Effect of silicon source on synthesis and physicochemical properties of MCM-22 zeolite
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摘要: 在动态水热条件下,研究了硅溶胶、白炭黑、硅酸及硅胶为硅源时对MCM-22分子筛合成及物化性质的影响。以硅溶胶、白炭黑、硅酸三种硅源均可合成出高结晶度且无杂晶的片状MCM-22分子筛,其平均粒径分别为190、220和750 nm。硅源影响分子筛的聚集形态,三种硅源分别形成晶粒分散、晶粒半分散及晶粒聚集形态。三组样品的酸强度分布基本一致,都具有较多的中强酸分布,由硅溶胶和硅酸所得MCM-22分子筛在中强酸范围具有更高的B/L酸比值,以白炭黑合成的分子筛总酸量最高。NMR结果表明,样品中的铝以骨架铝为主,不存在明显的非骨架铝。由于硅胶对合成体系中游离水的吸附作用,水热反应难以发生,不能得到MCM-22分子筛,硅胶作为分子筛合成硅源时需要选择合适的反应条件。Abstract: The effects of silicon source on the synthesis and physicochemical properties of MCM-22 zeolite were studied by using silica sol, fumed silica, silicic acid and silica gel as synthesis materials under dynamic hydrothermal conditions. MCM-22 zeolite with high crytallinity and purity was synthesized by using silica sol, silica, silicic acid and silica gel as silicon sources. The average sizes of zeolite particle are 190, 220 and 750 nm, respectively. Three silicon sources can affect the aggregate morphology of the zeolites, which are grain dispersion, grain semi dispersion and grain aggregation. The distribution of acid strength of the three groups of samples are almost same, all of them have more medium and strong acidity, and the total acid content of zeolite synthesized by fumed silica is the highest. MCM-22 obtained from silica sol and silicic acid has higher B/L acid ratios in the range of medium strong acid. The results of NMR show that the main aluminum in the samples is skeleton aluminum without obvious non-skeleton aluminum. MCM-22 zeolite can not be obtained when silica gel is used as silicon source because silica gel can adsorb the free water in the preparation system, suppressing the hydrothermal reaction. The reaction conditions should be carefully set up when silica gel is used as silicon source to prepare zeolite.
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Key words:
- silica sol /
- fumed silica /
- silicic acid /
- zeolite /
- MCM-22
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表 1 不同硅源合成的MCM-22分子筛的比表面积和孔容
Table 1 Surface area and pore volume of the MCM-22 synthesized using different silicon sources
Silicon source Product Size d/nm Specific surface area S/(m2·g-1) Pore volume v/(mL·g-1) Stotal Sinner Souter vmicropore vtotal Sillica sol MCM-22 190 562 408 154 0.179 0.435 Fumed sillica MCM-22 220 522 395 127 0.180 0.455 Silicic acid MCM-22 750 486 377 109 0.174 0.478 表 2 不同硅源合成的MCM-22分子筛的SiO2/Al2O3比及样品收率
Table 2 SiO2/Al2O3 ratios of the MCM-22 synthesized using different silicon sources
Silicon source Feed Sillica sol Fumed sillica Silica gel SiO2/Al2O3 30 24.5 25.2 25.7 Yield w/% 71.4 69.7 70.3 表 3 由不同硅源合成样品的酸强度分布
Table 3 Acid strength distribution of the samples synthesized using different silicon sources
Acid strength
distributionMCM-22
by silica solMCM-22
by fumed silicaMCM-22
by silicic acidcontent B/L content B/L content B/L Total acid(160℃)/(mmol·g-1) 0.95 2.92 1.10 1.99 0.91 3.27 160-250℃(weak acid) 19.4% 1.14 18.3% 0.71 17.4% 2.18 250-450℃(medium acid) 37.6% 6.25 36.1% 1.58 38.2% 5.33 450℃(strong acid) 43.0% 2.96 45.6% 4.17 44.40% 2.71 -
