Shell -Higher-Olefins-Process

Stoichiometric reaction of the type shown by 7.4 also leads to the formation of ethylene oligomers. In the Ethyl Corporation process one step involves stoichiometric reaction of this type. Another variant of this is the Conco process, where such stoichiometric reactions are followed by oxidation and hydrolysis of the aluminum alkyls. This gives linear a-alcohols that are used in biodegradable detergents. The co-product is highly pure alumina, which has a variety of uses, including that of an acidic heterogeneous catalyst. 

As already mentioned, the mechanism of oligomerization is the same as discussed for polymerization, and a catalytic cycle similar to the one shown in Fig. 6.3 operates. Many nickel-phosphine complexes have been successfully used as the precatalysts 7.17 is one such example. As shown by 7.5, reaction of a phosphorous ylide with a suitable nickel-containing precursor makes this 

Isomerization. Hydrolbrmylation, Hydrogenation. Soluble cobalt catalyst 

Under the reaction conditions the precursor complex probably generates a nickel-hydride species, which then initiates the oligomerization reaction. Evidence for this comes from the studies on the reactions of 7.17. As shown by 7.6, on reaction with ethylene 7.17 eliminates styrene and produces a nickel-hydride complex. A model catalytic intermediate 7.18 has been characterized by single-crystal X-ray studies. Complex 7.18 reacts with ethylene to give a nickel-ethyl species in a reversible manner. This is shown by reaction 7.7. Reactions 7.6 and 7.7 are strong evidence for the involvement of a nickel-hydride catalytic intermediate. 

OTHER ALKENE-BASED HOMOGENEOUS CATALYTIC REACTIONS 

SHOP involves essentially three sequential operations. First, ethylene is oligomerized with a soluble nickel catalyst to give linear a-alkenes. Second, over a heterogeneous catalyst these are isomerized to internal alkenes. Third, the internal alkenes of four to eight carbon atoms are mixed with 20 or more carbon-containing internal alkenes. The mixture is then subjected to metathesis reaction (see Section 7.3). This produces internal alkenes of about 12-18 carbons. 

For the syntheses of long-chain alcohols, the C,2,3 alkenes are isomerized, hydromylated, and hydrogenated. All the three reactions are catalyzed by Co-based homogeneous hydroformylation catalysts in combination with a ligand such as tributyl phosphine. These reactions are, however, not part of SHOP. 

Synthesis of long-chain alcohols from a-alkenes C-o alcohol 

Many nickel-phosphine complexes have been successfully used as precatalysts, and 6.46 is one early example. As shown by reaction 6.8.1.1, reaction between NiCCOD), a Wittig reagent (a phosphonium ylide), and PPhj gives 6.46. This is an oxidative addition reaction because as shown hy the formal arrow pushing mechanism (reaction 6.8.1.2) zero-valent nickel is converted to a Ni complex. 

Note that the arrow pushing mechanism takes into account that, while formally the Ni-Ph and Ni-0 bonds are covalent bonds, the Ni-P bond is a dative bond. Chelating ligands having the backbone of the type present in 6.46 are often referred to as (P, O) ligands. 

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Shell Higher Olefin Process) plant (16,17). C -C alcohols are also produced by this process. Ethylene is first oligomerized to linear, even carbon—number alpha olefins using a nickel complex catalyst. After separation of portions of the a-olefins for sale, others, particularly C g and higher, are catalyticaHy isomerized to internal olefins, which are then disproportionated over a catalyst to a broad mixture of linear internal olefins. The desired fraction is... 

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. 

The 0x0 process is employed to produce higher alcohols from linear and branched higher olefins. Using a catalyst that is highly selective for hydroformylation of linear olefins at the terminal carbon atom. Shell converts olefins from the Shell higher olefin process (SHOP) to alcohols. This results in a product that is up to 75—85% linear when a linear feedstock is employed. Other 0x0 processes, such as those employed by ICI, Exxon, and BASE (all in Europe), produce oxo-alcohols from a-olefin feedstocks such alcohols have a linearity of about 60%. Enichem, on the other hand, produces... 

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]. 

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

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... 

SHOP [Shell Higher Olefins Process] A process for producing a-olefins by oligomerizing ethylene, using a proprietary rhodium/phosphine catalyst. The a-olefins can then be iso-merized to internal olefins as required. Invented by W. Keim in the Institut fur Technische Chemie und Petrolchemie, Aachen, in the 1970s. The first plant was built in Geismar, LA, in 1979 the second in Stanlow, Cheshire, in 1982. Licensed worldwide by a consortium of Union Carbide, Davy-McKee, and Johnson Matthey. 

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)... 

Shell entrained flow gasifier, 6 799-800 Shellfish poison, 5 822 Shell higher olefins process (SHOP), 17 122, 718-720, 725, 26 939... 

Shell higher olefin process (organic/organic) and the Ruhrchemie-Rhone Poulenc propene hydroformylation process (aqueous/organic). The diversity of the applications may confuse the newcomer but it is not easy to comprehend even by the more experienced. A guide to this field may help a lot, and this is why the book of Adams, Dyson and Tavener is most welcome. 

A very elegant solution to solve this problem is the introduction of either a permanent or a temporary phase boundary between the molecular catalyst and the product phase. The basic principle of multiphase catalysis has already found implementation on an industrial scale in the Shell higher olefin process (SHOP) and the Ruhrchemie/Rhdne-Poulenc propene hydroformylation process. Over the years, the idea of phase-separable catalysis has inspired many chemists to design new families of ligands and to develop new separation... 

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. 

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