알칼리조촉매를 사용한 Zn-Oxide 담지 촉매상에서 메탄의 Oxidative Coupling 반응특성

김상채; 유의연

HWAHAK KONGHAK, Vol.28, No.5, 536-546, October, 1990

Export Citation

알칼리조촉매를 사용한 Zn-Oxide 담지 촉매상에서 메탄의 Oxidative Coupling 반응특성

The Oxidative Coupling of Methane over Supported Zine Oxide Catalyst with Alkali Promotes

김상채, 유의연

초록

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 O₂^2-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(O₂^2- or O₂^-)on the surface. The activation energy was ca. 39kcal/mole.

[References]

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[Referenced By]

[1] Lee JS, Oyama ST, Catal. Rev.-Sci. Eng., 30, 249 (1988)

[2] Anderson JR, Appl. Catal., 47, 177 (1989)

[3] Pitchai R, Klier K, Catal. Rev.-Sci. Eng., 28(1), 13 (1986)

[4] Agarwal SK, Migone RA, Marcelin G, Appl. Catal., 53, 71 (1989)

[5] Martin GA, Bates A, Ducarme V, Mirodates C, Appl. Catal., 47, 287 (1989)

[6] Lo MY, Agarwal SK, Marcelin G, J. Catal., 112, 168 (1988)

[7] Roos JA, Korf SJ, Veehof RHJ, Vanommen JG, Ross JRH, Appl. Catal., 52, 131 (1989)

[8] Otsuka K, Liu Q, Hatano M, Morikawa A, Chem. Lett., 903 (1986)

[9] Lane GS, Wolf EE, Proc. 9th Int. Congr. Catal., 2, 944 (1988)

[10] Ito T, Lunsford JH, Nature, 311, 721 (1985)

[11] Yamagata N, Tanaka K, Sasaki S, Okazaki S, Chem. Lett., 81 (1987)

[12] Otsuka K, Jinno K, Morikawa A, J. Catal., 100, 353 (1986)

[13] Keller GE, Bhasin MM, J. Catal., 73, 9 (1982)

[14] Hinsen VW, Baerns M, Chem. Ztg., 107, 223 (1983)

[15] Otsuka K, Hatano M, Komatsu T, Bibby DM, "Methane Conversion," Elsevier, Amsterdam, 383 (1988)

[16] Aika K, Lunsford JH, J. Phys. Chem., 81, 1393 (1977)

[17] Ohtsuka Y, Kuwabara M, Tomita A, Appl. Catal., 47, 307 (1989)

[18] Anshits AG, Sokolovskii VD, React. Kinet. Catal. Lett., 37, 397 (1988)

[19] Zhang HS, Wang JX, Driscoll DJ, Lunsford JH, J. Catal., 112, 366 (1988)

[20] Ito T, Wang JH, Lin CH, Lunsford JH, J. Am. Chem. Soc., 107, 5062 (1985)

[21] Satterfield CN, "Heterogeneous Catalysis in Practice," 1st ed., McGraw-Hill, New York, p. 126 (1980)

[22] Otsuka K, Liu Q, Morikawa A, Inorg. Chem. Acta, 118, L23 (1986)

[23] Hinsen W, Bytyn W, Baerns M, Proc. 8th Int. Congr. Catal., Vol. 3, Dechema, Frankfurt am Main, p. 581 (1984)

[24] Weissman M, Benson SW, Int. J. Chem. Kinet., 16, 307 (1984)

[25] Dean JA, "Langes's Handbook of Chemistry," 12th ed., McGraw-Hill, New York (1979)

[26] Driscoll DJ, Martir W, Wang JX, Lunsford JH, J. Am. Chem. Soc., 107, 58 (1985)

[27] Otsuka K, Jinno K, Inorg. Chim. Acta, 121, 237 (1986)