TY - JOUR

T1 - Interaction of metallic magnesium with ammonia

T2 - Mechanochemical synthesis of Mg(NH2)2 for hydrogen storage

AU - Hu, Mengru

AU - Sun, Xin

AU - Li, Bo

AU - Li, Peng

AU - Xiong, Meichai

AU - Tan, Jun

AU - Ye, Zhangze

AU - Eckert, Jürgen

AU - Liang, Chu

AU - Pan, Hongge

N1 - Publisher Copyright: © 2022 Elsevier B.V.

PY - 2022/6/25

Y1 - 2022/6/25

N2 - Mg(NH2)2-2LiH is one of the most promising hydrogen storage systems to be applied in hydrogen powered vehicles as hydrogen source. However, the synthesis of the main raw material Mg(NH2)2 is high-cost and time-consuming for the present technologies. Herein, we report a low-cost, time-saving and low-carbon method to synthesize Mg(NH2)2 by mechanochemical reaction of metallic Mg with ammonia. After 72 h of mechanochemical reaction, amorphous Mg(NH2)2 is successfully synthesized by milling metallic Mg and ammonia at room temperature. A two-stage reaction is demonstrated to be responsible for the conversion of Mg and ammonia into Mg(NH2)2. In the initial process of ball milling, Mg particles tend to clump and agglomerate because of the ductility of metallic Mg. The first reaction stage between metallic Mg and ammonia occurs at the surfaces and interfaces of bulk Mg to form MgH2 and Mg(NH2)2 powders. With prolonged milling time, the size of bulk Mg decreases with milling time due to the continuous occurrence of the first-stage reaction. The second-stage reaction is confirmed to be the reaction of MgH2, developed in the first reaction stage, with ammonia to produce Mg(NH2)2. The as-synthesized Mg(NH2)2 is used as raw material for synthesizing Mg(NH2)2-2LiH material, showing almost the same hydrogen storage performance as the Mg(NH2)2 synthesized by heating Mg and ammonia. This study provides a new method to synthesize Mg(NH2)2 for hydrogen storage on a large scale.

AB - Mg(NH2)2-2LiH is one of the most promising hydrogen storage systems to be applied in hydrogen powered vehicles as hydrogen source. However, the synthesis of the main raw material Mg(NH2)2 is high-cost and time-consuming for the present technologies. Herein, we report a low-cost, time-saving and low-carbon method to synthesize Mg(NH2)2 by mechanochemical reaction of metallic Mg with ammonia. After 72 h of mechanochemical reaction, amorphous Mg(NH2)2 is successfully synthesized by milling metallic Mg and ammonia at room temperature. A two-stage reaction is demonstrated to be responsible for the conversion of Mg and ammonia into Mg(NH2)2. In the initial process of ball milling, Mg particles tend to clump and agglomerate because of the ductility of metallic Mg. The first reaction stage between metallic Mg and ammonia occurs at the surfaces and interfaces of bulk Mg to form MgH2 and Mg(NH2)2 powders. With prolonged milling time, the size of bulk Mg decreases with milling time due to the continuous occurrence of the first-stage reaction. The second-stage reaction is confirmed to be the reaction of MgH2, developed in the first reaction stage, with ammonia to produce Mg(NH2)2. The as-synthesized Mg(NH2)2 is used as raw material for synthesizing Mg(NH2)2-2LiH material, showing almost the same hydrogen storage performance as the Mg(NH2)2 synthesized by heating Mg and ammonia. This study provides a new method to synthesize Mg(NH2)2 for hydrogen storage on a large scale.

KW - Ammonia

KW - Hydrogen storage

KW - Magnesium amide

KW - Mechanical milling

KW - Metallic magnesium

UR - http://www.scopus.com/inward/record.url?scp=85126089258&partnerID=8YFLogxK

U2 - 10.1016/j.jallcom.2022.164397

DO - 10.1016/j.jallcom.2022.164397

M3 - Article

AN - SCOPUS:85126089258

VL - 907.2022

JO - Journal of alloys and compounds

JF - Journal of alloys and compounds

SN - 0925-8388

IS - 25 June

M1 - 164397

ER -