Product

Main Product: Hydrocarbon gas liquids
Segment: Refined Products
Main-Family: Refinery Liquids
Sub-Family: Light Distll. & Proc. Hydroc.
Physical State: Liquid

Product

Raw LPG

Abbreviation

LPG

Names

Sour LPG; Unseweetened LPG; LPG (raw); Sour Liquefied Petroleum Gas

Production

Global Production Production Map

Raw LPG (Liquefied Petroleum Gas) is a mixture of propane, butane and iso-butane and lighter hydrocarbons, typically accompanied by sulfur-containing impurities such as hydrogen sulfide and mercaptans, water, and other contaminants. It is produced during initial processing steps—such as natural gas processing or from the overhead streams of condensate splitters and stabilizers at refineries—before any purification or sweetening treatments are applied. Olefins (including butylene and propylene) are often present in raw LPG derived from certain refinery processes (e.g., FCC units or steam crackers). In the context of refinery and gas plant operations, raw LPG refers to the unprocessed or partially processed LPG stream obtained directly from the fractionation or stabilization units, and its variable contaminant content can include both sulfur compounds and other trace impurities.

Raw LPG is unsuitable for direct commercial use due to these impurities, which can cause operational hazards, odor issues, and equipment corrosion. To make the product safe and marketable, raw LPG requires further downstream conditioning—most commonly via a Merox or similar sweetening unit—to remove sulfur species and meet regulatory and commercial specifications for odor, corrosivity, and safety. During hydrotreating and sweetening, which are commonly used for “refined” or “sweetened” LPG, many of the olefins are hydrogenated to paraffins (alkanes), especially if the end-use market requires low or no olefin content. The sweetening process (e.g., Merox) primarily removes sulfur compounds but may be paired with hydrotreating if significant olefins are present and product specification demands are stringent.

Chemical Data

Property	Value
Chemical Formula	Variable (mixture of C₃H₈, C₄H₁₀, with traces of C₂–C₅, plus impurities)
Molecular Weight	44–58 g/mol (propane: 44.10, n-butane: 58.12, blend depending on ratios)
Freezing Point (°C)	Below −135°C (propane freezes at −187.7°C, butane at −138.4°C; mixture is lower)
Boiling Point (°C)	−0.5°C to −42°C (range from n-butane: −0.5°C, to propane: −42°C)
Melting Point (°C)	Below −135°C (as above; mixture does not have a strict melting point)
Sulfur Content (wt%)	Typically 0.01–0.2 wt% (can range up to 0.5 wt% for raw/sour LPG)
Specific Gravity	0.50–0.58 at 15°C (air=1.0; depends on propane/butane ratio)
Conversion Factor	1 tonne ≈ 1.96 m³ (density ~510 kg/m³; slight variation by composition)

Notes

All data provided above is specific to unsweetened/raw LPG—prior to any sweetening, purification, or intentional blending to achieve commercial (sweet) LPG standards.
Exact properties will depend on local feedstock and fractionation conditions; ranges are typical for refinery-gas-plant unsweetened LPG streams.

References

ECHA Substance Information (CAS 68476-85-7)
UOP, API, and chemical industry technical literature
"Liquefied Petroleum Gas Properties Handbook," Gupta, H.P., McGraw-Hill
Refinery process engineering manuals; U.S. EPA AP-42 Emission Factors for Petroleum Industry

Identifiers

CAS Number: 68476-85-7
EC Number: 270-704-2
ECHA InfoCard: 100.064.257
IUPAC Name: Liquefied petroleum gas (unsweetened); propane/butane mixture
PubChem ID: 6366

Chemical Data

Chemical Formula: Variable (mixture of C₃H₈, C₄H₁₀, with traces of C₂–C₅, plus impurities)
Molecular Weight (g/mol): 52
Freezing Point (°C): -160
Boiling Point (°C): -20
Sulfur Content (wt%): 0.2
Specific Gravity: 0.54