Method and Apparatus for Hydrogen Production from Greenhouse Gas Saturated Carbon Nanotubes and Synthesis of Carbon Nanostructures Therefrom Page: 6
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US 7,468,097 B2
METHOD AND APPARATUS FOR
HYDROGEN PRODUCTION FROM
GREENHOUSE GAS SATURATED CARBON
NANOTUBES AND SYNTHESIS OF CARBON
This application claims priority to U.S. Provisional Patent
Application Ser. No. 60/591,481, entitled "Process andAppa-
ratus for the Storage and Removal of Hydrocarbon and
Greenhouse Gas Species from Carbon Nanotubes and the
Nanosynthesis of Carbon Nanotubes Therefrom," filed on
Jul. 27, 2004, having Henley, et al., listed as the inventors, the
entire content of which is hereby incorporated by reference.
STATEMENT OF RIGHTS TO INVENTIONS
MADE UNDER FEDERALLY SPONSORED
No federal grants or funds were used in the development of
the present invention.
This invention is generally related to an apparatus and
method of capturing, and storing hydrocarbon gas and green-
house gas species within a carbon nanotube matrix. Addition-
ally, methods are directed to the production of hydrogen
without a substantial carbon dioxide byproduct. More spe-
cifically, this invention is related to a method that utilizes an
initial amount of carbon nanotubes as a substrate to capture a
hydrocarbon gas and/or a greenhouse gas, forming nanotubes
saturated with a hydrocarbon gas or a greenhouse gas, or both.
The nanotubes saturated with hydrocarbon gas or greenhouse
gas can then be placed under a vacuum and exposed to micro-
wave energy generating: (a) a release of hydrogen into a
storage vessel; and (b) de novo synthesis of carbon nanotubes
from the recycled carbon elements of the hydrocarbon gas or
the greenhouse gas. The newly synthesized carbon nano-
tubes, in turn, become saturated with hydrocarbon gas or
greenhouse gas, which can be exposed to microwave radia-
tion and produce even more newly synthesized carbon nano-
tubes. This process represents an apparatus and method of
making hydrogen with an industrial valuable byproduct, car-
bon nanotubes. Additionally, the process is substantially free
from carbon contaminants and carbon dioxide production.
Hydrocarbon and Greenhouse Gas Production. Many
chemical compounds found in the Earth's atmosphere act as
"greenhouse gases." These gases allow sunlight to enter the
atmosphere freely. When sunlight strikes the Earth's surface,
some of it is reflected back towards space as infrared radiation
(heat). Greenhouse gases absorb this infrared radiation and
trap the heat in the atmosphere. Over time, the amount of
energy sent from the sun to the Earth's surface should be
about the same as the amount of energy radiated back into
space, leaving the temperature of the Earth's surface roughly
constant. However, there is growing concern in the scientific
community that greenhouse gases are accumulating in
Earth's atmosphere as a result of human activities, causing
surface air temperatures and sub-surface ocean temperatures
to rise. The concern that increases in global temperature over
the past few decades are due to human activities directly.
Additionally, increases in global temperatures have prompted
international governments to monitor and/or reduce the
amount of greenhouse gas emissions that are produced by
Many gases exhibit "greenhouse" properties. Some of
them occur in nature (e.g. water vapor, carbon dioxide, meth-
ane, and nitrous oxide), while others are exclusively human-
generated (e.g. gases used for aerosols, HFCs, PFCs and SF6).
5 Most of the human-generated greenhouse gas emissions of
carbon dioxide produced in the United States are a result of
energy production, more specifically, energy-related usage of
petroleum and natural gas. Another greenhouse gas emission,
methane, comes from landfills, coal mines, oil and gas opera-
10 tions, and agriculture. Nitrous oxide is also emitted from
burning fossil fuels and through the use of certain fertilizers
and industrial processes.
Hydrogen Energy Production. There is a currently a need
for hydrogen to play a greater role in the energy market
15 because of the increasing demand for fuel cell systems and the
growing demand for reduction of greenhouse gases and zero-
emission fuels. Hydrogen production must keep pace with
this growing market demand, but there are still some technical
and infrastructure hurdles that first need to be overcome.
20 Although hydrogen is the most abundant element on the
planet, it is bound to other elements from which it must be
separated before it can be used in energy production or as a
chemical feedstock, etc. Thermo-chemical and electrochemi-
cal methods for hydrogen generation have been developed,
25 however these processes are generally costly, energy-inten-
sive, produce carbon dioxide, and not always environmen-
tally friendly. Thus, hydrogen production in the United States
is not generally used for energy production. For example,
approximately 95% of the hydrogen produced in the United
30 States today comes from carbonaceous raw materials, prima-
rily fossil in its origin. However, only a fraction of the hydro-
gen produced is currently employed for energy purposes. The
bulk of this hydrogen is used as chemical feedstock for pet-
rochemical, food, electronics and metallurgical industries.
35 In the future, increased hydrogen production will most
likely be met by conventional technologies, such as natural
gas reformation. In these processes, hydrogen is produced
and the carbon is converted to carbon dioxide and released to
the atmosphere. With the growing concern of global climate
40 change, alternatives to the atmospheric release of carbon
dioxide are needed. Sequestration of carbon dioxide is an
option but it is also energy intensive and expensive. Better
methods of hydrogen production are needed, including envi-
ronmentally friendly methods that do not produce carbon
Reducing the demand for fossil resources remains a sig-
nificant concern for most industrialized nations. Renewable
resource based processes including solar or wind driven elec-
trolysis and photolytic water splitting hold promise for clean
50 hydrogen production. Such processes are desirable but con-
siderable advance must be made before these processes are
technologically feasible and economically competitive.
Carbon Nanotubes Science and Technology. Nanotechnol-
ogy is based on a principle of building functional structures
55 with chemistry andbiology one atom at a time. The first report
of a nanostructure was the Buckminsterfullerene, which is
essentially a series of very large carbon molecules, the most
common form of which is the C6o molecule. Carbon nano-
tubes were discovered in 1991 and consist of fullerene-related
60 structures ofgraphene cylinders closed at either end with caps
containing pentagonal rings. Carbon nanotubes are a special
class of what is widely referred to as nanostructure or a
man-made structure in the physical size range of 1 to 100
nanometers ("nm"). Bulk quantities of hollow carbon nano-
65 tubes can be produced using an arc-evaporation technique.
The experimental variables for producing nanotubes include:
ambient pressure, electrode size, gap size, power, and flux
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Henley, Donald E. & Imholt, Timothy. Method and Apparatus for Hydrogen Production from Greenhouse Gas Saturated Carbon Nanotubes and Synthesis of Carbon Nanostructures Therefrom, patent, December 23, 2008; [Washington, D.C.]. (https://digital.library.unt.edu/ark:/67531/metadc305434/m1/6/: accessed July 25, 2021), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT College of Arts and Sciences.