Estimation of hydrogen bond distribution in coal through the analysis bf OH stretching bands in diffuse reflectance infrared spectrum-measured by in-situ technique
Estimation of hydrogen bond distribution in coal through the analysis bf OH stretching bands in diffuse reflectance infrared spectrum-measured by in-situ technique
复制标题
DOI：
10.1021/ef0001787
复制
发表时间：
2001-05-01
期刊：
影响因子：
5.3
通讯作者：
Kumano, A
中科院分区：
文献类型：
--
作者：
Miura, K;Mae, K;Kumano, A
提出了一种估算煤中氢键强度分布的新方法。氢键包括煤分子内氢键和煤中羟基形成的煤-水氢键。该方法分析的FTIR光谱范围从2400至3700 cm（-1）使用原位漫反射红外傅立叶变换（DRIFT）技术与纯，未稀释，煤样。在八种煤（七种阿贡优质煤和一种澳大利亚褐煤）、一种离子交换树脂和一种木质素的加热过程中，从室温到300 ℃每隔20 ℃测量一次FTIR光谱。每个光谱被分为6个氢键的吸收带的曲线分辨方法，然后的量的羟基有助于每个氢键的比尔定律估计通过使用不同的吸收率为每个波段。每个氢键的强度使用Drago等人提出的关系来估计，该关系被称为“线性光谱-光谱位移关系”之一。用这种分析方法，成功地估计了所有样品的氢键分布（HBD）随温度的变化。利用HBD，很好地估计了与吸附水的脱附、玻璃化转变和COOH基团的分解有关的氢键的变化。只有FTIR光谱测量被发现是足够的，以获得这样的光谱。这大大简化了计算过程，提高了计算精度。很好地阐明了所提出的原位FTIR测量方法和用于获得HBD的分析方法的有效性。
A new method was presented to estimate the strength distribution of hydrogen bonds in coal. The hydrogen bonds include the coal intramolecule hydrogen bonds and coal-water hydrogen bonds formed by hydroxyls in coal. The method analyzes the FTIR spectrum ranging from 2400 to 3700 cm(-1) obtained using the in-situ diffuse reflectance IR Fourier transform (DRIFT) technique with neat, undiluted, coal samples. The FTIR spectra during the heat-up of eight coals (seven Argonne premium coals and an Australian brown coal); an ion-exchange resin, and a lignin were measured every 20 degreesC from room temperature to 300 degreesC. Each spectrum was divided into six hydrogen-bonded absorption bands by a curve-resolving method, then the amount of hydroxyls contributing to each hydrogen bond was estimated by Beer's law by using different absorptivity for each band. The strength of each hydrogen bond was estimated using a relation presented by Drago et al, that is known as one of the "linear enthalpy-spectroscopic shift relations". Using this analysis method, changes in hydrogen bond distributions (HBD) with increasing temperature were successfully estimated for all the samples examined, By utilizing the HBD the changes in enthalpies associated with the desorption of adsorbed water, the glass transition, and the decomposition of COOH groups were well:estimated. Only FTIR spectra measurements were found to be enough to obtain such enthalpies. This greatly simplified the calculation procedure and increased the accuracy of the enthalpies. The validity: of the proposed in situ FTIR measurement method and the analysis method for obtaining HBD was well clarified.