TWI324994B - Heterogeneously catalyzed partial gas phase oxidation of acrolein to acrylic acid - Google Patents

Description

1324994 发明, invention description: [Technical field of the invention] The present invention relates to a method for partially oxidizing acrolein to acrylic acid in a gas phase under heterogeneous catalysis, which is initiated in a reaction stage a starting reaction gas mixture comprising acrolein, molecular oxygen and at least one inert gas containing at least 20% by volume of molecular nitrogen, and comprising ε, C3H4 〇 molar ratio of 2 0.5 molecular oxygen and acrolein, carried on a fixed catalyst bed The fixed catalyst bed is set in two spatially continuous reaction zones A, B, the temperature of the reaction zone A is from 230 to 32 (the temperature in the range of TC, and the temperature in the reaction zone B is also in the range from 230 to 32 ( The temperature within the range of TC, the active composition of which is at least one multi-metal oxide comprising 7L of Mo and V, which is disposed in such a manner that the reaction zone A extends to a molar ratio of from 45 to 85 mol%. And when the initial reaction gas mixture passes through the whole fixed catalyst bedsheet process, the acrolein conversion rate is 9090 mol%' and the selectivity of the acrylic acid generated by the converted acrolein is 1% of the germline Initial reaction gas The time sequence in which the bulk mixture flows through the reaction zone corresponds to the alphabetical order of the reaction zone. [Prior Art] The foregoing method for catalytically oxidizing an acrylic road to acrylic acid in the gas phase is generally known (refer to 'for example, DE_A丨991 〇5〇8), and it is particularly useful as a second oxidation stage in the preparation of acrylic acid by two-stage catalytic gas phase oxidation starting from propylene. Acrylic is an important monomer, which itself or its alkyl group The form of vinegar is used to make it suitable, for example, as a binder: 0 In addition to molecular oxygen and reactants, the initial reaction gas mixture still contains inertia.

O:\91\9II69.DOC 1324994 The main reason for the gas is to keep the reaction gas outside the explosion range. - the heterogeneously catalyzed partial gas phase oxidation of acrolein to acrylic acid - the purpose of which is to obtain a reaction, the gas mixture is passed through the reaction zone under a predetermined boundary condition under a predetermined boundary condition, and the yield of the acrylic acid is relatively high. This is the number of moles of acrolein converted to acrylic acid based on the moles of acrolein used. The re-purpose of the heterogeneously catalyzed partial vapor phase oxidation of acrolein to acrylic acid is to achieve a relatively high space-time yield of acrylic acid* (STY Α) (in a continuous procedure, the fixation used in this system) The total amount of acrylic acid produced per liter of catalyst bed per hour). The hourly space velocity of acrolein from a fixed catalyst bed in the reaction stage at a constant given yield of γ ( (this means that the components of the initial reaction gas mixture are transported per hour through a fixed bed of 1 liter of fixed catalyst ( STP) = the amount of acrolein in liters (STP); the volume in liters will be the greater the amount of acrolein under standard conditions (ie, occupied by 25 〇 and i bar). Thus the teachings of the documents WO 01/36364, DE-A 19927624, DE-A ^ 19948248, DE-A 19948523, DE-A 19948241 and DE-A, 19910506 relate to a significant increase in propylene under substantially constant yaa. The hourly space velocity of the fixed catalyst bed in the reaction stage is substantially achieved by setting the fixed catalyst bed in the reaction stage in two spatially continuous temperature zones (reaction zones). The acrylic acid on the catalyst bed will be fixed. The mother hour space velocity is selected as g 150 liter (STP) / liter of fixed catalyst bed • hour, and the second (in the flow direction of the reaction gas mixture) temperature

The temperature of the O:\91\91I69.DOC 1324994 zone must be at least 丨0 higher than the temperature of the first temperature zone. Hey. EP-A 1106598 also teaches in a similar manner a high-load method for the heterogeneously catalyzed partial gas phase oxidation of acrolein to acrylic acid, wherein the fixed catalyst bed of the reaction stage is provided in a plurality of temperature zones. According to the teaching of EP_a 1 106598, the temperature difference in the subsequent temperature zone in the flow direction of the reaction gas mixture can be higher or lower than the temperature in the previous temperature zone, and EP-A 1106598 does not discuss at all what the situation should be. Use a larger or smaller temperature difference below. · ΕΡ·Α 1106598 does not mention the temperature or temperature zone of the reaction zone at all.

Relatively the rest of the prior art document defines the temperature of the reaction zone as the temperature of the fixed catalyst bed disposed in the reaction zone when the process is carried out in the absence of a chemical reaction. When the temperature is not constant in the reaction zone, the term temperature of the reaction zone means the (numerical) average of the temperature of the fixed catalyst bed along the reaction zone. The individual reaction zones should be heated substantially independently of one another such that a reaction zone always corresponds to a temperature zone. The definition of the temperature in the above reaction zone also applies to this document. Since the heterogeneous phase of the propylene road to the acrylic acid catalyzes a part of the gas phase oxidation is a remarkable exothermic reaction, the temperature of the reaction gas mixture passing through the fixed catalyst bed is generally different from the temperature of the reaction zone. It is generally higher than the temperature of the reaction zone and generally decreases in the reaction zone by a maximum (maximum heating point) or from a large value. However, the shortcomings of the 'first month' art teachings are that it is entirely oriented towards operating a multi-zone configuration at a higher propylene road load. This is a procedure that will inevitably

O:\91\91I69.DOC 丄J厶 is accompanied by the shortcomings of STY. However, this requires an appropriate market demand for acrylic acid. When there is no (for example, temporary) acrylic acid, the multi-zone configuration must be = low propylene is operated under load, and the subsequent pursuit of the target parameter is the relatively high acrylic acid generation selectivity (SAA) of the converted propylene road 4. The single pass of this system, the main conversion acrylic acid molar number The present invention is directed to providing a method for catalyzing a portion of a gas phase oxidation of a heterogeneously catalyzed portion of a C (C) to acrylic acid in a multi-zone configuration. Acrylic acid is produced at a relatively high selectivity under a 15 liter liter (STP)/liter liter of acrylic acid load. I have found that this purpose can be achieved by a gas phase in the absence of phase catalysis. The method for oxidizing a virgin berry to a (tetra) acid is carried out by reacting a starting reaction gas mixture (which comprises an propylene road, molecular oxygen, and an inert gas containing at least 20% by volume of molecular nitrogen to J) in a reaction stage, and Contains 〇2 c3H4o Mo The molecular oxygen and glyphosate of g0 5 are transported on the fixed catalyst bed ^. This catalyst bed is set in a continuous reaction zone A, B, and the temperature of the reaction zone A is from 23 〇. To 32 (temperature in the range of rc, and vice versa, the temperature in zone B is also in the range from 23 〇 to 32 〇. The temperature within the range, the active composition of which is at least - the oxidation of the metal containing the elements Mo and V The material is disposed in such a manner that the reaction zone A extends to a molar conversion ratio of 45 to 85 mol% and the propylene conversion ratio is when the initial reaction gas mixture passes through the entire fixed catalyst bed. %, and calculated by converted propylene road

