当前位置：
X-MOL 学术
›
ACS Catal.
›
论文详情
Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Distinguishing Active Site Identity in Sn-Beta Zeolites Using 31P MAS NMR of Adsorbed Trimethylphosphine Oxide
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-02-28 00:00:00 , DOI: 10.1021/acscatal.7b03533 Jennifer D. Lewis 1 , Michelle Ha 2 , Helen Luo 1 , Alexandra Faucher 2 , Vladimir K. Michaelis 2 , Yuriy Román-Leshkov 1
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-02-28 00:00:00 , DOI: 10.1021/acscatal.7b03533 Jennifer D. Lewis 1 , Michelle Ha 2 , Helen Luo 1 , Alexandra Faucher 2 , Vladimir K. Michaelis 2 , Yuriy Román-Leshkov 1
Affiliation
|
The identity of the active sites of hydrophobic Lewis acid zeolites was elucidated by solid-state 31P nuclear magnetic resonance (NMR) spectroscopy following adsorption of trimethylphosphine oxide (TMPO) probe molecules. The adsorption of TMPO on these materials resulted in distinct 31P NMR resonances between δiso = 59.9 and 54.9 ppm that correspond to unique chemical environments of the Lewis acidic heteroatoms in the Beta zeolite framework. The 31P NMR resonances were assigned to sites in Sn-Beta zeolites by correlating the variation of 31P NMR spectra during TMPO titration experiments with the corresponding changes in the 119Sn NMR spectra. This method allowed us to establish quantitative relationships between the assignments for each site and the catalytic activity for the glucose isomerization and aldol condensation reactions. The rate of glucose isomerization directly correlated with the combined integrated intensities of 31P MAS NMR resonances at δiso = 55.8 and 54.9 ppm, which amounted to 12–33% of total Sn sites. In contrast, the integrated peak area of a different site at δiso = 58.6 ppm was shown to correlate with aldol condensation activity. The probing method used to identify and quantify distinct active sites within the framework of low-defect Lewis acid zeolites developed in this work is applicable to a wide range of microporous materials, regardless of heteroatom identity.
中文翻译：
使用吸附的三甲基膦氧化物的31 P MAS NMR区分Sn-Beta沸石中的活性位点身份
在吸附三甲基氧化膦（TMPO）探针分子后，通过固态31 P核磁共振（NMR）光谱阐明了疏水路易斯酸沸石的活性位点的身份。TMPO对这些材料中的吸附导致明显31个δ之间P NMR共振异= 59.9和54.9 ppm的对应于在Beta沸石骨架的路易斯酸性杂独特化学环境。通过将TMPO滴定实验中31 P NMR光谱的变化与119中相应的变化相关联，将31 P NMR共振分配给Sn-Beta沸石中的位点Sn NMR谱。这种方法使我们能够在每个位点的赋值与葡萄糖异构化和醛醇缩合反应的催化活性之间建立定量关系。葡萄糖的异构化速率与δiso = 55.8和54.9 ppm时31 P MAS NMR共振的综合积分强度直接相关，占总Sn位点的12–33％。相反，在δiso处不同位点的积分峰面积显示出＝ 58.6ppm与醛醇缩合活性相关。在这项工作中开发的用于鉴定和定量低缺陷路易斯酸沸石框架内不同活性位点的探测方法，适用于各种微孔材料，而与杂原子身份无关。
更新日期：2018-02-28
中文翻译：
使用吸附的三甲基膦氧化物的31 P MAS NMR区分Sn-Beta沸石中的活性位点身份
在吸附三甲基氧化膦（TMPO）探针分子后，通过固态31 P核磁共振（NMR）光谱阐明了疏水路易斯酸沸石的活性位点的身份。TMPO对这些材料中的吸附导致明显31个δ之间P NMR共振异= 59.9和54.9 ppm的对应于在Beta沸石骨架的路易斯酸性杂独特化学环境。通过将TMPO滴定实验中31 P NMR光谱的变化与119中相应的变化相关联，将31 P NMR共振分配给Sn-Beta沸石中的位点Sn NMR谱。这种方法使我们能够在每个位点的赋值与葡萄糖异构化和醛醇缩合反应的催化活性之间建立定量关系。葡萄糖的异构化速率与δiso = 55.8和54.9 ppm时31 P MAS NMR共振的综合积分强度直接相关，占总Sn位点的12–33％。相反，在δiso处不同位点的积分峰面积显示出＝ 58.6ppm与醛醇缩合活性相关。在这项工作中开发的用于鉴定和定量低缺陷路易斯酸沸石框架内不同活性位点的探测方法，适用于各种微孔材料，而与杂原子身份无关。
京公网安备 11010802027423号