DE2236508A1 - PROCESS FOR THE MANUFACTURING OF ARYL-SUBSTITUTED NORMAL PARAFFINS - Google Patents

Description

The invention relates to a process for the preparation of aryl-substituted normal paraffins and in particular an improvement in a procedure for the production of aryl-substituted normal paraffins in which an η-paraffin is present a dehydrogenation catalyst is dehydrated, the resulting n-paraffin / monoolefin mixture with a monocyclic aromatic Compound is alkylated and a paraffin stream recovered from the effluent from the alkylation is used for the dehydrogenation reaction is returned.

A serious problem in densely populated areas around the world is the disposal of sewage that V / ash or cleaning agents or similar surface-active agents Substances (detergents; hereinafter referred to as detergents) contain. This waste disposal problem is particular pronounced in the case of wafers which have an alkylaryl structure

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have in the core of the molecule. These detergents produce stable foam in hard and soft water in such quantities that the foam can clog sewage treatment facilities and often occurs in concentrations so high that it destroys the bacteria necessary for adequate biological action in wastewater treatment. A group of The main harmful substances of this type of detergent are the alkylarylsulfonates, which in contrast to the fatty acid soaps don't fail when using calcium or magnesium ions hard water containing it. Furthermore, since these compounds are only partially biodegradable these detergents are in solution and are dragged through the waste water treatment plant in largely unchanged form. As a result of the tendency to foam, especially when mixing with ventilation devices and stirrers, get there Large quantities of these detergents from sewage treatment plants in rivers and streams, where there is the presence of the Detergent shows through large piles of foam on the surface of these bodies of water. Other difficult connections Such detergents are the polyoxyalkylated alkylphenols and the alkylphenol-polyoxyalkylamines. These synthetic Detergents - also interfere with the anaerobic degradation process of other substances, e.g. lubricating greases - and thus intensify furthermore the pollution caused by such detergent-containing discharges of waste! se ran lay is caused. These Dilute detergent solutions often enter groundwater streams and thus get into groundwater supplies, many of which Cities meet their water needs so that the alkylaryl-based detergents eventually end up in the water intended for the Supplying the population in households, factories, hospitals, schools and the like is used.

It has been found that the biological deficiency

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The buildability of the detergent ultimately used largely depends on the arylalkyl compound used for its manufacture the detergent is used. In particular, it has been shown that these detergents more easily and quickly through sewage bacteria are degradable when the long-chain alkyl substituent on the aromatic nucleus has a simple straight-chain configuration having. From the point of view of biodegradability, the preferred precursor or intermediate is therefore an aryl-substituted one Normal paraffin. There is therefore a great need for hydrocarbons of this type. Since hydrocarbons of this type are usually produced by an alkylation, they are often called "detergent alkylate" in the field or, denotes "linear detergent alkylate"; this includes, for example, linear alkylbenzenes.

As is known, linear detergent alkylates can be processed into a wide variety of detergents. The detergent alkoxide can for example be sulfonated and then neutralized with a suitable alkali base, e.g. with sodium hydroxide, to produce an alkyl aryl sulfonate as an anionic type detergent; such detergents have widespread use for household, technical and industrial purposes. The detergent alkylate can also be detergents of the nonionic type processed, by nitration of the alkylate to form an intermediate mononitrated in the core, which upon reduction gives the corresponding alkylarylanine. The amine residue will then with an alkylene oxide or an alkylene epichlorohydrin a polyoxyalkylated alkylarylamine, which preferably contains 4 to about 30 oxyalkylene units, reacted? such connections are very effective detergents. Another A large group of detergents made from detergent alkylate are the oxyalkylated phenol derivatives; here an alkylphenol base substance becomes a9 Phe- "

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nols manufactured. There are several other products known based on alkylaryl. The alkylarylsulfonates, however, represent the largest class of surface-active substances that normally be synthesized from such detergent alkylates.

Due to the great need for linear detergent " alkylate, processes have been developed in which normal paraffins are used as the starting material for the straight-chain alkyl substituents on the aryl nucleus. A manufacturing route for that Detergent alkylate proceeds via the selective catalytic dehydrogenation of normal paraffins to the corresponding ri-monoolefins, which therefore have the same carbon number, followed by an alkylation of an aromatic compound with the obtained n-monoolefin using an acidic catalyst; aryl-substituted n-paraffin hydrocarbons are obtained. For the dehydration stage, η-paraffins are normally used which contain about 9 to about 20 carbon atoms, so that n-monoolefins with the same number of carbon atoms are obtained. Has the alkylation stage two results; first, to produce the desired arylalkyl hydrocarbon, and second, to facilitate the Separation of the olefin produced as the product from the unreacted n-paraffins fed to the alkylation stage. In this process step, a dehydrogenation catalyst is preferably used which, on the one hand, has a high selectivity for the production of n-monoolefins and, on the other hand, has the ability at the same time has undesired side reactions such as skeletal isomerization, secondary hydrogenation, cyclization, dehydrocyclization, poly * merization, cracking, etc., to suppress. Since equilibrium considerations, the conversion levels in the dehydrogenation stage inevitably limit, it is necessary for an economical process to carry out the unconverted n-paraffins from the mixture of reac-

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recovery participants and products and to the dehydration reaction traced back. For example, typical conversion levels are in the dehydrogenation step can be achieved with a preferred catalyst, in the range of about 5 to about 20 weight percent of normal paraffin, depending on the temperature, pressure, catalyst activity and the like. Preferably, the "unreacted Paraffins pass through the alkylation zone, where they remain essentially unchanged, and then separate them out the products of the alkylation reaction by fractional distillation.

