Oxidative decomposition of methanol in a vibroacoustic fluidized bed of Ag-coated cenosphere core-shell catalyst

Abstract

The paper presents results of a study of oxidative decomposition of methanol in a fl uidized bed of silver catalyst. The process of methanol oxidation was carried out on Ag-coated cenospheres core-shell catalyst. The catalyst was obtained by precipitation of silver from methanolic solution of silver nitrate on cenospheres. Cenospheres are lightweight, inert, hollow spheres, which can be easily introduced into a fl uidized bed. Application of the catalyst in a form of fl uidized bed should ensure good temperature equalization which is very important at low temperatures due to the possibility of generation of formaldehyde. It turned out that local hot points occur in that kind of a catalyst (in the form of a fl uidized bed but with very low density), thus use of additional acoustic wave is necessary to ensure good control over the temperature of the process. The products of the process of methanol oxidation were monitored on-line by Fourier transform infrared spectroscopy (FTIR). The catalyst has proven to be highly active in the oxidative decomposition of methanol. Full of methanol conversion in reaction of complete oxidation was achieved at 350 o C.

Catalytic oxidation of methanol in the cenospheric fluidized bed

“…S1231-S1240 S1233 locity of grains of the catalyst is reduced and the contact time between fluidising medium and grains is increased. Previous studies have shown that oxidation of methanol can be successfully carried out on Ag-coated cenospheres having a core-shell structure [41]. It turned out, however, that the silver deposited on aluminosilicate microsphere is not resistant to abrasion, which resulted in silver particles of the shell being removed from the fluidised bed.…”

“…The fluidisation process was supported by sounds emitter with a frequency of 45 Hz. It facilitated achieving the minimum fluidisation velocity at low flow speed of gas [40] and also prevented formation of channels in the bed, local areas of overheating of the catalyst [41]. Liquid methanol (2-18 cm 3 /h) and a solution of N 2 O (72 cm 3 /min.)…”