Title of Invention	METHOD FOR GENERATION OF HYDROGEN GAS FROM BOROHYDRIDE
Abstract	The present invention relates to a method for generation of hydrogen comprising: (a) providing a solid composition comprising from 3% to 50% of alkali metal hydroxide or combination thereof; and 50% to 97% of at least one borohydride compound; and (b) adding to the solid composition an aqueous solution of organic acid; said aqueous solution comprising from 0.01 to 2 equivalents of acid; wherein the solid composition and the aqueous solution are substantially free of transition metals from groups 8, 9 and 10.

Title of Invention

METHOD FOR GENERATION OF HYDROGEN GAS FROM BOROHYDRIDE

Abstract

The present invention relates to a method for generation of hydrogen comprising: (a) providing a solid composition comprising from 3% to 50% of alkali metal hydroxide or combination thereof; and 50% to 97% of at least one borohydride compound; and (b) adding to the solid composition an aqueous solution of organic acid; said aqueous solution comprising from 0.01 to 2 equivalents of acid; wherein the solid composition and the aqueous solution are substantially free of transition metals from groups 8, 9 and 10.

Full Text	METHOD FOR GENERATION OF HYDROGEN GAS FROM BOROHYDRIDE This invention relates to a method for generation of hydrogen gas from a borohydride-containing formulation. This method is useful for hydrogen generation in fuel cells. Borohydride-containing compositions are known as hydrogen sources for hydrogen fuel cells, usually in the form of aqueous solutions. Solid borohydridecontaining compositions also have been used. For example, U.S. Pub. No. 2005/0238573 discloses the use of solid sodium borohydride, which is combined with aqueous acid to produce hydrogen. However, the problem of quickly stopping the generation of hydrogen is not adequately addressed by this reference. The problem addressed by this invention is to find a method for generation of hydrogen gas from a borohydride-containing formulation that allows hydrogen generation to be stopped relatively rapidly. STATEMENT OF INVENTION The present invention provides a method for generation of hydrogen comprising: (a) providing a solid composition comprising from 3% to 50% of at least one base', and 50% to 97% of at least one borohydride compound; and (b) adding to the solid composition an aqueous solution of at least one acid; said aqueous solution comprising from 0.01 to 2 equivalents of acid; wherein the solid composition and the aqueous solution are substantially free of transition metals from groups 8, 9 and 10. DETAILED DESCRIPTION Percentages are weight percentages and temperatures are in °C, unless specified otherwise. An "organic acid" is an acidic compound, i.e., one with a pKa which does not contain carbon. A "base" is a compound with a pKa>8 which is solid at 40°C. In one embodiment, the amount of borohydride compound(s) in the solid composition is at least 75%, alternatively at least 85%, alternatively at least 86%, alternatively at least 87%; the amount of base(s) is no more than 25%, alternatively no more than 15%, alternatively no more than 14%, alternatively no more than 13%. In one embodiment of the invention, the amount of base in the solid composition is at least 5%; the amount of borohydride compound is no more than 95%. Preferably, the borohydride compound is a metal salt which has a metal cation from groups 1, 2, 4, 5, 7, 11, 12 or 13 of the periodic table, or a mixture thereof. In one embodiment, the borohydride compound is an alkali metal borohydride or mixture thereof, alternatively it comprises sodium borohydride (SBH) or potassium borohydride or a mixture thereof, alternatively sodium borohydride. Preferably, the base is an alkali metal hydroxide or mixture thereof, alkali metal alkoxide or alkaline earth alkoxide or combination thereof; alternatively it is an alkali metal hydroxide or sodium or potassium methoxide, or mixture thereof; alternatively sodium, lithium or potassium hydroxide or sodium or potassium methoxide, or a mixture thereof alternatively sodium hydroxide or potassium hydroxide; alternatively sodium hydroxide. More than one alkali metal borohydride and more than one base may be present. Preferably, the acid is an organic acid and/or an inorganic acid. In one embodiment of the invention, the acid is an organic acid. Preferably, the organic acid is a carboxylic acid. In one embodiment of the invention, the organic acid is a Cz'Gs dicarboxylic acid, a Cz'Cs hydroxy carboxylic acid, a C2'C5 hydroxy dicarboxylic acid or a combination thereof. More than one organic acid may be present in the aqueous solution. Especially preferred organic acids include malic acid, citric acid, tartaric acid, malonic acid and oxalic acid. In another embodiment of the invention, the acid is an inorganic acid. Preferably, the inorganic acid is a concentrated mineral acid, e.g., hydrochloric acid, sulfuric acid and/or phosphoric acid. Preferably the inorganic acid is not nitric acid or another strongly oxidizing acid. More than one inorganic acid may be present in the aqueous solution. Both organic and inorganic acids may be present in the aqueous solution. In one embodiment of the invention, the aqueous solution contains from 0.1 to 1 equivalents of acid. For this purpose, equivalents are measured as equivalents of hydrogen ion for reaction with borohydride. The aqueous solution also may contain small amounts of additives, e.g., anti-foaming agents, surfactants, etc. Preferably, the aqueous solution contains no more than 10% of anything other than