Prediction of Crude Oil Properties and Chemical Composition by Means of Steady-State and Time-Resolved Fluorescence
Prediction of Crude Oil Properties and Chemical Composition by Means of Steady-State and Time-Resolved Fluorescence
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DOI：
10.1021/ef200567x
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发表时间：
2011-08-01
期刊：
影响因子：
5.3
通讯作者：
Nascimento, Claudio A. O.
中科院分区：
文献类型：
--
作者：
Pantoja, Patricia A.;Lopez-Gejo, Juan;Nascimento, Claudio A. O.
稳态和时间分辨荧光测量报告几种原油和它们的饱和物，芳烃，树脂，和沥青质（SARA）馏分（饱和物，芳烃和树脂），从沥青质戊烷沉淀后的maltene分离。原油的美国石油协会（API）等级与其荧光发射强度和最大值之间存在明显的关系。用环己烷稀释原油样品导致发射强度的显著增加和蓝移，这清楚地表明原油中存在的发射发色团之间存在能量转移过程。三种SARA馏分及其混合物的荧光光谱和平均荧光寿命表明，芳烃和胶质是原油排放的主要贡献者。总同步荧光扫描（TSFS）光谱图是最好的稳态荧光光谱之间的馏分进行区分，使TSFS地图的一个特别有趣的选择，为基础的荧光方法的表征和原油分类的发展。更详细的研究，使用范围更广的激发和发射波长，是必要的，以确定时间分辨荧光（TRF）数据的效用为此目的。利用21个原油样品的TSFS光谱建立的初步模型显示，API的计算值和测量值与SARA馏分浓度之间具有很好的相关性（R-2 > 0.88）。因此，使用基于快速荧光测量的模型可以替代炼油厂中繁琐且耗时的化学分析。
Steady-state and time-resolved fluorescence measurements are reported for several crude oils and their saturates, aromatics, resins, and asphaltenes (SARA) fractions (saturates, aromatics and resins), isolated from maltene after pentane precipitation of the asphaltenes. There is a clear relationship between the American Petroleum Institute (API) grade of the crude oils and their fluorescence emission intensity and maxima. Dilution of the crude oil samples with cyclohexane results in a significant increase of emission intensity and a blue shift, which is a clear indication of the presence of energy-transfer processes between the emissive chromophores present in the crude oil. Both the fluorescence spectra and the mean fluorescence lifetimes of the three SARA fractions and their mixtures indicate that the aromatics and resins are the major contributors to the emission of crude oils. Total synchronous fluorescence scan (TSFS) spectral maps are preferable to steady-state fluorescence spectra for discriminating between the fractions, making TSFS maps a particularly interesting choice for the development of fluorescence-based methods for the characterization and classification of crude oils. More detailed studies, using a much wider range of excitation and emission wavelengths, are necessary to determine the utility of time-resolved fluorescence (TRF) data for this purpose. Preliminary models constructed using TSFS spectra from 21 crude oil samples show a very good correlation (R-2 > 0.88) between the calculated and measured values of API and the SARA fraction concentrations. The use of models based on a fast fluorescence measurement may thus be an alternative to tedious and time-consuming chemical analysis in refineries.