| 摘要 |
1,157,356. Hydrogenating aromatic hydrocarbons. AIR PRODUCTS & CHEMICALS Inc. 21 July, 1967 [21 July, 1966], No. 33568/67. Heading C5E. Aromatic hydrocarbons are catalytically hydrogenated to cycloaliphatic hydrocarbons in three zones, in the first of which the weight hourly space rate is 25-50 and 30-45% of the aromatic is hydrogenated, in the second of which the weight hourly space rate is 10-25 and 35-50% of the original aromatic is hydrogenated, and in the third of which the weight hourly space rate is 0.5-4 and substantially all the remaining aromatic is hydrogenated, the effluent from the first zone being cooled by admixture with recycled cycloaliphatic product before passage to the second zone, the effluent from the second zone being cooled (e.g. by indirect heat exchange) before passage to the third zone, and the effluent from the third zone being separated into vapour and liquid, at least part of the vapour being recycled to form part of the hydrogen for the first zone, and part of the liquid being recycled to cool the first zone effluent, the remainder of the liquid being collected as desired product. Suitable operating temperatures are: first zone 120-260‹ C.; second zone 135-260‹ C.; and third zone 135-232‹ C. The pressure in each zone may be 13À5-37À5 atmospheres. The catalyst, which may be the same or different in each zone, is conventional, e.g. Ni, Co, Pt, Pd, Rh, Fe or Ru supported on alumina, silica, pumice stone, asbestos, kieselguhr or diatomaceous earth. The hydrogenation of benzene to cyclohexane is described, but the following are also mentioned: toluene to methylcyclohexane, xylenes to dimethylcyclohexanes, and naphthalene to tetralin or decalin.
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