JP4809692B2 - Method for producing catalyst for synthesis of unsaturated aldehyde and unsaturated carboxylic acid - Google Patents

Description

  The present invention responds to each of the above by vapor-phase catalytic oxidation of propylene, isobutylene, tertiary butyl alcohol (hereinafter referred to as TBA) or methyl tertiary butyl ether (hereinafter referred to as MTBE) using molecular oxygen. The present invention relates to a method for producing a catalyst used in the synthesis of an unsaturated aldehyde and an unsaturated carboxylic acid.

Catalysts conventionally used for producing acrolein and acrylic acid by vapor-phase catalytic oxidation of propylene, and catalysts used for producing methacrolein and methacrylic acid by vapor-phase catalytic oxidation of isobutylene, TBA or MTBE Many proposals have been made. For example, Patent Document 1 describes a method in which a slurry containing a catalyst component is atomized and then heat-treated. Patent Document 2 describes a catalyst production method in which bismuth trioxide and a molybdenum-containing aqueous solution are mixed, subjected to ultrasonic treatment, and mixed with an iron-containing aqueous solution. Furthermore, Patent Document 3 describes a method of atomizing a slurry containing a catalyst component while performing a heat treatment.
JP-A-7-289902 Japanese Patent Laid-Open No. 8-24652 JP 10-258233 A

  However, the catalysts known so far are still not sufficient in terms of yield, and development of a catalyst production method capable of obtaining unsaturated aldehydes and unsaturated carboxylic acids in high yields is desired. ing.

  The present invention relates to a method for producing a catalyst capable of producing a corresponding unsaturated aldehyde and unsaturated carboxylic acid in high yield by subjecting propylene, isobutylene, TBA or MTBE to vapor phase catalytic oxidation using molecular oxygen. The purpose is to provide.

In the present invention, propylene, isobutylene, tertiary butyl alcohol or methyl tertiary butyl ether is subjected to gas phase catalytic oxidation using molecular oxygen to synthesize the corresponding unsaturated aldehyde and unsaturated carboxylic acid. A process for producing an unsaturated aldehyde and unsaturated carboxylic acid synthesis catalyst containing at least molybdenum, bismuth and iron as catalyst components, comprising:
A step of preparing a raw material slurry in which at least a raw material that does not dissolve in water among the raw materials of the catalyst component is dispersed in water;
A step of preparing a raw material solution in which other raw materials are dissolved in water;
Mixing the raw material slurry with the raw material solution while atomizing the raw material slurry to prepare a catalyst precursor slurry containing a catalyst precursor having an average median diameter of 0.5 to 10 μm;
It is a manufacturing method of the catalyst for unsaturated aldehyde and unsaturated carboxylic acid synthesis characterized by having.

  The present invention also lies in a method for producing an unsaturated aldehyde and unsaturated carboxylic acid synthesis catalyst, characterized in that the step of preparing the raw slurry in the above invention is performed while atomizing.

  According to the present invention, a catalyst capable of producing a corresponding unsaturated aldehyde and unsaturated carboxylic acid in high yield by vapor-phase catalytic oxidation of propylene, isobutylene, TBA or MTBE using molecular oxygen. A manufacturing method can be provided.

  The catalyst produced in the present invention is used when vapor-phase catalytic oxidation of propylene, isobutylene, TBA or MTBE using molecular oxygen to synthesize the corresponding unsaturated aldehyde and unsaturated carboxylic acid. The component constituting the catalyst (catalyst component) contains at least molybdenum, bismuth and iron. When propylene is used as a raw material, acrolein and acrylic acid are produced, and when other raw materials are used, methacrolein and methacrylic acid are produced.

  The production method of the present invention is particularly suitable for producing a catalyst containing a composite oxide having a composition represented by the general formula (1).