[1] 韩文雯, 王清涛, 张群峰, 吕井辉, 李小年. MCM-22分子筛催化烷基化反应的研究进展[J].现代化工, 2017, 37(10): 20-24. http://www.cnki.com.cn/Article/CJFDTotal-XDHG201710005.htmHAN Wen-wen, WANG Qin-tao, LV Jing-hui, LI Xiao-nian. Research progress of MCM-22 molecular sieve in alkylation[J]. Mod Chem Ind, 2017, 37(10): 20-24. http://www.cnki.com.cn/Article/CJFDTotal-XDHG201710005.htm [2] 李丹, 耿南坤, 詹珂, 闵慧, 周丹, 夏清华.分级结构MCM-22分子筛高效催化α-蒎烯异构化[J].湖北大学学报(自然科学版), 2017, 39(4):405-410. doi: 10.3969/j.issn.1000-2375.2017.04.013LI Dan, GENG Nan-kun, ZHAN Ke, MING Hui, ZHOU Dan, XIA Qing-hua. Hierarchical MCM-22 as an efficient catalyst for the isomerization of α-pinene[J]. J Hubei Univ (Nat Sci), 2017, 39(4):405-410. doi: 10.3969/j.issn.1000-2375.2017.04.013 [3] YANG J, CHU J, WANG J, YIN D, LU J, ZHANG Y. Synthesis and catalytic performance of hierarchical MCM-22 zeolite aggregates with the assistance of carbon particles and fluoride ions[J]. Chin J Catal, 2014, 35(1):49-57. https://www.sciencedirect.com/science/article/pii/S1872206712607116 [4] DOS SANTOS M B, ANDRADE H M C, MASCARENHAS A J S. Oxidative dehydration of glycerol over alternative H, Fe-MCM-22 catalysts:Sustainable production of acrylic acid[J]. Microporous Mesoporous Mater, 2019, 278:366-377. https://www.sciencedirect.com/science/article/abs/pii/S1387181119300162 [5] WANG C, WANG Y, XIE Z. Understanding zeolites catalyzed methanol-to-olefins conversion from theoretical calculations[J]. Chin J Chem, 2018, 36(5):381-386. doi: 10.1002/cjoc.201800040 [6] RUTKOWSKA M, DÍAZ U, PALOMARES A E, CHMIELARZ L. Cu and Fe modified derivatives of 2D MWW-type zeolites (MCM-22, ITQ-2 and MCM-36) as new catalysts for DeNOx process[J]. Appl Catal B:Environ, 2015, 168-169:531-539. doi: 10.1016/j.apcatb.2015.01.016 [7] 王振东, 刘闯, 孙洪敏, 沈震浩, 杨为民.不同有机结构导向剂合成MCM-22分子筛及其催化性能[J].石油化工, 2020, 49(3):209-213. doi: 10.3969/j.issn.1000-8144.2020.03.001WANG Zhen-dong, LIU Chuang, SUN Hong-min, SHEN Zhen-hao, YANG Wei-min. MCM-22 zeolites synthesized with different organic structure-directing agents and catalytic performances[J]. Petrochem Technol, 2020, 49(3):209-213. doi: 10.3969/j.issn.1000-8144.2020.03.001 [8] 王保玉.晶种对MCM-22分子筛合成的影响[J].洛阳师范学院学报, 2016, 35(11):29-31. http://www.cnki.com.cn/Article/CJFDTOTAL-LSZB201611010.htmWANG Bao-yu. The influences of various crystal seeds on the synthesis of MCM-22 molecular sieve[J]. J Luoyang Normal Univ, 2016, 35(11):29-31. http://www.cnki.com.cn/Article/CJFDTOTAL-LSZB201611010.htm [9] TEMPELMAN C H L, PORTILLA M T, MARTíNEZ-ARMERO M E, MEZARI B, DE CALUWÉ N G R, MARTÍNEZ C, HENSEN E J M. One-pot synthesis of nano-crystalline MCM-22[J]. Microporous Mesoporous Mater, 2016, 220:28-38. doi: 10.1016/j.micromeso.2015.08.018 [10] 任花萍, 田少鹏, 马强, 丁思懿, 李小利, 高健.一种以凹凸棒土为原料合成MCM-22分子筛的方法: 中国, 106517235B[P]. 2019-02-19.REN Hua-ping, TIAN Shao-peng, MA Qiang, DING Si-yi, LI Xiao-li, GAO Jian. Synthesis of MCM-22 molecular sieve from Attapulgite: CN, 106517235B[P]. 