阴阳离子表面活性剂混合模板剂合成介孔MCM-48分子筛
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摘要
采用溶胶-凝胶法,以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和阴离子表面活性剂十二烷基硫酸钠(SDS)混合体系为模板剂,在较大幅度降低模板剂用量(模板剂与硅源的摩尔比从0.55降至0.177)的条件下,合成了高度有序的介孔MCM-48分子筛。为提高分子筛合成的重复性,对影响介孔MCM-48分子筛合成的因素,如水与硅的摩尔比(简称水硅比)、晶化时间及混合模板剂中SDS与CTAB的摩尔比进行了考察。实验结果表明,最佳合成配方中水硅比为62,反应条件为373 K下晶化72 h,混合模板剂中SDS与CTAB的摩尔比为0.164;在此条件下合成的介孔MCM-48分子筛的孔径为2.72 nm,比表面积为861.8 m2/g。
Highly ordered mesoporous MCM-48 molecular sieves was synthesized by sol-gel method using mixed surfactant system consisted of cationic cetyltrimethylammonium bromide(CTAB) and anionic sodium dodecyl sulfate(SDS) as the template at low surfactant-to-silica mole ratio of 0.177.The characterization of the material shows that the pore diameter and BET surface area of the prepared mesoporous MCM-48 molecular sieves are 2.72 nm and 861.8 m2/g,respectively.In order to improve the synthesis repeatability,the effects of main factors on the synthesis were studied.The results show that the suitable mole ratios of SDS/CTAB and H2O/SiO2 are 0.164 and 62,respectively.The optimized crystallization conditions are crystallization time of 72 h and crystallization temperature of 373 K.
Highly ordered mesoporous MCM-48 molecular sieves was synthesized by sol-gel method using mixed surfactant system consisted of cationic cetyltrimethylammonium bromide(CTAB) and anionic sodium dodecyl sulfate(SDS) as the template at low surfactant-to-silica mole ratio of 0.177.The characterization of the material shows that the pore diameter and BET surface area of the prepared mesoporous MCM-48 molecular sieves are 2.72 nm and 861.8 m2/g,respectively.In order to improve the synthesis repeatability,the effects of main factors on the synthesis were studied.The results show that the suitable mole ratios of SDS/CTAB and H2O/SiO2 are 0.164 and 62,respectively.The optimized crystallization conditions are crystallization time of 72 h and crystallization temperature of 373 K.
引文
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[21]Zhao Wei,Li Quanzhi.Synthesis of Nanosize MCM-48 withHigh Thermal Stability[J].Chem Mater,2003,15(22):图7SDS/CTAB作为模板剂合成MCM-48分子筛的可能合成机理Fig.7 Possible synthesis mechanism for MCM-48 molecular sievesusing SDS/CTAB as the template.g:packing parameter;V:total volume of surfactant hydrophobicchains plus any cosolvent between the chains;a0:effectivehydrophilic headgroup area at the aqueous-micelle surface;l:kinetic surfactant tail length.SDSCTABCTAB+SDSa0a0decreaseVlg increaseV increase4160-4162.
[22]Zhao Wei,Li Quanzhi,Wang Lina,et al.Synthesis of HighQuality MCM-48 with Binary Cationic-Nonionic Surfactants[J].Langmuir,2010,26(10):6982-6988.
[23]Maiti K,Mitra D,Mitra R N,et al.Self-Aggregation ofSynthesized Novel Bolaforms and Their Mixtures with So-dium Dodecyl Sufate(SDS)and CetyltrimethylammoniumBromide(CTAB)in Aqueous Medium[J].J Phys Chem B,2010,114(22):7499-7508.
[2]Xu Jie,Luan Zhaohua,He Heyong,etal.A Reliable synthesisof Cubic Mesoporous MCM-48 Molecular sieve[J].ChemMater,1998,10(11):3690-3698.
[3]桑磊,陈胜利,袁桂梅,等.介孔催化剂在烯烃歧化中的研究进展[J].石油化工,2012,41(1):111-116.
[4]王贵珍,陈玉红,李永真,等.介孔SBA-15分子筛对苯酚的吸附性能[J].石油化工,2012,41(6):704-708.
[5]Wan Ying,Zhao Dongyuan.On the Controllable Soft-Templa-ting Approach to Mesoporous Silicates[J].Chem Rev,2007,107(7):2821-2860.
