JP2847150B2 - Method for producing acrolein or methacrolein - Google Patents

Description

The present invention relates to a process for producing acrolein or methacrolein by subjecting propylene, secondary propanol, isobutylene or tertiary butanol to gas-phase catalytic oxidation using molecular oxygen. .

[Conventional technology]

Numerous proposals have been made on catalysts used for producing acrolein or methacrolein by gas phase catalytic oxidation of propylene, secondary propanol, isobutylene or tertiary butanol with molecular oxygen.

However, catalyst performance such as catalyst activity, selectivity, catalyst stability, and catalyst life varies from lot to lot of catalyst preparation, and cannot be said to be a catalyst preparation method with good reproducibility, and improvement in that point has been desired.

[Problems to be solved by the invention]

The object of the present invention is to provide catalytic activity, methacrolein selectivity,
An object of the present invention is to provide a method for preparing a catalyst having excellent catalyst stability and good reproducibility.

[Means for solving the problem]

The present inventors require a catalyst used in the production of acrolein or methacrolein by gas phase catalytic oxidation of propylene, secondary propanol, isobutylene or tertiary butanol with molecular oxygen, particularly Mo, Bi and Fe. Acrolein or methacrolein for a catalyst containing, as an essential component, one or more elements selected from Ni and Co, and one or more elements selected from K, Rb, Cs and Tl. In order to develop a catalyst with excellent yield, selectivity and stability of rhein, the catalyst components, composition, and preparation method were studied diligently.

As a result, at the time of catalyst preparation, these catalyst components are divided into two or more types, and after being made into a solution, each solution is mixed in a short time, and a dried powder obtained by spray drying immediately without aging is used as a raw material. By preparing the catalyst, it was found that the catalyst performance such as the yield and selectivity of acrolein or methacrolein was improved, the reproducibility was improved, and the stability of the catalyst activity was greatly improved. Was completed.

That is, the method of the present invention uses the general formula Moa Bib Fec Xd Ye Zf Og (where X is one or more elements selected from Ni and Co, and Y is K, Rb, Cs and Tl). At least one element selected from the group consisting of W, Be, Mg, S, Ca, Sr, Ba, Te, Se, Ce,
It represents one or more elements selected from Ge, Mn, Zn, Cr, Ag, Sb, Pb, As, B, P, Nb, Cu, Cd, Sn, Al, Zr, Ti and Si. a, b,
c, d, e, f, and g represent the atomic ratio of each element. Based on a, when a = 12, b = 0.1-10, c = 0.1-20, d
= 2 to 20, e = 0.01 to 2, f = 0 to 4, and g is the number of oxygen atoms necessary to satisfy the valence of each component. In the presence of a catalyst containing the composition represented by the formula (1), when producing acrolein or methacrolein by gas phase catalytic oxidation using molecular oxygen, the catalyst component was divided into two or more types to form a solution. Thereafter, a method for producing acrolein or methacrolein is characterized by using a catalyst starting from a dry powder obtained by mixing the respective solutions in a short time and immediately spray-drying without aging.

The Mo-Bi-Fe-based composite oxide catalyst used in the method of the present invention is diversified in this field as an allylic oxidation catalyst, but the conventional method is disclosed in, for example, JP-A-59-46132. Usually, two or more kinds of aqueous solutions containing a catalyst component are dropped and mixed, concentrated to dryness under heating and stirring, and then calcined.

In the conventional method of drop-mixing and concentrating to dryness under heating and stirring, complicated in-liquid or solid-liquid phase reactions such as dehydration polymerization, nucleation, adsorption, precipitation, and re-dissolution occur concurrently. I think that the. These are determined by the concentration of the solution to be mixed, the temperature, the pH, the mixing order, the dropping speed, the stirring speed, the size and shape of the precipitation tank, the temperature history during heating and stirring, the stirring intensity, the concentration speed, the bath temperature during concentration, etc. Because the rate of each elementary reaction changes, slight differences in the preparation conditions result in significant changes in the chemical and physical properties of the inorganic condensation polymer, which in turn is thought to result in variations in catalyst performance. .

On the other hand, the method of the present invention is characterized in that it is mixed in a short time as possible, spray-dried immediately, and then calcined.

The basic idea of the method of the present invention is to complete the reaction in a short time in order to eliminate the slow concurrent reaction involving the liquid phase and to make the reaction as simple as possible.
That is, by mixing two or more types of solutions containing a catalyst component in the shortest possible time and immediately spray-drying, dehydration polymerization, adsorption,
The history is substantially eliminated by excluding a slow concurrent reaction involving the liquid phase such as re-dissolution, and by performing nucleation, dehydration, and drying all at once by spray drying that can be performed under constant conditions.

The solution containing the catalyst component used in the method of the present invention can be prepared, for example, by the following method.

