Systematic Study on Nitrogen Dissociation and Ammonia Synthesis by Lithium and Group 14 Element Alloys
Systematic Study on Nitrogen Dissociation and Ammonia Synthesis by Lithium and Group 14 Element Alloys
复制标题
DOI：
10.1021/acsaem.2c00213
复制
发表时间：
2022-03
影响因子：
6.4
通讯作者：
K. Shinzato;K. Tagawa;Koki Tsunematsu;Hiroyuki Gi;P. Singh;T. Ichikawa;H. Miyaoka
中科院分区：
文献类型：
--
作者：
K. Shinzato;K. Tagawa;Koki Tsunematsu;Hiroyuki Gi;P. Singh;T. Ichikawa;H. Miyaoka
研究了14族锂基合金在常温条件下合成氨（NH3）的准催化性能。在500℃以下，Li合金与氮（N2）反应生成氮化锂（Li3N）。氮化峰温度依次为Li4.4Si < Li4.4Ge≈Li4.4Pb < Li4.4Sn。n2解离活性与7Li固态魔角自旋核磁共振（7Li MAS NMR）光谱中观察到的Knight位移值有关，表明Li的金属特征是低温n2解离的重要因素。虽然合成nh3的反应产率取决于合金，但nh3是在240°C左右的相同温度下生成的，因为nh3的生成是由Li3N和氢（H2）之间的相同反应进行的，产生副产物氢化锂（LiH）。对于所有合金，LiH在较低温度下解吸h2形成Li合金，其Li成分高于纯LiH的热分解。此外，还对h2n2混合气体下的常规催化过程进行了研究。以Li4.4Si和Li4.4Ge为原料，在150℃和200℃下合成了nh3。
The pseudo-catalytic properties of lithium (Li)-based alloys with group 14 elements were investigated for ammonia (NH3) synthesis under ambient conditions. The reaction between the Li alloys and nitrogen (N2) proceeds below 500 °C to form lithium nitride (Li3N). The peak temperature of nitridation was lower in the order of Li4.4Si < Li4.4Ge ≈ Li4.4Pb < Li4.4Sn. The N2dissociation activity is related to the value of Knight shift observed in the7Li solid-state magic angle spinning nuclear magnetic resonance (7Li MAS NMR) spectra, indicating that the metallic feature of Li species is an important factor for low-temperature N2dissociation. Although the reaction yields for NH3synthesis were depending on the alloys, NH3was generated at the same temperature around 240 °C because the NH3formation proceeded by the same reaction between Li3N and hydrogen (H2), generating lithium hydride (LiH) as a by-product. For all the alloys, LiH desorbs H2to form Li alloys with higher Li composition at lower temperature than that of thermal decomposition of pure LiH. In addition, the conventional catalytic process was also investigated under a mixed gas of H2and N2. NH3was synthesized at 150 and 200 °C by using Li4.4Si and Li4.4Ge, respectively.