water and acid, alternatively no more than 5%, alternatively no more than 1%. The solid composition of this invention may be in any convenient form. Examples of suitable solid forms include powder, granules, and compressed solid material. Preferably, powders have an average particle size less than 80 mesh (177 um). Preferably, granules have an average particle size from 10 mesh (2000 um) to 40 mesh (425 um). Compressed solid material may have a size and shape determined by the equipment comprising the hydrogen generation system. In one embodiment of the invention, compressed solid material is in the form of a typical caplet used in other fields. The compaction pressure used to form compressed solid material is not critical. The solid composition is substantially free of substances that catalyze hydrolysis of borohydride, e.g., salts of transition metals in groups 8, 9 and 10; such as Co, Ru, Ni, Fe, Rh, Pd, Os, Ir, Pt, or mixtures thereof, and borides of Co and/or Ni. Preferably, the water content of the solid composition is no more than 0.5%, alternatively no more than 0.2%, alternatively no more than 0.1%. Preferably, the solid composition contains less than 20% of anything other than the borohydride compound and the base, alternatively less than 15%, alternatively less than 10%, alternatively less than 5%. Other possible constituents of the solid composition include, e.g., catalysts, acids, anti-foam agents and surfactants. Preferably, the temperature of the solid composition and the aqueous solution are in the range from -60°C to 100°C, alternatively from -40°C to 50°C. The rate of addition may vary depending on the desired rate of hydrogen generation. Preferably, the mixture formed when the solid composition contacts the aqueous solution is not agitated. The method of this invention allows generation of hydrogen with the capability of stopping said generation relatively quickly after stopping the addition of the aqueous solution. This capability is important in hydrogen fuel cells, where power generation on demand is a key concern. Inability to stop the flow of hydrogen is detrimental to rapid on/off operation of the fuel cell. Linearity of hydrogen generation over time and/or the amount of aqueous solution added is also an important capability in a hydrogen fuel cell. Example 1- Generation of Hydrogen Gas from SBH and Aqueous Malic Acid or CoCl2 Mixtures of SBH and NaOH were prepared, as listed in Table 1 below. Approximately 0.5-0.7 grams of each mixture was compacted at 10,000 psi (68.9 kPa) and placed in a reactor that was connected to a reservoir of water. The water in the reservoir was displaced when hydrogen gas was evolved. A solution of 25 wt % malic acid was syringe pumped to the solid at a rate of 100 microliters per minute for ten minutes at which time the pumps were turned off and the amount of water that continued to be displaced was monitored and recorded as a measure of the amount of time (in seconds unless otherwise indicated) elapsed until the hydrogen flow stopped. For times less than 30 minutes, times for two runs are listed. example 3'- Generation of H2 vs. Time from SBH and 4.6% CoCk Mixtures of SBH and NaOH were prepared, as listed in Table 3 below. Generation of hydrogen was performed as described in Example 1, except that 4.6 wt % CoCh in water was added in place of aqueous malic acid. Volume of hydrogen gas evolved was noted at regular time intervals (in minutes) and correlated with time to determine linearity. The correlation coefficients, R2, obtained from data from 1 minute to 20 minutes, also are listed for each material. The results demonstrate that the method of this invention generates hydrogen with a good linear relationship between volume of aqueous solution added and the volume of hydrogen generated, as shown by the higher correlation coefficients in Table 2, relative to those in Table 3. The method also provides better capability for stopping hydrogen generation when flow of aqueous phase is stopped, as shown in Table Removed WE CLAIM 1. A method for generation of hydrogen gas from borohydride comprising: (a) providing a solid composition comprising from 3% to 50% of alkali metal hydroxide or combination thereof; and 50% to 97% of at least one borohydride compound; and (b) adding to the solid composition an aqueous solution of organic acid; said aqueous solution comprising from 0.01 to 2 equivalents of acid; wherein the solid composition and the aqueous solution are substantially free of transition metals from groups 8, 9 and 10. characterized in that the acid is malic acid. 2. The method as claimed in claim 1 wherein said at least one borohydride compound is at least one alkali metal borohydride, and said at least one base is sodium, lithium or potassium hydroxide, sodium or potassium methoxide, or a combination thereof. 3. The method as claimed in claim 2 wherein the solid composition comprises at least 5% of said at least one base and no more than 95% alkali metal borohydride. 4. The method as claimed in claim 3 wherein said at least one alkali metal borohydride is sodium borohydride, potassium borohydride or a combination thereof. 5. The method as claimed in claim 4 wherein the alkali metal borohydride is sodium borohydride and the base is sodium hydroxide. 6. The method as claimed in claim 1 wherein the aqueous solution comprises from 0.1 to 1 equivalents of acid hydrogen ion for reaction with borohydride. 7. The method as claimed in claim 6 wherein the solid composition comprises from 5% to 15% of sodium hydroxide and from 85% to 95% sodium borohydride.

