Nonoxidative coupling of ethane with gold loaded photocatalysts

Abstract

Direct and continuous conversion of ethane to yield n-butane and hydrogen at near room temperature (ca. 320 K) was examined with gold loaded gallium oxide and titanium dioxide photocatalysts without the aid of any oxidant in a flow reactor. A Ga₂O₃ photocatalyst produced n-butane and ethene as well as hydrogen with an almost stoichiometric ratio of products from ethane. Loading Au on the Ga₂O₃ sample gave a 12 times higher production rate of n-butane such as 0.65 μmol h⁻¹ with a high selectivity of 89%. Although a bare TiO₂ sample showed very low yield due to poor reduction resistance, the addition of an Au cocatalyst drastically improved the photocatalytic performance of the TiO₂ sample, i.e., the Au(0.2)/TiO₂ sample produced n-butane and ethene continuously at least for 5 h, where the production rate of n-butane, the n-butane selectivity, and the apparent quantum efficiency (AQE) for n-butane formation were 0.92 μmol h⁻¹, 92%, and 0.02%, respectively. The reaction mechanism of n-butane formation as the main reaction was proposed to be the photocatalytic nonoxidative coupling of ethane (NOCE), which is similar to the photocatalytic nonoxidative coupling of methane (NOCM).