Sinopec Engineering (Group) Co has won an 18.67 billion yuan (US$3.1 billion) contract to build one of the world’s largest coal-to-chemical projects in north China.

The company, a unit of Asia’s top refiner Sinopec Group, will be responsible for the engineering, procurement and construction of the project for Zhong Tian He Chuang Energy Corp, Sinopec Engineering said in a Hong Kong stock exchange filing.

Zhong Tian He Chuang is 38.75 percent owned by Sinopec Corp, the flagship listed unit of Sinopec Group.

Upon completion, the complex in Uxin Banner in Ordos, the Inner Mongolia Autonomous Region, will annually produce 3.6 million tons of olefins — mainly ethylene or the key petrochemical building block. It will be the biggest coal-to-olefin complex in the world, Sinopec Engineering said.

The project will use Sinopec’s self-developed technology known as SMTO to produce olefins from methanol, which can be extracted from coal.