Sulfur removal is one of the key functions of vacuum gas oil (VGO) hydrotreating reactors. Knowing feed and product properties real-time or near-real-time improves reactor operations. The VGO section of crude distillation unit is also prone to severe high-temperature sulfidic and naphthenic acid corrosion. In this article, we evaluate a single-reflectance attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy as a possible quick and cost-effective methodology to determine total carboxylic acid number (TCAN) and total sulfur content of VGO. The study shows that single-reflectance diamond ATR crystal methodology has the right signal-to-noise ratio to accurately predict TCAN and total sulfur within the primary method’s repeatability. Statistical models have been developed using 64 sample sets of vacuum gas oil and out of which 10 samples were used for the cross-validation of the model. The range of TCAN in VGO samples used in this study was between 0.37 and 13.8 mg KOH/g, and sulfur content was between 0.8 to 5.4% by mass. Models have been evaluated by determining the correlation coefficient (R²), linearity curves obtained by plotting measured versus predicted values, and the errors associated with the prediction and cross-validation. The models showed a correlation coefficient of 0.9991 for TCAN and 0.9974 for total sulfur between reference and the measured values for calibration set of samples. A root-mean-square error of calibration (RMSEC) and prediction (RMSEP) for TCAN were found to be 0.0903 and 0.0885 mg KOH/g. Similarly, RMSEC and RMSEP values for sulfur content were 0.0829 and 0.107% by mass, respectively. The proposed methodology for the prediction of total sulfur and TCAN is fast, efficient, and cost-effective and has several advantages over the standard methods.

中文翻译：

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衰减全反射傅里叶变换红外光谱法测定真空粗柴油中的硫和总羧酸数量

脱硫是真空瓦斯油（VGO）加氢处理反应器的关键功能之一。实时或接近实时地了解进料和产品特性可以改善反应器的运行。原油蒸馏装置的VGO部分也容易受到高温硫化物和环烷酸的严重腐蚀。在本文中，我们评估单反射衰减全反射傅里叶变换红外（ATR-FTIR）光谱技术，作为测定总羧酸值（TCAN）和VGO的总硫含量的一种可能的快速且经济高效的方法。研究表明，单反射金刚石ATR晶体方法具有正确的信噪比，可以在主要方法的可重复性范围内准确预测TCAN和总硫。使用64种真空瓦斯油样本集开发了统计模型，其中10个样本用于模型的交叉验证。本研究中使用的VGO样品中TCAN的范围为0.37至13.8 mg KOH / g，硫含量为0.8至5.4质量％。通过确定相关系数对模型进行了评估（R ²），通过绘制测得值与预测值的关系曲线得出的线性曲线，以及与预测和交叉验证相关的误差。该模型显示，TCAN的相关系数为0.9991，总硫含量为0.9974的相关系数与样品校准组的测量值之间的相关系数。TCAN的校准均方根误差（RMSEC）和预测均方根误差（RMSEP）为0.0903和0.0885 mg KOH / g。同样，硫含量的RMSEC和RMSEP值分别为0.0829和0.107质量％。所提出的用于预测总硫和TCAN的方法是快速，高效且具有成本效益的，并且与标准方法相比具有多个优势。