KR20030022131A - Device and method for carrying out heterogeneously catalysed gas phase reactions with heat tonality - Google Patents

Abstract

The present invention relates to an apparatus for carrying out a hybrid catalyzed reaction in a hot gas phase in a substantially isothermal manner. The designed device includes at least one reaction chamber 101 having an inlet 131, 141 and an outlet 143. The reaction chamber is formed of a heat diffusion wall placed at a substantially constant distance of 30 mm or less along the flow main axis of the reaction gas. The reaction chamber is equipped with catalyst coated strips 120, 132. The strip is permeable to the reaction gas, is flexible in all directions of the reaction chamber, has good thermal conductivity and an area / volume ratio of 50 to 5000 m 2 / m 3. The reaction gas in the reaction chamber flows at a rate of 200 m 3 or more per area of m 2 per hour, and the heat exchange medium flows on the side of the reaction wall opposite the reaction chamber.

Description

DEVICE AND METHOD FOR CARRYING OUT HETEROGENEOUSLY CATALYSED GAS PHASE REACTIONS WITH HEAT TONALITY}

DE-A 42 43 500 discloses the use of a catalyst coated knitted wire insert for exhaust gas cleaning. The layers of knitted or woven wire are thermally and / or mechanically fixed in a wound state. The problem is the complex structure of the catalyst insert and the poor heat transport inside this complex structure.

DE-A 41 09 227 includes i) a feed conduit and ii) said feed conduit is led to a filter or catalyst body comprising a metal material structure, wherein the metal material structure of the filter or catalyst body is full of voids and exhaust gas. For use in any braided, knitted or woven fabric or in the form of powder, particulates or chips, compression molded wires or fibers, iii) for exhaust gases purified by a filter or catalyst body An exhaust gas filter and / or catalyst having an exhaust conduit is disclosed.

The filter or catalyst body may have heat exchanger pipes or conduits passing transversely or oppositely in the direction of exhaust gas flow through the filter or catalyst body.

EP-B 201 614 describes a heterogeneous catalytic chemistry reaction reaction apparatus comprising an at least partially corrugated tape-like catalyst body, wherein the corrugations are inclined to the main flow axis and guided to adjacent plates, the corrugations of the catalyst body. The pitch of is smaller than the pitch of the adjacent corrugated plate, and the surface of the catalytic region is larger than the surface area of the adjacent corrugated plate. The catalyst may be a body which is coated with a catalytically active material and which may consist of braided or knitted wire. The complex corrugation of the plate is suitable for bypass formation and prevents vortices, weakening mass transfer. Furthermore, the compact packing elements provided do not allow for effective removal of the reaction heat.

EP-B 0 305 203 describes the action of heterogeneous catalysis under non-insulating conditions. To this end, a cyclic reactor chamber with heat transfer walls is provided with a monolithic catalyst in the form of a catalyst sheet. The monolithic catalyst has a channel that is inclined to the entire flow direction so that the reaction fluid is sent at an acute angle from one reactor wall to the other. The shear stresses applied to the reaction fluid are extremely large (large pressure drop) near the reactor wall, otherwise somewhat small (weak mass transfer). The reactor is complex to fabricate because the pressure drop is absolutely dependent on the geometry between the reactor wall and the monolithic catalyst.

EP-B 0 149 456 comprises a channel 1-10 mm in diameter which is approximately the same diameter as the reactor tube and is guided from the inlet to the outlet of the reactor tube and between 60% and 90% of the volume is defined by the hollow space. A method for preparing glyoxyl esters by oxy dehydrogenation of the corresponding glycolic esters in the gas phase using a tubular reaction device comprising a catalyst support made of at least one cylindrical monolith formed. The channel may form an angle of 20 ° to 70 ° with respect to the reactor axis. This measure leads the reaction fluid to the reactor wall to improve the removal of reaction heat. This method has the same disadvantages as the method known from EP-B 0 305 203.

