Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Synthesis of LSX Zeolite and Characterization for Nitrogen Adsorption

LSX 제올라이트의 합성 및 질소 흡착 특성

  • Hong, Seung Tae (Department of Chemical & Biomolecular Engineering, Sogang University) ;
  • Lee, Jung-Woon (Department of Chemical & Biomolecular Engineering, Sogang University) ;
  • Hong, Hyung Phyo (Technical R & D Center, DONGWOO FINE-CHEM CO., LTD) ;
  • Yoo, Seung-Joon (Department of Chemical Engineering, Seonam University) ;
  • Lim, Jong Sung (Department of Chemical & Biomolecular Engineering, Sogang University) ;
  • Yoo, Ki-Pung (Department of Chemical & Biomolecular Engineering, Sogang University) ;
  • Park, Hyung Sang (Department of Chemical & Biomolecular Engineering, Sogang University)
  • 홍승태 (서강대학교 화공생명공학과) ;
  • 이정운 (서강대학교 화공생명공학과) ;
  • 홍형표 (동우 화인켐 주식회사 기술연구소) ;
  • 유승준 (서남대학교 화학공학과) ;
  • 임종성 (서강대학교 화공생명공학과) ;
  • 유기풍 (서강대학교 화공생명공학과) ;
  • 박형상 (서강대학교 화공생명공학과)
  • Received : 2006.08.25
  • Accepted : 2006.11.23
  • Published : 2007.04.30
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Abstract

The synthesis and the characterization of Low Silica X (LSX) zeolite for nitrogen adsorption have been studied. The performance of LSX zeolite for nitrogen adsorption was compared to that of the commercial zeolite. The $Na_2O/(Na_2O+K_2O)$ ratio in the gel and the crystallization time were fixed as the synthetic factor. The LSX zeolite was formed at the $Na_2O/(Na_2O+K_2O)$ ratio of 0.75. The formation of LSX zeolite was confirmed by XRD and SEM. The Si/Al ratio was investigated by using XRF and FT-IR. The synthesized LSX zeolite showed a lower Si/Al ratio than the NaY and NaX zeolites although they have a same faujasite structure. The Si/Al ratio of the LSX zeolite converged close to 1. 1A (Li, Na, K) and 2A (Mg, Ca, Ba) group elements were ion-exchanged to the LSX zeolite. As the charge density of cation rises, the amount of nitrogen adsorbed increased. $Li^+$ ion-exchanged LSX zeolite showed the highest nitrogen adsorption weight. When the Li/Al ratio was over 0.65, nitrogen adsorption increased remarkably. $Li^+$ ions located on the supercage (site III, III') in the LSX zeolite played a role as nitrogen adsorption sites. When the $Ca^{2+}$ ions were added to the LiLSX zeolite by ion-exchange method, the performance for nitrogen adsorption increased more. The performance for the nitrogen adsorption was the highest at the Ca/Al ratio of 0.26. Nitrogen adsorption capacity of LiCaLSX (Ca/Al=0.26) zeolite was superior to the commercial NaX zeolite.

Low Silica X (LSX) 제올라이트를 합성하여 질소 흡착 반응에 적용하였으며, 기존의 상용화된 질소흡착용 제올라이트와 질소 흡착 성능 및 그 특성을 비교하였다. LSX 제올라이트의 제조 변수로 젤 상태에서의 $Na_2O/(Na_2O+K_2O)$비와 결정화 시간을 고려하였다. $Na_2O/(Na_2O+K_2O)$ 비가 0.75일 때 LSX 제올라이트가 합성됨을 XRD, SEM 분석으로부터 확인하였다. 합성된 LSX 제올라이트는 같은 faujasite 구조를 갖는 NaY나 NaX 제올라이트보다 Si/Al 비가 작고 거의 1에 수렴함을 XRF와 FT-IR 결과로부터 확인하였다. 1A(Li, Na, K), 2A(Mg, Ca, Ba) 족 양이온으로 교환된 LSX 제올라이트에 대해 질소 흡착 테스트를 수행한 결과, 양이온의 전하밀도가 증가할수록 질소 흡착량이 증가하였으며, LiLSX의 경우 질소 흡착량이 가장 많았다. LiLSX의 $Li^+$ 이온 함량을 변화시켜 가며 질소 흡착량을 측정한 결과 Li/Al 비가 0.65 이상일 때, 질소 흡착량이 급격히 증가하였다. $Li^+$ 이온은 제올라이트 세공 내의 supercage(site III, III') 에 위치할 때, 질소 흡착점의 역할을 하였다. LiLSX 제올라이트에 $Ca^{2+}$ 이온을 이온교환시킨 결과 질소 흡착 성능이 더 향상되었는데, Ca/Al의 비가 0.26일 때 질소 흡착 성능이 가장 좋았다. LiCaLSX(Ca/Al=0.26) 제올라이트는 기존의 상용 NaX 제올라이트보다 질소 흡착 성능이 우수하였다.

Keywords

Acknowledgement

Supported by : 서강대학교 산업기술연구소

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