Identification of the active site during CF4 hydrolytic decomposition over γ-Al2O3
Identification of the active site during CF4 hydrolytic decomposition over γ-Al2O3
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γ-Al2O3 上 CF4 水解过程中活性位点的识别
DOI：
10.1039/d1en01202a
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Liu Min
中科院分区：
文献类型：
--
作者：
Zhang Hang;Luo Tao;Long Yan;Chen Yingkang;Fu Junwei;Liu Hui;Hu Junhua;Lin Zhang;Chai Liyuan;Liu Min
铝生产过程会将四氟化碳（CF 4）直接排放到大气中，这是一种强大的温室气体（温室升温潜能值是CO2的6500倍），具有严重加剧全球变暖的潜力。作为消除CF 4的最可行的方法，由于活性位点仍然难以捉摸，在中等温度下CF 4的水解仍然具有挑战性。结果表明，在CF 4的水解过程中，γ-Al 2 O3（110）表面上的三配位Al（AlIII）是主要的活性中心。密度泛函理论计算表明，CF 4在AlIII位点上有较强的吸附作用。制备了不同Al Ⅲ占位水平的γ-Al 2 O3纳米片，其（110）晶面暴露。通过~（27）Al MAS NMR对催化剂中Al Ⅲ的含量进行了定量分析，Al Ⅲ的含量直接影响催化剂的活性。原位红外光谱表明，铝III网站可以被激活，他们有一个稳定的存在下，在给定的反应条件。
Aluminum production processes emit carbon tetrafluoride (CF4) directly into the atmosphere, which is a powerful greenhouse gas (with a greenhouse warming potential 6500 times that of CO2) with serious potential to exacerbate global warming. As the most feasible method of eliminating CF4, the hydrolytic decomposition of CF4 at moderate temperatures is still challenging due to the active site remaining elusive. Herein, we demonstrated that three-coordinated Al (AlIII) on the γ-Al2O3 (110) surface is the dominant active site during the hydrolytic decomposition of CF4. DFT calculations present the strong adsorption of CF4 on the AlIII site. γ-Al2O3 nano-slices with exposed (110) crystal planes with different AlIII occupation levels were synthesized. The amounts of AlIII in the catalysts were quantified via27Al MAS NMR and the number of AlIII sites directly affects the catalytic activity. In situ FTIR spectra show that the AlIII sites could be activated and that they had a stable presence under the given reaction conditions.