Alkali and Alkaline Earth Hydrides-Driven N-2 Activation and Transformation over Mn Nitride Catalyst

Release time:2020-05-23

Impact Factor:14.695

DOI number:10.1021/jacs.8b08334

Affiliation of Author(s):Chinese Acad Sci, Dalian Inst Chem Phys

Journal:J. Am. Chem. Soc.

Abstract:Early 3d transition metals are not focal catalytic candidates for many chemical processes because they have strong affinities to O, N, C, or H, etc., which would hinder the conversion of those species to products. Metallic Mn, as a representative, undergoes nitridation under ammonia synthesis conditions forming bulk phase nitride and unfortunately exhibits negligible catalytic activity. Here we show that alkali or alkaline earth metal hydrides (i.e., LiH, NaH, KH, CaH2, and BaH2, AHs for short) promotes the catalytic activity of Mn nitride by orders of magnitude. The sequence of promotion is BaH2 > LiH > KH > CaH2 > NaH, which is different from the order observed in conventional oxide or hydroxide promoters. AHs, featured by bearing negatively charged hydrogen atoms, have chemical potentials in removing N from Mn nitride and thus lead to significant enhancement of N-2 activation and subsequent conversion to NH3. Detailed investigations on Mn-LiH catalytic system disclosed that the active phase and kinetic behavior depend strongly on reaction conditions. Based on the understanding of the synergy between AHs and Mn nitride, a strategy in the design and development of early transition metals as effective catalysts for ammonia synthesis and other chemical processes is proposed.

Co-author:Xingguo, Li, Jie, Zheng, Guotao, Wu, Wenbo, Gao, Peikun, Wang, Xinghua, Chang, Yeqin, Guan

First Author:Fei, Chang

Indexed by:Journal paper

Correspondence Author:Jianping, Guo

First-Level Discipline:0805 材料科学与工程

Document Type:J

Translation or Not:no

Date of Publication:2018-11-01