Mo _a Bi _b Fe _c M _d X _e Y _f Z _g Si _h O _i (1)
In the formula, Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, respectively, M represents at least one element selected from the group consisting of cobalt and nickel, X represents chromium, At least one element selected from the group consisting of lead, manganese, calcium, magnesium, niobium, silver, barium, tin, tantalum and zinc; Y is phosphorus, boron, sulfur, selenium, tellurium, cerium, tungsten, Z represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and thallium, and represents at least one element selected from the group consisting of antimony and titanium. a, b, c, d, e, f, g, h, and i represent atomic ratios of the respective elements. When a = 12, b = 0.01-3, c = 0.01-5, d = 1 -12, e = 0 to 8, f = 0 to 5, g = 0.001 to 2, h = 0 to 20, and i is an oxygen atomic ratio necessary to satisfy the valence of each component. is there. The composition of the composite oxide other than oxygen can be estimated by dissolving the catalyst in aqueous ammonia and analyzing it by ICP emission analysis and atomic absorption analysis.

  Hereinafter, a method for producing the unsaturated aldehyde and unsaturated carboxylic acid synthesis catalyst will be described.

  First, a raw material slurry in which at least a raw material that does not dissolve in water among the raw materials of the catalyst component is dispersed in water is prepared. Also, a raw material solution in which other raw materials are dissolved in water is prepared. That is, the raw materials for the catalyst component are classified into raw materials that do not dissolve in water and raw materials that dissolve in water, and at least raw materials that do not dissolve in water are dispersed in water to form raw slurry. A part of the raw material dissolved in water may be mixed with the raw material slurry. And a part or all of the raw material melt | dissolved in the water which is the remaining raw material which was not mixed with raw material slurry is dissolved in water, and it is set as a raw material solution.

  As a method of preparing the raw slurry, it is not necessary to limit to a special method, and various methods such as a precipitation method and an oxide mixing method that are well known from the past are used unless significant uneven distribution of components is involved. Can do. When preparing the raw material slurry, it is preferable to carry out the atomization treatment described later. By doing so, the performance of the obtained catalyst becomes higher.

  As raw materials for the catalyst component, oxides, sulfates, nitrates, carbonates, hydroxides, ammonium salts, halides, and the like of each element can be used. Examples of the molybdenum raw material include ammonium paramolybdate and molybdenum trioxide. Examples of the bismuth raw material that can be used include bismuth trioxide, bismuth nitrate, bismuth carbonate, and bismuth hydroxide. As the iron raw material, for example, ferric nitrate, ferric chloride and the like can be used. The raw material of the catalyst component may be one type for each element, or two or more types may be used in combination. Further, a raw material insoluble in water such as bismuth nitrate may be used by dissolving in an acid such as nitric acid in advance.

  As the raw material for the catalyst component, at least one raw material that does not dissolve in water and at least one raw material that dissolves in water will be selected. For each element of the catalyst component, a raw material that does not dissolve in water is selected. Or you may select the raw material which melt | dissolves in water. As the molybdenum raw material, it is preferable to select one that dissolves in water. As the iron raw material, it is preferable to select one that dissolves in water.

  Next, the raw material slurry is mixed with the raw material solution while being atomized to prepare a catalyst precursor slurry. By doing so, the particle size of the catalyst precursor to be produced becomes fine and uniform, and a high-performance catalyst can be obtained with good reproducibility.

  In the present invention, as a method for atomizing the raw material slurry, it is practical to use means having excellent atomization efficiency such as a homogenizer, a bead mill, a jet mill, or ultrasonic irradiation. As an apparatus used for atomization, a rotary stirring device such as a rotary blade stirrer, a homogenizer, a pendulum type linear motion stirrer, a shaker that shakes the whole container, a vibrating stirrer that uses ultrasonic waves, etc. A commonly used stirring device can be used. Among them, it is preferable to use a rotary stirring device such as a rotary blade stirrer or a homogenizer because the strength of stirring can be easily adjusted and industrially simple. In particular, the use of a homogenizer is preferable in that a highly active catalyst can be obtained.

  The temperature at the time of mixing the raw material slurry and the raw material solution is set lower than the temperature at the time of heat treatment described later. Usually, it is higher than 40 ° C, preferably 50 ° C or higher. Further, it is usually lower than 80 ° C and preferably 70 ° C or lower.

