EP2155642A1

EP2155642A1 - Method for producing cyclopentanone

Info

Publication number: EP2155642A1
Application number: EP08760043A
Authority: EP
Inventors: Joaquim Henrique Teles; Mathieu Chabanas; Thomas Genger; Beatrice RÖßLER
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2007-06-04
Filing date: 2008-05-27
Publication date: 2010-02-24
Also published as: CN101687749A; WO2008148661A1; CA2688712A1; US20100179352A1

Abstract

The invention relates to a method for producing cyclopentanone. Said method comprises the step of reacting a mixture (G1), which contains at least cyclopentene, with a mixture (G2), which contains at least dinitrogen monoxide. The reaction is carried out in at least one reactor (R1) having channels with a diameter in the range of 0.1 mm to 50 mm, the reactor comprising at least two zones (Z1) and (Z2) having channels with different diameters and the diameters of the channels of zone (Z1) being smaller than the diameter of the channels of zone (Z2).

Description

Process for the preparation of cyclopentanone

description

The present invention relates to a process for preparing cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide, wherein the reaction in at least one reactor (R1) with channels having a diameter in the range of 0 , 1 mm to 50 mm, wherein the reactor has at least two zones (Z1) and (Z2) with channels of different diameters, and the diameter of the channels of the zone (Z1) is smaller than the diameter of the channels of the zone (Z2) ,

Processes for the preparation of cyclopentanone are basically known from the prior art. It is also known that cyclopentanone can be obtained by reacting cyclopentene with nitrous oxide. The production of cyclopentanone by oxidation of cyclopentene with N ₂ O is a highly selective reaction that is highly exothermic.

GB 649,680, for example, discloses the reaction of alkenes such as, for example, cyclohexene or cyclopentene with N ₂ O. However, in the examples of this document, the reaction of cyclopentene with N ₂ O is explicitly not described. Other, in the examples with N ₂ O reacted and unsubstituted olefins are used either as pure compounds or together with the solvent dimethylaniline. No. 2,636,898, which is equivalent to GB 649,680, likewise does not disclose the reaction of cyclopentene with N ₂ O in the examples. In these examples too, the unsubstituted olefins are reacted exclusively with N ₂ O in pure form without addition of a solvent. The reaction takes place at 300 ⁰ C and 500 atm.

FS Bridson-Jones et al. Describe in J. Chem. Soc., pp. 2999-3008 (1951) the reaction of olefins with N ₂ O, wherein, for example, cyclohexene is converted to cyclohexanone. Also in this case, the cyclohexene is used as such without adding, for example, an additional solvent. For example, the reaction of ethylene, acenaphthylene and methylenecyclobutane are described using either cyclohexane or decalin as the solvent.

Also KA Dubkov et al., React. Kinet. Catal. Lett., Vol. 77, no. 1, pp. 197-205 (2002) describe the reaction of pure, 99% cyclopentene with pure N ₂ O (pure, medical grade). In the recent scientific articles by GL Panov et al., "Non-Catalytic Liquid Phase Oxidation of Alkenes with Nitrous Oxides. *** 1. Oxidation of Cyclohexenes to Cyclohexanones", React. Kinet. Catal. Lett. Vol. 76, no. 2 (2002) pp. 401-405 and KA Dubkov et al., "Non-Catalytic Liquid Phase Oxidation of Alkenes with Nitrous Oxide." 2. "Oxidation of Cyclopentenes to Cyclopentanones", React. Kinet. Catal. Lett. Vol. 77, no. 1 (2002) pp. 197-205 also describe oxidations of olefinic compounds with dinitrogen monoxide. Also, a scientific article "Liquid Phase Oxidation of Alkenes with Nitrous Oxides to Carbonyl Compounds" by EV Starokon et al., Adv. Synth., Catal., 2004, 346, 268-274, contains a mechanistic study of the oxidation of alkenes with dinitrogen monoxide in the liquid phase ,

The synthesis of carbonyl compounds from alkenes with dinitrogen monoxide is also described in various international patent applications. Thus, WO 03/078370 discloses a process for the preparation of carbonyl compounds from aliphatic alkenes with dinitrogen monoxide. The reaction is carried out at temperatures in the range of 20 to 350 ⁰ C and pressures of 0.01 to 100 atm. WO 03/078374 discloses a corresponding process for the preparation of cyclohexanone. According to WO 03/078372 cyclic ketones are prepared with 4 to 5 carbon atoms. According to WO 03/078375, cyclic ketones are prepared from cyclic alkenes having 7 to 20 C atoms under these process conditions. WO 03/078371 discloses a process for the preparation of substituted ketones from substituted alkenes. WO 04/000777 discloses a process for reacting di- and polyalkenes with nitrous oxide to the corresponding carbonyl compounds.

DE 103 19 489.4 discloses a process for the preparation of cyclopentanone using nitrous oxide as the oxidizing agent.

WO 2006/032532 discloses a process for the preparation of cyclopentanone, starting from a mixture containing at most 95% by weight of cyclopentene. In addition to cyclopentene, the mixture used may contain further solvents, for example, further hydrocarbons are mentioned as mixture components. In this case, cyclopentanone is obtained by reaction with N ₂ O, either pure N ₂ O or a gas mixture containing N ₂ O is used in liquid or supercritical form. Preferably, the process disclosed therein is carried out in a batch reactor.

Since the reaction is first-order with respect to cyclopentene and N ₂ O, the reaction rate decreases rapidly with the conversion, which makes it difficult to achieve high conversions of both reactants. The reaction is highly exothermic, so that even in the plate heat exchangers known as efficient heat exchangers, heat dissipation is insufficient to avoid temperature spikes (so-called "hot spots") in a singular feed, which is all the more true for shell and tube heat exchangers.

Because of the high reaction temperature and the reaction rate, which is proportional in first approximation to the square of the density and the product of the concentration of the reactants, the reaction is carried out under elevated pressure and with the highest possible concentrations of starting materials in order to keep the reaction volume as low as possible. Since the reaction proceeds rapidly under these conditions and is highly exothermic, a (pressure-resistant) reactor is required, which allows high heat removal rates.

Although a dilution of the reactants leads to easier-to-handle heat production rates, but then inevitably to a much higher reactor volume and thus, due to the much higher to be moved streams to significantly larger systems and the associated higher costs.

In principle, it is known that, in particular for exothermic reactions, the reaction can be carried out in microreactors.

Microstructured or microstructured heat exchangers are well known in the art. For example, DD 246257 A1 already describes microappliances and methods for their production. The microapplications disclosed therein are produced from stacks of substrate platelets, the dimples incorporated in the individual substrate platelets varying in their dimensions, their shape and surface design.

