Ye Dongpei, Leung Kwan Chee, Niu Wentian, Duan Mengqi, Li Jiasi, Ho Ping-Luen, Szalay Dorottya, Wu Tai-Sing, Soo Yun-Liang, Wu Simson, Tsang Shik Chi Edman
Wolfson Catalysis Centre, Department of Chemistry, University of Oxford, Oxford OX1 3QR, UK.
National Synchrotron Radiation Research Centre, Hsinchu 30076, Taiwan.
iScience. 2024 Jul 22;27(8):110571. doi: 10.1016/j.isci.2024.110571. eCollection 2024 Aug 16.
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 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 h. It also gives an impressive hydrogen production rate of 31.3 mmol/(min g) with low apparent activation energy of 43 kJ mol. Fundamental studies indicate that the distinct average Ru-N 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 hence lowering the activation barrier for the decomposition over this catalyst.
氮掺杂碳材料已被研究用作氨分解的催化剂载体。在非晶态载体上已鉴定出4种不同类型的氮环境（石墨型、吡咯型、吡啶型和氮氧化物型）。在本文中，我们报道了一种在经预处理的氮掺杂碳上负载5%钌的催化剂，其边缘含氮位点含量高，在500°C和WHSV = 30,000 mL g⁻¹ h⁻¹时氨转化率超过90%。它还具有令人印象深刻的产氢速率，为31.3 mmol/(min g)，表观活化能低至43 kJ mol⁻¹。基础研究表明，边缘区域独特的平均Ru-N配位位点是这种高催化活性的原因。氨通过Ru-N(H)-N(H)-Ru中间体逐步分解。这种缔合机制避免了从金属表面直接裂解高能表面氮以形成N，从而降低了该催化剂分解反应的活化能垒。