A problem with such processes * is that the catalyst used for the dehydrogenation of the η-paraffins to which n-monoolefin is used accordingly, is subject to deactivation. This deactivation requires a steadily increasing sharpness of reaction in order to maintain the transformation, and / or a relatively frequent regeneration of the catalyst. Both measures are disadvantageous because one Regeneration interrupts generation and increases operational severity often reduces the selectivity. There has therefore long been a keen interest in technology for development of operating modes that prevent the deactivation of the catalytic converter and thus both the operation and the ' improve the economics of the process.

The invention is based on the object of providing gin processes for the production of aryl-substituted normal paraffins. the Desaktivlorung of is reduced for the catalytic dehydrogenation of ^1-η Para iff inen used catalyst, thereby increasing the life of the catalyst and facilitates the administration and maintenance performance of the overall process and vorbilligt. Here «should this

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through simple, operationally reliable and fault-free measures take place.

In the process, a combination of normal paraffin dehydration takes place and alkylation with recycle of recovered from the dehydrogenation and alkylation steps n-paraffins are used in the dehydration step. It it was found that even very small amounts of aryl-substituted η-paraffins in this n-paraffin recycle stream unexpectedly a strong »Deüaktivierur.g of the dehydration · bring about a catalyst. If. "" Omit in the A.lky zone generated aryl paraffins in the recycle stream to the ka.t-ilytic Dehydrogenationzoms are passed, even very small amounts of AryIparaffinen lead to an excessive catalyst deactivation. A · »elimination of the difficulties succeeds in a technically simple manner by such a control of the operating conditions in the on the alkyl. Lerungb - zone following separation zone that less than 0.1 percent by weight of aryl paraffins are passed into the hydrogenation zone, Dibel can this control of the operating conditions in the l'ronnzone 'lurch known Msilnalunen take place.

The status of the invention is therefore an ancestor for the production of aryisubstituLortan I'or.T.alparaffinen, at the

(a) A paraffin and wafer on a dehydrating catalyst in a dehydration zone. " to an n-monoolefin with

a Kohlenstoffz.ihL equal to that of eingcnutzttm I'arafflnu _f vorliegtiiu! in Gi "mi3ch with non umgebet Ttem n ^ Parif-, fin, implemented v / ground,

(b) da »n-monoolefin / n-paraffin-Gemitch and elna monocycli 3Che aromatic compound on an Alkylieinngsk.it.iIyaator in an alkylation zone and an aryl-substituted one n-paraffin, mainly in a mixture with unreacted monocyclic aromatic compound and not

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converted η-paraffin, are converted,

(c) the mixture of aryl-substituted η-paraffin, monocyclic aromatic compound and η-paraffin in a separation zone with deduction of an n-paraffin recycle stream, containing small amounts of aryl-substituted η-paraffin, is separated, and

(d) the n ~ paraffin recycle stream for conversion in the dehydrogenation zone is returned,

which is characterized in that the operating conditions in the separation zone by per se known measures regulates such that the amount of aryl-substituted η-paraffin in the n-paraffin recycle stream is so low it is kept that the n-paraffin passed to the dehydrogenation zone contains less than 0.1 percent by weight of aryl-substituted n-paraffin. ■

The n-paraffin is preferably a paraffin or a mixture of paraffins with about 9 to about 20 carbon atoms, especially 9 to 15 carbon atoms. A catalyst based on aluminum oxide, which is about 0.01 to 1.5 percent by weight, is preferably used as the dehydrogenation catalyst Lithium, about 0.05 to 5 percent by weight of platinum and about Q '/ oil to 1 percent by weight of arsenic contains:' used ', However, any other known dehydrogenation catalysts can also be used can be used, but catalysts of the platinum-alkali metal type are particularly suitable. As an alkylation catalyst is e.g. Suitable for hydrogen fluoride. Benzene is the preferred monocyclic aromatic compound »

The compounds which are responsible for the aforementioned deactivation of the dehydrogenation catalyst are those contained in the n-paraffin feed stream ^; aryl-substituted paraffins. As a result of the measures characterizing the invention, the deactivation rate is

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Dehydrogenation catalyst in the dehydrogenation zone considerably decreased.

In a typical industrial practice, the alkylation zone effluent is placed in a fractionation zone separated, with the n-paraffin recycle stream as the overhead product is recovered from a fractionation column in which the η-paraffin is derived from the aryl-substituted paraffin produced is separated. The amount of aryl-substituted paraffin contained in the paraffin recycle stream withdrawn overhead is determined by adjusting the reheater temperature accordingly and the amount of reflux introduced into the top of the fractionating column. For example can be done either by lowering the reheater temperature and / or by increasing the reflux / feed ratio the amount of aryl substituted paraffin in the paraffin recycle stream can be reduced. .. *

Further aspects, preferred measures and achievable advantages can be found in the following Explanation.