[6]亢宇,张明森,谢伦嘉,等.空心球状介孔硅基材料负载茂金属催化剂及催化乙烯聚合的研究[J].石油化工,2012,41(1):27-32.
[7]刘红梅,张明森,黄文氢,等.Ti-SBA-15介孔分子筛的制备与表征[J].石油化工,2012,41(2):143-149.
[8]Huo Qisheng,Margolese D I,Stucky G D.Surfactant Controlof Phases in the Synthesis of Mesoporous Silica-Based Materi-als[J].Chem Mater,1996,8(5):1147-1160.
[9]Khushalani D,Kuperman A,Ozin G A,et al.Mixed Sur-factant Assemblies in the Synthesis of Mesoporous Silicas[J].Chem Mater,1996,8(8):2188-2193.
[10]颜学武,陈海鹰,李全芝.以混合中性-阳离子表面活性剂为模板合成MCM-48[J].化学学报,1998,56(12):1214-1217.
[11]Ryoo R,Joo S H,Kim J M.Energetically Favored Formationof MCM-48 from Cationic-Neutral Surfactant Mixtures[J].JPhys Chem B,1999,103(35):7435-7440.
[12]Krystyna C,Abdelhamid S.Synthesis of MCM-48 SilicaUsing a Gemini Surfactant with a Rigid Spacer[J].ChemMater,2006,18(17):4147-4150.
[13]刘春艳,荣志红,王小青.以混合阳离子-嵌段共聚物表面活性剂为模板合成介孔MCM-48[J].无机化学学报,2008,24(7):1068-1072.
[14]Wei Fenyan,Liu Zhongwen,Lu Jian,et al.Synthesis ofMesoporous MCM-48 Using Fumed Silica and Mixed Sur-factants[J].Microporous Mesoporous Mater,2010,131(1/3):224-229.
[15]Chen Fengxi,Huang Liming,Li Quanzhi.Synthesis ofMCM-48 Using Mixed Cationic-Anionic Surfactants as Tem-plates[J].Chem Mater,1997,9(12):2685-2686.
[16]Chen Fengxi,Yan Xuewu,Li Quanzhi.Effect of Hydro-thermal Conditions on the Synthesis of Siliceous MCM-48 inMixed Cationic-Anionic Surfactants Systems[J].Stud Surf SciCatal,1998,117:273-280.
[17]Chen Fengxi,Song Fubing,Li Quanzhi.Mixed Cationic-Anionic Templating Route to Al-MCM-48[J].MicroporousMesoporous Mater,1999,29(3):305-310.
[18]Chandra D,Bhaumik A.Highly Active 2D Hexagonal Meso-poous Titanium Silicate Synthesized Using a Cationic AnionicMixed-Surfactant Assembly[J].Ind Eng Chem Res,2006,45(14):4879-4883.
[19]Wang Jingjing,Lu Jinming,Wang Jinqu,et al.Synthesis ofOrdered MCM-48 by Introducing Economical Anionic Surfac-tant as Co-Template[J].Mater Lett,2012,78:199-201.
[20]王海波,张粟,王静静,等.SDS/CTAB/H2O体系特异性质研究[J].化学研究与应用,2007,19(8):855-857.
[21]Zhao Wei,Li Quanzhi.Synthesis of Nanosize MCM-48 withHigh Thermal Stability[J].Chem Mater,2003,15(22):图7SDS/CTAB作为模板剂合成MCM-48分子筛的可能合成机理Fig.7 Possible synthesis mechanism for MCM-48 molecular sievesusing SDS/CTAB as the template.g:packing parameter;V:total volume of surfactant hydrophobicchains plus any cosolvent between the chains;a0:effectivehydrophilic headgroup area at the aqueous-micelle surface;l:kinetic surfactant tail length.SDSCTABCTAB+SDSa0a0decreaseVlg increaseV increase4160-4162.
[22]Zhao Wei,Li Quanzhi,Wang Lina,et al.Synthesis of HighQuality MCM-48 with Binary Cationic-Nonionic Surfactants[J].Langmuir,2010,26(10):6982-6988.
[23]Maiti K,Mitra D,Mitra R N,et al.Self-Aggregation ofSynthesized Novel Bolaforms and Their Mixtures with So-dium Dodecyl Sufate(SDS)and CetyltrimethylammoniumBromide(CTAB)in Aqueous Medium[J].J Phys Chem B,2010,114(22):7499-7508.