DE1543152A1 - Process for the dehydrogenation of hydrocarbons, especially paraffins - Google Patents

Description

385 Madison Avenue, New Xork, N.Y. (Y.St.A.)

Process for the dehydrogenation of hydrocarbons, especially paraffins,

The invention is directed to a dehydrogenation process and in particular to a continuous catalytic dehydrogenation process for converting paraffins to olefins and polyolefins and especially to diolefins.

The dehydrogenation of paraffins to mono- and polyolefins is normally carried out in a cycle process in reactions similar to an ohromoxide-alumina catalyst carried out. By periodically burning off the coke that has accumulated on the catalyst a reaction temperature of about 593 - 677 ° C (1100 - 12 «Ö ° F) maintain. The cycle is cumbersome, the operations are relatively short and the reactors are expensive. For example, the reaction is too Butadiene is limited, since conditions are suitable for high yields

also promote coke formation ".

The invention gives a continuous catalytic Dehydration process at, &, as by a substantial reduction the reactor costs are characterized in comparison to previously known processes and continue to be good Adaptability with regard to the sharpness of reaction is characterized.

The method according to the invention comprises preheating of the reactant stream to reaction temperature, Suspending the catalyst in the stream to form a dilute phase, passing the dilute phase therethrough a reaction zone with a contact time of about 1.5 to 4.5 seconds at a pressure of about 0.63-1 »05 ata (9-15 pounds per square inch absolute (psia)), subtracting reaction products, unreacted participants and catalyst at about 0.14-0.35 ata (2-5 psia), cooling, recovering the catalyst for reuse and recovering the reaction products.

The invention is based on the object of providing a catalytic dehydrogenation process with a relatively cheap one To create a reactor in which severe dehydrogenation conditions can be maintained for the formation of good yields of desired olefins or polyolefins. Sine others The task is to create one with a dilute phase in £ 2.u, 44JLsier $ em or firelight working dehydration

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Procedure. In particular, the invention is based on the object of an effective, powerful and economical To create a process for converting butane to butadiene.

Other features and technical advantages of the invention will become apparent from the description below in conjunction with the accompanying drawing, in which a preferred embodiment of the invention partly as a flow diagram partly as simplified section is shown. It can be seen "that the method and apparatus in the drawing are shown very schematically.

The invention is further illustrated below using the exemplary embodiment of the conversion of butane to butadiene. Fresh butane is fed in an amount of about 13,900 kg / h (30,600 lbs / hr) through line 1 and pumped via pump 2 to line 3 where it is mixed with a G ^, recycle material is fed to a line 4 and pumped in by means of a pump 5 in an amount λ of about 33,400 kg / h (73,500 lbs / hr). Since · O ^ -Rückführmaterial contains about 70 i »butanes, 26% butenes, and small amounts of butadiene, C, and C, - hydrocarbons. The combined feed of about 47,300 kg / h (104,000 lhs / hv) in line 3 is at a temperature of about 38 ⁰ O (100 ⁰ F) when it is passed through a heat build-up earlier in which it is is increased to about 82 ⁰ O (180 ⁰ F).

BATH 909831/1375

The heated feed then flows through a line 7 to a heating coil 8 which is placed in a furnace 9 and in which the feed to a temperature of about 593 ⁰ C (11 ./JO ⁰ F) to about 677 ⁰ O (1250 ⁰ F) and preferably about 655 ⁰ O (1175 ⁰ F) is heated.

The feed is passed from the furnace 9 through a conduit 10 and then divided into a plurality of parallel streams ψ . Although only two such streams are shown in the accompanying drawings, it is preferred to employ six such streams in conjunction with the amounts of feed and catalyst indicated in this embodiment. It can thus be seen that, for the sake of simplicity and clarity, only two of six streams are shown, but that a plurality of streams, such as six streams, can be used in the same way as the two streams described. It can be seen that in small plants with low throughputs only one stream to a reactor riser may be required.