WO 94/21372 also discloses reactors constructed of different layers and containing microstructured channels. Such devices can be used for chemical reactions.

WO 01/54806 discloses a reactor with a heat exchanger. In this case, the heat exchanger is formed from a plurality of superimposed metal plates, each having channels in which the heat exchanging agent can flow.

EP 0 212 878 A1 also discloses heat exchangers constructed from individual plates, the individual plates each having microstructured channels. The channels have according to EP 0 212 878 A1 a radius in the range of 0.2 to 1, 5 mm. WO 03/055585 discloses a chemical reactor. This reactor is formed from a stack of interconnected metal plates, each having recesses, so that reaction channels are formed.

WO 01/54805 relates to reactors having microstructures which are in spiral form in the reactor. WO 01/54804 also discloses heat exchangers which are built up from individual plates with microstructures, it being likewise disclosed that the heat exchangers disclosed there can also be used as chemical reactors.

WO 2004/099696 discloses plate heat exchangers. The individual plates initially have branching zones, microstructured zones and in turn a zone in which the individual streams are brought together.

DE 10036602 A1 discloses a microreactor for reactions between gases and liquids. The microreactors disclosed therein are suitable for carrying out chemical reactions between a reactant in fluid form and a reactant in the gaseous state, if appropriate in the presence of a solid catalyst. The chemical process management takes place in spaces that are formed by two or more, essentially plane-parallel plates or layers.

Also known from the prior art are chemical processes that are carried out in such microstructured reactors. Thus, EP 1 586 372 A1 discloses an alkoxylation in microstructured capillary reactors. There is disclosed a process and apparatus for the preparation of polyether alcohols by the alkoxylation of alcohols. The process is carried out in a microstructured reactor in the liquid phase. The individual channels of the reactor, which for example have a diameter of less than 2 mm, are cooled by means of a cooling medium or heated by means of a heating medium.

Starting from this prior art, an object of the present invention was to provide a process for the preparation of cyclopentanone, in which the starting materials can be reacted in high space-time yield and with good conversions.

Another object of the present invention was to provide a process for the preparation of cyclopentanone, in which the starting materials in high space-time Yield and good conversions can be implemented while minimizing the reactor cost.

Another object of the present invention was to provide a process for the preparation of cyclopentanone, in which the starting materials can be reacted in high space-time yield and with good conversions and which ensures a secure process.

According to the invention, this object is achieved by a process for the preparation of cyclopentanone comprising the reaction of a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide, wherein the reaction in at least one reactor (R1) with channels having a diameter in the range from 0.1 mm to 50 mm, the reactor having at least two zones (Z1) and (Z2) with channels of different diameters, and the diameter of the channels of the zone (Z1) being smaller than the diameter of the channels of the zone ( Z2).

According to the invention, the mixture (G1) contains at least cyclopentene. According to the invention, the mixture (G2) contains at least dinitrogen monoxide. The mixtures (G1) and (G2) are reacted with one another according to the process of the invention in gaseous or liquid or supercritical form. Preferably, the mixtures (G1) and (G2) are reacted according to the invention in supercritical form.

The reactor (R1) with channels having a diameter in the range of 0.1 mm to 50 mm can be used according to the invention alone or as a main reactor in combination with other reactors. It is possible for the reactor (R1) to be combined with a conventional reactor, for example a tubular reactor or a tube bundle reactor or another reactor with channels, in particular with a diameter in the range from 0.1 mm to 50 mm. It is possible according to the invention to operate the various reactors in series or in parallel or a combination of both.

The reactor (R1) according to the invention has channels with a diameter in the range of 0.1 mm to 50 mm. The process according to the invention is carried out in such a way that the reaction of the mixtures (G1) and (G2) takes place in the channels. The channels according to the invention make up the reaction volume of the reactor (R1).

The diameter of the channels through which the reactants flow may be substantially equal within a zone and is in the range of 0.1 mm to 50 mm. In a particular embodiment of the method, the channels are semicircular and have a radius between 0.05 and 25 mm.

According to the invention, the diameter of the channels within a zone is essentially the same. In this case, the individual channels can be arranged in parallel or have other geometric arrangements.

The reactor (R1) may for example consist of a stack of diffusion-welded metal plates into which recesses have been incorporated by a suitable method. This type of construction is known in principle from the prior art, for example from EP 0212878 A1 or WO 2004/099696.

The reactor (R1) can also have, for example, a device for heat exchange. For example, a microreactor constructed from plates can have layers in which a heating or cooling medium flows.

The production of the channels can take place, for example, in a multi-stage process in which the capillary structure in the form of channel shares or Nutenscharen is produced in individual plates in a first step by milling, etching, stamping or similar processes and then, for example by diffusion bonding or soldering Connection of the plates takes place. Each individual channel is thereby delimited from adjacent channels. Different zones with channels of different diameters can in principle be produced by combining plates with recesses of different diameters.

The mixing of the mixtures (G1) and (G2) can take place both outside and inside the reactor. When mixing outside the reactor, a suitable mixing element is connected upstream of the reactor. Preferably, however, the mixing of the reactants takes place in the reactor, preferably in the channels.

It is particularly preferred according to the invention, the mixture (G1) in a plate in channels to lead, which branch and thereby narrow to a diameter of 0.1 mm to 50 mm, and the mixture (G2) on the same plate or a other plate in separate channels, which also branch and narrow to a diameter of 0.1 to 50 mm, before the mixtures (G1) and (G2) are brought into contact with each other. For contacting the mixtures (G1) and (G2), it is possible, for example, to combine the streams from in each case two adjacent plates. For this purpose, openings can be located in all channels of one plate, through which the currents from the channels of the other, adjacent plates te be led. Thus, the streams are combined from one channel each for mixture (G1) and one channel for mixture (G2).

According to the invention, the reactor (R1) can have an entry zone. Such an entry zone consists for example of at least one plate and carries the two separate accesses for mixture (G1) and (G2). The two inlet channels are first branched and the mixtures (G1) and (G2) are preferably mixed together only when the channels have a cross-sectional area which is comparable to the cross-sectional area of the channels in the zone (Z1).

At the mixing points, the mixtures (G1) and (G2) are passed, for example, through vertical bores into the first product plate of the reaction zone. In one possible embodiment of the entry zone, the channels for the mixture (G1) and the mixture (G2) are divided into different plates.

For example, mixture (G1) in the first plate is split and passed through vertical channels into the next plate, where it joins with the split mixture (G2) to produce a mixed stream, which in turn can be passed through vertical channels into another plate , According to the invention, it is also possible that there are further plates with channels for a cooling medium between the individual plates.

