Process Technologies

ISO-5

ISO-5™ is Axens technology for the isomerization of n-pentenes into isopentenes. It combines efficiently with Axens etherification technology to produce TAME.

As stringent regulations divert C5 olefins away from the gasoline pool, ISO-5™ offers an attractive scheme to solve RVP and olefins problems while at the same time producing valuable ethers. Axens first reference, the first of this kind in the world as well, started up in 2002.

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 is an alternative scheme 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™

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.

Isopure™

Axens Isopure™ technology is a solution to produce high purity isobutene from C₄’s olefins cuts.

This proven technology relies on a reactive distillation process in combination with hydro isomerization of 1-butene to 2-butenes. This concept eliminates the equilibrium limitations of conventional processes that convert 1-butene to 2-butene. The reactive distillation process occurs on a conventional distillation column combined with external reactors located on pump-around.-This facilitates the catalyst change-out operation and limits consequent unit downtime.

Butene-1 Superfractionation

Axens Butene-1 Superfractionation technology can be integrated within existing C4’s cut complexes or implemented in grassroot projects (combined or not with Axens Hydrogenation technology BD Lean and/or Axens MTBE technology).

This is a cost-efficient and industrially proven technology, based on a fractionation philosophy to isolate Butene-1 out of the others butenes co-boilers with high efficiency.

Depending on the project specificities, this technology can be featured with a Heat Pump system, providing long-term savings on utility and limiting environmental impact.

Total Hydrogenation (C₃, C₄, C₅ cuts)

Axens Total hydrogenation technologies answer the need for olefines bulk removal to produce a co-cracking recycle stream to specification.

A low residual olefins content in co-cracking stream is necessary to mitigate the negative effect of feed olefines in steam cracker furnaces.

Axens Total Hydrogenation technology typically includes a main reactor with an internal recycle. However, for more stringent needs, this technology might be configured with a finishing reactor to comply with very low olefins residual content, mainly when thriving to reach LPG product quality.

Axens total hydrogenation technologies can be configured to operate on alternative operating mode: total or selective. In addition, this technology can be revamped into selective hydrogenation, even after several year of operation, to support a product shift strategy.

2nd Stage Gasoline Hydrogenation Unit, GHU-2

In the second stage of pygas hydrogenation (GHU-2) the C₆-C₈ heart cut is further processed to prepare a feedstock suitable for aromatics recovery, by selectively hydrogenating the olefins and hydrodesulfurization.

This process consists in olefins and sulfur removal from all or a specific fraction of the first stage effluent. The complete removal of olefins and sulfur has to be ensured while minimizing aromatics hydrogenation. The effluent is then routed to an aromatics recovery unit.

1st Stage Gasoline Hydrogenation Unit, GHU-1

The first stage of the Gasoline Hydrogenation Unit (GHU-1) involves the selective hydrogenation of diolefins and styrenics. Efficiency of the conversion in this stage is essential for the downstream unit’s operation.

The first stage process aims to improve the stability of the raw pyrolysis gasoline by selectively hydrogenating the diolefins and alkenyl compounds, making it suitable for further processing in a second stage. The reaction is carried out mainly in the liquid phase, on a specific catalyst in a fixed bed reactor.

The operating conditions are selected to maximize the conversion of diolefins and alkenyl-aromatics, while minimizing the formation of heavy products by polymerization, preventing any aromatics loss.

In this stage, palladium or nickel-based catalysts are used depending on the site-specific constraints among which the feedstock characteristics, the product specifications, the unit characteristics and the operating conditions.