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Hydrogen release mechanism and performance of ammonia borane catalyzed by transition metal catalysts Cu‐Co/MgO(100)
Author(s) -
Li Haojie,
Yan Yunfei,
Feng Shuai,
Chen Yanrong,
Li Lixian,
Zhang Li,
Yang Zhongqing
Publication year - 2019
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.4325
Subject(s) - dehydrogenation , ammonia borane , catalysis , chemistry , transition metal , density functional theory , hydrogen storage , inorganic chemistry , molecule , metal , hydrogen , transition state , computational chemistry , organic chemistry
Summary The catalytic dehydrogenation of ammonia borane (NH 3 BH 3 , AB) molecule is most frequently employed by metal catalysts, but a reliable dehydrogenation mechanism in molecular level has yet to be fully illuminated. Herein, adopting the density functional theory (DFT) method, the dehydrogenation mechanism and performance of NH 3 BH 3 under the transition metal catalysts (Cu/MgO, Co/MgO, CuCo/MgO) were studied. The calculated results show that the dehydrogenation mechanism of AB refers to stepwise dehydrogenation mechanism: AB is adsorbed in the transition metal catalysts firstly, then one H(N) atom transferred to H(B) of ―BH 3 and to form H 2 molecule via the broken of B―H and N―H bond, finally, H 2 molecule desorption from the catalyst complexes. Among the transition metal catalysts, CuCo/MgO have the perfect catalytic activity in dehydrogenation reaction of NH 3 BH 3 , its barrier energy of the feasible pathway (path A) is 22.26 kcal/mol, which is lower than the barrier energy of AB‐Cu/MgO(28.13 kcal/mol), AB‐Co/MgO(27.46 kcal/mol), and the results of thermogravimetric analysis further verified the reasonability of DFT calculational results. Besides, partial density of states calculational results show the electron orbital hybridization of Cu, Co atom may account for the excellent catalytic performance of CuCo/MgO(100) compared with the Cu/MgO(100) and Co/MgO(100) in dehydrogenation process of AB.