报告题目：Rational Design for Cooperative Metathesis Sites in USY Catalyst
报告人：Shik Chi Edman TSANG教授
报告题目：Microporous Catalysts for Biomass Conversion and the Advanced Characterisation of by Synchrotron X-ray Powder Diffraction
报告人：Benedict T.W. Lo博士
报告题目：Surface understanding at atomic scale for the rational design of hetero(photo) catalysts
报告人：Yung-Kang Peng博士
报告时间：2019年07月10日（星期三）上午09:00-11:30
报告地点：16号楼214会议室
欢迎广大师生前往！
化学与化工学院
2019年07月09日
报告人简介：
Shik Chi Edman TSANG教授简历请参见
http://research.chem.ox.ac.uk/edman-tsang.aspx.
报告简介：
Mid-4d and 5d transition metal centres in Schrock catalysts which feature solid supported Mo and W, Re metal centres, are effective for industrial olefin metathesis (1,2). To buffer the current imbalance demand/supply in olefins, the catalytic cross-metathesis process to inter-convert olefins can be employed. WO3/SiO2 and Re2O7/Al2O3 based materials are widely used as the industrial catalysts. However, they still suffer from moderately low activity even at higher temperature and pressure. Here, we report a new class of catalytically active single site W and Re species on the internal structure of zeolites for this catalytic reaction (3). A tungstate (WO42-) and trioxo perrhenate (O=)3Re(−O) species are immobilised adjacent to the Brønsted acid site, BAS in H-USY zeolite. We will show that the important role(s) of the BAS which can enhance adsorption of incoming olefin molecules through acid-base interaction as well as aligning the molecules for reaction within the confined space. As the BAS and discrete metathesis site are adjacent to each other, we will also show the formation of the metallocycle intermediate is facilitated based on the structural findings by synchrotron techniques including SXRD and EXAFS (4). In this conference, the approach leading to rational design of encapsulated metathesis zeolite based catalysts for tailored catalytic specificities will be discussed.
1) R. R. Schrock, Tetrahedron. 55, 8141–8153 (1999).
2) A. H. Hoveyda, R. R. Schrock, Chem. Eur. J. 7, 945–950 (2001).
3) P. Zhao et al., J. Am. Chem. Soc. 140, 6661–6667 (2018).
4) B. T. Lo, L. Ye, S. C. E. Tsang, Chem. 4, 1778-1808 (2018).
报告人简介：
Benedict T.W. Lo博士简历请参见https://www.polyu.edu.hk/abct/en/staff/academic_staff/index.php?id=twblo.
报告简介:
Synchrotron X-ray powder diffraction has begun to stretch its strategic presence from the sheer determination of crystal structures into the mechanistic and kinetic information of microporous zeolite materials. Not only can this technique be used to reveal the internal framework structure of zeolites and their active sites, but it can also be combined with other analytical tools to suit the particular needs for in situ or operando gas storage and separation and catalytic studies. With a keen interest in materials and biomass conversion catalysis, our research group has focussed on the fundamental aspects of microporous materials. We have developed a new structural methodology by combining state-of-the-art synchrotron X-ray facilities with other characterisation techniques, that can:
1. Explain the reaction mechanisms and kinetics of new biomass conversion reactions. We reported a novel biomass conversion reaction from ethanol and biomass-derived furan to aromatics via Diels-Alder reaction, followed by dehydration catalysed by H-USY zeolite. The key was to understand the fundamental interactions of ethanol with BAS and the in situ formation of ethene, by our combined experimental and computational studies.
2. Design a novel enzyme-mimic inorganic system. We presented the catalytic conversion of biomass-derived gamma-valerolactone to aromatics at high yield over Zn/ZSM-5. The structure and fundamental pathway of the active nucleophilic Zn-OH site are found to be comparable to the Zn-containing T199A CA II enzyme.
