Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Reexamination Certificate
2000-07-14
2001-07-31
Wong, Edna (Department: 1741)
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
Reexamination Certificate
active
06267849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for converting methane hydrates to methanol and hydrogen through exposure to light. More specifically, the invention relates to converting methane stored in natural gas hydrates to methanol by the reaction of light.
2. Background of the Invention
Methane hydrates represent a large natural reserve of methane, and have an energy potential equal to more than twice that of all other fossil fuels combined. They are environmentally advantageous in that methane from hydrates produces less carbon dioxide than other forms of fossil fuels. Wide production could reduce carbon dioxide emissions by as much as twenty percent worldwide.
Methane hydrates are found in deep ocean sediments and Arctic permafrost as pressurized and frozen, icelike deposits: a frozen mixture of methane contained within an ice-water mix. The reserves contain methane in a highly concentrated form, but the methane is difficult to extract and obtain. The U.S. Geological Survey has estimated the value of gas hydrates in the United States at 320,000 trillion cubic feet of gas, about 200 times the amount of conventional natural gas resources and reserves in the country.
The commercial extraction of methane hydrate is technologically difficult. To produce the methane contained in these hydrates, the hydrate must be thawed or the over pressure must be released. Either of these steps will release the methane from its natural deposit. However, how to collect and distribute the methane becomes problematic. Since the majority of the known hydrate deposits are not located near the natural gas transportation infrastructure, the methane must be compressed and shipped under pressure, or new pipelines need to be constructed.
In addition, current exploration techniques use to locate hydrate zones, such as sonar, are relatively crude, involving interpretative guess work.
Conversion of the methane while it is still contained in the hydrate avoids these problems.
U.S. Pat. No. 5,720,858, owned by the applicant herein, describes a method for converting methane and water into methanol and hydrogen using visible light and a catalyst. The conversion of methane disclosed by the '858 patent requires heating of methane saturated water to temperatures greater than 70° C.
There is thus a need for a method for producing methanol from methane hydrates, particularly a process that allows for the direct conversion of methane contained within the hydrate in situ.
SUMMARY OF THE INVENTION
The present invention discloses a method for converting methane hydrates to methanol, as well as hydrogen, through exposure to light. The process includes conversion of methane hydrates by light where a radical initiator has been added, and may be modified to include the conversion of methane hydrates with light where a photocatalyst (such as oxide salts of tungsten, titanium, or zirconium) doped by a suitable metal (such as copper, lanthanum, platinum, or lithium) and an electron transfer agent to produce methanol and hydrogen. The present invention operates at temperatures below 0° C., and allows for the direct conversion of methane contained within the hydrate in situ. The hydrate does not need to be harvested or the methane contained within the hydrate released for the conversion to occur.
REFERENCES:
patent: 5720858 (1998-02-01), Noceti et al.
Bockrath Bradley C.
Noceti Richard P.
Taylor Charles E.
Caress Virginia B.
Dvorscak Mark P.
Fisher Robert J.
The United States of America as represented by the United States
Wong Edna
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