Butene oligomerization

Heterogenized catalysts have also been tested in this reaction. Calcined nickel salts supported on aluminum and activated with (sec-BuOljAl or an AICI3 + Et2AlCl mixture oligomerized butenes to Cg-Cn olefins [622,623,844],... 

Butene. Commercial production of 1-butene, as well as the manufacture of other linear a-olefins with even carbon atom numbers, is based on the ethylene oligomerization reaction. The reaction can be catalyzed by triethyl aluminum at 180—280°C and 15—30 MPa ( 150 300 atm) pressure (6) or by nickel-based catalysts at 80—120°C and 7—15 MPa pressure (7—9). Another commercially developed method includes ethylene dimerization with the Ziegler dimerization catalysts, (OR) —AIR, where R represents small alkyl groups (10). In addition, several processes are used to manufacture 1-butene from mixed butylene streams in refineries (11) (see BuTYLENEs). 

Other Higher Oleiins. Linear a-olefins, such as 1-hexene and 1-octene, are produced by catalytic oligomerization of ethylene with triethyl aluminum (6) or with nickel-based catalysts (7—9) (see Olefins, higher). Olefins with branched alkyl groups are usually produced by catalytic dehydration of corresponding alcohols. For example, 3-methyl-1-butene is produced from isoamyl alcohol using base-treated alumina (15). 

Oligomerization of Ethylene. 1-Butene is a small by-product in the production of linear alpha-olefins by oligomerisation of ethylene. Linear alpha-olefins have one double bond at the terminal position and comprise the homologous series of compounds with carbon atoms between 4 and 19. The primary use of alpha-olefins is in the detergent industry. About 245,000 t/yr of 1-butene was produced for chemical use in the Gulf Coast of the United States in 1988 (72). 

In the biphasic batch reaction the best reaction conditions were found for the system [EMIM][(CF3S02)2N]/compressed CO2. It was found that increasing the partial pressure of ethylene and decreasing the temperature helped to suppress the concurrent side reactions (isomerization and oligomerization), 58 % conversion of styrene (styrene/Ni = 1000/1) being achieved after 1 h under 40 bar of ethylene at 0 °C with 3-phenyl-1-butene being detected as the only product and with a 71 % ee of the R isomer. 

Ionic liquid-catalyzed polymerization of butene is not limited to the use of pure alkene feedstocks, which can be relatively expensive. More usefully, the technology can be applied to mixtures of butenes, such as the low-value hydrocarbon feedstocks raffinate I and raffinate II. The raffinate feedstocks are principally C4 hydrocarbon mixtures rich in butenes. When these feedstocks are polymerized in the presence of acidic chloroaluminate(III) ionic liquids, polymeric/oligomeric products with... 

The addition of one olefin molecule to a second and to a third, etc. to form a dimer, a trimer, etc. is termed oligomerization. The reaction is normally acid-catalyzed. When propene or butenes are used, the formed... 

Figure 9-4. The Octol Oligomerization process for producing Os s and Ci2 s and Cis s olefins from n-butenes (1) multitubular reactor, (2) debutanizer column, (3) fractionation tower.

The 7r-back donation stabilizes the alkene-metal 7c-bonding and therefore this is the reason why alkene complexes of the low-valent early transition metals so far isolated did not catalyze any polymerization. Some of them catalyze the oligomerization of olefins via metallocyclic mechanism [25,30,37-39]. For example, a zirconium-alkyl complex, CpZrn(CH2CH3)(7/4-butadiene)(dmpe) (dmpe = l,2-bis(dimethylphosphino)ethane) (24), catalyzed the selective dimerization of ethylene to 1-butene (Scheme I) [37, 38]. 

In favorable cases for some single olefmic species, thermodynamic equilibria with respect to double-bond position can be attained at low temperatures without significant oligomerization. For example, ris-2-bu-tene has been isomerized with the P(CH3)3-modified catalyst at -20°C to give the thermodynamic equilibrium mixture having the composition 78.8% trarts-2-butene, 19.5% m-2-butene, and 1.7% 1-butene. The isomerization of 4-methyl-1-pentene (or of 2-methyl-1-pentene) in the presence of the same catalyst at 0°C also leads to the thermodynamic equilibrium mixture with the composition shown in Table II. If the reaction is carried out at low temperature, the individual isomerization steps can be followed At -58°C, isomerization to ci i-4-methyl-2-pentene occurs and is followed by isomerization to the trans isomer this is then con-... 

In the codimerization reaction, both reactants are present in large excess compared to the catalyst concentration. The selectivity toward a 1 1 codimerization to form 1,4-hexadiene, instead of a random oligomerization, represents a rather unique reaction, especially in view of the fact that the same catalyst also dimerizes ethylene to butene (3) at about the same rate as the codimerization. The explanation forwarded by Cramer (4, 7) is based on the overwhelmingly favored stability of the tt-... 

Table I gives the compositions of alkylates produced with various acidic catalysts. The product distribution is similar for a variety of acidic catalysts, both solid and liquid, and over a wide range of process conditions. Typically, alkylate is a mixture of methyl-branched alkanes with a high content of isooctanes. Almost all the compounds have tertiary carbon atoms only very few have quaternary carbon atoms or are non-branched. Alkylate contains not only the primary products, trimethylpentanes, but also dimethylhexanes, sometimes methylheptanes, and a considerable amount of isopentane, isohexanes, isoheptanes and hydrocarbons with nine or more carbon atoms. The complexity of the product illustrates that no simple and straightforward single-step mechanism is operative rather, the reaction involves a set of parallel and consecutive reaction steps, with the importance of the individual steps differing markedly from one catalyst to another. To arrive at this complex product distribution from two simple molecules such as isobutane and butene, reaction steps such as isomerization, oligomerization, (3-scission, and hydride transfer have to be involved.

A more recent raw material for plasticizer alcohols is crack-C4 as a byproduct of steamcrackers in ethene/propene production. After extraction of butadiene for use and etherification of isobutene with methanol to methyl-tertiary-butylether MTBE as an octane enhancer, a stream is left containing 1-butene, 2-butene, and butanes, so-called raffinate II. Oligomerization of the butenes yields C8 olefin mixtures ( dibutene ) as the main product and the corresponding C12 olefins as the main byproduct (tributene). They are the... 

The oligomerization of propylene and butenes to gasoline range olefins is a technology which began in the 1930s with the work of Ipatieff on phosphoric acid in... 

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