Patent GB-597086-A (GB)
Title: Improved process for the dehydrogenation of hydrocarbons
IPC: C07C5/333
Filed: 1944-04-25
Abstract: <PICT:0597086/III/1> <PICT:0597086/III/2> Olefins are dehydrogenated to diolefins or alkyl benzenes to styrenes by introducing separate streams of the vaporized hydrocarbon and steam simultaneously into a mixing zone provided adjacent to one surface of a bed of dehydrogenation catalyst in a reaction zone, the hydrocarbon stream being below and the steam above reaction temperature, the mixture being forced at once into and through the catalyst, and the products quenched immediately by a quenching fluid to a temperature below that at which further reaction occurs.  Butenes heated to 1200-1250 DEG F in furnace 3, and steam superheated to about 1400 DEG F in heater 12 pass to reactor 21 by pipes 5, 14.  Means 102 and 90 control the fuel feeds to the heaters in accordance with the outlet temperature of the butenes and steam respectively.  Butenes enter a ring manifold 18, Fig. 2, and steam a similar manifold 30, draw off pipes 19 from manifold 18 leading to mixing means 22 such as venturi tubes disposed in pipes 24 projecting into manifold 30, so that solids in the steam are prevented from entry.  Butenes and steam, preferably in a volume ratio of 1 : 8-10, are mixed in said means 22 and pass at about 1200-1300 DEG F into an annular bed of catalyst 25 disposed between perforated members 34, 401.  Hoods 33, having sleeves 40 adapted for vertical adjustment on the lower ends of the mixing nozzles, contact member 34 to direct the gases through the catalyst.  Steam under pressure enters by line 91 and prevents butenes leaving the catalyst bed.  Products are cooled to 900-1000 DEG F by water sprayed through nozzles 100, and leave by way of a ported ring 104 and pipe 42.  The catalyst may consist of MgO, Fe2O3, CuO, and K2O in percentages by weight of 50-95, 3-49, 0.5-10, and 0.5-10, preferably 72.4, 18.4, 4.6, and 4.6 respectively.  Contact times may be 0.05-2, preferably 0.5 secs, the butene partial pressure being 25-200mm. Gaseous products are further cooled to say 500-600 DEG F. in waste heat boiler 45, cooled with quench oil from line 49 and again with oil at 150-200 DEG F. fed down tower 50 from pipe 54.  This oil is cooled in 63 and re-cycled, part being continuously rejected after removing butadiene and butenes in stripper 69 for recycling to tower 50.  The gases then pass through condenser 58, are separated in drums 62 from liquid, quenched with water in tower 75, and passed to condenser 82, and fractionation, butadiene extraction, and purification equipment. Two or more reactors are generally used.  Catalyst is regenerated by passing steam at 1100-1300 DEG F. obtained by partly by-passing super heater 12 by means of line 15, hot waste gases being utilised in boiler 45. The temperature of the butenes and/or the steam may be increased as the activity of the catalyst decreases.  The contact time may be varied by changing the amount of catalyst.  The pipes 19 and 24 are adjustable to maintain contact of the hoods 33 with different thicknesses of catalyst bed.  In starting up, steam condensation is prevented by passing heated air first and displacing this with steam.ALSO:<PICT:0597086/IV/1> <PICT:0597086/IV/2> Olefins are dehydrogenated to diolefins or alkyl benzenes to styrenes by introducing separate streams of the vaporized hydrocarbon and steam simultaneously into a mixing zone provided adjacent to one surface of a bed of dehydrogenation catalyst in a reaction zone, the hydrocarbon stream being below and the steam above reaction temperature, the mixture being forced at once into and through the catalyst, and the products quenched immediately by a quenching fluid to a temperature below that at which further reaction occurs.  Butenes heated to 1000-1250 DEG  F. in furnace 3, and steam superheated to about 1400 DEG  F. in heater 12 pass to reactor 21 by pipes 5, 14.  Means 102 and 90 control the fuel feeds to the heaters in accordance with the outlet temperatures of the butenes and steam respectively.  Butenes enter a ring manifold 18 (Fig. 2), and steam a similar manifold 30, draw-off pipes 19 from manifold 18 leading to mixing means 22 such as venturi tubes disposed in pipes 24 projecting into manifold 30 so that solids in the steam are prevented from entry.  Butenes and steam, preferably in a volume ratio of 1 : 8-10, are mixed in said means 22 and pass at about 1200-1300 DEG  F. into an annular bed of catalyst 25 disposed between perforated members 34, 401. Hoods 33, having sleeves 40 adapted for vertical adjustment on the lower ends of the mixing nozzles, contact member 34 to direct the gases through the catalyst.  Steam under pressure enters by line 91 and prevents butenes leaving the catalyst bed.  Products are cooled to 900-1000 DEG  F. by water sprayed through nozzles 100, and leave by way of a ported ring 104 and pipe 42.  The catalyst may consist of MgO, Fe2O3, CuO and K2O in percentages by weight of 50-95, 3-49, 0.5-10 and 0.5-10, preferably 72.4, 18.4, 4.6 and 4.6 respectively.  Contact times may be 0.05-2, preferably 0.5 secs., the butene partial pressure being 25-200 mm.  Gaseous products are further cooled to, say, 500-600 DEG  F. in waste heat boiler 45, cooled with quench oil from line 49, and again with oil at 150-200 DEG  F. fed down tower 50 from pipe 54.  This oil is cooled in 63 and recycled, part being continuously rejected after removing butadiene and butenes in stripper 69 for recycling to tower 50.  The gases then pass through condenser 58, are separated in drum 62 from liquid, quenched with water in tower 75 and passed to compressor 82, and fractionation, butadiene extraction, and purification equipment. Two or more reactors are generally used.  Catalyst is regenerated by passing steam at 1100-1300 DEG  F., obtained by partly byepassing superheater 12 by means of line 15, hot waste gases being utilized in boiler 45. The temperature of the butenes and/or the steam may be increased as the activity of the catalyst decreases.  The contact time may be varied by changing the amount of catalyst. Pipes 19 and 24 are adjustable to maintain contact of the hoods 33 with different thicknesses of catalyst bed.  In starting up, steam condensation is prevented by passing heated air first and displacing this with steam.