Method for quickly measuring acid value of lubricating oil by thermometric titration

Abstract

The invention discloses a method for quickly measuring acid value of lubricating oil by thermometric titration, and belongs to a method for measuring acid value of lubricating oil. According to endothermic or exothermic effect in a chemical reaction, after an end point of a titration system is reached, excess titration solution is subjected to instantaneous endothermic or exothermic chemical reaction with temperature indicating liquid in a sample system so that the temperature of the titration system is remarkably reduced or raised so as to easily judge a titration end point. Particularly, the method comprises the following steps: weighing a lubricating oil sample, a solvent and the temperature indicating liquid, adding the three substances into a heat-insulated reaction container in a thermometric titration device, stirring the mixture to make the lubricating oil sample fully dissolved in the mixed solvent, keeping temperature constant, then using 0.1mol / L potassium hydroxide-isopropanol standard titrating solution to titrate the mixed solvent, using read numbers of a temperature sensor to draw a graph of the volume of the titrating solution, taking a jump point of a curve as a titration end point, and calculating the acid value of the lubricating oil sample. The method has the advantages of short detection time, accurate detection result, little error and low toxicity.

Description

technical field [0001] The invention relates to a method for measuring the acid value of lubricating oil. Specifically, it is a rapid determination method of lubricating oil acid value temperature titration. Background technique [0002] Acid value refers to the number of milligrams of potassium hydroxide (KOH) required to neutralize the acidic components in 1 gram of lubricating oil, usually expressed in mgKOH / g. The acidic substances contained in lubricating oil mainly refer to organic acids (such as naphthenic acid, fatty acid, phenolic compounds, asphaltic acid, mercaptan, etc.), inorganic acids (acidic sulfuric acid ester, sulfonic acid, etc.), colloids, Heavy metal salts, ammonium salts and acid salts of polybasic acids, etc. These substances are not only inherent in crude oil, but also produced under storage and use conditions, and even include additives and their change products. On the one hand, by measuring the acid value of the lubricating oil, the content of a...

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Problems solved by technology

However, it is difficult for this method to have potential mutations in the determination of non-aqueous systems, and the measurement effect is relatively poor.

In addition, the electrode system used in potentiometric titration needs to be calibrated and maintained, and various non-aqueous buffer solutions need to be prepared before the measurement. hazards to health and the environment

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