离子色谱法测定醇胺脱硫溶液中热稳定盐

为了控制热稳定盐(HSS)对天然气净化装置造成的危害,建立了一种同时检测醇胺脱硫溶液中的乙酸根离子、甲酸根离子、氯离子、硫酸根离子、草酸根离子、硫代硫酸根离子和硫氰酸根离子的离子色谱方法。该方法利用膜过滤、反相固相萃取和稀释3个步骤对工业样品进行前处理,采用氢氧化钾梯度淋洗和电导检测的方式,实现了7种离子的分离与检测。方法的线性范围为0.01～0.5 mmol/L,检出限(以信噪比(S/N)为3计)小于0.1 mg/L,回收率为80.0%～100.3%。在5个不同添加浓度下分别测定了上述7个离子,色谱峰面积的重复性良好(相对标准偏差(RSD, n=10)为0.94%～3.99%。通过3个实验室比对试验,表明该方法再现性良好,色谱峰面积的RSD小于5%。应用该方法成功地检测了8家天然气净化厂、3家石油炼厂和1家煤制油工厂的脱硫溶液样品中的HSS,并连续监测某天然气净化装置15 d。该方法具有良好的可靠性和实用性。

Determination of heat stable salt anions in alkanolamine desulphurization solution by ion chromatography

To control the potential risk of natural gas purification plants, an ion chromatographic method has been developed to determine the heat stable salts (HSS) in alkanolamine desulphurization solution. Seven HSS anions, including CH3COO(-), HCOO(-), Cl(-), SO4(2-), C2O4(2-), S2O3(2-), SCN(-), were determined in a single injection. Before the chromatographic analysis, these industrial samples were pretreated by three steps, i.e. filtration, solid phase extraction and dilution. Using the gradient elution with KOH solution, all of the seven anions have been separated and determined by a conductivity detector. As the calibration results, the linear range of this method was 0.01 - 0.5 mmol/L for the 7 anions. The limit of detection (LOD, S/N = 3) was 0. 1 mg/L for each anion. By spiked standard solutions in the samples, the recoveries were in the range of 80.0% - 100.3%. The repeatability of this method was evaluated at five different concentrations. The relative standard deviations (RSD, n = 10) of the peak areas were in the range of 0.94% to 3.99%. Moreover, the reproducibility of the method was also tested in three different laboratories and it was acceptable with the RSD <5%. The proposed method has been applied to the determination of HSS in eight gas purification plants, three oil refineries and one coal gas plant and to monitor a gas purification plant continuously in 15 days. It's shown that the accuracy and precision of this method are satisfactory.