Al-SO_3H-SBA-15孔径可控制备及其对醋酸与异丁烯加成酯化的催化性能
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摘要
以均三甲苯为调节剂,采用一步共缩合法制备一系列孔径可调(3.71~4.76 nm)、高比表面积、Al掺杂且磺酸嫁接的介孔分子筛SBA-15(x-AS-SBA-15)。通过小角度X线衍射(SAXRD)、N_2吸附-脱附、热分析(TG)、NH_3程序升温脱附(NH_3-TPD)、傅里叶变换红外光谱(FT-IR)、紫外-可见光谱(UV-Vis)和扫描电子显微镜(SEM)等手段对x-AS-SBA-15的结构、酸量等理化性质进行表征。结果表明:x-AS-SBA-15仍然留有六方介孔的相结构,但是随着x值的增大,有序介孔分子筛的孔径减小,有序度有所降低。同时研究了x-AS-SBA-15在醋酸与异丁烯无溶剂加成酯化反应中的催化性能,结果表明:50-AS-SBA-15具有最优的催化活性和产物选择性。50-AS-SBA-15用量为醋酸的5%、反应温度为30℃、烯酸摩尔比为3∶1时,醋酸转化率为93.5%,醋酸叔丁酯选择性为94.0%。催化剂拥有良好的稳定性,重复利用5次催化活性依旧保持稳定。
The modified SBA-15 materials( x-AS-SBA-15) with Al ions and organo-sulfonic acid were synthesized in a one-pot approach of co-condensing inorganic-organic reagents in the presence of different amounts of trimethylbenzene( TMB). The obtained materials was characterized by small angle X-ray diffraction( SAXRD),N_2 adsorption-desorption,thermal analysis( TG),temperature programmed desorption of NH_3( NH_3-TPD),Fourier transform infrared spectroscopy( FT-IR),ultraviolet-visible spectroscopy( UV-Vis) and scanning electron microscope( SEM) techniques. Results showed that x-ASSBA-15 had typically mesoporous structure with tunable pore size of 3. 71-4. 76 nm and huge specificsurface area. However the pore size and the specific pore volume decreased with the increase of TMB amount. The activity of x-AS-SBA-15 in the additive reaction of acetic acid with isobutene was investigated. It turned out that the 50-AS-SBA-15 had the best catalytic activity and the product selectivity.The conversion of acetic acid could reach 93. 5% with the selectivity of tertiary butyl acetate as high as 94. 0% over 50-AS-SBA-15,using a catalyst loading of 5% and isobutene/acetic acid molar ratio of 3 ∶1 under 30 ℃.The 50-AS-SBA-15 catalyst could be reused up to five times without significant loss of catalytic activity.
The modified SBA-15 materials( x-AS-SBA-15) with Al ions and organo-sulfonic acid were synthesized in a one-pot approach of co-condensing inorganic-organic reagents in the presence of different amounts of trimethylbenzene( TMB). The obtained materials was characterized by small angle X-ray diffraction( SAXRD),N_2 adsorption-desorption,thermal analysis( TG),temperature programmed desorption of NH_3( NH_3-TPD),Fourier transform infrared spectroscopy( FT-IR),ultraviolet-visible spectroscopy( UV-Vis) and scanning electron microscope( SEM) techniques. Results showed that x-ASSBA-15 had typically mesoporous structure with tunable pore size of 3. 71-4. 76 nm and huge specificsurface area. However the pore size and the specific pore volume decreased with the increase of TMB amount. The activity of x-AS-SBA-15 in the additive reaction of acetic acid with isobutene was investigated. It turned out that the 50-AS-SBA-15 had the best catalytic activity and the product selectivity.The conversion of acetic acid could reach 93. 5% with the selectivity of tertiary butyl acetate as high as 94. 0% over 50-AS-SBA-15,using a catalyst loading of 5% and isobutene/acetic acid molar ratio of 3 ∶1 under 30 ℃.The 50-AS-SBA-15 catalyst could be reused up to five times without significant loss of catalytic activity.
引文
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[4]ZHANG W H,ZHANG L,XIU J,et al.Pore size design of ordered mesoporous silicas by controlling micellar properties of triblock copolymer EO20PO70EO20[J].Microporous and mesoporous materials,2006,89(1):179.
[5]韩冰,王海青,孔岩.六方相介孔Si O2孔径及壁厚调节[J].化工新型材料,2013,41(9):102.
[6]张光旭,高为芳,蔡卫权.以离子液体为模板剂合成MCM-41的研究:不同扩孔剂对介孔分子筛MCM-41孔径结构的影响[J].分子催化,2008,22(6):497.
[7]周峰,汤吉海,陈献,等.SO3H-MCM-41对丙烯酸和异丁烯加成反应的催化性能[J].石油学报(石油加工),2014,30(4):629.
[8]CHEN X,FENG J,FEI Z,et al.Synthesis of tert-butyl acetate via eco-friendly additive reaction over mesoprous silica catalysts with balanced Br9nsted and Lewis acid sites[J].Journal of porous materials,2016,23(1):255.
[9]BHANGE P,BHANGE D S,PRADHAN S,et al.Direct synthesis of well-ordered mesoporous Al-SBA-15 and its correlation with the catalytic activity[J].Applied catalysis A:general,2011,400(1):176.
[10]MARGOLESE D,MELERO J A,CHRISTIANSEN S C,et al.Direct syntheses of ordered SBA-15 mesoporous silica containing sulfonic acid groups[J].Chemistry of materials,2000,12(8):2448.
[11]ERDEM B,ERDEM S,OKSUZOGLU R,et al.High-surface-area SBA-15-SO3H with enhanced catalytic activity by the addition of poly(ethylene glycol)[J].Journal of porous materials,2013,20(5):1041.
[12]LIN S,SHI L,CARROTT M M L R,et al.Direct synthesis without addition of acid of Al-SBA-15 with controllable porosity and high hydrothermal stability[J].Microporous and mesoporous materials,2011,142(2):526.
[13]YANG X L,DAI W L,CHEN H,et al.Novel tungsten-containing mesoporous HMS material:its synthesis,characterization and catalytic application in the selective oxidation of cyclopentene to glutaraldehyde by aqueous H2O2[J].Applied catalysis A:general,2005,283(1):1.
[14]YANG L M,WANG Y J,LUO G S,et al.Simultaneous removal of copolymer template from SBA-15 in the crystallization process[J].Microporous and mesoporous materials,2005,81(1):107.
[15]MARTINEZ M L,COSTA M B G,MONTI G A,et al.Synthesis,characterization and catalytic activity of Al-SBA-3 mesoporous catalyst having variable silicon-to-aluminum ratios[J].Microporous and mesoporous materials,2011,144(1):183.
[16]LIANG X,YANG R,LI G,et al.Phenol hydroxylation over Feincorporated mesoporous materials prepared by coprecipitation[J].Microporous and mesoporous materials,2013,182(6):62.