GB492567A - Process for the conversion of butanes into gasoline boiling range liquids - Google Patents

Abstract

<PICT:0492567/IV/1> To convert butanes into gasoline boiling range liquids of high antiknock value, they are heated, e.g. to 540-615 DEG C. under pressure, e.g. 20-70 atmospheres, to produce substantial amounts of butenes and propene, the products of the pyrolytic conversion are fractionated into fixed gases, paraffins and olefines of 3-4 C atoms molecule, and liquids of gasoline boiling range, and the intermediate fraction is polymerized by contact with solid phosphoric acid catalysts preferably at 205-288 DEG C. and 10-70 atmospheres pressure, the products of polymerization being fractionated into hydrocarbons of less than 4 carbon atoms/molecule, a butane fraction which is recycled, and liquid gasoline boiling range polymers constituting the principal product. Butanes from the stabilization of gasoline, or from the polymerization of butane-butene mixtures from cracked gasoline are fed at 1 into tank 3. Recycled butane may be fed in at 119. The supplies may be augmented by introducing butane containing gases from other sources into the process at suitable points. The liquid contents of tank 3 are pumped to a tubular heater 9 and cracked to produce olefines. The products are cooled and partially condensed in air and water condensers 13, 14. A heat exchanger may be substituted for air condenser 13. The cooled products augmented if desired with olefine containing gases from other cracking operations, pass to column 25 conditions in which are adjusted so that gases lighter than propene are drawn off at the top. The remaining liquid passes from the bottom to column 31, from the top of which propane, propene, butanes and butenes are driven off, part to be condensed at 37 and returned to column 31 as refluxing liquid, and the remainder augmented if desired with propane-butane fractions from outside sources, and containing propene and butenes, to the polymerization treatment. The liquid gasoline from the bottom of column 31 may be stored or blended with the gasoline from the polymerization step of the process. A portion of the liquid is cooled at 53 and used as a refluxing liquid in column 25. The olefine containing gases for polymerization together with some water vapour, introduced if desired at 19 are heated in coil 60 and passed to a series of treating chambers 68, 75 containing granular solid phosphoric acid catalyst. A number of chambers may be employed in series or parallel. The successive chambers may contain catalyst of decreasing activity, the temperature of polymerization being also progressively increased. Cooling means may be provided between separate polymerizers, if desired, on account of the exothermic nature of the reaction. The products of the polymerization step are cooled and partially condensed at 78, and pass to a receiver 81 with a gas release line 82. The liquid products, augmented, if desired with butane containing gases from outside sources, pass to tower 89, from the top of which propane and lighter hydrocarbons are removed, which after condensation of all but the fixed gases, are returned to the top of tower 89 as refluxing liquid. The liquid from the bottom of tower 89 passes to a final stabilizer 106, which removes butanes overhead, most of the butanes returning after condensation, to tank 3, a portion however being used as refluxing liquid at the top of column 106. Stabilized gasoline, the principal product of the process is withdrawn from the bottom of stabilizer 106. All the stabilizers used in the process are preferably operated under pressure. Some description is given of the preparation and reactivation of the solid phosphoric acid catalysts. Specification 451,788 is referred to.