U.S. patent application number 10/946464 was filed with the patent office on 2006-03-23 for hollow porous-wall glass microspheres for hydrogen storage.
Invention is credited to Leung K. Heung, Ray F. Schumacher, George G. Wicks.
Application Number | 20060060820 10/946464 |
Document ID | / |
Family ID | 36072463 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060060820 |
Kind Code |
A1 |
Schumacher; Ray F. ; et
al. |
March 23, 2006 |
Hollow porous-wall glass microspheres for hydrogen storage
Abstract
A hollow glass microsphere is provided having a diameter range
of between 1 to 140 microns, a density of between 0.05 to 0.50
gm/cc, a porous-wall structure having wall openings defining an
average pore size of between 10 to 1000 angstroms, and which
contains therein a hydrogen storage material. The porous-wall
structure facilitates the introduction of a hydrogen storage
material into the interior of the hollow glass microsphere.
Thereafter, a barrier coating may be applied and/or the
microspheres are processed to alter or reduce the effective pore
size. In this manner, the hollow glass microsphere can provide a
membrane for the selective transport of hydrogen through the porous
walls of the microsphere, the small pore size preventing gaseous or
liquid contaminants from entering the interior of the hollow glass
microsphere.
Inventors: |
Schumacher; Ray F.; (Aiken,
SC) ; Wicks; George G.; (Aiken, SC) ; Heung;
Leung K.; (Aiken, SC) |
Correspondence
Address: |
J. BENNETT MULLINAX, LLC
P. O. BOX 26029
GREENVILLE
SC
29616-1029
US
|
Family ID: |
36072463 |
Appl. No.: |
10/946464 |
Filed: |
September 21, 2004 |
Current U.S.
Class: |
252/188.25 |
Current CPC
Class: |
C01B 3/0084 20130101;
B01D 67/0058 20130101; C03C 11/002 20130101; C03C 11/005 20130101;
C03B 19/1075 20130101; Y02E 60/32 20130101; B01D 69/00 20130101;
B01D 71/04 20130101; C01B 2203/0405 20130101; C01B 3/0026 20130101;
C01B 3/503 20130101; Y02E 60/327 20130101 |
Class at
Publication: |
252/188.25 |
International
Class: |
C06B 23/00 20060101
C06B023/00 |
Goverment Interests
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH AND DEVELOPMENT
[0001] This invention was made with Government support under
Contract No. DE-AC0996-SR18500 awarded by the United States
Department of Energy. The Government has certain rights in the
invention.
Claims
1. A hydrogen storage apparatus comprising: a hollow glass
microsphere having a porous wall surrounding an internal volume;
and, a hydrogen storage material selected from the group consisting
of palladium, alanates, chemical hydrides, and combinations
thereof, positioned within said volume of said hollow glass
microsphere.
2. The hydrogen storage apparatus according to claim 1 wherein said
hollow glass microsphere has a density of between about 0.05 gm/cc
to about 0.50 gm/cc.
3. The hydrogen storage apparatus according to claim 1 wherein said
hollow glass microsphere has a diameter ranging from about 1.0
micron to about 140 microns.
4. The hydrogen storage apparatus according to claim 1 wherein said
porous wall defines a plurality of openings having an average pore
diameter of between about 10 angstroms to about 1000 angstroms.
5. The hydrogen storage apparatus according to claim 1 wherein said
hollow glass microsphere additionally contains a porous coating on
an exterior surface of said microsphere, said porous coating
further defining a semipermeable membrane.
6. The process of making a hydrogen storage apparatus comprising
the steps of: forming a hollow glass microsphere having an
extractable phase; removing said extractable phase, thereby
providing a porous-wall structure permitting communication between
an interior and an exterior of the hollow glass microsphere;
introducing into an interior of said hollow glass microsphere, a
hydrogen storage material wherein said hydrogen storage apparatus
can reversibly release and store hydrogen.
7. The process according to claim 6 comprising the additional step
of providing a selectively permeable coating on an exterior surface
of said microsphere.
8. A process of providing a hydrogen storage apparatus comprising:
forming a porous hollow glass microsphere; introducing through said
pores a hydrogen storage material into an interior of said hollow
glass microsphere; and, thereafter treating said hollow glass
microsphere so as to alter the pore properties.
