SH/T 0092-1991 Petroleum acid test method

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Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: SH/T 0092-91 (confirmed in 2000)
• Chinese name: Petroleum acid test method
• English name: not provided in the available source
• Replacement relationship: replaces SY 2911-77 (confirmed in 1988)
• Approval/implementation: approved by China Petrochemical Corporation 1991-11-26, implemented on 1992-12-01

2. Scope of application and non-applicability

• Scope of application: This standard specifies the determination of the crude acid value and pure acid value of petroleum acids and the calculation methods for petroleum acid content and mineral oil content; it is applicable to the determination of petroleum acids extracted from petroleum fractions.
• Not applicable: not provided in the available source.

3. Method principle

The sample is titrated with a potassium hydroxide-ethanol standard titration solution using freshly neutralized 95% ethanol as the solvent and phenolphthalein as the indicator to determine the crude acid value and pure acid value, and then the petroleum acid content and mineral oil content are calculated by formulas. (Original 4 method summary)

4. Reagents and materials (purity / preparation)

• 6.1 Petroleum ether: analytical reagent, 30–60 ℃ or 60–90 ℃.
• 6.2 Sodium chloride: analytical reagent, prepared as a saturated aqueous solution.
• 6.3 95% Ethanol: analytical reagent.
• 6.4 Nitric acid: analytical reagent, prepared as a 10% (m/m) aqueous solution.
• 6.5 Potassium hydroxide: analytical reagent, prepared as a c(KOH)=0.1000 mol/L potassium hydroxide-ethanol standard titration solution.
• 6.6 Methyl orange indicator: prepared as a 0.2 g/L indicator solution.
• 6.7 Phenolphthalein indicator: prepared as a 10 g/L ethanol indicator solution.
• 7.1 Preparation of potassium hydroxide ethanol-water solution: prepared from 56 g/L potassium hydroxide-ethanol solution and water in a volume ratio of 1:1.

5. Instruments and equipment

• 5.1 Conical flask: 100 or 150 mL.
• 5.2 Separatory funnel: 250 or 500 mL.
• 5.3 Burette: 10 or 25 mL.
• 5.4 Beaker: 100 or 150 mL.

6. Recommended operating conditions

• Titration solvent: freshly neutralized 95% ethanol.
• Indicator: phenolphthalein indicator solution.
• Titrant: c(KOH)=0.1000 mol/L potassium hydroxide-ethanol standard titration solution.
• End point: the solution appears light rose red.
• Drying of pure acid value sample: dry at 105~110 ℃ for 1 h.
• Washing of crude acid value sample: wash with about 70 ℃ distilled water until neutral.
• Other recommended operating conditions: not provided in the available source.

7. Sampling and sample preparation

• 7.2 Preparation of pure acid value sample
  • 7.2.1 Take 5~10 mL petroleum acid sample, place it in a separatory funnel, add a few drops of phenolphthalein indicator solution, then add potassium hydroxide ethanol-water solution and shake thoroughly until an obvious alkaline reaction appears.
  • 7.2.2 Add 15~20 mL (for heavy petroleum acids, 30 mL is allowed) petroleum ether to the separatory funnel and shake it to extract the mineral oil in the sample. After standing and layering, collect the lower ethanol-water soap solution in a clean container, and repeatedly extract with the same volume of petroleum ether (about four times) until a drop of petroleum ether on filter paper no longer leaves an oil trace when observed against the light.
  • 7.2.3 To the deoiled ethanol-water soap solution, add a few drops of methyl orange indicator solution, and while continuously shaking, add 10% (m/m) nitric acid aqueous solution to make it show an obvious acidic reaction (for dark-colored petroleum acids, pH1 test paper may be used for testing).
  • 7.2.4 After standing and layering, discard the aqueous layer. Repeatedly wash the upper petroleum acid with saturated sodium chloride aqueous solution until neutral, then wash once with distilled water. Or only wash with about 70 ℃ distilled water until neutral.
  • 7.2.5 Place the washed petroleum acid in an oven, dry at 105~110 ℃ for 1 h, then cool to room temperature, and weigh this sample to determine the pure acid value.
• 7.3 Preparation of crude acid value sample: petroleum acid not deoiled of mineral oil is washed with about 70 ℃ distilled water until neutral, and used as the sample for determining the crude acid value.

8. Analytical procedure

• 8.1 Determination of crude acid value and pure acid value: weigh the sample (from clause 7.2 or clause 7.3) 0.3~0.5 g (accurate to 0.0002 g) into a 100 mL conical flask, add 25 mL freshly neutralized 95% ethanol and a few drops of phenolphthalein indicator solution, titrate with c(KOH)=0.1000 mol/L potassium hydroxide-ethanol standard titration solution until the solution appears light rose red, and record the volume of potassium hydroxide-ethanol standard titration solution consumed.
• 8.2 Determine the water content of the test sample according to GB/T 260.

9. Qualitative and quantitative determination and calculation formulas

• 9.1 The crude acid value X₁ or pure acid value X₂ of the test sample (mg KOH/g) is calculated according to formula (1):
  • X (or X) = c·V×0.056×1000 / m = c·V×56 / m … (1)
  • Where: c—— the actual concentration of the potassium hydroxide-ethanol standard titration solution, mol/L;
  • V—— the volume of potassium hydroxide-ethanol standard titration solution consumed when titrating the crude acid value or pure acid value, mL;
  • m—— the mass of the sample, g;
  • 0.056—— the mass, expressed in grams, of crude acid or pure acid (expressed as potassium hydroxide) equivalent to 1.00 mL potassium hydroxide-ethanol standard titration solution [c(KOH)=1.000 mol/L].
  • Note: The symbols and coefficients in the original formula (1) contain source-text extraction noise (such as “•½” “£•K”); the above is organized according to context and requires confirmation against the source standard (source-text extraction).
• 9.2 The petroleum acid content X₃ [% (m/m)] of the test sample is calculated according to formula (2):
  • X₃ = (X₁ - X₂)/X₁ × 100 … (2)
  • Where: X₁ — the crude acid value of the test sample, mg KOH/g; X₂ — the pure acid value of the test sample, mg KOH/g.
  • Note: In the original formula (2), source-text extraction is “8-N×100”; the numerator part requires confirmation against the source standard (source-text extraction).
• 9.3 The mineral oil content X₄ [% (m/m)] of the test sample is calculated according to formula (3):
  • X₄ = 1 - (X₃ + X₅) … (3)
  • Where: X₃ — the petroleum acid content of the test sample, % (m/m); X₅ — the water content of the test sample, % (m/m).
  • Note: In the original formula (3), subscripts such as “Xs” and “Xa” are source-text extraction confused and require confirmation against the source standard (source-text extraction).

10. Precision

• 10.1 Repeatability: the difference between two results obtained by repeated determination by the same operator shall not exceed 1% of the arithmetic mean.
• 10.2 Reproducibility (provisional): the difference between two results submitted by different laboratories shall not exceed 2% of the arithmetic mean.

11. Report

Take the arithmetic mean of two results from repeated determinations as the determination result.

12. Referenced documents

• GB/T 260 Determination of water in petroleum products

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference Q&A