The term "aryl-substituted n-paraffin", as used here denotes a secondary aryl substituted one Alkane, the two straight chain alkyl groups on the resulting triple attached to the aryl nucleus substituted carbon atom, e.g .:

r \ '

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In the formula, R. and R denote η-alkyl groups. The expression "η-paraffin" or - "straight-chain hydrocarbons" denotes; » net hydrocarbons whose carbon atoms are continuous Chain with no branches and no appending groups connected U

Suitable starting materials are normal paraffins with at least 9 carbon atoms and in particular 9 to about 20 carbon atoms per molecule. Examples include: Nonati _f decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane and mixtures thereof. Normal paraffins with about 9 to about 15 carbon atoms are particularly suitable, since the monoolefins produced therefrom result in detergents of superior biodegradability and cleaning action. A mixture, which comprises four or five successive homologs, for example C ₁₀ - c._, C - C .. or C. -. C, represents an excellent feedstock Furthermore, the amount of non-■ '.- normal hydrocarbons , which is present in this normal paraffin load, kept low. Vorzugsiweise the Normalparaffinboschickung more than 90! Weight percent of n-Paraffinkohlcnwasserstoffen should consist, ι best results are erzielt.- at purities ranging from 96 to _t 98 weight percent or above

'It may contain up to 20 carbon atoms, any starting material that normal paraffins having from 9 to be used for the delivery of the Normalpäraffine used in the method. These include, for example, fractions of the corresponding boiling range of straight run petroleum distillates, products of the Fiachsr-Trppsch synthesis, which include paraffinic hydrocarbons in the C- - C_ range, hydrogenation products of ethylene polymerization with paraffins of 9 to about 20 carbon atoms, and hydrogenated fatty acids, which at full- , constant reduction of paraffin hydrocarbons more straight-chain

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Configuration result. The most readily available and generally preferred source of normal paraffins in the C "- C ₂ range is a kero3in fraction in the boiling range of from about 149 to about 260 ° C (300-5OO ° F), especially a fraction in the boiling range of about 177 to about 232 ° C (350-450 ° F). If paraffins originating from hydrocarbon distillates are used, it is generally preferred to subject the fraction to a pretreatment by any known hydrogenation treatment process for the substantial or complete removal of sulfur-containing and nitrogen-containing compounds with closer saturation of olefinic compounds In order to obtain freshly dried coal distillate, it should preferably be annihilated or completely saturated and essentially free of nitrogen and sulfur.

When using a Dor.tillate from petroleum must be the normal paraffin from a hydrocarbon mixture be separated, the lorric paraffine, Iscparaffino and containing cyclic compounds. Because of the Kledo point overlap this various hydrocarbon carton can a fractional distillation is usually not sufficient Effectiveness can be applied so that separating substances that are used to separate compounds fold misappropriating the carbon structure «; structure are able to be used. Such separating substances are known and are called molecular sieves designated. The preferred molecular sieves for these Separation task are dehydrated iMetallalumlnosillcate, their Aluminosilicate crystals have zeolite structure and pores of about 5 angstrom units in diameter; the latter are of sufficient size to withstand normal paraffinic compounds to admit four or more carbon atoms, but not of sufficient size to permit entry of branched-chain ones

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or to allow cyclic compounds. The metal compo-. Components of these zeolites are normally selected from the group. of the alkaline earth metals, preferably calcium or magnesium. These molecular sieves are normally made by the reaction or interaction of silica, alumina, an alkaline base and water to form a zeolitic hydrous alkali aluminosilicate which precipitates from the aqueous solution as a mass of fine crystals. The recovered alkali metal derivative of the hydrated zeolite is then usually ion-exchanged with an alkaline earth metal salt and dehydrated by calcination to form the desired molecular sieve. .

A suitable separating device can be operated according to the bed changeover method, in which two separate treatment columns are provided, each with separate inlet and outlet lines. The extraction of normal paraffins is carried out in one of these columns, while at the same time the regeneration of the sieve particles and the recovery of the normal paraffins take place in the other treatment column. In this mode of operation, the normal paraffinic stream flows either up or down through a fixed bed of molecular sieve material with the substantially straight chain components entering and being retained in the pore structure of the molecular sieve particles while the abnormal hydrocarbons pass through the bed. The treatment is carried out at atmospheric pressure or above and at temperatures of about 21 to 149 C or above (70-300 ^O F '), depending on the boiling point of the stream containing the normal paraffins. The molecular sieve bed located in the normal paraffin recovery stage of the circuit is treated with a displacement medium, usually a normal paraffin; of lower molecular weight than the normal paraffine or paraffins that are used for dehydration

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tion of the present proceedings are to be obtained. For example, η-butane or n-pentane can be used to displace the heavier normal paraffins from the pores of the molecular sieve particles. Flowing the displaced heavier normal paraffins from the column off and are usually a Fraktionierkolonne.zugeführt in which the Verdrängungsmediura is separated the resulting substantially pure normal paraffin hydrocarbons are then passed to the de _Vi hydrogenation zone. , ,,

According to a preferred mode of operation, a separating device is used which continuously produces n-hydrocarbons of non-normal hydrocarbons in simulated continuous operation according to the rules of the USA patent 3 310 486 separates. In this mode of operation, the molecular sieve is arranged in and through a sequence of extraction zones Applying a sequence of switching operations creates a countercurrent flow the molecular sieve beds are simulated in relation to the hydrocarbon stream to be cleaned. that in this multi-bed system the individual beds are at rest and by constant switching of the inflow and outflow points what is achieved is that normal paraffins are continuously extracted in part of the facility and at the same time in a treatment for the recovery of normal paraffins is carried out in another part of the facility. Accordingly is the Essentially pure normal paraffins drained from the device practically continuously. Details of this Working methods are unnecessary for understanding the process described here and can otherwise be derived from the USA patent. .. ·. ,,.

