METHYLATION OF NAPHTHALENE BY METHANE OVER SUBSTITUTED ALUMINOPHOSPHATE MOLECULAR-SIEVES

The catalytic activity of substituted aluminophosphate molecular sieves, ElAPO-5 (El = Pb, Cu, Ni, and Si), in the activation of methane for direct methylation of naphthalene has been investigated at 400-degrees-C under elevated pressures of methane in an autoclave. In the presence of the as-synthesized catalysts, methylation of naphthalene was observed by gas chromatography and H-1 NMR spectroscopy. The major identified products in the methylation experiments were the two monomethylnaphthalenes together with small amounts of ethyl and dimethylated products and dinaphthalene. CuAPO-5, PbAPO-5, and SAPO-5 gave conversions of 15-16% in 1 h, whereas NiAPO-5 showed lower activity. Based on the naphthalene remaining, up to 21 % naphthalene conversion was obtained when a catalyst incorporating both Cu and Si was used.