Catalytic activity of copper-containing cluster systems in the cyclodimerization of butadiene

The influence of the oxidation state of copper on the activity and selectiv ity of catalysts in the butadiene cyclodimerization reaction at a temperatu re of 473 K, a pressure of 0.1 MPa, a butadiene space velocity of 17 h(-1), and a residence time of 4 h in a fixed-bed flow reactor was studied. Coppe r in the Cu(O) and Cu(I) or Cu(II) state was introduced into supports (sili ca gel and ultrastable zeolite) by cryochemical synthesis and by impregnati on from Cu2Br2 or Cu(NO3)(2) solutions, respectively. The prevalent formati on of 4-vinylcyclohexene (4-VCH) and ethylbenzene (EB) with a 4-VCH/EB rati o of 1.8-58 and 0.001-0.16 was observed on the samples containing copper as Cu(I) or Cu(II) and on the catalysts prepared by deposition of Cu(O) from the solvent ethylbenzene tone of the desired products), respectively.