Ni,Ni-Co和Co集群的表面氧性对甲激活的影响
Weifeng Tu1, Mireille Ghoussoub2, Chandra Veer Singh2,3
1Department of Chemical Engineering and Applied Chemistry, University of Toronto , Toronto, Ontario M5S 3E5, Canada.
Journal of the American Chemical Society
|April 18, 2017
概括
这项研究揭示了Ni-Co和Co集群上的甲和二氧化碳反应的新型C-H键激活路径,与Ni集群不同. 这种新途径增强了甲转化,并防止了Ni-Co双金属催化剂上的焦炭形成.
科学领域:
- 不同质的催化
- 表面化学
- 计算化学
背景情况:
- 甲 (CH4) 和二氧化碳 (CO2) 反应对于能量转化和碳利用至关重要.
- 了解最初的C-H键激活步骤是设计高效催化剂的关键.
- 之前对Ni集群的研究表明氧化添加,但对于其他金属可能存在新的途径.
研究的目的:
- 阐明氧友性Ni-Co和Co集群中CH4-CO2反应中的C-H键激活机制.
- 将Ni-Co和Co集群的反应路径与Ni集群的反应路径进行比较.
- 确定影响催化活性和焦炭形成的因素.
主要方法:
- 用密度函数理论 (DFT) 的计算来建模反应路径.
- 对C-H键裂变的过渡状态和能量障碍的分析.
- 研究氧原子和金属氧位点的作用.
主要成果:
- 在Ni-Co和Co集群上通过σ键转化确定了一种新的C-H键激活路径,涉及金属-氧位点对.
- Ni-Co 集群具有较高的氧友性,并形成有效的金属-氧裂变点.
- Co 集群也使用 σ 键转化,但由于较强的氧结合效果较差.
- CO2/CO比率决定了氧的化学潜力,并影响了速度决定的步骤.
- Ni-Co双金属集群显示出增强的CH4循环和完全抑制焦炭沉积.
结论:
- 氧性Ni-Co和Co集群在CH4-CO2反应中使用不同的σ键转化途径来激活C-H.
- 氧原子的存在和金属氧位点的形成对这种途径至关重要.
- 在没有焦炭形成的情况下,Ni-Co双金属集群为甲转化提供了卓越的催化性能.
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