As a result of the reaction procedure according to the invention, the process according to the invention is particularly advantageous in terms of safety since particularly intensive cooling is possible by the reaction regime in the reactor (R1).

At the reactor outlet, in principle, the channels can be combined to form wider channels. The channels of the last product plate can for example be combined to form an outlet line. According to the invention it is also possible to replace this exit zone by a hood, for example, when the conversion of cyclopentene and nitrous oxide is at least 90%.

Therefore, according to another embodiment, the present invention also relates to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels having a diameter in the range from 0.1 mm to 50 mm, blending the mixtures (G1) and (G2) in the reactor in the channels. The merging of the mixtures (G1) and (G2) according to the invention can for example be such that the reaction mixture enters immediately behind the mixing points in a wall-cooled portion of the plate, in which the known advantageous intensive heat transfer condition can be used in microstructures and a leadership of the reaction with negligible temperature increases is possible. The cooling channels in the cooling plates can be mounted parallel or perpendicular to the flow direction of the reaction medium. Thus, a DC, counter and cross-flow of the cooling medium is possible.

The method according to the invention thus makes it possible to limit or reduce hot spots, ie local overheating. According to the invention, it is particularly preferred to carry out the method such that in each case at the beginning of a zone, a hot spot occurs in a permitted range, that is, for example, a temperature increase in the range of 10 ⁰ C occurs. According to the invention, the temperature in the reactor at a given point in the reactor up to 350 ⁰ C, preferably at most 340 ° C, in particular up to 320 ⁰ C, more preferably at most 310 ° C, more preferably at most 300 ° C.

A further advantage of the method according to the invention is that an increase in scale (scale-up), for example, by modular guidance of the number of channels in microstructured reactors or the increase in the number of microstructured reactors can be easily carried out. Thus, the production capacity can be increased easily and without risk.

The microstructured reactor (R1) used according to the invention can therefore be designed in particular for carrying out continuous processes in the fluid phase.

The inventively used reactor (R1) has at least two zones (Z1) and (Z2) with channels of different diameters and the diameter of the channels of the zone (Z1) is smaller than the diameter of the channels of the zone (Z2). Accordingly, the diameter of the channels increases from zone (Z1) to zone (Z2), it being possible according to the invention to set the reaction conditions such that a hot spot in the permitted range occurs at the beginning of each zone. Thus, according to the invention, it is possible to control the course of the reaction via the reactor (R1) in such a way that the reaction volume is optimally utilized. Compared to a reactor with essentially constant diameter of the channels, in the reactor (R1) used according to the invention, the reactor volume is better utilized by comparatively more reaction volume due to increasing diameter of the channels. The reactor (R1) used according to the invention has at least two zones (Z1) and (Z2) with channels having a diameter in the range from 0.1 mm to 50 mm. In addition, the reactor (R1) may have other zones, for example further zones with channels having a diameter in the range of 0.1 mm to 50 mm or zones in which the mixtures (G1) or (G2) or (G1) and (G2) are introduced into the reactor and have the channels that branch and whose diameter narrows to a diameter in the range of the diameter of the channels in the zones (Z1) and (Z2).

For example, according to the invention, the reactor (R1) can also have a zone in which the mixtures (G1) and (G2) are brought into contact or a zone, for example an exit zone, in which the channels are brought together and widened.

One of the advantages of the process according to the invention is that the reaction of cyclopentene and dinitrogen monoxide with a high space-time yield can be carried out without safety concerns. The method also makes it possible to design the microreactor as cost-saving as possible because of the zones with channels with different diameter, the process control can be that at the beginning of each zone again a temperature increase may occur, the inventive maximum temperature in the reactor on a certain point is not exceeded. Due to the highly efficient heat dissipation, it is possible to operate without diluting additives.

The process according to the invention allows a conversion of mixture (G1) and mixture (G2) with a conversion based on dinitrogen monoxide of greater than or equal to 80%, in particular greater than or equal to 85%, particularly preferably greater than or equal to 95%. According to the invention, the conversion based on cyclopentene is greater than or equal to 50%, in particular greater than or equal to 55%, particularly preferably greater than or equal to 60%.

The upper limit of the conversions, both based on cyclopentene and based on dinitrogen monoxide, is generally 90%, preferably 92%, in particular 95%, more preferably 98%, and most preferably 99%.

The molar ratio between N ₂ O in the mixture (G2) and cyclopentene in the mixture (G1) is set according to the invention so that the ratio is greater than 0.5, preferably greater than 0.6. The reactor (R1) used according to the invention has at least two zones (Z1) and (Z2) with channels having a diameter in the range from 0.1 mm to 50 mm. According to the invention, the reactor (R1) can also have more zones with channels having a diameter in the range from 0.1 mm to 50 mm, for example 3, 4 or 5 zones, particularly preferably 3 zones (Z1), (Z2) and ( Z3), wherein the zones each have channels with a diameter in the range of 0.1 mm to 50 mm. According to the invention, the diameter of the channels in each zone is smaller than in the following zone.

According to the invention, the proportion of the reaction volume formed by the channels of the first zone (Z1) in the total reaction volume in the reactor is 1 to 60%, in particular 5 to 55%, more preferably 10 to 50%, particularly preferably 15 to 45%, for example 20 %, 25%, 30% 35% or 40%.

Therefore, according to a further embodiment, the present invention also relates to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels having a diameter in the range from 0.1 mm to 50 mm, wherein the reactor (R1) has at least three zones (Z1), (Z2) and (Z3) with channels having a diameter in the range of 0.1 mm to 50 mm, and the Diameter of the channels of the zone (Z1) is smaller than the diameter of the channels of the zone (Z2) and the diameter of the channels of the zone (Z2) is smaller than the diameter of the channels of the zone (Z3).

According to the invention, the diameter of the channels in the zones (Z1), (Z2) and (Z3) is in the range of 0.1 mm to 50 mm.

For example, the diameter of the channels in the zone (Z1) is in the range of 0.5 mm to 2 mm, preferably in the range of 0.7 mm to 1, 8 mm, in particular in the range of 0.9 mm to 1, 5 mm , For example, the diameter of the channels in the zone (Z2) is in the range of 2.5 mm to 6 mm, preferably in the range of 3 mm to 5.5 mm, in particular in the range of 3.5 mm to 5 mm. For example, the diameter of the channels in the zone (Z3) is in the range of 6.5 mm to 10 mm, preferably in the range of 7 mm to 9.5 mm, in particular in the range of 7.5 mm to 9 mm.

Therefore, according to another embodiment, the present invention also relates to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels having a diameter in the range from 0.1 mm to 50 mm, the diameter of the In the zone (Z1) is in the range of 0.5 mm to 2.0 mm, the diameter of the channels in the zone (Z2) is in the range of 2.5 mm to 6.0 mm and the diameter of the channels in the zone (Z3) is in the range of 6.5 mm to 10.0 mm.