9. The process according to claim 8 wherein said step of treating
said pores of said hollow glass microspheres comprises a method
selected from the group of methods consisting of providing a
semi-permeable coating, providing a sol gel coating, heat treating
said hollow glass microspheres, and combinations thereof.
Description
FIELD OF THE INVENTION
[0002] This invention is directed towards hollow glass microspheres
and a process of using the microspheres as part of a hydrogen
storage system. The hollow glass microsphere wall defines a series
of pores. The pores facilitate the placement of a hydrogen storage
material within the interior of the hollow glass microsphere. The
porosity of the hollow glass microspheres can thereafter be
modified by either altering or reducing the overall pore size or by
coating the individual hollow glass microspheres so as to maintain
the hydrogen storage material within a sealed interior of the
hollow glass microsphere. The coating and/or the controlled pore
size enables the selective absorption of hydrogen gas through the
walls of the hollow glass microsphere while isolating the hydrogen
storage material encapsulated therein from other external gases and
fluids.
[0003] The hollow glass microspheres can thereafter be subjected to
variations in temperature, pressure, or other release stimulus
triggers to bring about the release of hydrogen gas. Once
dehydrided, the hollow glass microspheres and hydrogen storage
material can be reused so as to once again selectively absorb
hydrogen gas.
BACKGROUND OF THE INVENTION
[0004] The formation of hollow glass microspheres (HGMs) is well
known in the art. The production of hollow glass microspheres has
been described in U.S. Pat. No. 3,365,315 (Beck); U.S. Pat. No.
4,661,137 (Garnier); and U.S. Pat. No. 5,256,180 (Garnier), and
which are incorporated herein by reference.
[0005] It is also known in the art to produce large macrospheres
having hollow glass walls which provide a semipermeable liquid
separation medium for containing absorbents. The production of
macrosphere structures can be seen in reference to U.S. Pat. Nos.
5,397,759 and 5,225,123 to Torobin and which are incorporated
herein by reference. The Torobin references disclose hollow glass
macrospheres comprising multiple particle glass walls. The
reference teaches the use of the macrospheres for gas/liquid
separation and for use with absorbents but does not discuss any
features or characteristics which would make the microspheres
suitable as a hydrogen storage medium.
[0006] U.S. Pat. No. 4,842,620 (PPG Industries) is directed to
non-crystalline silica fibers having porous walls which are used in
gas separation. The fibers described in this application have
different physical characteristics than microspheres and which
makes fibers less desirable with respect to hydrogen separation and
storage capabilities.
[0007] U.S. Pat. No. 6,358,532 (CaP Biotechnology, Inc.) uses
porous-wall hollow glass microspheres for cell clustering and
biomedical uses. The porous-wall structures are designed to readily
release microsphere contents when present within a biotic system.
Alternatively, the microspheres are used to provide a substrate to
support cell growth within the porous-wall structure.
[0008] While the above references disclose a variety of glass
microspheres and porous-wall structures having various uses in
material separation or drug delivery capabilities, there remains
room for improvement and variation within the art.
SUMMARY OF THE INVENTION
[0009] It is at least one aspect of at least one embodiment of the
present invention to provide for a hollow glass microsphere (HGM)
having a diameter range of between about 1.0 micron to about 140
microns, a density of about 0.05 gm/cc to about 0.50 gm/cc, and
having a porous-wall structure having wall openings with an average
pore size of between about 10 angstroms to about 1000 angstroms,
which contains within an interior of the hollow glass microsphere a
hydrogen storage material.
[0010] It is another aspect of at least one embodiment of the
present invention to provide for a hollow glass microsphere
containing therein an effective amount of the hydrogen storage
material palladium, the hollow glass microsphere having a pore size
which prevents the loss of palladium fines from the interior of the
hollow glass microsphere.
[0011] It is at least one aspect of at least one embodiment of the
present invention to provide for a hollow glass microsphere (HGM)
having a diameter range of between about 1.0 to about 140 microns,
a density of about 0.05 gm/cc to about 0.50 gm/cc, and having a
porous-wall structure having wall openings with an average pore
size which may range from about 10 to about 1000 angstroms, and
which contains within an interior of the hollow glass microsphere a
hydrogen storage material, the exterior wall of the hollow glass
microsphere containing a barrier coating sufficient to prevent
gaseous or liquid contaminants from entering an interior of the HGM
while permitting the passage of hydrogen gas through the exterior
wall.
