed reactor, and then purged by Ar gas (25 ml/min) for 20 mins. Maintaining a constant flow rate of Ar, the reactor was programmed from room temperature up to 950 C. at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of the feed gas (90 vol. % CH.sub.4 and 10 vol. % N.sub.2) was adjusted to 4840 ml/g/h. After the WHSV being kept for 20 mins, the reaction results were analyzed by the online chromatography. The results were as follows: 18.5% of methane conversion, <3% of ethylene selectivity, <1% of benzene selectivity and Naphthalene selectivity, and >96% of coke selectivity.

[0158] In summary, under the conditions encountered in a fixed bed reactor (i.e. reaction temperature: 750-1200 C.; reaction pressure: atmospheric pressure; the weight hourly space velocity of feed gas: 1000-30000 ml/g/h; and fixed bed), conversion of methane is 8-50%. The selectivity of olefins is 30-90%. And selectivity of aromatics is 10-70%. There is no coking. The reaction process has many advantages, including a long catalyst life (>100 hrs), high stability of redox and hydrothermal properties under high temperature, high selectivity towards target products, zero coke deposition, easy separation of products, good reproducibility, safe and reliable operation, etc., all of which are very desirable for industrial application.

Examples 37-42

[0159] The 1.2 wt. % Mn-5.5 wt. % MoSiO.sub.2 catalyst prepared by the Examples 14-29, 32-40 of catalyst preparation method was loaded in the fix-bed reactor, and then flushed with the Ar gas (25 ml/min) for 20 mins. To remain a constant flow rate of Ar, the reactor is programmed from room temperature up to following temperature (Table 1) at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to following value (Table 4). The results of methane conversion and products selectivity were as follows:

TABLE-US-00004 TABLE 4 Methane Ethylene Benzene Naphthalene Temp..sup.1 WHSV.sup.2 Conv..sup.3 Sel..sup.4 Sel. Sel. Example ( C.) (ml/g/h) (%) (%) (%) (%) 37 750 1900 1.5 88 12 0 38 850 2800 3.6 80 18 2 39 900 4000 4.4 78 16 6 40 950 9000 6.9 75 28 7 41 980 15000 7.2 62 29 9 42 1050 25200 8.8 60 30 10 .sup.1Temp. denotes temperature; .sup.2WHSV denotes the weight hourly space velocity; .sup.3Conv. denotes conversion; .sup.4Sel. Denotes selectivity.

Examples 43-48

[0160] The 1.9 wt. % Co-2.5 wt. % NiSiO.sub.2 catalyst prepared by the Examples 30 and 31 of catalyst preparation method was loaded in the fix-bed reactor, and then flushed with the Ar gas (25 ml/min) for 20 mins. To remain a constant flow rate of Ar, the reactor is programmed from room temperature up to following temperature (Table 1) at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to following value (Table 5). The results of methane conversion and products selectivity were as follows:

TABLE-US-00005 TABLE 5 Methane Ethylene Benzene Naphthalene Temp..sup.1 WHSV.sup.2 Conv..sup.3 Sel..sup.4 Sel. Sel. Example ( C.) (ml/g/h) (%) (%) (%) (%) 43 950 5000 6.2 55 30 15 44 1000 12000 16 49 31 20 45 1050 4000 24 51 30 19 46 1100 9000 27 48 28 24 47 1150 15000 34 45 30 25 48 1200 25200 38 44 30 26 .sup.1Temp. denotes temperature; .sup.2WHSV denotes the weight hourly space velocity; .sup.3Conv. denotes conversion; .sup.4Sel. Denotes selectivity.

Examples 49-54

[0161] The 0.005 wt. % SrSiO.sub.2 catalyst prepared by the Examples 14-29, 32-40 of catalyst preparation method was loaded in the fix-bed reactor, and then flushed with the Ar gas (25 ml/min) for 20 mins. To remain a constant flow rate of Ar, the reactor is programmed from room temperature up to following temperature (Table 1) at a heating rate of 10 C./min. And then the weight hourly space velocity (WHSV) of feed gas was adjusted to following value (Table 6). The results of methane conversion and products selectivity were as follows:

TABLE-US-00006 TABLE 6 Methane Ethylene Benzene Naphthalene Temp..sup.1 WHSV.sup.2 Conv..sup.3 Sel..sup.4 Sel. Sel. Example ( C.) (ml/g/h) (%) (%) (%) (%) 49 950 5000 5.2 52 32 15 50 1000 12000 14 45 33 22 51 1050 4000 21 48 31 21 52 1100 9000 23 45 29 26 53 1150 15000 27 42 32 26 54 1200 25200 30 38 30 32 .sup.1Temp. denotes temperature; .sup.2WHSV denotes the weight hourly space velocity; .sup.3Conv. denotes conversion; .sup.4Sel. denotes selectivity.