碱性催化剂对SiO_2气凝胶性能的影响研究
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摘要
以工业水玻璃为硅源,采用LiOH、NaOH、KOH、NH_3·H_2O为催化剂,通过溶胶-凝胶法常压环境干燥疏水改性制备SiO_2气凝胶。利用FT-IR、TG-DTA、SEM以及BET对气凝胶的化学结构、热稳定性、微观形貌及比表面积和孔结构进行了表征测试。结果表明,碱性催化剂促使SiO_2溶胶-凝胶转化时间急剧缩短,由5840min缩短到30min左右;同时热稳定性明显提高,热分解温度由375℃上升到400℃以上。碱性金属离子催化作用下SiO_2气凝胶在1.7和32nm处呈现双孔结构,孔容保持在2.5～3.5cm3/g,说明在弱酸性环境下碱金属离子使的SiO_2气凝胶在保持三维网状结构的同时加大了SiO_2纳米粒子之间的接触面积。
By using industrial water glass as silicon source,LiOH,NaOH,KOH and NH_3·H_2O as the catalysts,the light and hydrophobic SiO_2 aerogels were prepared successfully by the sol-gel method via ambient pressure drying process.The chemical structure,thermal stability,microscopic morphology,specific surface area and pore structure of SiO_2 aerogels were characterized by FT-IR,TG-DTA,SEM and BET.The results showed that the alkaline catalyst could shorten the gel time sharply from 5 840 to 30 min.The thermal stability was significantly improved and the decomposition temperature increased from 375 ℃ to above 400 ℃.Alkali metal ions could produce "alkali excitation" in a weakly acidic environment,which increased the contact area between SiO_2 nanoparticles and maintained a three-dimensional network structure.This excitation made SiO_2 aerogels produce double pore structure at 1.7 and 32 nm,and the pore volume was maintained at 2.5 to 3.5 cm3/g.
By using industrial water glass as silicon source,LiOH,NaOH,KOH and NH_3·H_2O as the catalysts,the light and hydrophobic SiO_2 aerogels were prepared successfully by the sol-gel method via ambient pressure drying process.The chemical structure,thermal stability,microscopic morphology,specific surface area and pore structure of SiO_2 aerogels were characterized by FT-IR,TG-DTA,SEM and BET.The results showed that the alkaline catalyst could shorten the gel time sharply from 5 840 to 30 min.The thermal stability was significantly improved and the decomposition temperature increased from 375 ℃ to above 400 ℃.Alkali metal ions could produce "alkali excitation" in a weakly acidic environment,which increased the contact area between SiO_2 nanoparticles and maintained a three-dimensional network structure.This excitation made SiO_2 aerogels produce double pore structure at 1.7 and 32 nm,and the pore volume was maintained at 2.5 to 3.5 cm3/g.
引文
[1] Feng Yisi,Zhang Lide.Recent progress in research on mesoporous silica nanocompocite[J].Journal of Functional Materials,2003,34(06):619-621(in Chinese).冯乙巳,张立德.介孔二氧化硅干凝胶和气凝胶纳米复合材料的研究进展[J].功能材料,2003,34(06):619-621.
[2] Jp R,Ma M,Sc J.Tailoring mechanical properties of aerogels for aerospace applications[J].ACS Applied Materials and Interfaces,2011,3(03):613.
[3] Jelle B P,Baetens R,Gustavsen A.Aerogel insulation for building applications[M].New Jersey:Wiley-VCH Verlag GmbH&Co KGaA,2015:1385-1412.
[4] Pierre A C.Aerogel catalysts[J].Advances in Science and Technology,2010,65:174-183.
[5] Martins M,Barros A A,Quraishi S,et al.Preparation of macroporous alginate-based aerogels for biomedical applications[J].Journal of Supercritical Fluids,2015,106:152-159.
[6] Z U,C E.An emerging platform for drug delivery:aerogel based systems.[J].Journal of Controlled Release,2014,177(2):51.
[7] Guo Sitong,Wu Huijun,Yang Lixiu,et al.Influence of preparation parameters on structure and performance of silica aerogel:a review[J].Materials Review,2017,31(7):38-44(in Chinese).郭思彤,吴会军,杨丽修,等.制备参数对SiO2气凝胶结构与性能影响的研究进展[J].材料导报,2017,31(7):38-44.
[8] Rao A V,Rao A P,Kulkarni M M.Influence of gel aging and Na2SiO3/H2O molar ratio on monolithicity and physical properties of water–glass-based aerogels dried at atmospheric pressure[J].Journal of Non-Crystalline Solids,2004,350(24):224-229.
[9] Chen Jun,Wang Jichao,Ni Xingyuan,et al.Preparation of silica aerogels with non-ionic exchange water glass[J].Journal of Functionals Materials,2009,40(01):149-151(in Chinese).沈军,王际超,倪星元,等.以水玻璃为源常压制备高保温二氧化硅气凝胶[J].功能材料,2009,40(01):149-151.
[10] Deng Zhongsheng,Wei Jiandong,Wang Jue,et al.Silica aerogel prepared from polyethoxydisiloxanes[J].Journal of Functional Materials,2000,31(03):296-298(in Chinese).邓忠生,魏建东,王珏,等.由多聚硅氧烷制备二氧化硅气凝胶[J].功能材料,2000,31(03):296-298.
[11] Rao A P,Rao A V,Pajonk G M,et al.Effect of solvent exchanging process on the preparation of the hydrophobic silica aerogels by ambient pressure drying method using sodium silicate precursor[J].Journal of Materials Science,2007,42(20):8418-8425.
