摘要
采用付立叶变换红外光谱仪,跟踪测定了四种汽轮机油在ASTM D943氧化评定过程中不同氧化时间点的油样。油样用四氯化碳稀释定容,液膜法测定,扫描128次,图谱进行局部放大,主要研究在1615～1800cm^(-1)(中心在1715 cm^(-1))的羰基吸收峰。用参考点法量出各油样的羰基吸光值,换算成单位浓度(1g/mL)的油样羰基吸光值,考察单位浓度油样的吸光值与氧化时间之间的关系,並与酸值与氧化时间的关系对照,发现两者同步增长,且红外测定法测定终点突变明显、精确度高、操作方便、快速、油品用量少、便于跟踪,故有可能用以代替酸值测定法对ASTM D943氧化实验进行评定。
IR absorption of turbine oil samples of four types taken at different times inthe process of ASTM D943 oxidation evaluation was studied by FT-IR spectroscopy., Eachoil sample was diluted to a fixed volume with carbon tctrachloridc(A. R. Grade), Its absorbancewas measured by liquid membrane method and scanning was made 128 times. The spectrumin the region of 1 615～1 800 cm^(-1) has been magnified. The absorbance of carbonyl groupof oil solution at 1 715 cm^(-1) was determined by reference point method, and the value deter-mined was converted to absorbance per unit concentration (1 g/mL) of oil solution. It wasfound that the absorbance after conversion is closely related to the oxidation time. As oxi-dation proceeds, the IR absorption at 1 715 cm^(-1) increases. It is significant that the relationbetween IR absorbance per unit concentration of oil solution and oxidation time appears tobe very similar to that between acid number and oxidation time. Both IR absorbance andacid number increase with oxidation time synchronously. However, IR spectroscopy haslots of advantages: the change at end point is abrupt; the accuracy of measuring is high; theoperation is fast and convenient; the amount of oil sample needed is less than that in acidnumber determination. So, it is possible to replace acid number determination by IR spec-troscopy in ARTM D 943 oxidation evaluation.
关键词
汽轮机油
油质化验
氧化
酸值
羰基
oil assay
infrared spectrometry
oxidation
acid number
petroleum products
carbonyl group
