四通道中空纤维NaA分子筛内膜的制备与表征

doi:10.15541/jim20170174

摘要/Abstract

摘要：

采用错流真空抽吸涂晶与动态水热合成的方法在四通道陶瓷中空纤维载体的内表面制备出高性能的NaA分子筛膜, 并用于75℃下90wt%乙醇/水混合物渗透汽化脱水分离, 系统考察了晶种液流速、涂晶时间与合成温度对NaA分子筛膜形貌与分离性能的影响。结果表明, 当晶种液流速为100 mL/h、涂晶时间为5 s时制备的NaA分子筛膜致密均匀; 晶种液流速过慢或者涂晶时间过长会导致膜厚增加同时也会在膜表面产生缺陷。当膜在100℃下水热合成两次, 制备的NaA分子筛膜分离性能最佳, 此时膜的分离因子为1585, 通量高达8.8 kg/(m²•h)。当合成温度过低时, 膜的晶化程度较低, 膜表面出现缺陷; 当合成温度过高时, 膜晶体生长速率过快, 交互生长程度较差, 膜的断面产生缺陷, 导致膜分离性能较低。

关键词: 四通道中空纤维, NaA分子筛膜, 内膜, 渗透汽化

Abstract:

High-performance NaA zeolite membranes were prepared on inner-surface of four-channel ceramic hollow fibers by combined counter-diffusion vacuum seeding and dynamic hydrothermal synthesis method. The as-prepared membranes were adopted to the pervaporation dehydration of 90wt% ethanol/water mixture at 75℃. Effects of seeding and synthesis conditions on morphology and separation performance of the membranes were extensively investigated in terms of flow rate of seed suspension, seeding time and synthesis temperature. These results showed that dense and uniform NaA zeolite membrane was obtained when the flow rate of seed suspension was 100 mL/h and the seeding time was 5 s. Over slow flow rate of seed suspension or too long seeding time increased the membrane thickness but generated defects on membrane surface simultaneously. When the NaA zeolite membrane was hydrothermally synthesized at 100℃ for twice, the membrane achieved the best water/ethanol separation factor of 1585 while the permeation flux was 8.8 kg/(m²·h) in the pervaporation dehydration. Lower synthesis temperature led to incomplete membrane crystallization and some defects were observed on the membrane surface. With excessive synthesis temperature defects were also detected in the cross-section of the membrane due to the over rapid crystallite rate, which resulted in poor separation performance of the membrane.

Key words: four-channel hollow fiber, NaA zeolite membrane, inner membrane, pervaporation

中图分类号:

TQ028

王晓磊, 张玉亭, 高冰, 张春, 顾学红. 四通道中空纤维NaA分子筛内膜的制备与表征[J]. 无机材料学报, 2018, 33(3): 339-344.

WANG Xiao-Lei, ZHANG Yu-Ting, GAO Bing, ZHANG Chun, GU Xue-Hong. Preparation and Characterization of NaA Zeolite Membranes on Inner-surface of Four-channel Ceramic Hollow Fibers[J]. Journal of Inorganic Materials, 2018, 33(3): 339-344.

图/表 10

图1 错流真空抽吸涂晶示意图

Fig. 1 Schematic diagram of counter-diffusion vacuum seeding

图2 动态水热合成示意图

Fig. 2 Schematic diagram of dynamic hydrothermal synthesis method

图3 四通道中空纤维断面与内表面的SEM照片

Fig. 3 SEM images of four-channel ceramic hollow fiber(a) Cross-section; (b) Inner-surface

图4 NaA分子筛与分子筛膜的XRD图谱

Fig. 4 XRD patterns of NaA zeolite and zeolite membrane(a) Four-channel ceramic hollow fiber; (b) NaA zeolite; (c) NaA zeolite membrane

图5 不同晶种液流速下合成的NaA分子筛膜表面和断面的SEM照片

Fig. 5 Surface and cross-sectional SEM images of NaA zeolite membranes prepared at different seeds suspension flow rates(a-b) 500 mL/h; (c-d) 300 mL/h; (e-f) 100 mL/h; (g-h) 50 mL/h

表1 不同晶种液流速下合成的NaA分子筛膜渗透汽化性能

Table 1 Pervaporation performance of NaA zeolite membrane prepared at different seeds suspension flow rate

Seeds suspension flow rate/(mL·h^-1)	J/(kg∙m^-2∙h^-1)	α_{water/ethanol}
500	12.5	780
300	10.17	1061
100	8.8	1585
50	12.3	446

