ChemWiki - User contributions [en]

It:h3nbh3

2006-12-15T10:05:34Z

Dw104:

Ammonia Borane is a coordination compound which has been recently discovered to be a good source of hydrogen for future hydrogen-fuelled engines.

{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}} colspan="3" |Structure of Ammonia Borane
|-
| align="center" colspan="3" bgcolor="#ffffff" | [[Image:ammonia-borane.gif|200px{{PAGENAME}}]]
|-
! {{chembox header}} colspan="3" |3D structure
|-
| align="center" colspan="3" bgcolor="#ffffff" | <jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
ATOM 1 H 0 1.255 -0.989 0.559 0.00 0.00 H+0
ATOM 2 B 0 0.830 -0.000 0.005 0.00 0.00 B+0
ATOM 3 H 0 1.191 0.001 -1.150 0.00 0.00 H+0
ATOM 4 N 0 -0.679 -0.000 0.061 0.00 0.00 N+0
ATOM 5 H 0 -1.778 -0.000 0.102 0.00 0.00 H+0
ATOM 6 H 0 -0.699 0.953 -0.487 0.00 0.00 H+0
ATOM 7 H 0 -0.699 -0.952 -0.489 0.00 0.00 H+0
ATOM 8 H 0 1.255 0.987 0.561 0.00 0.00 H+0
CONECT 2 1 3 4 8 NONE 13
CONECT 4 2 5 6 7 NONE 14
MASTER 0 0 0 0 0 0 0 0 3 14 0 14 0
END</inlineContents>
</jmolApplet>
</jmol>
|-
| align="center" colspan="3" bgcolor="#ffffff" |
|-
| [[CA Index Name]]
| colspan="2"| Boron, amminetrihydro-, (T-4)- (9CI)
|-
| [[Systematic Name]]
|colspan="2"| Ammonia Borane
|-
| [[Other Name]]
|colspan="2"|Borazane [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]
|-
| [[Chemical formula|Molecular formula]]
| colspan="2" | BH6N
|-
| [[Molar mass]]
| colspan="2" |30.87 g/mol
|-
| [[CAS registry number|CAS number]]
| colspan="2" | 13774-81-7
|-
| [[Appearance]]
| colspan="2" | white crystalline solid
|-
! {{chembox header}} colspan="3"| Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| colspan="2" | 0.780 g/cm3
|-
| [[Solubility]] in [[Water_(molecule)|water (ph=7)]]
| colspan="2" |
|-
| [[Melting point]]
| colspan="2" | 111-114°C
|-
| [[Boiling point]]
| colspan="2" | decomposes
|-
| [[Acid dissociation constant|Acidity]] (p''Ka'') 
| colspan="2" |
|-
| [[Enthalpy of Vaporization]]
| colspan="2" |
|-
! {{chembox header}} colspan="3"| Structure
|-
| [[Crystal structure]] 
| colspan="2"|C4V Symmetry; unit cell is tetragonal
|-
| [[Dipole#Molecular_dipoles|Dipole moment]]
| colspan="2" |5.2[[Debye|D]]
|-
| {{chembox header}} colspan="3"| Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

==Properties==
Although ammonia borane is isoelectronic with ethane, ammonia borane is a solid while ethane is a gas with m.p. of −181°C; and there is a difference of 284°C between their melting points. [http://en.wikipedia.org/wiki/Ammonia_borane]

==Synthesis==
Ammonia Borane is formed from a subsitution reaction:

BH3(THF) + NH3 → BH3NH3 + THF

==Uses==

When heated, ammonia-borane releases two thirds of its hydrogen atoms at relatively low temperatures: 110 and 150 C.

H3BNH3 (l) → H2BNH2 (s) + H2 (g) approx. 137ºC (410.15K)

x(H2BNH2)(s) → (H2BNH2)x (s) approx. 125ºC (398.15K)

(H2BNH2)x(s) → (HBNH)x (s) + xH2 (g) approx. 155ºC (428.15K)

(HBNH)x (s) → (HBNH)3 + other products

(HBNH)3 → 3BN + 3H2 above 500ºC (773.15K)

(H2BNH2)x (s) → (BN)x (s) + 2x H2 (g) approx. 450ºC (723.15K)

[http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b15.pdf]

==Applications==

Vehicles can run on hydrogen-powered, environmentally-friendly fuel cells instead of gasoline engines. Replacing non-renewable fossil fuel with hydrogen has a lot of benefits. In a fuel cell, hydrogen can burn with oxygen to release energy and produce water. This reaction does not generate pollutants such as greenhouse gases and hence reducing the level of pollution, as well as reducing the dependency on fossil fuels which its demand is increasing everyday. [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]

However, the problem is how to store and carry the hydrogen, which can be released when needed. As ammonia borane decomposes, it evolves hydrogen is evolved at a slow rate on heating at below 80°C; where it firstly polymerize to (NH2BH2)n, and then to (NHBH)n.

