DE1768674A1 - Process for the production of olefins - Google Patents

Description

Priority: June 20, 1967 in USA Serial No. » 647 364

The invention relates to an improved catalytic dehydrogenation process for the production of olefins. In particular, the invention is concerned with improvements in the method of manufacture olefinic compounds such as styrene, sutanes and butadiene, by catalytic dehydrogenation from the corresponding stronger saturated materials using an electrically conductive catalyst such as a catalyst in which the larger component is a metal oxide which is electrically heated and kept at the desired temperature.

The production of olefins ditch catalytic dehydrogenation, such as, for example, the catalytic dehydrogenation of ethylbenzene to obtain styrene, is an endothermic reaction, and to keep the temperature in a suitable range, such as for the production of styrene between about 540 and

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65O ⁰ C (about 1000 to 120 ⁰ P), it was necessary to mix superheated water vapor with the ethylbenzene fed in and to introduce the charge of water vapor and ethylbenzene into the catalyst layer, which is aiii at a temperature in this range . This requires the use of a much larger amount of water vapor than the amount normally required to flush the catalyst free of carbon formed by the water gas reaction. There are several disadvantages to this approach to keeping the catalyst layer in the desired temperature range. Uneven heating of the catalyst layer results from the use of an excess of water vapor as a heat carrier to prevent the dehydrogenation reaction from cooling the catalyst layer below the temperature range at which the dehydrogenation reaction takes place satisfactorily. In a conventional catalytic dehydrogenation, such as the catalytic dehydrogenation of ethylbenzene to styrene, in which water vapor is mixed with the ethylbenzene charge in order to keep the catalyst layer in the desired temperature range, it is necessary to keep the top of the catalyst layer at a temperature above the optimal temperature so that the remainder of the layer is not cooled by the endothermic reaction to a temperature below the optimum for satisfactory dehydrogenation. This reduces the efficiency of the catalytic dehydrogenation reaction and leads to the formation of excessive amounts of IT by-products such as benzene and toluene. The use of large amounts of steam is uneconomical and increases the cost of the plant for the production of styrene.

BATH ORIGINAL

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Ea has now been found that the disadvantages of the prior art can be overcome, and that a more efficient process for the production of olefins such as styrene, butenes and butadiene, by catalytic dehydrogenation of a corresponding more saturated compound can be obtained that in the process

A catalyst in particulate form such as beads, granules or pellets is used and electrically heated so that the amount of steam mixed with the feed such as ethylbenzene is substantially reduced, and preferably reduced to the amount which approximates that which is required is ' Λ ' to remove any carbon formed during the catalytic dehydrogenation reaction and deposited on the catalyst. In a preferred modification, illustrated by the drawing, an electrical current is passed through the catalyst layer with the aid of plates which are mounted inside the reactor and which function as electrodes. The electrically conductive metal oxide of the catalyst has sufficient electrical resistance so that heat is developed in a sufficient amount to keep the temperature of the catalyst layer in the desired range. "

In the drawing means:

Fig.l is an elevation of the reactor showing the location of the plates in the reactor in a preferred embodiment;

Fig.l shows a cross section along the line 2-2 in Fig.l and Fig. 5 shows an elevation of an insulated power supply device.

1 0 9 8 3 1/7 7 2 η ^B * D _{Oriq! Nal}

In the drawing, and especially in Figures 1 and 2, has the reaction chamber 10, an inlet tube 12, an upper closure cap 14, which is removable, a tapered bottom portion 16, an Aualaßröhre 17, the to a not shown Condensing device leads, an outlet 18, which is closed during operation of the system but can be opened can to remove and replace the catalyst, if desired, as well as a sieve 19. The reaction chamber is in suitable particulate form with catalyst 86, such as in the form of balls, granules or pellets. Isolated power supply devices 20, 22, 24, 26, 28 and 30 are connected to the reactor wall 11 by means of screw threads connected so that their electrical lines via power distributors 32, 34, 36, 38, 40 and 42 with plates 44 and 46 in connection stand. The power distributors work in such a way that they are due to the high current density at the points where the electrical lines the insulated power supply devices with the plates are connected, prevent electrical resistance heating in the plates 44 and 46. The isolated power supply devices 20, 24 and 28 are connected in parallel with one end of a power source 48 which is a direct current or alternating current source can be. The isolated power supply devices 22, 26 and 30 are parallel to the other end of the power source switched. The electrical conductors 50, 52 and 54 are connected to the insulated power supply devices 20, 24 and 28. The electrical conductors 56, 58 and 60 are connected to the insulated power supply devices 22, 26 and 30. The reactor is filled with a catalyst in particle form, so that the ca-

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catalyzer comes into contact with the electrical plates and is supported by the sieve 19.

According to FIG. 3, an electrical conductor 70 leads through the porcelain insulation tube 72, which is composed of two parts which are held together by two metal housings 74 and 76. The insulated power supply device is connected to the reactor wall with the aid of a screw connection to the metal housing 74 connected. The electrical conductor is connected to the electrical conduit by conventional means as described in Pig.3 shown at 78.

