JP4779309B2 - Catalyst mixer and catalyst mixing method - Google Patents

Description

The present invention relates to a catalyst mixture, was engaged mixed particular mixed-method the composite oxide catalyst and the inert filler used in the gas-phase catalytic oxidation reaction using a fixed bed multitubular reactor, as well composite The present invention relates to a small package of an oxide catalyst and an inert packing.

  When producing acrolein or metaacrolein from propylene using an oxidation catalyst, it is known to dilute the catalyst with an inert packing. For example, Patent Document 1 discloses that an active catalyst is deactivated in order to improve the yield by increasing the amount of reaction gas conducted in a dangerous range or to prevent excessive oxidation and local overheating (hot spot). It is described to dilute with material (inert packing) to reduce the activity of the catalyst.

However, when the catalyst and the inert packing are mixed and diluted by such a conventional technique, although an effect can be obtained as it is, the effect depends on the mixed state of the catalyst and the inert packing, and is not always satisfactory. It wasn't going. That is, there is a problem that the effect of suppressing hot spots cannot be obtained satisfactorily because the catalyst and the inert filler are not uniformly mixed at a predetermined volume ratio. As a result, there is a need for a more effective method for sufficiently solving problems caused by hot spots. Patent Document 1 does not describe anything about a mixing method and a mixing state when diluting a catalyst with an inert material, which is useful for solving such a problem.
Japanese Patent Publication No.53-30688

  In view of the prior art as described above, it is an object of the present invention to provide a more effective means for solving problems caused by hot spots in a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor. .

  In order to solve the above problems, the present inventors have studied a mixing method of the catalyst and the inert packing, and as a result, the partition inside the hopper is divided by partition walls in accordance with the volume ratio of the catalyst and the inert packing. And found that the catalyst and the inert filler can be mixed easily in a desired volume ratio by mixing the catalyst and the inert filler in a catalyst mixer in which this hopper and an unstirred mixer are combined. It is.

The present invention is a method of mixing a plurality of types of packing using a catalyst mixer in which an unstirred mixer is disposed below a hopper, wherein the plurality of types of packing are fixed bed multitubular reactors. A composite oxide catalyst and an inert packing used in a gas phase catalytic oxidation reaction using a hopper, in order to divide and accommodate the plural types of packing, the hopper is partitioned into a plurality of partitions, The horizontal cross-sectional area ratio is substantially equal to the volume ratio of each packing, and the above-mentioned composite oxide catalyst and inert packing are charged in a predetermined amount per reaction tube of a fixed bed multitubular reactor. Alternatively, the reaction mixture is divided into a plurality of reaction zones and packed into a plurality of reaction zones, and each reaction zone is divided into a predetermined amount, mixed and packaged, and the divided composite oxide catalyst and the inert packing are divided into 8 portions. When the volume ratio of the composite oxide catalyst to the inert packing, Variation coefficient of the volume ratio of coupling oxide catalyst to provide a catalyst mixture wherein 10% or less.

  According to the method of the present invention, the composite oxide catalyst and the inert packing can be mixed at a predetermined volume ratio, so that hot spots are sufficiently suppressed in a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor. can do. Thereby, the catalyst performance can be stably maintained, and acrolein and / or acrylic acid can be stably produced in a high yield from an oxidation reaction product such as propylene.

  The present invention is characterized in that a catalyst and a catalyst other than the catalyst are mixed in a catalyst mixer. For example, a composite oxide catalyst (hereinafter referred to as a composite oxide catalyst used in a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor). In some cases, the catalyst is mixed with the inert filler by a catalyst mixer, but the present invention is not limited to the catalyst and the inert filler.

  Hereinafter, the present invention will be specifically described with reference to the drawings. However, the drawings are examples of the invention, and the present invention is not limited to the drawings and the description thereof.

