GB770541A - Process for the catalytic conversion of heavy hydrocarbon oils - Google Patents

Abstract

<PICT:0770541/III/1> In a process for the catalytic cracking, hydrocracking (i.e. destructive hydrogenation) or hydro-desulphurization of high-boiling hydrocarbon oils in the presence of a dense fluidized bed of catalyst particles at elevated temperature, the hydrocarbon oil is sprayed on to the top of the catalyst bed, whereupon the more volatile componnets of the oil are vaporized (to an extent of not more than 25 volume per cent) without conversion, and the vaprous conversion products are passed into a second fluidized bed of catalyst which may be of the same or of a different activity and/or temperature as that in the first bed. Heavy gas oil, heavy coal tar oil, heavy shale oil, and reduced crude petroleum oil may be treated by the process. Suitable catalysts for hydrocracking are vanadium oxide, nickel, nickel oxide, tungsten, tungsten oxide, nickel tungstate, cobalt molybdate, molybdenum oxide and tungsten sulphide. The catalyst is preferably supported on a suitable carrier such as alumina, silica-alumina, or acid treated montmorillonite clay. The apparatus shown, which is suitable for the hydrocracking of reduced crude oil, comprises three reactors 14, 38, 50; two of which are on-stream while the catalyst in the third is undergoing regeneration. In the following description, reactors 14 and 38 are initially on-stream, while catalyst-regeneration is taking place in reactor 50. Reduced crude having an initial boiling point of 550 DEG F. is preheated to about 700 DEG F. and introduced through line 10 into reactor 14. A dense bed of fluidized catalyst, comprising nickel tungstate on alumina, is maintained in reactor 14 by hydrogen-containing gas introduced through lines 18 and 22. A pressure of 500 lbs. per square inch and a temperature of 800 DEG to 850 DEG F. are maintained in the reactor. The hydrocarbon oil is discharged in the form of droplets ( 1/8 to 1/16 inch in diameter) above the bed of catalyst, thereby avoiding clumping of the catalyst particles. A mixture of vaporized feed, vapours of hydrocracked products and fluidizing gas leaves reactor 14 through cyclone separator 26 and line 28. The vapour mixture then passes through valve 30 to line 32, where it may be supplemented by further amounts of hydrogen-containing gas from line 34. The vapour mixture then enters reactor 38 wherein it maintains a bed of catalyst (nickel tungstate on alumina) in the dense-fluidized state. The temperature in reactor 38 is 750 DEG to 950 DEG F. The final hydrocracked products, which include gasoline, together with fluidizing gas leave the reactor 38 through cyclone 40, and are withdrawn from the system through line 48. Meanwhile contaminated catalyst is being treated in reactor 50. Hydrocarbons and hydrogen-containing gases are purged from the contaminated catalyst bed by introducing flue gas into reactor 50 through lines 52 and 56; the purging gas leaving the reactor via cyclone 58 and line 68. Means (not shown) are provided to condense out the hydrocarbons from the purging gas. At the end of the purge, valve 54 is closed, and air plus flue gas is introduced into the reactor through lines 72 and 56; and oxidation regeneration of the catalyst takes place at a temperature of 1000 DEG -1200 DEG F. The regeneration may be effected either at high pressure or at low pressure. After the bed of catalyst in reactor 50 has been regenerated, it is re-purged with flue gas from line 52. The activity of the catalyst in reactor 38 will now have declined and it is subjected to purging and regeneration, while reactor 50 is brought on-stream. Valve 70 is closed, and reduced crude oil and hydrogen-containing gases are supplied, via lines 82 and 80 respectively, to reactor 50 which is then maintained under the hydrocracking conditions already stated. Hydrocracked vapours and vaporized feed pass from reactor 50 through line 60 and the mixture is fed through line 22 into reactor 14, which now acts as the second on-stream reactor, so that the final hydrocracked products are withdrawn through line 95. Finally, reactor 38 is brought on-stream again (this time as first reactor), while the catalyst in reactor 14 is being regenerated. In the system described the most active catalyst is in the reactor into which the feed is sprayed. If desired, by simply rearranging the piping, the feed can be introduced initially to the reactor containing the less active catalyst.