DE1518919B1 - Process for the cleavage of olefins - Google Patents

Description

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According to the invention one proceeds in a characteristic manner that of the cleavage temperatures, that of the Spal mode in such a way that the olefin is used from about 0.001 to about mill by the process according to the invention Seconds temperatures of about 400 to about det are not noticeably split. The Ver-

900 ⁰ C in the presence of methyl mercaptan in quantitative ratio of diluent to be spaltendem gene of about 0.4 to about 50 mole percent based on 5 olefin which can be used according to the invention,

the weight of the olefin. can, if a diluent is used,

That which is used according to the invention within wide limits of about 0.5: 1 to 15 or

Methyl mercaptan acts as a conversion accelerator more moles of diluent per mole of olefin changed

by a mechanism other than becoming sulfur. However, if a ratio is greater than

hydrogen and the higher alkyl mercaptans. It is used io 15: 1, outweighs the improvement achieved

In this connection it was found that the costs no longer arise, and that

The reaction is based on the radical mechanism. The process would become uneconomical. It will

runs, the active radical but not the SH radical therefore usually prefers, a volume ratio

but is the CH ₃ S radical. Finding this diluent to olefin ratio of about 1: 1

Facts to be used according to the invention together with an improvement in the 15 to about 3: 1 or 4: 1

Yield, etc. is quite surprising. the.

The cleavage of the olefins according to the invention can be carried out in any conventional manner, which is usually insignificant and can be used between about 1 mm Hg of the olefin cleavage technique. The an- to about 35 atmospheres fluctuate. It is preferred, however, that the conditions employed can generally be varied within wide limits in practicing the method of the present invention and are not essentially used for pressures of about 1 atm to about 7 atm. They usually depend on the particular one. In carrying out the olefin to be cleaved according to the invention and in the particular processes, it is generally usually preferred products. The cleavage temperature admits to use oxygen-free conditions, e.g. B. within wide limits of about 400 to 25. It has been found that the amount of about 900 ^° C. in the invention can be changed. In carrying out methods according to the invention as Olefinpyrolysebeschleuniger but it is preferred to employ temperatures used methyl mercaptan over a wide of 500 to 800 ⁰ C, and it is more may be loading area. Of course, sufficient should preferably, temperatures are employed accelerator of from about 600 to about 75O ⁰ C in order to apply with respect to the. The time during which the olefins are in the cleavage zone to obtain an improvement by thermal pyrolysis can, according to the invention, be as little as 0.4 or 0.5 mol percent methyl mercaptan, or about 0.001 to about 3 seconds. Depending on the total amount of olefin, the particular olefin to be cleaved and the particular olefin proved to be sufficient. Excellent results will be desired, however, products can last this time if about 3 to about 10 mole percent methyl is changed for about 0.05 to about 1 second and 35 mercaptan is applied. Although it is very preferred for the veres to use residence times of about 0.1 to the utilizable amount of methyl mercaptan no upper about 0.5 seconds. Given these time limits, it has been observed that when used, residence times are usually referred to, ie, of more than 50 mole percent, if any, only one residence time in the cleavage zone; they are achieved as the small improvement that can be made, which defines the length of time it takes 1 molecule of inflowing gas, 40 extra cost for which more than about 50 mole percent Me reactants, diluents, or both, ethyl mercaptan would warrant, to pass through the cleavage zone. As stated above, the invention is directed to process zone as the zone in which, in order to accelerate or improve the effectiveness of the above-mentioned cleavage in the cracking of olefins, the temperature is increased. 45 generally cleavable by thermal cleavage processes The olefins which are cleaved according to the invention, ie olefins which, if they are to be according to the invention, can generally be subjected to the process in pure form or in bulk processes, are present on the mixed coal with other hydrocarbons. The substance-carbon single bond that is to be cleaved to the olefins to be cleaved can also be located with an inert double bond in the ^ position. It is on the diluent to be mixed. It is usually so most expedient to carry out the process according to the invention appropriately to carry out an inert diluent with those olefins which are to be used when the olefins are cleaved according to the process according to the invention. The expression have a single bond and which have such a configuration "inert diluent" denotes a material configuration that during decomposition they do not significantly convert products that are not significantly formed with the olefin to be cleaved, which mainly consist of diolefins Cleavage bothers. In the same examples of olefins with a double bond way, the diluent must not come into contact with the carbon-carbon single bond, desired products that are formed by cleavage under the conditions of the decomposition as the main product, 1,3-butadiene cleavage, or with if they are cleaved according to the invention in the presence of cleavage accelerators used in the cleavage process, methyl mercaptan are converted into hexene-2, niger. In addition to 3 - methylpentene-1, pentene-2, cyclohexene, 3 - medem, the diluent should not itself be cleaved or decomposed under the cleavage conditions used, ethylbutene-1, 2-heptene, 3 - methylhexene -1, 5 -. Examples of ethylhexene-2,2-octene, 5-methylhepten-2, 3,5-dimethyl for diluents which can be used according to the invention hexen-1, 3,4,4-trimethylpentene-1, 6-methylhepbar are steam, carbon dioxide, Water-5sten-2, Nonen-2 and 3-methyloctene-1. Substance, nitrogen, inert gases such as helium, neon and examples of olefins with an argon double bond or paraffin hydrocarbons such as methane, β - carbon - carbon - single bond ethane or various other hydrocarbons, which form the main product in the decomposition 2-Me-