2019-02-19. [11] OGURA M, INOUE K, YAMAGUCHI T. A mechanistic study on the synthesis of MCM-22 from SBA-15 by dry gel conversion to form a micro-and mesoporous composite[J]. Catal Today, 2011, 168(1):118-123. doi: 10.1016/j.cattod.2010.12.046 [12] DOS SANTOS E R F, SOUSA A B, LEITE R C N, LABORDE H M, MENEZES R R, FREIRE RODRIGUES M G. Preparation of zeolite MCM-22 using the rice husk ash as silica source[J]. Mater Sci Forum, 2014, 805:646-650. doi: 10.4028/www.scientific.net/MSF.805.646 [13] CHENG Y, LU M, LI J, SU X, PAN S, JIAO C, FENG M. Synthesis of MCM-22 zeolite using rice husk as a silica source under varying-temperature conditions[J]. J Colloid Interface Sci, 2012, 369(1):388-394. doi: 10.1016/j.jcis.2011.12.024 [14] THAKKAR R, BANDYOPADHYAY R. Preparation, characterization, and post-synthetic modification of layered MCM-22 zeolite precursor[J]. J Chem Sci, 2017, 129(11):1671-1676. doi: 10.1007/s12039-017-1366-3 [15] 朱夔, 李杨, 刘汉文, 贾继伟, 孙树明, 刘志刚.白炭黑在ZSM-5分子筛工业合成中的应用[J].工业催化, 2018, 26(5):151-154. doi: 10.3969/j.issn.1008-1143.2018.05.025ZHU Kui, LI Yang, LIU Han-wen, JIA Ji-wei, SUN Shu-ming, LIU Zhi-gang. Application of white carbon black in ZSM-5 molecular sieve industrial synthesis[J]. Ind Catal, 2018, 26(5):151-154. doi: 10.3969/j.issn.1008-1143.2018.05.025 [16] 张佩珊, 马波, 杨卫亚, 凌凤香, 沈智奇, 王少军, 候宇鑫.核壳结构Beta/MCM-22双微孔复合分子筛的合成与表征[J].燃料化学学报, 2014, 42(10):1240-1245. doi: 10.3969/j.issn.0253-2409.2014.10.013ZHANG Pei-shan, MA Bo, YANG Wei-ya, LING Feng-xiang, SHEN Zhi-qi, WANG Shao-jun, HOU Yu-xin. Synthesis and characterization of core-shell Beta/MCM-22 micro-microporous composite zeolites[J]. J Fuel Chem Technol, 2014, 42(10):1240-1245. doi: 10.3969/j.issn.0253-2409.2014.10.013 [17] 杨若晨, 马波, 凌凤香, 杨卫亚, 沈智奇, 王磊. MCM-22分子筛的高效合成与表征[J].石油化工, 2012, 41(1):19-21. http://d.wanfangdata.com.cn/periodical/syhg201201003YANG Ruo-chen, MA Bo, LING Feng-xiang, YANG Wei-ya, SHEN Zhi-qi, WANG Lei. Synthesis and characterization of zeolite MCM-22[J]. Petrochem Technol, 2012, 41(1):19-21. http://d.wanfangdata.com.cn/periodical/syhg201201003 [18] CORMA A, DIAZ U, FORNÉS V, GUIL J M, MARTÍNEZ-TRIGUERO J, CREYGHTON E J. Characterization and catalytic activity of MCM-22 and MCM-56 compared with ITQ-2[J]. J Catal, 2000, 191(1):218-224. https://www.academia.edu/8476092/Characterization_and_Catalytic_Activity_of_MCM-22_and_MCM-56_Compared_with_ITQ-2 [19] 喻志武, 王强, 陈雷, 邓风. H-MCM-22沸石分子筛中Brønsted/Lewis酸协同效应的1H和27Al双量子魔角旋转固体核磁共振研究[J].催化学报, 2012, 33(1):2140-2150. http://www.cqvip.com/QK/93027X/201201/40860857.htmlYU Zhi-wu, WANG Qiang, CHEN Lei, DENG Feng. Brønsted/Lewis acid sites synergy in H-MCM-22 zeolite studied by 1H and 27Al DQ-MAS NMR spectroscopy[J]. Chin J Catal, 2012, 33(1):2140-2150. http://www.cqvip.com/QK/93027X/201201/40860857.html [20] VAN MILTENBURG A, PAWLESA J, BOUZGA A M, ČCEJKA J, ST CKER M. 27Al and 29Si MAS-NMR study of the MCM-22 zeolite modified by steam and alkaline treatments[C]. Studies in Surface Science and Catalysis, 2008, 174: 937-940. [21] 陈雷, 邓风, 叶朝辉.铝在MCM-22分子筛骨架上分布的27Al MQ MAS NMR研究[J].物理化学学报, 2003, 19(9):805-809. doi: 10.3866/PKU.WHXB20030905CHEN Lei, DENG Feng, YE Zhao-hui. 27Al MultiPle Quantum MAS NMR study on the ditribution of aluminium in the zeolite MCM-22[J]. Acta Phys-Chim Sin, 2003, 19(9):805-809. doi: 10.3866/PKU.WHXB20030905 [22] CUNDY C S, COX P A. The hydrothermal synthesis of zeolites:Precursors, intermediates and reaction mechanism[J]. Microporous Mesoporous Mater, 2005, 82(1):1-78. https://www.sciencedirect.com/science/article/abs/pii/S1387181105000934