EP1802596A1

EP1802596A1 - Method for producing olefin oxides and peroxides, reactor and the use thereof

Info

Publication number: EP1802596A1
Application number: EP05787485A
Authority: EP
Inventors: Steffen Schirrmeister; Bernd Langanke; Karsten BÜKER; Frank Becker; Johannes Albrecht; Georg Markowz; Rüdiger Schütte
Original assignee: Uhde GmbH
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 2004-10-15
Filing date: 2005-09-16
Publication date: 2007-07-04
Also published as: DE102004050506A1; NO20072459L; EG24502A; AU2005297530A1; MX2007004501A; EA013086B1; EA200700873A1; CN101044129A; ZA200702469B; CA2584049A1; NZ554394A; KR20070063004A; WO2006042598A1; BRPI0516517A; JP2008516900A; US20080306288A1; HRP20070150A2

Abstract

The invention relates to a method for reactions of peroxide compounds or reactions producing peroxide compounds in a wall reactor, the reaction chamber of the wall reactor being provided with a specific material coating. The inventive method is used to obtain both higher space-time yields and increased selectivities.

Description

description

Process for the preparation of olefin oxides and peroxides, reactor and its use

The present invention is directed to a process for the preparation of olefin oxides, in particular propene oxide, and peroxides by heterogeneously catalyzed gas phase oxidation in a wall reactor and to the use of particularly suitable reactors in the gas phase oxidation.

The epoxidation of olefins, such as propene, using oxygen in the liquid phase and in the gas phase is known.

DE 197 48 481 A1 describes a static micromixer and a microreactor with special microgeometry and their use for the preparation of oxiranes in the gas phase by catalytic oxidation of unsaturated compounds with air or with oxygen.

The epoxidation of olefins, such as propene, using hydrogen peroxide in the liquid phase and in the gas phase is a newer process variant.

Thus, US Pat. Nos. 5,874,596 and DE-A-197 31 627 describe the epoxidation of olefins in the liquid phase using a titanium silicalite catalyst. A disadvantage of this process is the rapid deactivation of the catalyst by high-boiling by-products.

The use of a wall reactor, more precisely a microreactor, in the oxidation of organic compounds in the liquid phase is known from EP-A-903,174. Here, a cooled microreactor is used, in which by the exothermic Oxidation reaction generated with peroxides heat can be dissipated accelerated. By carrying out the reaction at moderate temperatures, the decomposition of the liquid peroxide compound can be kept low.

From US-A ^, 374,260 the epoxidation of ethylene in the gas phase is known, wherein a silver-containing catalyst at 200 to 300 ⁰ C is used. The epoxidizing agent used is air or molecular oxygen.

Further epoxidation reactions of reactants in the gas phase are known from US-A-5,618,954, in the 3,4-epoxy-1-butenes over a silver-containing catalyst with oxygen-containing gases in the presence of water in a fixed bed reactor at temperatures of 100 to 400 ⁰ C to be implemented.

It has also been attempted to epoxidize lower olefins with hydrogen peroxide in the gas phase, whereby hydrogen peroxide is thermally or catalytically activated (see GM Mamedjarov and T M. Nagiev in Azerb. Khim. Zh. (1981), 57-60 and T M Nagiev et al in Neftekhimiya 31 (1991), 670-675). Disadvantages are the high reaction temperatures, which preclude an economic process.

Another method uses a Si-containing catalyst and Reaktions¬ temperatures 425-500 ⁰ C (comp. Gusenov HM et al. In Azerb. Khim. Zh. (1984), 47-51). In this case, a tubular reactor is used and the propene conversion is in the range of 15 to 65%.

Still another method uses an Fe-containing catalyst (see TM Nagiev et al., Neftekhimiya 31 (1991), 670-675). The reaction yields are about 30% and the catalyst has a very short life. Higher service lives and a further reduction in the reaction temperature can be achieved with an Fe '"-OH-protoporphyrin catalyst bound to aluminum oxide, which is heated at 16O ⁰ C and a temperature of about 16O ⁰ C

Use molar ratio of C3H6: H2O2: H2O = 1: 0.2: 0.8 obtained a propene oxide yield of about 50%. An improved process for the epoxidation of C ₂ -C ₆ -olefins in the gas phase is described in DE-A-100 02 514. The reaction takes place with gaseous hydrogen peroxide in the presence of selected catalysts. Suitable reactors are called fixed bed and fluidized bed reactors. According to this document, the reaction is carried out at temperatures below 250 ⁰ C, preferably in the range of 60 to 150 ⁰ C, and the olefin is used in equimolar amounts, preferably in excess.

