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Liao GJ, Hsueh WH, Yen YH, Shih YC, Wang CH, Wang JH, Luo MF. Decomposition of methanol-d 4 on Rh nanoclusters supported by thin-film Al 2O 3/NiAl(100) under near-ambient-pressure conditions. Phys Chem Chem Phys 2024; 26:5059-5069. [PMID: 38258542 DOI: 10.1039/d3cp05303b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The decomposition of methanol-d4 (CD3OD) on Rh nanoclusters grown by the deposition of Rh vapors onto an ordered thin film of Al2O3/NiAl(100) was studied, with various surface-probe techniques and largely under near-ambient-pressure (NAP) conditions. The results showed a superior reactivity of small Rh clusters (diameter < 1.5 nm) exposed to CD3OD at 5 × 10-3-0.1 mbar at 400 K; the gaseous production of CO and D2 from decomposed methanol-d4 per Rh surface site on the small Rh clusters with diameters of ∼1.1 nm was nearly 8 times that on large ones with diameters of ∼3.5 nm. The promotion of reactivity with decreased cluster size under NAP conditions was evidently greater than that under ultrahigh vacuum conditions. Moreover, the concentration of atomic carbon (C*; where * denotes adsorbate)-a key catalyst poisoner-yielded from the dissociation of CO* from dehydrogenated methanol-d4 was significantly smaller on small clusters (diameter < 1.5 nm). The NAP size effect on methanol-d4 decomposition involved the surface hydroxyl (OH*) from the little co-adsorbed water (H2O*) that was dissociated at a probability dependent on the cluster size. H2O* was more likely dissociated into OH* on small Rh clusters, by virtue of their more reactive d-band structure, and the OH* then effectively promoted the O-D cleavage of methanol-d4, as the rate-determining step, and thus the reaction probability; on the other hand, the OH* limited CO* dissociation on small Rh clusters via both adsorbate and lateral effects. These results suggest that the superior properties of small Rh clusters in both reactivity and anti-poisoning would persist and be highly applicable under "real-world" catalysis conditions.
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Affiliation(s)
- Guan-Jr Liao
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan.
| | - Wen-Hao Hsueh
- Department of Chemistry, National Taiwan Normal University, No. 88, Section 4, Ting-Zhou Road, Taipei, Taiwan.
| | - Yu-Hsiang Yen
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan.
| | - Yi-Chan Shih
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan.
| | - Chia-Hsin Wang
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Jeng-Han Wang
- Department of Chemistry, National Taiwan Normal University, No. 88, Section 4, Ting-Zhou Road, Taipei, Taiwan.
| | - Meng-Fan Luo
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan.
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Liao GJ, Hsueh WH, Yen YH, Shih YC, Wang CH, Wang JH, Luo MF. Decomposition of methanol-d4 on a thin film of Al2O3/NiAl(100) under near-ambient-pressure conditions. J Chem Phys 2023; 158:2887766. [PMID: 37129140 DOI: 10.1063/5.0151135] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 04/17/2023] [Indexed: 05/03/2023] Open
Abstract
We have studied the decomposition of methanol-d4 on thin film Al2O3/NiAl(100) under near-ambient-pressure conditions, with varied surface-probe techniques and calculations based on density-functional theory. Methanol-d4 neither adsorbed nor reacted on Al2O3/NiAl(100) at 400 K under ultrahigh vacuum conditions, whereas they dehydrogenated, largely to methoxy-d3 (CD3O*, * denoting adsorbates) and formaldehyde-d2 (CD2O*), on the surface when the methanol-d4 partial pressure was increased to 10-3 mbar and above. The dehydrogenation was facilitated by hydroxyl (OH* or OD*) from the dissociation of little co-adsorbed water; a small fraction of CD2O* interacted further with OH* (OD*) to form, via intermediate CD2OOH* (CD2OOD*), formic acid (DCOOH* or DCOOD*). A few surface carbonates were also yielded, likely on the defect sites of Al2O3/NiAl(100). The results suggest that alumina not only supports metal clusters but also participates in reactions under realistic catalytic conditions. One may consider accordingly the multiple functions of alumina while designing ideal catalysts.
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Affiliation(s)
- Guan-Jr Liao
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan
| | - Wen-Hao Hsueh
- Department of Chemistry, National Taiwan Normal University, No. 88, Sec. 4, Ting-Zhou Road, Taipei, Taiwan
| | - Yu-Hsiang Yen
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan
| | - Yi-Chan Shih
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan
| | - Chia-Hsin Wang
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
| | - Jeng-Han Wang
- Department of Chemistry, National Taiwan Normal University, No. 88, Sec. 4, Ting-Zhou Road, Taipei, Taiwan
| | - Meng-Fan Luo
- Department of Physics, National Central University, No. 300 Jhongda Road, Jhongli 32054, Taiwan
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