Exploring Meso-/Microporous Composite Molecular Sieves with Core-Shell Structures

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	Exploring Meso-/Microporous Composite Molecular Sieves with Core-Shell Structures
	X. F. F. Qian; B. Li; Y. Y. Y. Hu; G. X. X. Niu; Dyhh Zhang; R. C. C. Che; Y. Tang; D. S. S. Su; A. M. Asiri; D. Y. Y. Zhao
	2012
发表期刊	Chemistry-a European Journal
ISSN	0947-6539
卷号	18 期号:3 页码:931-939
摘要	A series of core-shell-structured composite molecular sieves comprising zeolite single crystals (i.e., ZSM-5) as a core and ordered mesoporous silica as a shell were synthesized by means of a surfactant-directed sol-gel process in basic medium by using cetyltrimethylammonium bromide (CTAB) as a template and tetraethylorthosilicate (TEOS) as silica precursor. Through this coating method, uniform mesoporous silica shells closely grow around the anisotropic zeolite single crystals, the shell thickness of which can easily be tuned in the range of 15-100 nm by changing the ratio of TEOS/zeolite. The obtained composite molecular sieves have compact meso-/micropore junctions that form a hierarchical pore structure from ordered mesopore channels (2.4-3.0 nm in diameter) to zeolite micropores (approximate to 0.51 nm). The short-time kinetic diffusion efficiency of benzene molecules within pristine ZSM-5 (approximate to 7.88 x 10(-19) m(2) s(-1)) is almost retainable after covering with 75 nm-thick mesoporous silica shells (approximate to 7.25 x 10(-19) m(2)s(-1)), which reflects the greatly opened junctions between closely connected mesopores (shell) and micropores (core). The core-shell composite shows greatly enhanced adsorption capacity (approximate to 1.35 mmolg(-1)) for large molecules such as 1,3,5-triisopropylbenzene relative to that of pristine ZSM-5 (approximate to 0.4 mmolg(-1)) owing to the mesoporous silica shells. When Al species are introduced during the coating process, the core-shell composite molecular sieves demonstrate a graded acidity distribution from weak acidity of mesopores (predominant Lewis acid sites) to accessible strong acidity of zeolite cores (Lewis and Bronsted acid sites). The probe catalytic cracking reaction of n-dodecane shows the superiority of the unique core-shell structure over pristine ZSM-5. Insight into the core-shell composite structure with hierarchical pore and graded acidity distribution show great potential for petroleum catalytic processes.
部门归属	[qian, xufang f.; li, bin; hu, yuanyuan y.; niu, guoxing x.; zhang, d. yahong h.; che, renchao c.; tang, yi; zhao, dongyuan y.] fudan univ, dept chem, shanghai key lab mol catalysis & innovat mat, adv mat lab, shanghai 200433, peoples r china. [su, dangsheng s.] chinese acad sci, shenyang natl lab mat sci, inst met res, shenyang 110016, peoples r china. [su, dangsheng s.] max planck soc, fritz haber inst, d-14195 berlin, germany. [asiri, abdullah m.; zhao, dongyuan y.] king abdulaziz univ, dept chem, jeddah 21413, saudi arabia. [asiri, abdullah m.; zhao, dongyuan y.] king abdulaziz univ, fac sci, ctr excellence adv mat res, jeddah, saudi arabia.;zhao, dyy (reprint author), fudan univ, dept chem, shanghai key lab mol catalysis & innovat mat, adv mat lab, shanghai 200433, peoples r china.;dyzhao@fudan.edu.cn
关键词	Composite Materials Core-shell Structures Mesoporous Materials Molecular Sieves Zeolites Amorphous Silica-alumina Catalytic Cracking Coke Formation Zeolite Mcm-41 Nanoparticles Fabrication Oil Microspheres Overgrowth
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文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/60191
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	X. F. F. Qian,B. Li,Y. Y. Y. Hu,et al. Exploring Meso-/Microporous Composite Molecular Sieves with Core-Shell Structures[J]. Chemistry-a European Journal,2012,18(3):931-939.
APA	X. F. F. Qian.,B. Li.,Y. Y. Y. Hu.,G. X. X. Niu.,Dyhh Zhang.,...&D. Y. Y. Zhao.(2012).Exploring Meso-/Microporous Composite Molecular Sieves with Core-Shell Structures.Chemistry-a European Journal,18(3),931-939.
MLA	X. F. F. Qian,et al."Exploring Meso-/Microporous Composite Molecular Sieves with Core-Shell Structures".Chemistry-a European Journal 18.3(2012):931-939.