There is one important link in the technology chain of the delayed coking complex (DCC) that will provide additional production to the Naftan plant.

It is a unit for purification of liquefied hydrocarbon gases DCC from mercaptans (active sulphur compounds) MEROX. In the liquefied hydrocarbon gas, mercaptan compounds are represented by methyl and ethyl (CH₃SH and C₂H₅SH). The mercaptans are highly corrosive compounds and must be removed from the process or converted to other less aggressive organic compounds. This unit occupies an area of almost 18,000 square metres, harmoniously complementing the industrial landscape in the south-western part of the Naftan plant - close to the new hydrogen production unit.

UNIS was in the position of main designer and contractor. The design and budget documentation for the project (Basic design and Detail design) was prepared, an engineering survey and a site visit were carried out. The project was implemented under the UOP license. Detail design and detailed specifications for the purchase of equipment and materials were completed in 2020. In the same year, the entire delivery of the mechanical and process equipment and much of the material for installation was completed. In the first quarter of 2021, the remainder of the material for assembly was delivered. The customer successfully carried out the implementation of the machinery and assembly work in cooperation with UNIS in the form of author's supervision. Completion of the assembly work and commissioning of the MEROX unit for trial operation took place at the end of 2021.

In fact, a "second" MEROX was built in Naftan. The first MEROX unit, which was commissioned at the plant in 1977, purifies the kerosene fraction from mercaptans. This unit fulfils an important production function. It produces Jet A-1 aviation fuel for turboshaft engines, the quality of which meets modern American and European standards.

The new MEROX has its own strategic objectives. Its main production is liquefied petroleum gas (LPG), as a finished commercial fuel for cars or as a household gas. LPG is considered a good alternative to petrol, according to the manufacturers. In terms of quality, the MEROX process reduces the sulphur content of mercaptan in the fuel specification to the required level. Naftan allows the product to be delivered to end users by road, rail and pipeline. The design capacity of the new unit is 19.61 m3/h, or 96,000 tonnes per year.

According to environmentalists, the purification of DCU's liquefied hydrocarbon gases from mercaptans is an ecological project that meets high standards of environmental safety. The waste from the cleaned LPG is disposed of in a special incinerator. An automated emission control system continuously monitors the operation of the incinerator.