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Preparation of macroporous zirconia monoliths from ionic precursors via an epoxide-mediated sol-gel process accompanied by phase separation

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ABSTRACT

Monolithic macroporous zirconia (ZrO2) derived from ionic precursors has been successfully fabricated via the epoxide-mediated sol-gel route accompanied by phase separation in the presence of propylene oxide (PO) and poly(ethylene oxide) (PEO). The addition of PO used as an acid scavenger mediates the gelation, whereas PEO enhances the polymerization-induced phase separation. The appropriate choice of the starting compositions allows the production of a macroporous zirconia monolith with a porosity of 52.9% and a Brunauer–Emmett–Teller (BET) surface area of 171.9 m2 · g−1. The resultant dried gel is amorphous, whereas tetragonal ZrO2 and monoclinic ZrO2 are precipitated at 400 and 600 °C, respectively, without spoiling the macroporous morphology. After solvothermal treatment with an ethanol solution of ammonia, tetragonal ZrO2 monoliths with smooth skeletons and well-defined mesopores can be obtained, and the BET surface area is enhanced to 583.8 m2 · g−1.

No MeSH data available.


SEM images of dried ZrO2 gels prepared with various VPO: (a) 0.50 mL (P1), (b) 0.52 mL (P2), (c) 0.54 mL (P3) and (d) 0.56 mL (P4).
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Figure 1: SEM images of dried ZrO2 gels prepared with various VPO: (a) 0.50 mL (P1), (b) 0.52 mL (P2), (c) 0.54 mL (P3) and (d) 0.56 mL (P4).

Mentions: The SEM microphotographs of the dried gels with different PO contents are shown in figure 1. It can be seen that the VPO has a great impact on the macroporous structure of ZrO2 monoliths. The morphology of gels changes from fine aggregated particles to isolated macropores. When VPO is small, the sol-gel process freezes the late stage morphology of phase separation; only aggregated particles are obtained (figure 1(a)). The increasing VPO can dramatically shorten the gelation time of the system. Therefore, the early stage morphology of phase separation is acquired when too much PO is added (figure 1(d)).


Preparation of macroporous zirconia monoliths from ionic precursors via an epoxide-mediated sol-gel process accompanied by phase separation
SEM images of dried ZrO2 gels prepared with various VPO: (a) 0.50 mL (P1), (b) 0.52 mL (P2), (c) 0.54 mL (P3) and (d) 0.56 mL (P4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036470&req=5

Figure 1: SEM images of dried ZrO2 gels prepared with various VPO: (a) 0.50 mL (P1), (b) 0.52 mL (P2), (c) 0.54 mL (P3) and (d) 0.56 mL (P4).
Mentions: The SEM microphotographs of the dried gels with different PO contents are shown in figure 1. It can be seen that the VPO has a great impact on the macroporous structure of ZrO2 monoliths. The morphology of gels changes from fine aggregated particles to isolated macropores. When VPO is small, the sol-gel process freezes the late stage morphology of phase separation; only aggregated particles are obtained (figure 1(a)). The increasing VPO can dramatically shorten the gelation time of the system. Therefore, the early stage morphology of phase separation is acquired when too much PO is added (figure 1(d)).

View Article: PubMed Central - PubMed

ABSTRACT

Monolithic macroporous zirconia (ZrO2) derived from ionic precursors has been successfully fabricated via the epoxide-mediated sol-gel route accompanied by phase separation in the presence of propylene oxide (PO) and poly(ethylene oxide) (PEO). The addition of PO used as an acid scavenger mediates the gelation, whereas PEO enhances the polymerization-induced phase separation. The appropriate choice of the starting compositions allows the production of a macroporous zirconia monolith with a porosity of 52.9% and a Brunauer–Emmett–Teller (BET) surface area of 171.9 m2 · g−1. The resultant dried gel is amorphous, whereas tetragonal ZrO2 and monoclinic ZrO2 are precipitated at 400 and 600 °C, respectively, without spoiling the macroporous morphology. After solvothermal treatment with an ethanol solution of ammonia, tetragonal ZrO2 monoliths with smooth skeletons and well-defined mesopores can be obtained, and the BET surface area is enhanced to 583.8 m2 · g−1.

No MeSH data available.