  At this time, the atomization process is performed until the average median diameter of the catalyst precursor contained in the catalyst precursor slurry becomes 0.5 to 10 μm. The average median diameter of the catalyst precursor is preferably 0.8 μm or more, and particularly preferably 1.0 μm or more. If the average median diameter is too small, it becomes difficult to control the catalyst activity. The average median diameter of the catalyst precursor is preferably 8 μm or less, and particularly preferably 6 μm or less. When the average median diameter is reduced, the catalyst components in the obtained catalyst are homogenized, and a stable catalytic activity can be obtained. The average median diameter of the catalyst precursor can be measured using, for example, a flow distribution measuring device SALD-7000 (trade name) manufactured by Shimadzu Corporation.

  It is estimated that the high performance of the catalyst produced by the method of the present invention is not only because the particle size of the catalyst precursor is controlled, but also because the surface activity changes during the formation process of the catalyst precursor. . As one of the methods, it is effective to perform the atomization process when mixing the raw material slurry and the raw material solution, and to control the particle size of the catalyst precursor contained in the catalyst precursor slurry as described above. it is conceivable that. Therefore, even if the atomization treatment is performed after mixing the raw material slurry and the raw material solution, and the particle size of the catalyst precursor contained in the catalyst precursor slurry is controlled as described above, the effect of the present invention cannot be obtained. .

  And the said catalyst precursor slurry is heat-processed as needed. The heat treatment refers to a treatment performed by heating, and can be performed by appropriately combining aging, drying, firing, and the like.

  The aging temperature is preferably 80 to 105 ° C. The aging time is preferably 30 minutes or more, more preferably 60 minutes or more. Although the aging time may be long, it is usually performed in 300 minutes or less. “Aging” is to eliminate the dispersion of the catalyst precursor contained in the catalyst precursor slurry and homogenize it by applying heat to the catalyst precursor slurry.

  The catalyst precursor slurry that has been aged is preferably dried to form particles. The method of drying the catalyst precursor slurry to form particles is not particularly limited. For example, a method of drying using a spray dryer, a method of drying using a slurry dryer, a method of drying using a drum dryer, or evaporation. A method of pulverizing a lump of dried product by drying can be applied. Among them, it is preferable to obtain dry spherical particles using a spray dryer from the viewpoint that particles are obtained simultaneously with drying and the shape of the obtained particles is a spherical shape suitable for the present invention. Although the drying conditions vary depending on the drying method, when a spray dryer is used, the inlet temperature is usually 100 to 500 ° C, and the outlet temperature is usually 100 ° C or higher, preferably 105 to 200 ° C.

  The obtained dry particles may contain a salt such as nitric acid derived from the catalyst raw material, etc., and when the particles are molded into a catalyst molded body and calcined at a decomposition temperature or higher of these salts, the catalyst molded body There is a risk that the strength of the steel will decrease. For this reason, it is preferable to calcinate at this point to obtain baked particles. The firing conditions are not particularly limited, and known firing conditions can be applied. Usually, baking is performed at a temperature range of 200-600 degreeC. The calcination time is appropriately selected depending on the target catalyst and is, for example, 1 to 5 hours.

  The obtained calcined particles are then molded into a catalyst molded body. There are no particular limitations on the molding method and shape, and any shape such as a spherical shape, a ring shape, a cylindrical shape, or a star shape can be used using a general powder molding machine such as a tableting molding machine, an extrusion molding machine, or a rolling granulator. Mold to the shape of In addition, the calcined particles can be a supported catalyst supported on a carrier, and in this case, the carrier may be molded in the presence of the carrier.

  When manufacturing a catalyst molded body, you may add well-known additives, for example, organic compounds, such as polyvinyl alcohol and carboxymethylcellulose. Further, inorganic compounds such as graphite and diatomaceous earth, and inorganic fibers such as glass fibers, ceramic fibers and carbon fibers may be added. Moreover, as a component of the support | carrier used when performing loading, a silica, an alumina, a silica-alumina, a magnesia, titania etc. are mentioned.

