DE1220419B - Process for carrying out the partial oxidation of organic compounds in the vapor state in the presence of heat-absorbing solids - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C07b

C07d

German class: 12 ο -27

Number: 1220 419

File number: E17128 IV b / 12 ο

Filing date: February 7, 1959

Opening day: July 7, 1966

The invention relates to a method for carrying out the partial oxidation of organic compounds in the vapor state in the presence of finely and evenly distributed in the reaction space, heat-absorbing Solids. Here, the exothermic heat of reaction that occurs during partial oxidation Organic compounds are created, controlled by a stream of finely dispersed solid particles free fall in cocurrent with the charge and the oxidizing gases as fine Let the rain trickle down. In addition, the response is automatic through appropriate regulation brought to a standstill and the solids in the upper without the use of supplied transport gas Recirculated part of the reaction vessel.

The starting materials are usually gaseous or vaporized organic compounds that can be partially oxidized. It has long been known to oxidize organic compounds in the vapor state in the presence of heat-absorbing solids, so that the invention is not limited to certain organic starting compounds. Among the organic compounds which, as is known, can be partially oxidized, there are those which contain at least 20 percent by weight of the carbon atoms in the molecule as methylene groups. The term "methylene groups" is used in a general sense and is intended to include both real methylene groups (—CH ₂ -) and methyl groups (—CH ₃ ). The starting compounds can be alcohols, ketones, amines, ethers, esters, hydrocarbons or mixtures thereof which contain the prescribed amount of methylene groups. The hydrocarbons can be, for. B. ethane, propane, butane, pentane, heptane, decanes, other aliphatic hydrocarbons, cycloaliphatic hydrocarbons such as cycloheptane, cyclopentane, cyclohexane, alkylated cycloaliphatic compounds such as methylcyclohexane, both the normal alkanes and isoalkanes are included, use. Furthermore, olefins such as propylene, butylene, hexene and higher olefins or naphthenes, the boiling point of which is between -20 and 450 ° C. or above, can be used. Particularly preferred are normal aliphatic hydrocarbons having about 5 to 10 or more carbon atoms, or naphthenes having a 5- or 6-membered ring. A relatively low molecular weight and increasing branching reduce the reactivity of a hydrocarbon molecule. Therefore, z. B. the oxidation of highly branched processes to carry out the partial
Oxidation of organic compounds in the
Steam state in the presence of
heat absorbing solids

Applicant:

Esso Research and Engineering Company,

Elizabeth, N.J. (V. St. A.)

Representative:

Dr. W. Beil and A. Hoeppener, lawyers,

Frankfurt / M.-Höchst, Adelonstr. 58

Named as inventor:

Merrell R. Fenske,

Jennings H. Jones, State College, Pa. (V. St. A.)

Claimed priority:
V. St. v. America February 28, 1958
(718 835)

Hydrocarbons, such as 2,3,4-trimethylpentane, the use of somewhat more severe reaction conditions, z. B. Pressures of at least 2 to 5 atm, while for the oxidation of normal alkanes pressures of little above atmospheric pressure are sufficient.

Aromatic compounds such as benzene, toluene and other aromatic compounds with a high concentration of nucleus, such as naphthalene, in which the methylene group content is equal to zero or less than 20% of the carbon atoms relatively inert and usually do not make good starting materials for carrying out the new one Oxidation process. If, however, an easily oxidizable hydrocarbon with the aromatic Mixing substances, both can be made reactive. In any case, aromatics can be used with contain the above-mentioned or other easily oxidizable hydrocarbons in the starting mixtures be.

Suitable starting compounds are also aliphatic alcohols, especially C ₄ - to C ₁₀ - and higher alcohols such as 1-butanol, 1-octanol, tridecyl alcohol, as well as ketones with a similar hydrocarbon content, e.g. B. heptanone-2.

As already said, the present process is about the oxidation of the organic compounds with the dissipation of the heat of reaction to be controlled so that partial oxidation occurs.

