🧫 Distillation of Petroleum Products
Determination of fractional composition (distillation curve) of light and middle petroleum distillates at atmospheric pressure in temperature range 0–400°C.
Overview
Atmospheric distillation is one of the oldest and most important methods for characterizing petroleum products. It allows determination of fuel fractional composition — the distillation curve (temperature vs. percent volume evaporated) provides key information about volatility, chemical composition and fuel behavior under operating conditions.
For motor gasolines, the evaporation temperature at 10% (T₁₀) affects cold start ease, T₅₀ affects warm-up speed and acceleration, and T₉₀ and FBP (final boiling point) affect deposit formation in combustion chamber and lubricating oil dilution. For diesel fuel, distillation temperatures affect ignition quality (cetane index), particulate emissions and low-temperature behavior.
The method involves heating 100 mL sample in a standardized distillation flask at a defined rate. Fuel vapors pass through a tubular condenser, condense and collect in a graduated cylinder. Temperature in flask neck is recorded as a function of collected distillate volume. Key curve points are: IBP (initial boiling point), T₁₀, T₅₀, T₉₀, FBP (final boiling point), recovery and residue.
The standard covers light and middle distillates with IBP above 0°C and FBP below approx. 400°C — gasolines, jet fuels, diesel oils, light fuel oils and naphthas. Manual or automatic apparatus may be used; in case of dispute, manual method is preferred.
Method principle
100 mL sample is measured with graduated cylinder and transferred to a distillation flask of standardized dimensions (125 mL flask with side arm). Flask is heated electrically (1000 W heater with stepless regulation). Vapors pass through tubular condenser maintained at 0–60°C (depending on product group). Distillate collects in graduated cylinder placed in cooling bath. Temperature of thermometer in flask neck is read at moment of evaporation of each 5 or 10% volume. Temperatures are corrected to 101.3 kPa pressure. Results are presented as distillation curve or table.
Applications
- Quality control of motor gasoline — fractional composition per PN-EN 228
- Quality control of diesel fuel — distillation per PN-EN 590
- Testing of jet fuel Jet A-1 — distillation per DEF STAN 91-091
- Calculation of cetane index (ISO 4264) — T₁₀, T₅₀, T₉₀ as input data
- Evaluation of kerosene and light fuel oils
- Monitoring refinery processes — control of fraction cut temperature
- Testing petroleum solvents and paint thinners
Key parameters
| Parameter | Value |
|---|---|
| Temperature range | IBP > 0°C, FBP < ~400°C |
| Sample volume | 100 mL |
| Product groups | Group 0: LPG; 1: gasolines; 2: kerosenes; 3: diesel; 4: blends |
| Repeatability (T₅₀) | ±1.5°C (gasoline), ±2.5°C (diesel) |
| Reproducibility (T₅₀) | ±4.3°C (gasoline), ±5.6°C (diesel) |
| Determination time | 30–60 min |
Standard
- Standard number
- PN-EN ISO 3405:2019
- Title (PL)
- Przetwory naftowe i produkty pokrewne pochodzenia naturalnego lub syntetycznego — Oznaczanie składu frakcyjnego metodą destylacji pod ciśnieniem atmosferycznym
- Title (EN)
- Petroleum and related products from natural or synthetic sources — Determination of distillation characteristics at atmospheric pressure
Step-by-step procedure
1. Product group identification
Determine product group: Group 1 — gasolines (IBP <100°C), Group 2 — kerosenes and Jet A-1, Group 3 — diesel (T₁₀ >150°C), Group 4 — blends. Select appropriate cooling conditions and distillation rate.
2. Apparatus preparation
Mount clean distillation flask. Connect condenser with appropriate cooling water flow. Place thermometer in flask neck at proper height. Position graduated cylinder under condenser outlet.
3. Sample measurement
Measure 100 mL sample with graduated cylinder at ambient temperature. Record sample temperature. Transfer quantitatively to distillation flask.
4. Distillation start
Turn on heater. Regulate heating power to achieve appropriate distillation rate (first distillate drop should appear in required time: 5–15 min for Group 1).
5. IBP reading
Record thermometer temperature at moment first drop of distillate falls from condenser end (Initial Boiling Point). Correct to 101.3 kPa.
6. Distillation curve recording
Record temperature at each 5% or 10% volume recovery. Distillation rate: 4–5 mL/min (Groups 1 and 2) or 4–5 mL/min (Group 3). Record as pairs: volume — temperature.
7. FBP and end of distillation reading
Record maximum temperature reached during distillation (FBP — Final Boiling Point). Turn off heater. Wait for last distillate drops.
8. Recovery and residue measurement
Read distillate volume in cylinder (recovery). Pour residue from flask into 5 mL graduated cylinder — measure residue volume. Loss = 100 - recovery - residue.
9. Barometric correction
Correct all temperatures to 101.3 kPa pressure using formula: ΔT = 0.0009 × (101.3 - p) × (273 + T), where p in kPa, T in °C.
10. Distillation curve preparation
Prepare table and graph: temperature (°C) vs. percent volume evaporated (%). State IBP, T₁₀, T₅₀, T₉₀, FBP, recovery, residue, loss.
11. Apparatus cleaning
After flask and condenser cooling — rinse with acetone. Dry. Check flask condition (no cracks, carbonization deposits).
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Automatic distillation apparatus | Normalab NDI 450, PAC OptiDist, Koehler K45703 | 50 000–120 000 PLN |
| Manual distillation apparatus | Koehler K45000 Front View Distillation | 15 000–35 000 PLN |
| Distillation flask 125 mL | Glass flask per ISO 3405 with side arm | 80–200 PLN/pc |
| Tubular condenser | Metal condenser with regulated cooling water flow | 2 000–5 000 PLN |
| Graduated cylinder 100 mL | Glass cylinder class A with 1 mL graduation | 100–300 PLN |
| Thermometer/temperature sensor | ASTM thermometer or Pt100 sensor with 0.1°C resolution | 500–2 000 PLN |
| Barometer | Digital barometer for result correction | 800–2 500 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Distillation CRM (gasoline) | — | Certified reference material with known distillation curve, e.g., Paragon Scientific Gasoline Distillation Standard |
| Distillation CRM (diesel) | — | Certified diesel fuel standard with known distillation curve |
| Acetone (for cleaning) | 67-64-1 | Purity ≥99.5%, for rinsing flask, condenser and cylinder |
| Antifoam agent (optional) | — | Silicone oil, few drops for samples prone to foaming (biodiesel) |
| Boiling stones (optional) | — | Porcelain or carborundum, prevent bumping |
Health and safety (OHS)
- Petroleum fuels — highly flammable, distillation conducted in fume hood
- Hot distillation flask (up to 400°C) — risk of severe burns, heat-resistant gloves
- Fuel vapors — toxic and flammable, exhaust ventilation mandatory
- Risk of bumping — boiling stones, careful heating power regulation
- CO₂ extinguisher within reach
- Safety glasses, flame-retardant coat, gloves mandatory