Abstract
Supported lead oxide catalysts were prepared by using ${\alpha}-,{\beta}-{\gamma}$-alumina, and MgO as a support. Among the supported lead oxide catalysts, MgO-supported catalyst showed the highest $C_2^+$ hydrocarbon selectivity for the methane conversion into $C_2^+$ hydrocarbons, but ${\gamma}$-alumina-supported PbO catalyst gave the highest $CO_2$ selectivity. And ${\alpha}$-alumina-supported catlyst showed the midium activity, whereas ${\beta}$-alumina-supported catalyst gave little activity. These reaction characteristics seemed to be largely dependent on the acticity of lattice oxygens in supported catalysts, which would be influnto be largely dependent on the activity of lattice oxygens in supported catalysts, which would be influenced in the interaction between the supports and lead oxides and the properties of supports. Especially, much higher ration of (002)/(111) peak intensities for PbO phase on MgO support than on the other supports in X-ray diffraction analysis was considered to be ab evidence that methane oxidative coupling of methane might be so-called structure-sensitive reaction, and this seemed to be an example of surface oxide-support interaction (SOSI) in the oxidative coupling reaction.
${\alpha}-{\beta}-,{\gamma}$-알루미나 및 MgO를 담체로 사용하여 담지된 납산화물 촉매를 제조하였다. 담지된 납산화물 촉매상에서 메탄의 $C^{2+}$ 탄화수소로의 전환반응은 MgO 담지촉매에서 $C^{2+}$ 선택도가 최대로 얻어졌으며, ${\gamma}$-알루미나 담지 PbO 촉매에서는 $CO_2$ 선택도가 높았다. 그리고 ${\alpha}$-알루미나 담지촉매에서는 중간정도의 활성이 얻어졌으며, ${\beta}$-알루미나 담지촉매에서는 활성이 거의 나타나지 않았다. 이러한 반응특성은 촉매의 격자산소의 활성에 크게 의존하였으며, 또한 격자 산소의 활성은 담체와 산화물간의 상호작용과 담체의 성질에 영향받았다. 특히 MgO 담지 촉매에서는 X-선 회절분석에서 여타의 담체에서보다 PbO 산화물의 (002)면의 피크 세기가 (111)면의 세기에 비해 훨씬 크게 나타난 것으로 볼 때 메탄의 Oxidative Coupling 반응에서의 표면산화물-담체 상호작용(SOSI)의 한 예로 여겨졌다.
