Styrene is converted to dimers under the action of zeolite ZSM 12 both in the presence and absence of the solvent (chlorobenzene). This transformation is characterized by a high conver sion of the monomer (up to 100 wt.%) and selective formation of linear isomers (70-75%). In the presence of zeolites ZVN and VKZ in chlorobenzene, styrene forms a mixture of oligomers (n = 2-7), among which the dimers prevailed, while without the solvent oligomers with an average molecular weight of ∼1510 are formed.Styrene dimers are promising as regulators of polymer chain growth, plasticizers of polymers and Plexiglas, a basis of synthetic lubricants, and components of epoxide, varnish and paint, and poly(vinyl chloride) materials. 1-4 Strong acids, namely, AcClO 4 , CF 3 SO 3 H, and p MeC 6 H 4 SO 3 H are usually used 5-7 for the synthesis of styrene dimers, although it is shown 8,9 that zeolites Y and Beta are highly active in styrene dimerization. The linear dimer of styrene, viz., (E) 1,3 diphenylbut 1 ene, was obtained with the selectivity up to 80% in the presence of zeolite Y at 70°C, whereas zeolite Beta is more selective (84-90%) with respect to the formation of cyclic styrene dimers: cis and trans 1 methyl 3 phenylindanes.The use of pentasils in styrene dimerization is unknown. Since these zeolites possess 10 stronger acid sites than zeo lites Y and Beta, it was of interest to study the catalytic properties of the pentasils in styrene dimerization.In the present work, we studied the transformations of styrene in the presence of pentasils of two different struc tural types: MTW (zeolite ZSM 12) and MFI (zeolites ZVN 11,12 and VKZ 13,14 ). The data obtained on the activity and selectivity of the catalysts in styrene dimerization were compared to their acidic properties and molecular sieve characteristics.
ExperimentalSamples of the pentasils in the H form were studied: industrial catalysts ZSM 12 (SiO 2 /Al 2 O 3 = 34) and ZVN (SiO 2 / * Dedicated to Academician A. I. Konovalov on his 75th birth day. Al 2 O 3 = 28) produced at the OAO ''Angarskii zavod katalizatorov i organicheskogo sinteza'' and VKZ (SiO 2 /Al 2 O 3 = 40) synthesized by the hydrothermal method from alkaline aluminosilicate gel using hexamethylenediamine as an organic additive.Before experiments on styrene oligomerization, the catalyst samples were heated in air for 4 h at 540°C. Styrene (OAO ''Salavatnefteorgsintez'') were distilled. Chlorobenzene was dehydrated using a standard method.Styrene oligomerization was carried out in a periodical isothermal reactor at 80-130°C in the presence of 5-40 wt.% catalyst in chlorobenzene and without a solvent. The initial styrene concentration in chlorobenzene [M] 0 was 2.2 mol L -1 . 1 H and 13 C NMR spectra were recorded on a Bruker AVANCE 400 spectrometer ( 1 H, 400.13 MHz; 13 C, 100.62 MHz) in CDCl 3 . High resolution mass spectra were measured on a Fisons Trio 1000 instrument, whose chromatograph was equipped with a DB 560 quartz column (50 m); the temperature of the column was increased from 50 to 320°C with a...
