Directly Synthesis of ZSM-22 Particles by Adding Polyurethane Foam in Ionic Liquid-directed Dry-gel-conversion

doi:10.15541/jim20140575

Abstract

Abstract:

Pure-silica ZSM-22 particles with millimeter size were directly synthesized by adding polyurethane foam (PU foam) in ionic liquid-directed dry-gel-conversion process, where the dry gel was prepared under the unusual acidic condition for hydrolyzing the silica precursor with 1,3-alkylimidazolium ionic liquid as the structure directing agent (SDA). Both the PU foam and the ionic liquid-directed dry-gel-conversion process played essential roles in the formation of macroscopic morphology, because only powder-like sample could be obtained in the absence of foam, and moreover, no such special morphology could be achieved on ZSM-22 zeolite prepared by the PU foam-added traditional hydrothermal synthetic route. Various synthetic parameters were systematically studied, including the influence of PU foam, adding time and adding amount of PU foam, as well as the crystallization time. Pure phase ZSM-22 particles with the highest crystallinity can be obtained by adding appropriate volume of PU foam after microwave aging. Finally, the directly synthesized ZSM-22 particles were modified by impregnating CuO, which exhibited superior N₂O adsorption property to the CuO-impregnated post-molded ZSM-22 particles with binding materials. The results indicate that there is an important influence of the macro-morphology on the adsorption performance of zeolites.

Key words: ZSM-22, macro-morphology control, polyurethane foam, ionic liquid, dry gel conversion, N2O-TPD

CLC Number:

O613

WEN Hai-Meng, SONG Jun, WANG Chong-Qing, ZHOU Yu, WANG Jun. Directly Synthesis of ZSM-22 Particles by Adding Polyurethane Foam in Ionic Liquid-directed Dry-gel-conversion[J]. Journal of Inorganic Materials, 2015, 30(6): 615-620.

Figures/Tables 7

Fig. 1 Macro photographs and SEM images of samples Macro photographs of (a) dry gel, (b) as-synthesized ZSM-22 particles, (c) as-calcined ZSM-22 particles, (d) product synthesized by dry gel conversion without PU foam; (e, f) SEM images of as-calcined ZSM- 22 particles

Fig. 2 XRD patterns and picture (inset) of product synthesized by hydrothermal synthesis method

Fig. 3 XRD patterns of as-calcined ZSM-22 particles synthesized under different conditions (A) With different volumes of PU foam: (a) 2 cm3; (b) 4 cm3; (c) 8 cm3; (B) Adding the PU foam (a) before hydrolysis of TEOS, (b) before aging with microwave; (C) With 16 cm3 PU foam and different crystallization time: (a) 1 d, (b) 2 d, (c) 3 d

Fig. 4 SEM images of as-calcined ZSM-22 particles crystallized at 170℃ for (a) 1 d and (b) 2 d

Fig. 5 (A) N2 adsorption-desorption isotherm of as-calcined ZSM-22 particle synthesized with PU foam of 16 cm3; (B) FT-IR spectra of (a) as-synthesized and (b) as-calcined ZSM-22 particle obtained with PU foam of 16 cm3

Fig. 6 (A) XRD patterns and (B) N2 adsorption-desorption isotherm of the CuO/ZSM-22 particles

Fig. 7 N2O-TPD curves of CuO/ZSM-22 particles

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