Heterogeneous copper-based catalysts for low-temperature methanol steam reforming
<p>This thesis concerns the development of a new class of methanol steam reforming (MSR) catalyst precursors. The work aims to facilitate advances in on-board, MSR-powered proton exchange membrane fuel cell technology by producing catalysts with high H<sub>2</sub> production rates...
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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2022
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| _version_ | 1797109882230407168 |
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| author | Vickery, W |
| author2 | Tsang, SCE |
| author_facet | Tsang, SCE Vickery, W |
| author_sort | Vickery, W |
| collection | OXFORD |
| description | <p>This thesis concerns the development of a new class of methanol steam reforming (MSR) catalyst precursors. The work aims to facilitate advances in on-board, MSR-powered proton exchange membrane fuel cell technology by producing catalysts with high H<sub>2</sub> production rates and optimal H<sub>2</sub>:CO selectivity.</p>
<p>CuZn-based layered double hydroxides (LDHs) were synthesised and exfoliated using a novel, simple and scalable aqueous miscible organic solvent method to yield catalyst precursors with high surface areas and copper dispersions. This is the first time such methods were used in the preparation of MSR catalysts; a CuZnAl-LDH precursor achieved a BET surface area and copper dispersion percentage of 252 m<sup>2</sup>.g<sup>−1</sup> and 53.9 %, respectively.</p>
<p>It was found that an optimal content of Ce doped into the catalysts suppressed CO production. Many of the catalysts in this work produced a higher H<sub>2</sub>:CO mol ratio than the previous best recorded ratio in literature, 3000 mol<sub>H<sub>2</sub></sub>:mol<sub>CO</sub>, under conditions that favoured higher reverse water gas shift activity; specifically, 27 % less water content and a 70 % lower weight hourly space velocity (WHSV). Notably, a CuZnGaCe catalyst from this work produced 4721 mol<sub>H<sub>2</sub></sub>:mol<sub>CO</sub>, with an activity of 14.4 µmol<sub>H<sub>2</sub></sub>.s<sup>−1</sup>.g<sub>cat</sub>, at 180 °C using a 1.1:1 mol ratio of water/methanol reactants and a 2.03 h<sup>−1</sup> WHSV.</p>
<p>Additionally, this work investigated the previously unsolved structure of lanthanide-doped LDHs with a wide variety of techniques including high resolution-EDX, Ce L<sub>3</sub> edge XAS and DFT analysis; this allowed the structure to be proposed. XAS was also used to analyse catalyst samples from different stages of water gas shift reactions to gather insight on how the catalysts improved selectivity.</p> |
| first_indexed | 2024-03-07T07:46:02Z |
| format | Thesis |
| id | oxford-uuid:d1caf9e3-b2e7-4a2f-9361-662d1b2c4a39 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:46:02Z |
| publishDate | 2022 |
| record_format | dspace |
| spelling | oxford-uuid:d1caf9e3-b2e7-4a2f-9361-662d1b2c4a392023-06-09T07:45:09ZHeterogeneous copper-based catalysts for low-temperature methanol steam reformingThesishttp://purl.org/coar/resource_type/c_db06uuid:d1caf9e3-b2e7-4a2f-9361-662d1b2c4a39EnglishHyrax Deposit2022Vickery, WTsang, SCE<p>This thesis concerns the development of a new class of methanol steam reforming (MSR) catalyst precursors. The work aims to facilitate advances in on-board, MSR-powered proton exchange membrane fuel cell technology by producing catalysts with high H<sub>2</sub> production rates and optimal H<sub>2</sub>:CO selectivity.</p> <p>CuZn-based layered double hydroxides (LDHs) were synthesised and exfoliated using a novel, simple and scalable aqueous miscible organic solvent method to yield catalyst precursors with high surface areas and copper dispersions. This is the first time such methods were used in the preparation of MSR catalysts; a CuZnAl-LDH precursor achieved a BET surface area and copper dispersion percentage of 252 m<sup>2</sup>.g<sup>−1</sup> and 53.9 %, respectively.</p> <p>It was found that an optimal content of Ce doped into the catalysts suppressed CO production. Many of the catalysts in this work produced a higher H<sub>2</sub>:CO mol ratio than the previous best recorded ratio in literature, 3000 mol<sub>H<sub>2</sub></sub>:mol<sub>CO</sub>, under conditions that favoured higher reverse water gas shift activity; specifically, 27 % less water content and a 70 % lower weight hourly space velocity (WHSV). Notably, a CuZnGaCe catalyst from this work produced 4721 mol<sub>H<sub>2</sub></sub>:mol<sub>CO</sub>, with an activity of 14.4 µmol<sub>H<sub>2</sub></sub>.s<sup>−1</sup>.g<sub>cat</sub>, at 180 °C using a 1.1:1 mol ratio of water/methanol reactants and a 2.03 h<sup>−1</sup> WHSV.</p> <p>Additionally, this work investigated the previously unsolved structure of lanthanide-doped LDHs with a wide variety of techniques including high resolution-EDX, Ce L<sub>3</sub> edge XAS and DFT analysis; this allowed the structure to be proposed. XAS was also used to analyse catalyst samples from different stages of water gas shift reactions to gather insight on how the catalysts improved selectivity.</p> |
| spellingShingle | Vickery, W Heterogeneous copper-based catalysts for low-temperature methanol steam reforming |
| title | Heterogeneous copper-based catalysts for low-temperature methanol steam reforming |
| title_full | Heterogeneous copper-based catalysts for low-temperature methanol steam reforming |
| title_fullStr | Heterogeneous copper-based catalysts for low-temperature methanol steam reforming |
| title_full_unstemmed | Heterogeneous copper-based catalysts for low-temperature methanol steam reforming |
| title_short | Heterogeneous copper-based catalysts for low-temperature methanol steam reforming |
| title_sort | heterogeneous copper based catalysts for low temperature methanol steam reforming |
| work_keys_str_mv | AT vickeryw heterogeneouscopperbasedcatalystsforlowtemperaturemethanolsteamreforming |