O:\91\91I69.DOC -9- 1324994 The selectivity of propionate formation is 290% by mole. The time sequence of the initial reaction gas mixture flowing through the reaction zone corresponds to the alphabetical order of the reaction zone. a) The hourly space velocity of the two dilute aldehydes in the initial reaction gas mixture contained on the fixed catalyst bed is $ 145 liters (STP) of acrolein / liter of fixed catalyst bed · hour and $ 70 liter (STP) acrolein / liter Fixed catalyst bed·hour; b) fixed catalyst bed volume-specific activity is constant or increased at least once in the flow direction of the reaction gas mixture on the fixed catalyst bed; and c) from the highest temperature (which is the reaction gas mixture The difference TmaxA_TmaxB formed by the highest temperature in the reaction zone A and the highest temperature TmaxB, which is the highest temperature of the reaction gas mixture in the reaction zone B, is 〇. The volume-specific activity of the fixed catalyst bed is preferably increased at least once in the flow direction. In general, S, the difference in the method according to the invention TniaxA _ T〇iaxB will be no more than 75 °C. According to the present invention, Tn-A_TmaxBg3<t&s6〇<t is preferred. In the method according to the invention, TmaxB^5t and $4 are more excellent. According to the process of the present invention, for example, the hourly space velocity of acrolein in the initial reaction gas mixture contained on the fixed catalyst bed is $70 liters (STP) acrolein/liter·hour and $14 liter liter (STp). Acryl / liter • hour, or 270 liter (STP) acrolein / liter · hour and $ 135 liter (STP) acrolein / liter • hour, or $ 7 liter (STp) acrolein / liter · hour and $ 140 liter (STp Acrylaldehyde / liters / hour, or ^ 80 liters (STP) acrolein / liters / hour and $ 13 liters (sTp) acrolein / liters / hour, or ^ 90 liters (STP) acrolein / liters / hour, and

O:\91V9II69.DOC Helmet 125 liters (STP) acrolein / liters • hour, or g 1 liter (STp) acrolein / liter • hour and $ 120 liter (STp) acrolein / liter • hour, or ^ 105 Liters (STP) acrolein/liter·hour and $115 liter (STp) acrolein/liter·hour is advantageous. It should be understood that the hourly space density of acrolein in the reaction gas mixture contained on the fixed catalyst bed is <7 〇 liter (STP) acrolein/liter·hour and/or the volume of the fixed catalyst bed _ specific activity In the case of values, the method according to the invention can also be applied. However, the operation of the multi-zone configuration under this low reactant load will be extremely uneconomical.

When carrying out the process according to the invention, in one aspect, the temperature of the reaction zone eight and the temperature of the reaction zone B are both in the range from 23 〇 to 32 (rc, and on the other hand, in the temperature of the reaction zone B) The difference between (τΒ) and the temperature of the reaction zone a (τΑ), that is, TB - ΤΑ, system ^吖 and ^_1〇.〇, or ^〇〇c and, or, '·里常 S 0 C and 3 In the case of -3 C, the difference TmaxA_^pmaxB required in accordance with the invention is generally achieved. In other words, contrary to the prior art teachings on high loads, the temperature in the subsequent zone in the process according to the invention will generally be higher than the temperature in the previous reaction zone. When the temperature of reaction zone A is within the range of 25〇 to 3〇〇, or within the preferred range of 260 to 280 °C, the above statement regarding temperature difference Τβ_ Ta is also Suitable. The working pressure in the method according to the invention may be lower than atmospheric pressure (for example as low as 0.5 bar) or south to atmospheric pressure. Typically, the working pressure will be at a value from 1 to 5 bar, often from丨 to 3 bar. The reaction pressure will generally not exceed

O:\9l\91169.DOC -11- 100 bar. Roots. According to the invention, the reaction zone A extends to a molar conversion of acrolein from 50 to 85 mol% or from 6 to 85 mol%. In general, the acrolein conversion in a single pass in the process according to the invention may be from <92 mol%' or -94 mol%, or 296 mol. /. , or 298% by mole and often even ^99% by mole. The selectivity to acrylic acid formation will generally be <92% molar, or 294 moles/〇, often 2 95 mole % or ^96 mole % or g 97 mole %. According to the present invention, the oxime:: acrolein molar ratio in the starting reaction gas mixture must be g 〇·5. It is often tied to the value of $丨. Typically, this ratio will be at a value of ^3. According to the present invention, the oxime 2: propylene molar ratio in the starting reaction gas mixture will be from 1 to 2 or from 1 to 1.5.

A useful catalyst for the immobilized catalyst bed for catalytic gas phase oxidation of acrolein according to the present invention is that all of the active compositions thereof are at least one catalyst comprising a plurality of metal oxides of Mo and V. Such a suitable polymetallic oxide catalyst is available, for example, from US-A 3 775 474, US-A 3 954 855, US-A 3 89 395 1 and US-A 43 39355. Also particularly suitable are those of EP-A 427 508, DE-A 2 909 671, DE-C 3 151 805, DE-B 2 626 887, DE-A 430 299, EP-A 700 893, EP-A 714 870 and DE-A 19 736 515, and DE-A 10046928 Multimetal telluride composition. Exemplary embodiments of EP-A 714700 and DE-A 19736105 are also suitable herein. A multi-metal oxide active composition suitable for use in a fixed catalyst bed, such as the composition of DE-A 19815281, may be encompassed by the formula iv O:\91\91169.DOC -12· 1324994

Mo^VaX^X'eX'dX'eX'fX^On (IV) The variables are defined as follows: X!=W, Nb, Ta, Cr and/or Ce, X2=Cu, Ni, Co, Fe, Μη And / or Zn, X3 = Sb and / or Bi, X4 = - or a variety of alkali metals, X5 = - or a variety of alkaline earth metals, X6 = Si, A, Ti and / or Zr, a = 1 to 6, b = 0.2 Up to 4, c = 0.5 to 18, d = 0 to 40, e = 0 to 2, f = 0 to 4, g = 0 to 40, and n = valence and frequency of elements other than oxygen in IV The number determined. Preferred embodiments according to the invention in the active polymetal oxide IV are compositions encompassed by the definitions of the following general formula IV: X*=W, Nb and/or Cr, X2=Cu, Ni, Co and / or Fe, X3 = Sb, X4 = Na and / or K, X5 = Ca, Sr and / or Ba, X6 = Si, A1 and / or Ti, OA91VSU69.DOC -13- a = 1.5 to 5, b=0.5 to 2, c=0.5 to 3, d=〇 to 2, e=0 to 0.2, f=〇 to 1, and

The number determined by the frequency and frequency. Multi-metal oxide IV system formula 〇η· (V) M〇12Va'Y1b, Y2c, Y5f (Y6 where S w Y = W and / or Nb, Y2 = Cu and / or Ni, Y5 = Ca and / Or Sr, Y6=Si and/or Ab a'=2 to 4, b'=l to 1.5, c,=l to 3, f'=〇 to 0.5, g'=〇 to 8, and η·= The number determined by the valence and frequency of the elements other than oxygen in V. Suitable polymetallic telluride compositions (1V) according to the invention may be known per se (for example as disclosed in DE-A 4335973 or ΕΡ-Α) 714700)).

