Flint Hills Resources, part of the empire of Wichita, Kansas-based Koch Industries, has completed the $2.1 billion all-cash acquisition of Houston, Texas-based PetroLogistics LP and its general partner PetroLogistics GP.

The deal marks the largest acquisition in the history of the US company owned by the politically active Koch Brothers, David and Charles, two of the world's richest men. It is also the largest acquisition since the brothers bought Huntsman's US commodity chemical business in 2007.

The acquisition was finalized through the merger of Flint Hills Resources' subsidiary, FHR Propylene, into PetroLogistics. Flint Hills earlier said it planned to delist its new acquisition, a major producer of propylene and derivatives.

With revenue of $757.5 million and 100 employees in 2013, PetroLogistics processes natural gas, an increasing amount shale derived, in the world's largest-capacity propane dehydrogenation (PDH) plant, in the Houston Ship Channel. The PDH facility will be integrated into Flint Hills'chemical and refining business.