Building of the absolute scale for the acidity of zeolites using probe molecules

沸石的酸性中心在沸石的催化过程中起着重要的作用。因此，利用各种技术对沸石的酸性进行了广泛的研究。然而，使用不同的技术或不同的探针分子获得的结果之间往往存在一些差异。因此，我们对传统上使用的吡啶或氨、作者最近提出的二氮素和近年来广泛使用的一氧化碳作为红外光谱探针分子的结果进行了比较研究，并进一步考察了水分子作为酸性中心的红外光谱探针分子的性质。结果表明，水分子优先吸附在Lewis酸性中心上，然后再吸附在Brensted酸性中心上。因此，水分子可用于半定量测定Lewis酸性中心。研究了不同分子长度的烷烃在铁铁矿小孔沸石上的吸附。这种方法使我们能够根据沸石孔到孔的距离来研究孔附近酸性中心的性质。因此，我们已经发现，我们可以利用不同分子长度的化学相似的分子来研究孔洞附近的酸性中心的位置。

Acidic sites of zeolites play an important role in the catalytic processes over the zeolites. Hence, the acidic properties of zeolites have been extensively studied using various techniques. However, it is often the case that there are some discrepancies among the results obtained using different techniques or different probe molecules. So, we have carried out a comparative study on the results obtained using pyridine or ammonia that have been traditionally used, dinitrogen that has been recently proposed by the authors, and carbon monoxide that has been widely used in recent years, as infrared spectroscopic probe molecules.Further, we have investigated the properties of water molecules as an infrared spectroscopic probe molecule of acidic sites. It was shown that water molecules adsorbs preferentially on Lewis acidic sites and then on Brensted acidic sites. Thus water molecules can be used to semi-quantitative measurement of Lewis acidic sites.The adsorptions of various alkanes with different molecular length on ferierite zeolites, which is the zeolites with small pores, have been studied. This method makes us possible to study the properties of acidic sites near the aperture of the zeolites pores according to their distance from the aperture. Thus it has been found that we can investigate the position of the acidic sites near the pore aperture using chemically similar molecules with different molecular length.