AM-01-28 CLEAN FUELS: ROUTE TO LOW SULFUR LOW AROMATIC DIESEL

Description:

A new Environmental Protection Agency (EPA) regulation, effective June 1, 2006, will result in almost exclusive production of 15 wppm sulfur diesel in the USA. Refiners will have to revamp their current distillate hydrotreating units or build new units to meet this upcoming regulation. Revamps might include the use of more active hydrodesulfurization catalysts together with unit modifications such as catalyst dense loading, increase of catalyst volume by adding a reactor, replacement of reactor internals, adding a H2S scrubber and increasing the hydrogen purity of the recycle gas loop. New catalysts have been developed recently which have a higher desulfurization activity for ultra-low sulfur diesel. To reach this ultra low sulfur target, the revamped or new diesel units will have to operate at low space velocities and moderately high pressures. At these operating conditions, most of the time, high hydrogenation activity NiMo catalysts provide a better desulfurization performance than CoMo catalysts. Commercial experience exists for the production of this ultra-low sulfur diesel product, as shown in the first-stage of existing HDS/HDA diesel units. New dearomatization catalysts (noble-metal) with much higher activity have been recently commercialized to reduce the aromatics and improve the Cetane Index.