Carrying out gas phase epoxidation of propene with H2O2 in one

Wall reactor, more precisely a microreactor, is known. Kruppa and Schüth, for example, have also investigated the epoxidation reaction in a microreactor (IMRET 7, 2003).

G. Markowz et al. in Chemie Ingenieur Technik 2004, 76 (5), 620-5 describe the gas-phase epoxidation of propene to propene oxide with vaporous hydrogen peroxide on titanium silicalite catalysts in a microreactor. Details of the reactor design and technical reaction conditions are not disclosed.

Based on this prior art, it is an object of the present invention to provide an improved process for the catalytic gas phase epoxidation of olefins with peroxide compounds in which with regard to a technical application, a high space-time yield with high selectivity of the thermally labile recyclable material Product is achieved. At the same time an improved process of peroxide production is the object of the invention.

It has surprisingly been found that when using wall reactors with catalyst contents in which at least one dimension of the reaction space is kept in the range of less than 1 cm and whose inner walls are coated with special materials, the product selectivity of the peroxidic oxidizing agent increases with increasing reaction temperature in contrast to classical fixed bed reactors increases and thus higher selectivities of the peroxidic used Are to determine oxidizing agent. Furthermore, it has been found that in the special reactors, surprisingly, peroxidic compounds also have increased stabilities, so that these reactors are also suitable for the synthesis of peroxidic compounds.

Another object of the present invention is to provide a reactor which is particularly suitable for the gas-phase reaction with and peroxidic compounds.

The present invention relates to a process for preparing an olefin oxide by heterogeneously catalyzed gas phase epoxidation of an olefin with a peroxidic compound in the presence of water and optionally an inert gas comprising the measures: i) carrying out the gas phase epoxidation at temperatures above 100 ⁰ C, ii) using a reactor of at least one reaction space, of which at least one dimension is smaller than 10 mm, iii) wherein the surface of the reaction space containing a layer

Alumina, zirconia, tantalum oxide, silica, tin oxide, glass and / or enamel, and iv) wherein the reaction space contains catalyst, preferably coated with catalyst or partially coated.

All known wall or microreactors can be used to carry out the process according to the invention. For the purposes of this description, wall reactors are to be understood as meaning those reactors in which at least one of the dimensions of the reaction space or the reaction spaces is less than 10 mm, preferably less than 1 mm, particularly preferably less than 0.5 mm.

The catalyst content of the reaction space / reaction spaces can also be extended to collection or distribution spaces, wherein a different catalyst content to the reaction space in these areas may be present. The reactor may have one or preferably a plurality of reaction spaces, preferably a plurality of reaction spaces running parallel to one another.

The dimensioning of the reaction spaces can be arbitrary, provided at least one dimension moves in the range of less than 10 mm.

The reaction spaces may have round, ellipsoidal, triangular or polygonal, in particular rectangular or square cross sections. Preferably, the or a dimension of the cross section is smaller than 10 mm, that is at least one side length or the or a diameter.

In a particularly preferred embodiment, the cross section is rectangular or round and only one dimension of the cross section, ie one side length or the diameter moves in the range of less than 10 mm.

The construction material of the reactor can be arbitrary provided that it is stable under the reaction conditions, allows sufficient heat dissipation and the surface of the reaction space with the above-mentioned special materials is completely or partially coated.

The reactor can thus consist of metallic materials, although its reaction space or reaction spaces with aluminum oxide, zirconium oxide, tantalum oxide, silicon dioxide, tin oxide, glass and / or enamel is coated.

Typical proportions of the sum of said oxides and / or glasses in the

Surface layer of the reaction space is in the range of 20 to 100 wt.%, Based on the material forming the surface layer of the reaction space.