O:\91\91169.DOC -14- In general, the active composition suitable for immobilizing the catalyst bed, especially the composition of the compound I#诵-polymetallic oxide 八八式1¥, can be obtained from its elements The core is prepared from a non-::: sound that has a composition corresponding to its stoichiometry to finely divide the preferred dry mixture, and to apply it at 350 to 60. C ▲ degree calcination, and simple ~ flat 9.7 million styles prepared #. Calcination can be carried out in an inert φ emulsified atmosphere, such as air (a mixture of inert gas and oxygen) and in reducing the atmosphere (such as inert gases and reducing gases such as Hr ΝΗ:, CO, methane and 'or C. or other previously mentioned In the heart of the reducing gas). The calcination time can vary from a few minutes to a few hours, and it typically decreases with k > summer. More often, it is an elemental component of the active metal halide active composition Iv. Useful sources include compounds which have been oxides and/or compounds which can be converted to oxides by heating at least in the presence of milk. The compound for the preparation of the multi-metal oxide composition can be intimately mixed in a dry, wet form. When it is mixed in a dry form, the starting compound is preferably used as a finely divided powder, and calcined after mixing and non-essential densification. "It is preferred to achieve intimate mixing in a clear state. It is typically carried out by forming the starting compound in the form of an aqueous solution and/or suspension." When the starting material is completely in the form of a dissolved element, the source of the knife is 4'. The solvent used to prepare the especially fine dry mixture in the mixing method described is preferably water. The dried aqueous drying process is then preferably carried out by spray drying the aqueous mixture at an outlet temperature of from (10) to 15 passages. The resulting multi-metal oxide composition, especially a composition of the general formula, which is generally used in a powder form in a fixed catalyst bed, and is formed into

O:\9l\9U69.DOC •15-1324994 Special 1 catalyst form' and this can be formed before or in the final calcination of the active composition from the powder form or its un-body, d via Adding an auxiliary agent, for example as a lubricating graphite or stearic acid and/or a shaping aid and a strengthening agent such as glass, stone 2: cut or titanate unloaded microfibers, to densify into a desired catalyst form (for example, via a chain Or extrusion) to prepare a catalyst without support. Examples of suitable support catalyst bodies are outer diameters and lengths of 2 m millimeters: solid 0 cylinders or hollow cylinders. In the case of a hollow cylinder, the wall thickness is preferably 1 to 3 mm. It is understood that the support catalyst may also have a spherical shape, and the sphere may have a diameter of from 2 to 10 mm. It is understood that the powdery active composition still to be calcined or its powdered precursor electronic body can also be formed by application to a preformed emotional catalyst support. The coating of the support to prepare the coated catalyst is generally carried out in a suitable rotatable container as disclosed, for example, in DE-A 29〇9671, ΕΡ·Α 293859 or EpA 714. For coating the support, it is preferred to wet the powder composition to be coated and to dry it again after coating, for example using hot air. The layer thickness of the coating is preferably selected from the group. It is preferable to be in the range of from 50 to 500 μm and preferably from 15 () to 25 μm. Useful support materials are conventional porous or non-porous alumina, cerium oxide, cerium oxide, dioxins, cerium carbide or cerium salts such as magnesium citrate or aluminum silicate. The support may have a regular or irregular shape, although a regular shape carrier having a significant surface roughness, such as a sphere having a coarse sand layer or a hollow circle O: \91\91I69.DOC -16· 1324994, preferably a column. A spherical support having a non-porous, rough surface on the shellfish prepared from a talc (e.g., Steatite C220 available from CeramTec) having a diameter of from 1 to 8 mm, preferably from 4 to 5 mm, is suitably used. However, suitable supports also include cylinders having a length of from 2 to 10 mm and an outer diameter of from 4 to 1 mm. In the case of a ring as a support, the wall thickness is typically from 1 to 4 mm. The preferably used annular carrier has a length of 2 to 6 mm, 4 to 8 mm outside and 1 to 2 mm. The wall is thick. A suitable carrier is in particular a ring of 7 mm X 3 mm X 4 mm (outer diameter x length X inner diameter). It is understood that the fineness of the catalytically active oxide composition applied to the surface of the support will be suitable for the desired coating thickness (see EP-A 714 700). An advantageous multimetal oxide active composition using a catalyst as a fixed catalyst bed is also a composition of the formula VI [D]p[E]q (VI) wherein the variables are defined as follows: D = M〇i2Va"Z^ b"Z c"Z^d'>Z^e"Z^f»Z^g"〇x" * E= Z7i2Ciih"Hi"Oy" 1 Z^W, Nb, Ta, Cr and/or Ce, Z2=Cu, Ni, Co, Fe, Μη and/or Zn, Z3=Sb and/or Bi, Z4=Li, Na, K, Rb, Cs and/or Η, Z5=Mg, Ca, Sr and/or Ba, Z6=Si, A1, Ti and/or Zr, Z7=Mo, W, V, Nb and/or Ta 'with Mo and/or W, the best is a"=l to 8

O:\91\91I69.DOC -17- 丄b"=0.2 to 5, c”=0 to 23, d"=0 to 50, e"=〇 to 2, f"=0 to 5, g”= 0 to 50, h"=4 to 30, iM = 0 to 20, and X", y', = the number determined by the price of 1 element and the frequency of the element other than oxygen in the VI, and p, qp The /q ratio is a number other than zero from 160:1 to 1:1, and it can be finely divided into a morphological composition by a multi-metal oxide composition E Z7i2Cuh"Hi"〇y» (e) Individual preforming, and then will be pre-formed

Formed solid starting composition! Add people to include expectations? , compared to the source of the elements Mo, V, Z1, Z2, Z3, Z4, Z, Z of the aforementioned elements of the stoichiometric DM〇12Va"zVz2c"Z3d"Z4e"zVz6g" (D) (starting composition 2) The aqueous mixture may be dried in an aqueous solution, an aqueous suspension or a finely divided dry mixture, and the dried precursor composition is calcined at a temperature of 250 to 600 ° C before or after drying to obtain a desired catalyst form. And made. Preferably, the preformed solid starting composition is added to the multimetal oxide composition VI in the aqueous starting composition 2 at a temperature of the working temperature.

O:\91\91I69.DOC -18- 1324994

A detailed description of the preparation of the oxide VI catalysts is contained in, for example, EP-A 668,104, DE-A 19,736, 050, DE-A 100, 469, 228, DE-A 19, 740, 493, and DE-A 19,528,646. With regard to forming, the statements made with respect to the multimetal oxide IV catalyst are also applicable to the multimetal oxide VI catalyst. A more suitable multimetal oxide composition of the catalyst as a fixed catalyst bed is the composition of DE-A 19815281', in particular from all of the exemplary embodiments of this document. Regarding the forming, the same applies as described above. With regard to the fixed catalyst bed according to the process of the invention, a particularly suitable catalyst system DE-A 4442346 coated catalyst S1 (stoichiometric: MouVsWuCuuOn) and S7 (stoichiometric:

Ni〇.8〇n) having a ratio of active composition of 27% by weight and a coating thickness of 230 μm; coated catalyst of Preparation Example 5 of DE-A 10046928 (stoichiometric: 20% by weight) Active composition ratio; coated catalysts of Examples 1 to 5 of DE-A 198 15281, but also coated catalysts of the aforementioned second reaction stage to 7 mm X 3 mm X 4 mm (outer diameter x length X) a support ring of the inner diameter) having a weight percent active composition ratio (based on the overall composition of the coated catalyst); and prepared according to DE-A 19736105, and having a coating to the aforementioned 7 mm X 3 mm X 4 The coated catalyst of the phase active composition is a ratio of 2% by weight of the active composition of the millimeter support to ^^^ff*(Mo10.4V3W1.2〇x)(CuMo〇.5W〇.5〇4). When the factors remain unchanged, except that the shape of the body is changed to 5 mm χ 3 mm X 1.5 mm (outer diameter X length x inner diameter), the above recommendation is given according to the present invention: 0: ^1^1169.000 -19- The catalyst used in the reaction stage of 1324994 is only suitable for the reaction stage according to the invention. The multimetal oxides described can also be used in the reaction stage according to the invention in the context of the unsupported catalyst ring. In order to prepare a fixed catalyst bed in the process according to the invention, it is possible to use only active multi-metal oxide active compositions. Forming the catalyst body, or using a shaped catalyst body having a multimetal oxide active composition and its behavior for gas phase oxidation of the heterogeneously catalyzed portion is substantially inert and does not have a multimetal oxide active composition A homogeneous homogeneous mixture of shaped bodies (formed dilute bodies). Useful materials for such inert shaped bodies generally include all such materials which are also suitable as coated materials for coated catalysts in accordance with the present invention. Such useful materials include, for example, porous or non-porous alumina, ceria, ceria, cerium oxide, cerium carbide, cerium salts such as magnesium citrate or aluminum citrate or have been mentioned above Block talc (for example, from CeramTec^ Steatit C 22〇). The shape of such an inert shaped dilute body is generally visible. In other words, it may be, for example, a sphere, a polygon, a solid cylinder or a ring. In accordance with the present invention, it is preferred that the shape of the selected inert shaped dilute body conforms to the shaped catalyst body to be diluted therewith. According to the invention, the chemical composition of the active composition used is preferably unchanged on the fixed catalyst bed. In other words, although the active composition for a single shaped catalyst body can be a different polymetal comprising an elemental core and a mixture of oxides, but the same mixture must be used for all shaped catalyst bodies of the fixed catalyst bed. In this case, the volume-to-ratio can be reduced in a simple manner (ie normalized to single