609 588/440

3 4

If you would try this heat of reaction by air or another oxygen-containing gas, z. B. moving layers, ie trickling layers of a mixture of oxygen and water vapor. Solids on solid substrates, as they are used for the purpose The various gaseous organic charges of the heat supply when cracking hydrocarbons blades are oxidized at different rates, just as substances are used to "dissipate, so those who are required to initiate the oxidation would not be successful," and the oxidation gave different temperatures, but would proceed too far. Easily ascertained even with a vortex. If the reaction layer is made up of solid particles, the reaction participant, one which oxidizes quickly, could not be controlled to the necessary extent. A well-known one, the use of oxygen-containing processes for the oxidation of ethylene or its gas mixtures, for example air or oxygen-water homologues to aldehydes, proceeds in such a way that vapor mixtures are used. shaped curved tube, in which the participant is a higher sour material concentration catalyst (activated carbon), a mixture of tration is appropriate. The device can conduct ethylene and air. The present invention 'or a "multiple feed and Sauerstoffgestattet a much more generous working and used 15 supply lines are, the number has bereieh.ii- a much wider application and the spacing of these lines from the ^design; ■ * - * ,, - · ....: ■ .. ·. ■■ -.: · - of the oxidation vessel concerned, the used

The process according to the invention also has temperatures and the type of those used

the advantage that it depends on reactants in a single reaction zone. The oxidation vessel

by means of which the solids and the charge in the 20 consists suitably of a vessel of the form

Direct current takes place. A ver of an elongated barrel and has a diameter

drive that the use of inert solids in from, for example, 1.60 to 4.5 m and a length of

Provides fluidized bed and in a number of 7.60 to 18 m.These dimensions are of course only

Reaction rooms is carried out, examples of which. - -

some are almost free of solids, the 25 As soon as the starting product and the oxidizing gas are in

inferior to the method according to the invention. When the oxidation vessel is inserted, the exo-

Application of direct current technology has an almost instantaneous opposite thermal reaction. For rapid start

the countercurrent technique has the advantage that the starting compound can be reduced to a lesser extent by oxidation

Reactors can be applied. Those for which are preheated to the reaction temperature, where-

Countercurrent technology required reactors must 30 after the oxidation is exothermic. The entrance

have a large diameter. setting of the reaction can also be

If the starting compound is easily liquefiable, the incoming solids can be on the

for example, if above - 20 ⁰ C boiling compounds for the start-up of oxidation required

are oxidized, so there are usually three types of temperature holding.

of reaction products namely gaseous, liquid 35 The temperature to be used depends on the type

sige, aqueous and a liquid organic before. That of the starting compound. It becomes a stream of

The choice of a certain starting compound is always relatively cool, when fine rain comes down.

but no decisive trickling solids together with the in the same for the partial oxidation

Factor, rather any organic direction can be used in the feed gases flowing downwards

bond that can be oxidized can be used. 40 reaction space distributed. Under "relatively cool"

An important feature of the invention is to understand that the solids entering a in that the gas velocity within a lower temperature than the exiting can vary very widely. In the case of solids, the linear gas velocity can in accordance with the invention Processes can be controlled over a wide range of gas velocities, wokeiten can be used, which can be between very low and higher or lower than the free and high velocities, reducing the rate of fall of the solids. Generally speaking, a precise and extensive regulation of the flow of the solid particles approximately with a delay time of the compound to be oxidized downwards, that of its free-fall speed Oxidation vessel, which corresponds to the temperature and the environment plus the velocity of the gases, degree of conversion per pass is possible. Man 50 The pressures used are between approximately Here, a reaction vessel of appropriate 0.5 and 17.5 kg per square centimeter can, but must Use size that is not necessarily within these limits for technical purposes. Of the is suitable. Pressure depends on the reactivity of the oxy-

Another important characteristic of an executing substance and of the scope of the other

The form of the ^ process is the automatic gas extraction. So it can be B. he

effect of the conversion that results from the downward trend, for example in the gaseous products

Directed direct current of gases and solids results in existing low molecular weight olefins, or aldehydes

(cf. the associated later explanations) and to obtain carbon oxides. The one in the oxidation vessel

the return of solids to the upper part of the prevailing pressure supports the recovery of sol-

of the reaction vessel, where they are cooled down and rather than gases, since the outflowing gases are then used for trickling solids can be reused, whereby their recovery is no longer particularly compressed

the oxidizing gases serve as the transport gas. Must be. In order to carry out an effective