In order to increase the rate of hydrogen releasing process, a nanoscale mesoporous silica material is used. In this way, the hydrogen can be released at a lower temperature, i.e. below 80°C. It is important to keep the reaction temperature low because additional energy is not required to maintain the reaction. Once the compound is heated sufficiently, the decomposition reaction will proceed on its own. [http://www.azonano.com/details.asp?ArticleID=1164]

==Drawbacks to its use for hydrogen storage==

Ammonia Borane is not made on an industrial scale and so the cost depends on the synthesis technique and processes. The table below compares the cost of other hydrogen storing hydride compounds with that of ammonia borane.

{| border="1"
|+ Table showing the required mass, volume of various Chemical Hydrides required, producing 8 kWh of power.
! Storer !! Mass, kg !! Volume, Litres !! Cost, US$
|-
! LiH
| 1.7 || 3.7 || 109
|-
! CaH2
| 4.5 || 4.0 || 104
|-
! NaBH4 (aq) (35% wt)
| 6.21 || 6.21 || 102
|-
! H3BNH3
| 2.38 || 3.21 || Roughly 390 - 525
|}
[http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b15.pdf]

The high cost is, in part, due to the energy requirements in producing the ammonia reagent from methane. This requires 27 giga Joules per metric ton of NH3 produced using the steam methane reformation process.

CH4 (g) + 0.3035 O2 (g) + 1.131 N2 (g) + 1.393 H2O (g) → CO2 (g) + 2.262 NH3 (g)

The main by-product of ammonia borane’s decomposition is boron nitride (BN). This compound can be collected after use and recycled to produce the original fuel. An idealistic process is show below,

CH4 (g) + 1.33 BN (s) + 2 H2O (g) → CO2 (g) + 1.33 H3BNH3 (g)

This would have to be performed at kinetically unfavourable low temperatures and high pressures, in order to make sure decomposition of the product does not occur.

The manufacture and recycling of ammonia borane and its by products poses a further problem that has no easy solution. The so called “hydrogen economy” is envisaged to halt our energy dependence on fossil fuels. However, if no alternative synthesis pathway is found, the use of ammonia borane will vastly increase our dependence on methane, of which the current main source is natural gas deposits.

==Future Plans==
Further development on this field will eventually lend to a reversible reaction, and would be able to allow the storage material to be regenerated, as well as providing a sustainable hydrogen storage compound with a longer lifetime.

==References==
http://pubs.acs.org/cen/coverstory/83/8334altenergy.html

http://en.wikipedia.org/wiki/Ammonia_borane

http://www.azonano.com/details.asp?ArticleID=1164

http://www.americanscientist.org/template/AssetDetail/assetid/45942

http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b15.pdf

It:h3nbh3

2006-12-13T16:53:46Z

Dw104:

Ammonia Borane is a coordination compound which has been recently discovered to be a good source of hydrogen for future hydrogen-fuelled engines.