As can be seen from the drawing, equal proportions of the heated charge from line 10 are in lines 11 and 12, the flow through these lines being regulated by means of valves 13 and 14, respectively. Catalyst becomes ron one generally designated 15 regenerator through lines 16 and 17, which are under the control of valves 18 bew. 19,

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deducted. The heated feed to the lines 11 and is located at about 593-677 ⁰ O (1100 - 125O ⁰ F) and the catalyst in the lines 16 and 17 is located at about 637-677 ⁰ O (1180-1250 ⁰ P) ₁ When these materials are combined, one is diluted; " ^T - ^: 'nose" on catalyst in doi ¹ charge in Heakcorlaiüüujgttij Z.0 or 21 au form and 21 lies in the range of about 0.63 - 1.05 * fcs- ( ^rj ■ * ^ ¹ ? psia) and -woT ^ n 0.84 ata (Ic. paia). Oil heater lines 20 and 21 are _t ; Iec'i about 30.48 si high with its inner diameter vy- ■ *,> · ■ '". 106.8 c" ii (3.5 solid).

The gebixueu- in lines 20 and 21. ..,: t vv; ^-: - li, _'· ..... ^ .. ^.!.' ^ .. ü X-hasC flows aafwäröa sit a icictlereü ίτβο ^ ϊ "! \ "... 24.4 ffi / atsc and vo £ zug3woiae about 1 ·:.:,. :: üi / Jfi. (^ IO I ¹ :.?« .. ^ O.; '- - ^: per second ). The 'aittlöü K & caiy-it.x ..- lic': ¹ .: - ■ · ■ r. _T :: -; L- * 5 - ^ -! 7 - "er €, 4 - 24, 1 g / l (0.4-1.50 pounds per cubic loot) and is preferably about 14.5 g / l (90 pounds per cubic foot). The Beruhrimgasait during the passage through ^ ie lines. ( 20 and 21 is in the range - "- on about 1.5 to about 4.5 and preferably about 2.1 seconds. At this point, the reaction temperature is between about (115O ⁰ F and 12; 50 ° P ) 620 ° - 677 ° C. In the reactor lines (20 and 21) -dehydrogenation occurs.

BATH ORIGINAL

In succession, butane is first dehydrogenated to buteneu and the latter are in turn dehydrogenated to butadiene. The formation of butenes is favored by a lower hydrocarbon pressure, but if the carbon dioxide pressure is reduced even further to the vacuum, the formation of butadiene is favored over the formation of butenes. A special design! ¹ form of the invention creates in an optimal manner the pressure conditions favorable for the successive dehydrogenation reactions. Thus, in the lower part of each of these reactor lines, the reaction conditions promote the formation of butenane, and in the upper part of the reactor line SD promote dia Beakticuoueliiiguiigen in entew -'- truitittaer 'fell the formation of Juüui.iaa.For example, there are condition, ungan d «r i * u ~ - ..., .->. ^,., I -... .ij? T Yes- * this execution ^ form aea procedure .. ΐ _ν ^ _'...,? «I ^:

k m Bodieu on the head

Temperature, ⁰ G ( ⁰ F) Gb2 (1225) 6 ^ 8 (12CC)

Pressure, ata (psia) D, 34 (12.0; G, 21 (3.0)

Daiapfpeel, m / sec (ft / s * c) Ψ, Οβ (13 _S ?)? 1 ₃ O5 (69.0) Katelyaatoriiohte, g / l (^ / ft ⁵ )? '., 3 (1.1? ) 3.3 (0.33) Oeeamthöho ies Tteaktors, Si (.foet)> C, ^ 8 (1CO)

The reaction products are from each of the keairtor lines 20 and 21 in two-stage cyclone separators 22 fcsw ,. in which the catalyst and reaction products are separated from one another «bnx ' i) i ⁴ uck am ο'ϋοΐ'βϋ ouex ¹ liwduktonde one

Each reactor line 20 and 21 is in the range of about 0.14 to about 0.35 ata (2-5 psia), and preferably about 0.21 ata (3 psia). 3a becomes a substantial pressure gradient sustained in lines 20 and 21 to reduce the production of butadiene in the upper section or zone to favor each of the lines 20 and 21. Gaseous reaction products are produced from the oyclones 22 and 23 Lines 24 and 25 removed, combined in a line 26 and then cooled or quenched immediately prior to any further treatment to prevent the occurrence of undesirable Prevent reactions.

