HWAHAK KONGHAK, Vol.29, No.4, 440-447, August, 1991
은이온교환 L-type 제올라이트의 물리화학적 성질과 촉매활성
Physico-Chemical Properties and Catalytic Activity of Silver-Exchanged L-type Zeolite
초록
은이온교환 L-type 제올라이트의 물리화학적 성질과 산촉매반응의 촉매활성에 관하여 연구하였으며, 물리화학적 성질은 CO와 pyridine의 흡착에 대한 적외선 분광분석, X-선 회절분석, TPR 및 수소 흡착실험에 의하여 조사하였다. 수소로 환원된 AgL 제올라이트 촉매상에는 수소가 가역적으로 화학흡착되었으며, 수소의 흡착에 대한 활성점은 Agn+와 같은 silver cluster이었다. o-Xylene transformation에 대하여, 반응계내에 기상의 수소가 공존하면 AgL 제올라읕 촉매의 활성 증대효과가 관찰되었으며, 이 효과는 반응계내 수소의 공존여부에 따라 가역적이었다. 이러한 촉매활성의 증대효과는 다른 산촉매 반응에서도 관찰되었으며, 촉매상에 화학흡착된 수소는 proton의 형태로 존재함을 알 수 있다.
Physico-chemical properties and catalytic activity of silver exchanged L-type zeolite were studied by infrared spectroscopy of adsorbed CO and pyridine, X-ray diffactometry, TPR(temperature proprammed reduction), hydrogen adsorption and acid-catalyzed reactions. Hydrogen was chemisorbed reversibly on the reduced silver exchanged L-type zeolite, and the active site for the hydrogen adsorption was related to a silver cluster such as Agn+. For o-xylene transformation, the catalytic activity of AgL-48 in the presence of hydrogen was much higher than that of nitrogen alone as a carrier gas. This enhancing effect of hydrogen was reversible by the presence and the absence of gaseous hydrogen in the reaction system. This enhancing effect was also observed in the other acid-catalyzed reactions, and the chemisorbed hydrogen on the reduced AgL-48 zeolite was retained as acidic protons in the zeolite.
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