According to the invention, a plurality of reactors, for example two reactors (R1) and (R2), with channels having a diameter in the range of 0.1 mm to 50 mm can also be used for the method, in particular those having zones with channels of different diameter. The reactors (R1) and (R2) used may have the same or a different number of zones. For example, reactor (R1) may have two zones (Z1) and (Z2) and the reactor (R2) may have three zones (Z1), (Z2) and (Z3). Both reactors (R1) and (R2) preferably have three zones (Z1), (Z2) and (Z3), it being possible for the diameter of the channels in the two reactors to vary in the range according to the invention.

Therefore, according to another embodiment, the present invention also relates to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels having a diameter in the range from 0.1 mm to 50 mm, the reaction being carried out in two parallel reactors (R1) and (R2) each having channels with a diameter in the range from 0.1 mm to 50 mm and the reactor (R1) and the reactor (R2) each have at least two zones (Z1) and (Z2) with channels of different diameters and the diameter of the channels of the zone (Z1) is in each case smaller than the diameter of the channels of the zone (Z2).

If a plurality of reactors (R1) and (R2) are used, they can be connected in parallel or serially, preferably in parallel, according to the invention. According to the invention, it is also possible to connect two reactors (R1) and (R2) in parallel with channels having a diameter in the range from 0.1 mm to 50 mm and to connect a further reactor, for example a tubular reactor or a tube bundle reactor, as a postreactor.

The reaction conditions for the process according to the invention can be varied within wide limits. Thus, the reaction is preferably carried out at a temperature of 200 to 350 ⁰ C, preferably at 230 to 340 ⁰ C, in particular at 250 to 320 ° C, particularly preferably at 270 to 300 ⁰ C, for example at 280 ° C, 285 ° C. , 290 ^o C or 295 ° C.

Preferably, the reaction is carried out at a pressure of 200 to 500 bar, preferably at 220 to 450 bar, in particular at 240 to 400 bar, particularly preferably at 260 to 350 bar, for example at 265 bar, 270 bar, 275 bar, 280 bar, 285 bar, 290 bar, 295 bar, 300 bar, 305 bar, 310 bar, 315 bar, 320 bar, 325 bar, 330 bar, 335 bar, 340 bar or 345 bar.

According to a preferred embodiment, the reaction is carried out in the temperature range between 270 and 300 ⁰ C and at a pressure of 260 to 350 bar, in particular 280 bar.

The reaction conditions are preferably selected such that the N ₂ O conversion is more than 80% and the cyclopentene conversion is more than 50%.

Therefore, according to a further embodiment, the present invention also relates to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels with a diameter in the range of 0.1 mm to 50 mm, wherein the reaction is carried out at a pressure of 200 to 500 bar and a temperature of 270 to 300 ⁰ C.

According to the invention, the mixture (G1) contains at least cyclopentene. The mixture (G1) preferably contains at least 90% by weight of cyclopentene, for example 90 to 99% by weight of cyclopentene, preferably 91 to 95% by weight of cyclopentene, in particular 92% by weight, 93% by weight or 94 Wt .-% cyclopentene.

Therefore, according to another embodiment, the present invention also relates to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels having a diameter in the range from 0.1 mm to 50 mm, the mixture (G1) containing at least 90% by weight of cyclopentene.

In principle, the mixture (G1) may contain any further compound in addition to cyclopentene. Also suitable are compounds which can also react with N ₂ O. Preference is given here to those compounds which, although they can in principle react with N ₂ O, are inert to N ₂ O at the reaction conditions chosen according to the invention. The term "inert" as used in the context of the present invention refers to compounds which either do not react with N ₂ O in the reaction conditions selected according to the invention or which react in a restricted manner in comparison with the reaction of cyclopentene with N ₂ O such that their reaction product with N ₂ O in the resulting mixture to a maximum of 5 wt. %, preferably at most 3 wt .-% and particularly preferably at most 2% by weight, in each case based on the total weight of the resulting mixture.

The content of secondary components in the mixture (G1) is for example less than 15 wt .-%, preferably less than 12 wt .-%, preferably less than 10 wt .-%, in particular less than 8 wt .-%, particularly preferably less than 5% by weight.

According to a further preferred embodiment of the process according to the invention, the mixture (G1) consists of at least 99% by weight, based on the total weight of the mixture (G1), of hydrocarbons. In addition to the hydrocarbons, the mixture (G1) may accordingly contain at most 1% by weight of at least one further compound, wherein inter alia at least one of the abovementioned inert preferred compounds other than hydrocarbons may be present at not more than 1% by weight , Other compounds may also contain at most 1% by weight, provided that they do not interfere with the reaction of cyclopentene with the mixture (G2).

The term "hydrocarbons" as used in the context of the present invention denotes compounds, each of which is an unsubstituted hydrocarbon and therefore consists only of the atoms C and H. More preferably, the mixture contains at most 0.5 wt .-%, more preferably at most 0.1 wt .-%, more preferably at most 0.01 wt .-% and most preferably at most 0.001 wt .-% more Links. Particular preference is given to mixtures (G1) which, in addition to hydrocarbons, do not contain any further compounds within the scope of the measurement accuracy of the particular analytical methods used in each case.

According to a preferred embodiment, the mixture (G1) is gaseous, liquid or supercritical, preferably supercritical, at the reaction conditions selected according to the invention.

Within the scope of a likewise preferred embodiment of the process according to the invention, a mixture (G1) is used which contains at least 90% by weight, preferably at least 95% by weight, in particular at least 99% by weight, of C ₅ hydrocarbons and hydrocarbons with more than 5 carbon atoms. In addition to cyclopentene, accordingly, at least one further C ₅ hydrocarbon or at least one hydrocarbon having more than 5 carbon atoms or a mixture of at least one further C ₅ hydrocarbon and at least one hydrocarbon having more than 5 carbon atoms can be present in (G1). Accordingly, the present invention also describes a process as described above which is characterized in that the mixture (G1) contains at least 99% by weight of C ₅ hydrocarbons and hydrocarbons with more than 5 carbon atoms.

Among others, particularly preferred hydrocarbons having more than 5 carbon atoms, the corresponding, already mentioned above in the context of inert compounds hydrocarbons are used.

According to the invention, mixtures (G1) are preferably those mixtures which are obtained in industrial processes. In the context of the present invention, mixtures are preferred which contain at least 95% by weight, more preferably at least 97% by weight and particularly preferably at least 99% by weight, of C ₅ , C ₆ and C ₇ . Hydrocarbons exist.

