Oligomerization of Butenes

Traditionally, solid acidic catalysts are applied in industry for the oligomerization of butenes and are still studied. MTS-type aluminosilicates,522 a NiCsNaY zeolite,523 and a silica-alumina containing 13% alumina524 proved to be active and selective catalysts. Moreover, deactivation rates of these catalysts are also favorable. Sulfated zirconia promoted with Fe and Mn was active and selective to yield primarily dimethylbutene isomers under supercritical conditions.525 A small amount of water improved productivity and decreased deactivation. A study showed that the blending octane number of Cg hydrocarbons is directly linked to the number of allylic hydrogens in the molecules.526... 

Oligomerization of butene over HMordenite has been carried out at 5 MPa and 523 K. The reaction gave mainly dimers and trimers with a minor fraction of tetramers and pentamers.[13] In contrast, oligomerization of butene over solid phosphoric acid catalyst gave mainly dimers. 

Chiche et a/.[56] have studied the oligomerization of butene over a series of zeolite (HBeta and HZSM-5), amorphous silica alumina and mesoporous MTS-type aluminosilicates with different pores. The authors found that MTS catalyst converts selectively butenes into a mixture of branched dimers at 423 K and 1.5-2 MPa. Under the same reaction conditions, acid zeolites and amorphous silica alumina are practically inactive due to rapid deactivation caused by the accumulation of hydrocarbon residue on the catalyst surface blocking pores and active sites. The catalytic behaviour observed for the MTS catalyst was attributed to the low density of sites on their surface along with the absence of diffusional limitations due to an open porosity. This would result in a low concentration of reactive species on the surface with short residence times, and favour deprotonation and desorption of the octyl cations, thus preventing secondary reaction of the olefinic products. 

Nkosi, B., Ng, F. T. T. and Rempel, G. L. The oligomerization of butenes with partially alkali exchanged NiNaY zeolite catalysts. Appl. Catal. A, 1997, 158, 225-241. 

Gomm et al. (45) made observations of coke deposition on zeolite catalysts using TEOM with GC analysis of the effluent gases. The mass change observed during conversion of 2-propanol to propene and diisopropyl ether at 273, 323, and 373 K was directly correlated with catalyst deactivation. Other examples involve oligomerization of -butenes on ferrierite catalysts (46) and interaction of isobutylene with various solid acids (47). 

Accordingly, we have investigated the performance of catalysts derived from the compounds (I) in the oligomerization of butenes at about ambient temperature and pressure and in the presence of other co-feeds. 

Zeolites - The zeolites, and in particular pentasil zeolite ZSM-5, have been intensively investigated in butene oligomerization for various purposes. The performance of this catalyst for alkene oligomerization was associated both with the catalyst synthesis, pre-treatment, and the reaction conditions. The product spectra were reported in the oligomerization of butene over mordenite and solid... 

It was described that nickel supported on H-mordenite was improved in stability and less regeneration was needed when the catalyst was used in oligomerization of butene. 

An industrial example of fast parallel reactions is the alkylation of isobutane with butenes to form isooctane, which is accompanied by the oligomerization of butenes to form C-8 and C-12 olefins, which have a lower octane rating. The reactions take place in a suspension of hydrocarbon droplets in sulfuric acid, and the octane number of the product increases with stirrer speed because of more rapid droplet coalescence and mixing of the hydrocarbons [2]. 

In the case of Ni-catalyzed oligomerization of butenes in acidic chloroaluminates, it has been shown that octene distribution (typically 39% dimethyUiexenes, 56% meffiyUieptenes, and 6% octenes) is independent of the addition of phosphine ligand. In addition 1-butene and 2-butene lead to the same product mixture due to very fast isomerization of 1-butene to the thermodynamic butene composition. 

E. Piera, C. Tellez, J. Coronas and M. Menendez. Use of zeolite membrane reactors for selectivity enhancement Application to the Uquid-phase oligomerization of /-butene. 

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