The catalyst mixer used in the present invention will be described with reference to FIG.
As shown in FIG. 1, the catalyst mixer used in the invention has an unstirred mixer 4 disposed below a hopper 2. The hopper 2 has a capacity for receiving a predetermined amount to be filled per reaction tube, or a predetermined amount of catalyst and inert packing in each reaction zone to be divided and packed into a plurality of reaction zones per reaction tube. The bottom part can be opened and closed by a damper-3. Inside the hopper 2, a partition wall 1 is installed upright so that a plurality of kinds of fillers, for example, a catalyst and an inert filler can be substantially divided and accommodated. In this example, one partition wall 1 is provided to separate the catalyst and the inert packing, but the number of partition walls 1 can be increased depending on the number of types of packing. In this case, the partition wall 1 is preferably provided so that its position can be adjusted, that is, movable. For example, although not shown, the position adjustment is performed by providing recesses and grooves into which the partition walls 1 can be inserted at regular intervals on the inner wall and upper end of the hopper 2 and replacing the partition walls 1 with these recesses and grooves. It is possible to use a method or a method in which the partition wall 1 is provided so as to be movable in the lateral direction in the hopper 2 and is locked to the upper end portion of the hopper 2 with a screw or a hook at a predetermined position. However. The position adjusting means for the partition wall 1 is not limited to these methods as long as the partition wall can be held at a predetermined position in the hopper.

  The cross-sectional area ratio in the horizontal direction of each section inside the hopper 2 divided by the partition wall 1 can be adjusted by changing the position of the partition wall 1. Then, by adjusting the position of the partition wall 1, the horizontal sectional area ratio of each section, preferably at least the horizontal sectional area ratio at the outlet of the hopper 2 is made equal to the volume ratio of each of the plurality of types of fillers. be able to. Since the cross-sectional area ratio and the volume ratio are the same in this way, the catalyst and the inert filler are placed in the corresponding compartment by accommodating the catalyst and the inert filler in the corresponding compartment. 2 can be charged inside.

  The area of the partition wall 1 is not particularly limited as long as a plurality of types of fillers can be substantially divided, but is preferably 60% or more, more preferably 80% or more, most preferably, of the vertical cross section of the filler charged into the hopper. Is 95% or more. When the area of the partition wall 1 is smaller than 60%, the partitioning by the partition wall 1 is insufficient, and a plurality of kinds of fillers cannot be mixed substantially uniformly at a predetermined volume ratio. May not be sufficiently obtained.

  Next, the non-stirring mixer 4 will be described with reference to FIG. As this unstirred mixer 4, the unstirred mixer shown by JIS-Z-8840 (p14) can be used. FIG. 2 schematically shows such an unstirred mixer. For example, a static mixer in which a plurality of elements 7 are arranged inside a cylindrical housing 6 having an inlet 5 at the upper end can be used. . The inner diameter of the housing 6 is set such that the catalyst and the inert packing do not cause bridging in the housing. Usually, since the catalyst and the inert packing have a particle diameter of several mm to several tens mm, the inner diameter is preferably 70 mm or more, more preferably 100 to 300 mm. Bridging may occur frequently in a housing having an inner diameter of less than 70 mm. On the other hand, if the inner diameter is larger than 300 mm, the material required for the member increases, which is economically disadvantageous. The length of the housing 6 may vary depending on the element 7, but is preferably about 2 to 20 times the inner diameter.

  The element 7 disposed inside the housing 6 may be a shape that allows a catalyst having a particle diameter of several mm to several tens mm and an inert filler to pass therethrough, for example, a spiral element. Usually, 2 to 20 spiral elements are used while being stepped in the housing 6, but may be formed as a single element. The catalyst to be mixed and the inert packing are supplied to the inlet 5 of the non-stirring mixer 4 by opening the damper 3 of the hopper 2 and mixed while dropping in the housing 6 along the spiral element 7. The In this case, since the catalyst and the inert packing are divided in the hopper 2 partitioned by the partition wall 1 according to the mixing volume ratio, they can be supplied to the charging port 5 at a constant ratio. Such a mixing method using a spiral element is effective for mixing the catalyst and the inert packing without destroying the catalyst particles because the catalyst and the inert packing are mixed without stirring.

  In the present invention, the mixed state of the catalyst and the inert packing means that a predetermined amount of the mixed catalyst and the inert packing filled in one reaction tube (hereinafter referred to as a catalyst and an inert packing per reaction tube). Catalyst is divided into 8 equal parts within a range of variation of ± 15% by volume for convenience and the volume ratio of each divided catalyst to the inert packing is determined. It is evaluated by the coefficient of variation of the volume ratio. Here, the variation coefficient is a value represented by (s / x × 100), where x is an average value of n pieces of data and s is a standard deviation. A large variation count means that the variation in the mixing ratio of the catalyst is large.