DE-E 197 25 378 describes a compact fixed bed reaction apparatus for catalytic reaction in gas and / or liquid phases traversed by two mass streams of cocurrent or countercurrent. The flow channels for the two mass flows are formed by the flexible partition wall. The folds of this dividing wall were formed undulating in such a way that a continuous flow channel was created for the fluid flow. The wavy structure is used as a spacer and catalyst support between opposing folds of the dividing wall and ensures improved heat transfer to and from the dividing wall. The wavy structure is a rigid structure having dimensions that limit the minimum separation between the folds of the dividing wall and also the amount of catalyst that can be applied to this wavy structure. The ratio of the surface area of the wavy structure (ie catalyst) to the heat exchanger volume is no greater than 800 m 2 / m 3 based on a maximum industrially feasible folding width of 5 mm and a folding angle of 90 °.

The present invention relates to a method and apparatus for near isothermal operation of gas phase reactions, in particular oxidative dehydrogenation reactions, including significant heat release via a solid catalyst.

The invention will now be described in more detail with reference to FIGS.

1 schematically shows a diagram of a flat plate heat exchanger reactor according to the present invention.

2 is a side view of the interior of the helical heat exchanger reactor.

3 is a further side view of the helical heat exchanger reactor.

It is an object of the present invention to provide a reactor for operating a heterogeneous gas phase reaction comprising significant exotherm combining good heat removal and feed at the site of heterocatalytic reaction having a good surface to volume ratio for the catalyst.

It can be seen that this object is achieved by an apparatus for virtually isothermal operation of heterocatalytic gas phase reactions involving significant exotherm, comprising at least one reactor space having an inlet and an outlet.

The reactor space is bounded by substantially uniformly spaced heat removal walls at a distance of 30 mm or less along the main flow axis of the reaction gas,

The reactor space is equipped with a catalyst coated tape,

The tape is flexible, penetrates the reaction gas in all spatial directions, has a surface for a volume ratio of 50 to 5000 m 2 / m 3, and also has good thermal conductivity,

The reaction gas flows through the reactor space at a rate of at least 200 m 3 per square meter of the frontal area per hour,

The heat exchange medium flows on the side of the reactor wall remote from the reactor space.

The main apparatus is actually useful for operating not only exothermic but also virtually endothermic reactions, because they provide for rapid heat removal and heat exchange respectively. In fact, one example of an endothermic reaction includes an oxidative dehydrogenation reaction such as 3-methyl-3-buten-1-ol, while one example of an exothermic reaction in fact comprises a hydrogenation of double or triple bonds and also benzene to cyclohexane It is aromatic like hydrogenation reaction. The enthalpy of the reaction is for example in the range of 30 to 75 kal / mol.

It is also possible for the main apparatus to operate under atmospheric pressure, as well as under reduced or elevated pressure, ie at a pressure of 1 · 10 ⁻³ to 100 bar, in particular 0.5 to 40 bar. Thus, the main device can be used over a wide pressure range.

Reactant gases for the purposes of the present invention represent a mixture of gaseous reactants and optionally add other gaseous substances that do not react with the reactants under the reaction conditions. The heat exchange medium may be a liquid, gas or molten salt bath, depending on the desired temperature. When a heat exchange medium is used to absorb and remove heat, it is also known as a cooling fluid. Temperatures of -20 ° C to 400 ° C can be achieved efficiently. Rapid heat removal or heat supply makes it possible for the main unit to provide very accurate heat control. For example, it is possible to set a temperature of 370 ° C ± 10 ° C, in particular ± 5 ° C. Compared to the old fixed bed reactor, there is no temperature spike due to the use of the main apparatus.

The reactor space can be annular, cylindrical, rectangular, square.