The catalyst separated in cyclones 23 and 22 flows downwards therein and is stripped with dry inert gas, e.g. with nitrogen, with this in the on the ground located rinsing or stripping sections of the cyclones from an inert gas generation system 27 via a line 28 and lines 29 and 30 are introduced j the flow through the Lines 29 and 30 are opened by means of valves 31 and 32, respectively regulated. The dry inert gas strips the reaction products from the catalyst and becomes the oyclones 22 and 23 removed by lines 24 and 25, respectively.

Around 1130 star / h (40,000 standard cubic feet per hour) Inert gas can be satisfactorily used as a stripping fluid will be applied *. The stripped catalyst is passed through the gyelons 22 and 23 to standpipes 33 and 34, respectively τοη those ^ edee about 20.4 η (6 feet) high 1st. In the standpipes a dense kattlyeatorphase is maintained

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and the pressure at the exit end of the standpipes is in the range of about 1.05 to about 1.4 ata (15-20 psia), and preferably about 1.33 ata (19 psia). The catalyst flows downwards through slide valves or other suitable valve devices 35 '' or 36, which are arranged in the pipes 33 or 34, into the fluidized bed or fluidized bed regenerator 15.Air or another oxygen-containing combustion gas is released at about 1.69 ata ( 24, psia) through line 37 and a fan to the bottom or lower portion of regenerator 15 to burn down coke deposited on the catalyst. The air is heated to a temperature in the region of 635 - 677 ° C (1175 - 1250 ⁰ P) and preferably 648 ⁰ G (1200 ⁰ P) by combustion with fuel gas, for example a C, - - G ^ mixture or another suitable Hydrocarbon fuel supplied to regenerator 15 through line 39 is heated before the air flows upwardly through sieve or screen 40 into catalyst bed 41. Exhaust gas, formed by burning air and fuel gas and removing biscuit from the catalyst, flows up through regenerator 15 via a three stage cyclone, indicated generally at 42, to an outlet conduit 43. The exhaust gas is then passed through a Waste heat boiler in which heat can be recovered in the form of approximately 2725 kgA (6000 lbs / hr) of water vapor. From the boiler 44, the cooled exhaust gas is passed through a line 45 to a chimney (not shown).

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As indicated above, the catalyst separation cyclones operate at a pressure of about 0.14-0.35 ata (2-5 psia), and preferably about 0.21 ata (3 psia). The combined reactor effluent in line 26 is at a pressure of about 0.14-0.21 ata (2-3 psia) and has a temperature of about 662 ⁰ O (1225 ⁰ P). The combined effluent is cooled with a cooling material which is brought in via a line 47 under control by means of a valve 48 and is conducted to a cooling vessel 46. In this V / else be I is about 46600 kg / h (102 500 lbs / hr) to pooled effluent at 662 ⁰ C (1225 ⁰ F) to about 682,000 kg / hr (1500 COO lbs / hr) cooling material, commonly referred to as "Cooling Oil" means ^{cooled from about 110 °} C (230 ^° F). The cooling oil can be any suitable coolant consisting of a mixture of liquid hydrocarbons. The cooling vessel 46 can be suitable packing elements, for example Raschig rings or the like, or distribution devices (not shown) to promote and improve contact of reactor effluent and cooling oil included.

The cooled reactor effluent is directed from a lower portion of vessel 46 through line 49 into the lower region of scrubber 50 where it is in countercurrent contact with a cooling oil or wash medium introduced through lines 51 and 52. About 393,000 kgA (865,000 lbs / hr) of cooling oil at 43 ° C (110 ⁰ F) will be used

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through line 52 and approximately 113,500 kg / h (250,000 lbs / hr) of 38 ⁰ G (10O ⁰ F) oil is introduced through line 51. Butadiene and lighter gases are withdrawn from the scrubber 50 through an overhead line 53 in a Hate of about 51 300 kg / h (113,000 lbs / hr) to a drum 54 · through which it at about 40.5 ° G (105 ⁰ F) and about 0.14 ata (2 psia) and then discharged through line 55 to compressors and recovery equipment (both not shown). In this

P manner, about 6,900 kg / h (15,200 lbs / hr) of butadiene is produced and obtained from the plant.