{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}} colspan="3" |Structure of Ammonia Borane
|-
| align="center" colspan="3" bgcolor="#ffffff" | [[Image:ammonia-borane.gif|200px{{PAGENAME}}]]
|-
! {{chembox header}} colspan="3" |3D structure
|-
| align="center" colspan="3" bgcolor="#ffffff" | <jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
ATOM 1 H 0 1.255 -0.989 0.559 0.00 0.00 H+0
ATOM 2 B 0 0.830 -0.000 0.005 0.00 0.00 B+0
ATOM 3 H 0 1.191 0.001 -1.150 0.00 0.00 H+0
ATOM 4 N 0 -0.679 -0.000 0.061 0.00 0.00 N+0
ATOM 5 H 0 -1.778 -0.000 0.102 0.00 0.00 H+0
ATOM 6 H 0 -0.699 0.953 -0.487 0.00 0.00 H+0
ATOM 7 H 0 -0.699 -0.952 -0.489 0.00 0.00 H+0
ATOM 8 H 0 1.255 0.987 0.561 0.00 0.00 H+0
CONECT 2 1 3 4 8 NONE 13
CONECT 4 2 5 6 7 NONE 14
MASTER 0 0 0 0 0 0 0 0 3 14 0 14 0
END</inlineContents>
</jmolApplet>
</jmol>
|-
| align="center" colspan="3" bgcolor="#ffffff" |
|-
| [[CA Index Name]]
| colspan="2"| Boron, amminetrihydro-, (T-4)- (9CI)
|-
| [[Systematic Name]]
|colspan="2"| Ammonia Borane
|-
| [[Other Name]]
|colspan="2"|Borazane [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]
|-
| [[Chemical formula|Molecular formula]]
| colspan="2" | BH6N
|-
| [[Molar mass]]
| colspan="2" |30.87 g/mol
|-
| [[CAS registry number|CAS number]]
| colspan="2" | 13774-81-7
|-
| [[Appearance]]
| colspan="2" | white crystalline solid
|-
! {{chembox header}} colspan="3"| Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| colspan="2" | 0.780 g/cm3
|-
| [[Solubility]] in [[Water_(molecule)|water (ph=7)]]
| colspan="2" |
|-
| [[Melting point]]
| colspan="2" | 111-114°C
|-
| [[Boiling point]]
| colspan="2" | decomposes
|-
| [[Acid dissociation constant|Acidity]] (p''Ka'') 
| colspan="2" |
|-
| [[Enthalpy of Vaporization]]
| colspan="2" |
|-
! {{chembox header}} colspan="3"| Structure
|-
| [[Crystal structure]] 
| colspan="2"|C4V Symmetry; unit cell is tetragonal
|-
| [[Dipole#Molecular_dipoles|Dipole moment]]
| colspan="2" |5.2[[Debye|D]]
|-
| {{chembox header}} colspan="3"| Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

==Properties==
Although ammonia borane is isoelectronic with ethane, ammonia borane is a solid while ethane is a gas with m.p. of −181°C; and there is a difference of 284°C between their melting points. [http://en.wikipedia.org/wiki/Ammonia_borane]

==Synthesis==
Ammonia Borane is formed from a subsitution reaction:

BH3(THF) + NH3 → BH3NH3 + THF

==Uses==

When heated, ammonia-borane releases two thirds of its hydrogen atoms at relatively low temperatures: 110 and 150 C.

The reaction is NH3BH3 + 2H2O --> NH4+ + BO2- +3H2

==Applications==

Vehicles can run on hydrogen-powered, environmentally-friendly fuel cells instead of gasoline engines. Replacing non-renewable fossil fuel with hydrogen has a lot of benefits. In a fuel cell, hydrogen can burn with oxygen to release energy and produce water. This reaction does not generate pollutants such as greenhouse gases and hence reducing the level of pollution, as well as reducing the dependency on fossil fuels which its demand is increasing everyday. [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]

However, the problem is how to store and carry the hydrogen, which can be released when needed. As ammonia borane decomposes, it evolves hydrogen is evolved at a slow rate on heating at below 80°C; where it firstly polymerize to (NH2BH2)n, and then to (NHBH)n.

In order to increase the rate of hydrogen releasing process, a nanoscale mesoporous silica material is used. In this way, the hydrogen can be released at a lower temperature, i.e. below 80°C. It is important to keep the reaction temperature low because additional energy is not required to maintain the reaction. Once the compound is heated sufficiently, the decomposition reaction will proceed on its own. [http://www.azonano.com/details.asp?ArticleID=1164]

==Drawbacks to its use for hydrogen storage==

Ammonia Borane is not made on an industrial scale and so the cost depends on the synthesis technique and processes. The table below compares the cost of other hydrogen storing hydride compounds with that of ammonia borane.

{| border="1"
|+ Table showing the required mass, volume of various Chemical Hydrides required, producing 8 kWh of power.
! Storer !! Mass, kg !! Volume, Litres !! Cost, US$
|-
! LiH
| 1.7 || 3.7 || 109
|-
! CaH2
| 4.5 || 4.0 || 104
|-
! NaBH4 (aq) (35% wt)
| 6.21 || 6.21 || 102
|-
! H3BNH3
| 2.38 || 3.21 || Roughly 390 - 525
|}
[http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b15.pdf]

The high cost is, in part, due to the energy requirements in producing the ammonia reagent from methane. This requires 27 giga Joules per metric ton of NH3 produced using the steam methane reformation process.

CH4 (g) + 0.3035 O2 (g) + 1.131 N2 (g) + 1.393 H2O (g) → CO2 (g) + 2.262 NH3 (g)

The main by-product of ammonia borane’s decomposition is boron nitride (BN). This compound can be collected after use and recycled to produce the original fuel. An idealistic process is show below,

CH4 (g) + 1.33 BN (s) + 2 H2O (g) → CO2 (g) + 1.33 H3BNH3 (g)

This would have to be performed at kinetically unfavourable low temperatures and high pressures, in order to make sure decomposition of the product does not occur.