Full Text

METHOD FOR GENERATION OF HYDROGEN GAS FROM BOROHYDRIDE
This invention relates to a method for generation of hydrogen gas from a
borohydride-containing formulation. This method is useful for hydrogen
generation in fuel cells.
Borohydride-containing compositions are known as hydrogen sources for
hydrogen fuel cells, usually in the form of aqueous solutions. Solid borohydridecontaining
compositions also have been used. For example, U.S. Pub. No.
2005/0238573 discloses the use of solid sodium borohydride, which is combined
with aqueous acid to produce hydrogen. However, the problem of quickly
stopping the generation of hydrogen is not adequately addressed by this
reference.
The problem addressed by this invention is to find a method for generation
of hydrogen gas from a borohydride-containing formulation that allows hydrogen
generation to be stopped relatively rapidly.
STATEMENT OF INVENTION
The present invention provides a method for generation of hydrogen
comprising: (a) providing a solid composition comprising from 3% to 50% of at
least one base', and 50% to 97% of at least one borohydride compound; and (b)
adding to the solid composition an aqueous solution of at least one acid; said
aqueous solution comprising from 0.01 to 2 equivalents of acid; wherein the solid
composition and the aqueous solution are substantially free of transition metals
from groups 8, 9 and 10.
DETAILED DESCRIPTION
Percentages are weight percentages and temperatures are in °C, unless
specified otherwise. An "organic acid" is an acidic compound, i.e., one with a
pKa which does not contain carbon. A "base" is a compound with a pKa>8 which is
solid at 40°C.
In one embodiment, the amount of borohydride compound(s) in the solid
composition is at least 75%, alternatively at least 85%, alternatively at least
86%, alternatively at least 87%; the amount of base(s) is no more than 25%,
alternatively no more than 15%, alternatively no more than 14%, alternatively
no more than 13%. In one embodiment of the invention, the amount of base in
the solid composition is at least 5%; the amount of borohydride compound is no
more than 95%. Preferably, the borohydride compound is a metal salt which has
a metal cation from groups 1, 2, 4, 5, 7, 11, 12 or 13 of the periodic table, or a
mixture thereof. In one embodiment, the borohydride compound is an alkali
metal borohydride or mixture thereof, alternatively it comprises sodium
borohydride (SBH) or potassium borohydride or a mixture thereof, alternatively
sodium borohydride. Preferably, the base is an alkali metal hydroxide or
mixture thereof, alkali metal alkoxide or alkaline earth alkoxide or combination
thereof; alternatively it is an alkali metal hydroxide or sodium or potassium
methoxide, or mixture thereof; alternatively sodium, lithium or potassium
hydroxide or sodium or potassium methoxide, or a mixture thereof alternatively
sodium hydroxide or potassium hydroxide; alternatively sodium hydroxide. More
than one alkali metal borohydride and more than one base may be present.
Preferably, the acid is an organic acid and/or an inorganic acid. In one
embodiment of the invention, the acid is an organic acid. Preferably, the organic
acid is a carboxylic acid. In one embodiment of the invention, the organic acid is
a Cz'Gs dicarboxylic acid, a Cz'Cs hydroxy carboxylic acid, a C2'C5 hydroxy
dicarboxylic acid or a combination thereof. More than one organic acid may be
present in the aqueous solution. Especially preferred organic acids include malic
acid, citric acid, tartaric acid, malonic acid and oxalic acid. In another
embodiment of the invention, the acid is an inorganic acid. Preferably, the
inorganic acid is a concentrated mineral acid, e.g., hydrochloric acid, sulfuric acid
and/or phosphoric acid. Preferably the inorganic acid is not nitric acid or another
strongly oxidizing acid. More than one inorganic acid may be present in the
aqueous solution. Both organic and inorganic acids may be present in the
aqueous solution.
In one embodiment of the invention, the aqueous solution contains from
0.1 to 1 equivalents of acid. For this purpose, equivalents are measured as
equivalents of hydrogen ion for reaction with borohydride. The aqueous solution
