Selective conversion of 1,3,7-octatriene to aromatics

Abstract

Butadiene can be converted to aromatics in a two-step process. In the first step butadiene is dimerized by homogeneous palladium catalysts to 1,3,7-octatriene which in the second step is dehydrocyclized almost quantitatively to the aromatics o-xylene and ethylbenzene. With Co2(CO)8/AI203 the yield of 97% of C8 aromatics consisting of o-xylene (68%), ethylbenzene (27%), p-xylene (1 %) and m-xylene (1 %) could be obtained. Optimum reaction conditions were found at a temperature of 450 °C and a hydrogen pressure of 10 bar. After 20 h the catalyst lost activity and selectivity. Regeneration with air proved successful.

Butadiene

“…Dimerization results in the formation of 1,3,7-octatriene [1002-35-3] and 1,3,6-octatriene [25,26], which are, however, industrially uninteresting. The aromatic hydrocarbons xylene and ethylbenzene [27] can be made by the dehydrocyclization of 1,3,7-octatriene. If the dimerization is carried out under hydrogenation conditions, 1,7-octadiene and 1,6-octadiene are formed [28,29].…”