Bronsted acidity of extraframework debris in steamed Y zeolites from the FTIR study of CO adsorption
Bronsted acidity of extraframework debris in steamed Y zeolites from the FTIR study of CO adsorption
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DOI：
10.1039/a803886d
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发表时间：
1998-10-07
期刊：
影响因子：
--
通讯作者：
Lavalley, JC
中科院分区：
文献类型：
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作者：
Cairon, O;Chevreau, T;Lavalley, JC
采用红外光谱法研究了低温条件下酸浸蒸Y沸石和两种硅铝比不同的硅铝样品对CO的递进吸附。Y型沸石的红外光谱在v（OH）范围内较为复杂。CO吸附后，先前只分配了一些扰动的v（OH）和v（CO）带。这项研究表明，在蒸Y沸石中观察到的一些特定的Bronsted酸位点也存在于二氧化硅-氧化铝样品中，使我们能够将它们与二氧化硅-氧化铝碎屑联系起来。在硅铝样品中，更强的酸性位点强度[表现为在3450 cm（-1）附近的扰动v（OH）带]与未脱铝HY沸石的高频（HF）OH基团接近。通过测定相应扰动v（CO）波段的摩尔吸收系数epsilon(CO)，可以对这些位置进行定量估计。
Progressive CO adsorption has been studied by IR spectroscopy, at low temperature on acid-leached steamed Y zeolites and on two silica-alumina samples with different Si/Al ratios. The IR spectra of the steamed Y zeolites are complex in the v(OH) range. After CO adsorption only some perturbed v(OH) and v(CO) bands had previously been assigned. This study showed that some specific Bronsted acid sites observed in steamed Y zeolites were also present in silica-alumina samples, allowing us to relate them to silica-alumina debris. On the silica-alumina samples, the more acidic site strength [characterized by a perturbed v(OH) band near 3450 cm(-1)] was found to be close to that of the high-frequency (HF)OH groups of non-dealuminated HY zeolites. A quantitative estimation of such sites was obtained by determination of the molar absorption coefficient epsilon(CO) of the corresponding perturbed v(CO) band.