Accordingly, the present invention also relates to a process as described above, which is characterized in that the mixture (G1) contains at least 99% by weight of C ₅ - and C ₆ - or C ₅ - and C ₇ - or C ₅ - and C ₆ and C ₇ hydrocarbons.

In the context of the present invention, the mixture (G1) in addition to cyclopentene either at least one further C ₅ hydrocarbon or at least one C ₆ hydrocarbon or at least one C ₇ hydrocarbon or a mixture of at least one other C ₅ hydrocarbon and at least one C ₆ hydrocarbon or a mixture of at least one further C ₅ - hydrocarbon and at least one C ₇ hydrocarbon or a mixture of at least one further C ₅ hydrocarbon and at least one C ₆ - hydrocarbon and at least one C ₇ hydrocarbon ,

In the context of a preferred embodiment of the process according to the invention, the mixture (G1) used is a hydrocarbon mixture which is obtained from a steam cracker or a refinery and contains cyclopentene. In this context, for example, C ₅ cuts from steam cracker plants are preferred which contain substantially only C ₅ and C ₆ hydrocarbons. Hydrocarbons having more than 6 carbon atoms are usually not included in the industrially occurring C ₅ sections, which in addition to cyclopentene, for example, 2-butene, isopentane, 1-pentene, 2-methylbutene-1, trans-2-pentene, n-pentane, cis 2-pentene, 2-methylbutene-2, cyclopentane, 2,2-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane and benzene. In general, a C _{5 cut} from a steam converter plant contains cyclopentene in the range from 5 to 60% by weight, and preferably in the range from 15 to 50% by weight. Such mixtures are advantageously further processed. nigt before they are used as a mixture (G1) in the process according to the invention.

Therefore, the present invention also describes a process as described above which is characterized in that the mixture (G1) contains at least 99% by weight of a mixture of C ₅ and C ₆ hydrocarbons.

According to the invention, this mixture of essentially C ₅ and C ₆ hydrocarbons, which is preferably obtained as C _{5 cut} from a steam cracker plant, can be used as such. Preferably, the mixture of substantially C ₅ - and C ₆ -KoIi is subjected to a cleaning before the reaction according to the invention, in which again preferably lower boiling compounds are separated compared to cyclopentene. While all conceivable methods can be used, the distillative separation of the mixture is preferred.

In the context of the present invention, preference is given here to mixtures (G1) which contain at most 10% by weight of C ₅ and / or C ₆ hydrocarbons which boil more readily than cyclopentene. If, in the mixture to be purified, optionally at least one C ₄ hydrocarbon is also present, preference is given to obtaining mixtures (G1) containing not more than 25% by weight of C ₄ and / or C ₅ and by the preferred distillation or C ₆ hydrocarbons boil easier than cyclopentene. In the context of the present invention, particular preference is given to mixtures (G1) which contain not more than 15% by weight, more preferably not more than 10% by weight and more preferably not more than 5% by weight of C ₅ and / or or C ₆ hydrocarbons boil easier than cyclopentene. If, in the mixture to be purified, optionally at least one C ₄ hydrocarbon is also present, preference is given to obtaining mixtures (G1) containing not more than 5% by weight, more preferably not more than 3% by weight, and especially by the preferably used distillation preferably not more than 2% by weight of C ₄ and / or C ₅ and / or C ₆ hydrocarbons which boil more readily than cyclopentene.

The mixtures thus obtained generally contain cyclopentene in a range from 80 to 99.99% by weight, preferably in a range from 85 to 99% by weight and more preferably in a range from 90 to 95% by weight. , Such mixtures can be further purified or concentrated before they can be used according to the invention as a mixture (G1). In particular, the present invention therefore also relates to the use of a cyclic hydrocarbon mixture as starting material for the preparation of cyclopentanone, characterized in that the cyclopentene-containing hydrocarbon mixture either the C _{5 cut of} a steam cracker plant or obtained from the partial hydrogenation of cyclopentadiene and cyclopentene-containing mixture or a mixture of the C _{5 cut of} a steam cracker plant and the mixture obtained from the partial hydrogenation of cyclopentadiene and containing cyclopentene.

According to the invention, the mixture (G2) contains at least 70% by volume of dinitrogen monoxide, for example 70 to 100% by volume. The mixture (G2) preferably contains at least 75% by volume of dinitrogen monoxide, in particular at least 80% by volume, preferably at least 85% by volume. The mixture (G2) preferably contains from 75 to 99% by volume of dinitrogen monoxide, particularly preferably from 80 to 95% by vol., Particularly preferably from 82 to 90% by vol., For example 83% by vol., 84 vol. %, 85 vol.%, 86 vol.%, 87 vol.%, 88 vol.% Or 89 vol.%.

Therefore, according to a further embodiment, the present invention also relates to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels with a diameter in the range of 0.1 mm to 50 mm, the mixture (G2) containing at least 70% by volume of dinitrogen monoxide.

The present invention also relates in a further embodiment to a process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide in at least one reactor (R1) with channels having a diameter in the range of 0.1 mm to 50 mm, the mixture (G2) containing 75 to 99 vol .-% nitrous oxide.

In principle, the mixture (G2) containing dinitrogen monoxide can originate from any source.

According to the invention, this mixture (G2) is preferably liquefied and then used in liquid form. In this case, nitrous oxide or the gas mixture containing dinitrogen monoxide can be liquefied by all methods known to the person skilled in the art, in particular by a suitable choice of the pressure and the temperature.

According to the invention, mixture (G2) can contain at least one further gas in addition to N ₂ O. Essentially, all gases are conceivable as long as they are guaranteed. tet is that the inventive reaction of cyclopentene with N ₂ O is possible. In particular, therefore, mixtures (G2) are preferred which contain at least one inert gas in addition to N ₂ O. The term "inert gas" as used in the context of the present invention refers to a gas which is inert under the reaction conditions with respect to the reaction of N ₂ O with cyclopentene and also with respect to N ₂ O. Examples of inert gases are nitrogen, carbon dioxide To name carbon monoxide, argon, methane, ethane and propane.

Likewise, in the mixture (G2) gases may also be present which do not behave as inert gases in the reaction of N ₂ O with cyclopentene. Such gases include NO _x or, for example, oxygen. The term "NO _x ", as understood in the context of the present invention, all compounds N ₃ Ob except N ₂ O, where a is 1 or 2 and b is a number from 1 to 6. Instead of the term ,, NO _x "is in the context of the present invention, the term" nitrogen oxides used ". in such a case, it is preferred to employ such mixtures (G2), the content of these gases than 0.5 Vol .-%, based on the total weight of Mixture (G2).

