Benzoic acid as a selector-modulator in the synthesis of MIL-88B(Cr) and nano-MIL-101(Cr)
The concentration of benzoic acid was found to exercise efficient control over the formation of either MIL-101(Cr) or MIL-88B(Cr) under otherwise similar hydrothermal synthetic conditions. Nanocrystals of MIL-101(Cr) with ∼100 nm average size and excellent S BET = 3467 m 2 g −1 are obtained at lower...
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Veröffentlicht in: | Dalton transactions : an international journal of inorganic chemistry 2019-01, Vol.48 (3), p.989-996 |
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Sprache: | eng |
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Zusammenfassung: | The concentration of benzoic acid was found to exercise efficient control over the formation of either MIL-101(Cr) or MIL-88B(Cr) under otherwise similar hydrothermal synthetic conditions. Nanocrystals of MIL-101(Cr) with ∼100 nm average size and excellent
S
BET
= 3467 m
2
g
−1
are obtained at lower concentrations of benzoic acid, while at higher concentrations the microparticulated MIL-88B(Cr) product is formed. Hereby a new efficient synthetic method towards the elusive MIL-88B(Cr), yet reported only once without synthetic details, is proposed. The obtained MIL-88B(Cr) has an interesting and potentially valuable property of retaining its high-volume form (
V
cell
∼ 2000 Å
3
) after thermal activation. The degassing of MIL-88B(Cr) in a vacuum at 250 °C yields a porous material with a
S
BET
area of 1136 m
2
g
−1
, which is around the theoretical maximum. The transition to the denser 'closed' form (
V
cell
∼ 1500 Å
3
) occurs only at 350 °C, when all of the benzoate/benzoic acid, hindering the process, is removed.
The concentration of benzoic acid was found to exercise efficient control over the formation of either MIL-101(Cr) or MIL-88B(Cr) under otherwise similar hydrothermal synthetic conditions. |
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ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/c8dt04186e |