Manufacturing processes Shell Higher Olefin Process

Shell manufactures a-olefins from ethylene by oligomerization with a nickel catalyst in a polar solvent such as ethylene glycol, under the conditions specified in Equation 27. This corresponds to the first part of the SHOP process (Shell Higher Olefin Process) described in Section 6.2.2. The world production is estimated to be over 1 Mt/a. 

Catalysts based on nickel that dimerize or oligomerize a-olefins have been known for many years and are commercially valuable. The Shell higher olefin process (SHOP), for example, uses Ni(II) catalysts developed by Keim and coworkers such as 1.1 and 1.2 bearing P-O chelating ligands to oligomerize ethylene into higher olefins in the manufacture of surfactants, lubricants, and fine chemicals (Fig. 1) [9-11]. Late transition metals are more suited for the polymerization of... 

Another approach is to separate the products from the homogeneous catalyst using a two phase liquid system. For example, this method is used in the oligomerization step of the Shell Higher Olefins Process for the manufacture of linear a-olefins.5,9-11,330 A polar nickel catalyst containing a P- chelate ligand is dissolved in a polar solvent e.g. 1,4-butanediol, which is immiscible with higher oc-olefins, and recovery of the catalyst is easily achieved by simple phase separation. 

The i-oleftns obtained have a purity of more than 95 molar per cent of terminal olefins and are devoid of branched structures or diolefinic or cyclic impurities. These z-olefms, which all have an even number of carbon atoms, are produced with yields that vary according to a statistical distribution, with a maximum of C, 0-C, 2-Cj, for example, if the final product is intended for the manufacture of linear alkylbenzene. Due to the low yield of a given cut, it is understandable that the upgrading of all the other fractions is economically necessary. Since the upgrading of the light and heavy fractions is often a problem. Shell in the United States has developed the SHOP (Shell Higher Olefin Process), in which these effluents are converted to a cut for detergents by isomerization and metathesis. 

It is still unclear how the initiation step in alkene metathesis occurs and how the initial carbene forms. Commercial applications of metathesis include the triolefin process, in which propylene is converted to ethylene and butene, the neohexene process, in which the dimer of isobutylene, Me3CCH=CMe2, is metathesized with ethylene to give Me3CCH=CH2, an intermediate in the manufacture of synthetic musk, and a 1,5-hexadiene synthesis from 1,5-cy-clooctadiene and ethylene. Two other applications, SHOP and ROMP (Shell higher olefins process and ring-opening metathesis polymerization), are discussed in the next section. 

Pentene can be obtained by co-dimerization of ethylene with propene [41]. 1-Hexene is manufactured by SHOP (shell higher olefins process) [42] or via trimerization of ethylene [11,43] and, on a much smaller scale, by dehydration of corresponding alcohols [44]. 

The required terminal olefins used as substrates for the hydroformylation, such as 1-pentene or 1-octene, are available in large scales and can be derived either from Sasol s Fischer-Tropsch process or from the shell higher olefins process (SHOP), respectively [43, 44]. Alternatively, trimerization or tetramerization of ethylene affords 1-hexene [45] or 1-octene [46]. Dimerization of butadiene in methanol in the presence of a Pd catalyst (telomerization) is another industrially used access for the manufacture of 1-octene [46]. 1-Octene can also be produced on a large scale from 1-heptene via hydroformylation, subsequent hydrogenation, and dehydration (Scheme 6.2) [44]. This three-step homologation route is also valuable for the production of those higher olefins that bear an odd number of C atoms. (X-Olefins can also be derived from internal olefins by cross-metathesis reaction with ethylene [47]. 

In the following section, we discuss the industrial process for the manufacture of a-olefins utilizing nickel complexes as catalysts. This process is known as Shell higher olefin process or SHOP. The mechanism of oligomerization by the Ni-based catalyst is basically the same as that discussed in Section 6.3. However, in this case the ligand environment around the nickel is such that the chain length remains low, but not too low. 

Broadly speaking, metathesis covers a class of reactions where an interchange of carbon atoms between pairs of double bonds takes place. We have already seen application of metathesis (see Section 6.8.1) in Shell higher olefin process (SHOP). It is also used for the manufacture of the specialty polymer Vestenamer from cyclooctene (see reaction 7.2.3). As shown by reactions 7.3.1 and 7.3.2, in both these cases the highlighted carbon atoms are exchanged between the pair of double bonds. 

FIG. 3 Flow sheet of the manufacture of n-u-olefins and /z-y-olefins by the Shell higher olefin process (SHOP)... 

Sheet production, of methacrylic ester polymers, 16 282 Sheet silicon, 23 40—41 Shell a-olefin manufacture, 17 713—714. See also Shell higher olefins process (SHOP)... 

Production of more than 3 million tonnes of n-butanal demonstrates the strength of the aqueous-phase oxo concept, as do some other applications of two-phase homogeneous catalyst systems such as Shell s SHOP process (two-phase but not aqueous cf. Section 7.1) or variations by Rhone-Poulenc [11], Montedison [12], Kuraray ([13] and Section 6.9), or Hoechst [14] manufacturing higher olefins, vitamin precursors, telomers, or fine chemicals. 

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