Accordingly, the present invention also relates to a process as described above, which is characterized in that the mixture (G2) contains at most 0.5% by volume of oxygen or at most 0.5% by volume of nitrogen oxides or at most both 0, 5% by volume of oxygen and 0.5% by volume of nitrogen oxides, in each case based on the total volume of the mixture (G2). A value of, for example, 0.5% by volume denotes a total content of all possible nitrogen oxides except N ₂ O of 0.5% by volume.

In principle, the composition of the mixtures in the context of the present invention can be determined in any manner known to the person skilled in the art. The composition of the mixture (G2) is preferably determined by gas chromatography in the context of the present invention. However, it can also be determined by means of UV spectroscopy, IR spectroscopy or wet-chemical.

According to the invention, the mixture (G2) is used in particular in liquid or supercritical form, preferably in supercritical form. In this case, it is possible according to the invention that the mixture (G2) is subjected to a treatment before liquefaction in order to reduce the concentration of inert and interfering compounds in the mixture (G2).

In particular, it is within the scope of the present invention possible to use mixtures (G2) which are obtained from industrial processes. Accordingly, should these mixtures (G2) contain more than 0.5% by volume of oxygen and / or nitrogen oxides, then these can generally be used in the process according to the invention. These mixtures (G2), as well as those mixtures (G2) of similar composition, which are not obtained from industrial processes, are preferably subjected to at least one purification step before use in the process according to the invention, in which the content of oxygen and / or nitrogen oxides at most 0.5% by volume.

A suitable within the context of the present invention gas mixture (G2) preferably contains 50 to 99.0 vol .-% nitrous oxide, 1 to 20 vol .-% carbon dioxide and 0 to 25 vol .-% of other gases. The stated vol .-% refer in each case to the entire gas mixture (G2). The sum of the individual components of the gas mixture (G2) gives 100 vol .-%.

Preferably, the gas mixture (G2) contains from 60 to 95% by volume of dinitrogen monoxide, in particular from 70 to 90% by volume, particularly preferably from 75 to 89% by volume of dinitrogen monoxide.

The gas mixture (G2) may further contain 1 to 20% by volume of carbon dioxide. Preferably, the gas mixture (G2) contains 5 to 15% by volume of carbon dioxide, in particular 6 to 14% by volume of carbon dioxide.

Preferably, the gas mixture (G2) 0 to 25 vol .-% further gases. The gas mixture (G2) may contain one or more further gases, the stated amount being based on the sum of the gases contained.

Suitable processes for the preparation of such a gas mixture are known per se to the person skilled in the art.

The residence time of the reaction mixture in the reactor (R1) or in the reactors (R1) and (R2) is generally in the range from 0.1 to 48 h, preferably in the range from 0.2 to 5 h and particularly preferably in the range of 0 , 3 to 2.5 h. It is conceivable not to keep the temperature or the pressure or both in the reactor constant, but to vary suitably within the limits specified above.

The cyclopentanone selectivities of the reaction with respect to cyclopentene are according to the invention, for example, in the range of 85 to 99.9%, preferably 90 to 99%, in particular 92 to 97%.

The mixture obtained by the process according to the invention and containing cyclopentanone can in principle be further processed in the form obtained. Inventions however, according to the invention, the resulting mixture may also be worked up in accordance with any suitable process for recovering the cyclopentanone. Particular preference is given according to the invention to distillative processes for working up.

The process according to the invention may in particular comprise a further separation stage which is carried out after the reaction in the reactor (R1) or the reaction in the reactors (R1) and (R2) or the post-reactors. The separation stage preferably comprises at least one distillation, but preferably at least one flash distillation, for example for the separation of N ₂ and unreacted N ₂ O, and a distillation. The distillation according to the invention can be carried out, for example, at a pressure of 2 to 6 bar, preferably 3 to 5 bar, in particular 4 bar and a bottom temperature of 150 to 250 ⁰ C, preferably 170 to 200 ⁰ C, for example 180 ° C.

According to the invention, at least two flash stages are preferably carried out, for example two, three or four. If, for example, two flash stages are performed, they are carried out in particular at different pressure and temperature. Thus, preferably, the first flash stage at a pressure of 15 to 30 bar, preferably 18 to 26 bar, in particular 20 to 23 bar and a bottom temperature of 100 to 200 ⁰ C, preferably 120 to 180 ° C, for example 140 to 160 ° C performed. The second flash stage is preferably at a pressure of 1 to 8 bar, preferably 2 to 6 bar, in particular 3, 4 or 5 bar and a bottom temperature of 50 to 150 ⁰ C, preferably 75 to 125 ° C, for example 85 to 105 ° C performed.

The separation stage according to the invention may comprise at least one flash vessel and one distillation column. After leaving the reactor (R1) or the reactors or after leaving the secondary reactor, the reactor discharge is preferably expanded and cooled to separate off formed N ₂ and unreacted N ₂ O as a gaseous stream. This gaseous stream can in principle be returned to the N ₂ O enrichment, but is preferably disposed of. Preferably, the stream is depressurized to a pressure slightly above the pressure in the distillation column. The liquid stream is then worked up in one or more distillation columns. Preferably, for example, unreacted cyclopentene is removed overhead and, according to the invention, can be recycled at least partially or completely to the reactor. If necessary, a portion of the stream may be discarded to optionally suppress the accumulation of minor components. These secondary components are preferably removed by distillation. In the bottom, cyclopentanone is preferably separated substantially. For example, cyclopentanone can be further purified by distillation. The distillation can be carried out according to methods known per se to those skilled in the art.

The reactor (R1) used for the process according to the invention is also suitable for other reactions which take place in the fluid phase, ie in the liquid or supercritical phase, where at least two reactants are reacted in the presence of a homogeneous catalyst or without catalyst and which are highly exothermic. In particular, such reactors are suitable for reactions in which the adiabatic temperature increase is above 100 ⁰ C.

Examples of such reactions are in particular the oxidation of olefins or alkynes with N ₂ O, the epoxidation of CC double bonds with H ₂ O ₂ or hydroperoxides, the oxidation of ketones with nitric acid or the addition of nucleophiles to epoxides, for example of water, Alcohols, ammonia, amines, hydroxylamines or hydrazines.

The invention will be explained in more detail below with reference to examples.

EXAMPLES

Example 1 (Comparative Example): Reaction in the tubular reactor

Example 1 was carried out in a reactor with flash and distillation stage downstream.

The reactor consists of a series of 16 individual tubes (outer diameter = 10 mm, wall thickness = 2 mm, inner diameter = 6 mm, length = 5.3 m) wound spirally (radius r = 125 mm, pitch P = 30 mm) , The reaction volume including connectors is 2510 ml in total.

