[1] Du XudongLiu ZongjianCui QunWang HaiyanYao Huqing,. Effect of secondary pore distribution on adsorption diffusionperformance of n-hexane on 5A zeolite pellets [J]. Journal of Southeast University (English Edition), 2011, 27 (3): 284-289. [doi:10.3969/j.issn.1003-7985.2011.03.012]

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Effect of secondary pore distribution on adsorption diffusionperformance of n-hexane on 5A zeolite pellets()

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Journal of Southeast University (English Edition)[ISSN:1003-7985/CN:32-1325/N]

Volumn:

27

Issue:

2011 3

Page:

284-289

Research Field:

Chemistry and Chemical Engineering

Publishing date:

2011-09-30

Info

Title:

Effect of secondary pore distribution on adsorption diffusionperformance of n-hexane on 5A zeolite pellets

Author(s):

Du XudongLiu ZongjianCui QunWang HaiyanYao Huqing

College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China

Keywords:

5A zeolite;  pore structure;  secondary pore;  diffusion;  n-hexane

PACS:

TQ028.15;TQ424.25

DOI:

10.3969/j.issn.1003-7985.2011.03.012

Abstract:

Adsorption rates of n-hexane on the 5A zeolite at 100 to 300℃ and 0.01 to 10 kPa are determined by an intelligent gravimetric analyzer(IGA-100), and the adsorption diffusion performance of n-hexane on 5A zeolite pellets with different secondary pore distributions is analyzed. The results indicate that 5A-1 and 5A-6 zeolites have similar micropore and mesopore size distribution, while the 5A-6 zeolite has a larger secondary pore volume when the pore diameter is between 0.1 and 1 μm and more secondary pores when the pore diameter is less than 0.01 μm. The effective diffusion coefficient of n-hexane on the 5A-6 zeolite pellet is 10^-6 to 10^-4 cm²/s, about 2 to 5 times higher than that on the 5A-1 zeolite. The effective diffusion coefficient of n-hexane on the 5A-1 zeolite pellet improves from 5×10^-7 to 2×10^-6cm²/s when the temperature increases from 100 to 300℃. However, the effective diffusion coefficient of n-hexane on the 5A-6 zeolite remains almost unchanged at different temperatures. The molecular average free path of n-hexane decreases from 627.15-963.28 to 0.63-0.96 μm with the adsorption pressure increasing from 0.01 to 10 kPa. Such a free path is close to the secondary pore diameter, resulting in significant Knudsen diffusion in the secondary pores. Thus, the effective diffusion coefficient of n-hexane on the 5A zeolite pellets increases before 1 kPa and decreases after 1 kPa.

References:

[1] Zhao L X, Ma Y, Sun L, et al. Research progress in theory and equipment for hexane production and purification [J]. Modern Chemical Industry, 2009, 29(9): 15-22.(in Chinese)
[2] Wu R D, Ma F, Liu W Z, et al. Research on new environment-friendly solvent oil and the production technology [J]. Shanghai Chemical Industry, 2008, 33(11): 26-30.(in Chinese)
[3] Wang Y W, Liu X X. Production and market status of solvent oils [J]. Techno-Economics in Petrochemicals, 2004, 19(1): 43-46.(in Chinese)
[4] Wang Y F, Xing J X. Status quo and development trends of petroleum hydrocarbon solvent oils [J]. Petroleum Refinery Engineering, 2002, 32(10): 44-47.(in Chinese)
[5] Ba’rcia P S, Silva J, Rodrigues A E. Separation by fixed-bed adsorption of hexane isomers in zeolite BETA pellets [J]. Ind Eng Chem Res, 2006, 45(12): 4316-4328.
[6] Silca J, Rodrigues A E. Equilibrium and kinetics of n-hexane adsorption in pellets of 5A zeolite [J]. AIChE Journal, 1997, 43(10): 2524-2534.
[7] Shen B X, Sun H. Adsorption kinetics of n-pentane and n-hexane on binder-free 5A molecular sieve [J]. Petrochemical Technology, 2008, 37(8): 805-809.(in Chinese)
[8] Ba’rcia P S, Silva J, Rodrigues A E. Adsorption equilibrium and kinetics of branched hexane isomers in pellets of BETA zeolite [J]. Microporous and Mesoporous Materials, 2005, 79(1/2/3): 145-163.
[9] Lu C, Du X D, Yao X L, et al. Study on breakthrough curves of industrial hexane in fixed-bed absorber containing 5A molecular sieves[J]. Natural Gas Chemical Industry, 2010, 35(3): 30-34; 46.(in Chinese)
[10] Cui Q, Liu Z J, Du X D, et al. Process for producing n-heptane and n-octane simultaneously by pressure-swing adsorption: China, ZL200710133497.4 [P]. 2008-03-05.(in Chinese)
[11] Yao X L, Cui Q, Zhou L J, et al. Pressure-swing adsorption process for extraction of high-purity n-hexane: China, ZL200710133498.9[P]. 2008-03-26.(in Chinese)
[12] Yao X L, Du X D, Liu Z J, et al. Adsorption performance for n-hexane and characterization of 5A molecular sieves[J]. Petrochemical Technology, 2010, 39(7): 757-761.(in Chinese)
[13] Yao X L, Du X D, Liu Z J, et al. Adsorption/desorption and diffusion performance of n-hexane on 5A zeolite at high temperature[J]. Chemical Engineering, 2010, 38(11): 1-4.(in Chinese)
[14] Kang Y F, Du X D, Liu Z J, et al. Adsorption/desorption and diffusion property of n-hexane on 5A molecular sieves under high temperature [J]. Journal of Chemical Engineering of Chinese Universities, 2011, 25(1): 172-176.(in Chinese)
[15] Shams K, Mirmohammadi S J. Preparation of 5A zeolite monolith granular extrudates using kaolin: investigation of the effect of binder on sieving/adsorption properties using a mixture of linear and branched paraffin hydrocarbons [J]. Microporous and Mesoporous Materials, 2007, 106(1/2/3): 268-277.
[16] Chen S Z, Chang K Y, Bai Z L. Study on secondary pore in zeolite molecular sieve materials: Ⅰ. secondary pore in crystalline particle and equivalent diameter of crystalline particle [J]. Journal of East China Institute of Chemical Technology, 1990, 16(6): 611-617.(in Chinese)
[17] Bai Z L, Chen S Z, Chang K Y, et al. Study on secondary pores in zeolite molecular sieve materials: Ⅱ. effect of intracrystalline secondary pores of Y type zeolite on diffusion [J]. Journal of East China Institute of Chemical Technology, 1993, 19(3): 249-254.(in Chinese)
[18] He J, Yan A Z. Studies on properties of 5A molecular sieve for dewaxing processes: Ⅳ. influence of Ca²⁺ exchange degree on desorption and diffusion of n-paraffins in CaNaA molecular sieves [J]. Acta Petrolei Sinica, 1995, 11(3): 13-20.(in Chinese)
[19] Gil A, Gandía L M. Microstructure and quantitative estimation of the micropore-size distribution of an alumina-pillared clay from nitrogen adsorption at 77 K and carbon dioxide adsorption at 273 K [J]. Chemical Engineering Science, 2003, 58: 3059-3075.
[20] Ruthven D M. Principles of adsorption and adsorption processes [M]. New York: Wiley, 1984.
[21] Karger J, Ruthven D M. Diffusion in zeolites and other microporous solids [M]. New York: Wiley, 1992.

Memo

Memo:

Biographies: Du Xudong(1984—), male, graduate; Cui Qun(corresponding author), female, doctor, professor, cuiqun@njut.edu.cn.
Foundation item: The National Natural Science Foundation of China(No. 20876074).
Citation: Du Xudong, Liu Zongjian, Cui Qun, et al. Effect of secondary pore distribution on adsorption diffusion performance of n-hexane on 5A zeolite pellets[J].Journal of Southeast University(English Edition), 2011, 27(3):284-289.[doi:10.3969/j.issn.1003-7985.2011.03.012]

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