GB791072A - Combined hydrocracking and hydroforming process - Google Patents

Abstract

In a process for the production of gasoline from heavy petroleum fractions of the kind in which the heavy petroleum fraction is hydrocracked to produce a naphtha and the naphtha is hydroformed under hydrogen pressure to produce gasoline and the hydrogen used in the cracking process, the hydrocracking is performed in presence of metals of the palladium (Ru, Rh, Pd) and platinum (Os, Ir, Rt) series supported on a synthetic composite of solid oxides of at least two elements from Groups IIa, IIIb, IVa and IVb of the Periodic System at temperatures from 400-825 DEG F., at a liquid hourly velocity between 0.1 and 10, in the presence of hydrogen under pressures from 100 lbs. p.s.i. to 2500 lbs. p.s.i., and using a molar ratio of hydrogen to hydrocarbon charge varying from 2-80, the aforesaid conditions being regulated so that there is a net consumption of hydrogen, while the reforming stage is carried out in presence of a platinum or palladium catalyst as described in Specification 790,476. Gas oil and hydrogen recycled from line 18 are mixed and compressed in a compressor 17 from which they are passed through a heater 21 to a hydrocracker unit 10 filled with the hydrocracking catalyst. The cracked products pass to a gas separator 11 from which gases are separated and the hydrogen recovered is recycled through line 19. Liquid products pass through a depressurizing zone 25 to a fractionator 12 from which gases are removed through line 27 and light naphtha through line 27 while the heavy naphtha is fed through line 29 in admixture with recycle hydrogen supplied through line 42 to a pressurizer 41 and heater 44 and thence into the reforming unit 13. The reformed products pass to a separator 14 and thence to a fractionator 15 from which the reformed gasoline is recovered through line 52. Hydrogen produced in the reforming process is recycled through line 47. In Fig. 2 (not shown) a tar separator operated in conjunction with the plant shown above enables the process to be operated with a crude of broad boiling range. The catalysts used in the hydrocracking zone are described in Specification 791,073 and have a surface area of from 650 to 100 square metres <PICT:0791072/III/1> per gram and comprise from 0.05-2 per cent platinum or palladium deposited on silica containing from 0.025 to 7 per cent alumina. Gas oil boiling in the range 416-622 DEG F. mixed with hydrogen in the molar proportions of hydrogen to hydrocarbon of 9.5 was charged to a hydrocracking unit containing as catalyst 2 per cent platinum on a silica-alumina carrier containing 10 per cent alumina at a liquid hourly space velocity of 1.1, the temperature being maintained at 610-635 DEG F. and the pressure at 500 lbs. p.s.i. A 46 per cent conversion of the charge was obtained of which 50 per cent was the C4-gasoline cut. The 180-420 DEG F. fraction was reformed at 850 DEG F. in the presence of a catalyst comprising 0.23 weight per cent of platinum on a silica-alumina carrier of low surface area and of hydrogen under a pressure of 500 lbs. p.s.i., the proportion of hydrogen to hydrocarbon being 10 and the hourly space velocity 3. 96.8 per cent of the charge was converted to gasoline of octane number 98 while 1570 cubic feet of hydrogen were produced per barrel of reformed charge, the net yield of hydrogen being 410 cubic feet per barrel of initial oil charge which was used to supply part of the hydrogen requirements for the hydrocracking stage, there being a net consumption of 370 cubic feet of hydrogen per barrel in the entire process.