Journal of Sol-Gel Science and Technology

, Volume 89, Issue 1, pp 29–36 | Cite as

Synthesis of hierarchically porous MgO monoliths with continuous structure via sol–gel process accompanied by phase separation

  • Xuanming Lu
  • Kazuyoshi Kanamori
  • Kazuki NakanishiEmail author
Brief Communication: Nano and macroporous materials (aerogels, xerogels, cryogels, etc.)


Hierarchically porous magnesium oxide, MgO, monoliths with a well-defined continuous macroporous structure have been synthesized via the sol–gel route accompanied by phase separation. Magnesium chloride hexahydrate was used as a precursor, and propylene oxide was used as an acid scavenger to raise the pH of a reaction solution homogenously. In order to obtain a crack-free monolith after heating in air, poly(vinylpyrrolidone), PVP, was employed as a scaffold of the skeleton as well as a phase separation controller to form the continuous macropores with higher homogeneity. Due to the moderate hydrogen-bonding interaction with magnesium hydroxide, PVP reinforces the gel network essentially composed of fine grained magnesium hydroxide. Even after the removal of all organic components by calcination, the porous gel samples maintained their monolithic form. On the other hand, an additional incorporation of 1,3,5-benzenetricarboxylic acid, H3BTC, was found to be effective in suppressing the oriented growth of the micrometer-sized crystalline phase. The polycrystalline MgO monoliths with specific surface area of 185, 64, and 48 m2 g−1 were prepared after heating at 400, 500, and 600 °C in air, respectively.

Appearances (upper) and SEM images(lower) of monolithic MgO-based gel before and after heat-treatment.


Magnesium oxide Sol–gel Phase separation Hierarchical pore structure Monoliths 



The present study has been performed under financial supports from Advanced Low Carbon Technology Research and Development Program (ALCA, Japan Science and Technology Agency).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Shi L, Chu Z, Liu Y, Jin W, Xu N (2014) In situ fabrication of three-dimensional graphene films on gold substrates with controllable pore structures for high-performance electrochemical sensing. Adv Funct Mater 24:7032–7041CrossRefGoogle Scholar
  2. 2.
    Collins G, Blomker M, Osiak M, Holmes JD, Bredol M, O’Dwyer C (2013) Three-dimensionally ordered hierarchically porous tin dioxide inverse opals and immobilization of palladium nanoparticles for catalytic applications. Chem Mater 25:4312–4320CrossRefGoogle Scholar
  3. 3.
    Tanaka N, Nagayama H, Kobayashi H, Ikegami T, Hosoya K, Ishizuka N, Lubda D (2000) Monolithic silica columns for HPLC, micro-HPLC, and CEC. J Sep Sci 23:111–116Google Scholar
  4. 4.
    Srinivas G, Krungleviciute V, Guo ZX, Yildirim T (2014) Exceptional CO2 capture in a hierarchically porous carbon with simultaneous high surface area and pore volume. Energy Environ Sci 7:335–342CrossRefGoogle Scholar
  5. 5.
    Nakanishi K, Soga N (1991) Phase separation in gelling silica-organic polymer solution: systems containing poly (sodium styrenesulfonate). J Am Ceram Soc 74:2518–2530CrossRefGoogle Scholar
  6. 6.
    Flory PJ (1942) Thermodynamics of high polymer solutions. J Chem Phys 10:51–61CrossRefGoogle Scholar
  7. 7.
    Huggins ML (1942) Some properties of solutions of long-chain compounds. J Phys Chem 46:151–158CrossRefGoogle Scholar
  8. 8.
    Konishi J, Fujita K, Nakanishi K, Hirao K (2006) Monolithic TiO2 with controlled multiscale porosity via a template-free sol-gel process accompanied by phase separation. Chem Mater 18:6069–6074CrossRefGoogle Scholar
  9. 9.
    Hasegawa G, Kanamori K, Nakanishi K, Hanada T (2010) Facile preparation of hierarchically porous TiO2 monoliths. J Am Ceram Soc 93:3110–3115CrossRefGoogle Scholar
  10. 10.
    Konishi J, Fujita K, Oiwa S, Nakanishi K, Hirao K (2008) Crystalline ZrO2 monoliths with well-defined macropores and mesostructured skeletons prepared by combining the alkoxy-derived sol–gel process accompanied by phase separation and the solvothermal process. Chem Mater 20:2165–2173CrossRefGoogle Scholar
  11. 11.
    Tokudome Y, Fujita K, Nakanishi K, Miura K, Hirao K (2007) Synthesis of monolithic Al2O3 with well-defined macropores and mesostructured skeletons via the sol–gel process accompanied by phase separation. Chem Mater 19:3393–3398CrossRefGoogle Scholar
  12. 12.
    Schubert U, Hüsing N (2012) Synthesis of inorganic materials. CPI Group Ltd, Croydon, UK, Chapter 4Google Scholar
  13. 13.
    Gash AE, Tillotson TM, Satcher Jr JH, Poco JF, Hrubesh LW, Simpson RL (2001) Use of epoxides in the sol-gel synthesis of porous iron (III) oxide monoliths from Fe (III) salts. Chem Mater 13:999–1007CrossRefGoogle Scholar
  14. 14.
    Baumann TF, Gash AE, Chinn SC, Sawvel AM, Maxwell RS, Satcher JH (2005) Synthesis of high-surface-area alumina aerogels without the use of alkoxide precursors. Chem Mater 17:395–401CrossRefGoogle Scholar
  15. 15.
    Kido Y, Nakanishi K, Miyasaka A, Kanamori K (2012) Synthesis of monolithic hierarchically porous iron-based xerogels from iron (III) salts via an epoxide-mediated sol-gel process. Chem Mater 24:2071–2077CrossRefGoogle Scholar
  16. 16.
    Kido Y, Nakanishi K, Okumura N, Kanamori K (2013) Hierarchically porous nickel/carbon composite monoliths prepared by sol-gel method from an ionic precursor. Microporous Mesoporous Mater 176:64–70CrossRefGoogle Scholar
  17. 17.
    Kido Y, Hasegawa G, Kanamori K, Nakanishi K (2014) Porous chromium-based ceramic monoliths: oxides (Cr2O3), nitrides (CrN), and carbides (Cr3C2). J Mater Chem A 2:745–752CrossRefGoogle Scholar
  18. 18.
    Fukumoto S, Nakanishi K, Kanamori K (2015) Direct preparation and conversion of copper hydroxide-based monolithic xerogels with hierarchical pores. New J Chem 39:6771–6777CrossRefGoogle Scholar
  19. 19.
    Gash AE, Satcher Jr JH, Simpson RL (2004) J Non-Cryst Solids 350:145–151CrossRefGoogle Scholar
  20. 20.
    Liu M, Yan X, Liu H, Yu W (2000) An investigation of the interaction between polyvinylpyrrolidone and metal cations. React Funct Polym 44:55–64CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Xuanming Lu
    • 1
  • Kazuyoshi Kanamori
    • 1
  • Kazuki Nakanishi
    • 1
    Email author
  1. 1.Department of Chemistry, Graduate School of ScienceKyoto University, Kitashirakawa, Sakyo-kuKyotoJapan

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