GB776022A - Method for regenerating stationary beds of catalyst - Google Patents

Abstract

Catalyst particles having carbonaceous deposits thereon are regenerated by burning off the deposits by simultaneously passing a regenerating gas comprising oxygen and an inert diluent gas through each of <PICT:0776022/III/1> a series of stationary beds of said catalyst, a mixture of liquid water and gas containing oxygen being introduced between successive beds to cool the combustion gases and restore the proportion of inert diluent gas to gas containing oxygen, and removing the total combustion gases from the final bed of the series. In Fig. 1, illustrating preferred embodiments of the invention, which shows a series of stationary beds of successively larger size in proportion to the successively increasing volumes of regeneration gas, arranged within a single containing vessel, a mixture of diluent gas (steam or flue gas), and air in suitable molar proportions (diluent: oxygen=99-96:1-4) is passed into the uppermost bed having a foraminous covering layer 16 e.g. consisting of several inches of porcelain or alumina spheres at a temperature near the minimum required to support the combustion of the deposited coke (7-800 DEG F.), and emerges through a foraminous supporting element 10 at a temperature near the maximum which can be employed without damaging the catalyst (1000-1300 DEG F.). Water (atomized with fresh quantities of air to provide the original preferred diluent:oxygen ratio) entering intermediate chamber 30 cools the combustion gases back to 7-800 DEG F. and after passing through baffles 66 the procedure is repeated in bed 6: bed 8 is similarly regenerated and the total combustion gas is withdrawn at 64. The quantities of air and water entering intermediate sections 30 and 32 are regulated by temperature responsive means associated with control means 56, 58, 60 and 62 and may amount to 25-30 per cent by volume of the combustion gases. Upward passage of the regeneration gases is permissible. Such a series of beds may be one of a plurality connected in parallel and regulated by valves so as to permit the sequence in each series:-regeneration, steam purge, depressure/repressure, reaction, hydrogen purge, depressure/repressure, steam purge, regeneration &c., whilst in the plurality of said series, each series is at a different point in the sequence, the maximum number of series of beds being at the reaction phase. A system of this type using reactors similar to that in Fig. 1 is described in detail, in connection with the hydrodesulphurization at about 833 DEG F. and 1000 p.s.i.g. of a hydrocarbon comprising 71 per cent by weight vacuum tar bottoms from the distillation of a Kuwait crude oil and 29 per cent by weight of catalytically cracked furnace oil derived from the distillation of Kuwait crude, having an API gravity of 10.7 degrees and having a sulphur content of 4.87 per cent, with an initially oxided nickel-tungsten combination containing 9 per cent by weight tungsten and 3 per cent by weight nickel deposited upon a commercial alumina carrier to give a liquid hydrocarbon oil product of lower sulphur content and of higher API gravity. The invention can be used in conjunction with hydrodesulphurization or destructive hydrogenation of heavy or light hydrocarbon oils over nickel, its oxides, sulphides, molybates and tungstates, molybdenum oxide, molybdenum sulphide, tungsten oxide of tungsten sulphide; catalytic cracking of hydrocarbon oils over bauxite; desulphurization of hydrocarbon oils over bauxite; reforming and hydroforming of hydrocarbon oils including any of the reactions therein involved (e.g. hydrogenation, cracking, isomerization and aromatization) over catalyst such as molybdenum oxide, nickel and cobalt; the above catalysts may be supported on silica-alumina, alumina, activated clays, magnesia or kieselguhr.