Catalytic ammonia synthesis on HY-zeolite-supported angstrom-size molybdenum cluster.

The development of new catalysts with high N activation ability is an effective approach for low-temperature ammonia synthesis. Herein, we report a novel angstrom-size molybdenum metal cluster catalyst for efficient ammonia synthesis. This catalyst is prepared by the impregnation of a molybdenum halide cluster complex with an octahedral Mo metal core on HY zeolite, followed by the removal of all the halide ligands by activation with hydrogen. In this activation, the size of the Mo cluster ( 7 Å) is almost retained. The resulting angstrom-size cluster shows catalytic activity for ammonia synthesis from N and H, and the reaction proceeds continuously even at 200 °C under 5.0 MPa. DFT calculations suggest that N[triple bond, length as m-dash]N bond cleavage is promoted by the cooperation of the multiple molybdenum sites.