In a particularly preferred embodiment, the reactor or at least the parts enclosing the reaction space are made of aluminum or one

Aluminum alloy. This material is known to oxidize in the presence of hydroperoxide compounds to alumina. A further feature of the reactor used according to the invention is that the reaction space contains all or part of the catalyst. Preferably, the surface of the reaction space is partially or completely coated with catalyst.

The catalyst can be applied to the special surface of the substrate or the reaction space is completely or partially filled with finely divided, optionally supported catalyst. The catalyst filled or coated volume is porous and permeable under the reaction conditions in the reactor to the reactants so that they can also contact the particular materials.

Surprisingly, it has been shown that with the specified special materials under the reaction conditions, the selectivity of the desired reaction with the temperature is increased and that the product yield of the peroxide used or produced is thereby increased.

The present invention thus also relates to a process for preparing a peroxidic compound by heterogeneously catalyzed gas phase reaction comprising the steps: v) carrying out the reaction by reacting a precursor for the peroxidic compound with oxygen and / or an oxygen-containing compound to the peroxidic compound at temperatures above 100 ⁰ C, vi) use of a reactor having at least one reaction space of which at least one dimension is smaller than 10 mm, vii) in which the surface of the reaction space contains a layer

Alumina, zirconia, tantalum oxide, silica, tin oxide, glass and / or enamel and viii) in which the reaction space optionally contains catalyst, preferably coated with catalyst or partially coated.

Precursor of peroxidic compounds is generally oxygen. Thus, the invention involves the production of hydrogen peroxide from hydrogen and oxygen in the special reactor. Also, organic molecules can be reacted with hydrogen peroxide to organoperoxidic compounds such as peracetic acid.

The invention also relates to a reactor for reaction with or to peroxidic compounds comprising: a) at least one reaction space of which at least one dimension is smaller than 10 mm, b) the surface of the reaction space has a layer containing alumina, zirconia, tantalum oxide, Silicon dioxide, tin oxide, glass and / or enamel, and c) the reaction space contains catalyst, preferably the surface of the reaction space is coated with catalyst or partially coated.

Another object of the invention is the use of specially coated reactors in the gas phase oxidation with peroxidic compounds or in the synthesis of peroxidic compounds, especially in heterogeneously catalyzed gas phase reactions.

In a particularly preferred embodiment of the method according to the invention, the gas phase epoxidation is carried out in a microreactor having a plurality of vertically or horizontally and parallelly arranged spaces, which have at least one supply line and one discharge, wherein the spaces are formed by stacked plates or layers, and a part of the spaces is reaction spaces, of which at least one dimension is in the range of less than 10 mm, and the other part of the rooms is heat transport spaces, the supply lines to the reaction spaces having at least two distribution units and the outlets from the reaction spaces to at least one Collection unit are connected, wherein the heat transfer between reaction and heat transport spaces is carried by at least one common room wall, which is formed by a common plate. A microreactor of this type which is particularly preferably used has spacer elements arranged in all chambers, contains at least partially catalyst material applied to the inner walls of the reaction chambers, has a hydraulic diameter which is defined as the quotient of four times the circumferential length of the free flow cross-section in the reaction chambers less than 4000 microns, preferably less than 1500 microns, and more preferably less than 500 microns, and a ratio between the perpendicular smallest distance between two adjacent spacer elements to the slot height of the reaction space after a coating with catalyst of less than 800 and greater than or equal to 10, preferably less than 450, and more preferably less than 100.

As olefins, it is possible to use all compounds which have one or more double bonds. Straight-chain or branched as well as cyclic olefins can be used. The olefins can also be used as mixtures.

The olefinic starting materials have at least two carbon atoms. Olefins of any number of carbon atoms can be used, provided that they are sufficiently thermally stable under the conditions of gas phase epoxidation.

Preference is given to using olefins having 2 to 6 C atoms. Examples thereof are ethene, propene, 1-butene, 2-butene, isobutene and also pentenes and hexenes, including cyclohexene and cyclopentene, or mixtures of two or more of these olefins, but also higher olefins. The process is particularly preferably suitable for the preparation of propene oxide from propene.