Suitable catalysts for the dehydrogenation step of the present process generally include one or more metal components from groups VI and VIII of the

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Periodic table or! Compounds thereof - The catalysts usually comprise a support material of one or more resistant inorganic oxides such as alumina, silica, zirconia, magnesia, etc. Particular care should be taken that the catalyst used in the dehydrogenation zone does not Isomerization of the normal paraffins or the resulting olefinic product is favored. Accordingly, the catalyst is preferably rendered non-acidic by the incorporation of one or more alkali or alkaline earth metals or compounds thereof. Furthermore, the conversion to the desired monoolefin is improved, if noble metals, the Group VIII has been used, with platinum being particularly preferred. A particularly preferred catalyst for the dehydrogenation step comprises an alumina support, a metal component of the platinum group, an alkali or alkaline earth metal component or compounds thereof, and a component selected from the group consisting of arsenic, bismuth, antimony, sulfur, Selenium, tellurium and their compounds. . · "

The aluminum oxide support of the preferred dehydrogenation catalyst generally has an apparent bulk density less than 0.5 g / cm, with a lower limit of about 0.15 g / cm. The surface properties are appropriate so that the mean pore diameter is about 20 to 300 Angstrom units, the pore volume is about 0 ', 10 to 1.0 ml / g

2 and the surface area are about 100 to 700 m / g. This alumina support may be prepared according to "any suitable method, in particular the known method for the preparation of Aluminiumoxydkügelchen, as described in US Patent 2,620,314.

The alkali component of this preferred dehydration catalyst can from the group of alkali metals cesium, rubidium, potassium, sodium and lithium and from the Group of the alkaline earth metals calcium, magnesium and strontium

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can be chosen, with lithium being the preferred alkali component forms. The alkali metal is in abundance in relation to elemental Metal, present at less than about 5 percent by weight of the total composition, with a content in the range from 0.01 to about 1.5 weight percent is generally preferred. The alkali component can be the aluminum oxide in any suitable heat, in particular by treatment with an aqueous impregnation solution »suitable Compounds are the chlorides, sulfates, nitrates, acetates, carbonates and the like, e.g. lithium nitrate. The contribution can either before or after the addition of the other components or during the formation of the aluminum oxide, e.g. addition to the alumina hydrosol prior to the formation of the alumina support material.

The metal bodies-to the platinum group can be general made of palladium, iridium, ruthenium, rhodium, osmium or Pass platinum, with platinum giving the best results. In addition to platinum, the catalyst can also have a metal component of group IVb included. This component is found in a concentration, calculated as an element, from about 0.05 to about 5 weight percent of the catalyst composition used. the mentioned metal components can be introduced in any suitable manner, the impregnation with a water-soluble compound such as chloroplatinic acid is particularly preferred will.

The fourth component of the preferred dehydrogenation catalyst3 consists of arsenic, antimony, bismuth, sulfur, selenium, tellurium and their compounds. Arsenic is particularly preferred. This component. Typically used in a quantity from about 0.01 to 1 weight percent of the final composition is used. This fourth component is preferably in an atomic ratio to the Group VIII metal component

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from about 0.1 to 0.8 present. Located in the middle area Concentrations are preferred so that the atomic ratio is about 0.2 to 0.5. This component can also be in any are introduced in a suitable manner, particularly preferred is impregnation with a solution of a water-soluble Compound such as arsenic pentoxide or the like.

The preferred catalyst combination explained

Settlement is then normally subjected to conventional drying and calcination at temperatures in the range of 427 to 593 ° C (800 - HOO ⁰ F). Further details on the preferred dehydration catalyst for the process are given in U.S. Patents 3,291,755 and 3,310,599.

Any convenient alkylation catalyst can be used are used for the alkylation stage of the process. Typical examples are sulfuric acid with a concentration of about 85% and preferably higher, substantially less anhydrous Hydrogen fluoride, generally containing no more than 10% water, anhydrous aluminum chloride or aluminum bvomide, preferably in the presence of the corresponding hydrogen halide, Boron trifluoride, either with or without the addition of hydrogen fluoride and either directly or in adsorbed form on a solid support material, e.g. an inorganic support material modified with boron trifluoride, phosphoric acid, ■ usually deposited on a carrier material such as kieselguhr, silicon dioxide or the like hydrate, and similar catalysts. The preferred catalyst for the present process is anhydrous hydrogen fluoride at a concentration of 90% or higher; Another preferred catalyst is the aforementioned boron trifluoride.

Details regarding concentrations, applications, etc. this preferred alkylation catalyst

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Ren are unnecessary for the method described here, they are for the boron trifluoride catalyst, for example, in the United States patent 3 200 163 stated.