The tube is provided with a double jacket (outer tube: outer diameter = 20 mm, wall thickness = 2 mm, annular gap width = 3 mm) through which a cooling liquid is pumped in cocurrent to dissipate the heat of reaction (Marlotherm SH from Sasol). The temperature of the incoming cooling medium is set to 280 ± 2 ° C with an external thermostat. Directly at the outlet of the reactor is a pressure maintenance, which keeps the pressure in the reactor constant at 280 bar. The fresh cyclopentene is metered into the reactor at 172.5 g / h. Cyclopentene originates from the distillation of a C _{5 cut of} a steam cracker and has the following composition (% by weight): cyclopentene (about 93.2%), cyclopentane (about 5.7%), 2-methyl-2-butene (about 1, 1%), 2,2-dimethylbutane (about 0.17%).

By mixing this stream with a cyclopentene recycle stream, a stream of the following composition is produced: cyclopentene (about 48.8%), cyclopentane (about 46.2%), 2-methyl-2-butene (about 3.1%). ), Acetone (about 2.0%), 2,2-dimethylbutane (about 0.96%). This stream is then metered to the reactor with a metering pump (flow rate: 1632 g / h).

As a further stream of liquid N ₂ O (content of N ₂ O> 99.5 vol .-%, Messrs. Messer Griesheim) is metered at about 99.2 g / h to the reactor. The molar ratio of cyclopentene to N ₂ O in the reactor feed is 0.192 mol / mol.

The cyclopentene conversion in the straight pass is 19.6% and the N ₂ O conversion is about 99.6%. The reactor discharge is relaxed after pressure maintenance in two steps with two at 1 1 bara and 1, 1 bara operated flash vessels to 1, 1 bara and cooled. The gaseous components are separated and in an aftercooler (operated at + 5 ° C) hydrocarbons contained therein are condensed out as completely as possible. The gas phase (about 64.5 g / h) has the following composition: N ₂ (96.4% by volume), N ₂ O (0.41% by volume), ethylene (0.28% by volume). ), Cyclopentene (0.37% by volume), cyclopentane (0.33% by volume), other C ₅ components (545 vppm).

The liquid phase obtained is separated in a distillation column (bubble-cap column with 5 column sections 106 cm × 50 mm, 10 plates each). The bottom product obtained is 187.7 g / h of a stream having the following composition (wt .-%): cyclopentanone (about 96.8%), cyclopentane (about 1, 3%), 4-pentenal (ca. 1.3%), isopropyl methyl ketone (about 0.8%), cyclopentene oxide (about 0.5%), cyclopentene dimers (about 0.5%), cyclopentene (about 0.03%).

From the top product, which contains 43.4% cyclopentene but no cyclopentanone, about 14.9 g / h are discharged to avoid the accumulation of minor components, in particular acetone and 2-methyl-2-butene. The remainder (about 1460 g / h) is returned as a cyclopentene recycle stream to the mixer with fresh C5.

After this procedure, the space-time yield is about 72.4 g cyclopentanone / liter reaction volume / hour. For each kg of cyclopentanone produced, about 8.2 kg of cyclopentene / cyclopentane mixture must be separated off and recycled for the most part. The energy required for the distillation is 0.73 kWh / kg of cyclopentanone. Example 2: Reaction in the microreactor

Example 2 was carried out analogously to Example 1, wherein the tubular reactor was replaced by a microreactor and in addition a post-reactor was used.

The reactor was manufactured by the company Heatric (Vessel title: Demonstration Mixer Reactor, Plant Item No .: E100, Year built: 2005, Client: BASF, Client PO No .: 1086229765/306 / D, Serial No .: H1016A, Type: PCR).

The main reactor consists of 48 316 / 316L stainless steel plates with 338 x 188 * 1, 9 mm in which semicircular channels were created and then diffusion welded into a single block. The finished reactor has the following dimensions: 338 x 188 x 91 mm. The two starting materials are fed through separate inlets and first divided in the entry zone (upper plate) and then mixed. The available reaction volume in this main reactor is about 194 ml distributed over 10 plates. In these plates there are two parallel product-carrying channels which are semicircular and have a radius of 1, 2 mm (cross-sectional area: 2.262 mm ² ). The channels are arranged in parallel on each plate and undercut 49 passages on each plate. The total length of each channel is thus about 45 m.

Coolant is pumped through the cooling circuit at a rate of approx. 16 l / min to dissipate the heat of reaction (Marlotherm SH from Sasol). The temperature of the incoming cooling medium is set to 280 ± 2 ⁰ C with an external thermostat. The secondary reactor used is two pipe coils connected in series, which are also operated at 280 ± 2 ° C. These coils have the same dimensions as those of the reactor used in Example 1. The total available reaction volume (including connecting pieces) is approx. 530 ml_. At the outlet of the last reactor is a pressure maintenance, which keeps the pressure in the reactor and post reactor constant at 280 bar.

The fresh cyclopentene feed is metered in at 205.4 g / h. This comes from the distillation of a Cs-section of a steam cracker and has the following composition (wt .-%): cyclopentene (about 94.7%), cyclopentane (about 4.5%), 2-methyl-2-butene ( about 1.0%), 2,2-dimethylbutane (about 0.14%).

Mixing this stream with a cyclopentene recycle stream produces a stream having the following composition: cyclopentene (about 92%), cyclopentane (about 6.9%), 2-methyl-2-butene (about 1.9%) , 2,2-dimethylbutane (about 0.32%), acetone (about 0.18%). This stream is then metered with a metering pump to the reactor (input N ₂ O, flow rate: 300 g / h). Liquid N ₂ O (content of N ₂ O> 99.5% by volume, from Linde) is added separately to the reactor at 129.2 g / h. The molar ratio of cyclopentene to N ₂ O in the reactor feed is about 0.72.

The cyclopentene conversion in the straight pass is 65% and the N ₂ O conversion is about 92%. The reactor discharge is relaxed after pressure maintenance in two steps with two at 11 bara and 1, 1 bara operated flash vessels to 1, 1 bara and cooled. The gaseous components are separated and in an aftercooler hydrocarbons contained therein are condensed out as completely as possible. The gas phase (about 88.8 g / h) has the following composition: N ₂ (89.4% by volume), N ₂ O (7.92% by vol.), Ethylene (790 vppm), cyclopentene (1 , 1 vol.%), Cyclopentane (0.21 vol.%), Further C ₅ components (803 vppm).

The liquid phase is separated in a distillation column (bubble-cap column with 5 column sections 106 cm × 50 mm, 10 plates each). The bottom product obtained is 229 g / h of a stream having the following composition (wt .-%): cyclopentanone (about 92.3%), cyclopentane (about 3.1%), 4-pentenal (about 1, 1% ), Isopropyl methyl ketone (about 0.34%), cyclopentene oxide (about 0.5%), cyclopentene dimers (about 0.25%), cyclopentene (about 0.19%).

