Synthesis and Characterization of ZSM-5/MCM-41 Meso/Microporous Composite Molecular Sieve Incorporated by Lanthanum
-
摘要: 以CTMABr、TPABr为介、微孔模板剂, Na2SiO3为硅源, Al2(SO4)3为铝源, La2O3的H2SO4溶液为La供体, 在水热条件下, 通过La离子导入、预置晶种、二步晶化等手段, 首次合成出La杂原子ZSM-5/MCM-41复合分子筛.XRD、N2吸附脱附结果表明, 样品共存ZSM-5和MCM-41两种物相, 两种结构、孔径在介、微孔范围都有分布, 且La可取代分子筛骨架的少量Si.SEM照片显示, 样品晶粒局部聚集成不规则的团块, 构成团块的颗粒大小不一但结合紧密, 与ZSM-5、MCM-41形貌明显不同.IR曲线中不存在La2O3的特征吸收谱, 样品特征骨架振动峰向高波位移的现象, 以及样品微分热失重峰向高温方向偏移, 加之DTA曲线肩峰的出现进一步说明La杂原子ZSM-5/MCM-41复合分子筛的合成.
-
关键词:
- ZSM-5/MCM-41复合分子筛 /
- 稀土La /
- 合成 /
- 表征
Abstract: A ZSM-5/MCM-41 meso/microporous composite molecular sieve incorporated by lanthanum, noted as La-ZSM-5/MCM-41, was first synthesized under hydrothermal condition using sodium silicate (Na2SiO3) and aluminium sulphate (Al2(SO4)3) as Si and Al sources, sulfurate solution of lanthanum oxide (La2O3) as La supply and cetyltrimethyammonium bromide (CTMABr) and tetrepropylammonium bromide (TPABr) as mesoporous and microporous templates. There are several main procedures performed during the synthetic process, involving the introduction of rare earth La, the addition of ZSM-5 seed crystal and the two-step crystallization. The composite was characterized by means of XRD, N2 adsorption, SEM, IR, TG-DTG and DTA. The results of XRD and N2 adsorption measurement indicate that the synthetic sample possesses a composite phase containing mesoporous MCM-41 structure and microporous ZSM-5 structure, a dual pore structure whose pore size distribution lies respectively in mesoporous and microporous region, and rare earth La can replace Si existing in the framework of the composite sample. SEM micrograph of La-ZSM-5/MCM-41 sample shows the nonuniform agglomerates assembled by many spherical particles of different sizes closely combined with each other, which differ greatly in the morphology from pure ZSM-5 and MCM-41 molecular sieves. Moreover, the characteristic absorbing bands of La2O3 cannot be seen in La-ZSM-5/MCM-41 sample′s IR spectra. In comparison with that of ZSM-5/MCM-41 composite, La-ZSM-5/MCM-41 sample′s main IR vibrational peaks vary to low wavenumber and its weight loss peaks also shift to high temperature as well as a new and light exothermic peak appears in its DTA curve. All these phenomena demonstrate the replacement between Si in the framework of ZSM-5/MCM-41 composite and rare earth La, and prove the successful synthesis of ZSM-5/MCM-41 composite molecular sieve incorporated by rare earth La.-
Key words:
- ZSM-5/MCM-41 composite molecular sieve /
- rare earth La /
- incorporation /
- synthesis
-
图 2 La-ZSM-5/MCM-41的N2吸附脱附等温线(a) 和BJH孔径分布曲线(b)
Fig. 2. N2 adsorption-desorption isotherm (a) and BJH pore size distribution curve (b) of La-ZSM-5/MCM-41 composite molecular sieve