The main apparatus can be easily realized by installing a catalyst coated tape (catalyst tape) into the gap of a commercially available heat exchanger. Thus, the reactor tube is not compliant with the catalyst while the catalyst tape is compliant with the reaction space. Any desired heat exchanger can be used. Spiral heat exchangers as well as annular gap heat exchangers are useful. Examples of heat exchangers are in ISO 15547, or Ver. Er. Ah. Bauk, ha. Ah. Müller's Dresden Theodor Steinkov Press, 1974, "Unit-Operated Chemical Process Technology," fourth edition pages 438 to 440, or the German Institute of Engineers Publications, Third Edition 1977, in the MB1 section of the VDI Scheme (CB3). To achieve the heat transfer described in the section).

The gap width or gap diameter of the wall gap and the heat exchanger used is preferably in the range from 0.5 to 30 mm, in particular in the range from 1 to 20 mm, in particular from 1.5 to 10 mm or from 1.8 to 5 mm.

When an annular gap heat exchanger is used, the catalyst tape is installed in the reactor space formed by two coaxial tubes and is cooled (or heated respectively) through the walls of the inner tube and / or the outer tube. This device according to the invention is also known as an annular gap heat exchanger reactor.

The plate heat exchanger has a square or rectangular reactor space that is selectively separated by additional heat conducting walls that pressurize the reaction gas to take a zigzag course through the reactor space. The plate heat exchanger reactor according to the present invention is completed by installing a catalyst tape in the reactor space and, if necessary, is completed without the catalyst tape where the change of direction is used where it is greatest to avoid excessively large pressure drops.

The apparatus using a helical heat exchanger ("spiral heat exchanger reactor") has a cylindrical reactor space which is particularly uniformly packed with catalyst tape.

The catalyst tape is a sheet-like smooth structure that can be formed into a perforated plate or rib mesh when the woven material, loop-drawn knit, loop forming knit, or the constituent material is a metal. It is also possible to use felts, films or foils, but they may be fabrics such as loop pull knits, loop forming knits, perforated plates or ribbed meshes and felt, film or foils oriented parallel to the mainstream direction and loop pull knits, loop forming knits The perforated plates or rib meshes must be combined in such a way that they serve as spacers for felt, film or foil. Also, when installed in the reactor space, felt, film or foil may be oriented alternately with the mainstream direction alternately with fabric, loop pull knit, loop forming knit, perforated plate or rib mesh. Preferred examples of using woven, loop pull knits or loop forming knits are disclosed.

The catalyst tape is flexible, ie bendable and stretchable in all directions of space. Thus, they are catalyst tapes with no uniform structure that readily correspond to the dimensions of the reactor space, in particular the gaps of commercial heat exchangers. Using them does not require any fixation or direction to the flow spindle. Since the catalyst tape is flexible in all directions of the space, it is fixed automatically. In general, the catalyst tapes are each bent or layered into the reactor space without pre-deformation (such as embossing of surface structures such as pleats by means of toothed wheel rolls). This allows for a higher packing density for the combined catalyst tape with uniform filling of the reactor space with maximum inhibition of undesirable bypass formation to achieve increased mass transfer. The catalyst tapes are installed by manually stacking, standing up or pressing them into the gap of the heat exchanger. The limiting factors are the dimensions of the reactor space and the thickness of the catalyst tape. Not only one catalyst tape but also a plurality of catalyst tapes may be installed. The catalyst tape can be placed over the entire reactor space of the heat exchanger as well as in sections selected by the skilled person. Because the catalyst tape is flexible in all directions of space, it can be extended as well as laminated, folded or curved. Extension means the lengthwise or widthwise direction of the catalyst tape. For example, if the perforated sheet cannot be extended, the catalyst tape can be extended by 60% depending on the structural material. Lamination means the overlap of at least two catalyst tapes, and folding means overlapping the same catalyst tape in the direction of the tape varying 180 ° within a particular or optionally selected section. The layered catalyst tape may optionally be folded or curved.