A preferred embodiment of the method is further illustrated below in conjunction with the accompanying drawing. The drawing shows a schematic Flow sheet for the production of aryl-substituted paraffins from an n-paraffin feed. The latter was made after the above outlined working method with simulated countercurrent flow (U.S. Patent 3,310,486). The information on normal paraffin feed, dehydrogenation catalyst, alkylation method etc. are exemplary in nature and the invention is not limited thereto. Since details of the equipment design and material management can take place according to known rules and are not important for understanding the subject matter of the invention, a schematic * Block diagram sufficient.

According to the flow diagram, an essentially pure normal paraffin stream occurs, in this case 99 percent by weight of n-tetradecane existing, enter the process through line 1. It is> mixed with a terradecane recycle stream passing through conduit 14 flows in. The resulting combined paraffin stream continues through line 1 into a dehydrogenation zone 2. The dehydrogenation zone 2 also becomes a hydrogen recycle stream fed through line 5, which consists of essentially pure hydrogen consists. The amount should be about 1 to 20 moles of hydrogen per mole of the paraffin flowing into the dehydrogenation zone 2, preferably about 5 to. 15 mol of hydrogen per> mol of n-paraffin.

In some cases it is advantageous to use a diluent, such as water, steam, methane, carbon dioxide, benzene or the like. In one or more of the in the dehydrogenation zone

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Provide flowing currents to control the temperature bal the implementation to control / the partial pressure of one or more to adapt the supplied reaction taker or the activity of the catalyst used. A preferred mode of operation in conjunction with that discussed above The preferred dehydrogenation catalyst consists, for example, in at least part of the hydrogen stream fed in the introduction into the dehydration zone 2 to saturate with water.

The dehydrogenation zone 2 contains a fixed bed of the dehydrogenation catalyst, in the present case the preferred catalyst described with 0.75 percent by weight of platinum and 0.1 percent by weight of lithium in combination with an aluminum oxide deposit material in the form of beads with a diameter of 1.6 mm, as well as 0.1 3 atoms of arsenic per atom of platinum. The hydrogen stream and the n-paraffin stream should be mixed with one another before entering the dehydrogenation zone. Both streams are heated by means not shown Heizeinrichtungsn to the desired transformation temperature for the preferred dehydrogenation catalyst in the range of about 399-593 ⁰ C (750 ~ HOO ⁰ F) and preferably about 427-538 ° C - is (800 IQOO ⁰ F) . The pressure in the dehydration zone 2 is maintained in the range of about 1.7 to 7.8 atm (10-100 psig), with most results being achieved in the range of about 2 to 3.7 atm (15 paig). The hourly space flow rate of the liquid in the dehydrogenation zone, based on the combined paraffin flow, is about 10 to 40 hours,

In the dehydrogenation zone 2, the supplied n-paraffins are selectively converted into n-mbnoolofins with the same number of carbon atoms. Although catalysts of the preferred type bring about this conversion with selectivities as high as 9S to '} & % , at the same time a gs-

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A small amount of by-products is generated. In the case of a delivery from n-tetradecane is the liawpt product n-tetradecsn, the By-products typically consist of conjugated C .. dienes, C .. isomers, naphthenes, aromatics, paraffins and olefins lower molecular weight.

A mixture of hydrogen and hydrocarbons is withdrawn from the dehydrogenation zone 2 through line 3 and passed through a condensing means, not shown, in which the temperature of the mixture is lowered to about 38 ° C (10O ⁰ F). The resulting cooled mixture is then introduced into a Tronnzone 4, in which a hydrogen-rich gas phase separates from a hydrocarbon-rich liquid phase. The hydrogen-rich gas phase is withdrawn from the transfer zone 1 through line 5 and returned via a compressor (not shown) in order to supply the hydrogen for the dehydrogenation zone 2. Excess hydrogen generated in the dehydrogenation reaction is withdrawn through line 15 during operation and the pressure Ln of the dehydrogenation chamber 2 is regulated and kept constant as a result. Conversely, the line 15 can be used during the start-up of the system to introduce hydrogen into the hydrogen cycle,

The hydrocarbon-rich liquid phase becomes withdrawn from the prenrone i and through line 6 in an alky-

ι *

lierungszoiu * 7 headed. In general, it is convenient to use this Stream prior to introduction into the alkylation zone 7 of a treatment to remove water from this stream if water is added to the feed for dehydration scene 2 and for removing hydrocarbons more easily j la C.. caused by minor cracking of C '. hydrocarbons can be generated in the dehydration zone 2 to un ~ t & r throws.

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Further, Cuir alkylation 7 is supplied to a monocyclic © aromatic compound _f which is introduced through line 13 to the process "A portion of the Alkyllerungszone-7 supplied Aromatenstroms consists of a recycle stream, which flows through line 12 and whose origin will be explained below. In general, any alkylatable monocyclic aromatic compound can be used so long as it can be separated from the n-paraffin stream by fractional distillation. Typical examples are benzene, toluene, xylene, ethylbenzene, methylethylbenzene, diethylbenzene. Phenol, non-nitrobenzene and the like. Benzene is preferably used as the inor.ocyclic aromatic compound.

