| 摘要 |
Waxy distillates are cracked to obtain C8-C18 olefins by using as the quenching medium for the effluent from a naphtha steam cracking process. The naphtha, boiling in the range 100-300 DEG F., is cracked conventionally by mixing with 0.2-0.5 wt. of steam per wt. of naphtha and cracking at 0-50 p.s.i.g. and 1300-1500 DEG F. for 0.1-5 seconds to obtain over 40% wt. conversion to C3-. The waxy distillate should contain less than 50% wt. cyclic compounds and boil in the range 500-1200 DEG F., e.g. eicosane, gas oils obtained from Lirik, Bahia, San Joaquin, Tia Juana, or Middle East crudes, a raffinate from phenol extraction of a cycle oil or a petrolatum. The oil is heated to 400-800 DEG F. and introduced in amounts of 30-70% wt. of the total effluent from the cracker to reduce the temperature of the effluent to below 1000 DEG F. in 0.2-2 seconds. The waxy distillate may be introduced at one or several points. The product is distilled to separate C2-C5 olefins and diolefins, cracked naphtha (e.g. 300 DEG F. end point), C8-C18 straight-chain olefins as required and an oil of reduced pour point compared with the waxy distillate. The C8-C18 olefins may be purified by steam stripping, distillation, extraction and/or selective hydrogenation.
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