Oliviero Laetitia, Vimont Alexandre, Lavalley Jean-Claude, Romero Sarria Francisca, Gaillard Marina, Maugé Françoise
Laboratoire Catalyse et Spectrochimie, UMR CNRS, ENSICAEN, University of Caen, 6 Bd du Maréchal Juin, 14050 Caen Cedex, France.
Phys Chem Chem Phys. 2005 Apr 21;7(8):1861-9. doi: 10.1039/b500689a.
The positions of nu8a and nu*(NH) bands in the spectrum of protonated 2,6-dimethylpyridine vary with the strength of Brønsted acidity: the higher the nu*(NH) wavenumber and the lower the nu8a wavenumber, the stronger the acidity. The results obtained with 2,6-dimethylpyridine adsorption correlate with those obtained by CO adsorption experiments on a series of faujasite zeolites (LiHNaY, KHNaY, HY, HY(SA), HNaX). These relations were extended to gamma-Al2O3 having weak Brønsted acidity, not detected by pyridine and hardly detected by CO. The number (0.1 per nm2) and the strength (corresponding to delta nu (OH) by CO = 155 cm(-1)) of the most acidic OH groups of Al2O3, as well as the position of the corresponding nu (OH) band (<3700 cm(-1)) are deduced from 2,6-dimethylpyridine adsorption experiments.
质子化2,6 - 二甲基吡啶光谱中ν8a和ν*(NH)谱带的位置随布朗斯特酸度强度而变化：ν*(NH)波数越高且ν8a波数越低，酸度越强。用2,6 - 二甲基吡啶吸附得到的结果与通过在一系列八面沸石（LiHNaY、KHNaY、HY、HY(SA)、HNaX）上进行CO吸附实验得到的结果相关。这些关系扩展到了具有弱布朗斯特酸度的γ - Al₂O₃，吡啶未检测到其酸度，CO也几乎检测不到。通过2,6 - 二甲基吡啶吸附实验推断出Al₂O₃最酸性OH基团的数量（每nm² 0.1个）和强度（对应于CO的δν(OH) = 155 cm⁻¹）以及相应ν(OH)谱带的位置（<3700 cm⁻¹）。