The manufacture and recycling of ammonia borane and its by products poses a further problem that has no easy solution. The so called “hydrogen economy” is envisaged to halt our energy dependence on fossil fuels. However, if no alternative synthesis pathway is found, the use of ammonia borane will vastly increase our dependence on methane, of which the current main source is natural gas deposits.

==Future Plans==
Further development on this field will eventually lend to a reversible reaction, and would be able to allow the storage material to be regenerated, as well as providing a sustainable hydrogen storage compound with a longer lifetime.

==References==
http://pubs.acs.org/cen/coverstory/83/8334altenergy.html

http://en.wikipedia.org/wiki/Ammonia_borane

http://www.azonano.com/details.asp?ArticleID=1164

http://www.americanscientist.org/template/AssetDetail/assetid/45942

http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b15.pdf

It:h3nbh3

2006-12-13T16:53:12Z

Dw104:

Ammonia Borane is a coordination compound which has been recently discovered to be a good source of hydrogen for future hydrogen-fuelled engines.

{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}} colspan="3" |Structure of Ammonia Borane
|-
| align="center" colspan="3" bgcolor="#ffffff" | [[Image:ammonia-borane.gif|200px{{PAGENAME}}]]
|-
! {{chembox header}} colspan="3" |3D structure
|-
| align="center" colspan="3" bgcolor="#ffffff" | <jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
ATOM 1 H 0 1.255 -0.989 0.559 0.00 0.00 H+0
ATOM 2 B 0 0.830 -0.000 0.005 0.00 0.00 B+0
ATOM 3 H 0 1.191 0.001 -1.150 0.00 0.00 H+0
ATOM 4 N 0 -0.679 -0.000 0.061 0.00 0.00 N+0
ATOM 5 H 0 -1.778 -0.000 0.102 0.00 0.00 H+0
ATOM 6 H 0 -0.699 0.953 -0.487 0.00 0.00 H+0
ATOM 7 H 0 -0.699 -0.952 -0.489 0.00 0.00 H+0
ATOM 8 H 0 1.255 0.987 0.561 0.00 0.00 H+0
CONECT 2 1 3 4 8 NONE 13
CONECT 4 2 5 6 7 NONE 14
MASTER 0 0 0 0 0 0 0 0 3 14 0 14 0
END</inlineContents>
</jmolApplet>
</jmol>
|-
| align="center" colspan="3" bgcolor="#ffffff" |
|-
| [[CA Index Name]]
| colspan="2"| Boron, amminetrihydro-, (T-4)- (9CI)
|-
| [[Systematic Name]]
|colspan="2"| Ammonia Borane
|-
| [[Other Name]]
|colspan="2"|Borazane [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]
|-
| [[Chemical formula|Molecular formula]]
| colspan="2" | BH6N
|-
| [[Molar mass]]
| colspan="2" |30.87 g/mol
|-
| [[CAS registry number|CAS number]]
| colspan="2" | 13774-81-7
|-
| [[Appearance]]
| colspan="2" | white crystalline solid
|-
! {{chembox header}} colspan="3"| Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| colspan="2" | 0.780 g/cm3
|-
| [[Solubility]] in [[Water_(molecule)|water (ph=7)]]
| colspan="2" |
|-
| [[Melting point]]
| colspan="2" | 111-114°C
|-
| [[Boiling point]]
| colspan="2" | decomposes
|-
| [[Acid dissociation constant|Acidity]] (p''Ka'') 
| colspan="2" |
|-
| [[Enthalpy of Vaporization]]
| colspan="2" |
|-
! {{chembox header}} colspan="3"| Structure
|-
| [[Crystal structure]] 
| colspan="2"|C4V Symmetry; unit cell is tetragonal
|-
| [[Dipole#Molecular_dipoles|Dipole moment]]
| colspan="2" |5.2[[Debye|D]]
|-
| {{chembox header}} colspan="3"| Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

==Properties==
Although ammonia borane is isoelectronic with ethane, ammonia borane is a solid while ethane is a gas with m.p. of −181°C; and there is a difference of 284°C between their melting points. [http://en.wikipedia.org/wiki/Ammonia_borane]

==Synthesis==
Ammonia Borane is formed from a subsitution reaction:

BH3(THF) + NH3 → BH3NH3 + THF

==Uses==

When heated, ammonia-borane releases two thirds of its hydrogen atoms at relatively low temperatures: 110 and 150 C.

