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SEPARATION OF ALPHA-OLEFINS FROM A LIQUID HYDROCARBON STREAM

IP.com Disclosure Number: IPCOM000012478D
Publication Date: 2003-May-09
Document File: 9 page(s) / 38K

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Abstract

This invention provides a reactive extractive distillation process for the recovery of 1-hexene using silver nitrate in ethylene glycol as reactive separation solvent

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SEPARATION OF ALPHA-OLEFINS FROM A LIQUID HYDROCARBON STREAM

 

1.      Andre Banier de Haan;2. Norbetus Josef Maria Kuipers and 3. Annebart Engbert Wentink

1.� 23 Chopinstraat, Losser, Netherlands;

2.� Tijenesch 1, 7491 GS, Delden, Netherlands;

3.� 40 Maanstraat, Enschende, Netherlands.        � � � � �

Abstract

This invention provides a reactive extractive distillation process for the recovery of 1-hexene using silver nitrate in ethylene glycol as reactive separation solvent.

BACKGROUND OF THE INVENTION

THIS invention relates to the separation of alpha-olefins from a liquid hydrocarbon stream.

The reaction of synthesis gas in a Fischer-Tropsch reactor at elevated temperature and pressure over a Fe or Co catalyst produces a range of hydrocarbons including paraffins, olefins and alcohols, with carbon chain length varying from 1 to greater than 100.� These hydrocarbons are then separated into different products which may then be used in the fuel and chemical industries.�

It is known in the art that the separation of olefins from hydrocarbon streams such as those produced from a Fischer-Tropsch reaction is particularly difficult.� Prior art processes for the extraction of alpha-olefins from hydrocarbon streams derived from Fischer-Tropsch processes involve a distillation step to remove a required cut of hydrocarbons, oxygenates are removed from the cut whereafter it is subjected to etherification followed by superfractionation.� A typical process is described in South African patent no. 98/4676.� Such processes are costly and often do not result in a high purity product.

It is an object of this invention to provide an alternative and improved method for the separation of alpha-olefins from a liquid hydrocarbon stream.

SUMMARY OF THE INVENTION

According to the invention there is provided a method for the removal of alpha-olefins from a liquid hydrocarbon stream including the steps of:

contacting the hydrocarbon stream with a polar solvent containing transition metal ions which selectively form a complex with the alpha-olefins in the hydrocarbon stream;

removing the complexed alpha-olefins, together with the polar solvent, as a bottoms product in a reactive extractive distillation column; and

decomplexing the alpha-olefins from the transition metal ions and removing the alpha-olefin from the polar solvent to obtain an alpha-olefin product.

Advantageously, the polar solvent includes a suitable ligand complexed to the transition metal ion in the solvent.

The polar solvent may be an organic polar liquid.� Typical organic polar liquids include N-methyl-2-pyrrolidone, N-methyl-morpholine, salfolane, alcohols such as ethylene glycol and propylene glycol, or mixtures thereof.� The preferred organic polar liquid is ethylene glycol.

The solvent may be an inorganic polar liquid such as water, or a mixture of polar organic and inorganic liquids, such as a mixture of water and ethylene glycol.

Typical ligands include organic phosphonic acids, organic sulphuric acids and c...