Preparation and catalytic study of Mn-NaX, Cu-NaX and Ag-/AgNPs-NaX zeolites

Zeolites are crystalline aluminosilicates with uniform pores, cavities and channels and find application in various industries due to their catalytic, sorption and ion exchange properties [1]. The hydrothermal synthesis is perspective method for obtaining of zeolites [2].

FAU-type zeolite NaX was successfully obtained using hydrothermal synthesis at 90^oC for 6 hours. The Mn and Cu ion exchanged NaX zeolites were obtained using 0.4M MnCl₂ and 0.1M CuCl₂ solutions. After the ion exchange the zeolite powders were thermally treated at 300^oC. As well as Ag ion exchanged zeolite NaX and zeolite impregnated with two types of Ag nanoparticles dispersions – citrate surface stabilized (citAg) and polymer stabilized (pAg) nanoparticles. Silver nanoparticles were synthesized by electrochemical reduction method. The changes in phase and chemical composition and structure of obtained zeolite powders before and after ion exchange or impregnation were investigated by Powder X-ray analysis, Infrared spectroscopy and X-ray fluorescence (XRF) analysis. The XRF results determined that NaX zeolite; Mn, Cu, Ag ion exchanged and impregnated with two types Ag nanoparticles zeolite have the elemental composition: Na (16.49; 2.24; 2.48; 11.37; 12.44; 15.54), Al (29.22; 24.80; 23.46; 23.67; 29.08; 28.99), Si (53.91; 40.18; 33.44; 38.04; 57.51; 54.66), Mn (32.67), Cu (34.13), Ag (26.85; 0.53; 0.53) mass%, respectively. The catalytic ability of the prepared Mn, Cu-exchanged NaX and Ag nanoparticles impregnated zeolites were tested in the reaction of ozone decomposition. The results show that Mn, Cu-exchanged NaX and impregnated with Ag demonstrated catalytic ability towards ozone decomposition in comparison with pure zeolite (non-catalytic activity).

References

[1] S. Chandrasekhar, P.N. Pramada, Sintering behaviour of ammonium exchanged low silica zeolites synthesised by two different routes, Ceramics International 27 (3) (2001) 351-361.

[2] C.S. Cundy, P.A. Cox, The Hydrothermal Synthesis of Zeolites: History and Development from the Earliest Days to the Present Time, Chem. Rev., 103 (2003) 663-701.