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Hydrogen generation via ammonia decomposition on highly efficient and stable Ru-free catalysts: approaching complete conversion at 450 °C
Energy & Environmental Science ( IF 32.5 ) Pub Date : 2022-08-16 , DOI: 10.1039/d1ee03730g
Hassina Tabassum , Shreya Mukherjee , Junjie Chen , Domoina Holiharimanana , Stavros Karakalos , Xiaoxuan Yang , Sooyeon Hwang , Tianyu Zhang , Bo Lu , Min Chen , Tang Zhong , Eleni Kyriakidou , Qingfeng Ge , Gang Wu

Hydrogen (H2) is a prospective zero-carbon and high-energy-density fuel alternative to fossil fuels for generating power and clean energy. Ammonia (NH3) is a promising H2 (17.7%) carrier, which can easily overcome the challenges associated with H2 storage and transportation. Thermocatalytic ammonia decomposition reaction (ADR) is an effective way to produce clean H2 but it relies on the use of expensive and rare ruthenium (Ru)-based catalysts at elevated temperatures (>500 °C), hence is not sustainable and economically feasible. Herein, we report a synergistic strategy to design a heterostructured Ru-free catalyst, consisting of CoNi alloy nanoparticles well-dispersed on a MgO–CeO2–SrO mixed oxide support with potassium promotion. The resulting K–CoNialloy–MgO–CeO2–SrO catalyst presents 97.7% and 87.5% NH3 conversion efficiency at 450 °C at gas hourly space velocities (GHSVs) of 6000 and 12 000 mL h−1 gcat−1, respectively. At 500 °C, the H2 production rate (57.75 mmol gcat−1 min−1) becomes comparable to that of most of the reported Ru-based catalysts. The catalyst stability has been successfully demonstrated in both a fixed-bed reactor under high pressure (120 h at 5.0 bar) and a membrane reactor prototype (600 h at 1.5 bar) at 500 °C. High-temperature in situ XPS analysis, temperature-programmed desorption/reduction, and density functional theory calculations have been carried out to elucidate the possible active sites and performance enhancement mechanisms. This work highlights the importance of constructing optimal interfaces between active metal nanoparticles and oxide support for boosting the NH3 to H2 conversion efficiency and long-term stability.

中文翻译:

在高效稳定的无钌催化剂上通过氨分解制氢:在 450 °C 时接近完全转化

氢 (H 2 ) 是一种有前景的零碳和高能量密度燃料替代化石燃料,用于发电和清洁能源。氨(NH 3)是一种很有前途的H 2(17.7%)载体,可以轻松克服与H 2储存和运输相关的挑战。热催化氨分解反应 (ADR) 是生产清洁 H 2的有效方法,但它依赖于在高温 (>500 °C) 下使用昂贵且稀有的钌 (Ru) 基催化剂,因此不可持续且经济上不可行. 在此,我们报告了一种协同策略来设计一种异质结构的无钌催化剂,该催化剂由良好分散在 MgO-CeO 2上的 CoNi 合金纳米颗粒组成。-SrO 混合氧化物载体与钾促进。得到的 K-CoNi合金-MgO-CeO 2 -SrO 催化剂在 450 °C 和 6000 和 12 000 mL h -1 g cat -1的气时空速 (GHSV) 下分别表现出 97.7% 和 87.5% 的 NH 3转化效率,分别。在 500 °C 时,H 2产率(57.75 mmol g cat -1 min -1)变得与大多数报道的Ru基催化剂相当。催化剂稳定性已在高压下的固定床反应器(5.0 bar 下 120 小时)和 500 °C 下的膜反应器原型(1.5 bar 下 600 小时)中得到成功证明。高温原位已经进行了 XPS 分析、程序升温解吸/还原和密度泛函理论计算,以阐明可能的活性位点和性能增强机制。这项工作强调了在活性金属纳米颗粒和氧化物载体之间构建最佳界面对于提高 NH 3到 H 2的转化效率和长期稳定性的重要性。
更新日期:2022-08-16
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