From the overhead product containing 84.8% cyclopentene but no cyclopentanone, about 15.4 g / h are discharged to avoid accumulation of minor components, in particular acetone and 2-methyl-2-butene. The remainder (about 95 g / h) is returned to the reactor as a cyclopentene recycle stream.

After this procedure, the space-time yield is about 399 g cyclopentanone / liter reaction volume / hour. Thus, it takes 5.5x less reaction volume for the same amount of product. In addition, only 0.52 kg cyclopentane / cyclopentane mixture must be separated and partially recycled per kg of cyclopentanone produced instead of 8.2 kg according to Example 1. The energy required for this purpose is only 0.09 kWh / kg cyclopentanone instead of 0.73 kWh / kg according to Example 1.

Example 3: Reaction in the microreactor

Example 3 was carried out analogously to Example 2, but without the coils as a post-reactor. Coolant is pumped at approx. 16 l / min in the cooling circuit in order to dissipate the heat of reaction (Marlotherm SH from Sasol). The temperature of the incoming cooling medium is set to 280 ± 2 ⁰ C with an external thermostat.

The total available reaction volume (including connectors) is approx. 201 ml_. At the outlet of the last reactor is a pressure maintenance, which keeps the pressure in the reactor constant at 280 bar.

The fresh cyclopentene feed is metered in at 154 g / h. This originates from the distillation of a C _{5 cut of} a steam cracker and has the following composition (% by weight): cyclopentene (about 94.9%), cyclopentane (about 4.2%), 2-methyl-2 -butene (about 1.0%), 2,2-dimethylbutane (about 0.04%).

This stream is first mixed with a cyclopentene recycle stream to produce a stream having the following composition: cyclopentene (about 93.1%), cyclopentane (about 4.3%), 2-methyl-2-butene ( about 2.3%), 2,2-dimethylbutane (about 0.09%), acetone (about 0.41%).

This stream is then metered to the reactor with a metering pump (inlet N2, flow rate: 268 g / h).

Liquid N ₂ O (content of N ₂ O> 99.5% by volume, from Linde) is added separately to the reactor at 123 g / h (input N1). The molar ratio of cyclopentene to N ₂ O in the reactor feed is about 0.72 mol / mol.

The cyclopentene conversion in the straight pass is 54% and the N ₂ O conversion is about 76%. The reactor discharge is relaxed after pressure maintenance in two steps with two at 11 bara and 1, 1 bara operated flash vessels to 1, 1 bara and cooled. The gaseous components are separated and in an aftercooler hydrocarbons contained therein are condensed out as completely as possible. The gas phase (about 61.7 g / h) has the following composition: N ₂ (81.7 vol.%), N ₂ O (17.7 vol.%), Ethylene (674 vppm), cyclopentene (0 , 4% by volume), cyclopentane (402 ppm), further C ₅ components (346 vppm).

The liquid phase is separated in a distillation column (bubble-cap column with 5 column sections 106 cm × 50 mm, 10 plates each). The bottom product obtained is 165.4 g / h of a stream having the following composition (% by weight): cyclopentanone (about 93.8%), cyclopentane (about 3.0%), 4-pentenal (ca. 1.3%), cyclopentene oxide (about 0.5%), cyclopentene dimers (about 0.25%), cyclopentene (about 0.9%). From the top product, which contains 91.1% cyclopentene but no cyclopentanone, about 8.1 g / h are discharged in order to avoid accumulation of secondary components, in particular acetone and 2-methyl-2-butene. The remainder (about 14 g / h) is returned to the reactor as a cyclopentene recycle stream.

After this procedure, the space-time yield is about 823 g cyclopentanone / liter reaction volume / hour. Thus, for the same amount of product 11, it takes four times less reaction volume than in example 1. In addition, only 0.11 kg of cyclopentene / cyclopentane mixture per kg of cyclopentanone produced have to be separated off and partly recycled instead of 8.2 kg According to Example 1. The energy required for this purpose is only 0.09 kWh / kg of cyclopentanone instead of 0.73 kWh / kg according to Example 1.

Claims

claims

A process for the preparation of cyclopentanone comprising reacting a mixture (G1) containing at least cyclopentene with a mixture (G2) at least containing dinitrogen monoxide, the reaction in at least one reactor (R1) having channels with a diameter in the range of 0.1 mm up to 50 mm, the reactor having at least two zones (Z1) and (Z2) with channels of different diameters, and the diameter of the channels of the zone (Z1) being smaller than the diameter of the channels

Zone (Z2).

2. A process for the production of cyclopentanone according to claim 1, wherein the reactor (R1) has at least three zones (Z1), (Z2) and (Z3) with channels of different diameters, and the diameter of the channels of the zone (Z1) is smaller than the diameter of the channels of the zone (Z2) and the diameter of the channels of the zone (Z2) are smaller than the diameter of the channels of the zone (Z3).

The process for producing cyclopentanone according to claim 2, wherein the diameter of the channels in the zone (Z1) is in the range of 0.5 mm to 2.0 mm, the diameter of the channels in the zone (Z2) is in the range of 2 , 5 mm to 6.0 mm and the diameter of the channels in the zone (Z3) is in the range of 6.5 mm to 10.0 mm.

4. A process for the preparation of cyclopentanone according to any one of claims 1 to 3, wherein the reaction is carried out in two parallel reactors (R1) and (R2), each having channels with a diameter in the range of 0.1 mm to 50 mm, and in which the reactor (R1) and the reactor (R2) each have at least two zones (Z1) and (Z2) with channels of different diameters and the diameter of the channels of the zone (Z1) is in each case smaller than the diameter of the channels of the zone ( Z2).

5. A process for the preparation of cyclopentanone according to any one of claims 1 to 4, wherein the mixtures (G1) and (G2) are mixed in the reactor in the channels.

6. A process for the preparation of cyclopentanone according to any one of claims 1 to 5, wherein the reaction is carried out at a pressure of 200 to 500 bar and a temperature of 270 to 300 ⁰ C.

A process for producing cyclopentanone according to any one of claims 1 to 6, wherein the mixture (G1) contains at least 90% by weight of cyclopentene.

8. A process for the preparation of cyclopentanone according to any one of claims 1 to 7, wherein the mixture (G2) contains at least 70 vol .-% nitrous oxide.

A process for producing cyclopentanone according to any one of claims 1 to 8, wherein the mixture (G2) contains 75 to 99% by volume of dinitrogen monoxide.