Black smoke billows as firefighters battle the chemical plant blaze in Zhangzhou, Fujian province, on Tuesday in which at least 19 people were injured. [Photo / Xinhua]

The PX plant on the Gulei Peninsula in Zhangzhou, Fujian, has an annual capacity of 1.6 million tons.

It was originally planned to be built in the coastal city of Xiamen in the same province, but was relocated to Zhangzhou after thousands took part in a protest in 2007.

Media reported that the project had started construction before it got environmental impact assessment approval and was fined by the authorities in 2013.

China's PX projects are mainly dominated by the two oil giants－China National Petroleum Corp, the country's largest oil and gas producer, and Sinopec Group, Asia's biggest refiner. The two companies account for around 80 percent of the nation's total PX output.

Facing the growing demand and supply shortage of PX in the country, some private companies are stepping into the area.

In February, Baota Petrochemical Group, a private oil refining and petrochemical company based in the Ningxia Hui autonomous region, signed an agreement with the United States-based company UOP LLC and introduced the technology for aromatic hydrocarbon production lines from the latter.

Sun Hangchao, board chairman of Baota Petrochemical, said it is the best choice for the company to employ the production line to further develop downstream chemical businesses.

If the cooperation goes well, Baota Petrochemical will become the second private Chinese company that produces paraxylene, following Fujia Group, headquartered in Dalian, Liaoning province.

PX plants are highly controversial in China, and proposed plants met strong public opposition in recent years.