O:\91\91169.DOC -20- 'product> a /· Raw, for example, a basic amount of a shaped catalyst body prepared by diluting the body by a dilution of the formed body. The activity of a substance and catalyst contained in a specific bed volume is lower every time the case is returned. Therefore, the addition of at least a second volume specific activity in the flow direction of the reaction gas mixture on the fixed catalyst bed can be achieved in a simple manner for the method according to the invention, for example, a sentence of ten * a, two by a type The shaped catalyst in this proportion of inert shaped dilute body starts the bed, and the flow direction = continuous or at least - times or more than - suddenly (eg, stepwise) lowers the volume of the shaped body. Eclipse. " 'Also, by applying a right-form and active composition type of M to the right _,, two coating forming catalyst body, to increase the thickness of the active composition layer applied to the support, increase thickness or In the mixture of coated catalysts having the same shape but having a weight ratio of different active compositions, the proportion of the shaped colloidal agent which is increased by the content of the higher active composition is increased, and the volume-specific activity is increased. The active composition itself is added to the active personal product of the starting compound to be calcined by adding, for example, an inert diluent material such as a refractory gas to oxygen during the preparation of the active composition. Dilution. Adding different amounts of diluted material naturally produces different activities. The more dilute the added material, the lower the activity will increase. It can also be, for example, a non-supported catalyst and a coated catalyst (see π, In a mixture of the same active composition), a similar effect is obtained by changing the mixing ratio in an appropriate manner. It is also possible to combine the variables described in the description. Using catalysts having different chemical compositions of the active mixture of 'and therefore' these different compositions having different live on a fixed catalyst bed

0; V9I\91169.DOC • 21- 1324994 sex. These mixtures can be further diluted in an inert dilution body. The volume-specific activity will generally not be reduced once in the flow direction of the reaction gas mixture in the fixed catalyst bed in the process according to the invention. A bed consisting entirely of inert material (eg, only a fixed dilution body) may be disposed upstream and/or downstream of the fixed catalyst bed (in this document, since it does not contain a shaped body having a multi-metal oxide active composition, It is therefore not included in the fixed catalyst bed based on the terminology). The shaped dilute body used in the inert bed can have the same shape as the shaped catalyst body used to immobilize the catalyst. However, the shaped body of the shaped body used in the inert bed may also be different from the body of the shaped catalyst body described above (e.g., 'spherical rather than toroidal). The shaped body used in such an inert bed often has a ring-shaped body of 7 mm χ 7 mm X 4 mm (outer diameter X length X inner diameter) or a spherical shape having a diameter d = 4_5 mm. According to the present invention, in the flow direction of the fixed catalyst bed in the reaction gas mixture according to the method of the present invention, the structure is preferably as follows: First, the total length of each of the fixed bed catalyst beds is from 1 〇 to 6〇%, from 1 〇 to 50% is preferred, 20 to 40% is more preferred, and 25 to 35% is the optimum length (i.e., a length of 0.70 to 1.50 meters, preferably 〇.9 〇 to 12 〇 is preferred) is a shaped catalyst body. And a homogeneous mixture of the shaped dilute body (both having substantially the same shape) or two (with decreasing dilution) continuous homogeneous mixture, wherein the weight ratio of the shaped body to be diluted (formed catalyst body and shaped dilute body) The mass density is generally only slightly different) generally from 1 to 5 weight percent, preferably from 20 to 45 weight percent, and more preferably from 25 to 35 weight percent.