From the scrubber 50, cooling oil or ash medium at about 110 ⁰ G (23O ⁰ F) through a line 56 and a pump 57 in an amount of about 1 18? 000 kg / h (2,615,000 lbs / hr) removed. A portion of the material is fed from pump 57 through line 4-7 and valve 48 to cooling vessel 46. The other part of the cooled oil is passed through a line 58 to the heat exchanger 6, in which the material is in

_k indirect heat exchange with feed from line 3 is cooled to about 96 ° G (205 ° F). The oil flows from the heat exchanger 6 to a cooler 62 where it is cooled to about 4-3 ° "'J (110 ⁰ F). This is cooled oil About 393,000 kg / h (865 000 lbs / hr) by Lines 63, 66 and 52 are fed into the cooling tower 50. The remaining 113,500 kg / h (250,000. Lbs / hr) are further ^{cooled to 38 0} G (100 ⁰ F) in a cooler 67 and into the Head of the cooling tower 50 introduced.

909831/1375

Although the invention has been described in detail above in connection with a conversion of butane to butadiene it can be seen that paraffins having 2 to about 6 carbon atoms per molecule thus convert to olefins and diolefins can be converted, depending on the operating conditions. Similarly, monoolefins can be converted to diolefins. Typical examples of other paraffins, which are suitable as feedstocks for the process are ethane, propane, isobutane and 2-methylbutane (isopentane). Furthermore, ethylbenzene can be dehydrogenated to styrene, I

As shown in the illustrated embodiment, the hydrocarbon feed comprises a mixture of about 2.5 parts by weight of return material to 1 part by weight of fresh load. However, it can be seen that this Ratio can be changed widely to 5 preferably weight ratios of 0.9 s 1 to 3: 1 are used.

In preheating the hydrocarbon feed, it is desirable to heat the feed to about the reaction temperature or to a temperature within the reaction temperature range. Preferably, the Kohlenwasserstoffbeschickuag to a temperature no longer (F 150 ⁰⁾ w than about 85 ⁰ C below the reaction temperature · -. Heated when it is mixed with hot catalyst to form Einei diluted Phaae.

Catalysts that are useful in the process were provided by a particularly preferred catalyst

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illustrated, which comprises chromium oxide deposited on aluminum oxide, the composition of which is about 18% by weight of auric oxide and the remainder being essentially aluminum oxide. While this catalyst is preferred, other catalysts known for their ability to promote the dehydrogenation of hydrocarbons, and particularly paraffins, can be used. Typical examples of such materials are: metals such as nickel, iron, cobalt, platinum and palladium; Oxides of metals of groups IVA, VA and VIA of the periodic table according to Mendeleeff, in particular chromium, molybdenum and tungsten oxides deposited on relatively inert carriers or substrates, of which aluminum oxide is a typical example. Care should be taken in connection with such catalysts that they are not used at excessively high temperatures which will substantially reduce their activity. Accordingly, temperatures below the deactivation temperature characteristic of a particular catalyst are used in the dehydrogenation reaction and during the regeneration. The preferred Chroaoxyd-Üuminiumoxydkatalysator is not higher al '732 ⁰ O (1350 ⁰ F) exposed, for example temperatures.

In the conveyor reactor lines, which are illustrated in the accompanying drawing by lines 20 and 21, a dilute phase of catalyst in hydrocarbon is maintained. Generally this becomes the phase

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between about 20 and about 50 kg of catalyst per kg of hydrocarbon, preferably about 35 - 4-5 kg / kg »contain.

Although the invention has been detailed above in connection with preferred modes of operation and preferred Conditions, it is evident that changes and modifications in the details, Work stages, materials and arrangement of parts can be made without departing from the scope of the invention.