  The catalyst obtained as described above may be calcined again. Firing is usually performed in a temperature range of 200 to 600 ° C. for 1 to 3 hours.

  An unsaturated aldehyde and an unsaturated carboxylic acid corresponding to the raw material are obtained by performing a gas phase catalytic oxidation reaction with molecular oxygen using propylene, isobutylene, TBA or MTBE as a raw material in the presence of the catalyst produced by the method of the present invention. Can be produced in a high yield. The molar ratio of raw material propylene, isobutylene, TBA or MTBE to molecular oxygen is preferably in the range of 1: 0.5-3. It is economical to use a raw material gas containing a raw material and molecular oxygen diluted with an inert gas. The concentration of the raw material in the raw material gas is preferably 2 to 40% by volume. Although it is economical to use air as the molecular oxygen source, air enriched with pure oxygen can also be used if necessary. Water vapor may be added to the source gas. The reaction pressure is preferably from normal pressure to several atmospheres. The reaction temperature can be selected in the range of 200 to 450 ° C, but the range of 250 to 400 ° C is particularly preferable. The catalyst in the reactor may be diluted with an inert substance such as silica, alumina, silica-alumina, silicon carbide, ceramic balls or stainless steel.

  Hereinafter, a catalyst production example by the method of the present invention and a reaction example using the catalyst will be specifically described. In the description, “parts” means parts by mass. Source gas and product analysis is by gas chromatography. For atomization, a rotary homogenizer is manufactured by T.K. K. A homomixer MARKII (trade name) (hereinafter referred to as a homomixer atomizer) was used under the condition of a rotational speed of 12000 rpm. The average median diameter of the particles contained in the catalyst precursor slurry was measured using a flow distribution measuring device SALD-7000 (trade name) manufactured by Shimadzu Corporation. The elemental composition of the catalyst (excluding oxygen) was estimated by ICP emission analysis and atomic absorption analysis of the catalyst dissolved in aqueous ammonia.

Moreover, the reaction rate of the raw material (isobutylene) in an Example and a comparative example, the selectivity of the unsaturated aldehyde (methacrolein) and unsaturated carboxylic acid (methacrylic acid) to produce | generate, the unsaturated aldehyde and unsaturated carboxylic acid to produce | generate The total yield (hereinafter simply referred to as total yield) was calculated according to the following formula.
Raw material reaction rate (%) = A / B × 100
Selectivity of unsaturated aldehyde (%) = C / A × 100
Selectivity of unsaturated carboxylic acid (%) = D / A × 100
Total yield (%) = (C + D) / B × 100
Here, A is the number of moles of the reacted raw material, B is the number of moles of the supplied raw material, C is the number of moles of the generated unsaturated aldehyde, and D is the number of moles of the generated unsaturated carboxylic acid.

[Example 1]
To 1000 parts of pure water at 60 ° C., 500 parts of ammonium paramolybdate, 12.4 parts of ammonium paratungstate, 23.0 parts of cesium nitrate, 27.4 parts of antimony trioxide and 33.0 parts of bismuth trioxide are added. Stir to obtain A-1 liquid (raw material slurry). Separately from this, 1000 parts of pure water at room temperature, 209.8 parts of ferric nitrate, 75.5 parts of nickel nitrate, 453.3 parts of cobalt nitrate, 31.3 parts of lead nitrate, and 85 mass% phosphoric acid aqueous solution 5 .6 parts were sequentially added and dissolved to obtain a liquid B (raw material solution).

  The liquid B was mixed while the liquid A-1 was atomized at a rotational speed of 12000 rpm with a homomixer atomizer, thereby obtaining a catalyst precursor slurry. At this time, the particles contained in the catalyst precursor slurry were atomized until the average median diameter became 1.7 μm. Thereafter, the catalyst precursor slurry was aged for 1.5 hours while being heated to 95 ° C. and stirred, and then spray-dried by a spray dryer equipped with a rotating disk type centrifugal atomizer. At this time, the rotation speed of the atomizer of the spray dryer was 11000 rpm, the inlet temperature was 165 ° C., and the outlet temperature was 125 ° C.

