Catalytic oligomerization

The direct methane conversion technology, which has received the most research attention, involves the oxidative coupling of methane to produce higher hydrocarbons (qv) such as ethylene (qv). These olefinic products may be upgraded to Hquid fuels via catalytic oligomerization processes. 

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). 

Another source, catalytic oligomerization, which produces the alpha olefins using the Ziegler process mentioned above, has its own treatment in Chapter 21. But then the Oxo process really only replaces steps-three and four in Figure 15-3. Besides, Oxo higher alcohols still have branches. 

The application of perfluorous polyethers in biphasic catalysis was first described by Vogt (133), who also synthesized ligands based on hexafluor-opropene oxide oligomers to create metal complexes that are soluble in the perfluorous polyethers. The solvophobic properties of the fluorous solvent were successfully incorporated in the metal complexes catalytic oligomerization and polymerization reactions with nickel and cobalt complexes were demonstrated. 

Microwave heating was also used to induce catalytic oligomerization of methane to afford C2-C4 hydrocarbons.571 Changing the catalysts and the applied power and the use of diluent gas (He) allowed significant alteration of product selectivities. Selectivity to benzene over nickel powder or activated carbon was 24 and 33%, respectively. 

The second part deals with the complex chemistry and catalytic oligomerizations of allene. We emphasize the importance of the role played by auxiliary ligands of transition metals in determining the paths of catalytic oligomerizations. Recent reviews 11-12) covering most of the literature published up to 1972 lack a perspective view on catalysis. The most recent review 13) describes mainly oligomerization and cooligomerization. 

Torres, M., Lopez, L., Dominguez, J. M., Mantilla, A., Ferrat, G., Gutierrez, M. and Maubert, M. Olefins catalytic oligomerization on new composites of beta-zeolite films supported on a-Al203 membranes. Chem. Eng. J., 2003, 92, 1-6. 

Bhore, N. A. Catalytic oligomerization process using synthetic mesoporous crystalline material. US Patent 5134243, 1991. 

Davydov, A. A., Kantcheva, M. and Chepotko, M. L. FTIR spectroscopic study on nickel(II)-exchanged sulfated alumina nature of the active sites in the catalytic oligomerization of ethene. Catal. Lett., 2002, 83, 97-108. 

Espinoza, R. L., Snel, R., Korf, C. J. and Nicolaides, C. P. Catalytic oligomerization of ethene over nickel-exchanged amorphous silica-aluminas effect of the acid strength of the support. Appl. Catal., 1987, 29, 295-303. 

As an example, catalytic cracking of pme LDPE was carried out in the screw kiln reactor over mesoporous Al-MCM-41 (plastic/catalyst mass ratio of 50) at T1/T2 = 400/450°C, respectively. The reported yields of hydrocarbons within the gasoline range (C5-C12) amounts to 80% with a high content of C7-C8 hydrocarbons, stemming likely from the occurrence of secondary catalytic oligomerization reactions affecting to the initially formed C3 and C4 fractions. 

Bhore et al. 5260501 09.11.93 Catalytic Oligomerization Process Using Modified Mesoporous Crystalline Material... 

The catalytic oligomerization of olefins in the presence of OAC and the olefin polymerization in the presence of transition metals are based on similar olefin insertions into the metal-carbon and metal-hydrogen bonds (see Section 3.2). However, in organoaluminium compounds, the structure of the active center is defined more simply and more reliably. Data on its coordination state, thermodynamic and kinetic parameters have been reported (e.g. Table 13). 

Insertion reations of olefins into metal-carbon bonds are fundamental to catalytic oligomerization and polymerization (e.g., Ziegler-Natta systems). Furthermore, this reaction may provide a method for stereoselective formation of a carbon-carbon bond. 

R = Me, H) are catalytically oligomerized by (R3P)2PtCl2 complexes according to equation 45. Generation of an intermediate Pt=SiMe2 silylene as well as product... 

Finally, there are some works about progress in the development of adequate equipment design for solid catalytic oligomerization, e.g. reactive distillation. Since a solid catalytic system often implies frequent catalyst deactivation, it seems reasonable that the development of the catalytic system should be accompanied by a more convenient process and improved upgrading of oligomerization products. 

Biphasic catalysis is not a new concept for catalytic oligomerization chemistry. On the contrary, the oligomerization of ethylene was the first commercial example of a biphasic, transition metal catalyzed reaction. The process is known under the name Shell higher olefins process (SHOP) and the first patents originate from as early as the late sixties [234]. While the SHOP uses 1,4-butandiol as the catalyst phase. 

A plausible mechanism for this catalytic oligomerization is shown in Scheme 22.14. Chain growth occurs by olefin insertion, and chain termination occurs by 3-hydride elimination or chain transfer to monomer. These mechanisms parallel the mechanisms for olefin polymerization, but the relative rate for chain growth versus chain transfer is smaller than that for polymerization. These relative rates, and therefore tlie average chain length, are influenced by added ligands such as tertiary phosphines. 

The nickel(O) complexes are effective in cyclooligomerization of butadienes. The complexes XII and XIII have been demonstrated to be intermediates in the catalytic oligomerization of butadiene the ligand displacement reaction of XII gives a mixture of 1,2-divinylcyclobutane, 4-vinylcyclohexene, and 1,5-cyclooctadiene (Brenner et al., 1969 Heimbach and Wilke, 1969), whereas complex XIII affords 1,5,9-cyclododecatriene (Wilke, 1963 Bogdanovic et al., 1969). Similarly, a number of bis(it-cyclo-... 

Catalytic oligomerization also is called catalytic polymerization, catpoly, and catalytic condensation. The process converts C3 and C4 olefins into Ce to C9 olefins, which are excellent gasoline blend stocks. Per Table 22, the research octane numbers for Ce and Cs olefins such as methyl-2-pentenes and 2,2,4-trimethylpentenes are greater than 97. 

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