图 3 各分子筛样品的SEM图片
Fig. 3. Scanning electron micrographs of molecular sieve samples
a.MCM-41 (×2 000);b.ZSM-5 (×2 000);c.La-ZSM-5/MCM-41 (×2 000);d.La-ZSM-5/MCM-41 (×6 000)
图 4 分子筛样品的IR图谱
Fig. 4. IR spectra of molecular sieve samples
a.La-ZSM-5/MCM-41;b.ZSM-5/MCM-41
图 5 复合分子筛样品的TG-DTG曲线
Fig. 5. TG-DTG curves for synthetic samples
a.ZSM-5/MCM-41;b.La-ZSM-5/MCM-41
图 6 复合分子筛样品的DTA曲线
Fig. 6. DTA curves for synthetic samples
a.ZSM-5/MCM-41;b.La-ZSM-5/MCM-41
表 1 各分子筛样品的XRD数据及晶胞参数
Table 1. XRD data and structure parameters of molecular sieve samples
表 2 La-ZSM-5/MCM-41复合分子筛样品的孔结构参数
Table 2. Pore structure parameters of La-ZSM-5/MCM-41 composite molecular sieve
-
[1] Araujo, A. S., Jaroniec, M., 1999. Synthesis and property oflanthanide incorporated mesoporous molecular sieve. Journal of Colloid and Interface Science, 218 (2): 462-468. doi: 10.1006/jcis.1999.6437 [2] Beck, J. S., Vartuli, J. C., Roth, W. J., et al., 1992. A newfamily of mesoporous molecular sieves prepared withliquid crystal templates. J. Am. Chem. Soc, 114: 10834-10843. doi: 10.1021/ja00053a020 [3] Besson, E., Mehdi, A., Reye, C., et al., 2007. Functionalisa-tion of the framework of mesoporous organosilicas byrare earth complexes. Journal of Materials Chemistry, 16 (3): 246-248. [4] Gao, Z. X., Cheng, C. R., Tan, C. Y., et al., 1996. Character-ization of Na, NBA-Ga-Si-ZSM-5zeolite. Chinese Jour-nal of Catalysis, 17 (6): 556-561 (in Chinese withEnglish abstract). [5] Gavrilko, T., Gnatyuk, I., Puchkovskaya, G., et al., 2000. Effect of encapsulation in MCM-41-type molecularsieves on vibrational spectra of liquid crystalline state. Vibrational Spectroscopy, 23 (2): 199-206. doi: 10.1016/S0924-2031(00)00060-6 [6] Ge, X. G., Ma, G. W., Huang, S. Y., et al., 2004. Synthesisand characterization of materials La-MCM-41meso-porous molecular sieves with La skeleton adulteration. Chinese Rare Earths, 25 (6): 1-4 (in Chinese with Eng-lish abstract). [7] Ge, X. G., Shi, L., Wei, J. X., et al., 2005. Synthesis andcharacterization of mesoporous materials MCM-41in-corporated by ytrrium, neodymiumand samarium. Jour-nal of Rare Earth, 23 (5): 521-525. [8] Huang, L. M., Guo, W. P., Deng, P., et al., 2000. Investiga-tion of synthesizing MCM-41/ZSM-5composites. J. Phys. Chem. B, 104 (13): 2817-2824. doi: 10.1021/jp990861y [9] Khalil, K., 2007. Cerium modified MCM-41nanocompositematerials via a nonhydrothermal direct method at roomtemperature. Journal of Colloid and Interface Sci-ence, 315 (2): 562-568. doi: 10.1016/j.jcis.2007.07.030 [10] Kresge, C. T., Leonowicz, M. E., Roth, W. J., et al., 1992. Ordered mesoporous molecular sieves synthesized by aliquid crystal template mechanism. Nature, 359 (6397): 