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US-20260125714-A1 - METHANE CONVERSION SYSTEM AND METHODS THEREOF

US20260125714A1US 20260125714 A1US20260125714 A1US 20260125714A1US-20260125714-A1

Abstract

A method for methane oxidation by methanotrophic bacteria to reduce methane emissions may include: conveying a gas comprising methane to a methane conversion system that comprises a bed of oxic soil containing methanotrophic bacteria; contacting the methanotrophic bacteria and the gas; and allowing the methanotrophic bacteria to oxidize at least a portion of the methane to carbon dioxide. The gas stream may have about about 100 ppm to about 10,000 ppm methane present.

Inventors

  • Lin Zhao
  • Sam AMINFARD
  • Jordan C. ANGLE

Assignees

  • ExxonMobil Technology and Engineering Company

Dates

Publication Date
20260507
Application Date
20230929

Claims (19)

  1. 1 . A method comprising: conveying a gas comprising methane to a methane conversion system that comprises an oxic soil containing methanotrophic bacteria, wherein methane is present in the gas stream at about 100 ppm to about 10,000 ppm; contacting the methanotrophic bacteria and the gas; and allowing the methanotrophic bacteria to oxidize at least a portion of the methane to carbon dioxide.
  2. 2 . The method of claim 1 , wherein the carbon dioxide is vented to the atmosphere.
  3. 3 . The method of claim 1 , wherein the gas stream originates from a lean-burn reciprocating engine.
  4. 4 . The method of claim 3 , wherein the lean-burn reciprocating engine is capable of about 500 hp to about 5000 hp.
  5. 5 . The method of claim 1 , wherein the methanotrophic bacteria comprise Methylomonas aurantiaca , Methylomonas fodinarum , Methylomonas methanica , Methylobacter albus , Methylobacter marinus , Methylobacter whittenburyi , Methylococcus capsulatus , Methylococcus thermophiles, Methylomicrobium agile , Methylomicrobium album , Methylomicrobium pelagicum , or any combination thereof.
  6. 6 . The method of claim 1 , wherein the methanotrophic bacteria are native microbes of the oxic soil.
  7. 7 . The method of claim 1 , wherein the methane conversion system further comprises a containment structure for the bed.
  8. 8 . The method of claim 1 , wherein the bed has a bed depth of about 20 cm deep to about 50 cm deep.
  9. 9 . The method of claim 1 , wherein the methane conversion system comprises a gas diffuser configured to distribute the gas stream through the oxic soil.
  10. 10 . The method of claim 1 , wherein the methane conversion system further comprises an underground vessel in which the gas stream is passed through and/or stored before contact with the methanotrophic bacteria.
  11. 11 . The method of claim 1 , wherein the methanotrophic bacteria have a methane conversion capacity of about 0.01% to about 10% based on the ratio of the volume of methane to the volume of the oxic soil in which the methanotrophic bacteria are located.
  12. 12 . The method of claim 1 , wherein the methanotrophic bacteria co-oxidize tetrachloromethane, trichloromethane, dichloromethane, trichloroethylene, vinyl chloride, benzene, toluene, methanol, or any combination thereof.
  13. 13 . The method of claim 1 , wherein the methane oxidation occurs at about 20° C. to about 45° C.
  14. 14 . A methane conversion system comprising: a source that produces a gas stream having a methane concentration from about 100 ppm to about 10,000 ppm; oxic soil containing methanotrophic bacteria, wherein the methanotrophic bacteria are capable of oxidizing at least a portion of the methane to carbon dioxide; and a gas distribution system configured to receive the gas stream and distribute the gas stream through the oxic soil.
  15. 15 . The methane conversion system of claim 14 , wherein the source is a lean-burn reciprocating engine.
  16. 16 . The methane conversion system of claim 14 , wherein the methanotrophic bacteria comprise Methylomonas aurantiaca , Methylomonas fodinarum , Methylomonas methanica , Methylobacter albus , Methylobacter marinus , Methylobacter whittenburyi , Methylococcus capsulatus , Methylococcus thermophiles , Methylomicrobium agile , Methylomicrobium album , Methylomicrobium pelagicum , or any combination thereof.
  17. 17 . The methane conversion system of claim 14 , further comprising a containment structure for the bed.
  18. 18 . The methane conversion system of claim 14 , wherein the bed has a bed depth of about 20 cm deep to about 50 cm deep.
