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HWAHAK KONGHAK,
Vol.28, No.5, 536-546, 1990
Vol.28, No.5, 536-546, 1990
알칼리조촉매를 사용한 Zn-Oxide 담지 촉매상에서 메탄의 Oxidative Coupling 반응특성
The Oxidative Coupling of Methane over Supported Zine Oxide Catalyst with Alkali Promotes
조성과 담체 및 알칼리조촉매를 달리한 Zn-Oxide 촉매상에서 메탄의 oxidative coupling 반응에 의한 에틸렌과 에탄의 합성반응을 연구하였다. 담지촉매의 산점은 에틸렌과 에탄의 선택도를 감소시켰으며, 산점이 나타나지 않은 Zn-Oxide/α-Al2O3촉매의 선택도가 우수하였고 Zn-Oxide의 최적 담지량은 60wt%일 때이었다. Zn-Oxide/α-Al2O3 촉매계에 할로겐족 원소가 함유된 알칼리금속 조촉매들을 첨가할 때의 활성순서는 NaBr>NaCl>NaI>NaF 로 나타났으며, 에틸렌의 생성에 Br과Cl 라디칼의 역할이 제시되었지만 NaF 및 알칼리금속염(NaNO3, Li2CO3, KNO3)은 부촉매의 역할을 하였다. NaCl(30wt%)/Zn-Oxide(60wt%)/α-Al2O3 촉매상에서 속도론적 고찰을 통하여, CH3 라디칼의 생성에 관여하는 산소종은 표면상의 이원자산소인 O22- 나 O2- 로 제시할 수 있었고, 활성화에너지는 약 39Kcal/mole 이었다.
The oxidative coupling of methane to ethylene and ethane was studied over Zn-Oxide catalysts with different compositions of catalysts, different supports and promoters. The selectivity for C2(C2H4+C2H6) decreased with an increase in the acid sites of supported catalysts. The Zn-Oxide/α-Al2O3 catalyst without acid sites showed that a good C2(C2H4+C2H6) selectivity. The optimal loading of Zn-Oxide was 60wt%. When alkali halide promoters were added to Zn-Oxide/α-Al2O3, the activity order was NaBr>NaCl>Nal>NaF. Br and Cl radicals might play an important role in formation of ethylene, but NaF and alkali metal salts(NaNO3, Li2CO3, KNO3)played a role of inhibitor. From kinetic studies on oxidative coupling of methane over NaCl(30wt%)/Zn-Oxide(60wt%)/α-Al2O3, the oxygen species responsible for formation of CH3, radical was suggested to be diatomic oxygen(O22- or O2-)on the surface. The activation energy was ca. 39kcal/mole.
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