710-712. doi: 10.1038/359710a0 [11] Kuang, Y. P., He, N. Y., Wang, J., et al., 2001. Investiga-ting the state of Fe and La in MCM-41mesoporous mo-lecular sieve materials. Colloids and Surfaces A: Phys-icochemical and Engineering, 179 (2-3): 177-186. doi: 10.1016/S0927-7757(00)00654-3 [12] Ma, Z. L., Zhao, T. B., Zong, B. N., 2004. Synthesis, charac-terization and catalytic property of the Co-crystalline ze-olite of ZSM-5and mordenite. Acta Petrolei Sinica (Petroleum Processing Section), 20 (2): 21-25 (inChinese with English abstract). [13] Minachelf, X. M., Hodacolf, I. O., Marcolf, M. A., 1987. Ap-plication of rare earths in catalysis. Science Press, Bei-jing (in Chinese). [14] Shi, L., Ge, X. G., Huang, S. Y., et al., 2005. Synthesis andcharacterization of mesoporous materials MCM-41in-corporated by Y, Nd and Sm. Journal of the ChineseRare Earth Society, 23 (4): 438-443 (in Chinese withEnglish abstract). [15] Xiong, C. R., Tang, M. H., Liu, B. C., et al., 2007. UsingSEMphotos to gain the pore structural parameters ofsoil samples. Earth Science—Journal of China Univer-sity of Geosciences, 32 (3): 415-419 (in Chinese withEnglish abstract). [16] Xu, G. X., 2002. Rare earths. Metallurgical Industry Press, Beijing (in Chinese). [17] Zheng, Y., Qiu, J. B., Chen, Q. H., et al., 2002a. Synthesisand characterization of Pr-MCM-41mesoporous molec-ular sieve. Journal of the Chinese Rare Earth Society, 20 (S2): 16-19 (in Chinese with English abstract). [18] Zheng, Y., Qiu, W. W., Zhang, X. Q., et al., 2002b. Synthe-sis and characterization of (Dy, Mn) MCM-41meso-porous molecular sieve. Journal of the Chinese RareEarth Society, 20 (S1): 130-134 (in Chinese with Eng-lish abstract). [19] 高志贤, 程昌瑞, 谭长瑜, 等, 1996. Na, NBA-Ga-Si-ZSM-5杂原子沸石分子筛的表征. 催化学报, 17 (6): 556-561. https://www.cnki.com.cn/Article/CJFDTOTAL-CHUA201804018.htm [20] 葛学贵, 马广伟, 黄少云, 等, 2004. La骨架负载中孔分子筛的合成与表征. 稀土, 25 (6): 1-4. doi: 10.3969/j.issn.1004-0277.2004.06.001 [21] 马忠林, 赵天波, 宗保宁, 2004. ZSM-5/丝光沸石混晶分子筛的合成、表征及性能研究. 石油学报(石油加工), 20 (2): 21-25. doi: 10.3969/j.issn.1001-8719.2004.02.004 [22] 石磊, 葛学贵, 黄少云, 等, 2005. 钇、钕和钐负载的MCM-41介孔材料的合成和表征. 中国稀土学报, 23 (4): 438-443. doi: 10.3321/j.issn:1000-4343.2005.04.013 [23] 熊承仁, 唐辉明, 刘宝琛, 等, 2007. 利用SEM照片获取土的孔隙结构参数. 地球科学——中国地质大学学报, 32 (3): 415-419. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200703015.htm [24] 徐光宪, 2002. 稀土. 北京: 冶金工业出版社. [25] 郑瑛, 邱健斌, 陈前火, 等, 2002a. Pr-MCM-41介孔分子筛合成与表征. 中国稀土学报, 20 (S2): 16-19. https://www.cnki.com.cn/Article/CJFDTOTAL-XTXB2002S2035.htm [26] 郑瑛, 邱玮玮, 张晓勤, 等, 2002b. (Dy, Mn) MCM-41介孔分子筛的合成与表征. 中国稀土学报, 20 (S1): 130-134. https://www.cnki.com.cn/Article/CJFDTOTAL-XTXB202003011.htm -
下载:
点击查看大图
计量
- 文章访问数: 3287
- HTML全文浏览量: 87
- PDF下载量: 39
- 被引次数: 0