O:\91\9U69.DOC -22- 1324994 According to the present invention, the end of the length from the first zone to the fixed catalyst bed (i.e., the length of 2.00 to 3.00 m, preferably 2, 50 to 3. _) Preferably, it is preferred to dilute to the bed of the shaped catalyst body which is more than (four) degrees (compared to the first zone) or the unformed bed of the same shaped catalyst body which is also used in the first zone. The foregoing description is particularly applicable when the shaped catalyst used in the fixed catalyst bed is a coated catalyst ring or a coated catalyst sphere (especially as listed herein as preferred). Based on the foregoing configuration, the shaped catalyst body or its support ring and the shaped dilute body in the method according to the invention have substantially a ring shape of 7 mm x 3 mm χ 4 mm (outer diameter X length X inner diameter) body. While substituting the inert shaped dilute body, the active composition is used at a level that is 2 to 15 weight percent lower than the amount of the active composition of the shaped coated catalyst body at the end of the fixed catalyst bed 2. The foregoing description also applies. The reaction stages of the process according to the invention can be carried out in an advantageous manner from the application point of view in a two-zone tube bundle reactor as described, for example, in DE-A 19910508, 19948523,19910506 and 19948241. A preferred variant of the two-zone tube bundle reactor which can be used in accordance with the present invention is disclosed in DE-C 2830765. However, the two-zone tube bundle reactors disclosed in DE-C 2513405, US-A 3147084, DE-A 2201528, ΕΡ-Α 3 83224 and DE-A 29032 18 are also suitable for carrying out the reaction stages of the process according to the invention. In other words, the fixed catalyst bed (possibly with a downstream and/or upstream inert bed) used according to the invention is arranged in the simplest manner in a metal tube of the tube bundle reactor O:\91\91169.DOC • 23-1324994, And the heating medium that separates the two spaces, generally is a salt melt, a core, and a base metal g. The tube section extended by the particular salt bath exhibits a reaction zone according to the invention. In other words, in the simplest manner, for example, the salt bath A is flowed around the tube section (reaction zone A), wherein the propylene is oxidatively converted (in a single case, Up to (iv) a conversion value in the range of 45 to 85 mol% (preferably (10) to 85 mol%, more preferably 60 to 85 mol%), and flow of the salt bath (four) around the pipe section (reaction zone b) , wherein acrolein is then oxidatively converted (in a single pass) until a conversion value of at least 9 moles per mole is reached (if desired, it can be followed by other reaction zones A, B used in accordance with the invention) Reaction zone at individual temperatures. From the point of view of application, it is advantageous for the reaction stage according to the process of the invention not to include other reaction zones. In other words, it is preferred to have the salt bath 3 flow around the pipe section, followed by oxidation of acrolein. (in one way) up to 292% by mole, or $94% by mole, or ^96% by mole or 298% by mole and often even more than g99 mole%. Typically, the temperature zone B begins to exceed The maximum heating point of temperature zone A. According to the present invention, the salt baths A, B can be transported in the same direction or countercurrent to the space surrounding the reaction tube with respect to the flow direction of the reaction gas compound flowing through the reaction tube. It is clear that according to the present invention, the same can be applied in the reaction zone A Flow flow, and application of countercurrent flow in reaction zone B (or vice versa). In all of the foregoing cases, it is apparent that a lateral flow can be overlapped with the salt melt relative to the reaction tube occurring within a particular reaction zone. In parallel flow, the individual reaction zones correspond to a tube bundle reactor as described in Ep_A 7007 14 or EP-A 700893, which generally results in a heat exchange medium in the longitudinal section O:\91\9U69.DOC -24-1324994 By means of a tortuous flow side of the catalyst tube bundle. Typically the catalyst tube used in the reaction zone according to the invention in the aforementioned two-zone tube bundle reactor is made of ferrite steel and typically has 1 to The wall thickness of 3 mm. The inner diameter of the wall is generally from 2 to 3 mm, often from 22 to 26 mm. The length is preferably from 3 to 4 m, preferably 3.5 m. Fixed catalyst bed At least 60%, or at least 75%, or at least 9% by weight of the length of the zone. Any remaining length may be occupied by an inert bed as desired. From the application point of view, the number of catalyst tubes contained in the bundle container is preferably at least 5,000, preferably at least 10,000. The number of catalyst tubes contained in the reaction vessel is often from 15 to 3 Torr. The tube bundle reactor with more than 40,000 catalyst tubes is usually an exception. In the vessel, the catalyst tubes are generally evenly distributed (preferably 6 adjacent tubes per catalyst tube) and preferably distributed in such a way as to provide a distance between the axes of the centers of the catalyst tubes ( The catalyst tube pitch is from 35 to 45 mm (see, for example, EP-B 468290). Useful heat exchange media are, in particular, fluid heating media. It is especially advantageous to use a melt such as potassium nitrate, potassium nitrite, sodium nitrite and/or sodium nitrate or a low melting point metal such as sodium, mercury and alloys of different metals. In general, in all of the foregoing flow configurations in the two-zone tube bundle reactor according to the reaction stage of the present invention, the flow rate required in the two heat exchange medium circuits is selected such that the temperature of the heat exchange medium self-enters The inlet from the reaction zone to the exit from the reaction zone was raised to 15 °C. In other words, according to the present invention, the aforementioned ΔΤ can be from 1 to 1 〇. (:, or from 2 to, or from 3 to 6. 〇. According to the invention, the inlet temperature of the heat exchange medium entering the reaction zone A is O:\9I\91I69.DOC -25· 1324994 is generally in the range of 230 to In the range of 320 ° C, preferably in the range of 250 to 300 T: and more preferably in the range of 260 to 280 ° C. According to the present invention, the inlet temperature of the heat exchange medium entering the reaction zone B is also the same. It is in the range of 23 〇 to 28 〇, but according to the present invention, it is generally lower than the inlet temperature of the heat exchange medium entering the reaction zone A by g (TC to Slot, or, or often g 〇 °C and. At this point it is again indicated that in order to carry out the reaction stage according to the process of the invention, in particular the two-zone tube bundle reactor type described in DE-B 2201528 can be used, which comprises moving a heat exchange medium which is part of the reaction zone B to a higher temperature. Zone A 'heats the cold start reaction gas mixture or cold cycle gas as needed. The tube bundle characteristics in individual reaction zones can also be constructed as described in Ep_A 382 〇 98. The method according to the invention is generally used via Acrolein prepared by catalytic gas phase oxidation of propylene. In general, the acrolein-containing reaction gas system for propylene oxidation is used without intermediate purification, which is why the starting reaction gas mixture according to the present invention may also contain a small amount, for example, unconverted dilute or propylamine. By-product of oxidation. It is also generally necessary to add the oxygen of the propylene oxidation to the product gas mixture of propylene oxidation. This is the catalytic oxidation of propylene to acrolein in the gas phase before the process according to the invention. Preferably, in a manner similar to the method according to the invention, in the following manner, the starting reaction gas mixture /, 3 propylene, molecular oxygen and at least one inert gas are used in a reaction stage, and Including 〇: Moerby>! The eight industrial products 3 6 ^ ~ <Knife oxygen and propylene) are transported on a fixed catalyst bed, and the solid-catalyzed bed is in two spatially continuous reaction zones A, B, and Reaction zone

O:\91\9U69.DOC -26- 1324994 A1 is at a temperature ranging from 290 to 380 ° C, and reaction zone B is also at a temperature ranging from 290 to 380 ° C, and The active composition is at least one multi-metal oxide comprising the elements Mo, Fe and Bi in a manner such that the reaction zone A' extends to a propylene conversion from 40 to 80 mol% and passes through a fixed catalyst bed. The one-pass propylene conversion rate of 1 is $9 〇mol. /〇, and the accompaniment and the by-product selectivity of the acrylic by-product are 290 mol%, wherein a) the space velocity per hour of propylene contained in the starting reaction gas mixture on the fixed catalyst bed is $160. Liter (STP) propylene/liter fixed catalyst bed 1 hour and $90 liter (STP) propylene/liter fixed catalyst bed 1 hour; b) fixed catalyst in the flow direction of the reaction gas mixture on the solid catalyst bed The volume-specific activity of the bed is constant or increased at least once; and c) from the highest temperature TmaxA_ (which is the temperature of the reaction gas mixture in reaction zone A, the highest temperature) and the highest temperature TmaxB' (which is the reaction gas mixture The difference formed by the highest temperature in the reaction zone is ΧΑ^ΧΑ·_ TmaxB. In general, the difference TmaxA__TmaxB' will be no more than 80 °C.

TmaxA' - TmaxB, 3 °C and ‘70 °C are preferred. TmaxA. - TmaxB, 2 (TC and S60 ° C are optimal. It has been confirmed that the hourly space velocity of propylene contained in the initial reaction gas mixture on the fixed catalyst bed is 2 90 liters (STP) propylene / liter·hour and S 155 liters (STP) propylene / liter • hour, or $ 1 liter (STp) propylene / liter • hour and 彡 15 liters (S1T) propylene / liter • hour, or 2110 liter (STP) propylene / liter • Hours and $145 liters (STP) propylene/gong O:\91\91169.DOC -27- ^24994 liters j or g 120 liters (STP) propylene/litre hour and g 140 liters (STP) gamma/ Liters per hour or 25 liters (STp) propylene / liters • hours and S135 liters (STP) propylene / liters · hours is beneficial. When the method is carried out, when in the aspect, the reaction U, the temperature and the reaction zone π The temperature is between 290 and 380. (in the range, and on the other hand, the difference between the temperature in the reaction zone B' (Τβ') and the temperature in the reaction zone A, (Ta,), ie, or In each case, or often ^ C and g -3 C, the required difference TmaxA. _ TmaxB. is generally achieved. In other words, when carrying out the method according to the invention, Two two-zone tube bundle reactors are connected in series or combined into a four-zone tube bundle reactor, as illustrated, for example, in w〇01/36364 'and can perform propylene oxidation in the first two-zone portion' and second The acrylaldehyde oxidation according to the present invention is carried out in two portions. In the first case, the internal bed is generally disposed in the two reaction stages, and the catalyst bed is also H. The propylene oxide oxide can also be a zone tube bundle reactor which is separated from the subsequent propylene oxidation oxidation stage or combined with it in an appropriate manner. In the case of combination, the length of the reaction tube in many cases Is equivalent to the sum of the lengths of the unbound tube bundle reactor. The propylene content in the S-reaction gas mixture in the reaction stage prior to the process according to the invention may be, for example, a value of 4 to 15% by volume, often 5 to 12 % by volume, or 5 to 8% by volume (in each case in total volume). The method before the method according to the invention will often be 丄:. to 3.〇): (5 to 25), to 1: (1.4 to 2.3): (1〇 to 15) is preferred In the beginning