BATH ORIGINAL

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Claims (11)

Claim 1. Process for the dehydrogenation of hydrocarbons, in particular paraffins, with 3 to about 6 carbon atoms per molecule, to unsaturated hydrocarbons with the same number of carbon atoms per molecule, thereby marked that one (a), a stream containing the hydrocarbon and the paraffin to a temperature between about 593 ° and about 677 ⁰ C - preheated (1100 1250 ⁰ F), (b) a to a temperature between about 620 ° and about 677 ° C - preheated (1150 1250 ⁰ F) dehydrogenation catalyst in the preheated hydrocarbon stream to form a dilute phase of catalyst suspended in the stream, (c) the dilute phase with a contact time of about 0.8 to about 4.5 seconds at a temperature between about 593 ° and about 677 ⁰ C (1100-1250 ° F) and at an initial pressure of about 0.63 to about 1.76 ata (9 - 25 psia) passes through a reaction zone and thereby dehydrates the hydrocarbon to the unsaturated hydrocarbon, (d) the resulting vapor products, the olefins 909831/1375 and / or containing diolefins and suspended catalyst, from the reaction zone at a pressure of about Subtracts 0.14 to about 1.05 ata (2-15 psia), (e) immediately cools the vaporous products, (F) continuously discharges spent catalyst and (g) the chilled vapor products which are the unsaturated Containing hydrocarbons, subtracts. 2. The method according to claim 1, characterized in that the hydrocarbon is a paraffin with 4-6 carbon ^ | atoms per molecule, of which at least 4 are arranged in a straight chain, regulates the reaction to form a diolefin with the same number of carbon atoms per molecule, for this purpose a contact time of about 0.8 to about 2 in step (c) , 0 seconds at a temperature between about 607 ° and 648 ° 0 ( ^{1125-1200 0} P) and an initial pressure of about 0.63-1 »05 ata (9-15 psia) and after work step (c) the resulting dilute phase directly and upwardly from the first reaction zone and upwards through a second reaction zone via a BerührungiJ-time of about 0.8 to about 2.0 seconds at a temperature between about 593 ° and about 648 ⁰ O (1100-1200 ⁰ F) and an initial pressure of about 0.42 to about 0.70 ata (6-10 psia), so that monoolefins are substantially dehydrogenated to the diolefin, the vaporous products from step (d) at a pressure of about zero , 14 - 0.35 ata (2 - 5 peia) subtracts and the Work stages (β) - (g) 'to obtain the 'BAD ORIGINAL 909831 / 137S Diolefins performs. 3. The method according to claim 1 or 2, characterized in that butane is used as the paraffin and butadiene is obtained as the olefin, the work step (b) is carried out at a temperature between about 648 ° and about 692 ⁰ G (1200-1280 ⁰ E), the work stage (c) to 677 ° C at about 620 ° (II50 - 125O ⁰ F) runs and more than 1.5 - 4.5 seconds at an initial pressure of about 0.63 - - 1.05 ATA (15 psia 9) performing step (d) at a pressure of about 0.14-0.35 ata (2-5 psia). 4. The method according to any one of claims 1-3 »characterized in that the diluted phase is up through the reaction zone passes and withdraws from an upper part of the zone. 5. The method according to any one of claims 1-4, characterized in that the catalyst density in the reaction zone holds between about 4.8 and about 48 g / l (0.3-3 »0 pounds per oubic foot). 6. The method according to any one of claims 3-5 »characterized in that the stream containing butane and n-butane Includes butenes. 7. The method according to any one of claims 3-6, characterized in that there is an association as the dehydrogenation catalyst of ohromoxide and aluminum oxide, which contain about 18% by weight odorous oxide and about 82% by weight of aluminum oxide is used. 8. The method naoh one of claims 3 - 7i thereby 909831/1375 BATH ORIGINAL in that regenerates the spent catalyst with an oxygen-containing G-as, to a temperature between about 648 ° and about 677 ° C (12C0 - 125O ⁰ F) again heated and then returns to the suspension in the preheated Buta.istrom in the circulation. 9. The method according to any one of claims 3-8, characterized in that butadiene from the cooled vaporous Products wins. 10. The method according to any one of claims 3-9 »thereby" characterized by supplying a plurality of preheated butane-containing streams and having a teaching rating of Dilute phases are formed from it, and the vaporous products are combined and cooled. 11. The method according to any one of claims 3 - 10 »characterized in that the vaporous products are quenched with oil to a temperature below about 66 ⁰ C (150 ⁰ P). RAH • 0III1 / 1S7I -WS blank page