The surface area of the catalyst tape can be increased by expressing the fold or curvature of the catalyst tape, generally without a substantial increase in the volume of this fold or curved catalyst tape. The catalyst tape has a high surface to volume ratio in the range of 50 to 500 m 2 / m 3. Such high surface-to-volume ratios are not achieved with catalyst monoliths or dumpable catalyst materials and do not achieve such high ranges of variation in control of such surface-to-volume ratios. For example, such high modification ranges are not achieved in the structural space disclosed in DE-A 197 25 378. In addition, the catalyst tape permeates the reactant gases in comparison to the constituent catalyst materials, such as monolithic or dumpable materials, and has good heat transfer coefficients (see the VDI Heat Schematic 3rd Edition CB3 section published by VDI Publishing in 1997). With good thermal conductivity, heat in the reactor is quickly transferred over the catalyst tape to the reactor wall and vice versa. Another factor that promotes rapid heat transfer is the small wall space in the reactor space, which is generally ≦ 30 mm, preferably ≦ 20 mm, particularly preferably ≦ 10 mm. The volume of the reactor space is predetermined by the volume of the gap of the commercial heat exchanger.

In addition, the catalyst tape is mechanically very stable such that the hybrid catalyzed gas phase can be operated without a reduction in catalyst even at high flow rates for the reaction gas. The device can be operated even at low flow rates, but especially when the flow rate is above 200 (m 3 / front area (M²) · ｈ) but the flow rate is above 300 (m 3 / front area (M²) · ｈ). Preferably, when the flow rate is 1000 (m 3 / front area (M 2) · ｈ), it is superior to conventional reactors with catalyst monoliths or disposable catalyst materials.

The flow rate is selected as a function of the process (action at reduced pressure, atmospheric pressure or elevated pressure) and the ratio of catalyst tape volume to reactor space volume. Gas flow rates of up to 70 m / s can be realized in the apparatus of the present invention before the catalyst tape is installed. Typical values of gas flow rates in the heat exchanger are 40 m / s. When the device according to the invention is packed with a catalyst tape, the device can be operated at a flow rate of 200 to 15000 (m 3 / front area (M²) · ｈ), in particular 300 to 15000 (m 3 / front area (M²). At a flow rate of ()), more particularly at a flow rate of 1000 to 15000 (m 3 / front area (M²) · ｈ). The speeds mentioned are area speeds determined using a gas meter.

These high flow rates are not feasible with disposable catalyst materials and due to high pressure drops associated with consumption. Since in the device according to the invention a considerable pressure drop can be avoided by selecting an appropriate flow rate, in this case a compressor is not required to compensate for the pressure drop, so the use of this device provides additional cost savings over the use of conventional reactors. to provide.

Due to the mechanical stability, the catalyst tape is simply removable from the reactor spaces and is simply interchangeable without the problem of removing fine catalyst attrition associated with the discardable catalyst material. When such an unstructured crystalline tape is used, it is surprising that the choice of hybrid catalyzed reaction in the gas phase can be maintained or improved by rapid heat transfer.

The device is also designed to maintain a high but uniform shear stress on the reaction gas. First, the apparatus can withstand high cross-sectional flow rates without reducing the catalyst as described above. Second, the reaction gas is exposed to a uniform high shear stress in the reactor space filled with the catalyst tape. This provides uniform mixing of the reaction gases to provide a constant degree of dispersion of the reaction gases as they pass through the reactor space. Efficient mixing of the reactant gases and high flow rates are in accordance with the invention, although the operation of the reactions in the apparatuses according to the invention has a lower catalyst demand compared to the operation of the reactions of conventional reactors. Means that they provide a conversion similar to conventional reactors. Another advantage of the device is that cost savings are possible because the catalyst or catalyst support need not be expensive.

In general, the catalyst tape has a fine configuration. In the case of woven and loopdrawn knits, the fine structure is present in a rectangle formed by wires or yarns that share sides to each other. In fact, it is preferable that the pitch angle formed on one of the two sides of the rectangle having the main flow axis of the reactant gas be arbitrarily distributed. 'A randomly distributed pitch angle' means that the catalyst tapes are injected into the reactor space in such a way that ideally all possible pitch angles are implemented and ideally a chaotic net is formed as a result. In this chaotic net, the continuation of the voids, wires and yarns in the reactor space is disordered as a result of any orientation of the catalyst tape. This minimizes the bypass formation of the reactor and maximizes heat and mass transfer as a result of turbulent conditions.