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Form 1,3-ethylbutadiene or isoprene if it was made according to the outer diameter. This snake should be in the presence of methyl mercaptan in a bed of flowable heat transfer gaps, 2 * methylpentene-2,3-methylpen powder are embedded. The heat transfer powder pray - 2, 2 - ethylbutene - 1, 3,3 - dimethylbutene - 1, stood out from microspherical alumina-silica-2,3 - dimethylbutene -1, 2 - methylhexene - 2, 3 - Me- 5 powder that usually as a cleavage catalyst ethylhexene - 2, 2 - ethylpentene - 1, 2,3 - dimethylpen- serves. The heat transfer powder was both th -1, 3,3 - dimethylpentene -1, 2 - methylheptene - 2, by electrical resistance heating as well as by 3 - methylheptene - 2, 2 - ethylhexene - 1, 3,3 - dirne- burning a natural gas flame directly heated in powder ethylhexene -1, 2,5 - dimethylhexene - 2, 3,5 - dimethyl fluidized bed. The temperature gradient from the upper hexene * 2, 4 - methyl - 2 - ethylpentene - 1, 2,3,4 - tri-io end to the bottom of the bed was nowhere more than methylpentene -1,3,3,4 - trimethylpentene - 2, 2 - Me- about 5 to 6 ° C, and the temperature gradient from thyloctene - 2, 3 - methyloctene - 2, 3,3 - dimethylhep fluidized bed to the tension zone was also nirten - 1, 2,5 - dimethylheptene - 2, 2, 6 - Dimethylhep- gends more than about 5 to 6 ⁰ C, the temperature in the th - 2, 5 - methyl - 2 - ethylhexene -1, 3,3,5 - trimethyl fluidized bed was hexed-1 and 2 by means of conventional thermocouples, 5,5-trimethylhexene-2. 15 measure. The cleavage coil was equipped with the usual thermal examples for olefins with a double bond moelement and the temperature in the split - permanent carbon - carbon single bond zone was also measured using the usual thermal modulation, which is the main product element during decomposition. The method used was 2-Äthylbutadien-l, 3 form, when it is the heat transfer powders are subjected by the elekin presence of methyl mercaptan of the cleavage 20 Irish resistance heaters to about 500 ⁰ C, are according to the invention 3-Äthylpenten-2, 2-ethyl- and at the same time swirling through the bed with pentene * 2, 3 - methylhexene - 3, 3 - methyl - 2 - ethyl. Then a direct natural gas butene - 1, 3 - ethylhexene - 2, 3 - methyl - 2 - ethyl-air flame was used to generate the heat transfer penten-1. To bring bed to the desired cleavage or working examples for olefins with a carbon-carbon temperature. The natural gas flame and the single substance bond> the one in / ^ - position to the double combustion products as well as additional air have been bonded, which is used as the main product to swirl the powder bed during decomposition. The Be-2,3-dimethylbutadiene-1,3 form, if they are faster in accordance with the invention or the methyl mercaptan are cleaved with the olefin to be cleaved in the desired molar ratio in the presence of methyl mercaptan, are 2,3-dimethylpentene-2,3-methyl -2-ethyl- 30 nis mixed before the olefin was passed through the cleavage zone butene -1, 2,3,3 - trimethylbutene -1, 2 - isopropylpen-. Water and the olefin, which may contain beet-1, 2,3,3-trimethylpentene-1 and 2,3-dimethyl accelerator, were found in the corresponding hepten-2. the rates required to set the examples for olefins with a carbon-carbon ratio of water vapor to carbon single bond required for the double bond / S position 35 hydrogen, and with a rate required for decomposition as the main product 3 -Methyl- total speed pumped around that the pentadiene-1,3 form when they are cleaved according to the invention in the desired residence time of the materials in the cleavage presence of methyl mercaptan, zone resulted. The pressure used was almost Atsind 3 - methylhexene - 3, 3 - ethylpentene - 2, 3 - atmospheric pressure. After all the variables had been ethyl - 2 - ethylbutene -1, 3 - methylheptene - 3, 3,4 - di - 40 and the desired Arbeitsbedinmethylhexen - 2, 3 - methyl - 2 - ethylpentene - 1, were reached, the Cleavage products 3,6-dimethylheptene> -3. Catched, if they were liquid, by means of cold traps, examples of olefins with a carbon-carbon and, if gaseous, they were measured at atmospheric pressure with a single bond, which was in the / ^ position to double and room temperature. The bond that has been trapped is the main product of the decomposition. 45 Products were analyzed for content and yields by customary analytical methods. For the purpose of ascertaining 1,3-form, if according to the invention they are given in counterpart of the total yields which are cleaved as the overall type of reaction of methyl mercaptan, the usual back-hexes-3, 2-ethylpentene-1, 2,3-dimethylpentene »1 , management practices applied. The 2,4-dimethylpentene-2, 2-methylheptene-3, 4,4-di-5 ° yields per pass are given as yields per pass of methylhexene-2, 2-propylpentene-2, 2-methyl.