O:\91\91169.DOC •28-1324994 The propylene: oxygen: inert gas (including steam) volume ratio in the gas mixture. In general, at least 2% by volume of the inert gas will be from the molecule n, or from _% by volume, or (iv) vol%, or wo volume, m6G vol%, or (four) vol%, or (9) vol% , or $90% by volume' or $95% by volume of molecular nitrogen (in this document, an inert diluent gas - generally means less than 5% in a single pass through a particular reaction stage, preferably less than 2% A gas that is converted; in addition to molecular nitrogen, it is, for example, a gas such as (four), bis-n, butyl, C 〇 2, CO, steam, and/or gas. Of course, the inert diluent gas in the process prior to the reduction of the process of the invention may also consist of up to 5 G mole %, or up to 75 M mole % or more. The other composition of the diluent gas may also be a recycle gas remaining after the acrylic acid is removed from the product gas mixture of the process according to the invention. a useful catalyst for the oxidation of the catalyst propylene in the gas phase, especially

Catalysts of EP-A 15565, EP-A 575 897, DE-A 19746210 and DE_A 19855913. The acrolein content in the starting reaction gas mixture in the process according to the invention is, for example, from 3 to 15% by volume, often from 4 to 1% by volume, or from 5 to 8% by volume (in each case in total volume) meter). The method according to the invention will often be at 1: (1 to 3) · (0 to 20): (3 to 3 〇), to 1: (1 to 3): (〇·5 to 1 〇) : ( 7 to 10) are preferably carried out in the propylene chain in the starting reaction gas mixture: oxygen: steam: inert gas volume ratio (liters (STP)). However, it is understood that the method according to the invention can also be found in: (〇9 to 13): (2 $

O:\91\91169.DOC -29- 1324994 to 3 ·5) : (10 to 12) acrylonitrile present in the initial reaction gas mixture: oxygen: steam: volume ratio of other gases (liters (STP) )) Under proceed. The multimetal oxide composition of DE-A 10261186 is also used at this time as an advantageous active composition for the immobilized catalyst bed according to the process of the invention. A preferred embodiment according to the invention for a two-zone tube bundle reactor for the partial oxidation stage of propylene prior to the reaction stage according to the invention may have the following configuration (the detailed configuration of the configuration may be as in the novel application 2 〇 2 19,2002 19 278.4 and 202 19 279.2 or PCT application PCT/EP02/14187, PCT/EP02/14188 or PCT/EP02/14189): Catalyst tube: Material of catalyst tube: Fertilizer iron steel; Catalyst d Size of the official: length, for example, 3,500 mm; outer diameter, for example, 30 mm; mesh: for example '3G'_' or 28, _, or formula (iv) most, up to 10 in the same way as the catalyst tube S7 783Γ 7 Thick, two; as described in 12 70 _", for example, 'the same length and wall thickness of the pole, for example, the outer diameter of 33 4 mm and the wall heat such as the center of the well and, for example, the thickness of the wall; the outer diameter of the water Reactor (the same material as the catalyst tube): Plating thickness: cylindrical container with a few millimeters of inner diameter 6, 〇〇〇 _8,00 〇 mm; reactor hood with electroplated 1.4541 stainless steel

O:\91\9U69.DOC -30· 1324994 m; a tube bundle set in an annular shape, for example, a diameter having a free central space free center space: for example, 1,000-2,500 mm (for example, millimeters, or 1,400 mm' or 1,600 mm, or 18 mm, such as 1,200, or 2,000 mm' or 2,200 mm' or 2,400 mm in one of the bundles of equilateral triangles (6 equidistant adjacent tubes per catalyst tube) , the distance between the inner shaft of the catalyst tube): 35-45 mm, ); the uniform uniform distribution of the catalyst tubes is mm, or 40 mm, or 42 mm, or 44 mm; the pitch of the tube is 1 (close to the catalysis, for example 36 mm, Or the end of the 38 catalyst tube is fixed and sealed in the catalyst tube sheet (the upper plate and the lower plate each have a thickness of ', for example, UK)-·m), and the upper end thereof is open to be bonded to the inlet having the initial reaction gas mixture In the hood of the container; the separator 1 disposed at, for example, the thickness of the half of the catalyst tube is 2 〇 _ι 〇〇 mm. The reactor space is symmetrically divided into two reaction zones (temperature zone) A' (upper zone) And B' (lower area); each reaction The deflecting plate is divided into two equidistant longitudinal sections; the deflecting plate has a ring-shaped body; preferably, the catalyst tube is fixed and sealed to the separating plate; it is not fixed and sealed to the deflecting plate, so the salt melt in a zone The lateral flow rate is rather strange; each zone has a salt melt as its heat carrier from its salt pump; a feed system of salt melt, such as 'below the deflector' and its removal system, such as a deflector Above; the tributary '$如' is removed from the two-salt melt circuit and, for example, cooled in a _ string or two other indirect heat exchangers (steam generation);

O:\9I\91169.DOC •31- 1324994 In the first case, the cooled salt melt stream is separated, combined with a specific residue machine, and pressurized by a specific pump to separate the salt melt around the container. In a suitable annular passage of the body; the salt melt reaches the tube bundle via a window disposed in the jacket of the reactor; the flow system 'e.g., in the radial direction to the bundle; in each zone, the salt melt surrounds the deflection The catalyst tube flow as determined by the plate 'e.g. in the following order • from the outside to the inside, - from the inside to the outside; the salt melt flows through the window surrounding the device around the vessel and in the annular channel surrounding the reactor jacket The ends of each zone are pumped in a circuit comprising a tributary cooling; the salt solution is passed through the reaction zones from bottom to top. The reaction gas mixture exits the reactor according to the reaction stage of the present invention at a temperature several degrees higher than the salt bath inlet temperature of the first reactor. For further processing, it is preferred to cool the reaction gas mixture from 220 ° C to 280 ° C in a separate aftercooler connected downstream of the reactor, preferably from 24 (rc to 260 ° C. The cooler is generally disposed below the lower tube sheet with a flange, and is generally composed of a tube of ferrite iron steel. It is preferable to introduce a partially or completely wound stainless steel sheet metal spiral into the aftercooler. In the interior of the tube to improve heat transfer. Salt melt: The salt melt used may be 53% by weight potassium nitrate, 40% by weight sodium nitrite

q;\91\9U69.D〇C 1324994 and a mixture of 7 wt% sodium nitrate; the two reaction zones and the aftercooler are preferably salt spurs using the same composition; in the reaction zone, by circulation pumping The amount can be about 1 每 per cubic metre, 〇〇〇 cubic meters / hour. Flow Control'· The starting reaction gas mixture preferably flows from the top to the bottom through the reactor, while the salt melts with different temperatures in individual zones are preferably transported from the bottom to the top; catalyst tubes and heat pipe feeds (from top to bottom) Bottom), for example: Segment 1: A hard talc ring of 50 mm in length as the initial bed of 7 mm x 7 mm x 4 mm (outer diameter and length X inner diameter). Section 2: Hard talc ring of length 140 cm 3 〇 〇 / 亳 5 x x 3 mm χ 2 mm (outer diameter χ length 内径 inner diameter) and 7 〇% by weight of no-support catalyst from section 3 The catalyst mixture of the homogeneous mixture is fed. Section 3: Length of 160 cm According to the ring of Example 1 of DE-A 10046957 (5 mm χ 3 mm χ 2 mm = outer diameter χ length χ inner diameter) catalyst support without support catalyst (stoichiometry: [Bi2w2〇9x2w 〇3]〇5 [M〇12C〇5.5Fe2.94Si159K〇.08〇x]1) 形态The shape of the two-zone tube bundle reactor which is advantageously used in the reaction stage of the acrylic road according to the present invention can be designed according to the present invention. As follows: Each factor is white as a two-zone tube bundle reactor in the propylene reaction stage. However, the thickness of the catalyst tube plate below is often 100-200 mm, for example,