If necessary, however, this type of procedure can allow the seed procedure and the gases too

be changed by the fact that a downward movement in cocurrent with the transport gas

to induce either only gas supplied from the outside or partly 65 trickling down solids,

supplied gas and partly circulating gaseous partly at the solids inlet opening a pressure

Oxidation product used. Maintain the oxidant, which can be slightly above that in the reac Oxygen, air, oxygen-enriched ion chamber prevailing pressure lies. A dif-

5 6

from 0.07 to 0.14 kg per square centimeter of iron or alumina or tungsten or molybdenum

is enough; However, it can also use a higher pressure oxide, but these metals are used

difference can be applied. of reactions of the type according to the invention not

The reaction temperature should preferably be intermediate. The solid particles usually have see about 250 and 700 ° C, but 5 needs a size between 5 and 800 μ. Particle with a this temperature range is not strictly adhered to, sizes from 50 to 300 μ have good fluidization properties. While of course for the maintenance of the and flow properties. Since the solids of the Oxidation requires a certain minimum temperature. Lower part in the upper part of the reaction vessel is, the maximum temperature depends on must be returned, they must be sufficient the type of end product. Because too strong an oxy- ίο be easy to use with transport gases. dation, which for the formation of combustion products, the velocities are conveyed upwards like carbon dioxide and water, can lead to being able to. However, it can also do heavier parts shows that the reaction participants to chen when using foreign transport gases Exposed to temperatures, it is used when operating at high speed necessary to maintain a temperature that 15 are blown through.

is below this upper critical limit. The device for carrying out these oxides in the present process, in which high through-dations, can have various shapes. A set speed as a result of high linear gas speeds can be achieved for these speeds, which work according to the direct current principle (due to the unit area of the vapor phase oxidation, a particularly suitable type of reaction vessel moving per unit of time is shown in FIG. 1 a cylindrical reactor housing 1 with the temperatures, as previously known, used upper filling device or drum 2, which with the. One of the greatest advantages of the present housing 1 is thus associated. The system is so conducive to the fact that the gas velocity is structured so that it can withstand the temperatures and pressures to be used higher than in the case of a countercurrent process. Vessel 2 contains the purpose in which the solids fall down, since in this case there is a grate 3 on which a fluidized layer according to the last-mentioned method, the speed of solids can lie. The fluidizing gas of the upwardly flowing gas not above the free is supplied via line 4,
The falling speed of the heaviest particles is a device for cooling the solid falling solids. In the case of lighter substances, which consist of the cooling coils 5 and an Ab particle, the maximum gas velocity would be gas boiler, or a similar device would be even lower. If provided for in previous procedures. Between the vessel 2 and the remit gas velocities, action vessel 1 is a device 6, which is above the specified maximum speed through which the solids are at a regulated speed, so this would mean that the solids 35 flow into the reaction vessel 1 flow. These would be propelled upwards in the reaction vessel. direction can be an ordinary valve or a control port. B. be a solid slide valve, and finally the oxidation would result as it is shown schematically in the drawing. the contact of the starting compounds with a The supply of the organic charge occurs to a large area come to a standstill. 40 via line 7 and that of the oxidizing gas

The inlet opening for the gaseous organic solids can be made of silicon-containing substances or is conveniently located above the aluminum-containing substances, such as Ottawa sand, glass inlet port for the oxidizing gas. Given pearls, spent clay, quartz, molten 45, if there are several inlet openings in longitudinal aluminum oxide or coke. These solids in the direction of the reaction vessel should be arranged in a uniform unloading, preferably opposite the loading stand from one another. The control material is inert, ie it is not used as a catalytic converter 6 is advantageously constructed in such a way that the gates are necessary for the oxidation. Your task is solids evenly within the entire Rees, to moderate the temperature in the reaction space, 50 action space can trickle down, so that the formation of hot spots or the occurrence of the desired temperature control is achieved,
The lower part of the reaction vessel 1 ends in the activity of the oxidation in the reaction space to a narrowed part 11, which is connected to a riser pipe 12 and to distribute the heat of reaction, and which is useful to absorb a smaller one, so that it has a different process diameter than the reaction vessel 1 and can be withdrawn from the solids at the top stage to open into a cyclone separator 13 in which the reaction in the riser pipe, possibly to gaseous oxidation products from the hot ones, interrupt. solid particles are separated. Above the