图6 不同涂晶时间下合成的NaA分子筛膜表面和断面的SEM照片

Fig. 6 Surface and cross-sectional SEM images of NaA zeolite membrane prepared for different coating periods(a-b) 3 s; (c-d) 5 s; (e-f) 10 s; (g-h) 15 s

表2 不同涂晶时间下合成的NaA分子筛膜渗透汽化性能

Table 2 Pervaporation performance of NaA zeolite membrane prepared for different coating poriod

Coating period/s	J/(kg∙m^-2∙h^-1)	α_{water/ethanol}
3	9.5	133
5	8.8	1585
10	10.4	178
15	9.1	70

图7 不同温度下合成的NaA分子筛膜表面和断面的SEM照片

Fig.7 Surface and cross-sectional SEM images of NaA zeolite membrane prepared at different temperatures(a-b) 95℃; (c-d) 100℃; (e-f) 105℃; (g-h) 110℃

表3 不同温度下合成的NaA分子筛膜渗透汽化性能

Table 3 Pervaporation performance of NaA zeolite membrane prepared at different temperatures

Temperature/℃	J/(kg∙m^-2∙h^-1)	α_{water/ethanol}
95	8.3	273
100	8.8	1585
105	8.0	433
110	9.0	217

参考文献 15

[1]	陈翠仙, 韩宾兵, 朗宁威. 渗透蒸发和蒸汽渗透, 北京: 化学工业出版社, 2004.
[2]	GE Q Q, WANG Z B, YAN Y S.High-performance zeolite NaA membranes on polymer-zeolite composite hollow fiber supports .[J]. Am. Chem. Soc., 2009, 131(47): 17056-17057.
[3]	YU C L, ZHONG C, LIU Y M, et al.Pervaporation dehydration of ethylene glycol by NaA zeolite membranes. Chem. Eng. Res. Des., 2012, 90(9): 1372-1380.
[4]	SHAO J, GE Q Q, SHAN L J, et al.Influences of seeds on the properties of zeolite NaA membranes on alumina hollow fibers. Ind. Eng. Chem. Res., 2011, 50(16): 9718-9726.
[5]	SHAO J, ZHAN Z Y, LI J G, et al.Zeolite NaA membranes supported on alumina hollow fibers: effect of support resistances on pervaporation performance .[J]. Membr. Sci., 2014, 451(1): 10-17.
[6]	SHAN L J, SHAO J, WANG Z B, et al.Preparation of zeolite MFI membranes on alumina hollow fibers with high flux for pervaporation .[J]. Membr. Sci., 2011, 378(1): 319-329.
[7]	XU X C, YANG W S, LIU J, et al.Synthesis of NaA zeolite membrane on a ceramic hollow fiber .[J]. Membr. Sci., 2004, 229(1): 81-85.
[8]	WANG Z B, Ge Q Q, SHAO J, et al.High performance zeolite LTA pervaporation membranes on ceramic hollow fibers by dipcoating-wiping seed deposition .[J]. Am. Chem. Soc., 2009, 131(20): 6910-6911.
[9]	SHI Z Z, ZHANG Y T, CAI C, et al.Preparation and characterization of α-Al2O3 hollow fiber membranes with four-channel configuration. Ceram. Int., 2015, 41(1): 1333-1339.
[10]	LIU D Z, ZHANG Y T, JIANG J, et al.High-performance NaA zeolite membranes supported on four-channel ceramic hollow fibers for ethanol dehydration. RSC Adv., 2015, 5(116): 95866-95871.
[11]	LI B M, LV D, WANG J Q, et al.Synthesis of NaA zeolite membrane on the inner surface of α-Al2O3 tube by dynamic hydrothermal method. Membrane Science Technology, 2005, 25(6): 21-23.
[12]	PERA-TITUS M, MALLADA R, LLORENS J, et al.Preparation of inner-side tubular zeolite NaA membranes in a semi-continuous synthesis system .[J]. Membr. Sci., 2006, 278(1): 401-409.
[13]	PERA-TITUS M, LLORENS J, CUNILL F, et al.Preparation of zeolite NaA membranes on the inner side of tubular supports by means of a controlled seeding technique. Catal. Today, 2005, 104(2): 281-287.
[14]	HUANG A S, LIN Y S, YANG W S.Synthesis and properties of A-type zeolite membranes by secondary growth method with vacuum seeding .[J]. Membr. Sci., 2004, 245(1): 41-51.
[15]	YANG Z Z, LIU Y M, GU X H, et al.Synthesis and characterization of NaA zeolite membranes on inner side of tubular supports. CIESC, 2011, 62(3): 840-845.