Controllable preparation of highly uniform γ-alumina microspheres via the sol–gel route for alkoxide in a coaxial microchannel

  • Huilin Yi
  • Yanchun Wan
  • Yang Zhang
  • Yujun WangEmail author
  • Weiyang FeiEmail author
  • Guangsheng Luo
Original Paper: Sol-gel and hybrid materials for catalytic, photoelectrochemical and sensor applications


This study describes a novel and facile route for fabricating highly uniform γ-alumina microspheres with controllable size, morphology, and pore structure by integrating the sol–gel route for alkoxide with “temperature/pH-induced gelation” in a coaxial microchannel. Taking advantage of the controllability of the microfluidic devices and Al–O–Al chains formed by the sol–gel route of aluminum alkoxide, the uniformity of the microspheres was assured, and the mechanical strength of the microspheres was greatly improved to 18–27 N/mm2. The effects of the continuous phase composition and two-phase flow rate on the size, morphology, and pore structure of the obtained microspheres were investigated. When triocylamine (TOA) was added to the continuous phase and the two-phase flow rate ratio was larger than 188, the as-prepared microspheres had a smooth surface and good sphericity; otherwise, the microspheres had poor spheriticy and included many ravines on the surface, which can be explained by the mutual influence of long-lasting movements of molecular chains resulted from low gelation speed and inner circulation of the droplets. Under different continuous phase compositions, the average pore diameter, pore volume, and specific surface area ranged from 7 to 12 nm, 0.89 to 1.58 mL/g, and 293.7 to 387.7 m2/g, respectively.


  • Sol–gel route was combined with temperature/pH-induced gelation in a microchannel.

  • The size, morphology, and pore structure were strictly controlled by preparation conditions.

  • The cause of ravines was explained by different gelation speed and inner circulation.

  • The crushing strength of the microspheres was greatly improved to 18–27 N/mm2.


Sol–gel route Temperature/pH-induced gelation Coaxial microchannel γ-Al2O3 microspheres 