The size and shape of the particles should be in the general cyclone separator is the outlet pipe 14, believe to be such that they are whirled up 60 through which the gaseous oxidation products are released, however, the particles should not pull so small.

be that they are for a separation from the reaction. Furthermore, a device 15 is for recycling gas with the usual solids-gas separators, the hot solids are provided in the vessel 2, z. B. with cyclones, are unsuitable. You need to fer- this is briefly to mention that the solids that are be resistant to abrasion. If necessary, the solid 65 can be in the vessel 2 during the process in one Substances also contain catalytic substances, such as being heavily whirled up by the heat metals and heavy metal oxides which are oxidizable and drain coils 5 cooled. The pressure are reducible, e.g. B. silver, copper, platinum, chrome, above the slide valve 6 at point 16 is a

kept slightly higher than the pressure at point 17 in reaction vessel 1, which is immediately below the Slide valve 6 is located. As a result of the pressure drop within the fluidized solid layer in vessel 2 the pressure above the fluidized layer is slightly lower than the pressure above the slide valve 16 and is slightly below the pressure in reaction vessel 1. By appropriate pressure equalization can be achieved that the gases in cocurrent with the trickling down solids stream.

The solids are added to the reaction vessel and essentially flow in free fall downward into the reaction vessel 1, however, the movement of the solids through the downward flowing Gas is accelerated. By the term "free fall" it is meant that the solids do not thrown upwards by rising gas streams or hindered in their downward movement will.

It is useful to arrange grids 18 directly below the slide valve, which are more effective Achieve homogeneous distribution of the solids so that they sink in a highly dispersed, even flow drizzling down. The solids will generally be in an amount of from 0.023 to 13.6 kg per gramole of oxygen supplied. This value can, depending on the size of the solids and their physical Properties, especially with regard to their ability to withstand the exothermic heat of reaction to absorb, vary.

The linear gas velocity of the feed and the oxidizing gas is maintained so that the Total residence time in reaction vessel 1 is 0.25 to 10 seconds. Because the solids are essentially move in free fall, although their movement is somewhat accelerated by the downward flowing gas they migrate through the reaction vessel at a higher linear velocity than the gases until the gases and solids reach the riser 12, which is an upflow of the solids and the gas required. At this point the solids are moving at a rate above, which is not greater than the speed of the gases. They are caused by the gaseous oxidation products conveyed into the cyclone separator 13. The linear velocity of the gas depends on it Initial speed and from the reduction in the diameter of the riser compared to the diameter of the reaction vessel. This design feature is particularly important because it is partial Oxidations through contact with large areas are strongly inhibited or even brought to a standstill will. This is the main reason for using a cooling method trickling solids. By using trickling solids as a coolant the reaction gases are not subjected to surface contact with the solid particles to the extent that that the reaction is interrupted. When the solids reach upstream line 12 and agglomerate or become denser, the reaction will depend on the increase in solids density immediately inhibited or interrupted. This increase in density can easily be achieved by means of the gas velocity and regulate the diameter ratio between the reaction vessel and the riser tube. High speeds lead to that the solids are conveyed up through the pipe 12 without the density of the solid mass is increased considerably. At very high speeds there is even a reduction in the Solid density and the reaction continues in the riser. Run lower speeds to an increase in solids density at or near the U-shaped bend as well as throughout Riser line 12, whereby an immediate interruption of the reaction occurs. This is how you reach at Use of organic feedstocks that are difficult to oxidize by using a higher gas velocity in the riser an increase in the reaction time by using the riser as a reaction space used.