[0012] These and other features, aspects, and advantages of the
present invention will become better understood with reference to
the following description and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A fully enabling disclosure of the present invention,
including the best mode thereof to one of ordinary skill in the
art, is set forth more particularly in the remainder of the
specification, including reference to the accompanying drawing.
[0014] FIG. 1 is a cross sectional view of a hollow glass
porous-wall microsphere containing a hydrogen storage material
within the interior of the microsphere.
[0015] FIG. 2 is a cross sectional view similar to FIG. 1 showing a
microsphere having an exterior coating.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] Reference will now be made in detail to the embodiments of
the invention, one or more examples of which are set forth below.
Each example is provided by way of explanation of the invention,
not limitation of the invention. In fact, it will be apparent to
those skilled in the art that various modifications and variations
can be made in the present invention without departing from the
scope or spirit of the invention. For instance, features
illustrated or described as part of one embodiment can be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention cover such modifications and
variations as come within the scope of the appended claims and
their equivalents. Other objects, features, and aspects of the
present invention are disclosed in the following detailed
description. It is to be understood by one of ordinary skill in the
art that the present discussion is a description of exemplary
embodiments only and is not intended as limiting the broader
aspects of the present invention, which broader aspects are
embodied in the exemplary constructions.
[0017] The hollow glass microspheres of the present invention are
prepared using a special glass composition which after appropriate
heat treatment separates into two continuous glass phases. In the
examples provided herein, one of the phases is rich in silica,
while the other is an extractable phase. The extractable phase is
preferably present in an amount of at least about 30 weight percent
of the total glass composition. However, other porous glass
compositions may be used.
[0018] The extractable phase of the glass composition preferably
includes boron-containing materials such as borosilicates or
alkali-metal borosilicates. Suitable borosilicates and alkali-metal
silicates may be found in reference to the teachings of U.S. Pat.
No. 4,842,620 directed to leachable glass fiber compositions and
which is incorporated herein by reference.
[0019] The extractable and non-extractable glass components are
mixed, melted, quenched, and crushed to a fine glass powder
consisting of individual glass particles having a particle size of
about 5 to 50 microns. The individual glass particles are then
reheated using a gas/oxidizer flame. The glass is raised to a
temperature where a latent blowing agent within the glass, such as
alkali sulfate along with various hydrates, carbonates, and
halides, the selection and use of which are well known in the art,
causes a single bubble to nucleate within each particle of glass.
As the glass particle temperature increases by exposure to the
flame, the glass particle reaches a viscosity where the particle
transforms to a sphere due to the surface tension forces. As the
temperature increases, the pressure within the bubble exceeds the
surface tension/viscous forces value and the bubble expands to form
a hollow glass microsphere. The hollow glass microsphere is then
rapidly quenched to room temperature.
[0020] Preferably, the resulting hollow glass microspheres have
densities in the range of about 0.05 gm/cc to about 0.5 gm/cc and
diameters may range between about 1 to about 140 microns. Once
formed, the hollow glass microspheres may be separated on the basis
of density so as to select and segregate the hollow glass
microspheres according to desired densities. Additionally, it is
possible to separate the HGMs according to the microsphere
diameter.
[0021] The resulting hollow glass microspheres have a glass wall
composition in which the glass is essentially homogeneous. The
hollow glass microspheres may be heat treated to enhance the
glass-in-glass phase separation by mixing the hollow glass
microspheres with carbonaceous materials and heating in the absence
of oxygen to the desired temperature region. After heat treating
the hollow glass microspheres, the homogeneous glass separates into
two continuous glass phases: one extractable and the other rich in
silica. The extractable phase is readily leachable using strong
mineral acids which results in the formation of wall pores within
the remaining silica-rich phase. Suitable mineral acids and methods
for leaching the glass may be seen in reference to U.S. Pat. No.
4,842,620 which is incorporated herein by reference.
[0022] The resulting hollow glass microspheres exhibit a high
degree of cell wall porosity. As used herein, the term "porosity"
means a series of pores and similar openings which either directly
or indirectly define a series of passageways which provide
communication between the interior and the exterior of the hollow
glass microsphere. An average cell wall porosity of about 10
angstroms to about 1000 angstroms can be achieved using this
technology. The cell wall porosity is dependent upon the percentage
of extractable components formulated into the special glass
composition used in the formation of the HGM and the degree of heat
treatment employed. The duration and severity of the extraction
process also can have some influence on the characteristics of the
resulting cell wall pores including size and density of pores
formed.
