Oligomerization of 1-Pentene on Zeolite Catalysts

Catalysis in Industry - The oligomerization of 1-pentene is an efficient process for producing environmentally friendly high-quality fuel components. The catalytic properties of FAU, OFF, MOR, BEA,...     

Styrene oligomerization catalyzed by zeolites of different structural types

It was shown that styrene oligomerization in the presence of the zeolite ZSM-12 in a solvent (chlorobenzene) as well as without it proceeds with a high conversion (98–100 wt %) and a high selectivity for linear dimers (up to 82%). The main oligomerization products in the presence of the zeolite Beta are dimers (70–80%), mostly the linear isomer trans-1,3-diphenylbut-1-ene. In the presence of the less active zeolite Y, styrene gives a complex mixture of oligomers in which dimers (53–60%, in chlorobenzene) or dimers and trimers (60–80%, in bulk) are predominant.     

Oligomerization of 1-octene on micro-mesoporous zeolite catalysts

The oligomerization of 1-octene in the presence of micro- and micro-mesoporous catalysts based on zeolite Y (SiO₂/Al₂O₃ = 4.9) has been studied. The results of low-temperature nitrogen adsorption confirm the formation of mesopores with a diameter of 2–4 nm in the micro-mesoporous catalysts. An ammonia temperature-programmed desorption study of the acid properties of the synthesized zeolite catalysts has shown that the preparation of micro-mesoporous samples is accompanied by a decrease in the concentration and strength of acid sites. A comparison of the catalytic properties of the microporous and micro-mesoporous zeolites has revealed that the latter are the most active in 1-octene oligomerization and allow octene oligomers to be obtained with a selectivity of 65% at the 100% conversion of the monomer. The use of zeolite catalysts with the micro-mesoporous structure in the oligomerization of 1-octene affords oligomers with a broader molecular-mass distribution (degree of oligomerization n = 2–5) than on the microporous samples (n = 2 to 3).     

Oligomerization of α-octene catalyzed by zeolites

The oligomerization of octene-1 was studied in the presence of zeolites of different structural types (e.g., Y, Beta, ZSM-12, and ZSM-5). It was shown that at 150–200°C, wide-pore zeolite catalysts Y, Beta, and ZSM-12 exhibit high catalytic activity in the reaction. The conversion of catalyzed octene can be as high as 96%, and the yield of oligomers is 88–100 wt %. Zeolite ZSM-5 at 150–180°C has low activity and mainly catalyzes the isomerization of octene-1. As the temperature rises to 250°C, low molecular weight oligomers resulting from the cracking process are the main products of this reaction. The activity and selectivity of zeolite catalysts in the oligomerization of octene-1 are conditioned by their acidic properties and structural characteristics, as well as by the reaction conditions. It was revealed that the main oligomerization products are octene dimers having an alkylnaphthene structure and containing unsaturated hydrocarbons with tri- and tetra-substituted double bonds in amounts of 2.2–3.2%. The properties of the octene oligomers synthesized in the presence of zeolite Beta are similar to the characteristics of hydrogenated poly-α-olefins, the oligomerization of which was performed on AlCl₃ complexes.     

Dimerization of vinylarenes on zeolite catalysts

The main features of dimerization of vinylarenes, such as styrene, α-methylstyrene, β-methylstyrene, p-methylstyrene, p-methoxystyrene, p-methoxy-β-methylstyrene, m-chlorostyrene, and m-nitrostyrene used as an example, over zeolite catalysts were studied, and the high activity and selectivity of these catalysts in the reaction was shown. For styrene and α-methylstyrene, the vinylarenes having the largest production volume, catalysts that hold promise for industrial application were developed. Conditions for the selective linear dimerization (85–93%) and cyclodimerization (85–98%) of styrene and α-methylstyrene at a high conversion (100%) were determined.