In the alkylation zone 7, the aromatic compound and the hydrocarbon-rich liquid phase are eliminated the separation zone 4 ir. with an alkylation catalyst, preferably Hydrogen fluoride, brought into contact. The feed streams can be introduced at the same time or in a mixture with one another or it can be the aromatic compound with the alkylation catalyst brought into contact and then fed the hydrocarbon-rich stream. The molar ratio from aromatic compound to the monoolefin contained in the hydrocarbon stream is generally above equimolecular Maintained ratios, preferably in the range of about 2: 1 up to about 30: 1 to avoid polyalkylation of the aromatic compound and to keep polymerization of the olefin as low as possible *

In the alkylation zone 7, the reactants During a reaction period of about 5 to 100 minutes kept in contact with the alkylation catalyst, the the contact time used in particular depends on various factors, such as the type of reaction participants, the branch of the kata- *; lysators, the temperature, etc., from »Die Temperatur'in der Alky-.,

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lierungszone is in the range of about -18 to 93 C (east to 2OO ° F), and preferably about 21 to 66 ° C (70 to 150 ⁰ F). In general, a pressure is applied which is sufficient to maintain the catalyst and reactants in the liquid phase.

After the alkylation, a hydrocarbon mixture, which the alkylation products together with, is fed includes unreacted hydrocarbons, withdrawn through line 8 and a fraction: ionizer 9 fed. If, as preferred, the alkylation catalyst consists of hydrogen fluoride, the effluent from the alkylation zone 7 will be first passed into a separation zone, in which an acid phase of a hydrocarbon phase is separated. The hydrocarbon phase is then passed into a stripping column in which it is freed from entrained hydrogen fluoride. The resulting hydrogen fluoride-free hydrocarbon phase is then fed into the fractionation device 9.

The fractionation device 9 may comprise any suitable train of fractionation columns designed to separate the fed hydrocarbon mixture into a fraction rich in monocyclic aromatics, an n-paraffin fraction, an aryl-substituted η-paraffins fraction and a heavy alkylate fraction. Preferably around. the device holds three fractionating columns, the first of which is designed to separate monocyclic aromatics from the hydrocarbon mixture fed in. If, as is preferred, benzene is alkylated, this column _i serves to separate off excess benzene from the hydrocarbon mixture coming from the alkylation zone 7. The recovered benzene-rich fraction is conveniently returned to the alkylation zone through line 12. Diο soil fractions from this

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Benzene column flow through a treatment stage, not shown, in which alkyl fluorides are removed, for example by treatment with aluminum oxide, pie-treated bottoms from the benzene column are then introduced into an n-paraffin column from which an n-paraffin fraction, in the present case one mainly from C. Paraffins, which is obtained as an overhead product; this is returned to the dehydrogenation zone 2 through line IA. The bottom fractions from the paraffin column are drawn into a detergent alkoxide column, from which the detergent alkoxide produced as product is withdrawn in the form of the overhead product through line 10; a small amount of a heavy alkylate, usually comprising diphenylalkanes, bialkylindanes, etc., is withdrawn through line 11 as bottoms. The formation of this heavy alkylate is primarily due to the dienes formed as a by-product in dehydrogenation zone 2 and an alkylation of one mole of benzene

two moles of n-C, mono-olefins » 14 ·

If the η-paraffin returned to the dehydrogenation zone 2 contains aryl-substituted η-paraffins even in amounts which are to be regarded as insignificant from normal viewpoints, excessive deactivation of the dehydrogenation catalyst occurs. In particular, the following applies: Excessive catalyst deactivation occurs when the amount of aryl-substituted η-paraffins in this recycle stream exceeds such an amount that the combined n-paraffin feed fed to the dehydrogenation zone has more than about oil percent aryl-substituted η -Paraffins contains »Accordingly, the aryl paraffin content of the combined n-paraffin feed for the dehydrogenation zone.2 is kept below 0.1 percent by weight. Since in the technical implementation of the process, the ratio of return material to fresh embankment is normally in the range from about 4: 1 to about 9 s 1? can en the amount ^;

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aryl-substituted η-paraffin in the recycle stream is the limit of 0.1%, because the fresh load is usually free from these harmful compounds. To one to ensure safe and stable operation, so the low Fluctuations in the fractionation system do not have a critical impact, but the recycle stream is expedient at around kept to the limit of 0.1% or below, so that on everyone Case less than 0.1 weight percent aryl parafins in the total feed to the dehydrogenation zone is ensured.

In principle, in the n-paraffin recycle stream present ary! substituted n-para-ffins by any known measures are removed, but in practice it is best and simplest to check the operating conditions in the Separation zone, in which the recycle paraffins are separated from the alkylate, to be regulated accordingly. As with technical implementation this separation is normally done by fractional distillation, the amount of aryl-substituted η-paraffins that endkylat overhead in the separation of the n-paraffins from the aryl paraffins. Mix with the n-paraffin recycle stream is discharged, easily in a properly designed fractionation column by correct adaptation of either the Control the temperature of the reheater or the ratio of reflux to charge or both parameters at the same time, i.e. by simple ones known per se for the operation of a column Measures. For example, in a technical operational implementation when an aryl paraffin content of 0.1% is exceeded by increasing the reflux / feed ratio from 0.25: 1 to "0.5: 1 the aryl paraffin content is significantly below 0.1% reduced. Similarly, lowering the temperature of the reheater can produce the same result be achieved.