[0023] As seen in reference to FIG. 1, a cross section through a
hollow glass microsphere 10 is provided. Microsphere 10 comprises a
glass wall having an exterior surface 12 and an interior surface
14. The microsphere 10 further defines a hollow cavity 16 within
the interior of the microsphere. As best seen in reference to the
figure, a plurality of pores 20 are defined within the glass wall
of the microsphere. As illustrated in FIG. 1, a number of the pores
20 provide for communication between an exterior of the hollow
glass microsphere and the interior cavity 16 of the hollow glass
microsphere. Present within the hollow cavity 16 is a hydrogen
absorption material 30. The placement of the hydrogen storage
material within the cavity 16 is provided in greater detail
below.
[0024] Once formed, the porous-wall hollow glass microspheres can
be filled with a hydrogen absorbent such as palladium. To
successfully introduce palladium into the interior of the HGM,
palladium chloride can be forced through the porous glass walls
using pressure. Following the introduction of palladium chloride,
hydrogen is then introduced under pressure to reduce the palladium
chloride to palladium metal. Subsequent heat and vacuum drying may
be used to remove any residual hydrochloric acid or water. This
process can be repeated through several cycles to increase the
amount of palladium ultimately encapsulated within the hollow glass
microsphere.
[0025] Once a desired amount of palladium is present within the
hollow glass microsphere, the porosity of the hollow glass
microsphere wall can be altered or reduced by additional heat
treatment. Alternatively, the pores can be effectively sealed by
applying a coating material 40 such as tetraethyl orthosilicate
solution and as illustrated in FIG. 2. The coating material can be
formulated to permit the diffusion of hydrogen while excluding
other gases.
[0026] The resulting hollow glass microsphere containing a hydrogen
absorbent offers numerous advantages for use with hydrogen
absorbing technologies. For instance, when palladium metal and
other metal hydrides are used in a hydrogen absorption/desorption
process, the hydrogen storage material tends to fracture into
smaller particles or "fines." The resulting fines can clog filters,
limiting gas flow through the filtration bed in hydrogen separation
devices, and/or blocking gas flow in hydrogen storage devices
resulting in an overall loss of efficiency of the hydrogen
absorption/desorption system. However, when encapsulated within the
hollow glass microsphere, the resulting fines are contained within
the hollow glass microsphere and continue to function in an
absorption/desorption capacity.
[0027] Additionally, it is possible to select HGMs having a
sufficiently small pore size such that gaseous poisons which may
interfere with the hydrogen absorbing material are physically
excluded from entry into the interior of the HGM. As a result, the
HGM functions as a selective membrane which permits the flow of
hydrogen gas into and out of the hollow glass microsphere while
preventing the entry of larger gaseous or liquid molecules.
[0028] While it is possible to force hydrogen into and out of
solid-walled microspheres, the use of a porous-wall hollow glass
microsphere structure allows hydrogen gas to enter and exit the
microsphere at much lower pressures and temperatures. Consequently,
less strenuous rehydriding/dehydriding conditions can be employed
using the porous-wall structure as a conduit to enable the passage
of hydrogen gas through the wall of the glass microsphere.
[0029] Where the pore size of the resulting hollow glass
microsphere is sufficiently large that gaseous poisons or other
materials could enter, it is possible to provide barrier coatings
to the exterior of the HGM. The various barrier coatings may be
selected for special properties so as to provide for selective
membrane properties. One such coating material is a sol gel
material having a sufficiently defined pore structure that provides
for a barrier against gaseous poisons while permitting the flow of
hydrogen gas therethrough. One such sol gel material may be found
in reference to the commonly assigned U.S. Pat. No. 5,965,482, and
which is incorporated herein by reference.
[0030] The hollow glass microspheres, containing therein a hydrogen
storage material, offer additional advantages within the hydrogen
storage technology field. The hollow glass microspheres used in
accordance with the present invention may have diameters of between
about 1 micron to about 140 microns. Given the size and selectable
particle densities, the resulting hollow glass microspheres have
fluid-like properties which make the hollow glass microspheres
suitable for easier transport and bulk storage. For instance,
transportation of large quantities of the filled hollow glass
microspheres may be made utilizing existing pipelines used to
convey the supplies of petroleum products and/or natural gas.
