Oligomerization Of 1-hexene Research Articles

Kinetics of 1-hexene dimerization catalyzed by a liquid-phase nickel complex

Reaction rates and activation energies for the oligomerization of 1-hexene catalyzed by a nickel complex of the formula Ni(F3COO)(C7H15COO) have been measured at temperatures varying between 0 and 20°C. Diethyl aluminium chloride was used as cocatalyst.

Oligomerization of 1‐hexene initiated by Zr(OnPr)4‐AlEt2Cl, 2. Mechanistic aspects

The mechanistic aspects of 1-hexene oligomerization, initiated by Zr(OnPr)4-AlEt2Cl at 20°C, are discussed on the basis of the product structures and distributions, the stability and reactivity of Mt-alkyls (Mt = metal) formed during 1-hexene oligomerization, the reaction behaviour of an internal olefin (cis-2-hexene) and the investigation of interactions between Zr (OnPr)4-AlEt2Cl. After comparing the different possible initation routes for 1-hexene oligomerization, a mechanism via insertion of 1-hexene into Al-alkyl bonds activated by zirconium is proposed. It was found that the olefin addition is not regiospecific. Primary addition into a linear alkyl-metal bond leads to an olefin insertion, whereas secondary addition only leads to elimination; when α- or β- branched alkyl-metal bonds are involved, only transfer to monomer takes place.

Oligomerization of 1-hexene with bimetallic catalysts based on titanium or zirconium derivatives and organoaluminum compounds

The oligomerization of 1-hexene at 20° C in the presence of various bimetallic systems obtained by reaction of titanium (IV) and zirconium (IV) derivatives with organoaluminum compounds has been studied. The transition metal, the nature of its substituents, and that of those attached to aluminum, strongly affect the catalytic activity. Oligomerization only proceeds with systems which contain Ti or Zr reduced forms. Two series of low molecular weight oligomers are formed, C6n and C6n+2. Each is composed of both saturated and unsaturated hydrocarbon homologues. The large amount of saturated products after hydrolysis shows that aluminum metal alkyls are either involved in the propagation or are very efficient transfer agents.

Synthesis of heterogeneous olefin-oligomerization catalysts using homogeneous nickel-chelate complexes as a basis

The synthesis and characterization of two nickel(II) catalyst precursors are described. The first is derived from cross-linking of the bis(glycidyl ether) of bis(1- p-hydroxyphenyl-1,3-butanedionato)nickel(II) with 1,2-diaminoethane and the second is obtained from polystyrene-supported chloro-2,4-pentanedithionatotriphenylphosphine-nickel(II). The compounds and their homogeneous precursors have been examined for their activity in catalysing the oligomerization of 1-hexene using triethylaluminium and ethylaluminiumdichloride as co-catalysts. Results obtained indicate that the polymeric complexes are active when AlEtCl 2 is used as a co-catalyst, but not when AlEt 3 is used. Furthermore, oligomerization is accompanied by isomerization, while a high selectivity for dimers is observed. Analysis of the complexes after catalytic runs reveals that some leaching of the nickel ions from the polymers has taken place.

Effect of silicon-to-aluminium ratio and synthesis time on high-pressure olefin oligomerization over ZSM-5

High-pressure oligomerization of propene, 1-butene and 1-hexene over ZSM-5 catalysts is described. Synthesis times were varied from 1 to 10 days and Si/Al reactant ratios between 20 and 500 were used. The average (on a number basis) crystal sizes of these samples ranged between 1 and 5 μm. The 1 day synthesis samples were tested for propene oligomerization at 300°C, 50 atm and a WHSV of 12±1 h −1. Under these conditions a Si/Al ratio of 18 had the longest lifetime. In terms of lifetime and catalyst utilization value, a sample of Si/Al=48, synthesised over 3 days, yielded the optimum performance of 60 h and 520 g liquid product/g catalyst, respectively, when run between 220 and 290°C. The number based crystal size distribution of this zeolite had its mean in the vicinity of 1 μm. ASTM distillation showed that about 65% of the product boiled in the diesel range. At 270°C, 1-butene was more reactive, and 1-hexene less reactive, than propene. For each feed the C 9C 12 fraction was predominant in the liquid product.

Cationic oligomerization of 1‐hexene catalyzed by EtAlCl2–chloroacetic acid complexes

AbstractLower oligomers (dimer to tetramer) of 1‐hexene were obtained in high yield (65 wt %) with a new cationic complex catalyst, EtAlCl2CCl3CO2H, in n‐hexane at 70°C, trimer being the major product. A strong oxo acid, CF3SO3H, yielded very similar products under the same conditions. Characteristics of the 1‐hexene oligomerization by these two catalysts were the high selectivity for dimers to tetramers and the absence of cracking of the product. In contrast, EtAlCl2 or AlCl3 alone led to oligomers with a higher molecular weight (∼103) and a broad molecular weight distribution, the structure of which was very complicated because of extensive cracking of products. A series of EtAlCl2chloroacetic acid (CClnH3–nCO2H, n = 0–3) complexes were also examined as catalysts. The yield of dimer to tetramer increased with increasing acidity of the chloroacetic acids. The mechanism of the 1‐hexene oligomerization with these complex catalysts was discussed on the basis of the structure of product oligomers.