As a support for the cooling process, which works with trickling solids, through that the temperature within the reaction vessel is regulated, can also be proceeded so that one introduces the cold, liquid organic charge at several points in the reaction vessel 1. the the resulting self-cooling of the reaction mixture supports the maintenance of the desired Temperatures in it. It can also take various measures to achieve an accurate Adjustment of the gas velocities in the riser can be made. Such a measure consists in limiting the diameter of the riser in relation to the diameter of the Reaction vessel, whereby the gas velocity is accelerated to a desired degree. So must z. B. in a "system in which the reaction vessel has the same diameter as that Riser, the solids velocity necessarily decrease once the solids enter the riser and flow upwards, since the speed in the reaction vessel is about the speed of free fall corresponds to the solids plus the additional velocity of the gas, while im Riser pipe the maximum velocity of the solids corresponds to that of the gas. Even if that If the riser pipe 12 has a smaller diameter than the reaction vessel, the higher gas velocity is sufficient in the riser not enough to keep the solids in the disperse state as they do is present in the reaction vessel 1. Other means of regulating the density of solids in the Riser pipe can be applied. For example, one can proceed in such a way that one is a strange Introduces transport gas into the riser, whereby the transport gases are accelerated and the solids concentration is decreased in these gases.

Instead of using the gaseous oxidation products as transport gases, in the lower part of the reaction vessel 1, a solid gas separator device can be installed.

F i g. 2 shows the embodiment of a for separating the solids in the lower part of the reaction vessel used device, which consists of a separating vessel or separating funnel 21, which is attached to the Reactor housing 1 is attached. The solids emerging from the reaction vessel 1 fall into a the drum 21 located solid layer, while the gaseous oxidation products through the Pull off line 23. The device for the controlled discharge of solids from the drum consists of ordinary protective openings 24, which lead into the riser pipe 17, through which the solids again

get into the storage vessel 26. With this version, a foreign transport gas such as water vapor, are supplied via line 27.

In another embodiment (FIG. 3), the riser pipe 31 has a widened one at any point Part that causes a sudden decrease in gas velocity, resulting in denser accumulation of solids in this part (represented by layer 33). Afterward the cross-section 32 ι ο of the riser pipe can be narrowed at the expanded part, whereby a higher one Gas velocity and sufficient buoyancy to return the solids to the upper vessel is achieved.

The ratio of oxygen to organic loading can be relatively wider Limits, e.g. Between 0.05 and 3 moles of oxygen per mole of feed. Is the amount of oxygen in the upper part of this area, it is necessary to introduce the oxygen in several places, to prevent the formation of local hot spots and thus over-oxidation. Of the The amount of solids depends on the type of reactants used and the reaction conditions used certainly. So it is only necessary to add a sufficient amount of solids use a certain temperature within a limit, which is preferably about 700 ° C does not exceed, maintain. The upper limit of the amount of solids depends on the particular one used organic loading and must be below the amount that an inhibition or Causes interruption of the reaction.

The example describes the partial oxidation of a light, unprocessed raw gasoline (boiling range 38 to 93 ° C).

example

The filling device 2 is partially filled with alumina spheres, the mean particle diameter of which is about 300 μ. In order to obtain cooling, the bed is whirled up by introducing an inert gas and the bed is kept in contact with heat exchange coils. The reaction vessel 1 has a diameter of 2.30 m and a length of 12.20 m, and several inlet openings are arranged at regular intervals along the reaction vessel. The entire system is kept under pressure equalization by maintaining certain pressures at various points within the system. The letters A to D in FIG. 1 designate the following pressures in kilograms per square centimeter.

10

A = 7,
B = 6.95,
C = 6.20,
D = 7.35.

The solids flow at a controlled rate of 43 540 kg per minute through the slide valve 6 with a corresponding amount of air supplied of 1768 and 1190 m ^{3 of} raw gasoline per operating day, the weight ratio of oxygen to charge being 0.73: 1. After the initial supply of preheated feed, the exothermic reaction begins on contact with the oxygen. The temperature is adjusted to a range between 300 and 500 ° C. by continuously flowing the relatively cool dispersed solids downwards into the reaction vessel. After leaving the valve 6, the solids move downwards over baffle plates or grates, as a result of which they are evenly distributed within the entire reaction space. Under these conditions, the gas velocities in the reaction vessel are about 3.05 m per second, and the riser pipe has a diameter of 1.05 m. The velocity in the riser pipe is about 13 m per second. Under these conditions, the solids become relatively dense, ie their density in the riser pipe was 240 kg per cubic meter, so that the reaction came to a standstill. The density of the solids in the reaction vessel averaged about 40 to 48 kg per cubic meter. The gaseous oxidation products and the solids were conveyed into the cyclone separator 13 and the hot particles were returned to the vessel 2 for cooling, while the gaseous oxidation products were drawn off via the line 14.

