CoNi Nanoparticles Supported on Hierarchical SAPO-34 Zeolite as a Catalyst for the Hydrolytic Dehydrogenation of Ammonia Borane
Wenwen Cong, Hongxia Zhang, Liancheng Bing, Fang Wang, Dezhi Han, Guangjian Wang
Abstract
Highly dispersed CoNi bimetallic nanoparticles (NPs) supported on hierarchical SAPO-34 zeolite were fabricated via impregnation followed by a hydrogen reduction method for ammonia borane (NH 3 BH 3, AB) hydrolysis to generate hydrogen. In order to investigate the effects of the Co/Ni weight ratio and zeolite synthesis procedure on the catalytic activity, Co x Ni y /SAPO-34 catalysts with various Co and Ni contents and zeolite particle sizes were prepared. It was found that Co 3.33 Ni 1.67 /SAPO-34-N containing 3.33:1.67 of the Co/Ni weight ratio and using nanosized hierarchical SAPO-34-N as support exhibited the highest catalytic activity among the investigated catalysts for the AB hydrolysis reaction, with a high turnover frequency (TOF) value of 9.25 mol H 2 (mol metal ·min) −1 at 30 °C, probably due to the promoted effect of nanosized hierarchical structure of SAPO-34 support on the dispersion and stabilization of CoNi particles as well as the synergistic catalysis of CoNi alloy NPs and Brønsted acid sites. Moreover, the Co 3.33 Ni 1.67 /SAPO-34-N catalyst also displayed excellent durability, with 83% of the catalytic activity of its initial state being preserved even after five cycles.