TY - JOUR
T1 - Supercooling suppression in the tetrahydrofuran clathrate hydrate formation
AU - Machida, Hironobu
AU - Sugahara, Takeshi
AU - Hirasawa, Izumi
N1 - Funding Information:
This paper is based on results obtained from a project, JPNP15007, commissioned by the New Energy and Industrial Technology Development Organization (NEDO). T. S. was supported by JSPS KAKENHI (Grant no. JP18K05032). The authors would like to thank Kaneka Techno Research Corporation for technical assistance with the STEM and EDX experiments.
Publisher Copyright:
© 2022 The Royal Society of Chemistry.
PY - 2022/9/7
Y1 - 2022/9/7
N2 - Generally, supercooling as large as about 25 K is necessary to form tetrahydrofuran clathrate hydrate (THF hydrate). In the present study, we have investigated how the existence of various additives affects the degree of supercooling (ΔT) in the THF hydrate formation without any external stimulus. The addition of either AgO or Ag3PO4 yields the best ΔT suppression, where ΔT was approximately 4 K, much smaller than 25 K. Raman spectra reveal that, in the supercooled THF aqueous solution with AgO before crystallization, the THF molecule forms a coordination bond with AgO, whereas it forms a hydrogen bond with a water molecule in the system without AgO. The oxygen atom of the THF molecules, which is a hydrogen-bonding site, was oriented to a AgO molecule in the aqueous solution. The orientation and the subsequent interruption of the hydrogen bond make it easy to form a hydration shell around the THF molecule. Scanning Transmission Electron Microscopy images by using the freeze-fracture replica method reveal that a cluster, which is the smallest structural unit of a crystal, includes Ag-containing nanoparticles formed from AgO or Ag3PO4, which accelerate the cluster formation. As a result, the addition of AgO or Ag3PO4 effectively diminishes the degree of supercooling in the THF hydrate formation.
AB - Generally, supercooling as large as about 25 K is necessary to form tetrahydrofuran clathrate hydrate (THF hydrate). In the present study, we have investigated how the existence of various additives affects the degree of supercooling (ΔT) in the THF hydrate formation without any external stimulus. The addition of either AgO or Ag3PO4 yields the best ΔT suppression, where ΔT was approximately 4 K, much smaller than 25 K. Raman spectra reveal that, in the supercooled THF aqueous solution with AgO before crystallization, the THF molecule forms a coordination bond with AgO, whereas it forms a hydrogen bond with a water molecule in the system without AgO. The oxygen atom of the THF molecules, which is a hydrogen-bonding site, was oriented to a AgO molecule in the aqueous solution. The orientation and the subsequent interruption of the hydrogen bond make it easy to form a hydration shell around the THF molecule. Scanning Transmission Electron Microscopy images by using the freeze-fracture replica method reveal that a cluster, which is the smallest structural unit of a crystal, includes Ag-containing nanoparticles formed from AgO or Ag3PO4, which accelerate the cluster formation. As a result, the addition of AgO or Ag3PO4 effectively diminishes the degree of supercooling in the THF hydrate formation.
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U2 - 10.1039/d2ce00645f
DO - 10.1039/d2ce00645f
M3 - Article
AN - SCOPUS:85139400054
SN - 1466-8033
VL - 24
SP - 6730
EP - 6738
JO - CrystEngComm
JF - CrystEngComm
IS - 38
ER -