The Role of Lewis Acid Sites in γ‐Al 2 O 3 Oligomerization
The Role of Lewis Acid Sites in γ‐Al 2 O 3 Oligomerization
复制标题
路易斯酸位点在 γAl 2 O 3 齐聚中的作用
DOI：
10.1002/cphc.202300244
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发表时间：
2023
期刊：
影响因子：
2.9
通讯作者：
Miller, Jeffrey T.
中科院分区：
文献类型：
--
作者：
Breckner, Christian J.;Pham, Hien N.;Dempsey, Michael G.;Perez‐Ahuatl, Michelle A.;Kohl, Alyssa C.;Lytle, Corryn N.;Datye, Abhaya K.;Miller, Jeffrey T.
最近报道了γ-Al_2O_3催化烯烃齐聚反应，认为路易斯酸中心具有催化作用。这项研究的目的是确定每克氧化铝的活性中心的数量，以确认Lewis酸中心确实是催化的。添加无机氧化锶碱后，丙烯齐聚转化率在负载量为0.3 wt %时呈线性下降，而当负载量大于1 wt %时，转化率下降95 %。此外，随着锶负载量的增加，红外光谱中吸附的吡啶的Lewis酸峰强度线性下降，这与丙烯转化率的损失有关，这表明Lewis酸位是催化的。X射线光电子能谱和扫描电子显微镜表征表明，单一的锶离子结合在γ-Al_2O_3表面，每个锶离子毒化一个催化中心。假设均匀的表面覆盖率，毒化所有催化剂中心所需的最大负载量为∼0.4ngwt %sr，给出的酸中心密度为每nm2∼0.2nm2 中心，或大约3 nm2的氧化铝表面的γ 。
Olefin oligomerization by γ‐Al2O3has recently been reported, and it was suggested that Lewis acid sites are catalytic. The goal of this study is to determine the number of active sites per gram of alumina to confirm that Lewis acid sites are indeed catalytic. Addition of an inorganic Sr oxide base resulted in a linear decrease in the propylene oligomerization conversion at loadings up to 0.3 wt %; while, there is a >95 % loss in conversion above 1 wt % Sr. Additionally, there was a linear decrease in the intensity of the Lewis acid peaks of absorbed pyridine in the IR spectra with an increase in Sr loading, which correlates with the loss in propylene conversion, suggesting that Lewis acid sites are catalytic. Characterization of the Sr structure by XAS and STEM indicates that single Sr2+ions are bound to the γ‐Al2O3surface and poison one catalytic site per Sr ion. The maximum loading needed to poison all catalytic sites, assuming uniform surface coverage, was ∼0.4 wt % Sr, giving an acid site density of ∼0.2 sites per nm2of γ‐Al2O3, or approximately 3 % of the alumina surface.