SYNTHESIS OF SYMMETRICAL ALKYL-AROMATICS BY USE OF SHAPE-SELECTIVE CATALYSTS

The concept of shape selectivity is available to produce symmetrical dinuclear aromatic hydrocarbons such as 2,6-dialkylnaphthalene and 4,4′-dialkylbiphenyl, which are the raw materials for liquid crystals and polyester with superior properties, respectively. The ZSM-5 catalyst exhibits high activity and selectivity for the formation of p-xylene in the disproportionation and alkylation of toluene. The catalytic activity of ZSM-5 for the conversion of naphthalene derivatives is markedly low due to its small pore size, although symmetrical dinuclear aromatic hydrocarbons are selectively formed. The high catalytic activity is obtained with twelve-membered ring zeolites. Among these zeolites, mordenite is the most selective catalyst to produce symmetrical dinuclear aromatic hydrocarbons. The precise controls of the size of pore opening and the acidic property are required to enhance the selectivity for symmetrical dinuclear aromatic hydrocarbons. The non-zeolitic molecular sieves also present a great opportunity in high selective synthesis of these compounds. © 1993 VSP.