The materials of the structure used for the support are selected from the group comprising metal, ceramic and plastic materials of the structure that match the deformations occurring during production, reshaping and use. Useful metal, ceramic and plastic materials of construction generally form fibrous tissue. Examples of such metal materials of construction are pure metals or steels such as iron, copper, nickel, silver, aluminum and titanium, for example nickel, chromium and / or molybdenum steels, brass, phosphor bronze, Monel and / or nickel It is an alloy like silver. Examples of the ceramic material of the structure are aluminum, silica (glass fiber) zirconia and / or carbon. Examples of plastics are polyamides, polyethers, polyvinyl, polyethylene, polypropylene, polytetrafluorodecylene, polyketones, polyether sulfones, epoxy resins, alkyd resins, urea and / or melamine resins. Due to the very good heat transfer rates, metals, asbestos substitutes, glass fibers, carbon fibers and / or plastics are preferred, in particular metals, ie pure metals or alloys. Inexpensive stainless steels with appropriate catalyst coatings are particularly preferred.

The tape coated with the catalyst according to the invention is in particular a metal fabric drawn into a metal fabric or loop. For the purposes of the present invention, the looped metal knit is a metal fabric formed from one continuous metal yarn. In contrast, a metal fabric is a fabric formed of at least two metal yarns. The wire diameter is in the range of 0.01 to 5.0 mm, preferably 0.04 to 1.0 mm in the case of metal fabrics or metal knits drawn in loops. Mesh size can vary within limits of width.

Catalyst tapes can be prepared by the processes described in US Pat. No. 4,686,202 and EP-B 0 965 384.

The catalyst tape embodied as a metal fabric may be further coated by the process described in EP-B 0 564 830. EP-B 0 564 830 does not explicitly describe coating metal knits drawn in loops with a catalyst, but they will be treated in the same way as metal fabrics. The coating of the metal fabrics or metal knits drawn in a loop with a catalyst may also be accomplished by conventional dip processes according to the process described for example in EP-A 0 056 435.

The contents of US Pat. No. 4,686,202, EP-B 0 965 384, EP-B 0 564 830 and EP-A 0 056 435 are hereby incorporated by reference in their entirety.

When the metal forming the metal fabric or metal knit pulled into the loop is itself catalytically reactive (perhaps after treatment), the coating will be distributed throughout.

1 shows a plate heat exchanger reactor 101 of the present invention. The catalyst coated tape is indicated at 120. 131 represents the supply of the reaction gas to the reaction space, and 143 represents its outlet line. Supply and outlet lines for the cooling fluid are indicated at 144 and 142, respectively.

2 is a side view of a helical heat exchanger reactor according to the present invention. 131 represents the supply of the reaction gas to the reaction space (reactor inlet). 132 represents the reaction passageway to receive the catalyst coated tape, which will take up the entire space in a rather dense packing. 133 represents a cooling passage to receive the cooling fluid.

Figure 3 is a side view of the spiral heat exchanger reactor and shows the arrangement of the feed and discharge stubs. 141: supply of reaction gas (reactor inlet), 142: discharge of cooling fluid, 143: discharge of reaction gas (reactor outlet), 144: supply of cooling fluid. The reactant gas and cooling fluid are here arranged in countercurrent so that heat transfer can be maximized. In particular, if the amount of heat released at the reactor inlet is important, for example, for selectivity and catalyst stability, a cocurrent arrangement is justified.

The present invention will be explained by the following examples.

The oxidation of 3-methyl-3-buten-1-ol to 3-methyl-2-butenal in gas is given by Equation I.

