Mercaptans are acidic sulfur compounds which are naturally present in crude oil. Moreover, a large amount of mercaptans result from the decomposition of other sulfur compounds during crude distillation and cracking operations. All mercaptans have the chemical formula R-SH where R is a hydrocarbon alkyl group, S is a sulfur atom and H is a hydrogen atom.
Mercaptans are undesirable for the following reasons:
- Some of the higher boiling mercaptans found in the kerosene cuts can react with other impurities to generate non-volatile gums. These gums remain inside various reactor parts.
- Mercaptans are acidic corrosive compounds which have to be neutralized to protect engines.
The sweetening process will convert the acidic mercaptans sulfur compounds to neutral disulfides in order to pass the copper strip and doctor test.
Axens Sweetn’K unit is an efficient treatment which enables the standard Jet-A1 specifications to be met with limited investment cost.
Sweetn’K Axens unit is made of 3 sections:
- A front prewash section which neutralizes aliphatic acids.
- The sweetening reaction section where an oxidation reaction converts mercaptans into disulfides. The reaction between mercaptans and air occurs in an alkaline environment in contact with Axens catalyst “SCPS Ready”.
- In the finishing section, the kerosene is dried by a water removal mass and finally upgraded on a clay bed to improve product color.
Axens does not impose any proprietary equipment as extractor trays, mixers, filters, contactors, coalescers and oxidizer internals. This results in a lower initial unit cost and also a lower maintenance cost when replacing such equipment.
The reactor catalyst active material is supported on active carbon. The catalyst is originally supplied in solid form : SCPS Ready – pre impregnated catalyst. SCPS Ready can be regenerated in situ using LCPS 30 liquid catalyst or replaced by fresh SCPS Ready.