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Pan F.,CAS Institute of Process Engineering | Lu X.,CAS Institute of Process Engineering | Lu X.,United Research Center for Resource and Materials | Wang T.,CAS Institute of Process Engineering | Yan Y.,CAS Institute of Process Engineering
Materials Letters | Year: 2017

Submicron ZSM-5 was fast synthesized from coal series kaolin without organic templates with the assistance of crystal seeds. The crystallization conditions (seeds amount and SiO2/Al2O3 molar ratio), the crystallization processes and the mechanism were investigated. The results clearly indicated that the crystallization time could be shortened to 6 h by adding crystal seeds, and the crystal size was effectively reduced to submicron grade. Crystallization process demonstrated that hexa-coordinated Al of leached metakaolin was totally converted to tetra-coordinated Al, involved in the formation of ZSM-5 skeleton with Si species in the form of Si (1Al) and Si (2Al). The crystallization process of sub-micron ZSM-5 synthesized from coal series kaolin also abode by the solution-mediated transport mechanism. © 2017


Pan F.,CAS Institute of Process Engineering | Lu X.,CAS Institute of Process Engineering | Lu X.,United Research Center for Resource and Materials | Zhu Q.,CAS Institute of Process Engineering | And 5 more authors.
Journal of Materials Chemistry A | Year: 2014

Nano-sized ZSM-5 aggregates have been rapidly synthesized from leached metakaolin by solid-like state conversion. The influence of synthesis conditions such as TPA+/SiO2, NaOH/SiO2 and SiO2/Al2O3 molar ratios on the final products was investigated. The properties of nano-sized ZSM-5 aggregates were characterized by XRD, SEM, HRTEM, 29Si and 27Al MAS NMR, NH3-TPD, TG, N2 adsorption-desorption and particle size analysis. The results clearly showed that nano-sized ZSM-5 aggregates could be obtained within 2 h via solid-like state conversion. SEM revealed that the obtained ZSM-5 aggregates were irregular spheres that consisted of nano-sized crystallites with 30-50 nm. The crystallization process indicated that the size of flaky raw materials gradually decreased and formed nano-sized particles as time prolonged. Therefore, the transformation mechanism followed the solution mediated mechanism, though only a little water was contained in the system. Compared with the conventional hydrothermal route, the solid-like state conversion not only significantly shortened the crystallization time, but also totally avoided the emission of waste liquids. In addition, for the methanol dehydration reaction, the nano-sized ZSM-5 aggregates obtained by this method showed much better catalytic performance, C2-C4 olefin selectivity and longer lifetime to endure coke deposition than the sample obtained by the hydrothermal route. © The Royal Society of Chemistry 2014.


Pan F.,CAS Institute of Process Engineering | Pan F.,University of Chinese Academy of Sciences | Lu X.,CAS Institute of Process Engineering | Lu X.,United Research Center for Resource and Materials | And 8 more authors.
Materials Letters | Year: 2013

Large-mesoporous Al2O3 has been successfully synthesized from calcined coal-series kaolin by using cetyltrimethylammonium bromide(CTAB) as template at room temperature. After calcined at 700°C, the as-synthesized samples have transformed to mesoporous γ-Al 2O3. The mesoporous γ-Al2O3 has a specific area of 253.4 m2 g-1, large pore volume of 1.487 cm3 g-1, and an average pore diameter of 12.9 nm. TEM images show that the calcined mesoporous alumina has wormhole-like pores without long-range ordered framework. A probable formation mechanism of large-mesoporous γ-Al2O3 is also proposed. © 2012 Elsevier B.V. All rights reserved.


Pan F.,CAS Institute of Process Engineering | Pan F.,University of Chinese Academy of Sciences | Lu X.,CAS Institute of Process Engineering | Lu X.,United Research Center for Resource and Materials | And 6 more authors.
Materials Letters | Year: 2014

ZSM-5 was successfully synthesized by a template-free method using coal-series kaolinite as the only silica and alumina source. The physicochemical properties of obtained samples were characterized by XRD, SEM, FT-IR and nitrogen adsorption. According to the results, the relative crystallinity of template free ZSM-5 was ca. 94.2%, and crystal size was about 4.0 μm. Due to the absence of an organic template during the synthesis process, the obtained ZSM-5 samples have an opened pore system and could avoid calcination, which could reduce the cost and avoid generating environmental pollution. Furthermore, the process of heterogeneous synthesis for ZSM-5 using kaolinite as a silica source without an organic template has been discussed. © 2013 Elsevier B.V.


Pan F.,CAS Institute of Process Engineering | Pan F.,University of Chinese Academy of Sciences | Lu X.,CAS Institute of Process Engineering | Lu X.,United Research Center for Resource and Materials | And 6 more authors.
Microporous and Mesoporous Materials | Year: 2014

Calcined coal-series kaolinite was used as a combinational Si and Al sources to synthesize ZSM-5 via an organic template-free method. The influence factors such as ball-milling time, H2O/SiO2 ratios, and NaOH/SiO2 ratios have been investigated systematically. Furthermore, crystallization kinetics experiments were performed at 170-190 C for periods of time ranging from 6 to 96 h, and obtained the curves as a function of time. The obtained samples were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that ZSM-5 with excellent crystallinity could be obtained without organic template. Furthermore, mechanical treatment and synthesis conditions could influence the crystallinity and purity significantly. According to Arrhenius equation, the apparent activation energy for induction and growth were 78.3 and 68.5 kJ/mol, respectively. © 2013 Elsevier Inc. All rights rese.


