Synthesis and Characterization of ZSM-5/EU-1 Composite Zeolite with ore-shell Structure by One Step

doi:10.15541/jim20150511

Abstract

Abstract:

ZSM-5/EU-1 core-shell intergrowth composite zeolite was synthesized by one-step crystallization method based on dual-template and appropriate citric acid addition. The properties of core-shell zeolite were characterized by XRD, TEM, FT-IR, NH₃-TPD, etc. The results showed that there were ZSM-5 and EU-1 zeolite crystalline phases formed in the core-shell zeolite, as EU-1 overgrowing around ZSM-5 surface defects. The synthetic sample composed of microporous and mesoporous multiple porous composite zeolite, with micropore diameter of 0.94 nm. The core-shell structure increased strong acid content and improved its acidity as compared with the single zeolite. Based on the investigation of citric acid addition and crystallization time influence on the structure and Zeta potential of core-shell zeolite, the optimum condition of core-shell intergrowth was as follows, i.e. n(citrate)/n(Al₂O₃)=0.8-1.2 and crystallization time of 72-96 h. And the possible growth process of core-shell zeolite was proposed.

Key words: core-shell zeolite, ZSM-5/EU-1, multiple porous, acidity

CLC Number:

O643
TQ426

LI Jian-Hua, YANG Dong-Hua, LV Ai-Ning, MA Cun-Cun, Li Xiao-Feng, DOU Tao. Synthesis and Characterization of ZSM-5/EU-1 Composite Zeolite with ore-shell Structure by One Step[J]. Journal of Inorganic Materials, 2016, 31(5): 492-498.

Figures/Tables 10

Fig. 1 XRD patterns and FT-IR spectra of different zeolites

Fig. 2 SEM images of EU-1 zeolite (a), ZSM-5 zeolite (b), and SEM (c) and different magnifications TEM (d, e, f ) images of core-shell composite zeolite

Fig. 3 Nitrogen adsorption-desorption isotherms pore size distribution of core/shell zeolite

Table 1 Pore structure parameters of different zeolites

Sample	A_BET/(m²·g^-1)	V_total/(cm³∙g^-1)	V_micro/(cm³∙g^-1)	D/nm
EU-1	271.0	0.1914	0.1152	0.6031
ZSM-5	332.0	0.1908	0.1406	0.5121
ZSM-5/EU-1	208.9	0.1313	0.0630	0.9400

Fig. 4 TG-DTG curves of ZSM-5/EU-1 core-shell zeolite

Fig. 5 XRD patterns of core/shell ZSM-5/EU-1 zeolites synthesized with different citric acid additions n(Citrate)/n(Al2O3)=0.6 (a), 0.8 (b), 1.0 (c), 1.2 (d), 1.5 (e)

Fig. 6 Zeta potential and relativity crystallization curves for core/shell ZSM-5/EU-1 zeolites synthesized with different citric acid additions

Fig. 7 SEM(a) and different magnifications TEM(b-e) images of core-shell zeolite

Fig. 8 XRD patterns of core-shell ZSM-5/EU-1 synthesized with different crystallization time a,b,c,d,e,f,g=8 h, 12 h, 24 h, 48 h, 72 h, 96 h, 108 h

Fig. 9 NH3-TPD patterns of H-ZSM-5 (a), H-EU-1 (b), and core/shell ZSM-5/EU-1 zeolite (c)

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