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The following examples illustrate a typical technical management. That Input material consists of a Ci ^ -G- ^

with an initial temperature of 19 ° C (-§7'3 ° F) and a final boiling point of 225 ° C (437 ° F), the 6/4 percent by weight of n-decane, 41.6 percent by weight of n-decane, 41 , 2 percent by weight of n-decane dodecane, 8.7 weight percent n-Trideeän and Q ₁ contains 4 weight percent of n-tetradecane * the thus Eihsäfezmäterial consists of 98.3 weight percent ATIS ri-Paraffihehi the results of the analysis show irtvassenspektrometrischeu "that the remaining constituents primarily from monocyelischeri Paraffins and dicyclic paraffins with lower amounts of aromatics exist «Furthermore, this input material contains 0.1 parts per million by weight of sulfur and 4.3 parts by weight per million of nitrogen»

The catalyst used in the dehydrogenation zone 2 is a composition of aluminum oxide, platinum, lithium and arsenic. It was made according to the procedure of US Pat. No. 3,291,755. According to chemical analysis, it contains 0.76 percent by weight of platinum _? 0.14 percent by weight arsenic and G, 495 percent by weight lithium, each calculated as elements. The catalyst is in the dehydration zone in the form of a solid consisting of spheres 1.6 mm in diameter »

In the alkylation zone 7, a solution of essentially anhydrous 95 percent by weight is used as a catalyst Used hydrofluoric acid.

The feed enters the process through line 1 and is exited with a recycle paraffin stream of the line 14 in a ratio of δ. ¥ oil parts of the return route each part fresh. Material mixed, The resulting mixture was 0.08 percent aryl-substituted Contains η-paraffins, is with a hydrogen recycle stream

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combined in such amounts that about 10 moles of H_ per mole of hydrocarbons are present in a mixture. The combined stream is in a heater to a temperature in the range heated from 454 to 520 ° C (850-950 ° F), the respectively present temperature within this range is slowly increased in order to constantly achieve a conversion of IO percent by weight of the η-paraffins entering the dehydration zone 2. The resulting heated mixture of hydrocarbons and hydrogen is used in the fixed bed of the dehydrogenation catalyst containing dehydrogenation zone 2 at a feed rate corresponding to an hourly space flow rate of the liquid of 30 h, based on the supplied Total mixture, introduced. The dehydration zone 2 becomes operated at 3.4 atm (35 psig) pressure.

The total outflow from dehydration zone 2 withdrawn through line 3, cooled to 27 ° C (80 ° F) and introduced into the separation zone 4. A hydrogen rich gas phase is removed from the separation zone 4 through line 5 and part of it becomes the dehydrogenation zone via a compressor 2 returned. The liquid hydrocarbon phase becomes withdrawn from the separation zone 4 through line 6, dried and by distillation of cracked products free tv and then Feeded into the alkylation zone 7.

In the alkylation zone 7, the liquid hydrocarbon phase is mixed. This enters the alkylation zone 7 through line 13 in an amount of about 10 moles of benzene per mole of n-moncolefin. The resulting hydrocarbon mixture is then mixed with hydrogen-free hydrogen fluoride in a ratio of 2 parts by volume of HF per part by volume of hydrocarbon mixture. The alkylation zone 7 is at a temperature of 38 ⁰ C (100 ⁰ F), a pressure of 18 atm (250 psig)

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and a residence time of about 20 minutes. The alkylation zone 7 is equipped with a cooling device to remove the heat from the exothermic reaction that is taking place.

The outflow from the alkylation zone flows into a separation zone, not shown in the drawing, in which an acid phase separates from a hydrocarbon phase. The acid phase is returned to the alkylation zone 7, with accumulated acid sludge being removed periodically. The hydrocarbon phase is then introduced into the fractionation device 9 through line 8. In the fractionation device 9, unconverted benzene is first separated off as an overhead product from the supplied hydrocarbon mixture. The separated benzene fraction is returned to the alkylation zone through line 12. The bottom portions of the benzene column are passed to an alumina treatment zone in which alkyl fluorides are removed. The resulting alkyl fluoride-free hydrocarbon mixture is further separated into a top-pot fraction comprising n-paraffins, which contains 0.1 percent by weight of aryl-substituted paraffins and is recycled through line 14 to dehydrogenation zone 2, a fraction consisting of phenyl-substituted η-paraffins, which is passed through line 10 withdrawn ¹ x and recovered and a heavy alkylate fraction exiting the process through line 11.

example

The example below illustrates the

Importance of a reduction, if not complete elimination, the amount of type aryl-substituted η-paraffin that is included in the catalytic dehydrogenation zone arrives. In this example two separate, apart from the content of aryl-substituted η-paraffins completely identical operations, hereinafter referred to as A

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Jt *

and H denotes, carried out, in both cases at a reactor outlet pressure of 3 atm (30 psig), a sturdy space *? liquid flow rate of 32.0 hours, a hydrogen / total hydrocarbon feed ratio of 8: 1 and a water content in the hydrocarbon feed of 20OO parts by weight per million The hydrocarbon feed for operation A was free of aryl-substituted paraffins and consisted of 98.5 percent by weight of C _1Q -C. "normal paraffins. For Run B, 0.5 weight percent aryl-substituted paraffins having 16 to 21 carbon atoms per molecule were added to the feed used in Run A. In both runs, the hydrocarbon feed was processed at different reactor inlet temperatures, each adjusted in the same way. The reactor effluent was cooled and the resulting liquid product was analyzed, the amount of n-oils in the reactor effluent, in percent by weight, being used as an indicator of the catalyst activity.