The reaction is NH3BH3 + 2H2O --> NH4+ + BO2- +3H2

==Applications==

Vehicles can run on hydrogen-powered, environmentally-friendly fuel cells instead of gasoline engines. Replacing non-renewable fossil fuel with hydrogen has a lot of benefits. In a fuel cell, hydrogen can burn with oxygen to release energy and produce water. This reaction does not generate pollutants such as greenhouse gases and hence reducing the level of pollution, as well as reducing the dependency on fossil fuels which its demand is increasing everyday. [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]

However, the problem is how to store and carry the hydrogen, which can be released when needed. As ammonia borane decomposes, it evolves hydrogen is evolved at a slow rate on heating at below 80°C; where it firstly polymerize to (NH2BH2)n, and then to (NHBH)n.

In order to increase the rate of hydrogen releasing process, a nanoscale mesoporous silica material is used. In this way, the hydrogen can be released at a lower temperature, i.e. below 80°C. It is important to keep the reaction temperature low because additional energy is not required to maintain the reaction. Once the compound is heated sufficiently, the decomposition reaction will proceed on its own. [http://www.azonano.com/details.asp?ArticleID=1164]

==Drawbacks to its use for hydrogen storage==

Ammonia Borane is not made on an industrial scale and so the cost depends on the synthesis technique and processes. The table below compares the cost of other hydrogen storing hydride compounds with that of ammonia borane.

{| border="1"
|+ Table showing the required mass, volume of various Chemical Hydrides required, producing 8 kWh of power.
! Storer !! Mass, kg !! Volume, Litres !! Cost, US$
|-
! LiH
| 1.7 || 3.7 || 109
|-
! CaH2
| 4.5 || 4.0 || 104
|-
! NaBH4 (aq) (35% wt)
| 6.21 || 6.21 || 102
|-
! H3BNH3
| 2.38 || 3.21 || Roughly 390 - 525
|}

The high cost is, in part, due to the energy requirements in producing the ammonia reagent from methane. This requires 27 giga Joules per metric ton of NH3 produced using the steam methane reformation process.

CH4 (g) + 0.3035 O2 (g) + 1.131 N2 (g) + 1.393 H2O (g) → CO2 (g) + 2.262 NH3 (g)

The main by-product of ammonia borane’s decomposition is boron nitride (BN). This compound can be collected after use and recycled to produce the original fuel. An idealistic process is show below,

CH4 (g) + 1.33 BN (s) + 2 H2O (g) → CO2 (g) + 1.33 H3BNH3 (g)

This would have to be performed at kinetically unfavourable low temperatures and high pressures, in order to make sure decomposition of the product does not occur.

The manufacture and recycling of ammonia borane and its by products poses a further problem that has no easy solution. The so called “hydrogen economy” is envisaged to halt our energy dependence on fossil fuels. However, if no alternative synthesis pathway is found, the use of ammonia borane will vastly increase our dependence on methane, of which the current main source is natural gas deposits.

==Future Plans==
Further development on this field will eventually lend to a reversible reaction, and would be able to allow the storage material to be regenerated, as well as providing a sustainable hydrogen storage compound with a longer lifetime.

==References==
http://pubs.acs.org/cen/coverstory/83/8334altenergy.html

http://en.wikipedia.org/wiki/Ammonia_borane

http://www.azonano.com/details.asp?ArticleID=1164

http://www.americanscientist.org/template/AssetDetail/assetid/45942

http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b15.pdf

It:h3nbh3

2006-12-13T16:52:46Z

Dw104:

Ammonia Borane is a coordination compound which has been recently discovered to be a good source of hydrogen for future hydrogen-fuelled engines.