As explained in the drawing, the current flows from the power source through the catalyst due to a potential difference between the two electrodes, which are in contact with the catalyst and separated from one another by the latter. If the If plates are relatively large in area, a better heat distribution in the catalyst layer is obtained by using them a variety of isolated power supplies and power distributors on each panel. The amount of electricity that the Catalyst layer to send depends on the desired Process conditions, such as desired throughput volume and degree of conversion.

Although in the drawing an embodiment of a plate assembly is explained, and other arrangements are also suitable, like attaching an even number of panels, soft larger than two, vertical and parallel to each other, in the direction of

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the top to the bottom of the reactor, an electric current flowing through the catalyst due to a potential difference going between alternate panels. With another modification is an even number, preferably greater than 2, of plates vertically in a spoke-like manner in the reactor. Sine spoke-like arrangement of the plates is particularly suitable for use in a reactor in which a charging Let the tube extend vertically from the top to the bottom of the catalyst bed extends so that the charge flows radially through the Kata-P lysatorschicht and into a channel around the outer Perimeter of the catalyst layer and is connected to an outlet at the bottom of the reactor. With this form of arrangement an electric current also flows through the catalyst due to a potential difference between successive ones Plates. In any of these modifications in which more than two plates are used, it is preferred to use the alternating ones Plates carrying the same charge should be connected in parallel.

_h The catalyst layer can also be used by other electrical means, such as by electrical induction

which an induction heating coil, are heated / around or in the catalyst layer can be attached. In the case of each type of electrical heater, devices are not shown in the drawing to regulate the strength of the electric current through the catalyst or in the Induktionsheizwicklur.g provided, ao that the temperature of the catalyst can also be brought to the desired temperature and kept at this can.

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Any conventional partial oxide catalyst, such as beads, granules or pellets, which is electrically conductive can be used in the process of the invention. In the catalytic dehydrogenation of ethylbenzene to styrene, a suitable catalyst made from a larger amount of 3i3enoxide, Fe _? 0 ,, and may also contain a smaller amount of potassium oxide, KpO, and a smaller amount of a heavy metal oxide, such as chromium oxide, Cr ^ C-. The preferred catalyst for the production of styrene by dehydrating ethylbenzene is in pellet form and contains about 93% , "» Pe ₃ O ₅ , about 5 # ^Cr 2 ° 3 ^{and about 2} ^ ^K 2 ^0%

In the following examples, 12-hour ethylbenzene dehydrogenation tests are carried out using a reactor with plates, corresponding to the plate arrangement in Figures 1 and 2 of Drawing carried out with direct current flowing through the catalyst layer is sent. All percentages are by weight.

The effectiveness of a dehydration attempt is determined by dividing the weight of styrene produced by the weight of ethylbenzene which has been destroyed or converted into other substances such as benzene, toluene and styrene.

The styrene yield is calculated by dividing the weight of produced Styrene determined by the weight of ethylbenzene in the feed.

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example 1

A current of 800 amperes and 21 volts is sent through the catalyst and provides 16.8 kW of electrical heat. The catalyst layer is made of pellets with a diameter of 4.8 mm (3/16 ") by a length of 4.8 mm (3/16") of a catalyst with an Fe ₂ 0., Content of 93 / », a Cr ₂ O, content of 5 "/ * and one of 2 #.

A stream of steam and ethylbenzene charge, in which the ratio of steam to ethylbenzene charge is 2 1/2 to 1 lb., is passed through the catalyst bed at a rate of 0.40 lbs. Of ethylbenzene charge per hour per lb. of catalyst. The flow of water vapor and Äthylbenzolbeshickung at the inlet at a temperature of 638 C (1180 ⁰ P). The temperature of the catalyst layer during the test is at the top of 621 ⁰ C (1150 ⁰ F), in the middle of 602 ⁰ C (1115 ⁰ F) and in the bottom 599 ° C (HLO ⁰ F). The composition of the Äthylbenzolbeschickung 0.3 5 ^ benzene, 0.8 io toluene, 93.8 i »ethylbenzene and 5.1 # styrene.

The dehydrogenation product is fractionated by distillation and is composed of 2.65 # benzene, $ 5.99> toluene, 31.72 # ethylbenzene and $ 59.62> styrene.

The effectiveness of the experiment is 92.1 # and the yield is Styrene 67 ^.