[12] Chen Yimin,Xie Kai,Zhan Dafang,et al.Preparation and characterization of hydrophobic SiO2aerogel[J].Journal of Functional Materials,2005,36(06):903-905(in Chinese).陈一民,谢凯,赵大方,等.疏水SiO2气凝胶的制备及表征[J].功能材料,2005,36(06):903-905.
[13] Lee S,Cha Y C,Hwang H J,et al.The effect of pH on the physicochemical properties of silica aerogels prepared by an ambient pressure drying method[J].Materials Letters,2007,61(14):3130-3133.
[14] Jeong A Y,Koo S M,Kim D P.Characterization of hydrophobic SiO2powders prepared by surface modification on wet gel[J].Journal of Sol-Gel Science and Technology,2000,19(1-3):483-487.
[15] Shi Fei.Preparation,characterization and properties of silica aerogel via ambient pressure drying[D].Dalian:Dalian University of Technology,2007(in Chinese).史非.常压干燥制备SiO2气凝胶及其结构、性能研究[D].大连:大连理工大学,2007.
[16] Tang X,Sun A,Chu C,et al.A novel silica nanowiresilica composite aerogels dried at ambient pressure[J].Materials&Design,2017,115:415-421.
[17] Thommes M,Kaneko K,Neimark A V,et al.Physisorption of gases,with special reference to the evalua-tion of surface area and pore size distribution(IUPAC Technical Report)[J].Chemistry International,2016,38(1):25.
[2] Jp R,Ma M,Sc J.Tailoring mechanical properties of aerogels for aerospace applications[J].ACS Applied Materials and Interfaces,2011,3(03):613.
[3] Jelle B P,Baetens R,Gustavsen A.Aerogel insulation for building applications[M].New Jersey:Wiley-VCH Verlag GmbH&Co KGaA,2015:1385-1412.
[4] Pierre A C.Aerogel catalysts[J].Advances in Science and Technology,2010,65:174-183.
[5] Martins M,Barros A A,Quraishi S,et al.Preparation of macroporous alginate-based aerogels for biomedical applications[J].Journal of Supercritical Fluids,2015,106:152-159.
[6] Z U,C E.An emerging platform for drug delivery:aerogel based systems.[J].Journal of Controlled Release,2014,177(2):51.
[7] Guo Sitong,Wu Huijun,Yang Lixiu,et al.Influence of preparation parameters on structure and performance of silica aerogel:a review[J].Materials Review,2017,31(7):38-44(in Chinese).郭思彤,吴会军,杨丽修,等.制备参数对SiO2气凝胶结构与性能影响的研究进展[J].材料导报,2017,31(7):38-44.
[8] Rao A V,Rao A P,Kulkarni M M.Influence of gel aging and Na2SiO3/H2O molar ratio on monolithicity and physical properties of water–glass-based aerogels dried at atmospheric pressure[J].Journal of Non-Crystalline Solids,2004,350(24):224-229.
[9] Chen Jun,Wang Jichao,Ni Xingyuan,et al.Preparation of silica aerogels with non-ionic exchange water glass[J].Journal of Functionals Materials,2009,40(01):149-151(in Chinese).沈军,王际超,倪星元,等.以水玻璃为源常压制备高保温二氧化硅气凝胶[J].功能材料,2009,40(01):149-151.
[10] Deng Zhongsheng,Wei Jiandong,Wang Jue,et al.Silica aerogel prepared from polyethoxydisiloxanes[J].Journal of Functional Materials,2000,31(03):296-298(in Chinese).邓忠生,魏建东,王珏,等.由多聚硅氧烷制备二氧化硅气凝胶[J].功能材料,2000,31(03):296-298.
[11] Rao A P,Rao A V,Pajonk G M,et al.Effect of solvent exchanging process on the preparation of the hydrophobic silica aerogels by ambient pressure drying method using sodium silicate precursor[J].Journal of Materials Science,2007,42(20):8418-8425.
[12] Chen Yimin,Xie Kai,Zhan Dafang,et al.Preparation and characterization of hydrophobic SiO2aerogel[J].Journal of Functional Materials,2005,36(06):903-905(in Chinese).陈一民,谢凯,赵大方,等.疏水SiO2气凝胶的制备及表征[J].功能材料,2005,36(06):903-905.
[13] Lee S,Cha Y C,Hwang H J,et al.The effect of pH on the physicochemical properties of silica aerogels prepared by an ambient pressure drying method[J].Materials Letters,2007,61(14):3130-3133.
[14] Jeong A Y,Koo S M,Kim D P.Characterization of hydrophobic SiO2powders prepared by surface modification on wet gel[J].Journal of Sol-Gel Science and Technology,2000,19(1-3):483-487.
[15] Shi Fei.Preparation,characterization and properties of silica aerogel via ambient pressure drying[D].Dalian:Dalian University of Technology,2007(in Chinese).史非.常压干燥制备SiO2气凝胶及其结构、性能研究[D].大连:大连理工大学,2007.
[16] Tang X,Sun A,Chu C,et al.A novel silica nanowiresilica composite aerogels dried at ambient pressure[J].Materials&Design,2017,115:415-421.
[17] Thommes M,Kaneko K,Neimark A V,et al.Physisorption of gases,with special reference to the evalua-tion of surface area and pore size distribution(IUPAC Technical Report)[J].Chemistry International,2016,38(1):25.