As peroxide compounds H ₂ O ₂ , hydro or organic peroxides can be used with any hydrocarbon radicals, provided that they are sufficiently thermally stable under the conditions of the gas phase reaction. As hydrogen peroxide can be used all evaporable compositions containing H ₂ O ₂ . Expediently, aqueous solutions of 30 to 90% by weight of hydrogen peroxide are used, which are evaporated and fed to the wall reactor. The gaseous hydrogen peroxide is recovered by evaporation in a suitable apparatus. To reduce subsequent reactions with the water resulting from the evaporation of aqueous hydrogen peroxide, highly concentrated H ₂ O ₂ solutions are preferably fed to the evaporator. As a result, the energy consumption is reduced.

As catalysts, any catalysts for the gas phase oxidation of olefins can be used with hydrogen peroxide.

One class of suitable and preferred catalysts are molecular sieves, especially synthetic zeolites. A particularly preferred catalyst from the series of molecular sieves is based on titanium-containing molecular sieves of the general formula (SiO ₂ ) i _-x (TiO ₂ ) _x , such as titanium silicalite-1 (TS1) with MFI crystal structure, titanium silicalite-2 (TS-2) MEL crystal structure, titanium beta zeolite with BEA crystal structure and titanium silicalite-48 having the crystal structure of zeolite ZSM 48. The TiO ₂ content in TS-1 is preferably in the range of 2 to 4%. Titanium silicalites are commercially available. Instead of pure titanium silicalites and combination products, which except

Titansilikalit also amorphous or crystalline oxides such as SiO ₂ , TiO ₂ , Al ₂ O ₃ and / or ZrO ₂ included.

In this case, crystallites of titanium silicalite may be homogeneously distributed with the crystallites of the other oxides and form granules or be located as an outer shell on a core of other oxides.

Another class is organometallic catalysts, for example organo-iron (protoporphyrin) or organo-titanium compounds on a suitable support. Another class of preferred catalysts used are preferably inorganic, in particular oxidic compounds which contain as catalyst-active element one or more elements of the 4th to 6th subgroup of the Periodic Table and / or an arsenic and / or selenium compound.

Particularly preferred are compounds of titanium, vanadium, chromium, molybdenum and tungsten.

The catalytic effect of these compounds is, without excluding other mechanisms, seen in the fact that the peroxidic starting material is activated by the porous structure of the catalyst and / or by the ability of the catalyst for the reversible formation of peroxo compounds.

Examples of particularly suitable catalysts are vanadium oxides, vanadates and their h ^ Cb adducts.

Another particularly suitable class of epoxidation catalysts contain molybdenum or tungsten. Examples are MoO ₃ and WO ₃ , molybdenum and tungstic acids, alkali metal and alkaline earth metal alkoxide and tungstates, unless their basicity leads to hydrolysis of the epoxide, homo- and heteropolymolybdates and tungstates

(= Homo- and heteropolyacids) and H2Ü2 adducts of the mentioned classes of substances, such as peroxomolybdic acid, peroxotungstic acid, Peroxomolybdate and Peroxowolframate, which can also be formed in situ during the epoxidation of other Mo and W compounds.

Catalysts for the production of hydrogen peroxide are e.g. Gold, palladium or other precious metals on suitable supports, e.g. on carbons or on SiO 2. For the preparation of organoperoxidischer compounds no catalyst is generally needed.

For the preparation of a particularly suitable coating, the catalyst was combined with a binder which was inert to the epoxidation reaction Part or applied to all walls of the reaction space. A particular challenge lies in the properties of the binder that are as inert as possible to the gaseous peroxidic compound.

There are numerous examples of inactive binders for liquid applications. However, most substances show marked differences in their catalytic decomposition properties compared with gaseous peroxidic compounds. The use of a coating containing aluminum, silica or silicate has proven to be particularly preferred. These preferred catalytic coatings can be formed by mixing the inactive binder with the active component, preferably with the powdered active component, by shaping and annealing.

In another embodiment, catalysts are used whose effective component is applied to a porous support. As a result, a particularly large internal volume can be generated, which leads to particularly high reaction yields

The starting materials for the processes according to the invention are fed to the wall reactor. The feeds may contain other components, for example water vapor and / or other inert gases.

The processes are typically carried out continuously.

It is essential that during the reaction in the wall reactor, ie

Catalyst, no liquid phase is formed. As a result, the catalyst life is increased and reduces the cost of regeneration.

