Noble metal catalysts and processes for reforming of methane and other hydrocarbons

Patent metadata

Field	Value
Publication number	US-10906808-B2
Application number	US-201715813781-A
Country	US
Kind code	B2
Filing date	Nov 15, 2017
Priority date	Nov 15, 2017
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

Processes for converting methane and/or other hydrocarbons to synthesis gas (i.e., a gaseous mixture comprising H2 and CO) are disclosed, in which at least a portion of the hydrocarbon(s) is reacted with CO2. At least a second portion of the methane may be reacted with H2O (steam), thereby improving overall thermodynamics of the process, in terms of reducing endothermicity (ΔH) and the required energy input, compared to “pure” dry reforming in which no H2O is present. Catalysts for such processes advantageously possess high activity and thereby can achieve significant levels of methane conversion at temperatures below those used conventionally under comparable conditions. These catalysts also exhibit high sulfur tolerance, in addition to reduced rates of carbon (coke) formation, even in the processing (reforming) of heavier (e.g., naphtha boiling-range or jet fuel boiling-range) hydrocarbons. The robustness of the catalyst translates to high operating stability. A representative catalyst comprises 1 wt-% Pt and 1 wt-% Rh as noble metals, on a cerium oxide support.

First claim

The invention claimed is:

1. A process for producing a synthesis gas product, the process comprising feeding a gaseous mixture comprising methane, CO 2 , and H 2 O to a CO 2 -steam reforming reactor, said CO 2 -steam reforming reactor containing a catalyst comprising at least two noble metals selected from the group consisting of Pt, Rh, Ru, Pd, Ag, Os, Ir, and Au on a solid support comprising cerium oxide in an amount of at least 80% by weight of the solid support, said catalyst comprising less than 0.05% by weight of metals other than said at least two noble metals and metals of said solid support,
wherein, in the CO 2 -steam reforming reactor, at least about 80% of the methane is converted by reaction with CO 2 and H 2 O as oxidants.

2. The process of claim 1 , wherein the at least two noble metals are Pt and Rh.

3. The process of claim 2 , wherein the Pt is present in an amount from about 0.05% to about 5% by weight of the catalyst.

4. The process of claim 2 , wherein the Rh is present in an amount from about 0.05% to about 5% by weight of the catalyst.

5. The process of claim 4 , wherein the Rh is present in the catalyst in an amount from about 0.5% to about 2% by weight.

6. The process of claim 3 , wherein the Pt is present in the catalyst in an amount from about 0.5% to about 2% by weight.

7. The process of claim 1 , wherein the H 2 O is present in the gaseous mixture in an amount from about 15 mol-% to about 70 mol-%.

8. The process of claim 1 , further comprising, prior to said feeding of the gaseous mixture comprising methane, CO 2 , and H 2 O to the CO 2 -steam reforming reactor:
combining a methane-containing feedstock and a CO 2 -containing oxidant to obtain the gaseous mixture,
wherein the H 2 O in the gaseous mixture is initially present in the methane-containing feedstock and/or the CO 2 -containing oxidant.

9. The process of claim 8 , wherein the gaseous mixture further comprises at least about 100 mol-ppm of total sulfur.

10. The process of claim 8 , wherein the gaseous mixture further comprises aromatic and olefinic hydrocarbons in a combined amount from about 1 mol-% to about 25 mol-%.

11. The process of claim 8 , wherein the methane-containing feedstock comprises natural gas or methane from a renewable methane source.

12. The process of claim 1 , further comprising, prior to said feeding of the gaseous mixture comprising methane, CO 2 , and H 2 O to the CO 2 -steam reforming reactor:
combining an H 2 O-containing oxidant, a methane-containing feedstock, and a CO 2 -containing oxidant to obtain the gaseous mixture.

13. The process of claim 1 , wherein conditions of the CO 2 -steam reforming reactor include a weight hourly space velocity (WHSV) from about 0.1 −1 to about 2.5 hr −1 , to provide the synthesis gas product as an effluent from the CO 2 -steam reforming reactor.

14. The process of claim 1 , wherein conditions of the CO 2 -steam reforming reactor include a temperature from about 649° C. to about 816° C.

15. The process of claim 14 , wherein the conditions further include a gauge pressure from about 0 kPa to about 517 kPa.

16. The process of claim 1 , wherein, in the CO 2 -steam reforming reactor, at least about 85% of the methane is converted at a temperature of at most about 704° C.

17. The process of claim 1 , wherein the synthesis gas product comprises H 2 in an amount representing at least about 70% of hydrogen in hydrogen-containing compounds, including the methane and the H 2 O present in the gaseous mixture.

18. The process of claim 1 , wherein the synthesis gas product has a molar H 2 :CO ratio from about 1.5:1 to about 2.3:1.

19. The process of claim 1 , wherein the gaseous mixture further comprises one or more light hydrocarbons selected from the group consisting of ethane, ethylene, propane, and propylene.

20. The process of claim 1 , wherein the methane is obtained from a renewable resource.

21. The process of claim 20 , wherein the renewable resource is biomass.

22. A process for producing a synthesis gas product, the process comprising feeding a gaseous mixture comprising methane, CO 2 , and H 2 O to a CO 2 -steam reforming reactor, said CO 2 -steam reforming reactor containing a catalyst comprising from about 0.3 wt-% to about 3 wt-% Pt and from about 0.3 wt-% to about 3 wt-% Rh on a solid support comprising cerium oxide in an amount of at least 80% by weight of the solid support,
wherein reforming conditions of the CO 2 -steam reforming reactor include a weight hourly space velocity (WHSV) from about 0.1 −1 to about 4.0 −1 and a gauge pressure from about 0 kPa to about 517 kPa, and
wherein the catalyst is sufficiently active to achieve, in the CO 2 -steam reforming reactor, a conversion of the methane of at least 95% by reaction with CO 2 and H 2 O as oxidants at a temperature of 760° C.

23. A process for producing a synthesis gas product, the process comprising feeding a gaseous mixture comprising methane, CO 2 , and H 2 O to a CO 2 -steam reforming reactor, said CO 2 -steam reforming reactor containing a catalyst comprising at least one noble metal on a solid support comprising cerium oxide in an amount of at least 80% by weight of the solid support,
wherein, in the CO 2 -steam reforming reactor, at least about 80% of the methane is converted by reaction with CO 2 and H 2 O as oxidants, and
wherein the gaseous mixture has a sulfur level from about 10 mol-ppm to about 1 mol-%, the process further comprising adjusting a temperature of the CO 2 -steam reforming reactor based on a determination of said sulfur level.

24. The process of claim 23 , wherein the sulfur level is from about 100 mol-ppm to about 1000 mol-ppm.

25. The process of claim 24 , wherein the sulfur level is from about 500 mol-ppm to about 1000 mol-ppm.

Assignees

• Gas Technology Inst

Inventors

• Marker Terry
• Linck Martin
• Wangerow Jim
• Ortiz-Toral Pedro

Classifications

• C01B2203/0405

  Purification by membrane separation · CPC title

• C01B2203/043

  Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration · CPC title

• C01B2203/0283

  containing a CO-shift step, i.e. a water gas shift step · CPC title

• B01J23/63

  with rare earths or actinides · CPC title

• C01B2203/1064

  Platinum group metal catalysts · CPC title