Citgo Petroleum has completed the construction and start-up of a major processing unit to produce ultra-low-sulfur diesel (ULSD) at its Lemont, Ill., refinery.

The unit is equipped with the latest technology designed to reduce, by 98 percent, the sulfur content of diesel transportation fuel produced at the refinery.

The new unit has a production capacity of 42,500 barrels per day of ULSD, which constitutes the majority of Lemont's overall distillate production of 55,000 BPD refined from heavy crude. The steps involved in producing ULSD include adding hydrogen to remove the sulfur from the diesel and then recovering and converting those sulfur compounds into elemental sulfur. This is then sold into the fertilizer market, an additional step in the company's commitment to the environment.

The Citgo Lemont Refinery will now be able to produce 100 percent ULSD, in addition to other refinery products such as gasoline, jet fuel and other specialty middle distillate products. The Lemont refinery produces fuels for a large portion of the network of nearly 6,500 locally owned Citgo stations across the country.

In addition to Lemont, the Citgo Corpus Christi, Texas, refinery will soon introduce their own upgraded ULSD facility that will be able to produce 100 percent ULSD. The Citgo Lake Charles Manufacturing Complex in Louisiana has been producing ULSD since 2006.