also may contain small amounts of additives, e.g., anti-foaming agents,
surfactants, etc. Preferably, the aqueous solution contains no more than 10% of
anything other than water and acid, alternatively no more than 5%,
alternatively no more than 1%.
The solid composition of this invention may be in any convenient form.
Examples of suitable solid forms include powder, granules, and compressed solid
material. Preferably, powders have an average particle size less than 80 mesh
(177 um). Preferably, granules have an average particle size from 10 mesh (2000
um) to 40 mesh (425 um). Compressed solid material may have a size and shape
determined by the equipment comprising the hydrogen generation system. In
one embodiment of the invention, compressed solid material is in the form of a
typical caplet used in other fields. The compaction pressure used to form
compressed solid material is not critical.
The solid composition is substantially free of substances that catalyze
hydrolysis of borohydride, e.g., salts of transition metals in groups 8, 9 and 10;
such as Co, Ru, Ni, Fe, Rh, Pd, Os, Ir, Pt, or mixtures thereof, and borides of Co
and/or Ni.
Preferably, the water content of the solid composition is no more than
0.5%, alternatively no more than 0.2%, alternatively no more than 0.1%.
Preferably, the solid composition contains less than 20% of anything other than
the borohydride compound and the base, alternatively less than 15%,
alternatively less than 10%, alternatively less than 5%. Other possible
constituents of the solid composition include, e.g., catalysts, acids, anti-foam
agents and surfactants.
Preferably, the temperature of the solid composition and the aqueous
solution are in the range from -60°C to 100°C, alternatively from -40°C to 50°C.
The rate of addition may vary depending on the desired rate of hydrogen
generation. Preferably, the mixture formed when the solid composition contacts
the aqueous solution is not agitated.
The method of this invention allows generation of hydrogen with the
capability of stopping said generation relatively quickly after stopping the
addition of the aqueous solution. This capability is important in hydrogen fuel
cells, where power generation on demand is a key concern. Inability to stop the
flow of hydrogen is detrimental to rapid on/off operation of the fuel cell.
Linearity of hydrogen generation over time and/or the amount of aqueous
solution added is also an important capability in a hydrogen fuel cell.
Example 1- Generation of Hydrogen Gas from SBH and Aqueous Malic Acid or
CoCl2
Mixtures of SBH and NaOH were prepared, as listed in Table 1 below.
Approximately 0.5-0.7 grams of each mixture was compacted at 10,000 psi (68.9
kPa) and placed in a reactor that was connected to a reservoir of water. The
water in the reservoir was displaced when hydrogen gas was evolved. A solution
of 25 wt % malic acid was syringe pumped to the solid at a rate of 100
microliters per minute for ten minutes at which time the pumps were turned off
and the amount of water that continued to be displaced was monitored and
recorded as a measure of the amount of time (in seconds unless otherwise
indicated) elapsed until the hydrogen flow stopped. For times less than 30
minutes, times for two runs are listed.
example 3'- Generation of H2 vs. Time from SBH and 4.6% CoCk
Mixtures of SBH and NaOH were prepared, as listed in Table 3 below.
Generation of hydrogen was performed as described in Example 1, except that
4.6 wt % CoCh in water was added in place of aqueous malic acid. Volume of
hydrogen gas evolved was noted at regular time intervals (in minutes) and
correlated with time to determine linearity. The correlation coefficients, R2,
obtained from data from 1 minute to 20 minutes, also are listed for each
material.
The results demonstrate that the method of this invention generates
hydrogen with a good linear relationship between volume of aqueous solution
added and the volume of hydrogen generated, as shown by the higher correlation
coefficients in Table 2, relative to those in Table 3. The method also provides
better capability for stopping hydrogen generation when flow of aqueous phase is
stopped, as shown in Table Removed