In addition, other gases, such as low-boiling organic solvents, ammonia or molecular oxygen may be added to the educt gas mixture. The olefin to be epoxidized can in principle be used in any ratio to the peroxidic component, preferably to the hydrogen peroxide.

In general, increasing yields of epoxide are achieved with increasing molar ratio of olefin to the peroxidic component, preferably to H2O2. Preference is given to using molar ratios of olefin to the peroxidic component in which the olefin is present in excess, preferably in the range from 1.1: 1 to 30: 1.

The gas phase reactions are carried out at a temperature above 100 ⁰ C, preferably at a temperature above 140 ⁰ C. Preferred reaction temperatures are in the range 140-700 ⁰ C, in particular in the range of 140 to 250 ° C.

Conveniently, the gas phase reactions take place in a pressure range from 0.05 to 4 MPa, preferably 0.1 to 0.6 MPa.

The work-up of the reaction mixture can be carried out in the manner known to those skilled in the art.

The inventive method is characterized by the simple reaction, high space-time yields at the same time high selectivity of the valuable oxidizing agent.

Special provisions for explosion protection can be omitted in the particularly preferred microreactor.

The following examples illustrate the invention without limiting it.

All experiments were carried out in an apparatus consisting of an evaporator and a micro-reactor in which the hydraulically effective diameter was less than 1 mm and made of aluminum. There were commercial stabilized 50 Wt.% Hydrogen peroxide solutions and different catalysts used. The measurement and metering of the gas streams (propene, nitrogen) and the hydrogen peroxide solution was carried out with mass flow sensors from Bronkhorst.

In the evaporator made of glass (100 ⁰ C) were a 50 wt. % hydrogen peroxide solution and a preheated to the evaporator temperature gas mixture of propene and nitrogen metered. The gaseous mixture leaving the evaporator and consisting of 18 ml / min of H ₂ O ₂ , 53 ml / min of propene, 247 ml / min of N ₂ and the water fractions was reacted at different temperatures of 100 to 180 ^° C. in the microreactor. The reactor was coated therewith with 0.3 g of titanium silicalite-1 catalyst.

Contrary to expectations, an enlarged enlarged propylene oxide selectivity of the valuable oxidizing agent was measured in the micro-reactor. The results are shown in the table below. With an increase in the reaction temperature from 100 to 140 ° C, the selectivity increased by 100%.

Kruppa, Amal and Schüth have investigated the temperature influence of the heterogeneous titanium silicalite-1 catalyzed gas-phase epoxidation of propene with H ₂ O ₂ in a glass fixed bed reactor (Europacat IV, 2003). The results are shown in the table below. As expected, the PO selectivity of the reacted H ₂ O ₂ steadily decreased with increased reaction temperature. Increasing the reaction temperature from 100 ⁰ C to 14O ⁰ C, the selectivity decreased by 15%.

In an epoxidation in the micro-reactor, therefore, both increased propylene oxide selectivities of the oxidizing agent and increased space-time yields are possible in comparison to the known state of the art with increased temperature. The effect can not be achieved in a conventional fixed bed reactor with hydraulic effective diameters of 1 cm. Thus, the effective hydraulic diameter for the effect will be below 1 cm.

Claims

Claims 204ku04.wo

1. A process for preparing an olefin oxide by heterogeneously catalyzed gas phase epoxidation of an olefin with a peroxidic compound comprising the measures: i) carrying out the gas phase epoxidation at temperatures above 100 ⁰ C, ii) using a reactor having at least one reaction space, of the at least one dimension is smaller than 10 mm, iii) wherein the surface of the reaction space is a layer containing alumina, zirconia, tantalum oxide, silica, tin oxide, glass and / or

Having enamel, and iv) wherein the reaction space contains catalyst.

2. The method according to claim 1, characterized in that a reactor is used, wherein the reaction space is coated with catalyst or partially coated.

3. The method according to claim 1, characterized in that the olefin is an olefin having 2 to 6 carbon atoms, preferably propene, is used and that is used as ~ peroxide compound H2O ₂ .

4. The method according to claim 1, characterized in that the reactor has a plurality of mutually parallel reaction spaces, of which in each case at least one dimension, preferably only one dimension in each case, less than 1 mm, in particular less than 0.5 mm.

