Partic. vol. 33 pp. 55-62 (August 2017)
doi: 10.1016/j.partic.2017.01.002

Self-assembly of fibrous ZSM-5 zeolites in the presence of sodium alginate

Jinlong Jiang^a,b,c,*, Shoupeng Ji^a, Chuansong Duanmu^b, Yichang Pan^c, Jie Wu^a, Mei Wu^a, Jing Chen^a

jiangjinlong75@163.com

Abstract

ZSM-5 zeolites with a fibrous morphology were successfully self-assembled in the presence of sodium alginate. The effect of the sodium alginate concentration, Si/Al molar ratio in the synthesis gel, crystallization temperature and time, and the addition order of the sodium alginate on the morphology of the ZSM-5 zeolites was investigated. The possible formation mechanism of fibrous ZSM-5 zeolite crystals was also proposed. The results indicated that the carboxyl and hydroxyl groups of sodium alginate synergistically induced the self-stacking of ZSM-5 nanocrystals and thus the formation of the fibrous ZSM-5 zeolites. The Si/Al molar ratio of the fibrous ZSM-5 zeolites could be adjusted by controlling the amount of the NaAlO₂ additive; however, high Si/Al molar ratios also hindered the self-stacking of ZSM-5 nanocrystals. A high crystallization temperature (180 °C), a moderate sodium alginate concentration (8.33 g/L), and the addition of sodium alginate prior to tetraethoxysilane were necessary for the formation of fibrous ZSM-5 zeolites.

Graphical abstract

Keywords

Fibrous morphology; Self-assembly; Sodium alginate; ZSM-5 zeolite