GB828879A - Upgrading light virgin naphtha - Google Patents

Abstract

A light virgin naphtha boiling in the range 0-200 DEG F. is upgraded by thermally-cracking 15-25 mol. per cent of the naphtha with 75-85 mol. per cent of steam at 1400-1500 DEG F. and 25-55 p.s.i.a. for a residence time such that a conversion of 55-70 weight per cent to dry gas is obtained, typically 0.1-1.0 second. Hydrocarbon partial pressures of 10-18 p.s.i.a. are preferred. In examples, an Arabian naphtha boiling in the range 65-160 DEG F. and having a research octane number of 65 was cracked at 1450 DEG F. with 80 mol. per cent steam and (a) a hydrocarbon partial pressure of 10.9 p.s.i.a. (total pressure 38 p.s.i.a.) for 0.36 second to give a conversion to dry gas of 58%, the liquid product (65-330 DEG F.) having a research octane number of 77.3 and a volatility (per cent overhead at 212 DEG F.) of 86.1; (b) a hydrocarbon partial pressure of 12.1 p.s.i.a. (total pressure 37 p.s.i.a.) for 0.39 second to give 63.8% conversion to gas and a liquid product of octane 78.1 and volatility 88.5; (c) a hydrocarbon partial pressure of 14.0 p.s.i.a. (total pressure 52 p.s.i.a.) for 0.34 second to give 68.5% conversion to gas and a liquid product of octane 86.3 and volatility 91.5.