Zhang Z.,Chinese Academy of Sciences | Lu X.,Chinese Academy of Sciences | Lu X.,United Research Center for Resource and Materials | Wang T.,Chinese Academy of Sciences | And 3 more authors.
Journal of Analytical and Applied Pyrolysis | Year: 2014

The dehydration of MgCl2·6H2O in MgCl2·6H2O-NH4Cl-KCl system was investigated. The dehydration process was characterized by X-ray diffraction and chemical analysis. The dehydration effects of MgCl2·6H2O in different systems were compared. The dehydration mechanism of MgCl2·6H2O in MgCl2·6H2O-NH4Cl-KCl system was proposed and discussed. The formation of NH4ClMgCl2·nH2O (6 > n ≥ 0) below 300 °C can effectively suppress hydrolysis. The anhydrous KMgCl3 formed above 400 °C is more stable than anhydrous MgCl2 at elevated temperature, which can effectively protect the dehydration product from hydrolyzing at high temperature. The content of MgO in anhydrous MgCl2 was 0.02 wt.% when dehydrating MgCl2·6H2O in MgCl2·6H2O-KCl-NH4Cl system with the molar ratio of MgCl2·6H2O:KCl:NH4Cl was 1:2.87:1. © 2014 Elsevier B.V. All rights reserved.


Chen S.,CAS Institute of Process Engineering | Chen S.,University of Chinese Academy of Sciences | Lu X.,CAS Institute of Process Engineering | Lu X.,United Research Center for Resource and Materials | And 2 more authors.
Journal of Polymer Research | Year: 2015

High modulus and thermal stability of polyimide (PI)/reactive halloysite nanotubes (HNTs) nanocomposites were prepared by in situ polymerization. The pristine HNTs were firstly handled with the tetraethoxysilane (TEOS) and secondly grafted with the silane agent. The fourier transform infrared spectroscopy (FTIR) approved that TEOS was beneficial for the silane agent to modify the HNTs. Scanning electron microscopy (SEM) showed the differences of the morphology between the reactive HNTs and pristine HNTs. PI/reactive HNTs nanocomposites exhibited lower moisture absorption than pure polyimide. The reactive HNTs reduced the transmittance of the nanocomposites. Significant improvements in the thermal stability and glass transition temperature (Tg) of PI/reactive HNTs nanocomposites were achieved by addition of only a small amount of reactive HNTs. It was noteworthy that both the tensile strength and Young’ modulus of PI/reactive HNTs nanocomposites were significantly enhanced. A 62.8 % increase in tensile strength and a 63.7 % increase in Young’ modulus of the nanocomposites with 3 wt.% of the reactive HNTs were achieved. Finally, the preparation mechanism to obtain PI/reactive HNTs nanocomposites was proposed. © 2015, Springer Science+Business Media Dordrecht.


Pan F.,CAS Institute of Process Engineering | Pan F.,University of Chinese Academy of Sciences | Lu X.,CAS Institute of Process Engineering | Lu X.,United Research Center for Resource and Materials | And 6 more authors.
Applied Clay Science | Year: 2013

Mesoporous γ-Al2O3 has been successfully synthesized by using calcined coal-series kaolin as raw material and Triton X-100 (TX-100) as template. The effect of TX-100/Al3+ ratio on the structural and textural properties of mesoporous γ-Al2O3 was investigated. Physical properties of obtained samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscopy (TEM), thermogravimetric analysis (TG), scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDAX) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the amount of TX-100 influenced the structure and porous properties of mesoporous γ-Al2O3 significantly. When TX-100/Al3+ ratio was in the range of 0.03-0.15, all samples had mesoporous structures with BET surface area of 193.0-261.0m2/g and pore size of 5.04-6.71nm. In addition, the reaction mechanism involved in the process was proposed and discussed. © 2013 Elsevier B.V.


Zhang Z.,Chinese Academy of Sciences | Lu X.,Chinese Academy of Sciences | Lu X.,United Research Center for Resource and Materials | Chen S.,Chinese Academy of Sciences | And 3 more authors.
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2016

To reduce the content of MgOHCl in anhydrous MgCl2, MgOHCl was converted to anhydrous MgCl2 by solid-state reaction. Factors that affect the conversion effects were investigated, including the mol ratio of NH4Cl to MgOHCl, thickness of covering agent, reaction temperature, and reaction time. The conversion process was characterized by XRD analysis and chemical analysis. The solid-state reaction mechanism was studied and discussed. The MgO content in anhydrous MgCl2 achieved 0.05 pct under the optimal conditions: the mol ratio of NH4Cl to MgOHCl was 3:1, thickness of Al2O3 powder 2 cm, reaction temperature 623 K (350 °C), and reaction time 1 hour. © 2015, The Minerals, Metals & Materials Society and ASM International.


Zhang Z.,Chinese Academy of Sciences | Zhang Z.,University of Chinese Academy of Sciences | Lu X.,Chinese Academy of Sciences | Lu X.,United Research Center for Resource and Materials | And 4 more authors.
Industrial and Engineering Chemistry Research | Year: 2012

High-purity anhydrous magnesium chloride was prepared by using magnesia and ammonium chloride as reactants, alumina as covering agent. The process was characterized by X-ray diffraction and thermogravimetric and differential scanning calorimetry analysis. The reaction mechanism involved in the process was proposed and discussed. In addition, the effects of molar ratio of ammonium chloride to magnesia, thickness of the covering agent (alumina), reaction temperature, and reaction time on the purity of anhydrous magnesium chloride were investigated. The content of magnesia in anhydrous magnesium chloride was achieved 0.014% under the optimum conditions: ammonium chloride and magnesia with the molar ratio of NH 4Cl:MgO = 5:1 were mixed evenly. Alumina with the thickness of 1.1 cm was used as a covering agent. The mixture was maintained at 450 °C for 1.5 h for the complete reaction, and then calcined at 700 °C for 0.5 h to obtain well-sintered anhydrous magnesium chloride. © 2012 American Chemical Society.

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