The dried spherical particles thus obtained were calcined for 1 hour at 300 ° C. in an air atmosphere using a rotary kiln to obtain catalyst calcined powder, and the catalyst calcined powder was pressure-molded. Thereafter, it was again calcined at 500 ° C. for 6 hours in an air atmosphere to obtain a catalyst. The composition of elements other than oxygen in the obtained catalyst was Mo ₁₂ W _0.2 Bi _0.6 Fe _2.2 Sb _0.8 Ni _1.1 Co _6.6 Pb _0.4 P _0.2 Cs _0.5 .

  10 g of this catalyst is packed in a stainless steel reaction tube with an inner diameter of 15 mm, and a raw material gas of 5% isobutylene (raw material), 12% molecular oxygen, 10% water vapor and 73% nitrogen (volume%) is supplied and contacted at normal pressure The reaction was carried out under conditions of a time of 3.6 seconds and a reaction temperature of 340 ° C., and isobutylene was vapor-phase contact oxidized with molecular oxygen. As a result, the reaction rate of isobutylene was 98.5%, the selectivity of methacrolein was 91.5%, the selectivity of methacrylic acid was 2.8%, and the total yield was 92.9%.

[Example 2]
A-2 liquid (raw material slurry) was obtained in the same manner as in the preparation of the A-1 liquid in Example 1, except that the atomization was performed with a homomixer atomizer at a rotational speed of 12000 rpm.

  The catalyst B was mixed in the same manner as in Example 1 except that the liquid B was mixed while the liquid A-2 was subsequently atomized by a homomixer atomizer and the average median diameter was 1.5 μm. The gas phase catalytic oxidation was performed in the same manner as in Example 1. As a result, the reaction rate of isobutylene was 98.5%, the selectivity of methacrolein was 91.9%, the selectivity of methacrylic acid was 2.5%, and the total yield was 93.0%.

[Comparative Example 1]
Atomization treatment is not performed during mixing of the A-1 liquid and the B liquid, and the catalyst precursor slurry after mixing is atomized by a homomixer atomizer until the average median diameter becomes 3.5 μm at a rotation speed of 12000 rpm. A catalyst was produced in the same manner as in Example 1 except that gas phase catalytic oxidation was performed in the same manner as in Example 1. As a result, the reaction rate of isobutylene was 98.1%, the selectivity of methacrolein was 90.5%, the selectivity of methacrylic acid was 2.5%, and the total yield was 91.2%.

  As mentioned above, according to the manufacturing method of this invention, the manufacturing method of the catalyst which can manufacture unsaturated aldehyde and unsaturated carboxylic acid with a high yield can be provided.

Claims (2)

Used in the synthesis of unsaturated aldehydes and carboxylic acids corresponding to propylene, isobutylene, tertiary butyl alcohol or methyl tertiary butyl ether by vapor phase catalytic oxidation with molecular oxygen. A method for producing an unsaturated aldehyde and unsaturated carboxylic acid synthesis catalyst containing at least molybdenum, bismuth and iron as catalyst components,
A step of preparing a raw material slurry in which at least a raw material that does not dissolve in water among the raw materials of the catalyst component is dispersed in water;
A step of preparing a raw material solution in which other raw materials are dissolved in water;
Mixing the raw material slurry with the raw material solution while atomizing the raw material slurry to prepare a catalyst precursor slurry containing a catalyst precursor having an average median diameter of 0.5 to 10 μm;
A process for producing an unsaturated aldehyde and unsaturated carboxylic acid synthesis catalyst characterized by comprising:   The method for producing an unsaturated aldehyde and unsaturated carboxylic acid synthesis catalyst according to claim 1, wherein the step of preparing the raw slurry is performed while atomizing.