Koch Industries, the Wichita-based conglomerate controlled by the billionaire Koch brothers, has agreed to take private a petrochemical plant owner whose operations are geared toward converting shale gas into plastics.

The terms of the transaction—which is valued at $2.1 billion, including assumed debt, call for Houston-based PetroLogistics LP to be acquired by Koch affiliate Flint Hills Resources. PetroLogistics owns a 67-acre propane dehydrogenation plant in Houston that makes propylene, a chemical used to produce polypropylene, a polymer used in packaging, labels and textiles.