In the present invention, the variation coefficient of the volume ratio of the catalyst is 10% or less , and more preferably 8% or less. When this variation count is larger than 10%, the effect of suppressing hot spots in the gas phase catalytic oxidation reaction becomes insufficient due to the heterogeneity of the catalyst, and when acrolein and / or acrylic acid is produced from an oxidation reaction product such as propylene. This is not preferable because the yield of is reduced.

  In addition, as a method of equally dividing the contents of the subdivided package, for example, a divider shown in FIGS. 3 and 4 can be used. 3 is a type in which the receivers 8 are arranged in a circle, and FIG. 4 is a type in which the receivers 8 are arranged in series. A measuring container 9 having an internal volume of 8 equal parts is installed in the receiver 8, and the contents of the small package are put into the measuring container 9. When the measuring container 9 is filled, the rotating shaft 10 or the pulley 11 is moved, and subsequently put into the measuring container 9 installed in the next receiver 8. By repeating this, the contents of the small package can be equally divided into eight receivers 8 or weighing containers 9.

  In addition, the volume of the packing in the present invention can be measured using a volume measuring device such as a graduated cylinder. Moreover, it can also measure using weight measuring instruments, such as an electronic balance, in terms of a bulk density, and a commercially available automatic weight measuring instrument can also be used.

  The inert filler used in the present invention may be a material that does not cause an excessive side reaction in the reaction, for example, oxide, steatite, mullite, high-temperature treated oxide such as alumina, zirconia, titania, magnesia, silica, etc. A high-temperature sintered material such as silicon carbide or silicon nitride can be used.

A typical catalyst used in the present invention is a composite oxide catalyst used in a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor. Specific examples include a catalyst used in a gas phase catalytic oxidation reaction for producing acrolein or metaacrolein from propylene. A preferred embodiment of the composite oxide catalyst is exemplified by a catalyst represented by the following general formula (1).
MoaBibCocNidFeeXfYgZhQiSijOk (1)
(However, X represents at least one of Na, K, Rb, Cs and Tl, Y represents at least one of B, P, As and W, and Z represents Mg, Ca, Zn, Ce and Sm. Q represents halogen, and a to k and m represent atomic ratios of the respective elements, and when a = 12, b = 0.5 to 7, c = 0 to 10, d = 0 to 10, c + d = 1 to 10, e = 0.05 to 3, f = 0.005 to 3, g = 0 to 3, h = 0 to 1, i = 0 to 0.5, j is in the range of 0 to 48, and k is a value that satisfies the oxidation state of other elements.)

  In the above, molybdenum (Mo), bismuth (Bi), silicon (Si), cobalt (Co), nickel (Ni), iron (Fe), magnesium (Mg), calcium (Ca), zinc (Zn), Cerium (Ce), samarium (Sm), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), thallium (Tl), boron (B), phosphorus (P), arsenic (As), Each element of tungsten (W), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) was expressed using element symbols in parentheses. The molybdenum-bismuth complex oxide catalyst represented by the general formula (1) is known per se and can be prepared by a known method.

Another typical catalyst used in the present invention is represented by the following general formula (2) mainly composed of molybdenum, which is used in a reaction for producing a corresponding unsaturated carboxylic acid by subjecting an unsaturated aldehyde to a gas phase catalytic oxidation reaction. It is a complex oxide catalyst having
MoaVbCucXdYeZfOg (2)
(Wherein X is at least one element selected from the group consisting of W and Nb, Y is at least one element selected from the group consisting of Fe, Co, Ni, and Bi; Represents at least one element selected from the group consisting of Ti, Zr, Ce, Cr, Mn and Sb, wherein a, b, c, d, e, f and g represent the atomic ratio of each element; = 12, b = 1 to 12, c = 0 to 6, d = 0 to 12, e = 0 to 100, f = 0 to 100, g is necessary to satisfy the valence of each component. (The number of oxygen atoms.)