(I)

The reaction is carried out via silver catalyst. The catalyst according to the invention is prepared by coating a woven tape of material No. 1.4764, heat-resistant stainless steel (according to Stahl-Eisnistor 8 edition published by Verein Deutscher Eisenfittenrete) with silver in an electron beam deposition unit. do. This coating technique is used to coat on both sides of woven metal tape with Ag at 300 nm. 50 cm 2 of this woven catalyst tape is introduced into the 2 mm wide annular gap heat exchanger reactor without deformation into a double layer. The amount of active ingredient is 34 mg. To oxidatively dehydrogenate 3-methyl-3-buten-1-ol (MBE), a mixture of 85 wt% MBE and 15 wt% H 2 O is evaporated at 150 ° C., mixed with preheated air, and preheater It overheats by the inlet temperature of 370 degreeC by it.

After leaving the annular gap, the gaseous reaction product is cooled to 0 ° C. by cooling water and the condensate is collected in the cooled separator. The gaseous portion of the reaction product passes through dry ice and passes through a gas chromatography analyzer and a gas flow meter to waste. The combined amount of condensate is separated in an organic and aqueous state. All states are analyzed. From a conversion rate of 54%, a result of a selectivity of 83% is obtained.

Comparative example

Instead of an example annular gap heat exchanger reactor of the present invention, a non-volatile bed reactor having a layer of 30 mm depth of silver particulates according to Germany-A 27 15 209 is installed in the same plant and the conversion of MBE is similar to the example of the present invention. Similarly executed. The results are summarized in the table below.

catalyst Reactor Apparent velocity of MBE [g / cm ² h] Apparent velocity of air [l / cm ² h] % Conversion Selectivity [%] Woven tape coated with a 300 nm layer of Ag (total 30 mg Ag) Annular clearance heat exchanger reactor, passage width 2mm 279 94 54 83 Ag fine particles, 17 g of Ag, about 4.5 cm ³ Inert bed reactor, bed height 30 mm 69 27 54 73

It can be seen that the selectivity of the comparative example is 10% worse than the example of the present invention for the same conversion rate.

Also, the example of the present invention is more economical since 0.034 g is used instead of 17 g of silver. Another economic benefit is that higher flow rates can be adopted to enable higher hourly conversion rates.

Claims (9)

A device for virtually isothermal operation of a hybrid catalyzed gas phase reaction comprising at least one reaction space 101 having an inlet 131, 141 and an outlet 143 and comprising a constant heat release point, The reaction space is bounded by thermally moving walls that are arranged substantially uniformly spaced at a distance of 30 mm or less along the flow principal axis of the reaction gas, The reaction space is installed with catalyst coated tapes 120, 132, The tapes are flexible and pass through the reaction gas in all spatial directions and have an area to volume ratio of 50 to 5000 m 2 / m 3, and also have good thermal conductivity, The reaction gas flows through the reaction space at a rate of at least 200 m 3 per m 2 of the front area, The heat exchange medium flows on the side of the reaction wall away from the reaction space. The apparatus of claim 1 wherein the reaction space is defined by a gap in the heat exchanger. The device according to claim 1 or 2, wherein the reaction space is formed by the gap of the helical, plate or annular gap heat exchanger. The device according to claim 1, wherein the tapes are formed of metal, asbestos, glass fiber, carbon fiber and / or plastic. 5. Device according to claim 4, characterized in that the tapes (120, 132) are formed of a metal fabric drawn out of a metal fabric or loop. 6. The method according to any one of claims 1 to 5, wherein the order of gaps, wires or screws in the reaction space is free from rules established as a result of any arrangement of tapes 120, 132 with respect to the flow main axis of the reaction gas. Device characterized in that. The device according to claim 1, wherein the walls of the reaction space are spaced apart by 0.5 to 30 mm, preferably 1 to 20 mm, more preferably 1.5 to 10 mm. Use of the device of claim 1 in a process for oxidizing an alcohol in the gas phase. Use of the device of claim 1 in a process for oxidizing 3-methyl-3-buten-1-ol to 3-methyl-2-butenal in the gas phase per formula I. (I)