전이금속 산화물이 담지된 모더나이트상에서의 메탄 산화반응

길준호; 이창용; 하백현

HWAHAK KONGHAK, Vol.29, No.1, 42-48, February, 1991

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전이금속 산화물이 담지된 모더나이트상에서의 메탄 산화반응

Methane Oxidation on Oxides of Transition Metals on Mordenite

길준호, 이창용, 하백현

초록

알루미늄 추출 모더나이트(SiO₂/Al₂O₃=22)에 동, 크롬, 니켈 그리고 코발트를 단독 또는 두 종을 혼합 함침시킨 후 500℃와 750℃에서 각각 환원ㆍ산화처리하여 산화촉매를 제조하고 메탄의 연소반응을 실시하였다. 이들 시료를 X선 회절분석한 결과, 담지한 금속은 환원ㆍ산화처리 후에는 대부분 20-30nm정도 크기의 CuO, Cr₂O₃, NiO 및 Co₃O₄ 등의 산화물로 분산되었다. 일반적으로 750℃에서 환원ㆍ산화처리하면 500℃에서 처리한 것에 비하여 모더나이트의 결정성이 저하되었지만 크롬이 첨가되면 모더나이트 결정성이 향상되었다. 이러한 안정성의 증가는 함침시 그리고 산화시 생성된 구조 내 크롬이온의 효과로 생각된다. 혼합물의 담지에서는 두 종의 금 속의 결합산화물은 XRD 분석으로는 관찰할 수 없었다. 메탄의 산화활성은 500℃에서 환원ㆍ산화처리한 시료에서는 동>크롬>코발트, 니켈이 담지된 순으로 활성을 나타내었다. 두 종의 혼합 담지된 경우도 활성은 동함량의 수준 정도로 나타났으며 750℃에서 환원ㆍ산화처리시는 동의작용에 의한 모더나이트의 결정성 감소로 담지되는 동 이온의 감소 및 CuO 결정의 크기의 성장으로 인하여 활성이 저하하였지만 크롬을 첨가함에 의하여 이런 점이 개선되어 활성이 향상되었다.

Combustion oxidation catalysts were prepared by impregnation of oxides of copper, chrome, nickel and cobalt on aluminum-deficient mordenites(SiO₂/Al₂O₃=22), which were redox-treated in reduc-tion/oxidation atmosphere at 500℃ and 750℃, respectively. For these catalysts methane combustion was carried out. X-ray diffraction analysis indicates that the metal oxides were dispersed with the av-erage particle size of about 20-30nm in the form of CuO, Cr₂O₃, Co₃O₄ and NiO. Redox-treated in reduc-tion/oxidation atmosphere at 750℃ reduced the crystallinity of the mordenite, but chrome addition im-proved the stability. This improvement in stability may be explained with the effect of remaining chrome ions in the mordenite pores which is formed when impregnating iits salt as well as reoxidation pretreat-ment. On the catalysts containing two kinds of metal oxides, XRD study informs that the oxides were dipersed individually without formation of new oxide compounds. The catalytic activities for 500℃ were appeared as the following order; CuO/DM>Cr₂O₃/DM>Co₃O₄/DM, NiO/DM. However catalytic activi-ties for the catalysts redox-treated at 750℃ was much reduced compared with the activities at 500℃, which is also explained with the reduction of mordenite crystallinity which makes the reducton of metal ion concentration and also of copper oxide particle size.

[References]

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Dwyer FG, Catal. Rev.-Sci. Eng., 6, 261 (1972)
Cullis CF, Willatt BM, J. Catal., 83, 267 (1983)
Kato A, Yamashita H, Matsuda S, "Successful Design of Catalyst," by Inui. T., Elsevier Science Pub., Amsterdam (1988)
Lovishegedus L, Summers JC, Schlatter JC, Baron K, J. Catal., 56, 321 (1979)
Arai H, Yamada T, Eguchi K, Seiyama T, Appl. Catal., 26, 265 (1986)
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Brrigs WS, Stover WA, Handerson DS, U.S. Patent, 3,288,558, November 29 (1966)
Fletcher P, Lower PR, Townsent RP, Spec. Publ. Chem. Soc., 33, 353 (1980)
Takahashi N, Saito M, Nagumo M, Mijin A, Zeolites, 6, 420 (1986)
Rutham R, Sanders MK, J. Catal., 27, 287 (1972)
Richard WO, Rollmann LD, Inorg. Chem., 16, 651 (1977)
Hurst NW, Gentry SJ, Jones A, Catal. Rev.-Sci. Eng., 24, 233 (1982)
Choi KY, Ph.D. Thesis, Hanyang Univ., Seoul, Korea (1989)
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Miro EE, Lombardo EA, Petunchi J, J. Catal., 104, 176 (1987)
Lee CY, Ha BH, in preparation (1988)
Tvaruskova Z, Bozacek V, Collection Czech. Chem. Comm., 45, 2479 (1980)
Goupil JM, Hemiduy JF, Cornet D, Zeolites, 2, 47 (1982)
Moroz EM, Bulusheva VS, Ushakov UA, Tsybulya SV, React. Kinet. Catal. Lett., 33, 185 (1987)

[Referenced By]

[1] Mannion WA, Cohn JG, Thompson CE, Mooney JJ, "Catalysts for the Control of Automotive Pollutants," p. 1 (1975)

[2] Dwyer FG, Catal. Rev.-Sci. Eng., 6, 261 (1972)

[3] Cullis CF, Willatt BM, J. Catal., 83, 267 (1983)

[4] Kato A, Yamashita H, Matsuda S, "Successful Design of Catalyst," by Inui. T., Elsevier Science Pub., Amsterdam (1988)

[5] Lovishegedus L, Summers JC, Schlatter JC, Baron K, J. Catal., 56, 321 (1979)

[6] Arai H, Yamada T, Eguchi K, Seiyama T, Appl. Catal., 26, 265 (1986)

[7] Innes WB, U.S. Patent, 3,438,721, April 15 (1969)

[8] Brrigs WS, Stover WA, Handerson DS, U.S. Patent, 3,288,558, November 29 (1966)

[9] Fletcher P, Lower PR, Townsent RP, Spec. Publ. Chem. Soc., 33, 353 (1980)

[10] Takahashi N, Saito M, Nagumo M, Mijin A, Zeolites, 6, 420 (1986)

[11] Rutham R, Sanders MK, J. Catal., 27, 287 (1972)

[12] Richard WO, Rollmann LD, Inorg. Chem., 16, 651 (1977)

[13] Hurst NW, Gentry SJ, Jones A, Catal. Rev.-Sci. Eng., 24, 233 (1982)

[14] Choi KY, Ph.D. Thesis, Hanyang Univ., Seoul, Korea (1989)

[15] Park HC, Lee YS, Ha BH, HWAHAK KONGHAK, 26(1), 7 (1988)

[16] Miro EE, Lombardo EA, Petunchi J, J. Catal., 104, 176 (1987)

[17] Lee CY, Ha BH, in preparation (1988)

[18] Tvaruskova Z, Bozacek V, Collection Czech. Chem. Comm., 45, 2479 (1980)

[19] Goupil JM, Hemiduy JF, Cornet D, Zeolites, 2, 47 (1982)

[20] Moroz EM, Bulusheva VS, Ushakov UA, Tsybulya SV, React. Kinet. Catal. Lett., 33, 185 (1987)