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BATH ORIGINAL Example 2

An ethylbenzene dehydrogenation test is made in the same reactor and in the same manner as in Example 1 with the exception that a current of 700 amps and 20 volts is passed through the Katalyaatorachicht and provides electrical heat of 14.0 kW. The ratio of water vapor to ethylbenzene feed is 2 lbs: 1 lbs. The stream of steam and ethylbenzene feed is passed through the catalyst bed at a rate of 0.33 lbs of ethylbenzene feed per hour per pound of catalyst. The stream of steam and Äthylbenzolbeschickuryg is SiOH at a temperature of 627 ° 0 (1160 ⁰ F) at the inlet, and the temperature of the catalyst layer is at the top of 593 ° C (1100 ⁰ P), in the middle of 593 ⁰ C (HOO ⁰ P) and at the bottom 604 ⁰ C (1120 ⁰ P). The dehydrogenation product is composed of 3.16 # benzene, 9.89 fo toluene, 15.79 $ ethylbenzene and 71.16 $ styrene. The effectiveness of the experiment is 82.1 $> and the yield of styrene 68.6 ^c / o,

Example 3

An ethylbenzene dehydrogenation experiment is carried out in the same reactor and carried out in the same manner as in Example 1 except that a current of 800 amps and 21 volts through the catalyst layer is conducted and provides 14.4 kW of electrical heating. The ratio of water vapor to ethylbenzene feed is 1.3 lbs: 1 lbs, and the flow of water vapor and ethylbenzene is through the catalyst layer in one Rate of 0.40 lb. of ethylbenzene feed per hour per lb. of catalyst passed. The stream of water vapor and Ethylbenzene feed is at a temperature of

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632 ⁰ C (117O ⁰ P) at the inlet. The temperature of the Katalyaatorachicht during the experiment is at the top 613 ⁰ C (1135 ⁰ F), in the middle 602 ⁰ C (1115 ⁰ P) and at the bottom 602 ⁰ C (1115 ° P). The Zuaammenaetzung the Äthylbenzolbeschickung is 0.2 ^v ß> benzene, 0,6 # toluene, 93.5 1 »ethylbenzene and 5.7 # styrene. The dehydrogenation product is composed of 3.5 Ί "benzene, 7,2 i" toluene, ethylbenzene and 27.5 # 61.8 $> styrene.

The effectiveness of the experiment is 81.1 # and the % yield of styrene is 58.1 #.

The results of Example 3 show that a high conversion of ethylbenzene to styrene is achieved with a steam-to-oil ratio that the calibration approaches what welohea through the water gas reaction is necessary for the complete removal of carbon deposited on the catalyst.

Comparative example

b An ethylbenzene dehydrogenation experiment is made in the same reactor and in the same manner as in Example 1 except that electric current is not passed through the catalyst layer. The ratio of water vapor to ethylbenzene feed is 2 lbs: 1 lb. The stream of water vapor and ethylbenzene feed is not passed through the catalyst at a rate of 0.33 lbs of ethylbenzene feed per hour per pound of catalyst. The flow of water vapor and Äthylbenzolbeschickung is at a temperature of 627 ⁰ C (1160 ⁰ P) at the inlet, and the catalyst layer Temperabr

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BATH ORIGINAL

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^{is 593 0} C (1100 F) at the top ^{, 616 0} C (1140 ^{0 P) in the middle and 593 0} C (HOO ⁰ F) at the bottom.

The Dehydrierungeprodukt is from 2.32 ° ß> benzene, 4.74 # toluene, ethylbenzene 37.89 * ■ assembled and 55.05 i ° styrene. The effectiveness of the experiment is 84.6? Ί and the yield of styrene 51.5 <-c

ORIGINAL

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Claims (1)

J / B8674 i · a t e η t a η s ρ r ü c h e 1.) Process for the production of olefins by catalytic dehydrogenation of the corresponding more saturated materials, using an electrically conductive catalyst in particulate form in which the larger component is an I.Ietalloxyd, characterized in that the catalyst is heated with the aid of electrical devices and on the desired temperature is maintained. . ':'.) Method according to claim 1, characterized in that an electrical 3trom is passed through the catalyst. 5.) Method according to claim 1 and 2, characterized in that a electric current is passed through the catalyst by making a potential difference between an equal number of at least;: white. Electrodes that are in contact with the catalyst and are separated from each other by this. ··.) Method according to claim 1, characterized in that the Catalyst is heated by electrical induction. 5.) The method of claim I to 4, characterized in that one inn by the dehydrogenation of ethylbenzene styrene wins. 6.) The method according to claim 5, characterized in that? ι \ -λλ an IlfitHlysat or used, which holds a larger proportion of I-'errioxyJ »jr. 109831/7072 bad original / bfcJB'M Y.) Vtiri / uhroti after Αηαη.πιοη b, thereby ^ ekenn ^ oicLnot, dai3 one a-'ai ilataL.yuator used, which has a smaller I.iöiiv'o an Kaliiuaoxyd unl eitie the smaller ilen, ;; e an 'Jhruwoxyd contains. : '>.) Vtiri'ahren nacli An-jpruoli »> uni 7, thereby kennaeichnei, <i & k one uses a Katalyoabr, which is in a ier;' form of pellets and about 9.r-; ' i '"e /) ,, -about ':>'* Cr ₁ O ,. and ecv / a .. '> K ₀ O contains ,. 109831/2072 Blank page