  The method for preparing the catalyst used in the present invention is not particularly limited except for the firing conditions. Usually, after the required amount of the source compound containing each element component is appropriately dissolved or dispersed in an aqueous medium and heated and stirred. The powder obtained by evaporating, drying, drying and pulverizing is molded by a method such as extrusion molding, granulation molding, tableting molding or the like to obtain a molded body. There is no restriction | limiting in particular also about the shape of a catalyst, a magnitude | size, etc., It can select suitably from a well-known shape, magnitude | size, etc. For example, the shape may be any of a spherical shape, a cylindrical shape, a ring shape, and the like. At this time, inorganic fibers such as glass fibers that are generally known to have an effect of improving the strength and degree of pulverization of the catalyst, and various whiskers may be added. In order to control the physical properties of the catalyst with good reproducibility, additives generally known as powder binders such as ammonium nitrate, cellulose, starch, polyvinyl alcohol and stearic acid can also be used.

  In the present invention, the composite oxide represented by the general formula (I) can be used alone, but alumina, silica, silica-alumina, silicon carbide, titanium oxide, magnesium oxide, aluminum sponge, silica -It may be supported on a carrier generally known as an inert carrier such as titania. At this time, the inorganic fiber or the like may be added to improve the strength of the catalyst, or the additive such as ammonium nitrate may be used to control the physical properties of the catalyst with good reproducibility.

  The composite oxide catalyst is prepared by calcining the catalyst as the molded body or the support body at a temperature of 300 to 650 ° C. for about 1 to 20 hours under an atmosphere gas flow.

  The gas-phase catalytic oxidation reaction using the Mo-Bi-Fe-based composite oxide catalyst is specifically a gas-phase catalytic oxidation of propylene by a method generally used in producing acrolein and acrylic acid. It can be carried out. For example, a mixed gas composed of 1 to 15% by volume of propylene, 3 to 30% by volume of molecular oxygen, 0 to 60% by volume of water vapor, 20 to 80% by volume of inert gas such as nitrogen and carbon dioxide, etc. What is necessary is just to introduce | transduce into a catalyst layer under the space velocity (SV) 300-5000hr <-1> under the pressurization of 250-450 degreeC and 0.01-1 MPa.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

In the following description, the definitions of conversion and yield are as follows.
Conversion (mol%) = (number of moles of reacted propylene / number of moles of supplied propylene)
× 100
Yield (mol%) = (moles of acrolein and acrylic acid produced / pro fed
Number of moles of pyrene) x 100

Example 1
Mo: Bi: Ni: Co: Fe: Na: B: K: Si = 12: 5: 2: 3: 0.5: As a catalyst for producing acrolein or acrylic acid from propylene by a gas phase catalytic oxidation reaction A composite oxide catalyst powder having an atomic ratio of 0.1: 0.2: 0.1: 24 was prepared. After adding 2 parts by weight of graphite (molding aid) to 100 parts by weight of this powder and molding it into a ring shape having an outer diameter of 5 mm, an inner diameter of 2 mm, and a height of 4 mm, it is fired at 500 ° C. for 6 hours under air flow. Catalyst.

Next, the catalyst and the inert packing (alumina balls having a diameter of about 5 mm) were mixed using the catalyst mixer shown in FIG. First, 500 ml of the catalyst and 500 ml of the inert packing were mixed and packed in small bags. An unstirred mixer 4 was placed below the hopper 2, and a polyethylene bag (thickness 0.08 mm × width 180 mm × length 270 mm) was set at the lower outlet of the unstirred mixer 4. The position of the partition wall 1 was adjusted so that the internal volume of the hopper 2 was 1: 1. 500 ml of the catalyst was charged into one section divided into two by the partition wall 1, and 500 ml of inert filler was charged into the other section. Next, the damper 3 was opened, and the catalyst and the inert filler were put into an unstirred mixer. The mixture of the catalyst and the inert filler discharged from the lower outlet of the non-stirring mixer 4 was received by a polyethylene bag, degassed, and then heat-sealed to obtain a small package. The same operation was repeated 6 times to prepare six subpackages, which were designated as subpackages A-1 to A-6, respectively.
Table 1 shows the results of evaluating the mixed state of the catalyst and the inert packing in the subpackages A-1 to A-5.

  Subsequently, the mixture of the catalyst and the inert packing subdivided into the above-mentioned subdivided package A-6 is filled in the raw material gas inlet side of a stainless steel reaction tube having a diameter of 27 mm provided with a thermocouple, and the above-mentioned raw material gas outlet side is filled with the above-mentioned mixture. 1000 ml of catalyst was charged.

