Cyclodimerization of butadiene in the presence of copper-containing zeolite catalysts

A study has been made of the cyclodimerization of butadiene (85-190 degrees C, pressure 0.1 MPa, amount of catalyst 17 cm(3), time of reaction cycle 4.5-7.5 hr, butadiene feed rate 15-17 hr(-1)) in a flow-type reactor with a stationary catalyst bed in the presence of copper-containing bead catalyst Cu-TSEOKAR-10 and original ultrastable zeolite catalysts. It has been shown that, under certain conditions in the presence of Cu-TSEOKAR-10, within 30-32 hr of its operation, including the stages of activation (200 degrees C, N-2, time 2-3 hr) and reaction (140 degrees C, butadiene feed rate 17 hr(-1), duration of one stage 4.5-7.5 hr), selective conversion of butadiene to target reaction products (4-vinylcyclohexene-1-ethylbenzene) can take place with a selectivity of 70-75 wt.% and a butadiene conversion of 10-12 wt.%. It was established that the dealuminizing of an ultrastable Y zeolite promotes an increase in the Si/Al modulus and in the activity of the catalyst. It is shown that, at 190 degrees C with a pressure of 0.1 MPa and a butadiene feed rate of 17 hr(-1), within 4-6 hr the selectivity with respect to the main reaction products amounts to 77-89 wt.%, with a butadiene conversion of 60-90 wt.%. A suggestion is made concerning the cause of the change in the ratio of target products during the reaction and the main factors affecting the activity of the catalysts studied and the selectivity of their action. (C) 1997 Elsevier Science Ltd. All rights reserved.