Guang Xiong
Dalian Institute of Chemical Physics
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Featured researches published by Guang Xiong.
Angewandte Chemie | 1999
Can Li; Guang Xiong; Qin Xin; Jianke Liu; Pinliang Ying; Zhaochi Feng; Jian Li; Wu-bin Yang; Yong-zhong Wang; Gui-ru Wang; Xi-yao Liu; Min Lin; Xie-qing Wang; Enze Min
Framework titanium atoms in titanium-substituted silicalite (TS-1) can be identified by UV resonance Raman spectroscopy since the associated Raman bands at 1125, 530, and 490 cm(-1) (see figure) are observed only when the charge transfer transition associated with the framework Ti atoms is excited by a UV laser. Thus, framework Ti atoms can be distinguished from nonframework Ti atoms and other defect sites. This method can be applicable to identifying transition metal atoms in the frameworks of other molecular sieves.
Microporous and Mesoporous Materials | 2001
Yi Yu; Guang Xiong; Can Li; Feng-Shou Xiao
Abstract A series of aluminosilicate zeolites are characterized by UV Raman spectroscopy for the first time, and UV Raman spectra of various zeolites give strong and clear bands with high resolution, while conventional Raman spectra of these zeolites are difficult to obtain because of a strong background fluorescence. Additionally, these zeolites show several new bands in UV Raman spectroscopy. A summary of these UV Raman spectra over various zeolites suggests that the bands at 470–530, 370–430, 290–410, and 220–280 cm −1 can be assigned to the bending modes of 4-, 5-, 6-, and 8-membered rings of aluminosilicate zeolites, respectively. Furthermore, it is found that the band intensity of zeolites in UV Raman spectroscopy is dependent on the Si/Al ratio. Moreover, the UV Raman spectra of crystallization, for zeolite X at various times show that, in the initial stage of crystallization, the 4-membered rings (510 cm −1 ) interconnect each other to form β-cages with 6-membered rings (390 cm −1 ), which further crystallize to zeolite X.
Microporous and Mesoporous Materials | 2001
Guang Xiong; Yi Yu; Zhaochi Feng; Qin Xin; Feng-Shou Xiao; Can Li
The synthesis of zeolite X is characterized by UV Raman spectroscopy, NMR spectroscopy, and X-ray diffraction. UV Raman spectra of the liquid phase of the synthesis system indicate that AI(OH); species are incorporated into silicate species, and the polymeric silicate species are depolymerized into monomeric silicate species during the early stage of zeolite formation. An. intermediate species possessing Raman bands at 307, 503, 858 and 1020 cm(-1) is detected during the crystallization ill the solid phase transformation. The intermediate species is attributed to the beta cage, the secondary building unit of zeolite X. A model for the formation of zeolite X is proposed, which involves four-membered rings connecting to each other via six-membered ring to form beta cages, then the beta cages interconnect via double six-membered rings to form the framework of zeolite X
Microporous and Mesoporous Materials | 2000
Juan Li; Guang Xiong; Zc Feng; Zhongmin Liu; Qin Xin; Can Li
coke formation on/in zsm-5, usy and sapo-34 zeolites was investigated during the methanol conversion to olefins at temperatures from 298 to 773 k using ultraviolet (uv) raman spectroscopy. the fluorescence interference that usually obscures the raman spectra of zeolites in the conventional raman spectroscopy, particularly for coked catalysts, can be successfully avoided in the uv raman spectroscopy. raman spectra are almost the same for adsorbed methanol on the three zeolites at room temperature. however, the raman spectra of the surface species formed at elevated temperatures are quite different for the three zeolites. coke species formed in/on sapo-34 are mainly polyolefinic species, and in/on zsm-5 are some aromatic species, but polyaromatic or substituted aromatic species are predominant in usy at high temperatures. most of the coke species can be removed after a treatment with o-2 at 773 k, while some small amount of coke species always remains in these zeolites, particularly for usy. the main reason for the different behavior of coke formation in the three zeolites could be attributed to the different pore structures of the zeolites. (c) 2000 elsevier science b.v. all rights reserved.