- ethylpentene - 1, 2,6 - dimethylheptene - 3 and The results of these experiments as well as the working 2-propylhexene-1. conditions are compiled in the table below for examples of olefins with one to the double bond, in which in column 1 the test number,

/ 5-carbon-carbon single bond, 55 in column 2 the residence time in seconds, in column 3 the

the temperature used in the decomposition as the main product piperylenes, in column 4 of the given

form if they are used according to the invention in the presence of accelerator and its amount, if used, in

Methyl mercaptan are cleaved, hexene-3, column 5 is the isoprene yield, given in molpro-

- methylpentene - 2, heptene - 3 _S 4 - methylhexene - 2, cent mol of 3-methylpentene-2 supplied, whereby octene - 3, 4 - methylheptene - 2, 6 - methylheptene - 3, 60 this figure relates to the yield per pass refers to - ethylhexene - 1, 4 - methyl - 3 - ethylpentene - 2, and in column 6 the total yield in mol percent 4,5 - diniethylheptene - 2 and 4,5,5 - trimethylhexene-2. of isoprene obtained per mole of 3-methyl-

The practice of the invention is pentene-2 using conventional recycle techniques the following experiments, which were exclusively used, are given. borrowed to be exemplary. 65 In each of these examples, the educated persist

All experiments were products of isoprene and methane in a fission arrangement. All yields carried out, the work and efficacy of a »Haamadek serpent relate to the educated which was made of a stainless steel tube with 0.6 cm isoprene.

7th temperature Accelerator and amount 8th Isoprene yield
per round Effective
sameness attempt
No. Dwell time ⁰ C Mole percent Seconds 667 15.6 61.2 1 0.15 661 CH ₃ SH 8 mole percent 20.9 72.1 2 * 0.15 672 - 16.9 61.7 3 0.15 681 - 19.1 60.4 4th 0.15 678 (NH ₄ ) ₂ S 8 mole percent 25.7 63.4 5 0.15 684 CH ₃ SH 8 mole percent 26.5 77.0 6 * 0.15 702 CH ₃ SH 8 mole percent 37.0 64.1 7 * 0.15 700 - 26.2 58.0 8th 0.15 663 CH ₃ SH 8 mole percent 20.3 57.3 9 * 0.14 703 CH ₃ SH 7.5 mole percent 33.7 51.9 10 * 0.13 643 CH ₃ SH 8.4 mole percent 14.9 59.5 11 * 0.14 663 CH ₃ SH 7.3 mole percent 34.0 56.9 12 * 0.24

* Designates tests in which CH ₃ SH accelerator was used; the remaining experiments are control experiments and show the thermal pyrolysis of 3-methylpentene-2.

Pyrolysis of 3-methylpentene-2 obtained as well as the yield per pass.

As can be seen from the table above, comparable results can be obtained for other work

the production of isoprene by pyrolysis of 3-measuring conditions can be obtained. Improvements will be

ethyl-pentene-2 in the presence of methyl mercaptan - also in the cleavage of other olefins after the

Eighth improvements were obtained both in terms of the method according to the active ingredient.