[0031] Though the collective volume of hydrogen storage material
may contain enormous quantities of stored hydrogen gas, the
transport is much safer in that the hydrogen is stored within a
plurality of discrete hollow glass microsphere vessels. As a
result, the dangers associated with the storage of a comparable
volume of hydrogen gas is greatly lessened since the volume is now
distributed within a large number of individual hollow glass
microsphere vessels. The individual hollow glass microspheres
provide an enhanced level of safety against explosion and fire in
that there are no exposed large volumes of hydrogen gas. For
example, a leak or release of HGMs containing releasable hydrogen
has a much reduced threat of explosion or fire since no free
hydrogen is available. Even if released into flame or high
temperature conditions, the insulating properties of the hollow
glass microspheres are such that the net result is a series of very
small releases of hydrogen gas as opposed to a release of a single
large volume of hydrogen gas.
[0032] While palladium represents one hydrogen storage material
which may be incorporated into the interior of the hollow glass
microspheres, it should be noted that a variety of other hydrogen
storage materials are also suitable for use within the interior of
a porous-wall hollow glass microsphere. Such materials include
sodium aluminum hydride, lithium aluminum hydride, titanium
aluminum hydride, complex hydrides, and various fused or hybrid
hydrogen storage materials such as those described in commonly
assigned PCT application PCT/US03/34980 which is incorporated
herein by reference, and various catalyzed borohydrides as
described in commonly owned U.S. provisional application entitled
"Catalyzed Borohydrides For Hydrogen Storage having Attorney Docket
No. WSR-78-P filed on Aug. 27, 2004, by Express Mail EV504784466US
and which is incorporated herein by reference. and combinations of
these hydrogen storage materials. Additionally, the hollow glass
microspheres can be utilized to provide a "protective environment"
for reactive hydrides or other hydrogen storage materials which
occupy the hollow interior of the porous hollow glass
microsphere.
[0033] It is within the scope of the present invention to provide
for a number of different hydrogen storage materials which may be
contained within the interior of a suitable HGM. Doing so would
allow a plurality of different hydrogen storage media to be
utilized within a given application. For instance, within a given
volume of hollow glass microspheres, there could be two or more
different hydrogen storage materials present within discrete
populations of microspheres having different hydrogen release
properties. In this way, the volume of evolved hydrogen gas may be
controlled or regulated by the appropriate environmental conditions
or stimuli needed to release the hydrogen.
[0034] In addition, the use of the hollow glass microspheres
greatly simplifies commercial recharging of the spent hydrogen
storage material. For instance, where the hollow glass microspheres
containing the hydrogen storage material are used to power a
device, the spent HGM may be removed during a refueling operation
and subsequently recharged. By allowing a separate recharging or
hydrogen absorption process, the HGMs having a hydrogen storage
material can be utilized in various environments such as a
hydrogen-powered motor vehicle. To the extent the vehicle only
needs to provide for a hydrogen release mechanism, the mechanics
and operation of the vehicle may be greatly simplified. Upon
refueling with a fresh supply of HGMs (containing hydrided hydrogen
storage material) the spent HGMs are simply removed for subsequent
rehydriding.
[0035] It is also envisioned that the formation of a hollow glass
microsphere may be simplified by selection of an appropriate
hydrogen storage material to serve as the source of the nucleating
gas. In other words, a hydrogen storage material which, when
heated, may release hydrogen or other inert gas that may be used as
the blowing agent for the resulting microsphere. As a result, it
may be possible to use a hydrogen storage or precursor material
which evolves a nucleating agent when heated. As a result, it may
be possible to form the hollow glass microsphere directly around a
hydrogen storage material.
[0036] Although preferred embodiments of the invention have been
described using specific terms, devices, and methods, such
description is for illustrative purposes only. The words used are
words of description rather than of limitation. It is to be
understood that changes and variations may be made by those of
ordinary skill in the art without departing from the spirit or the
scope of the present invention which is set forth in the following
claims. In addition, it should be understood that aspects of the
various embodiments may be interchanged, both in whole, or in part.
Therefore, the spirit and scope of the appended claims should not
be limited to the description of the preferred versions contained
therein.
* * * * *