After separation by cooling, the oxidation product consists of about 75.3 kg of a hydrocarbon layer per 100 kg of organic charge, the remainder from 34 kg of a water layer per 100 kg of charge and 17.9 kg of non-condensable Gases per 100 kg charge. The hydrocarbon layer contains olefins, carbonyl compounds and substantial amounts of epoxy, the water layer low molecular carbonyl compound, Alcohols and formaldehyde. The small amounts of in the oxidation product non-condensable, gaseous compounds consist of carbon monoxide and various light hydrocarbons. The product distribution is characteristic of other known processes of partial oxidation.

The table below shows the actual product distribution after partial oxidation other loads:

Respondents
η-hexane I n-hexanol 0.63
388
93
13.5
13.5 Cyclohexane Molar ratio of oxygen to hydrocarbon.
Reaction temperature ^{, 0 C}
Products as% of hydrocarbon feed
Hydrocarbon layer
Water layer 0.5
550
78
11
30th 0.75
565
80
18th
31 non-condensable gases

The most important compounds obtained are epoxides, olefins and carbonyl compounds. at the epoxies are mainly tetrahydrofurans, their trimethylene epoxy derivatives and Ethylene oxide derivatives. Some of these compounds are found in the water layer, depending on the carbon

609 588/440

Substance number of the epoxy or the molecular weight of the organic compound. Carbonyl compounds such as aldehydes and / or ketones are generally both in the hydrocarbon layer as well as in the water layer of the oxidation product.

Amount of epoxy per 100 kg charge: about 25 to 35 kg; Oxidized material, d. H. Carbonyl compounds, but also methanol: about 6 to 19 kg per 100 kg of feed. Unconverted hydrocarbons: an average of 45 kg per 100 kg load; Olefins: about 7-10 kg per 100 kg feed.

The new process is of particular importance in improving the anti-knock properties of Mineral spirits. So z. B. the octane number of a liquid raw gasoline charge according to this method from 50 to 60 to an octane value of 80 to 90 (unleaded) (Jantsch, fuel handbook, Stuttgart, Franck, 1949).

Claims (7)

Patent claims: 1. Process for carrying out the partial oxidation of organic compounds in Steam state in the presence of heat-absorbing solids, characterized in that the organic starting compounds at temperatures between 250 and 700 ° C in cocurrent with an oxidizing Gas leads down through a reaction vessel, the temperature of which is thereby in the specified Area is kept that one is relatively cool, finely divided, in the highly dispersed state, heat-absorbing flowing solids down in cocurrent with the organic feed, wherein these solid particles are distributed uniformly in one concentration throughout the reaction space kept high enough to keep the temperature within the specified range, • without bringing the oxidation to a standstill and the solids and the oxidation products withdraws from the reaction vessel, separates from each other and the oxidation products in on known way wins. 2. The method according to claim 1, characterized in that the organic charge is in the steam state. 3. The method according to claim 2, characterized in that the oxidizing gas is on introduces several points along the reaction vessel jacket into the reaction space. 4. The method according to claim 1 to 3, characterized in that the solids and gaseous Oxidation products are removed from the reaction space and the solids are removed through a riser pipe conveyed upwards by means of a transport gas, which separates solids from the transport gas, cools and returns it to the reaction vessel. 5. The method according to claim 4, characterized in that the transport gases Gaseous oxidation products leaving the reaction vessel used. 6. The method according to claim 4, characterized in, that the solids in the riser have a greater density than that in the reaction zone located there. 7. The method according to claim 2, characterized in that one to terminate the oxidation the vaporous oxidation product mixture from the reaction vessel through a relatively dense layer of finely divided solids leads to the finely divided solids of separates the oxidation product mixture and returns it to the reaction vessel. Considered publications: German Auslegeschrift No. 1 050 752,
071 084; German Patent No. 722 707; U.S. Patent Nos. 2,513,294, 2,799,359; British Patent No. 587,774; French Patent Nos. 919118, 929 006; Belgian patent specification No. 526 630 (corresponds to German interpretation No. 1 071084). 1 sheet of drawings 609 588/440 6. 66 © Bundesdruckerei Berlin