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18.97.14.89
18.97.14.89
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Surface Structure of Mo / H - ZSM5 Catalyst for CH4 Activation
Young Ho Kim, Richard W . Borry 3, Enrique Iglesia
응용화학 vol. 3 iss. 1 368-371(4pages)
UCI I410-ECN-0102-2008-570-001225415
This article is 4 pages or less.

Mo/H-ZSM5(0-8wt% Mo) catalysts for CH, aromatization were prepared from physical mixtures of MoO₃ and H-ZSM5. Surface diffusion of MoO_x species occurs at 623 K, and migration continues outside ZSM5 crystallites up to 773 K. If the Mo loading is higher than that which forms a single layer of MoO_x on the external surface of zeolite, Mo will be lost via sublimation of (MoO₃)_n oligomers or will destroy the ZSM5 framework by extracting Al to form inactive Al₂(MoO₄)₃ domains. Between 773-973 K, gas-phase transport of Mo also becomes important as Mo migrates inside zeolite channels, exchanges at acid sites and condenses to produce H₂O. Loss of H as H₂O during catalyst preparation and titration of remaining H^+ sites indicates exchange of one H per Mo added to H-ZSM5, consistent with a proposed structure of (Mo₂O_5)^+2 ditetrahedra located at two cation exchange sites.

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