Low sulfur and low aromatics diesel fuel are required to reduce air pollution. This high quality fuel can be produced by a high active catalyst RN-1 or a novel MHUG process (Medium Pressure HydroUpgrading) developed by RIPP, depending on the properties of the feedstocks.

RN-1 has been widely applied in 24 units in China for various feedstocks since 1987. It has a high activity of HDS, HDN and aromatic saturation and can produce the desired diesel fuel from AGO or LCGO under medium pressure (6.4 MPa). But for other feedstock, like FCC-LCO, higher pressure must be used.

Chemical analysis indicates that hydrocracking under medium pressure is an effective way to further reduce the aromatics in diesel fuels. The combination of a hydrotreating catalyst and a hydrocracking catalyst could produce high quality diesel fuels from FCC-LCO. Based on this principle, the MHUG process was developed.

The MHUG process has been applied commercially for FCC-LCO in the Daqing Petrochemical Complex since Oct. 1992. Under the pressure of 8.0 MPa, the sulfur content of the diesel fraction produced is< 0.05 wt%, the aromatics content < 20 vol% and the cetane number is as high as 70. Meanwhile feedstocks for reforming, FCC or steam cracking could be obtained.

Environment pollution is a concern of the world.

The emission from the combustion of motor fuels is one of the pollution sources. Sulfur, nitrogen and aromatics are the main contributors. The more stringent limitation of their content in fuels is now mandated in some countries','. On the other hand, more sour and heavier crudes are running now in the petroleum industry resulting in more S, N and aromatics in the products. In order to meet the new fuel specifications, extensive studies have been done by many companies.

RN-1 catalyst was developed by RIPP to meet these contradictory challenges and have been successfully applied in commercial units3. Its excellent hydrogenation activity makes it a candidate for the production of low S/low aromatics diesel fuel. The data in a pilot plant showed in Table 1 indicated that high quality diesel fuel could be produced from AGO and LCGO under medium pressure.

In general, the aromatics content of AGO and LCGO were usually <30 vol%. A low S/low aromatics diesel fuel can be produced from AGO or TABLE 1 Hydrotreating results of AGO, LCGO and LCO with RN-i Feedstock and prod. AGO Prod. LCGO Prod. LCO Prod.

Conditions: PH, MPa 3.2 5.9 12.0 Temp., "C 320 340 360 LHSV, h- 3.0 2.0 1 .o H,/Oil, v/v 300: 1 350: 1 350: 1 Density (20 OC), g/cm' 0.8110 0.8079 0.8364 0.8130 0.8930 0.8380 s, wt PPm 1200 21 6700 18 5401 70

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