Propene, oligomerization

Previous work of O Connor on high pressure oligomerization of propene over different zeolites, heterogeneous phosphoric acid, incorporated acids in clay, and nickel on different supports revealed that the major product in all cases was trimers. The catalyst systems referred to in the text may also be found in Table 2 (page 252). 

1 Zeolites - A number of zeolites with or without different modifications are reported in the literature as being active for alkene oligomerization. For example, in an earlier report, ion-exchanged zeolites of types X and Y were used for propene oligomerization. With the exception of NiX, which showed high selectivity to dimerizing, all other zeolites showed the same spectrum of products, namely saturated C2, C4, C5 and C7. The interpretation of the appearance of 

At present, ZSM-5 is known to be the most promising catalyst for the conversion of light olefins to higher molecular weight distillate fuels and/or gasoline, and is by far the most utilized zeolite since it is employed in the MOGD 

The ratio of intra-crystalline acid sites to external surface active sites in zeolites tends to increase with crystal size due to the geometric relation between volume and external surface area. Also, how varying the Si-Al ratio in the ZSM-5 catalyst affects crystal size in the oligomerization of propene has been investigated. The optimum Si-Al ratio was about 20, which yielded the best lifetime and activity. 

Certain basic materials have been used to deactivate surface acidity. By modifying the surface acidity of HZSM-5 with 4-methylquinoline or hexamethyl-disilazane more linear products have been obtained in propene oligomerization, and, by modifying the surface acidity of HZSM-5 with 2,6-di-/ r/-butylpyridine, 

---

Propene oligomerization leads to different products using the same catalyst but varying the reaction conditions. Thus, at moderate temperature and relatively high pressure the reaction conditions favour the formation of products with boiling point of at least 438 K. However, at elevated temperatures and moderate total pressure (from atmospheric to about 5.5 MPa) the gasoline range (C5-C10) is formed.[14]... 

Figure 3 Outline reaction scheme for propene oligomerization by Mi-based catalysts. For clarity only alkyl product structures are depicted.

J. J. W. Eshuis, Y. Y. Tan, A. Meetsma, and J. H. Teuben, Organometallics, 11, 362 (1992). Kinetic and Mechanistic Aspects of Propene Oligomerization with Ionic Organozirconium and -Hafnium Compounds Crystal Structures of [CpJMMe(THT)]"[BPh4] (M = Zr, Hf). 

The influence of various synthesis parameters on the morphology and crystal size of ZSM-5 and the relationship between morphology and crystal size and propene oligomerization activity. 

This paper presents results of an investigation into the effect which template type, sodium or potassium content, water content and aluminium source has on the crystal size and morphology of ZSM-5. The relationship between the crystal size and morphology, at similar Si/Al ratios, and performance for high pressure propene oligomerization is... 

Figure 2. Effect of particle/crystal size on catalyst utilization value in propene oligomerization over ZSM-5 (Temp. = 250 C Press. = 5MPa WHSV = 12h" )...

Watson et al. reported a leading example of (3-carbon elimination observed with a well-defined metal complex [67]. Thermal decomposition of a lutetium-isobutyl complex having a vacant coordination site leads to the formation of a lutetium-methyl complex and propene by way of (3-methyl elimination, the microscopic reverse of olefin insertion. A concerted four-center transition state is proposed. This study demonstrated that (3-carbon elimination is an energetically accessible process, and provided a model for the chain transfer that occurs during propene oligomerization. 

The coking during propene oligomerization over silica-supported heteropoly acid H3PW12O40 and its palladium-doped form and subsequent catalyst regeneration have been studied using and P MAS NMR. " ... 

Product distribution (C5-Cg hydrocarbons C%) from propene oligomerization. 

Other biphasic C—C bonding reactions were carried out with fluorous solvents, for instance Suzuki- and Sonogashira-couplings [124] or ethene or propene oligomerizations [125, 126], Further new solvent systems use ionic liquids for the linear dimerisation of 1-butene to octenes [127] or the hydrovinylation of styrene with a combination ionic liquid/supercritical carbon dioxide [128] (cf. Section 7.4). 

HZSM5 zeolites catalyze the transformation of propane aromatic products. This aromatization requires various steps of propene, oligomerization of propene, cyclization of oligomers and hydrogen transfer from naphtenes to olefinic compounds with formation of aromatics. The cracking of Cg-Cg oligomers leads to C2-C5 olefins which, like propene, participate in the formation of aromatics. 

Syntheses of iabeiled cumenes were carried out by benzene aikyiation with propene in the adsorbed phase over H-ZSM-11. To avoid propene oligomerization, benzene was aiways adsorbed first. To synthesize cumene iabeiled with isotope in the a-position of the aikyl chain (cumene 1), non-labelled benzene and propene 2- 3C were used. Cumene - labelled in the p-positions of the alkyl chain (cumene 2) was synthesized from non-labelled benzene and propene l- C. Cumene with 13C isotopes in p- positions of the alkyl chain and in the aromatic ring (cumene 3) was synthesized from all-ring labelled benzene (5% and a mixture of unlabelled propene and propene l- C (1 1). 

TPD-TGA experiments on ethylene and propene oligomerization on HZSM-5 gave similar weight increases, and product distribution for both feeds was also... 

---