Separation and Purification Technology | 2003
X.L. Pan; Norbert Stroh; Herwig Brunner; Guang Xiong; Shishan Sheng
Highest ratio of separation area to volume of membranes can be achieved by the use of hollow fiber configuration. Ceramic hollow fibers with outer diameters no larger than 1 mm are used as supports for dense Pd membranes. Pd layers of 2/3 mm thick are deposited by electroless plating technique. H2 permeances are 7/10 m 3 /m 2 h bar at 350/ 450 8C. The durability in H2 is tested at 430 8C for 800 h. H2 permeance keeps over 10 m 3 /m 2 h bar and the separation factor of H2/N2 over 1000, which shows the possibilities to be applied in H2 separation and catalysis at high temperatures.
Chemical Communications | 2001
Xiulian Pan; Guang Xiong; Shishan Sheng; Norbert Stroh; Herwig Brunner
Macroporous α-Al2O3 hollow fibers are used as supports for thin dense Pd membranes; these membranes show a high and stable H2 flux in permeance studies.
Catalysis Letters | 1999
Shenglin Liu; Guoxing Xiong; Weishen Yang; Longya Xu; Guang Xiong; Can Li
The catalytic activity, thermal stability and carbon deposition of various modified NiO/γ‐Al2O3 and unmodified NiO/γ‐Al2O3 catalysts were investigated with a flow reactor, XRD, TG and UVRRS analysis. The activity and selectivity of the NiO/γ‐Al2O3 catalyst showed little difference from those of the modified nickel‐based catalysts. However, modification with alkali metal oxide (Li, Na, K) and rare earth metal oxide (La, Ce, Y, Sm) can improve the thermal stability of the NiO/γ‐Al2O3 and enhance its ability to suppress carbon deposition during the partial oxidation of ethane (POE). The carbon deposition contains graphite‐like species that were detected by UVRRS. The nickel‐based catalysts modified by alkali metal oxide and rare earth metal oxide have excellent catalytic activities (C2H6 conversion of ~100%, CO selectivity of ~94%, 7 × 104 l/(kg h), 1123 K), good thermal stability and carbon‐deposition resistance.
Angewandte Chemie | 1999
Can Li; Guang Xiong; Qin Xin; Jianke Liu; Pinliang Ying; Zhaochi Feng; Jian Li; Wu-bin Yang; Yong-zhong Wang; Gui-ru Wang; Xi-yao Liu; Min Lin; Xie-qing Wang; Enze Min
Gerusttitanatome im Ti-substituierten Silicalit-1 (TS-1) konnen UV-Resonanz-Raman-spektroskopisch identifiziert werden, da die zugehorigen Raman-Banden bei 1125, 530 und 490 cm−1 (siehe Abbildung) nur beobachtet werden, wenn der Charge-Transfer-Ubergang der in das Gerust eingebauten Titanatome mit einem UV-Laser angeregt wird. So lassen sich Gerusttitanatome von Nichtgerusttitanatomen und anderen Defektstellen unterscheiden. Mit dieser Methode sollten sich auch Ubergangsmetallatome in den Gerusten anderer Molekularsiebe identifizieren lassen.
Chemical Communications | 2000
Guang Xiong; Can Li; Hongyuan Li; Qin Xin; Zhaochi Feng
Vanadium species in tetrahedral and octahedral coordination in V-MCM-41 molecular sieve are characterized by UV resonance Raman bands at 1070 and 930 cm−1 respectively.
Physical Chemistry Chemical Physics | 2001
Yi Yu; Jihong Yu; Guang Xiong; Can Li; Feng-Shou Xiao
Boron aluminum oxo chloride [BAC(10)], a microporous material, and its crystallization were investigated by X-ray diffraction (XRD), adsorption isotherms of probing molecules, infrared (IR), magic-angle spinning nuclear magnetic resonance (MAS NMR), visible Raman and ultraviolet (UV) Raman spectroscopy. XRD and adsorption isotherms indicate that BAC(10) consists of novel microporous crystals, and IR and NMR results confirmed that the primary building units are triangular BO3, tetrahedral BO4 and octahedral AlO6. No Raman signal in the visible Raman spectrum of BAC(10) was detected owing to the weakness of Raman scattering and strong fluorescence interference. However, strong Raman bands of this material were observed in the UV Raman spectra owing to the avoidance of fluorescence. The UV Raman spectra show that, during the crystallization process, the number of BO3 groups (bands at 300700 cm-1) decrease with increasing number of BO4 groups (bands at 9001000 cm-1) in the solid phase. These results suggest that in the crystallization of BAC(10), the polyborate anions are quickly depolymerized to monoborate species including BO3 and BO4 groups, which are then gradually crystallized to the framework of microporous BAC(10).