GB996428A - Low pressure hydrocracking process - Google Patents

Abstract

Hydrocracking of a mineral oil containing nitrogen and/or sulphur is effected by catalytic hydrofining over a sulphactive transitional metal catalyst and passing the total effluent without purification over a hydrocracking catalyst comprising a Group 8 metal hydrogenating component at 400-2000 p.s.i.g. Hydrofining is effected conventionally over oxides and/or sulphides of Group 6 and 8 metals at 600-850 DEG F., 400-2000 p.s.i.g., 0.3-20 v./v./hr. and 500-20,000 SCF/B hydrogen. Hydrocracking is effected at 600-800 DEG F. rising to 650-875 DEG F., 400-2000 p.s.i.g., 0.5-10 v./v./hr. and 500-15,000 SCF/B hydrogen. The effluent is washed with water to remove ammonia and hydrogen sulphide and fractionated to recover hydrogen, hydrocarbon gases, gasoline product and higher boiling material. This may be recycled to the hydrocracking or passed to a second hydrocracking step or may be fractionated into light and heavy gas oils, e.g. with a cut point of 500-600 DEG F. and if gasoline is the principal product desired the light oil is passed to the second step and the heavy oil recycled or if a jet fuel-diesel fuel range is desired the light oil is recycled and the heavy oil passed to the second step. The second step may be preceded by a hydrogenation treatment at 400-725 DEG F. over a Group 6 or 8 metal to prevent build up of polycyclic aromatics. The second hydrocracking may then be effected at below 725 DEG F. and conditions otherwise similar to the first hydrocracking. Both hydrocracking steps are preferably effected over an aluminosilicate catalyst, e.g. a 6-14 <\>rA molecular sieve, preferably containing hydrogen and/or divalent metal cations and promoted with platinum, palladium, ruthenium, rhodium or iridium preferably introduced by ionexchange. The use of refractory oxide cracking bases, clays and aluminium phosphate is also mentioned.