Under optimum conditions, Cu*+-exchanged FeZSM5 catalyses the oxidation of methane by nitrous oxide with high selectivity for methanol production. H+-Exchanged FeZSM yields mainly carbon oxides.At low conversions (0.1-2.7%) the zeolite H-ZSMS catalyses oxidation of methane by nitrous oxide to appreciable amounts of methanol, formaldehyde, C2 + C3 olefins, and Cb-C12 aromatic products, although carbon oxides still constitute at least two-thirds of the carbon-containing product.1.2 Further-

Laser Raman spectra have been recorded of adsorbed poly(acety1ene) formed by the polymerization of acetylene on y-alumina and zeolite KX. Spectral evidence indicates that on both y-alumina and zeolite KX monomeric acetylene is physisorbed via its 7~ electron system in a '' side-on " orientation. The chain length of the polyene chains formed on y-alumina appear to increase with increasing activation temperature. The line intensities in the Raman spectra of the coloured polyenes are significantly enhanced by resonance effects. * Fig. l(u) shows the sample activated at 820K in which the band at 1962 cm-' can only just be observed.

Laser Raman spectra of Br, adsorbed on zeolites X, Y and A reveal features characteristic of physisorbed Br, and of Br, on cation oxide sites. Specifically, Br, on zeolites X adsorbs on sites 111 (v(Br-Br), 318-280 em-') and on sites I1 (u(Br-Br), 280-240 em-'). The data indicate that the cations in sites I1 are more effectively shielded by the oxide framework than those in sites 111. The greater participation of the oxide framework in the adsorption at sites I1 is also reflected in the detection of the adsorbate-adsorbent frequency, v(O...Br) at -160 cm-'. The appearance of this line is indicative of significant donor (oxide)-acceptor (bromine) electron-transfer interaction.The spectra of the adsorption complex NaY + Br, confirm the assignments for MX + Br, as NaY has no cations in sites I11 and fewer cations in sites I1 than NaX, with the result that only Br2 on sites I1 (271 cm-', Nay; 270 cm-', NaX) and physisorbed Br, is detected. For NaA, no ~( 0 . . .Br) is detected, which is consistent with the previously reported absence of charge-transfer interactions between the oxide framework and Br2.

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