{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}} colspan="3" |Structure of Ammonia Borane
|-
| align="center" colspan="3" bgcolor="#ffffff" | [[Image:ammonia-borane.gif|200px{{PAGENAME}}]]
|-
! {{chembox header}} colspan="3" |3D structure
|-
| align="center" colspan="3" bgcolor="#ffffff" | <jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
ATOM 1 H 0 1.255 -0.989 0.559 0.00 0.00 H+0
ATOM 2 B 0 0.830 -0.000 0.005 0.00 0.00 B+0
ATOM 3 H 0 1.191 0.001 -1.150 0.00 0.00 H+0
ATOM 4 N 0 -0.679 -0.000 0.061 0.00 0.00 N+0
ATOM 5 H 0 -1.778 -0.000 0.102 0.00 0.00 H+0
ATOM 6 H 0 -0.699 0.953 -0.487 0.00 0.00 H+0
ATOM 7 H 0 -0.699 -0.952 -0.489 0.00 0.00 H+0
ATOM 8 H 0 1.255 0.987 0.561 0.00 0.00 H+0
CONECT 2 1 3 4 8 NONE 13
CONECT 4 2 5 6 7 NONE 14
MASTER 0 0 0 0 0 0 0 0 3 14 0 14 0
END</inlineContents>
</jmolApplet>
</jmol>
|-
| align="center" colspan="3" bgcolor="#ffffff" |
|-
| [[CA Index Name]]
| colspan="2"| Boron, amminetrihydro-, (T-4)- (9CI)
|-
| [[Systematic Name]]
|colspan="2"| Ammonia Borane
|-
| [[Other Name]]
|colspan="2"|Borazane [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]
|-
| [[Chemical formula|Molecular formula]]
| colspan="2" | BH6N
|-
| [[Molar mass]]
| colspan="2" |30.87 g/mol
|-
| [[CAS registry number|CAS number]]
| colspan="2" | 13774-81-7
|-
| [[Appearance]]
| colspan="2" | white crystalline solid
|-
! {{chembox header}} colspan="3"| Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| colspan="2" | 0.780 g/cm3
|-
| [[Solubility]] in [[Water_(molecule)|water (ph=7)]]
| colspan="2" |
|-
| [[Melting point]]
| colspan="2" | 111-114°C
|-
| [[Boiling point]]
| colspan="2" | decomposes
|-
| [[Acid dissociation constant|Acidity]] (p''Ka'') 
| colspan="2" |
|-
| [[Enthalpy of Vaporization]]
| colspan="2" |
|-
! {{chembox header}} colspan="3"| Structure
|-
| [[Crystal structure]] 
| colspan="2"|C4V Symmetry; unit cell is tetragonal
|-
| [[Dipole#Molecular_dipoles|Dipole moment]]
| colspan="2" |5.2[[Debye|D]]
|-
| {{chembox header}} colspan="3"| Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

==Properties==
Although ammonia borane is isoelectronic with ethane, ammonia borane is a solid while ethane is a gas with m.p. of −181°C; and there is a difference of 284°C between their melting points. [http://en.wikipedia.org/wiki/Ammonia_borane]

==Synthesis==
Ammonia Borane is formed from a subsitution reaction:

BH3(THF) + NH3 → BH3NH3 + THF

==Uses==

When heated, ammonia-borane releases two thirds of its hydrogen atoms at relatively low temperatures: 110 and 150 C.

The reaction is NH3BH3 + 2H2O --> NH4+ + BO2- +3H2

==Applications==

Vehicles can run on hydrogen-powered, environmentally-friendly fuel cells instead of gasoline engines. Replacing non-renewable fossil fuel with hydrogen has a lot of benefits. In a fuel cell, hydrogen can burn with oxygen to release energy and produce water. This reaction does not generate pollutants such as greenhouse gases and hence reducing the level of pollution, as well as reducing the dependency on fossil fuels which its demand is increasing everyday. [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]

However, the problem is how to store and carry the hydrogen, which can be released when needed. As ammonia borane decomposes, it evolves hydrogen is evolved at a slow rate on heating at below 80°C; where it firstly polymerize to (NH2BH2)n, and then to (NHBH)n.

In order to increase the rate of hydrogen releasing process, a nanoscale mesoporous silica material is used. In this way, the hydrogen can be released at a lower temperature, i.e. below 80°C. It is important to keep the reaction temperature low because additional energy is not required to maintain the reaction. Once the compound is heated sufficiently, the decomposition reaction will proceed on its own. [http://www.azonano.com/details.asp?ArticleID=1164]

==Drawbacks to its use for hydrogen storage==

Ammonia Borane is not made on an industrial scale and so the cost depends on the synthesis technique and processes. The table below compares the cost of other hydrogen storing hydride compounds with that of ammonia borane.

{| border="1"
|+ Table showing the required mass, volume of various Chemical Hydrides required, producing 8 kWh of power.
! Storer !! Mass, kg !! Volume, Litres !! Cost, US$
|-
! LiH
| 1.7 || 3.7 || 109
|-
! CaH2
| 4.5 || 4.0 || 104
|-
! NaBH4 (aq) (35% wt)
| 6.21 || 6.21 || 102
|-
! H3BNH3
| 2.38 || 3.21 || Roughly 390 - 525
|}

The high cost is, in part, due to the energy requirements in producing the ammonia reagent from methane. This requires 27 giga Joules per metric ton of NH3 produced using the steam methane reformation process.

CH4 (g) + 0.3035 O2 (g) + 1.131 N2 (g) + 1.393 H2O (g) → CO2 (g) + 2.262 NH3 (g)

The main by-product of ammonia borane’s decomposition is boron nitride (BN). This compound can be collected after use and recycled to produce the original fuel. An idealistic process is show below,

CH4 (g) + 1.33 BN (s) + 2 H2O (g) → CO2 (g) + 1.33 H3BNH3 (g)

This would have to be performed at kinetically unfavourable low temperatures and high pressures, in order to make sure decomposition of the product does not occur.

