Propylene

Propylene is the second-largest olefin, a three-carbon molecule whose biggest job is becoming polypropylene, the plastic of car parts, food packaging, appliances, and medical equipment. Global demand is roughly 130 million tonnes a year. Historically propylene was a byproduct: refineries made it in fluid catalytic crackers as a side effect of gasoline production, and naphtha steam crackers made it as a co-product of ethylene. Nobody built a plant just to make propylene, because the byproduct streams were enough.

Shale broke that arrangement. As US and Middle East crackers shifted to ethane, which yields almost no propylene, the co-product supply stopped growing while polypropylene demand kept compounding. The answer was on-purpose production, dominated by propane dehydrogenation: a PDH plant strips two hydrogen atoms from propane to make propylene directly. China built the technology out at extraordinary scale, with PDH capacity exceeding 20 million tonnes a year by 2025, designed largely around imported US propane. The buildout overshot; Chinese PDH operating rates fell below 75 percent and margins spent much of 2024 and 2025 negative, yet plants kept running to hold market share and feed integrated polypropylene lines.

Pricing centers on polymer-grade propylene, PGP. In the US, PRA-assessed Mont Belvieu PGP sets monthly contract prices, and CME lists a cash-settled PGP futures contract against OPIS PetroChem Wire assessments that has become the most active petrochemical future in the West, though still small next to energy contracts. Asia trades CFR China cargoes assessed by S&P Global and ICIS, with PDH economics, the spread of propylene over propane, as the most watched margin in the complex.