Process Technologies

Dimersol-X™

Axens’ Dimersol-X™ process transforms butenes to octenes that are ultimately used in the manufacture of plasticizers via isononanol (isononyl alcohol), and diisononyl phthalate units. Butenes enter the Dimersol-X™ process, which comprises three sections: reactor, catalyst removal and separation.

As shown in the figure, in the reactor section, dimerization occurs in multiple liquid-phase reactors (1) employing homogeneous catalysis and an efficient recycle mixing system. Difasol reactor might be added in order to boost conversion and octene yield through use of ionic liquid. The catalyst is generated in situ by the reaction of components injected in the recycle loop.

The catalyst in the reactor effluent is then deactivated in the neutralization section and separated (2). Section (3) separates unreacted olefin monomer and saturates from the product dimers while the second column (4) separates the octenes. A third column can be added to separate dodecenes.

Dimersol-G™

Axens Solutions Dimersol-G™ process transforms light olefins fractions such as propylene to high quality gasoline called Dimate with low boiling point and high octane properties.

The C₃ feeds are generally the propylene cuts from fluid catalytic cracking units. The Dimersol-G™ process is suitable for isolated refineries without petrochemical outlet for propylene.

FlexEne™

Axens has developed the new FlexEne™ technology to expand the capabilities of the FCC process which is the main refinery conversion unit traditionally oriented to maximize gasoline and at times propylene production.

FlexEne™ is an innovative combination of two well-proven technologies: Fluidized Catalytic Cracking (FCC) and Oligomerization (Polynaphtha™). Combined in an innovative way, they can significantly improve product flexibility to control the balance of propylene, gasoline and diesel production with a low capital investment. This FLEXibility is achieved by selective oligomerization of light FCC alkENEs (olefins) for recycle cracking in the FCC.

By adjusting the catalyst formulation and operating conditions, the FCC process is able to operate in different modes: Maxi Distillate, Maxi Gasoline and High Propylene. This provides the product flexibility required by the market.

PolyFuel®

PolyFuel® technological service is an innovative technology aimed at maximizing middle distillates production by converting light olefins from LPG and gasoline into distillates at minimum cost. PolyFuel® can accept the full range C5-C9 olefinic cut produced downstream of the FCC.

PolyFuel® technology’s objective is to tackle unbalanced gasoline/middle distillates slates while reaching tighter products requirements.

In the PolyFuel® process, light olefins are oligomerized catalytically in two fixed bed reactors in series. Conversion and selectivity are controlled by reactor temperature adjustment while the heat of reaction is simply removed by feed-effluent heat exchange. The reactor section effluent is fractionated producing gasoline depleted in olefins and middle distillates fractions. The gasoline fraction is recycled to the reaction section to enhance middle distillates production.

Selectopol™

The Selectopol™ process is a variant of the Polynaphtha™ process using the same catalyst but at lower severity to convert selectively the isobutene portion of an olefinic C₄ fraction to high octane, low RVP gasoline blending stock or to enrich Trimethyl Pentene stream for petrochemical applications.

Selectopol™ technology provides a low-cost means of retrofitting existing MTBE units or debottlenecking existing alkylation units by converting all isobutene and a small percentage of the n-butenes, with no need for additional isobutane. Selectopol™ is an alternative scheme for alkylation feed preparation without alcohol handling. Selectopol™ technology is also foreseen to avoid or reduce MTBE production in C₄ complex.

Enriched n-butenes raffinate of Selectopol™ is ideally sent to Alkylation, Methyl Ethyl Ketone (MEK), Metathesis or Dimersol-X™ process unit, without any pretreatment.

Polynaphtha™

Polynaphtha™ is one of the indirect alkylation processes upgrading low-value C₃/C₄ cuts from FCC / SC into gasoline and middle distillates by oligomerization of the light olefins contained in the C₃/C₄ cuts.

In the Polynaphtha™ process, propylene and/or mixed butenes are oligomerized catalytically in a series of fixed bed reactors. Conversion and selectivity are controlled by reactor temperature adjustment while the heat of reaction is removed by feed effluent heat exchange and intermediate reactor cooling. The reactor section effluent is fractionated producing LPG raffinate, gasoline and middle distillate fractions such as kerosene or diesel.

The Polynaphtha™ technology is well suited for revamping existing phosphoric acid polymerization units.

Sweetn G®

Sweetn'G® is an intermediate process dedicated to Gasoline cut which can use else the SCPS-ready in fixed bed else the LCPS-30 diluted in the caustic depending on client requirements.

This process will selectively convert the acidic mercaptans to neutral disulfides in order to pass the copper strip, doctor test. Heavy sulfur molecules like thiophenes cannot be efficiently removed or transformed by caustic. As a consequence, light naphtha notably from FCCU and H-Oil® are usual feedstocks for a Sweetn'G® process. As a result, the unit scheme is adapted for each client and associated objectives such as meeting gasoline pool sulfur constraints.

Sweetn'G® combines the advantages of Sulfrex™ and Sweetn'K™ technologies thanks to optimized caustic management and without mandatory proprietary equipment. This results in a lower initial investment as well as low operating costs.

Prime-G+®

Prime-G+® stems from Axens' extensive experience acquired in cracked naphtha HDS and selective hydrogenation of LPG and gasoline. Although the naphtha splitter may be optional depending on the required HDS severity, the association of a Prime-G+® selective hydrogenation unit (SHU) with a splitter for light naphtha desulfurization and sweetening ideally complements the selective HDS on the heavier fraction.

Within the preferred arrangement, the "Prime-G+® 1st Step" produces an olefin-rich light cracked naphtha (LCN) and the sulfur-rich heavy cracked naphtha (HCN) is sent to the selective HDS to maximize octane retention.

Prime-G+® offer is particularly flexible allowing different process configurations to best fit the gasoline pool requirement and also maximize refinery profitability.

The first step of Prime G+® technology feature is in offering excellent preparation for the feed of the light gasoline etherification (TAME / TAEE) unit. The TAME/TAEE process ideally complements Prime-G+® technology in compensating for the octane loss and regaining the octane barrels.

PRU (Propylene Recovery Unit)

Axens Propylene Recovery Unit (PRU) processes LPGs that typically come from FCC or Coker units to produce a stream of high purity propylene suitable for petrochemical applications. Additional complex refinery or petrochemical purge streams containing propylene may also be treated.

The design is customized in order to fulfill the required propylene specifications, frequently chemical, chemical high purity or polymer grades or even custom specifications, with purities of up to 99.8 wt%.

Propylene impurities such as water, sulfur compounds, phosphine or arsine are removed through the use of specific Axens’ adsorbents (AxSorb® and AxTrap™), involving fully automated regeneration if necessary.

Sulfrex™

The extractive Sulfrex™ process eliminates mercaptans and reduces the total sulfur concentration. With its mild operating conditions of pressure and ambient temperature, this continuous process is ideal for C₃, C₄, LPG, light gasoline and NGL feeds.

Sulfrex™ covers several configurations:

• Olefinic LPG ex FCC, Coker and Visbreaking
• Non Olefinic LPG on saturated distillations columns, or from hydrotreating units
• Gas field NGL

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.