GB766404A - A process for the production of gasoline and related lighter products by means of hydrogenation and catalytic cracking - Google Patents

Abstract

<PICT:0766404/III/1> In a process for cracking petroleum distillate oils boiling above the gasoline range, the oil is divided into two portions, one of these portions is subjected to catalytic hydrogenation under such conditions that there is an uptake of hydrogen amounting to between 100 and 700 cubic feet per barrel of oil-being-hydrogenated without any material lowering of the average molecular weight of the oil, and the hydrogenated oil and the unhydrogenated oil are then submitted to catalytic cracking in the same reactor, whereby gasoline is produced. The required hydrogen may be derived from a naphtha-hydroforming unit. Crude desalted California petroleum (1000 barrels) is topped in section 1 to give straight-run gasoline and a residue. The gasoline is fractionated in section 2 to produce light gasoline, which is removed at B, and also 200 DEG -400 DEG F. naphtha. This naphtha is passed to section 3 wherein it is hydroformed, at a temperature of 800 DEG to 920 DEG F. and a pressure of 700 p.s.i., in the presence of hydrogen and a platinum catalyst deposited on HF-treated alumina. The hydroformed naphtha, which has an octane number of 89, is removed at C. Hydrogen, 730 cubic feet per barrel of naphtha is also produced in section 3. The residue from the topping section 1 is passed to section 4 where it is vacuum-flashed to give a distillate and a pitch-residue. The distillate is passed to fractionator 5, wherein it is separated into light and heavy fractions (275 barrels of each). The lower boiling fraction is passed to unit 6 wherein it is hydrogenated with the product gas from platforming unit 3. The hydrogenation is effected at a temperature of 710 DEG F. and a pressure of 750 p.s.i., and in the presence of a tungsten nickel sulphide catalyst. The hydrogen uptake is 284 cubic feet per barrel of light flashed distillate. The hydrogenated light distillate is combined with the heavy flashed distillate; and the mixture is cracked in the vapour phase at 930 DEG F. in unit 7 which contains synthetic silica-alumina catalyst. The increase in the value of the products is more than 50 per cent higher than for the prior art process where the total flashed distillate is hydrogenated with the same hydrogen consumption.