The results are compiled in the table below: <- '

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Operating
section Operational
zei-trauni,
Hours since
Beginning 1 . 4-8 ■■■ "· 2 8-12 3 12-16 Means of
sections Operate ~
1-3 5 20-26 9 44-50. 13th 68-74 17th 92-98 21 116-122 26th 146-152

Temp.

n-olefins in the reactor from flu3, weight -.- 1

Means of operating sections 5-26

158-164 172-176 182-188

Means of operating sections 28-32

194-200 212-218 218-223 242-243

460

465

470

475

Operational
run A Operational
run B 7.1 7.2 7.3 7.2 7.2 7.4

Mean of Betxitabs Sections 34-42 7.2

8.0 7.3 7.5 8.0 7.9 8.1

7.8

8.9

9.1

9.0

• 9.3 9.4

9.5 9, 4

7.3

8.1

.7.9

7.4

7.3

7.2

7.0

7.5

7.5

. 7.3

7.4

7.4 8.4

3.0 7.9

8.1

s / 1

The harmful effects of even very small amounts of aryl paraffins can be seen from the values listed in the table clearly shows the activity of the dehydrogenation catalyst. For example, after 248 hours, i.e. about 10 Days * the catalyst activity in run A, i.e. without Aryl paraffins, over 16% higher than the catalyst activity in run B, i.e. with 0.5% aryl paraffins. When approaching

«Taking the mean of operating sections 34-42 results an even higher improvement in activity of over 20%. Within of the first 100 hours, i.e. about 4 days, are considerable * observed shifts in activity.

Similar results obtained when operating with lower amounts of aryl paraffins in the feed show that for a given operation from procedural and economic points of view the amount of aryl substituted η-paraffins in the total feed to the dehydrogenation zone below about 0/1 Weight percent must be kept. These harmful aryl paraffins are the aryl paraffins * # that run through Alkylation with monoolefins of 9 to 20 carbon atoms per molecule are formed and accordingly when using benzene · as aromatic compound 15 to 26 carbon atoms «in the molecule exhibit.

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Claims (9)

Paten t claims i.) Process for the preparation of aryl-substituted NormaTparäffinen, where (a) an n-paraffin and hydrogen over a dehydrogenation catalyst in a dehydrogenation zone to form an n-monoolefin a carbon number equal to that of the paraffin used, present in a mixture with unreacted η-paraffin, implemented, (b) the n-monoolefin / n-paraffin mixture and a mohocyclic one aromatic compound on an alkylation catalyst in an alkylation zone to form an aryl substituent - - ierte n-paraffin, present in a mixture with unreacted monoeyclic aromatic compound and unreacted η-paraffin / are reacted, (c) da3 mixture of aryl-substituted η-paraffin, monocyclic aromatic compound and n-Pa raffin in one Separation zone with withdrawal of an n-paraffin recycle stream, 'which contains small amounts of aryl-substituted nr-paraffin, is separated, and. (d) the n-paraffin return form is returned to the dehydrogenation zone, characterized in that the operating conditions in the separation zone are known per se Measures regulates such that the amount of aryl-substituted η-paraffin in the n-Para.f in return flow is kept so low that the n-paraffin passed to the dehydrogenation zone Contains less than 0.1 percent by weight aryl-substituted n-paraffin. . , 309809/1153 BATH ORIGINAL 2. The method according to claim 1, characterized in that one is an n-paraffins or mixture of n-paraffins with about 9 to about 20 carbon atoms per .Molecule used. 3. The method according to claim 1 or 2, characterized in that the monocyclic aromatic compound Benzene or a mixture containing benzene is used. 4. The method according to claim 1 or 2, characterized in that that the monocyclic aromatic compound is benzene, toluene, a xylene, ethylbenzene, a methylethylbenzene, Phenol, a dietary hydrogen benzene; Mononitrobenzene or a mixture, at least one of these verl; contains indications. • 5. Method according to one of Addresses 1-4, thereby characterized in that a dehydrogenation catalyst is used which contains an aluminum oxide carrier, a component aua the group of alkali metals, alkaline earth metals and their compounds, a component from the group arsenic, bismuth, antimony, Sulfur, selenium, tellurium and their compounds, and a component from the group of platinum metals. 6. The method according to claim 5; characterized in that a dehydrogenation catalyst is used which Alumina, about 0.01 to »1.5 weight percent lithium, about 0.05 to 5 percent by weight platinum and about 0.01 to 1 percent by weight arsenic. 7. The method according to any one of claims ₍ 1 - 6, characterized in that benzene is used as the monocyclic aromatic compound and an η-paraffin or mixture of n-paraffins with 9 to 15 carbon atoms per molecule is used as the n-araffin. 309803/1153 ßAD ORIGINAL Process according to one of Claims 1-7, characterized in that a device for fractional distillation with a boiler and introduction of an overhead reflux stream is used as the separation zone and the temperature is used to control the amount of ary! Substituted η-paraffin in the n-paraffin recirculation stream of the reheater and / or regulates the reflux rate. 9. Method according to one of the claims 1 - 8, thereby characterized in that the alkylation catalyst used is hydrogen fluoride used. BATH ORIGINAL 309809/11 S3 Blank page