This work was financially supported by the National Basic Research Program of China (Grant No. 2013CB733600), the National Natural Science Foundation of China (Grant Nos. 21276140 and 21036002), and the PetroChina Co., Ltd. (Grant No. 2016A-1803).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Pius IC, Bhanushali RD, Pillai KT, Mukerjee SK, Vaidya VN (1999) Studies on the sorption of Pu(IV) on alumina microspheres from nitric acid—oxalic acid solutions. J Radioanal Nucl Chem 240(3):981–985CrossRefGoogle Scholar
  2. 2.
    Jia JF, Junko KH, Kondo N, Domen K, Tamaru K (2000) Selective hydrogenation of acetylene over Au/Al2O3 catalyst. J Phys Chem B 104:11153–11156CrossRefGoogle Scholar
  3. 3.
    Pillai KT, Kamat RV, Vaidya VN (2001) Preparation of porous alumina microspheres by internal gelation method. Trans Indian Ceram Soc 60(3):150–154CrossRefGoogle Scholar
  4. 4.
    Liu XM, Li X, Yan ZF (2012) Facile route to prepare bimodal mesoporous γ-Al2O3 as support for highly active CoMo-based hydrodesulfurization catalyst. Appl Catal B: Environ 121-122:50–56CrossRefGoogle Scholar
  5. 5.
    Trueba M, Trasatti SP (2005) γ-Alumina as a support for catalysts: a review of fundamental aspects. Eur J Inorg Chem 17:3393–3403CrossRefGoogle Scholar
  6. 6.
    Khan NA, Shaikhutdinov S, Freund H-J (2006) Acetylene and ethylene hydrogenation on alumina supported Pd-Ag model catalysts. Catal Lett 108(3-4):159–164CrossRefGoogle Scholar
  7. 7.
    Reyes P, Fernandez J, Pecchi G, Fierro JLG (1998) Resistance to sulphur poisoning of alumina-supported iridium catalysts in toluene hydrogenation and methylcyclohexane dehydrogenation. J Chem Technol Biotechnol 73:1–6CrossRefGoogle Scholar
  8. 8.
    Qi F, Xu XX, Xu J, Wang YL, Yang JL (2014) A novel way to prepare hollow sphere ceramics. J Am Ceram Soc 97(10):3341–3347CrossRefGoogle Scholar
  9. 9.
    Gao Y, Ma JT, Zhao XY, Hao SC, Deng CS (2015) The formation of alumina ceramic microspheres by internal gelation process. Key Eng Mater 655:103–107CrossRefGoogle Scholar
  10. 10.
    Sousa JJ, Sousa A, Podczeck F, Newton JM (2002) Factors influencing the physical characteristics of pellets obtained by extrusion-spheronization. Int J Pharmaceutics 232:91–106CrossRefGoogle Scholar
  11. 11.
    Chu LY, Utada SA, Shah RK, Kim J-W, Weitz AD (2007) Controllable monodisperse multiple emulsions. Angew Chem 46:8970–8974CrossRefGoogle Scholar
  12. 12.
    Wang W, Xie R, Ju X-J, Luo T, Liu L, Weitz AD, Chu LY (2011) Controllable microfluidic production of multicomponent multiple emulsions. Lab Chip 11(9):1587–1592CrossRefGoogle Scholar
  13. 13.
    Wan YC, Yi HL, Wang YJ, Luo GS (2018) Preparation of uniform γ-alumina microspheres with large pore volumes in a coaxial microchannel. Ind Eng Chem Res 57(34):11636–11644CrossRefGoogle Scholar
  14. 14.
    Leenaars AFM, Keizer K, Burggraaf AJ (1984) The preparation and characterization of alumina membranes with ultra-fine pores. J Mater Sci 19:1077–1088CrossRefGoogle Scholar
  15. 15.
    Yoldas BE (1975) Alumina gels that form porous transparent Al2O3. J Mater Sci 10:1856–1860CrossRefGoogle Scholar
  16. 16.
    Zhao SZ, Chen BD, Qi QQ, Shu RD, Qiu ZP, Ren JZ (2011) Preparation of polyvinyl alcohol hydrogel microspheres with high strength. Chem J Chin Univ 32:2437–2440Google Scholar
  17. 17.
    Hirrien M, Chevillard C, Desbrieres J, Axelos MAV, Rinaudo M (1998) Thermogelation of methylcelluloses new evidence for understanding the gelation mechanism. Polymer 39(25):6251–6259CrossRefGoogle Scholar
  18. 18.
    Kobayashi K, Huang C-I, Lodge TP (1999) Thermoreversible gelation of aqueous methylcellulose solutions. Macromolecules 32:7070–7077CrossRefGoogle Scholar
  19. 19.
    Paul AH, Pitt Jr WW, Robinson SM, Ryon AD (1983) Preparation of metal oxide gel spheres with hexamethylenetetramine as an ammonia donor. Ind Eng Chem Prod Res Dev 22:461–466CrossRefGoogle Scholar
  20. 20.
    Sawant RM, Chaudhuri NK, Ramakumar KL (2002) Sequential determination of urea and HMTA in the process solution of sol–gel route of advanced nuclear fuel fabrication. J Radioanal Nucl Chem 252(3):485–489CrossRefGoogle Scholar
  21. 21.
    Yang WJ, Wang K, Wang XT (2012) Influence of alunima sol preparation conditions on its gelation and sphere formation ability. Chem Eng 40(9):16–23Google Scholar
  22. 22.
    Li SW, Xu JH, Wang YJ, Luo GS (2009) Liquid-liquid two-phase flow in pore array microstructured devices for scaling-up of nanoparticle preparation. AIChE J 55(12):3041–3051CrossRefGoogle Scholar
  23. 23.
    Zhang JS, Liu GT, Wang K, Luo GS (2015) Effect of transfer on liquid-liquid dispersion in microchannels. CIESC J 66(8):2940–2946Google Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.State Key Laboratory of Chemical Engineering, Department of Chemical EngineeringTsinghua UniversityBeijingPR China

Personalised recommendations