Abstract: In order to produce national VI diesel and meet the requirement of long-term operation of the unit, SINOPEC Hainan Refining and Chemical Company, Limited. upgraded the 2.48Mt/a diesel hydroupgrading MHUG-II unit, added a new refining reactor, regenerated the first-cycle used catalyst, adopted RS-2100 hydrorefining catalyst, and optimized the gradation of RG series protective catalysts. The calibration results showed that the density of diesel products was 0.843 4 kg/m3, the cetane number was 51.6, the sulfur content was 2.3μg/g, the polycyclic aromatic hydrocarbons content was 3.4% （mass fraction）, and the total pollutant content was 5 μg/g, all of which met national VI diesel standards. From January 23, 2018 to April 30, 2019, the unit flexibly produced national V/VI diesel oils for 463 days. The average deactivation rates of refining and hydroupgrading catalysts were 0.029 ℃/d and 0.015 ℃/d, respectively. The average deactivation rates of refining reactor I and II catalysts were 0.027 ℃/d and 0.012 ℃/d, respectively. The total life cycle of each catalyst satisfied with the target of 4-5 years maintenance requirements.

Key words: MHUG-Ⅱunit, quality upgrading, process revamping, national VI diesel