Preparation and Characterization of Cyano-functionalized Mesoporous Silica

doi:10.3724/SP.J.1077.2012.00134

Abstract

Abstract:

Cyano-functionalized mesoporous silicas were synthesized by one-pot co-condensation of tetraethoxysilane (TEOS) and 2-cyanoethyltriethoxysilane (CTES), using Pluronic P123 triblock copolymer as the structure- directing agent under strongly acidic conditions. The physicochemical properties, such as structure, morphology, pore property and cyano content were characterized by XRD, SEM, N₂ adsorption-desorption isotherm, FT-IR and elemental analysis, respectively. It was found that the order for adding the two silicon sources, namely CTES and TEOS has a profound influence on the content and distribution of cyano group. Within three mixture orders, the sample synthesized with pre-mixed TEOS and CTES as silica sources is best, with highest cyano content and uniform distribution. As cyano content increasing, surface morphology and pore properties are changed. The straight cylindrical pore structure is transformed into bottle-neck-like structure with up to 20mol% CTES loading in the synthesis mixture. Pore volume, surface area and pore size decrease from 0.70 cm³/g to 0.22 cm³/g, 666 m²/g to 312 m²/g, 4.2 nm to 2.7 nm, respectively when cyano content is increased, which maybe result from that cyano group occupies part of pore channel.

Key words: mesoporous, silica, functionalization, cyano

CLC Number:

O613
TB332

GUO Feng, ZHU Gui-Ru, GAO Cong-Jie. Preparation and Characterization of Cyano-functionalized Mesoporous Silica[J]. Journal of Inorganic Materials, 2012, 27(2): 134-138.

Figures/Tables 7

Table 1 Elemental analysis of cyano-functionalized silica samples prepared by different addition way of silanes

Samples	C content/(mg·g^-1)	N content/(mg·g^-1)	CN content/(mmol·g^-1)	Average CN content/(mmol·g^-1)
M-20/CN	133.7	30.5	2.18	2.19
	124.5	31.3	2.23
	124.9	30.2	2.16
C-20/CN	197.4	42.8	3.06	2.09
	83.8	17.6	1.26
	122.9	27.4	1.96
T-20/CN	144.8	26.2	1.87	1.95
	131.3	27.3	1.95
	123.0	28.3	2.02

Fig. 1 FT-IR spectra of cyano-functionalized mesoporous silicas

Fig. 2 N2 adsorption-desorption isotherms at 77K (A) and pore size distributions curves (B) of cyano-functionalized mesoporous silicas

Table 2 Physicochemical properties of cyano-functionalized mesoporous silicas

Samples	S_BET/(m²·g^-1)*	V_p /(cm³·g^-1)	D_BJH/nm**	C /(mmol·g^-1)	CN content/(mmol·g^-1)	CN /(groups·nm^-2)
M-10/CN	666	0.70	4.22	8.5	1.16	1.05
M-20/CN	533	0.39	3.00	10.7	2.33	2.63
M-30/CN	436	0.29	2.79	13.7	3.34	4.61
M-40/CN	312	0.22	2.68	16.0	4.30	8.30

Fig. 3 XRD patterns of cyano-functionalized mesoporous silicas

Fig. 4 SEM images of mesoporous silica modified with different concentrations of cyano groups

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