Preparation and Characterization of Macroporous Mayenite Monoliths

doi:10.15541/jim20140323

Abstract

Abstract:

Macroporous mayenite monoliths were successfully prepared via Sol-Gel process accompanied by phase separation using calcium chloride dihydrate and aluminum chloride hexahydrate as raw materials, propylene oxide (PO) as a gelation agent, and poly (ethylene oxide) with average molecular weight of 100,000 as a phase separation inducer. In addition, glycol was used as a chelating agent and formamide as a drying control chemical additive. Macroporous monoliths were characterized by scanning electron microscope(SEM), mercury porosimetry, and X-ray diffraction (XRD). The result shows that the addition of PEO induces phase separation; the amount of PEO and the ratio of ethanol to water have an important effect on porous structure, and monolithic mayenite with co-continuous marcoporous structure is obtained at appropriate addition of PEO and solvent as well as gelation temperature. The dried gels are amorphous, and transform to Ca₁₂Al₁₄O₃₂Cl₂ after heat-treatment at 1000℃ in air, while the co-continuous macropores are retained. The monolith after heat-treatment has narrow pore size distribution of 1-2 μm and porosity of 73.0%. The monoliths before and after heat-treatment possess smooth and dense skeletons.

Key words: macroporous monolith, mayenite, Sol-Gel, phase separation

CLC Number:

TQ174

GUO Xing-Zhong, CAI Xiao-Bo, SONG Jie, YANG Hui. Preparation and Characterization of Macroporous Mayenite Monoliths[J]. Journal of Inorganic Materials, 2015, 30(2): 141-146.

Figures/Tables 8

Table 1 Starting compositions of samples

	(CaCl₂/AlCl₃) /(g·g^-1)	(EtOH/H₂O) /(mL·mL^-1)	EG^a /mL	FA^b /mL	PO^c /mL	PEO^d /g
CA01	1.044 / 2.000	3.00 / 3.00	0.40	0.50	1.50	0
CA02	1.044 / 2.000	3.00 / 3.00	0.40	0.50	1.50	0.100
CA03	1.044 / 2.000	3.00 / 3.00	0.40	0.50	1.50	0.200
CA04	1.044 / 2.000	3.00 / 3.00	0.40	0.50	1.50	0.400
CA05	1.044 / 2.000	3.50 / 2.50	0.40	0.50	1.50	0.200
CA06	1.044 / 2.000	4.00 / 2.00	0.40	0.50	1.50	0.200
CA07	1.044 / 2.000	2.50 / 3.50	0.40	0.50	1.50	0.200
CA08	1.044 / 2.000	2.00 / 4.00	0.40	0.50	1.50	0.200

Fig. 1 SEM images of gels prepared with varied WPEO (a) 0; (b) 0.100 g; (c) 0.200 g; (d) 0.400 g

Fig. 2 SEM images of dried gels prepared with high volume ratios of ethanol to water (a) 1/1, (b) 7/5, (c) 2/1. Time inserted each image indicates the length of gelation time

Fig. 3 SEM images of dried gels prepared with low volume ratios of ethanol to water (a) 1/1, (b) 5/7, (c) 1/2. Time inserted each image indicates the length of gelation time

Fig. 4 SEM images of dried gels prepared at different gelation temperatures (a) 20℃; (b) 40℃; (c) 60℃; (d) 80℃

Fig. 5 XRD patterns of sample CA03 before and after heat-treated at 1000℃

Fig. 6 Appearance of sample CA03 (a) before and (b) after heat-treatment at 1000℃; (c) SEM image of sample CA03 after heat-treatment at 1000℃

Fig. 7 Macropore size distribution of sample CA03 before and after heat-treatment at 1000℃

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