121st General Meeting of the KCS

Type Poster Presentation
Area Material Chemistry
Room No. Event Hall
Time 4월 20일 (금요일) 11:00~12:30
Code MAT.P-356
Subject Specific surface area of layered double hydroxides according to synthesis method, calcination condition and reconstruction
Authors Bo-Kyung Kim, GYEONGHYEON GWAK1, Jae-Min OH2,*
Department of Chemistry, Yonsei University, Korea
1Beamline Research Division, Pohang Accelerator Laboratory, Korea
2Chemistry and Department of Medical Chemistry, Yonsei University, Korea
Abstract Specific surface area (SBET) of layered double hydroxides (LDHs) is important considering their application as catalysts, drug reservoir, pollutant scavenger and etc. We investigated SBET and porosity of LDHs which were synthesized through various methods, calcined at different temperature to obtain layered double oxides (LDOs) and reconstructed to original LDH structure. Three different synthesis methods were utilized to obtain pristine MgAl-CO3-LDHs: 1) coprecipitation of metal cations with sodium hydroxide (LDH-C), 2) coprecipitation followed by hydrothermal treatment (LDH-CH) and 3) coprecipitation of metal cations with homogeneous urea hydrolysis (LDH-U). All the LDHs were calcined at different temperature (400 ℃, 500 ℃ and 600 ℃) for 10 h, showing phase transformation to periclase (MgO, JCPDS No. 45-9846), a typical phase of LDO. The LDOs were successfully reconstructed to LDH phase in the presence of water and bicarbonate anion. We found that calcination and reconstruction process generally increased SBET values, where the synthesis method governed the overall values. The SBET values of pristine, calcined and reconstructed LDH were highly related to the crystallite size (X-ray diffraction pattern) and local disorder around Al (27Al-MASNMR). The highest SBET ~250 m2/g was obtained with calcined LDH synthesized by urea hydrolysis.
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