The manufacture and recycling of ammonia borane and its by products poses a further problem that has no easy solution. The so called “hydrogen economy” is envisaged to halt our energy dependence on fossil fuels. However, if no alternative synthesis pathway is found, the use of ammonia borane will vastly increase our dependence on methane, of which the current main source is natural gas deposits.

==Future Plans==
Further development on this field will eventually lend to a reversible reaction, and would be able to allow the storage material to be regenerated, as well as providing a sustainable hydrogen storage compound with a longer lifetime.

==References==
http://pubs.acs.org/cen/coverstory/83/8334altenergy.html

http://en.wikipedia.org/wiki/Ammonia_borane

http://www.azonano.com/details.asp?ArticleID=1164

http://www.americanscientist.org/template/AssetDetail/assetid/45942

www1.eere.energy.gov/hydrogenandfuelcells/pdfs/32405b15.pdf

It:h3nbh3

2006-10-30T17:32:58Z

Dw104:

Ammonia Borane is a coordination compound which has been recently discovered to be a good source of hydrogen for future hydrogen-fuelled engines.

{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}} colspan="3" |Structure of Ammonia Borane
|-
| align="center" colspan="3" bgcolor="#ffffff" | [[Image:ammonia-borane.gif|200px{{PAGENAME}}]]
|-
! {{chembox header}} colspan="3" |3D structure
|-
| align="center" colspan="3" bgcolor="#ffffff" | <jmol>
<jmolApplet>
<size>200</size>
<color>white</color>
<script>zoom 100; cpk on;frame 1; move 10 -20 10 0 0 0 0 0 3; delay 1;</script>
<inlineContents>HEADER CSD ENTRY XICKAV
CRYST1 8.5594 6.0337 11.0220 90.00 105.97 90.00 P21/c
SCALE1 0.116831 -0.000000 0.033428 0.000000
SCALE2 -0.000000 0.165736 -0.000000 0.000000
SCALE3 -0.000000 0.000000 0.094368 0.000000
ATOM 1 H 0 1.255 -0.989 0.559 0.00 0.00 H+0
ATOM 2 B 0 0.830 -0.000 0.005 0.00 0.00 B+0
ATOM 3 H 0 1.191 0.001 -1.150 0.00 0.00 H+0
ATOM 4 N 0 -0.679 -0.000 0.061 0.00 0.00 N+0
ATOM 5 H 0 -1.778 -0.000 0.102 0.00 0.00 H+0
ATOM 6 H 0 -0.699 0.953 -0.487 0.00 0.00 H+0
ATOM 7 H 0 -0.699 -0.952 -0.489 0.00 0.00 H+0
ATOM 8 H 0 1.255 0.987 0.561 0.00 0.00 H+0
CONECT 2 1 3 4 8 NONE 13
CONECT 4 2 5 6 7 NONE 14
MASTER 0 0 0 0 0 0 0 0 3 14 0 14 0
END</inlineContents>
</jmolApplet>
</jmol>
|-
| align="center" colspan="3" bgcolor="#ffffff" |
|-
| [[CA Index Name]]
| colspan="2"| Boron, amminetrihydro-, (T-4)- (9CI)
|-
| [[Systematic Name]]
|colspan="2"| Ammonia Borane
|-
| [[Other Name]]
|colspan="2"|Borazane [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]
|-
| [[Chemical formula|Molecular formula]]
| colspan="2" | BH6N
|-
| [[Molar mass]]
| colspan="2" |30.87 g/mol
|-
| [[CAS registry number|CAS number]]
| colspan="2" | 13774-81-7
|-
| [[Appearance]]
| colspan="2" | white crystalline solid
|-
! {{chembox header}} colspan="3"| Properties
|-
| [[Density]] and [[Phase (matter)|phase]]
| colspan="2" | 0.780 g/cm3
|-
| [[Solubility]] in [[Water_(molecule)|water (ph=7)]]
| colspan="2" |
|-
| [[Melting point]]
| colspan="2" | 111-114°C
|-
| [[Boiling point]]
| colspan="2" | decomposes
|-
| [[Acid dissociation constant|Acidity]] (p''Ka'') 
| colspan="2" |
|-
| [[Enthalpy of Vaporization]]
| colspan="2" |
|-
! {{chembox header}} colspan="3"| Structure
|-
| [[Crystal structure]] 
| colspan="2"|C4V Symmetry; unit cell is tetragonal
|-
| [[Dipole#Molecular_dipoles|Dipole moment]]
| colspan="2" |5.2[[Debye|D]]
|-
| {{chembox header}} colspan="3"| Except where noted otherwise, data are given for materials in their [[standard state|standard state (at 25 °C, 100 kPa)]] [[wikipedia:Chemical infobox|Infobox disclaimer and references]]
|-
|}

