Rapid Synthesis and Catalytic Application of B-EU-1/ZSM-5 Composite Zeolite Based on Dual Template

doi:10.15541/jim20150363

Abstract

Abstract:

B-ZSM-5/EU-1 composite zeolite was synthesized with different hydroxides as alkaline materials. It was found that guiding role of sodium was the strongest by comparing structure-directing effect and appearance characteristics. The surface of B-ZSM-5/EU-1 composite zeolite was smooth without obvious crystal limits. The synthetic samples were investigated by TG-DTG, N₂ adsorption-desorption and NH₃-TPD. The results show that the template weight loss rate of dual-mode-one-step composite zeolite is 5.67% , which is lower than that of mechanical composite zeolite (7.31%). The specific surface area, pore volume and microporous average pore size have significantly enlarged, meanwhile the amount and strength of acid have also increased, which will be favorable for the aromatization trend of methanol and the priority diffusion of xylene from the composite zeolite. The performance of the composite zeolite catalyst was evaluated in conversion of methanol to xylene. The results show that the selectivity of aromatics in the oil phase reaches 66.72% by using a dual-mode composite zeolite as a catalyst, of xylene in the aromatics reaches 46.15%, and of p-xylene in the xylene reaches 30.75%. The above results can be attributed to special pore structure for the catalytic reaction, which benefits for the priority diffusion of xylene with a smaller particle size from the B-EU-1/ZSM-5 zeolite.

Key words: dual-template, one-step-method, B-EU-1/ZSM-5, composite zeolite, acidity, porous structure

CLC Number:

O643
TQ426

YANG Dong-Hua, LI Jian-Hua, WANG Xin-Bo, GUO Chao, LV Ai-Ning, DONG Mei, Li Xiao-Feng, DOU Tao. Rapid Synthesis and Catalytic Application of B-EU-1/ZSM-5 Composite Zeolite Based on Dual Template[J]. Journal of Inorganic Materials, 2016, 31(3): 248-256.

Figures/Tables 9

Fig. 1 XRD patterns of the samples synthesized in presence of Li+(A), Na+(B) and K+(C)(n(MOH)/n(SiO2): (a) 0.25; (b) 0.3; (c) 0.5; (d) 1)

Fig. 2 SEM images of B-EU-1/ZSM-5 zeolites samples synthesized by different alkali sources of MOH (LiOH (a), NaOH (b) and KOH (c))

Fig. 3 SEM (a) and TEM (b-d) images of as-synthesized samples B-EU-1/ZSM-5

Fig. 4 N2 adsorption/desorption curves (a) and pore size distributions (b) of composite zeolite samples

Table 1 Pore structure parameters of composite zeolite samples

Zeolite	A_BET/(m²∙g^-1)	V_total/(cm³∙g^-1)	V_micro/(cm³∙g^-1)	D/nm
EU-1	271	0.1914	0.1152	0.6031
ZSM-5	332	0.1908	0.1406	0.5121
B-ZSM-5/EU-1	304	0.1497	0.1029	0.8698

Fig. 5 NH3-TPD profiles of EU-1/ZSM-5 composite zeolite a: Mechanical mixture; b: Dual-template

Fig. 6 TG-DTG curves of EU-1/ZSM-5 mechanical mixture (a) and (b) dual-template

Fig. 7 Distribution of aromatic hydrocarbons in mechanical mixture EU-1/ZSM-5 (a) and B-EU-1/ZSM-5 composite (b)

Fig. 8 Xylene distribution among aromatic hydrocarbon products in mechanical mixture EU-1/ZSM-5 (a) and B-EU-1/ZSM-5 composite (b) zeolite catalysis

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