Structure and characteristics of mesoporous silica synthesized in acid medium and its reaction mechanism

Abstract

Structure and pore characteristics of the mesoporous silica, synthesized in acid medium were studied by means of XRD, HRTEM, BET, FT-IR, DSC-TGA, and the reaction mechanism was also investigated deeply. The results show that mesopores in the sample possess hexagonal arrays obviously, whereas the structure of silica matrix is amorphous. The results also show that the acting mode of silica, and CTMA⁺ inside the mesopores was chemical bonding force. The structure of mesoporous silica was mainly dependent on the aggregational condition of micelle of CTMA⁺ as well as their liquid-crystallized status. In addition, condensation and dehydration of silicate radicals were accompanied in the process of calcination, which resulted in the mesoporous structure ordered in local range and the pore sizes largening.

Keywords

porous silica / mesoporous molecular sieves / isothermal adsorption / CTMABr

References

[1] Lu Yunfeng, Gangull Rahul, Drewien Celeste A, . Continuous Formation of Supported Cubic and Hexagonal Mesoporous Films by Sol-gel Dip-coating. Nature, 1997, 389(25): 364-368.

[2] Wang Lian-zhou, Shi Jian-lin, Yu Jian, . Study on the Synthesis and Mechanicsm of Mesoporous Silica with Hexastyle Structure. Journal of Inorganic Materials, 1999, 14(4): 558-562.

[3] Li Zhengping, Gao Lian. Synthesis and Characterization of MCM-41 Decotated with CuO Paricles. Journal of Physics and Chemistry of Solids, 2003, 65(2): 223-228.

[4] Wu Yucheng, Zhang Lide, Li Guanghai. Synthesis and Character of Nanocomposites with Palladium Embedded in Mesoporous Silica. Materials Research Bulletin, 2001, 36(1–2): 253-263.

[5] Bian Li-juan, Xi Hong-an, Qian Xue-feng, . Synthesis and Luminescence Property of Rare Earth Complex Nanoparticles Dispersed within Pores of Modified Mesoporous Silica. Materials Research Bulletin, 2002, 37(15): 2293-2301.

[6] Chen Xiaoyin, Huang Limin, Ding Guozhong, . Characterization and Catalytic Performance of Mesoporous Molecular Sieves Al-MCM-41 Materials. Catalysis. Letters, 1997, 44(1–2): 123-128.

[7] Endoh K, Suga H. Phase Behavior of CTAB: O-iodophenol Binary System. Thermochimica Acta, 1999, 334(1–2): 89-96.

[8] Luo Xiquan, Luo Yi, Wang Chenhua. Handbook of Surfactant Products, 1997 China: Light Industry Press. 122-122.

[9] Choma Jerzy, Jaroniec Mietek, Wanda B, . Critical Appraisal of Classical Methods for Determination of Mesopore Size Distributions of MCM-41 Materials. Applied Surface Science, 2002, 196(1–4): 216-223.

[10] Wloch J, Rozwadowski M, Lezanska M, . Analysis of the Pore Structure of the MCM-41 Materials. Applied Surface Science, 2002, 191(1–4): 368-374.

[11] Kresge C T, Leonowlez M E, Roth W J, . Ordered Mesoporous Molecular Sieves Synthesed by a Liquid Crystal Template Mechanism. Nature, 1992, 395(22): 710-712.

[12] Hench Larry L, West Jon K. The Sol-Gel Process. Chemical Reviews, 1990, 90(1): 33-72.

[13] Zhang Jin Z, Wang Zhong-lin, Liu Jun, . Self-Assembled Nanostructures, 2003 New York: Kluwer Academic/Plenum Publishers. 13-14.

[14] Yang Chun, Jia Xue-ping. Synthesis of Hexagonal Mesoporous Silica in Acidic Medium (II) Effect of Synthetic Temperature and Time, and a Compareison with the Synthesis in Basic Medium. Chenese journal of Inorganic Chemistry, 2001, 17(2): 256-262.