Modification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applications
<p>Heterogeneous catalysis plays an important role in the pharmaceutical and petrochemical industries. Due to the poor chemical selectivity in many processes, it is essential to design novel catalysts to resolve this problem. Recently, interstitially modifying transition metal NPs with light e...
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| Format: | Thesis |
| Language: | English |
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2020
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| _version_ | 1826316685389332480 |
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| author | Chen, T |
| author2 | Tsang, E |
| author_facet | Tsang, E Chen, T |
| author_sort | Chen, T |
| collection | OXFORD |
| description | <p>Heterogeneous catalysis plays an important role in the pharmaceutical and petrochemical industries. Due to the poor chemical selectivity in many processes, it is essential to design novel catalysts to resolve this problem. Recently, interstitially modifying transition metal NPs with light elements has become a potential strategy for adjusting surface energy and tuning catalytic activity. However, this new class of catalysts remains relatively unexplored due to a lack of adequate characterisation evidence. </p>
<p>Herein, the work presented in this thesis continues the structural characterisation of the Pd-<sup>int</sup>B/C and Pd-<sup>int</sup>Li/C, reported from previous work, by using a novel combination of analytical techniques that span from the atomic to the macro level. Initially, these characterisations showed that after B and Li incorporation the Pd lattice maintains a face-centred cubic structure, but tolerates structural distortion. These structural distortions can further result in the local formation of the HCP structure. Additionally, the combination of STEM-EELS and ptychography was attempted to directly observe the presence of B and Li at the atomic level. </p>
<p>Meanwhile, in order to broaden the scope of the light element modified catalyst family, attempts were made to alloy Li into the Pt host metal system. It was found that the unit cell of the Pt contracts after thermal treatment at elevated temperature, indicating the formation of the Pt-<sup>sub</sup>Li nano bimetallic alloy. The combination of XPS and ssNMR confirms the presence of Li in the metal framework, in addition to the SXRD. The STEM-ADF imaging reveals the presence of the Pt<sub>7</sub>Li. Seemingly, this is the first report of Pt-Li based NPs synthesis to date. This catalyst displays premium 2,5-bis(hydroxymethyl)furan (BHMF) selectivity when catalysing HMF hydrogenation; this is due to the Li blocking specific, undesired reaction pathways. It is anticipated that such an in-depth investigation will help influence the future design and characterisation of novel, light element alloyed systems. </p>
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| first_indexed | 2024-03-06T22:12:47Z |
| format | Thesis |
| id | oxford-uuid:5260ed27-48e1-40f5-b01a-f03aec96cf77 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:49:23Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | oxford-uuid:5260ed27-48e1-40f5-b01a-f03aec96cf772024-12-08T12:38:25ZModification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applicationsThesishttp://purl.org/coar/resource_type/c_db06uuid:5260ed27-48e1-40f5-b01a-f03aec96cf77Chemistry, InorganicEnglishHyrax Deposit2020Chen, TTsang, ENellist, P<p>Heterogeneous catalysis plays an important role in the pharmaceutical and petrochemical industries. Due to the poor chemical selectivity in many processes, it is essential to design novel catalysts to resolve this problem. Recently, interstitially modifying transition metal NPs with light elements has become a potential strategy for adjusting surface energy and tuning catalytic activity. However, this new class of catalysts remains relatively unexplored due to a lack of adequate characterisation evidence. </p> <p>Herein, the work presented in this thesis continues the structural characterisation of the Pd-<sup>int</sup>B/C and Pd-<sup>int</sup>Li/C, reported from previous work, by using a novel combination of analytical techniques that span from the atomic to the macro level. Initially, these characterisations showed that after B and Li incorporation the Pd lattice maintains a face-centred cubic structure, but tolerates structural distortion. These structural distortions can further result in the local formation of the HCP structure. Additionally, the combination of STEM-EELS and ptychography was attempted to directly observe the presence of B and Li at the atomic level. </p> <p>Meanwhile, in order to broaden the scope of the light element modified catalyst family, attempts were made to alloy Li into the Pt host metal system. It was found that the unit cell of the Pt contracts after thermal treatment at elevated temperature, indicating the formation of the Pt-<sup>sub</sup>Li nano bimetallic alloy. The combination of XPS and ssNMR confirms the presence of Li in the metal framework, in addition to the SXRD. The STEM-ADF imaging reveals the presence of the Pt<sub>7</sub>Li. Seemingly, this is the first report of Pt-Li based NPs synthesis to date. This catalyst displays premium 2,5-bis(hydroxymethyl)furan (BHMF) selectivity when catalysing HMF hydrogenation; this is due to the Li blocking specific, undesired reaction pathways. It is anticipated that such an in-depth investigation will help influence the future design and characterisation of novel, light element alloyed systems. </p> |
| spellingShingle | Chemistry, Inorganic Chen, T Modification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applications |
| title | Modification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applications |
| title_full | Modification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applications |
| title_fullStr | Modification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applications |
| title_full_unstemmed | Modification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applications |
| title_short | Modification of the metal lattice in transition metals by light elements: synthesis, characterisations and catalytic applications |
| title_sort | modification of the metal lattice in transition metals by light elements synthesis characterisations and catalytic applications |
| topic | Chemistry, Inorganic |
| work_keys_str_mv | AT chent modificationofthemetallatticeintransitionmetalsbylightelementssynthesischaracterisationsandcatalyticapplications |