| 摘要 |
<p>1488571 Styrene MONSANTO CO 2 Jan 1975 [2 Jan 1974] 50/75 Heading C5E Styrene is prepared by (a) dehydrocoupling toluene in the vapour phase in the presence of a solid metal oxide at 500-650‹ C., (b) separating the dehydrocoupling effluent by distillation to provide a stilbene fraction, (c) treating the stilbene fraction to remove organic and inorganic polar impurities, (d) reacting the purified stilbene fraction in the vapour phase with ethylene in the presence of a disproportionation catalyst at 350-500‹ C. and (e) recovering styrene from the disproportionation reaction. The stilbene fraction may be purified by passing it through a bed of adsorbent material, such as alumina or diatomaceous earth; by contact with an alkali metal or an organometallic compound of a Group Ia, IIa or IIIa metal; or by distillation and crystallization. The dehydrocoupling effluent may be separated to give an unreacted toluene fraction, a cis-stilbene and bibenzyl fraction and a trans-stilbene fraction, the first two fractions being recycled to the dehydrocoupling reaction. The dehydrocoupling catalyst may comprise an oxide of Pb, Cd, or Bi on a support such as SiO 2 , Al 2 O 3 , SiO 2 -Al 2 O 3 or MgAl 2 O 4 spinel. The disproportionation catalyst may comprise oxides of Mo, W, V, Nb, Ta or Re, or hexacarbonyl compounds and sulphides of W and Mo on a support, e.g. SiO 2 or Al 2 O 3 .</p> |
