Xianfeng Yi

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The interactions between histidine and metal species play essential roles in a wide range of important biological processes including enzymes catalysis and signal transduction. In this work, solid-state NMR techniques were employed to determine the interaction between histidine and Zn(II) from pH 3.5 to 14. 2D homo- and heteronuclear correlation NMR(More)
The dispersion and coordination of aluminium species on the surface of silica-alumina based materials are essential for controlling their catalytic activity and selectivity. Al and Al are two common coordinations of Al species in the silica network and alumina phase, respectively. Al is rare in nature and was found hitherto only in the alumina phase or(More)
Crystallization of AlPO4-5 with AFI structure under solvent-free conditions has been investigated. Attention was mainly focused on the characterization of the intermediate phases formed at the early stages during the crystallization. The development in the long-range ordering of the solid phases as a function of crystallization time was monitored by XRD,(More)
The carbonylation of methanol with carbon monoxide to generate methyl acetate over Cu-H-MOR and H-MOR zeolites is studied using solid-state NMR spectroscopy. It is found that the catalytic activity of Cu-H-MOR zeolite is much higher than that of H-MOR zeolite. The presence of Cu(+) species enables the stabilization of dimethyl ether, which efficiently(More)
Solid-state NMR experiments and DFT calculations have been carried out to determine the complex structures of coadsorbed (13)C-labeled tert-butanol and NH3 in acidic H-ZSM-5 zeolite. It is found, besides the physically adsorbed tert-butanol/NH4(+) complex on Brønsted acid sites, the tert-butylamine cation is formed as well, confirming the presence of the(More)
SAPO-11 nanosheets with partially filled micropores (N-SAPO-11) and a thickness of 10-20 nm were synthesized using polyhexamethylene biguanide hydrochloride (PHMB) as a mesoporogen and di-n-propylamine (DPA) as a microporous template. After Pt loading (0.5 wt%), the Pt/N-SAPO-11 catalyst exhibits higher selectivity for the isomers and lower selectivity for(More)
The preparation of photocatalysts with high activities under visible-light illumination is challenging. We report the rational design and construction of a zirconium-doped anatase catalyst (S-Zr-TiO2 ) with Brønsted acidity and photoactivity as an efficient catalyst for the degradation of phenol under visible light. Electron microscopy images demonstrate(More)
The methanol to olefins conversion over zeolite catalysts is a commercialized process to produce light olefins like ethene and propene but its mechanism is not well understood. We herein investigated the formation of ethene in the methanol to olefins reaction over the H-ZSM-5 zeolite. Three types of ethylcyclopentenyl carbocations, that is, the(More)
Experimental evidence for the presence of tert-butyl cations, which are important intermediates in acid-catalyzed heterogeneous reactions, on solid acids has still not been provided to date. By combining density functional theory (DFT) calculations with (1)H/(13)C magic-angle-spinning NMR spectroscopy, the tert-butyl cation was successfully identified on(More)
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