Economically and eco-friendly synthesis of SSZ-13 zeolite using choline chloride as template with the investigation effects of sodium ion and aging

• Published in: Journal of solid state chemistry 2025-05, Vol.345, p.125216, Article 125216
• Main Authors: Chen, Ze, Li, Yuping, Ji, Fuchao, Liang, Xiaohong, Xuan, Haicheng, Han, Lina, Han, Peide
• Format: Article
• Language: English
• Subjects: Aging; Choline chloride; NH3-SCR of NOx; Sodium ion; SSZ-13 zeolite
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2025.125216

Economical and efficient synthesis of small-size SSZ-13 zeolite catalysts with CHA topology is attractive for reducing the nitrogen oxide (NOx) emissions from diesel vehicles. Herein, SSZ-13 zeolites were prepared using low-cost and environmental-friendly choline chloride (CC) as a template. The effects of additional sodium ions and dynamic stirring aging on the crystallization quality, solid yield and physicochemical properties of the obtained SSZ-13 were investigated by XRD, FT-IR, SEM, N2 sorption and TG-DTG techniques. The results show that three sodium salts (NaCl, NaF, and Na2SO4) and aging steps can improve the relative crystallinity and solid yield of the SSZ-13 zeolites to a certain extent. Meanwhile, it was found that sodium salt and aging process significantly changed the crystal morphology of SSZ-13 zeolite from irregular particle aggregates to regular and uniform cubic crystals. And the crystal size of obtained SSZ-13 zeolites also decreased from ∼3 μm to 250–400 nm (adding sodium salts) or ∼700 nm (adding aging steps), respectively. The decrease in the size of SSZ-13 crystals is mainly attributed to that the addition of additional sodium salts or aging steps promoted the formation of more CHA zeolite nuclei. Additionally, the influence of the Na+(NaF) content and aging time on the synthesis of SSZ-13 were explored, and the effect mechanism of additional sodium ions and aging steps in the current synthetic system were also discussed. Finally, the obtained Cu-SSZ-13 samples after Cu2+ exchange exhibits good catalytic performance for NH3-SCR of NOx reaction, and the NOx conversion remained over 90 % across a temperature window from ∼200 to ∼500 °C, demonstrating its application potentials in diesel vehicle exhausts purification. The introduction of sodium salt and aging steps into the initial gel should promote the formation of more CHA zeolite nuclei, thus effectively preparing submicron SSZ-13 zeolites. When sodium salt is added to the sol, the free Na+ will be adsorbed on the surface of colloidal particles, and the negative charge caused by the initial strong alkaline solution will be neutralized, and the repulsive force between colloidal particles will be reduced, leading to the aggregation of colloidal particles, thus producing more crystal nuclei. Aging promotes nucleation, which can be attributed to its promotion of dissolution and hydrolysis of amorphous silica and aluminum sources in alkaline system, and subsequent condensation into act