Active nitrogen sites on nitrogen doped carbon for highly efficient associative ammonia decomposition

作者：Dongpei Ye, Kwan Chee Leung, Wentian Niu, Mengqi Duan, Jiasi Li, Ping-Luen Ho, Dorottya Szalay, Tai‐Sing Wu, Y. L. Soo, Simson Wu, Shik Chi Edman Tsang · 发表于：iScience · 年份：2024 · DOI：10.1016/j.isci.2024.110571 · 被引用次数：20 · 研究领域：Ammonia Synthesis and Nitrogen Reduction、Catalytic Processes in Materials Science、Hydrogen Storage and Materials

Nitrogen doped carbon materials have been studied as catalyst support for ammonia decomposition. There are 4 different types of nitrogen environments (graphitic, pyrrolic, pyridinic and nitrogen oxide) on the amorphous support identified. In this paper, we report a 5%Ru on MgCO 3 pre-treated nitrogen doped carbon catalyst with high content of edge nitrogen-containing sites which displays an ammonia conversion rate of over 90% at 500°C and WHSV = 30,000 mL g cat −1 h −1 . It also gives an impressive hydrogen production rate of 31.3 mmol/(min g cat ) with low apparent activation energy of 43 kJ mol −1 . Fundamental studies indicate that the distinct average Ru-N 4 coordination site on edge regions is responsible for such high catalytic activity. Ammonia is stepwise decomposed via a Ru-N(H)-N(H)-Ru intermediate. This associative mechanism circumvents the direct cleavage of energetic surface nitrogen from metal to form N 2 hence lowering the activation barrier for the decomposition over this catalyst.