三亚乙基二胺在Al₂O₃上的吸附-II：与Al-OH基团的氢键作用

The adsorption of triethylenediamine on Al(2)O(3)-II: hydrogen bonding to Al-OH groups.

作者信息

Kim Sunhee, Byl Oleg, Yates John T

机构信息

Department of Chemistry, Surface Science Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15260.

出版信息

J Phys Chem B. 2005 Mar 3;109(8):3507-11. doi: 10.1021/jp040550+.

DOI:10.1021/jp040550+

PMID:16851386

Abstract

The hydrogen bonding of the triethylenediamine (TEDA) molecule to isolated Al-OH groups on partially dehydroxylated high area gamma-Al(2)O(3) powder has been studied using transmission IR spectroscopy. It has been found that TEDA adsorbs both singly and as multiple species to single Al-OH groups in clearly separable equilibrium stages of adsorption at 300 K. The reversible adsorption of a single TEDA molecule to Al-OH fits the Langmuir adsorption isotherm well, and the enthalpy of adsorption is found to be -15.6 +/- 0.5 kJ mol(-1) in the range of fractional coverage of 0.5-0.6. Red shifts of the Al-OH frequency from approximately -200 cm(-1) to approximately -1000 cm(-1) are observed as a result of -OH bonding to the N lone pair in the TEDA molecule.

摘要

利用透射红外光谱研究了三乙烯二胺（TEDA）分子与部分脱羟基的高比表面积γ-Al₂O₃粉末上孤立的Al-OH基团之间的氢键作用。研究发现，在300K下，TEDA在明显可分离的吸附平衡阶段，以单分子和多分子形式吸附到单个Al-OH基团上。单个TEDA分子对Al-OH的可逆吸附很好地符合朗缪尔吸附等温线，在分数覆盖范围为0.5 - 0.6时，吸附焓为-15.6±0.5kJ mol⁻¹。由于-OH与TEDA分子中的N孤对电子键合，观察到Al-OH频率从约-200cm⁻¹红移至约-1000cm⁻¹。