加化:一种高选择性的无氧化脱催化剂
Yong Yuan1, Jason S Lee1, Raul F Lobo1
1Center for Catalytic Science and Technology, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States.
化热质有效催化脱,在热质孔中形成活跃的 Ga+ 位点. 通过多环芳去活化是可逆的,强调Ga+是这种反应的关键活性中心.
科学领域:
- 催化剂
- 材料科学
- 化学工程
背景情况:
- 脱 (PDH) 对于生产石油化学原料烯至关重要.
- 焦化物是广泛使用的催化剂,但了解活性位点和失活机制对于优化至关重要.
- 沙巴 (Ga-CHA) 焦化物对PDH具有前景,但需要详细描述活性部位和稳定性.
研究的目的:
- 为了阐明Ga-CHA热中负责脱的活性位点.
- 研究Ga-CHA催化剂的失活机制和再生途径.
- 将 Ga+ 位点的催化性能与 CHA 焦化物中的其他金属子进行比较.
主要方法:
- 在现场里埃变换红外光谱和脉冲定位以识别活性位点.
- 支持实验发现的密度函数理论 (DFT) 计算.
- 紫外线光谱,用于监测停用过程中碳酸性物种的形成.
- 在各种条件下对脱的催化试验.
主要成果:
- 表面的 Ga2O3 减少并扩散到焦岩孔中,形成活跃的外框架 Ga+ 位点.
- Ga+位点可逆地与H2反应形成GaH,形成的计算度为~-51.2 kJ·mol-1.
- 由于多环芳的形成,脱率最初迅速下降,导致失活.
- 催化剂可以在600°C时通过氧化碳沉积物完全再生.
- 外框架Ga+站点被证实是活跃的中心,其活动明显高于In+站点.
结论:
- 在Ga-CHA石中的外框架Ga+位点是脱的主要活性中心.
- 主要因可逆焦炭形成而失活,可通过氧化去除.
- Ga-CHA焦化物提供了一个稳定和可再生的催化系统,用于高效的烯生产.
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