OXIDATIVE DEHYDROGENATION OF ETHYLBENZENE WITH CARBON-DIOXIDE

An attempt to use carbon dioxide as a diluent and oxidant in the dehyd rogenation of ethlybenzene to styrene was carried out over an activate d carbon-supported iron catalyst (Fe 17 wt.-%) at 773-973 K, CO2/ethyl benzene = 50-70 mol/mol and W/F = 30-120 g h/mol. An addition of 20-30 mol-% lithium nitrate to iron resulted in a significant increase in t he catalytic activity. The highest yield of styrene (40-45%) with more than 90% selectivity was obtained at a ratio of lithium to iron of 0. 1-0.2 (mol/mol). In addition to styrene, carbon monoxide and water wer e formed as products. This indicated that the reaction proceeds via an oxidative dehydrogenation mechanism. Added lithium nitrate was conver ted into lithium ferrite during the treatment of an iron-lithium co-lo aded activated carbon catalyst under carbon dioxide at 973 K. Lithium ferrite thus formed would be an active center of the reaction.