Selected publications:
1. Elucidation of Adsorbate Structures and Interactions on Brønsted Acid Sites in H-ZSM-5 by Synchrotron X-ray Powder Diffraction. Angew. Chem. Int. Ed. 55, 5981–5984 (2016).
2. Entrapped Single Tungstate Site in Zeolite for Cooperative Catalysis of Ole fi n Metathesis with Brønsted Acid Site. J. Am. Chem. Soc. 140, 21, 6661–6667(2018).
3. From Biomass-Derived Furans to Aromatics with Ethanol over Zeolite. Angew. Chem. Int. Ed. 55, 13061–13066 (2016).
4. A New Route for De‐carboxylation of Lactones over Zn/ZSM‐5: Elucidation of Structure and Molecular Interactions. Angew. Chem. Int. Ed. 56, 10711–10716 (2017).
5. The Contribution of Synchrotron X-Ray Powder Diffraction to Modern Zeolite Applications: A Mini-review and Prospects. Chem. 4, 1–31 (2018).
报告人简介：
Yung-Kang Peng博士简历请参见
http://www.cityu.edu.hk/chem/profile/drykp.html.
报告简介：
Altering the exposed facet of a nanocrystallite and hence the control of surface chemistry at the nano level has been intensively studied as an efficient approach to further enhance their catalytic performance. Given that each exposed facet possesses distinctive surface energy, the chemical state (i.e. electron density) of surface atoms, which is closely associated with its Lewis acidity/basicity and hence the adsorption/activation energy of reactant molecules, is expected to vary with its hosted facets[1]. However, surface information provided by conventional surface techniques is far from satisfactory and the factor dictates facet activity is still unclear nowadays. Without a genuine surface tool, there had been different interpretations even disagreements found among researchers on the origin of facet activity in the past decades[2].
Herein, we have developed “probe-assisted NMR” which allows a genuine differentiation of surface features such as oxygen vacancies, hydroxyl groups and cations with various chemical states on their hosted facets. This technique has been demonstrated to provide both qualitative (chemical shift) and quantitative (peak intensity) information on the distribution and concentration of surface features. So far, the comprehensive facet/surface study of ZnO[3], TiO2[4,5], Niobia[6], MgO, CeO2 and composites Pd/MoO3-P2O5[7] by this technique has unambiguously revealed the key active site in their corresponding hetero(photo) catalytic reactions.
References
[1] M. A. Boles, D. Link, T. Hyeon, D. V. Talapin, Nat. Mater., 15 (2016), 141.
[2] Y.-K. Peng, S. C. E. Tsang, Nano Today, 18 (2018), 15.
[3] Y.-K. Peng, L. Ye, J. Qu, L. Zhang, Y. Fu, I. F. Teixeira, I. J. McPherson, H. He, S. C. E. Tsang, J. Am. Chem. Soc., 138 (2016), 2225.
[4] Y.-K. Peng, Y. Hu, H.-L. Chou, Y. Fu, I. F. Teixeira, H. He, S. C. E. Tsang, Nat. Commun., 8 (2017), 675.
[5] Y.-K. Peng, H.-L. Chou, S. C. E. Tsang, Chem. Sci., 9 (2018), 2493.
[6] H. T. Kreissl, M. J. Li, Y.-K. Peng, K. Nakagawa, T. J. N. Hooper, J. V. Hanna, A. Shepherd, T.-S. Wu, Y.-L. Soo, S. C. E. Tsang, J. Am. Chem. Soc., 139 (2017), 12670.
[7] H. Duan, J. Dong, X. Gu, Y.-K. Peng, W. Chen, T. Issariyakul, W. Myers, M.-J. Li, N. Yi, A. Kilpatrick, Y. Wang, X. Zheng, S. Ji, Q. Wang, J. Feng, D. Chen, Y. Li, J.-C. Buffet, H.-C. Liu, S. C. E. Tsang, D. O'Hare, Nat. Commun. 8 (2017), 591.