Photocatalytic Oxidative Coupling of Ethane to n-Butane Using CO2 as a Soft Oxidant over NiTi-Layered Double Hydroxide

Selective conversion of ethane (C2H6) to high-value-added chemicals is a very important chemical process, yet it remains challenging owing to the difficulty of ethane activation. Here, a NiTi-layered double hydroxide (NiTi-LDH) photocatalyst is reported for oxidative coupling of ethane to n-butane (n-C4H10) by using CO2 as an oxidant. Remarkably, the as-prepared NiTi-LDH exhibits a high selectivity for n-C4H10 (92.35%) with a production rate of 62.06 mu mol g(-1) h(-1) when the feed gas (CO2/C2H6) ratio is 2:8. The X-ray absorption fine structure (XAFS) and photoelectron characterizations demonstrate that NiTi-LDH possesses rich vacancies and high electron-hole separation efficiency, which can promote the coupling of C2H6 to n-C4H10. More importantly, density functional theory (DFT) calculations reveal that ethane is first activated on the oxygen vacancies of the catalyst surface, and the C-C coupling pathway is more favorable than the C-H cleavage to C2H4 or CH4, resulting in the high production rate and selectivity for n-C4H10.

Automated summary

A new NiTi-layered double hydroxide photocatalyst has been developed for the selective conversion of ethane to n-butane. The NiTi-LDH catalyst exhibits a high selectivity and production rate for n-butane, thanks to its rich vacancies and efficient electron-hole separation. Theoretical calculations reveal that ethane is activated on oxygen vacancies of the catalyst surface, favoring C-C coupling rather than C-H cleavage to produce n-butane.