WE CLAIM
1. A method for generation of hydrogen gas from borohydride comprising:
(a) providing a solid composition comprising from 3% to 50% of alkali metal hydroxide or
combination thereof; and 50% to 97% of at least one borohydride compound; and
(b) adding to the solid composition an aqueous solution of organic acid; said aqueous
solution comprising from 0.01 to 2 equivalents of acid;
wherein the solid composition and the aqueous solution are substantially free of transition metals from groups 8, 9 and 10.
characterized in that the acid is malic acid.
2. The method as claimed in claim 1 wherein said at least one borohydride compound is at least one alkali metal borohydride, and said at least one base is sodium, lithium or potassium hydroxide, sodium or potassium methoxide, or a combination thereof.
3. The method as claimed in claim 2 wherein the solid composition comprises at least 5% of said at least one base and no more than 95% alkali metal borohydride.
4. The method as claimed in claim 3 wherein said at least one alkali metal borohydride is sodium borohydride, potassium borohydride or a combination thereof.
5. The method as claimed in claim 4 wherein the alkali metal borohydride is sodium borohydride and the base is sodium hydroxide.
6. The method as claimed in claim 1 wherein the aqueous solution comprises from 0.1 to 1 equivalents of acid hydrogen ion for reaction with borohydride.
7. The method as claimed in claim 6 wherein the solid composition comprises from 5% to 15% of sodium hydroxide and from 85% to 95% sodium borohydride.

Documents:

268-DEL-2007-Abstract-(01-03-2011).pdf

268-del-2007-abstract.pdf

268-DEL-2007-Claims (30-08-2011).pdf

268-DEL-2007-Claims-(01-03-2011).pdf

268-del-2007-claims.pdf

268-DEL-2007-Correspondence Others-(30-08-2011).pdf

268-del-2007-correspondence-others 1.pdf

268-DEL-2007-Correspondence-Others-(01-03-2011).pdf

268-DEL-2007-Correspondence-Others-(07-03-2011).pdf

268-DEL-2007-Correspondence-Others.pdf

268-del-2007-description (complete).pdf

268-del-2007-form-1.pdf

268-del-2007-form-18.pdf

268-del-2007-form-2.pdf

268-DEL-2007-Form-3-(01-03-2011).pdf

268-DEL-2007-Form-3.pdf

268-del-2007-form-5.pdf

268-DEL-2007-GPA-(01-03-2011).pdf

268-del-2007-gpa.pdf

268-DEL-2007-Petition 137-(01-03-2011).pdf

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Patent Number

250666

Indian Patent Application Number

268/DEL/2007

PG Journal Number

03/2012

Publication Date

20-Jan-2012

Grant Date

17-Jan-2012

Date of Filing

09-Feb-2007

Name of Patentee

ROHM AND HAAS COMPANY

Applicant Address

100 INDEPENDENCE MALL WEST, PHILADELPHIA, PENNSYLVANIA 19106-2399, U.S.A.

Inventors:

#	Inventor's Name	Inventor's Address
1	JOHN HIROSHI YAMAMOTO	129 SUMMER STREET, ANDOVER, MA 01810, U.S.A.

PCT International Classification Number

H05B3/10

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	60/774,258	2006-02-16	U.S.A.