On the process of oxidative dehydrodimerization of methane into C2-hydrocarbons on binary bismuth-containing catalysts

Abstract

Direct conversion of methane, the main component of natural gas, into more valuable C2 hydrocarbons (ethane and ethylene) opens up significant opportunities for natural gas utilization. This article explores the potential of binary bismuth-containing catalysts in the oxidative dehydrodimerization of methane. Bismuth's ability to activate methane and promote the formation of C–C bonds makes it a promising catalytic material. Combining bismuth with another metal or oxide (e.g. molybdenum, vanadium, niobium) in a binary catalyst provides the opportunity to increase activity and selectivity towards C2 products. This review discusses key aspects of this approach, including the reaction mechanism, the role of the bismuth moiety and cocatalyst, and the challenges associated with controlling product selectivity and catalyst stability. Several bismuth-containing binary oxides Bi–M (M = Mn, Al, Pb, Sr, Ti, Zr, Sn, W) have been studied at 730°C as the catalysts for the industrially promising reaction of oxidative dehydrodimerization of methane into ethane and ethane. Phase composition of most efficient of them (Bi–Mn, Bi–Pb, Bi–Al) was investigated by XRD; the nature of their catalytically active components was revealed. The binary oxide systems studied in this work were prepared by the thermal decomposition of coprecipitated metal hydroxides. The starting compounds were mainly metal nitrate salts, in the case of titanium and tin – chlorides, and in the synthesis of tungsten-containing contact – ammonium paratungstate. The practically valuable yields of the aimed C2-hydrocarbons (~20–22%) at the methane conversion of 47% and total selectivity to ethane and ethane of 47–48% were reached by means of the insertion of small amounts of alkali metal oxides, especially Li, into Bi–Mn oxide