O:\91\9II69.DOC -33- 1324994 110 mm, or 130 mm, or 15 mm, or 17 mm or 19 mm. The aftercooler is S; otherwise, the lower nozzle of the juxtapatic tube is open to the lower end of the outlet to the vessel, and the exhaust hood having the outlet of the product gas mixture, the upper reaction zone zone A, and the lower reaction zone zone B. Preferably, there is a means for supplying compressed air between the outlet "post-cooling device" and the inlet "reactor according to the reaction stage of the present invention". Catalyst and heat pipe feed (from top to bottom) can be, for example, as follows: Section 1: Length 20 cm · 7 mm 初期 7 mm χ 4 mm (outer diameter X length X inner diameter) shaped hard talc ring. Paragraph 2: Length 90 cm

3 〇 weight. /. 7 mm χ 3 mm χ 4 mm (outer diameter χ length X inner diameter) shaped hard talc ring and 70% by weight from section 4 section 3: Catalyst addition of a homogeneous mixture of coated catalysts. a hard talc ring of a length of 50 cm by weight of 5 mm "mm χ 4 mm (outer length χ inner diameter) and 8% by weight of the catalyzed mixture of the uniform mixture of the coated catalyst Adding. Section 4: Length 190 cm Low pass one of the ring of the preparation example 5 (7 mm X 3 mm X 4 mm = outer diameter x length χ inner diameter) coated catalyst catalyst (chemical 昼 #旦" W化... ten miles .M〇12V3W】.2Cu2 4〇x)c or 'Propylene stage catalyst tube and 埶 ★ ★ 赶 且 士 士 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及 及

O:\9l\9U69.DOC •34- 1324994 paragraph 1: length 50 cm as the initial bed 7 mm χ -ν . λ house rice χ 4 mm (outer diameter and long section 2 degrees Χ inner diameter) shaped hard talc ring. 300 cm in length according to DE-A 10046957 眚尬3 实施 Example 1 ring (5 mm χ 33⁄4 m χ 2 mm = outer 栌 ^ length X inner diameter) catalyst catalyst without support catalyst (chemical 讣詈 • "Mr予.十里.[Bi2W2〇9x2W〇3]05 ^ [M〇i2C〇5.6Fe2.94Sii59K〇〇s〇xL). The propylene phase catalyst tube and the top of the crucible to the bottom): 'Gaco can also have the following Appearance (from paragraph 1: length 20 cm as the initial bed of 7 1/2 card X 7 house m x 4 亳 m (outer diameter 兀 length χ inner diameter) shape of the hard talc ring. Segment 2 length 140 cm 25% by weight 7 Quartz γ 2 立, 卜 _ 卜 χ χ 4 mm (outer diameter χ length χ only) hard talc ring of the open body and 75% by weight of the catalyst mixture from the uniform mixture of the coated catalyst 3 190 cm in length, according to the preparation of Example 5 of DE-A 10046928, the ring 'mm Χ 4 耄 m = outer diameter χ inner diameter) coated catalyst catalyst (stoichiometry: M〇i2v3Wi 2 Cll2.4〇x ). In all of the propylene feeds mentioned, the following catalysts can also be used to replace the unsupported catalyst from the example of DE-A 10046957:

O:\91\9I169.DOC • 35-1^^4994 a) A catalyst according to Example lc of EP-A 15565 or prepared according to this example, except that it has the active composition M〇i2Ni6 5Zn2Fe2BiiPQ 〇(5) Κ〇· 〇6〇χ · 10 Si〇2 catalyst; b) DE-A 19855913 embodiment No. 3 shape 5 mm χ 3 mm χ 2 mm or 5 mm X 2 亳 m X 2 mm non-support hollow cylinder a catalyst; a non-supported multimetal oxide engineering catalyst according to the example of DE-A 19746210; d) one of the coated catalysts i, 2 and 3 of DE-A 10063162, except that they are identical The coating thickness is applied to a support 5 mm χ 3 mm X 15 house or 7 mm X 3 mm X 1.5 mm; e) coated catalyst according to the embodiment of DE-A 19815281, except that it is coated identically The layer thickness is applied to the support ring of 7 mm χ 3 mm χ 4 mm or 8 mm X 6 mm X 4 mm (always the outer diameter χ length χ inner diameter is listed above, the carrier material used is purchased Hard talc (C220) from CeramTec is preferred. In all of the foregoing acrolein stage feeds according to the invention, Substituting the coated catalyst according to Preparation Example 5 of DE A 10046928: a) a coated catalyst 31 having a weight of 27% by weight of active composition and a coating thickness of 23 μm of DE-A 4442346; 57; b) The coated catalysts of Examples 1 to 5 of DE 19815281, except that they have a content of 20% by weight of active composition, are applied to a support ring of 7 mm X 3 mm x 4 mm; Ο according to DE-Al97361〇5, And having a content of 20% by weight of the active composition applied to the aforementioned 7 mm η mm X 4 mm support having the chemical O: \9I\9H69.doc -36 - 1324994. A coated catalyst of a biphasic active composition of ten S (M〇10 4v3Wl 2〇x) (CuMo〇 5W〇 5〇4)丨6. According to the present invention, it is preferred that the temperature difference between the maximum value of the heating point of the reaction gas mixture in the individual reaction zone and the specific temperature of the reaction zone generally does not exceed 80 ° C (for example, via, for example, an inert material) Dilution) advantageously selects a fixed catalyst bed for the propylene oxidation stage and a fixed catalyst bed for the acrolein oxidation stage according to the invention. This temperature difference is usually $70 ° C, often from Sichuan to several, and this temperature difference is small. For safety reasons, also in a manner known to those skilled in the art (e.g., by diluting with, for example, an inert material), to effect a peak-to-salt temperature sensitivity as defined in 卩 八 八 598 598 598 Or $7°C, or ^5. (:, or S3C mode, select these fixed catalyst beds. The reactors in the aftercooler and acrolein reaction stages are connected by a connecting tube of less than 25 meters in length. The reactor configuration described is in this document. All other reactor configurations and fixed bed catalyst feeds described may also be in high propylene or acrolein loading

The following operations, as described in the document W0 01/363 64, DE-A 19927624, DE_A

