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Search / Korean Journal of Chemical Engineering
HWAHAK KONGHAK,
Vol.30, No.1, 1-8, 1992
Ge(OCH3)4의 화학증착에 의한 HZSM-5 촉매의 형상선택성에 관한 연구
On the Shape Selectivity of HZSM-5 Catalyst by Ge(OCH3)4-CVD Method
문세기, 김형진, 김문혁, 손영순
300℃, 2×10-3 torr 진공하에서 germanium methoxide[Ge(OCH3)4]를 증착한 후, 400℃ 대기 중에서 소성하여 germanium oxide가 증착된 제올라이트(GeHZSM-5)를 제조하였다. 제조된 촉매는 암모니아 승온탈착법과 water, p-xylene, o-xylene 등의 흡착실험 침 IR 분석을 수행하여 특성을 분석하였다. 증착된 germanium oxide는 촉매의 내부 산점 및 구조에 변화를 일으키지 않고, 외부표면상에서만 증착되어, HZSM-5 촉매의 pore-opening size를 미세하게 조절하는 역할을 하는 것으로 추측된다. 이러한 pore-opening size의 조절효과를 톨루엔(toluene)의 메탄올(methanol)에 의한 알킬화 반응을 행하여 확인하였다. 반응시의 주 생성물인 xylene isomer 중에서 가장 작은 kinetic diameter를 갖는 p-xylene의 수율은 증가하는 반면, m-, o-xylene의 수율은 감소하였다. 결론적으로, 증착된 germanium oxide의 역할은 HZSM-5 촉매의 pore-opening size를 미세하게 조절하여 HZSM-5 촉매의 형상선택성을 증가시키는 것으로 생각된다.
Germanium methoxide was deposited irreversively by CVD(chemical vapor deposition) on the zeolite(HZSM-5) under 2 TIMES 10-3 torr and at 300℃, and the deposited materials were calcined at 400℃ in air, finally forming germanium oxide-deposited zeolites(GeHZSM-5). These were characterized by tempera-ture-programmed desorptiion of ammonia, FT-IR analysis and adsorption experiments using water, p-xylene and o-xylene as adsorbates. It was suggested that the germanium oxide was deposited only on the external surface of the catalysts and narrowed the pore-opening size effectively without changing the internal structure and the acidity of the catalysts. The fine control of pore-opening size was tested by alkylation of toluene with methanol. Hydrocarbon product distribution shifted to smaller molecules over GeHZSM-5 than HZSM-5 catalyst;that is, the yields of m-, o-xylenes were decreased, but the yield of p-xylene was increased. Enhance-ment of the para-shape selectivity in xylene isomers indicated the fine control of the pore-opening size accord-ing to the deposition extent.
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참고문헌정보(참고문헌, 인용문헌)는 화학공학소재연구정보센터에 의해 제공되고 있습니다.