Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Synthesis of Ceria Nanoparticles Using Supercritical Methanol with Various Surface Modifiers

초임계 메탄올을 이용한 표면개질된 세리아 나노입자의 합성

  • Ahn, Ki Ho (School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University) ;
  • Shin, Nae-Chul (School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University) ;
  • Kim, Minsoo (School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University) ;
  • Youn, Yong-Suk (School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University) ;
  • Hong, Giyoung (School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University) ;
  • Lee, Youn-Woo (School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University)
  • 안기호 (서울대학교 공과대학 화학생물공학부, 화학공정신기술 연구소) ;
  • 신내철 (서울대학교 공과대학 화학생물공학부, 화학공정신기술 연구소) ;
  • 김민수 (서울대학교 공과대학 화학생물공학부, 화학공정신기술 연구소) ;
  • 윤용석 (서울대학교 공과대학 화학생물공학부, 화학공정신기술 연구소) ;
  • 홍기영 (서울대학교 공과대학 화학생물공학부, 화학공정신기술 연구소) ;
  • 이윤우 (서울대학교 공과대학 화학생물공학부, 화학공정신기술 연구소)
  • Received : 2012.01.31
  • Accepted : 2012.03.22
  • Published : 2012.08.01
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Abstract

Ceria is one of the most important catalytic materials which can be used in three-way catalysts, waste water treatment, petroleum refining, etc. So far, many methods have been studied to produce ceria nanoparticles. In this study, ceria nanoparticles were prepared via solvothermal synthesis using supercritical methanol in short reaction time using a batch reactor. The size of synthesized ceria nanoparticles in supercritical methanol is 6 nm without capping agent, which is smaller than that made in supercritical water at the same conditions of $400^{\circ}C$ and 30 MPa. Size difference results from density and critical point difference between water and methanol and slow reaction rate at the surface of ceria particles in supercritical methanol which reduces crystal growth rate. Several organic compounds were added to modify the surface of ceria nanoparticles, and in-situ surface modification was confirmed by FT-IR and TGA analysis. Surface modified ceria nanoparticles have excellent dispersibility in organic solvent. Size and shape of surface modified ceria particles can be controlled by adjusting molar ratio of modifier to precursor and selection of modifier.

세리아 미세입자는 자동차, 석유공정, 폐수처리 등 다양한 분야에서 촉매로서 널리 쓰이고 있는 중요한 물질이다. 이제까지, 세리아 미세입자를 제조하기 위한 다양한 제조법이 연구되었는데, 본 연구에서는 짧은 반응시간과 간단한 공정이 가능한 초임계 메탄올을 이용하는 입자 제조 공정을 통해 세리아 나노입자를 제조하였다. 회분식 반응기를 이용하여 짧은 시간 안에 세리아 나노입자를 제조하는데 성공하였다. 초임계 메탄올을 이용하여 세리아 나노입자를 제조하는 경우, 다른 첨가제 없이도 약 6 nm의 크기를 갖는 나노입자를 합성할 수 있었다. 이 크기는 같은 온도와 압력조건의 초임계수를 이용하여 표면개질제 없이 합성한 입자보다 훨씬 작은 크기이다. 이는 초임계수와 초임계 메탄올의 밀도 차이와, 초임계 메탄올에서의 세리아 표면에서 일어나는 결정성장을 제한하는 반응, 그리고 초임계 메탄올과 초임계수의 임계점의 차이에서 기인하는 것이다. 또한 여러 가지 유기물을 표면개질제로 첨가하여 표면을 개질한 세리아 나노입자를 제조하였으며, FT-IR과 HR-TEM, TGA를 통해 이를 확인할 수 있었다. 표면을 개질한 세리아 나노입자는 표면개질을 하지 않은 세리아 나노입자와는 다르게, 유기용매에 대한 분산성이 뛰어났으며, 표면개질제로 사용하는 유기물의 양과 종류를 조절함으로써 세리아 나노입자의 크기와 모양을 조절할 수 있었다.

Keywords

References

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