MoO<sub>3</sub> 촉매상에서의 메탄올 부분산화반응

김정희; 박윤석; 이호인

Journal of the Korean Industrial and Engineering Chemistry, Vol.2, No.2, 127-137, June, 1991

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MoO₃ 촉매상에서의 메탄올 부분산화반응

The Partial Oxidation of Methanol of MoO₃ Catalyst

김정희, 박윤석, 이호인

초록

고진공계에서의 열탈착실험을 통하여 MoO₃ 촉매상에서의 CH₃OH 분해 및 부분산화반응에 관한 연구를 수행하였다. CH₃OH는 촉매표면에 methoxy(-OCH₃)와 수소원자(-H)의 형태로 흡착되어 있다가 흡착수소원자가 methoxy 와 재결합하면서 425 K에서 CH₃OH로 탈착하였으며, methoxy로부터 수소원자가 떨어져 나가면서 545 K에서 HCHO가 탈착되었다. 이때 반응에 의해서 생성된 물은 428 K에서 탈착하는 α-피크와 586 K에서 탈착하는 β-피크를 보였으며, α-피크는 표면에 형성된 hydroxyl 에 기인하는 탈착피크, β-피크는 methoxy가 수소를 잃으면서 HCHO의 형태로 촉매표면에서 탈착하면서 남긴 표면수소원자와 격자산소가 반응하여 생성된 물에 각각 기인하는 것으로 보였다. 선흡착된 산소원자는 CH₃OH의 분해흡착을 촉진시킴으로써 CH₃OH의 흡착량을 감소시켰다.

The dissociation and partial oxidation of CH₃OH on polycrystalline MoO₃ powder catalyst were studied using thermal desorption spectrometry(TDS) under high vacuum condition. CH₃OH was dissociatively adsorbed on MoO₃ in the forms of surface methoxy(-OCH3) and atomic hydrogen(-H). CH₃OH desorbed at 425 K via the re-association of methoxy and adsorbed hydrogen atom, and HCHO desorbed at 545 K through the bond breakage of C-H in methoxy. Water TDS spectra showed two desorption peaks, that is, α-peak at 428 K and β-peak at 586 K. It was suggested that α-peak was due to the hydroxyl formed on MoO₃ surface during the dissociation of CH₃OH, and that β-peak was from the association of lattice oxygen and surface hydrogen atom formed by the bond breakage of C-H in methoxy. Pre-adsorbed oxygen on the surface of MoO₃ catalyst increased the amount of adsorption of CH₃OH by promoting the dissociation of CH₃OH on the surface, whereas pre-adsorbed water decreased the amount of adsorption of CH₃OH by blocking of adsorption sites for CH₃OH.

[References]

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[1] LePage JF, "Applied Heterogeneous Catalysis," Chap. 9, Editions Techniq., Paris (1986)

[2] Keim W, "Catalysis in C₁ Chemistry," D. Reidel Publishing Company, Dordrecht, p. 89 (1983)

[3] Sites AB, "Applied Industrial Catalysis," B.E. Leach(ed.), 2, Academic Press, New York, p. 138 (1983)

[4] Adkins H, Peterson WR, J. Am. Chem. Soc., 53, 512 (1931)

[5] Novakova J, Jiru P, Zavadil V, J. Catal., 17, 93 (1970)

[6] Novakova J, Kiru P, Zavadil V, J. Catal., 21, 143 (1971)

[7] Grzybowska B, Haber J, Janas J, J. Catal., 49, 150 (1977)

[8] Haber J, "Solid State Chemistry in Catalysis," R.K. Grasselli and J.F. Bradzil (Eds.), ACS., Washington, p. 3 (1985)

[9] Novakova J, Catal. Rev.-Sci. Eng., 4, 77 (1971)

[10] Groff RP, J. Catal., 86, 215 (1984)

[11] Yang TJ, Lunsford JH, J. Catal., 103, 55 (1987)

[12] Ohuchi F, Firment LE, Chowdhry U, Ferretti A, J. Vac. Sci. Technol. A, 2, 1022 (1984)

[13] Tatibouet JM, Germain JE, J. Catal., 72, 375 (1981)

[14] Tatibouet JM, Germain JE, Volta JL, J. Catal., 82, 240 (1983)

[15] Trifiro F, Notarbartolo S, Pasquon I, J. Catal., 22, 324 (1971)

[16] Allison JN, Golddard JA, J. Catal., 92, 127 (1985)

[17] Park YS, Lee HI, HWAHAK KONGHAK, 23(2), 79 (1985)

[18] Farneth WE, Staley RH, Sleight AW, J. Am. Chem. Soc., 108, 2327 (1986)

[19] Redhead PA, Vacuum, 12, 20 (1962)

[20] Golodets GI, "Studies in Surface Science and Catalysis," Vol. 15, "Heterogeneous Catalytic Reaction Involving Molecular Oxygen," Chap. XVI, Elsevier, Amsterdam (1983)

[21] Toyoshima I, Somorjai GA, Catal. Rev.-Sci. Eng., 19, 105 (1979)

[22] Pernicone N, Lazzerin F, Liberti G, Lanzavecchia G, J. Catal., 14, 293 (1969)