==Properties==
Although ammonia borane is isoelectronic with ethane, ammonia borane is a solid while ethane is a gas with m.p. of −181°C; and there is a difference of 284°C between their melting points. [http://en.wikipedia.org/wiki/Ammonia_borane]

==Synthesis==
Ammonia Borane is formed from a subsitution reaction:

BH3(THF) + NH3 → BH3NH3 + THF

==Uses==

When heated, ammonia-borane releases two thirds of its hydrogen atoms at relatively low temperatures: 110 and 150 C.

The reaction is NH3BH3 + 2H2O --> NH4+ + BO2- +3H2

==Applications==

Vehicles can run on hydrogen-powered, environmentally-friendly fuel cells instead of gasoline engines. Replacing non-renewable fossil fuel with hydrogen has a lot of benefits. In a fuel cell, hydrogen can burn with oxygen to release energy and produce water. This reaction does not generate pollutants such as greenhouse gases and hence reducing the level of pollution, as well as reducing the dependency on fossil fuels which its demand is increasing everyday. [http://pubs.acs.org/cen/coverstory/83/8334altenergy.html]

However, the problem is how to store and carry the hydrogen, which can be released when needed. As ammonia borane decomposes, it evolves hydrogen is evolved at a slow rate on heating at below 80°C; where it firstly polymerize to (NH2BH2)n, and then to (NHBH)n.

In order to increase the rate of hydrogen releasing process, a nanoscale mesoporous silica material is used. In this way, the hydrogen can be released at a lower temperature, i.e. below 80°C. It is important to keep the reaction temperature low because additional energy is not required to maintain the reaction. Once the compound is heated sufficiently, the decomposition reaction will proceed on its own. [http://www.azonano.com/details.asp?ArticleID=1164]

==Drawbacks to its use for hydrogen storage==

Ammonia Borane is not made on an industrial scale and so the cost depends on the synthesis technique and processes. The table below compares the cost of other hydrogen storing hydride compounds with that of ammonia borane.

{| border="1"
|+ Table showing the required mass, volume of various Chemical Hydrides required, producing 8 kWh of power.
! Storer !! Mass, kg !! Volume, Litres !! Cost, US$
|-
! LiH
| 1.7 || 3.7 || 109
|-
! CaH2
| 4.5 || 4.0 || 104
|-
! NaBH4 (aq) (35% wt)
| 6.21 || 6.21 || 102
|-
! H3BNH3
| 2.38 || 3.21 || Roughly 390 - 525
|}

The high cost is, in part, due to the energy requirements in producing the ammonia reagent from methane. This requires 27 giga Joules per metric ton of NH3 produced using the steam methane reformation process.

CH4 (g) + 0.3035 O2 (g) + 1.131 N2 (g) + 1.393 H2O (g) → CO2 (g) + 2.262 NH3 (g)

The main by-product of ammonia borane’s decomposition is boron nitride (BN). This compound can be collected after use and recycled to produce the original fuel. An idealistic process is show below,

CH4 (g) + 1.33 BN (s) + 2 H2O (g) → CO2 (g) + 1.33 H3BNH3 (g)

This would have to be performed at kinetically unfavourable low temperatures and high pressures, in order to make sure decomposition of the product does not occur.

The manufacture and recycling of ammonia borane and its by products poses a further problem that has no easy solution. The so called “hydrogen economy” is envisaged to halt our energy dependence on fossil fuels. However, if no alternative synthesis pathway is found, the use of ammonia borane will vastly increase our dependence on methane, of which the current main source is natural gas deposits.

==Future Plans==
Further development on this field will eventually lend to a reversible reaction, and would be able to allow the storage material to be regenerated, as well as providing a sustainable hydrogen storage compound with a longer lifetime.

==References==
http://pubs.acs.org/cen/coverstory/83/8334altenergy.html

http://en.wikipedia.org/wiki/Ammonia_borane

http://www.azonano.com/details.asp?ArticleID=1164

http://www.americanscientist.org/template/AssetDetail/assetid/45942

It:h3nbh3

2006-10-30T13:01:30Z

Dw104:

It:h3nbh3

2006-10-30T12:30:06Z

Dw104: