Product

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

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

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