Ethylene, Shell higher olefins process SHOP

Shell Higher Olefins Process (SHOP). In the Shell ethylene oligomerization process (7), a nickel ligand catalyst is dissolved in a solvent such as 1,4-butanediol (Eig. 4). Ethylene is oligomerized on the catalyst to form a-olefins. Because a-olefins have low solubiUty in the solvent, they form a second Hquid phase. Once formed, olefins can have Htfle further reaction because most of them are no longer in contact with the catalyst. Three continuously stirred reactors operate at ca 120°C and ca 14 MPa (140 atm). Reactor conditions and catalyst addition rates allow Shell to vary the carbon distribution. 

Biphasic catalysis is not a new concept for oligomerization chemistry. On the contrary, the oligomerization of ethylene was the first commercialized example of a biphasic, catalytic reaction. The process is known under the name Shell Higher Olefins Process (SHOP) , and the first patents originate from as early as the late 1%0 s. 

In addition to the neutral nickel/phosphine complexes used in the Shell Higher Olefins Process (SHOP), cationic Ni-complexes such as [(mall)Ni(dppmo)][SbF6] (see Figure 5.2-7) have attracted some attention as highly selective and highly active catalysts for ethylene oligomerization to HAOs [106]. 

Apart from the UOP Pacol process, today s only other meaningful economic process is the Shell higher olefin process (SHOP) in which /z-olefins are produced by ethylene oligomerization. Until 1992 Hiils AG used its own technology to produce -60,000 t/year of /z-olefins by the chlorination of /z-paraffins (from Molex plant) and subsequent dehydrochlorination [13]. In the past, the wax cracking process (Shell, Chevron) played a certain role. In the Pacol and Hiils processes, olefins are obtained as diluted solutions in paraffin (Pacol to max. 20%, Hiils about 30%) without further processing these are then used for alkylation. In contrast, the SHOP process produces pure olefins. 

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... 

Oligomerization of ethylene to higher even carbon number alpha olefins. This is the growth part of the Shell Higher Olefin Process (SHOP) Unit. 

Probably the first example of a process employing the biphasic concept is the Shell process for ethylene oligomerization in which the nickel catalyst and the ethylene reactant are dissolved in 1,4-butanediol, while the product, a mixture of linear alpha olefins, is insoluble and separates as a second (upper) liquid phase (see Fig. 7.1). This is the first step in the Shell Higher Olefins Process (SHOP), the largest single feed application of homogeneous catalysis [7]. 

Dimerisation of olefins is a major industrial process, and is carried out on a multi million ton scale annually.111 One of the most important methods is represented by the Shell Higher Olefin Process (SHOP), which can even be run under biphasic conditions. In the oligomerisation of ethylene, the catalyst is generated in situ in 1,4-butanediol from a nickel salt, Na[BH4] and a chelating ligand. The olefins formed in the reaction are immiscible with the polar solvent and are isolated by phase separation and subsequent distillation.[2]... 

The chelate effect is important in the oxidative additions of P—C bonds which, in the case of nickel, give P—O and P—N chelate complexes of the type used as ethylene oligomerization catalysts in the Shell higher olefin process (SHOP),91 for example,... 

The solvent properties of alcohols with short carbon chains are similar to those of water and such alcohols could be used as the nonaqueous catalyst phase when the products are apolar in nature. The first commercial biphasic process, the Shell Higher Olefin Process (SHOP) developed by Keim et al. [4], is nonaqueous and uses butanediol as the catalyst phase and a nickel catalyst modified with a diol-soluble phosphine, R2PCH2COOH. While ethylene is highly soluble in butanediol, the higher olefins phase-separate from the catalyst phase (cf. Section 2.3.1.3). The dimerization of butadiene to 1,3,7-octatriene was studied using triphenylphosphine-modified palladium catalyst in acetonitrile/hexafluoro-2-phe-nyl-2-propanol solvent mixtures [5]. The reaction of butadiene with phthalic acid to give octyl phthalate can be catalyzed by a nonaqueous catalyst formed in-situ from Pd(acac)2 (acac, acetylacetonate) and P(0CeH40CH3)3 in dimethyl sulfoxide (DMSO). In both systems the products are extracted from the catalyst phase by isooctane, which is separated from the final products by distillation [5]. 

The reaction of the stabilized ylide benzoylmethylene-triphenylphosphorane with Ni(0) in the presence of triphenylphosphane leads to the oligomerization catalyst 2, which catalyzes the reaction of 6000 moles of ethylene per mole of complex at 50 bar and 50°C. The catalyst 2 is a model system for the Shell Higher Olefin Process (SHOP) for the production of liquid a-olefms of high linearity, which has been studied in detail by Keim and coworkers at the RWTH Aachen [9 c and literature, reviewed in 8]. 

Another area of investigation was based on nickel complexes anchored to cyclodextrins as an alternative to ethylene oligomerization catalysts for the Shell Higher Olefins Process (SHOP). The idea was that the cydodextrin cavity could lead to... 

The most important process worldwide is the Shell higher-olefin process (SHOP) in which ethylene is oligomerized to higher-molecular-mass, linear, a-ole-fins. The nickel-catalyst, containing a phosphorus/oxygen chelate ligand, is dissolved in the polar solvent 1,4-butanediol, which is not miscible with the a-olefins. Two big plant with a total capacity of 1 Mio. ty 1 are built in Geismar (USA) and Stanlow (UK). 

The nickel-catalyzed Shell higher olefin process (SHOP) is of major industrial importance [9,11]. Ethylene is converted to a-olefins with a statistical distribution in which the lower oligomers are favored (so-called Schulz Flory distribution). This is carried out at 80-120 °C and 70 140 bar in the presence of a nickel catalyst with phosphine ligands such as Ph2PCH2COOK. The product mixture is separated into C4 io, C12-18, and C20+ fractions by distillation. 

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]. 

The Shell Higher-Olefins Process (SHOP), which inclndes a commercial application of metathesis, was developed to convert ethylene into a range (Cio-Cig)... 

---