5. The method according to claim 4, characterized in that the gas phase epoxidation is carried out in a microreactor having a plurality of vertically or horizontally and parallelly arranged spaces, which have at least one supply line and one discharge, wherein the spaces through stacked plates or layers are formed, and represents a part of the rooms Reak¬ tion spaces and the other part of the rooms heat transfer rooms, the supply lines to the reaction chambers with at least two Distributor units and the derivatives of the reaction chambers are connected to at least one collecting unit, wherein the heat transfer between the reaction and heat transport spaces through at least one common room wall, which is formed by a common plate.

6. The method according to claim 5, characterized in that the microreactor has arranged in all rooms spacer elements, that on the inner walls of the reaction chambers at least partially catalyst material is applied, wherein the hydraulic diameter, which is defined as the quotient of the quadruple surface to the circumferential length of free flow cross section, in the

Reaction spaces is less than 4000 microns, and that a ratio between the perpendicular smallest distance between two adjacent spacer elements to the slot height of the reaction space after a coating with catalyst of less than 800 and greater than or equal to 10.

7. The method according to claim 1, characterized in that a compound of an element of the 4th to 6th subgroup of the Periodic Table and / or of arsenic or selenium and / or a molecular sieve is used as the catalyst.

8. The method according to claim 7, characterized in that a titanium-containing zeolite, in particular titanium silicalite-1 (TS-1) having a TiO 2 content in the range of 2 to 4% is used as the catalyst.

9. The method according to claim 1, characterized in that the catalyst is an organometallic compound, in particular an iron or organo-organic

Connection is used.

10. The method according to claim 7, characterized in that the catalyst is an oxidic compound of vanadium or a molybdenum or tungsten compound from the series of oxides, acids, Molybdate, tungstates, molybdenum or tungsten-containing homo- or heteropolyacids and H ₂ θ ₂ adducts of these classes are used.

11. The method according to claim 1, characterized in that catalysts are used, the effective component is applied to a porous support.

12. The method according to claim 1, characterized in that the catalyst is present together with a relative to the epoxidation reaction binder applied to the surface of the reaction space.

13. The method according to claim 12, characterized in that the inert binder consists essentially of alumina, silica or silicates.

14. The method according to claim 1, characterized in that the implementation of the gas phase epoxidation takes place at temperatures of 140 to 700 ⁰ C, preferably 140 to 250 ⁰ C.

15. The method according to claim 1, characterized in that the gas mixture containing olefin and peroxidic compound is contacted at a pressure in the range of 0.05 to 4 MPa.

16. The method according to claim 1, characterized in that the gas mixture containing olefin and peroxidic compound in a molar ratio of greater than 1: 1, preferably in the range of 1, 1: 1 to 30: 1 is used.

17. A process for the preparation of a peroxidic compound by heterogeneously catalyzed reaction in the gas phase comprising the measures: v) carrying out the reaction by reacting a precursor for the peroxidic compound with oxygen and / or an oxygen-containing compound to the peroxidic compound at temperatures above 100 ⁰ C, vi) use of a reactor having at least one reaction space of which at least one dimension is smaller than 10 mm, vii) wherein the surface of the reaction space comprises a layer containing alumina, zirconia, tantalum oxide, silica, tin oxide, glass and / or enamel and viii) in which the reaction space optionally contains catalyst.

18. reactor for the reaction with or to peroxidic compounds comprising: a) at least one reaction space, of which at least one dimension is smaller than 10 mm, b) the surface of the reaction space has partially or completely a layer containing alumina, zirconia, tantalum oxide, silicon dioxide .

Tin oxide, glass and / or enamel, and c) the reaction space contains catalyst.

19. A reactor according to claim 18, characterized in that the surface of the reaction space is coated with catalyst or partially coated.

20. Reactor according to claim 18, characterized in that at least one dimension of the reaction space is less than 1 mm, more preferably less than 0.5 mm.

21. Use of the reactor according to any one of claims 18 to 20 for the gas phase oxidation with peroxide compounds.

22. Use of the reactor according to any one of claims 18 to 20 for the synthesis of peroxidic compounds.