In 19948248, DE-A 19948523, DE-A 19948241, DE-A 19910506, DE-A 10302715 and EP-A 1106598. The reaction zone A', B', or A, B may have a temperature as suggested in this document, although in accordance with the teachings of the aforementioned documents, the second reaction zone in each case has a greater The manner in which the temperature of the first reaction zone is high. The heating point temperature of the second reaction zone in each case is always lower than the temperature of the first reaction zone in each case. O:\91\91169.DOC -37- - however, the acrolein minus $ according to the invention in the procedure according to the invention produces an increased choice of acrylic acid generation relative to the procedure recommended for the same propylene load Sex. In the subsequent examples and comparative examples and the following reactor configurations, the annular shaped dilute body and the annular shaped catalyst body of the propylene light reaction stage are formed into a bulk and a spherical shaped catalyst body (each having 2 to 53⁄4) The radius of the rice, and from 1 to 3% by weight, often from 20% by weight of the active composition content). Statements regarding the operation under high acrolein loading in the above documents are still valid. EXAMPLES AND COMPARATIVE EXAMPLES Reaction tube (V2A steel; outer diameter 30 mm, wall thickness 2 mm, inner diameter % mm, length: 350 cm, and centered in the middle of the reaction tube to allow for use in the reaction tube The heat pipe (outer diameter 4 mm) of the thermal element over its entire length is fed from top to bottom as follows: Section 1: Length 20 cm as the initial bed 7 mm χ 7 mm χ 4 mm (outer diameter X length) X inner diameter) The hard talc ring of the shape. Paragraph 2: Length 90 cm

3 X 里 / ° 7 乂 乂 3 mm X 4 mm (outer diameter X length X inner diameter) shape of the hard talc ring and 70% by weight of the catalyst mixture of the coated catalyst from the section 4 catalyst mixture. Section 3: Length of 50 cm 2 〇% by weight 7 mm x 3 mm X 4 mm (outer diameter X length X inner diameter) The shape of the hard talc ring and 80% by weight of the O from the segment 4: \9l\91169. DOC -38 - 1324994 Catalyst addition of a homogeneous mixture of coated catalysts. Section 4: Length of 190 cm According to DE A 1 〇〇 46928, the ring shape of the preparation example 5 (7 mm X 3 mm X 4 mm = outer diameter x length χ inner diameter) coated catalyst catalyst (stoichiometry: from 175 cm before the top to bottom is maintained at a constant temperature by a salt bath A pumped in countercurrent. The second 175 cm is maintained by a salt bath b pumped in countercurrent. Gas phase oxidation: The first The reaction stage continuously adds the initial reaction gas mixture of the following composition' and changes the load and strange temperature of the reaction tube: 5.5% by volume of acrolein, 0.3% by volume of propylene, 6.0% by volume of molecular oxygen, 0.4% by volume ( : 0, 0.8% by volume (: 02, 9.0% by volume of water, and 78.0% by volume of nitrogen. The reaction gas mixture flows from the top to the bottom through the reaction tube. The pressure at the inlet to the reaction tube is acrolein per The hourly space speed function varies between 1.6 and 2.1 bar. A small amount of sample is taken from the product gas mixture at the outlet of the reaction tube and analyzed by chromatography. At the end of reaction zone A, there is also an analysis point. Each Time-space velocity and the results obtained for the function of the salt Logarlu 0-\91\9M69.doc •39· 1324994 (the letter E in parentheses refers to the examples, and the letter C in parentheses refers to the comparative example) TA, TB is the temperature of the salt bath that is circulated by pumping in reaction zones A and B.

The acrolein conversion rate of Caa at the end of reaction zone A, in mole %.

Cab is the acrolein conversion rate at the end of reaction zone B, in mole %. SAA is the selectivity in terms of acrylic acid converted from acrolein to the product gas mixture, in mole percent.

TmaxA, TmaxB are the maximum temperatures of the reaction gas mixture in reaction zones A and B, in °C. Table acrolein hourly space velocity (1(STP)/1 · h) TA TB rpmaxA ^maxH Caa Cab SAA 106 (E) 260 260 302 276 80.7 99.3 95.4 108 (E) 262 259 312 275 84.8 99.3 95.8 104 (C ) 257 262 285 291 64.0 99.3 94.9 152 (C) 263 269 303 287 78.8 99.3 95.8 147 (C) 257 278 278 310 61.3 99.3 95.0 O:\91\9U69.DOC -40-

Claims (1)

1324994 Picking up, applying for a patent garden: 1. A method for partially oxidizing acrolein to acrylic acid in a gas phase under heterogeneous catalysis, which comprises reacting a starting reaction gas mixture in a reaction stage (including Acrolein, molecular oxygen and at least one inert gas containing at least 2% by volume of molecular nitrogen, and comprising 〇2: C3H40 molar ratio g 〇5 molecular oxygen and acrolein) are transported on a fixed catalyst bed, the fixed catalyst bed The reaction zone A is set in two spatially continuous reaction zones A and B. The temperature of the reaction zone A is in the range of 230 to 320 C and the temperature of the reaction zone b is also in the range of 230 to 320 t. The composition is at least one multi-metal oxide comprising the elements Mo and V in a manner such that the reaction zone A extends to a conversion of acrolein from 45 to 85 mol%, and when the initial reaction gas mixture is fixed by the whole During the catalyst bed, the acrolein conversion rate is g 90%, and the selectivity of acrylic acid in terms of converted acrolein is 290 mol%, and the initial reaction gas mixture flows through the reaction zone. The sequence corresponds to the alphabetical order of the reaction zone, wherein a) the hourly space velocity of acrolein in the initial reaction gas mixture contained on the fixed catalyst bed is $145 liter (STp) of acrolein/liter fixed catalyst bed. Hours and 27 liters liter (STp) fixed catalyst bed of acrolein/liter hr, b) volume of fixed catalyst bed _ specific activity is constant or increased at least once in the flow direction of the reaction gas mixture on the fixed catalyst bed, and c) from the final temperature TmaxA (which is the highest temperature of the reaction gas mixture in reaction zone a) and the highest temperature Τ-ΜΒ (the reaction gas mixture is in anti-O:\91\91169.DOC 1324994 2. Area B The highest temperature in the process is formed as in the method of claim 1 of the patent scope 2 0 C and S 75 t:. The difference is T_ and TmaxB. 'The difference TmaxA _ TmaxB is 3. The method of the fifth item of the patent scope of the 5th patent, Gans-V. Not β heart, wherein the difference TmaxA _ Ding Jia "g3 °c and S60 °c. ', 4. The method of claim 1, wherein the difference is S5 ° C and S 40 ° C. 5. The method of any one of the preceding claims, wherein the space velocity of the two alkenals per hour in the initial reaction gas mixture on the fixed catalyst bed is g70 liters (STP) Propionaldehyde / liter · hour 10,000 S140 liters (STP) C women / liters · hours. The method of any one of claims 1 to 4, wherein the package The hourly space velocity of acrolein in the initial reaction gas mixture on the fixed catalyst bed is 80 liters (STP) acrolein / liter hour and S 130 liter (STP) propylene road / liter hour. 7. The method of any one of claims 1 to 4 wherein the active catalyst bed of the fixed catalyst bed is at least one multi-metal oxide active composition of the formula: M〇i2VaX1bX2cX3dx4ex5fX6g〇n The variables are defined as follows: X1=W, Nb, Ta, Cr and/or Ce, X2=Cu, Ni, Co, Fe, Μη and/or Zn, X3=Sb and/or Bi 'X4 =—or a variety of alkali metals ' O:\9l\91169.DOC -2- 1324994 x5=—or multiple soil testing metals, X6 = Si, A1, Ti and/or Zr, a = 1 to 6, b = 0.2 to 4, c=0.5 to 18, d=0 to 40, e=0 to 2, f=0 to 4, g=0 to 40, and n=the valence and frequency of the element other than oxygen in IV The number of decisions. The method of any one of claims 1 to 4, wherein the volume-specific activity of the fixed catalyst bed is increased at least once in the flow direction of the reaction gas mixture on the fixed catalyst bed. O:\91\91I69.DOC