How to determine the acidity and acid number of petroleum products?

How to determine the acidity and acid number of petroleum products?

Acidity and acid number of petroleum products are key indicators for measuring their corrosiveness and quality stability. Determination methods and standards are as follows:

I. Definition and Difference

‌Acid Number‌

Defined as the milligrams of potassium hydroxide (KOH) required to neutralize 1 gram of petroleum product, with the unit mgKOH/g, reflecting the total content of organic acids in the oil.

‌Acidity‌

Expressed in mgKOH/100mL, applicable to water-soluble samples (such as gasoline, diesel), with the same principle as acid number but a different unit.

II. Determination Methods

‌Potentiometric Titration Method‌

‌Standard‌: GB/T 7304-2000 (equivalent to ASTM D664)

‌Characteristics‌: Suitable for colloidal, turbid, or dark oils, determining the endpoint via potential changes, with high precision but complex equipment.

‌Indicator Titration Method‌

‌Standards‌:

GB/T 264-1983 (boiling ethanol extraction, KOH ethanol titration)

GB/T 4945-2002 (toluene-isopropanol mixed solvent)

‌Steps‌:

Acidic component extraction (dissolved in boiling ethanol)

Neutralization titration (using alkaline blue 6B or cresol red indicator)

Calculation: $ X = 56.1 times V times N / G $ (V = titration volume, N = concentration, G = sample weight)

‌Semi-micro Method‌

‌Standard‌: SH/T 0163, with a lower detection limit.

III. Instruments and Reagents

‌Instruments‌: Conical flask, reflux condenser, micro burette.

‌Reagents‌: 0.05 mol/L KOH ethanol standard solution, 95% ethanol, indicators (alkaline blue 6B/cresol red).

SH108 automatic oleic acid level meter complies with the requirements stipulated in the People's Republic of China standard GB/T 264 "Determination of the acid value of petroleum products" and GB7599,

The instrument adopts blue LCD large screen display, Chinese menu, no marker button.

using the principle of titration and neutralization method, under the control of the microcomputer automatically complete liquid injection, titration, mixing, determination of neutralization and titration end point, LCD screen display the measurement results, and automatically print the measurement results.

The measurement process takes seven minutes.

Special reagent bottles are used to hold the extraction liquid and neutralizing liquid, and the reagent is isolated from the air during use to avoid the influence of volatilization and carbon dioxide in the atmosphere.

At the same time also play a role in protecting the operator.

automatic acid value tester can choose a test of 6 oil samples.