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Tetramerisation Process Review Supplement Disclosure Number: IPCOM000179539D
Publication Date: 2009-Feb-17

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The Prior Art Database

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Tetramerisation Process Technology Review – Supplement 1


Denise Venter

Shailesh Maharaj

Kevin Blann

Craig McGregor

Johntho Dixon

Sasol Technology

Table of Contents

1      Introduction. 3

2      Catalyst Preparation. 3

3      Solvent Choice. 4

3.1       Solvent Preparation Section. 6

4      Activation of Catalyst in Presence of Ethylene. 9

5      Reactor Section. 11

5.1       Removal of Heat of Reaction. 12

5.2       Entrainment Mitigation. 12

5.3       Nozzles. 14

5.4       Reactor Mixing. 14

5.5       Surface Coatings. 16

5.6       Transfer Lines. 16

5.7       Hot Solvent Wash. 17

6      Primary Work-up Section. 18

6.1       Catalyst Deactivation. 18

6.2       Solids Separation. 19

6.3       Ethylene Recovery. 22

7      Conclusions. 23


1         Introduction

This document acts as a supplement to the Tetramerisation Process Technology Review published by R. Walsh and A Spamer on in 2006.[1]  The focus of this document is to expand on certain of the aspects mentioned in the original document.  These aspects relate to the process for selective oligomerisation of ethylene to form specific alpha olefins such as 1-butene, 1-hexene or 1-octene, but could also be applicable to the unselective oligomerisation of ethylene to produce a range of alpha olefins such as generated in Linear Alpha Olefin technologies, and the polymerisation or co-polymerisation of ethylene to polymers.   

As reported previously, an ethylene tetramerisation reaction that produces 1-octene in selectivities exceeding 70% has been demonstrated at Sasol Technology.   A variety of PNP and related diphosphine ligands in combination with Cr (III) compounds activated by aluminoxanes have been found to be very active and efficient catalysts for this purpose.[2]  Subsequently, a variety PNNP and related diphosphine ligands[3] with selectivity to 1-hexene plus 1-octene in ranges above 83% while still maintaining a 1-octene selectivity exceeding 40% have been developed and demonstrated.

The aspects discussed in this review will relate primarily to these catalyst systems, but should be applicable to related catalyst systems.


2         Catalyst Preparation

As reported previously, the typical selective oligomerisation catalyst requires a catalyst which consists of a transition metal; a ligand and optionally an activator or co-catalyst.  These catalyst components are discussed in depth by Walsh et al.  

Research at Sasol Technology has subsequently shown that, when the solvent used for the oligomerisation reaction is not a cyclic paraffinic solvent, there is a process benefit in using metal precursors such as Cr(ethylhexanoate)3 or Cr(naphthenate)3 that are available as solutions in mineral oil as opposed to solid precursors such as Cr(acetylacetono...