Decomposition pathway of KAlH4 altered by the addition of Al2S3
Altering the decomposition pathway of potassium alanate, KAlH 4 , with aluminium sulfide, Al 2 S 3 , presents a new opportunity to release all of the hydrogen, increase the volumetric hydrogen capacity and avoid complications associated with the formation of KH and molten K. Decomposition of 6KAlH 4...
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| Format: | Journal Article |
| Language: | English |
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ROYAL SOC CHEMISTRY
2019
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| Online Access: | http://purl.org/au-research/grants/arc/LP120101848 http://hdl.handle.net/20.500.11937/91766 |
| _version_ | 1848765586529583104 |
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| author | Sheppard, Drew Jepsen, L.H. Rowles, Matthew Paskevicius, Mark Jensen, T.R. Buckley, Craig |
| author_facet | Sheppard, Drew Jepsen, L.H. Rowles, Matthew Paskevicius, Mark Jensen, T.R. Buckley, Craig |
| author_sort | Sheppard, Drew |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Altering the decomposition pathway of potassium alanate, KAlH 4 , with aluminium sulfide, Al 2 S 3 , presents a new opportunity to release all of the hydrogen, increase the volumetric hydrogen capacity and avoid complications associated with the formation of KH and molten K. Decomposition of 6KAlH 4 -Al 2 S 3 during heating under dynamic vacuum began at 185 °C, 65 °C lower than for pure KAlH 4 , and released 71% of the theoretical hydrogen content below 300 °C via several unknown compounds. The major hydrogen release event, centred at 276 °C, was associated with two new compounds indexed with monoclinic (a = 10.505, b = 7.492, c = 11.772 Å, β = 122.88°) and hexagonal (a = 10.079, c = 7.429 Å) unit cells, respectively. Unlike the 6NaAlH 4 -Al 2 S 3 system, the 6KAlH 4 -Al 2 S 3 system did not have M 3 AlH 6 (M = alkali metal) as one of the intermediate decomposition products nor were the final products M 2 S and Al observed. Decomposition performed under hydrogen pressure initially followed a similar reaction pathway to that observed during heating under vacuum but resulted in partial melting of the sample between 300 and 350 °C. The measured enthalpy of hydrogen absorption (ΔH abs ) was in the range -44.5 to -51.1 kJ mol -1 H 2 , which is favourable for moderate temperature hydrogen applications. Although, the hydrogen capacity decreases during consecutive H 2 release and uptake cycles, the presence of excess amounts of aluminium allow for further optimisation of hydrogen storage properties. |
| first_indexed | 2025-11-14T11:37:36Z |
| format | Journal Article |
| id | curtin-20.500.11937-91766 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:37:36Z |
| publishDate | 2019 |
| publisher | ROYAL SOC CHEMISTRY |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-917662023-06-06T03:28:27Z Decomposition pathway of KAlH4 altered by the addition of Al2S3 Sheppard, Drew Jepsen, L.H. Rowles, Matthew Paskevicius, Mark Jensen, T.R. Buckley, Craig Science & Technology Physical Sciences Chemistry, Inorganic & Nuclear Chemistry METAL-HYDRIDES HEAT-STORAGE MAGNESIUM HYDRIDE HYDROGEN STORAGE SYSTEM SOLAR THERMODYNAMICS PRESSURE BOROHYDRIDES DIFFRACTION Altering the decomposition pathway of potassium alanate, KAlH 4 , with aluminium sulfide, Al 2 S 3 , presents a new opportunity to release all of the hydrogen, increase the volumetric hydrogen capacity and avoid complications associated with the formation of KH and molten K. Decomposition of 6KAlH 4 -Al 2 S 3 during heating under dynamic vacuum began at 185 °C, 65 °C lower than for pure KAlH 4 , and released 71% of the theoretical hydrogen content below 300 °C via several unknown compounds. The major hydrogen release event, centred at 276 °C, was associated with two new compounds indexed with monoclinic (a = 10.505, b = 7.492, c = 11.772 Å, β = 122.88°) and hexagonal (a = 10.079, c = 7.429 Å) unit cells, respectively. Unlike the 6NaAlH 4 -Al 2 S 3 system, the 6KAlH 4 -Al 2 S 3 system did not have M 3 AlH 6 (M = alkali metal) as one of the intermediate decomposition products nor were the final products M 2 S and Al observed. Decomposition performed under hydrogen pressure initially followed a similar reaction pathway to that observed during heating under vacuum but resulted in partial melting of the sample between 300 and 350 °C. The measured enthalpy of hydrogen absorption (ΔH abs ) was in the range -44.5 to -51.1 kJ mol -1 H 2 , which is favourable for moderate temperature hydrogen applications. Although, the hydrogen capacity decreases during consecutive H 2 release and uptake cycles, the presence of excess amounts of aluminium allow for further optimisation of hydrogen storage properties. 2019 Journal Article http://hdl.handle.net/20.500.11937/91766 10.1039/c9dt00457b English http://purl.org/au-research/grants/arc/LP120101848 http://purl.org/au-research/grants/arc/LP150100730 http://purl.org/au-research/grants/arc/FT160100303 ROYAL SOC CHEMISTRY fulltext |
| spellingShingle | Science & Technology Physical Sciences Chemistry, Inorganic & Nuclear Chemistry METAL-HYDRIDES HEAT-STORAGE MAGNESIUM HYDRIDE HYDROGEN STORAGE SYSTEM SOLAR THERMODYNAMICS PRESSURE BOROHYDRIDES DIFFRACTION Sheppard, Drew Jepsen, L.H. Rowles, Matthew Paskevicius, Mark Jensen, T.R. Buckley, Craig Decomposition pathway of KAlH4 altered by the addition of Al2S3 |
| title | Decomposition pathway of KAlH4 altered by the addition of Al2S3 |
| title_full | Decomposition pathway of KAlH4 altered by the addition of Al2S3 |
| title_fullStr | Decomposition pathway of KAlH4 altered by the addition of Al2S3 |
| title_full_unstemmed | Decomposition pathway of KAlH4 altered by the addition of Al2S3 |
| title_short | Decomposition pathway of KAlH4 altered by the addition of Al2S3 |
| title_sort | decomposition pathway of kalh4 altered by the addition of al2s3 |
| topic | Science & Technology Physical Sciences Chemistry, Inorganic & Nuclear Chemistry METAL-HYDRIDES HEAT-STORAGE MAGNESIUM HYDRIDE HYDROGEN STORAGE SYSTEM SOLAR THERMODYNAMICS PRESSURE BOROHYDRIDES DIFFRACTION |
| url | http://purl.org/au-research/grants/arc/LP120101848 http://purl.org/au-research/grants/arc/LP120101848 http://purl.org/au-research/grants/arc/LP120101848 http://hdl.handle.net/20.500.11937/91766 |