Claims (2)

1 2 The term "configuration" is here the position or claims: position of the double bonds and the position and type of side groups, if any, of the 1. Process for the cleavage of olefins, which is understood in apt olefins. Let this be with one of them Molecule explains a carbon-carbon example: An olefin with 6 carbon atoms shed bond that is in / S position to and a methyl side group on the second carbon double bond stands, in the presence of a mer atom of the main chain and a double bond in captans as a cleavage accelerator, thereby ge 2-position, d. H. 2-methylenepentene-2, forms when it indicates that the olefin undergoes about 0.001 cleavage when decomposed as up to about 3 seconds temperatures of about 400 io Main products a diolefin, isoprene or 2-methylbis about 900 ° C in the presence of a methyl mer-butadiene-1,3, and a paraffin of lower molecular captan in amounts of from about 0.4 to about 50 molar weight; d. H. Methane. On the other hand, one forms percent, based on the weight of the olefin, of 6 carbon atoms containing olefin having a set will. ethyl group on the second carbon atom of the main 2. The method according to claim 1, characterized in that the chain and the double bond in the 1-position, 2-methyl, that for the production of isoprene 2-mpentene-1, in the cleavage two main products ethylpentene-2 about 0.05 to about 1 second of a low molecular weight olefin, isobutylene and Temperature from about 600 to about 750 ° C in ethylene. The configuration of the present in detail from about 3 to about 10 mol percent of me- used olefin therefore generally determines the type methyl mercaptan is exposed. 20 of the main or predominant products that make up the cleavage of the olefin arise. These differences with regard to the Retained products are based on the fact that olefins are attached to the carbon-carbon single bond 25 are split, which are present to the double bond in ^ -position, d. i.e., the cleavage of the olefin The invention relates to a method for cleavage occurs at the bond that is in / ^ - position to of olefins that have a carbon double bond in their molecule or that cleavage takes place Contain carbon single bond in / 3-place between the carbon atom of the olefin, which is with ment to the double bond, in the presence of a double-bonded carbon atom ver mercaptan as a splitting accelerator. is bonded, and the adjacent carbon atom. It is known that most olefins are thermally It is known that in the application of the for can be decomposed or cleaved by cleavage of olefins with the formation of low molecular weight exposed to relatively high temperatures. Products favorable conditions with sole on-under the expressions "cleavage", "decomposition", 35 expression of high temperatures the olefins with "Pyrolysis" and the like are to be understood as meaning that the olefin ring rate per passage through the Spalmolecule can be decomposed solely by the application of a high temperature zone. The split of the oleratures is split into two fragments (these fine-influencing conditions are the actual temperature thermal pyrolysis depends on the dehydration in the cleavage zone, the residence time in the zone to differentiate between the effect of an upper 4 ° and that which may be used surface catalyst as well as high temperature ratio of olefin to diluent, to effectively remove hydrogen from the purpose of increasing the overall yield, one can use molecules with the formation of unsaturated molecules, if necessary after appropriate separation, the are required). These fragments themselves put unreacted olefin back into the process again Recycle molecules with other, smaller molecular 45. Due to side reactions or weight, the carbon as well as water decomposition does not succeed here, pro Contain material atoms. This state of affairs will after- passing through the cleavage zone more than about explained in more detail below. To implement the thermal decomposition 45 mol percent of the starting compound, Conversion or cleavage of the olefins is usually used for the cleavage of olefins of the specified type in a closed zone, or a reactor at 5 ° is already known, as a gap accelerator temperatures up to about 1000 ⁰ C a mercaptan throughput of about 300 to apply (British Patent out. This pyrolysis is usually in the absence 916,133). The low molecular weight unit of oxygen is carried out here. Normally, mercaptans from ethyl mercaptan to hexyl the olefins are split in the gaseous state; They are called mercaptan and also hydrogen sulfide, which can form the SH radical either as a relatively pure compound under the cracking conditions that are used or in a mixture with other hydrocarbons, which acts as an accelerator, usually in a mixture with a saturated one. Hydrocarbon, d. h., you can z. B. from a The relevant previously known method could Starting mixture of pentene and pentane run out, but not yet completely satisfied, as either or in a mixture with diluents such as stick-60 the yields of the desired diene, in particular matter, steam, etc., are split. Isoprene, were relatively low or the effective As stated above, the pyrolysis of the olefins causes the isoprene formation to be unsatisfactory. The inventor ordinary the task of forming two substances with a smaller manure is thus based on a process Molecular weight, both carbon and water, to create the specified kind, which makes it possible Contain material atoms. What products lower Mo-65 the yield and effectiveness of the process too the molecular weight formed during the pyrolysis of olefins while halting the formation, depends largely on the configuration of the desired by-products with the shortest possible verdes the olefins subject to cleavage. Under the dwell time in the split zone.