Petroleum is the essential feedstock for modern society, which could be cracked or fractionated to produce alkenes, long-chain alkanes, aromatics, these molecules were then converted to important chemicals or valuable products. As petroleum is non-renewable resource, methane was beginning to be applied as an alternative resource for petroleum. What’s more, methane could be formed easily by microbe degradation of numerous carbon-containing wastes, therefore using methane could help reach "carbon balance earth". Layered double hydroxide (LDH) compounds exhibit as 2D layered structure which is composed with adjustable multi-metals and balancing anions, therefore the catalytic performance could be significantly alternated by modulating electronic structure of the catalytic sites as well as metal species. Vacancy was important catalytic site, and exhibited as highly active O-centered radical that activate methane C-H bond by H atom abstraction (HAT) during photocatalysis. Contrary to O2 which form various O-containing radicals including OH., O2●-, O vacancy would form distinct O., therefore help achieve better photocatalysis selectivity. A series of binary LDH materials were fabricated, which are Ti containing LDH (Zn-Ti, Ni-Ti, Cu-Ti-LDH) and Zn containing LDH (Zn-Al, Zn-Cr, Zn-Ga-LDH). We found that in these binary LDH compounds, Zn-Ti-LDH displayed the best methane conversion performance. We attributed the high catalytic performance to the vacancy of the Zn-Ti binary site. Most previous reports yield C2H6 during methane nonoxidative reaction, however, Zn-Ti LDH photocatalyst could produce C2H4 as well as C2H6, which was caused by the strong catalytic dehydrogenation ability of vacancy site, and the overall reaction was composed by nonoxidative methane coupling and ethane dehydrogenation. The methane conversion rate under UV light irradiation was around 113.7 μmol g-1 h-1, with half ethylene selectivity. This finding would help develop photocatalyst with adjustable product selectivity by construct high efficient cascade catalyst system.

Photo-induced methane nonoxidative conversion on Ti-containing layered double hydroxide nanocomposite

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.