  19. 19 . The methane conversion system of claim 14 , further comprising an underground vessel in which the gas stream is passed through and/or stored, wherein the underground vessel is downstream of the source and upstream of the gas distribution system.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Application Ser. No. 63/379,333, entitled “METHANE CONVERSION SYSTEM AND METHODS THEREOF,” filed Oct. 13, 2022, the disclosure of which is hereby incorporated by reference in its entirety. FIELD OF INVENTION The present disclosure relates to methane oxidation, and more particularly, methane oxidation by methanotrophic bacteria to reduce methane emissions. BACKGROUND Methane is the second most abundant anthropogenic greenhouse gas after carbon dioxide, accounting for approximately 20% of global emissions. Although less abundant, methane is significantly more potent than carbon dioxide in terms of global warming potential because methane is estimated to be more than 25 times as effective as carbon dioxide at trapping heat in the atmosphere on a 100-year basis. Over the last two centuries, methane concentrations in the atmosphere have more than doubled, largely due to human-related activities, such as landfill use, oil and gas production and processing, agricultural activities, coal mining, stationary and mobile combustion, wastewater treatment, and other industrial processes. Because methane is a powerful greenhouse gas, a reduction in methane emissions would have a rapid and significant effect on the atmospheric warming potential. Several methods to reduce methane emissions have been suggested, the simplest method being a reduction or elimination of the processes that use or produce methane. However, reducing or eliminating processes producing or utilizing methane is often infeasible and costly. In situations where the use or production of methane is necessary, other methods of methane mitigation, such as the conversion of methane into less environmentally-harmful species, are utilized. There are various techniques to convert methane including (i) reforming to produce syngas, including steam reforming, dry reforming, and partial oxidation; (ii) oxidative coupling; and (iii) conversion to oxygenates such as methanol. However, the metal catalysts commonly used in these techniques can be costly to produce and use, making these processes economically unattractive and creating a gap in the demand for methane emission control. SUMMARY OF INVENTION A nonlimiting example method of the present disclosure may comprise: conveying a gas comprising methane to a methane conversion system that comprises a bed of oxic soil containing methanotrophic bacteria; wherein methane is present in the gas stream at about 100 ppm to about 10,000 ppm; contacting the methanotrophic bacteria and the gas; and allowing the methanotrophic bacteria to oxidize at least a portion of the methane to carbon dioxide. A nonlimiting example methane conversion system of the present disclosure may comprise: a source that produces a gas stream having a methane concentration from about 100 ppm to about 10,000 ppm; oxic soil containing methanotrophic bacteria, wherein the methanotrophic bacteria are capable of oxidizing at least a portion of the methane to carbon dioxide; and a gas distribution system configured to receive the gas stream and distribute the gas stream through the oxic soil. These and other features and attributes of the disclosed methods and systems of the present disclosure and their advantageous applications and/or uses will be apparent from the detailed description which follows. BRIEF DESCRIPTION OF THE DRAWINGS To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings. The following figures are included to illustrate certain aspects of the disclosure, and should not be viewed as exclusive configurations. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure. FIG. 1 illustrates an example of a methane conversion system of the present disclosure. FIG. 2 illustrates another example of a methane conversion system of the present disclosure. DETAILED DESCRIPTION The present disclosure relates to methane oxidation, and more particularly, methane oxidation by methanotrophic bacteria to reduce methane emissions. Methanotrophic bacteria—microorganisms that metabolize methane gas—are ubiquitous in nature, where the bacteria utilize oxygen and water to oxidize methane. This process has been shown to play an essential role in landfill methane oxidation, oxidizing up to 100% of the methane entering shallow, cap-layer soils. Methanotrophs can live under aerobic or anaerobic conditions. Aerobic methanotrophs combine oxygen and methane to form carbon dioxide and formaldehyde, the latter being incorporated into organic compounds via the serine pathway or the ribulose monophosphate pathway. Conversely, anaerobic methanotrophs use electron acceptors other than oxygen for methane oxidation. In one form of the pres