Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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A Comparison of Structural Characterization of Composite Alumina Powder Prepared by Sol-Gel Method According to the Promoters

졸-겔법으로 제조된 복합 알루미나 미분체의 첨가제에 의한 구조적 특성 비교

  • Lee, Jung-Woon (Department of Chemical Engineering, Sogang University) ;
  • Yoon, Ho-Sung (Division of Minerals Utilization and Materials, Korea Institute of Geoscience and Mineral Resources) ;
  • Chae, U-Suk (Department of Chemical Engineering, Sogang University) ;
  • Park, Han-Jin (Department of Chemical Engineering, Sogang University) ;
  • Hwang, Un-Yeon (Department of Chemical Engineering, Sogang University) ;
  • Park, Hyung-Sang (Department of Chemical Engineering, Sogang University) ;
  • Park, Dal-Ryung (LNG Technology Research Center, KOGAS) ;
  • Yoo, Seung-Joon (Faculty of Environmental and Chemical Engineering, Seonam University)
  • 이정운 (서강대학교 화학공학과) ;
  • 윤호성 (한국지질자원연구원 자원활용연구부) ;
  • 채의석 (서강대학교 화학공학과) ;
  • 박한진 (서강대학교 화학공학과) ;
  • 황운연 (서강대학교 화학공학과) ;
  • 박형상 (서강대학교 화학공학과) ;
  • 박달령 (한국가스공사 연구개발원 LNG기술연구센타) ;
  • 유승준 (서남대학교 환경화학공학부)
  • Received : 2004.12.27
  • Accepted : 2005.06.13
  • Published : 2005.08.31
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Abstract

In this research, composite alumina was prepared to add the various promoters by sol-gel method and examined its thermal stability. After sintering at $1,200^{\circ}C$, the thermal stability resulted in following order, $Si{\fallingdotseq}La$ > Ti > $Ba{\fallingdotseq}Ce$ > Y > $Zr{\fallingdotseq}Mg$, in accordance with adding the promoters. Especially in case of silica-added alumina, a phase transformation temperature to ${\alpha}$-alumina increased about $150^{\circ}C$ and after sintering at $1,200^{\circ}C$, it showed to maintain in ${\gamma}$-form and ${\delta}$-form alumina phase. Also it showed an increase of surface area from $3m^2/g$ to $71m^2/g$ compared with pure ${\alpha}$-alumina. In the case of silicaadded alumina, the characterization change of this alumina particle resulted in a delay of phase transformation because Si-O-Al bond was increased when sintered at high temperature. In case of lanthanum-added alumina, there was a sintering delay phenomenon in inter-particles as $LaAlO_3$ structure existed. The existence of lanthanum structure was confirmed by XRD and XPS analysis. It appeared on the alumina surface as $La_2O_3$ structure when it was sintered under $1,000^{\circ}C$, as the perovskite structure of $LaAlO_3$ at above $1,000^{\circ}C$ and as the magneto-plumbite structure of $LaAl_{11}O_{18}$ at above $1,300^{\circ}C$.

본 연구는 졸-겔법을 이용하여 복합 알루미나를 제조하였고, 다양한 첨가제의 첨가에 의한 복합 알루미나의 열적 안정성을 고찰하였다. $1,200^{\circ}C$에서 소성시킨 복합 알루미나의 열적 안정성은 사용된 첨가제에 따라서 $Si{\fallingdotseq}La$ > Ti > $Ba{\fallingdotseq}Ce$ > Y > $Zr{\fallingdotseq}Mg$ 순으로 나타났다. 특히 실리카 첨가시 ${\alpha}$-알루미나로의 상전이 온도를 $150^{\circ}C$이상 높여 $1,200^{\circ}C$에서 소성 후에도 ${\gamma}$-형에서 ${\delta}$-형의 알루미나 상을 유지함을 알 수 있었고, 비표면적이 $3m^2/g$인 ${\alpha}$-알루미나에 비해 $71m^2/g$(비표면적) 범위까지 증가됨을 보였다. 이러한 알루미나 입자의 특성변화는 실리카 첨가 알루미나의 경우 고온으로 소성시 Si-O-Al의 결합의 증가로 인하여 알루미나의 상전이를 지연시키는 결과로 나타나고, 란타늄 첨가 알루미나의 경우 $LaAlO_3$ 구조의 존재로 인해 알루미나의 입자간 소결을 지연시킴을 알 수 있었다. 또한 란타늄 첨가시 $1,000^{\circ}C$ 이하에서 소성시킨 경우 란타늄이 알루미나 표면에 $La_2O_3$ 구조로 존재하나 $1,000^{\circ}C$ 이상에서는 $LaAlO_3$의 perovskite 구조로 존재하고, $1,300^{\circ}C$ 이상에서는 $LaAl_{11}O_{18}$의 magneto-plumbite 구조로 존재함을 XRD와 XPS 분석 결과에 의해 확인할 수 있었다.

Keywords

Acknowledgement

Supported by : 에너지관리공단

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