  Next, in order to confirm the catalyst performance, propylene 8.5%, air 68%, water vapor 15%, nitrogen 8 under conditions of a gas space velocity of 1000 hr-1 (0 ° C. reference), an inlet gauge pressure of 100 kPa, and a reaction temperature of 310 ° C. Propylene was oxidized by passing a 5% mixed gas. As for the reaction results, the propylene conversion rate was 98.8%, and the total yield of acrylic acid and acrolein was 92.6%. The maximum temperature of the reaction catalyst layer was 383 ° C.

(Comparative Example 1)
The partition wall 1 of the catalyst mixer shown in FIG. 1 was removed, and the same catalyst and inert packing as in Example 1 were used, and small bags were packed by the following method.
First, 500 ml of the catalyst and 500 ml of the inert packing were mixed and packed in small portions. An unstirred mixer 4 was placed below the hopper 2, and a polyethylene bag (thickness 0.08 mm × width 180 mm × length 270 mm) was set at the lower outlet of the unstirred mixer 4. Next, 500 ml of the catalyst was put into the hopper 2, and then 500 ml of the inert filler was put into the hopper. Next, the damper 3 was opened, and the catalyst and the inert filler were put into the non-stirring mixer 4. The mixture of the catalyst and the inert filler discharged from the lower outlet of the non-stirring mixer 4 was received by a polyethylene bag, degassed, and then heat-sealed to obtain a small package. The same operation was repeated 6 times to prepare six subpackages, which were designated as subpackages B-1 to B-6, respectively.
Table 2 shows the results of evaluating the mixed state of the catalyst and the inert packing in the subpackages B-1 to B-5.

  On the other hand, a mixture of the forming catalyst and the inert packing of the above-mentioned subdivided package B-6 is filled on the raw material gas inlet side of a stainless steel reaction tube having a diameter of 27 mm provided with a thermocouple, and 1000 ml of the catalyst is placed on the raw material gas outlet side. Filled.

  Next, in order to confirm the catalyst performance, propylene 8.5%, air 68%, water vapor 15%, nitrogen 8 under conditions of a gas space velocity of 1000 hr-1 (0 ° C. reference), an inlet gauge pressure of 100 kPa, and a reaction temperature of 310 ° C. Propylene was oxidized by passing a 5% mixed gas. As for the reaction results, the propylene conversion rate was 98.6%, and the total yield of acrylic acid and acrolein was 91.1%. The maximum temperature of the reaction catalyst layer was 410 ° C.

  In the present invention, a catalyst and an inert packing are mixed at a predetermined volume ratio, and an effect of suppressing hot spots in a gas phase catalytic oxidation reaction using a fixed bed multitubular reactor is obtained. It can be applied to the mixing of the catalyst and the inert packing when producing metaacrolein, and a high yield can be achieved.

The front view of the catalyst mixer used by this invention. The schematic of the non-stirring mixer of FIG. Explanatory drawing of a circular array type divider. Explanatory drawing of the dividing device of a serial arrangement type.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bulkhead 2 Hopper 3 Damper 4 Unstirred mixer 5 Input port 6 Housing 7 Element 8 Receiver 9 Measuring container 10 Rotating shaft 11 Pulley

Claims (2)

A method of mixing a plurality of types of packing using a catalyst mixer in which an unstirred mixer is disposed below a hopper, wherein the plurality of types of packing are gasses using a fixed-bed multitubular reactor. A composite oxide catalyst used for a phase catalytic oxidation reaction and an inert packing, and the hopper is partitioned into a plurality of partitions in order to divide and accommodate the plurality of types of packing, and the horizontal direction of each partition The cross-sectional area ratio is made substantially equal to the volume ratio of each packing, and the above-mentioned composite oxide catalyst and the inert packing are charged in a predetermined amount per reaction tube of a fixed bed multitubular reactor or reaction Combined into a predetermined amount of each reaction zone to be divided into a plurality of reaction zones and packed in one tube, mixed and packaged, and the composite oxide catalyst and the inert packing when divided into 8 parts are combined. Composite oxide in the volume ratio of product catalyst to inert packing Catalyst mixture wherein the variation coefficient of the volume ratio of the medium is 10% or less. A small package packaged in small bags by the catalyst mixing method of claim 1 .

Images