Non-oxidative methane conversion over gold modified platinum-alumina catalysts.

Bimetallic catalysts Au-Pt/γ-Al2O3 were synthesized by wetness co-impregnation of alumina with aqueous solutions of H2PtCl6 and HAuCl4 in the presence of competing acids (HCl and CH3COOH). The platinum content in the samples was ∼ 0.5 wt.%, gold content was varied from 0.12 to 0.30 wt.%. The introduction of gold into catalyst Pt/γ- Al2O3 does not lead to a significant change in the qualitative and quantitative composition of Lewis acid sites of alumina. According to the transmission electron microscopy the average platinum particles size is 1.2 nm on the platinum-alumina catalyst surface. Conglomerates 6-30 nm in size are present on the surface of catalyst Au-Pt/γ-Al2O3 with gold content 0.30 wt.%. The modification of the platinum-alumina catalyst with gold leads to a decrease in the electron deficiency and dispersion of platinum. The quantity of chemisorbed methane on modified catalysts in two times less than on the surface of the platinum-alumina catalyst. It is connected to decrease in dispersion and electron deficiency of platinum. Catalysts Au-Pt/γ-Al2O3 were studied in the non-oxidative co-conversion of activated methane forms with n-pentane at 823 K. The modification of the Pt/γ-Al2O3 catalyst with gold leads to a decrease in the yield of aromatic hydrocarbons (benzene and toluene) from 22.2 to 16.4 wt.%. [ABSTRACT FROM AUTHOR]