A suitable molybdate such as ammonium molybdate is dissolved in pure water by heating, and at least one salt selected from K, Rb, Cs and Tl, such as nitrate, is added to obtain a first raw material solution. Also, a silica sol may be added to this solution. A second raw material solution is obtained by dissolving a compound of at least one element selected from Fe, Co and Ni, for example, nitrate, in pure water. A third raw material solution is obtained by dissolving a bismuth compound, for example, a nitrate, in pure water.

The raw material solution used in the method of the present invention is composed of a combination of raw material compounds such that each raw material solution does not undergo a reaction such as dehydration polymerization, nucleation, adsorption, precipitation, and re-dissolution during solution preparation or solution storage. . Therefore, the number of solutions is usually two or more, and the number is not particularly limited.

The catalyst of the present invention may contain Be, Mg, S, C
a, Sr, Ba, Te, Se, Ce, Ge, Mn, Zn, Cr, Ag, Sb, Pb, As, B, P, Nb, C
Compounds of one or more elements selected from u, W, Cd, Sn, Al, Zr and Ti can be added.

These compounds of the Z component may be added to any solution so as to be a homogeneous solution, or may be prepared as independent solutions.

The raw material of the catalyst of the present invention is preferably a compound that is decomposed into an oxide in the course of preparing the catalyst. Such compounds include, for example, nitrates, ammonium salts, organic acid salts, hydroxides, oxides, metal acids, ammonium metal salts and the like.

Further, as a raw material of silica, silica sol, silica gel, silicate ester, silicate and the like are used.

Further, when nitric acid is added to these solutions and the pH of the mixed solution when the raw material solutions are mixed is adjusted to 5 or less, dehydration and condensation hardly occur, so that it is more preferable to enhance reproducibility of catalyst preparation.

In addition, a thickener may be added to these solutions to increase the viscosity of the mixture when the raw material solutions are mixed, and the particle size of the powder obtained by spray drying can be controlled.

In the method of the present invention, two or more kinds of solutions containing these catalyst components are mixed in the shortest possible time and spray-dried immediately.

Mixing method is commonly used stirring mixing, ultrasonic mixing,
A method using a line mixer, a static mixer, or the like is employed. The shorter the mixing time, the better. Although it depends on the temperature at the time of mixing, it is usually within a range of several minutes or at most several tens of minutes.

The temperature during mixing is not particularly limited, but is usually around room temperature.

The mixture is spray dried immediately. The method and conditions for spray drying can be directly applied to those commonly used in this field, and are not particularly limited.

Spray-dried powder is calcined, molded as needed, 400-7
Bake for about 1 to 20 hours at a temperature of 50 ° C.

The catalysts are used in fixed beds as granules or shaped bodies, but can also be used in moving or fluidized beds.

The catalytic gas phase oxidation reaction according to the present invention comprises, as a raw material gas composition, 1 to 10% by volume of propylene, secondary propanol, isobutylene or tertiary butanol, 3 to 20% by volume of molecular oxygen and 70 to 90% by volume of a diluent gas. This is carried out by introducing a mixed gas into the above-mentioned catalyst at a space velocity of 300 to 5000 / hr under a temperature range of 250 to 450 ° C. and a pressure of normal pressure to 10 atm.

Air is usually used as molecular oxygen, but pure oxygen may be used.

An inert gas such as nitrogen or carbon dioxide is used as the diluent gas. Further, a part of the non-condensable gas contained in the reaction gas may be circulated and used.

It is active to use water vapor as a diluent gas,
It is preferable to increase selectivity. In that case, the water vapor in the source gas is usually added up to 60% by volume.

〔Example〕

The present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 While heating and stirring 12,000 ml of water, ammonium molybdate 1
272 g and then 43 g of cesium nitrate were dissolved, and 1110 g of silica sol having a concentration of 20 wt% was further added to prepare solution A.

A solution B was prepared by dissolving 1396 g of cobalt nitrate and 702 g of ferric nitrate in 1800 ml of water.

571.4 g of bismuth nitrate was dissolved in a nitric acid aqueous solution consisting of 150 ml of 60% nitric acid and 1500 ml of water to obtain a liquid C.

Solution A 1200ml / min, Solution B 180ml / min, Solution C 165ml / m
The mixture was supplied to the line mixer at "in", continuously mixed, and the mixed solution at the outlet of the line mixer was spray-dried as it was.

The dried powder is calcined, formed into a cylinder having a diameter and height of 5 mm, and fired in air at 550 ° C. for 10 hours to obtain Mo / Bi / Fe /
Mixture 9 of oxides with Co / Cs atomic ratio of 12 / 2.0 / 3.0 / 8.0 / 0.4
A catalyst consisting of 0% by weight and 10% by weight of silica was obtained.

The obtained catalyst (40 ml) was charged into a 3/4 inch steel reaction tube, and a raw material gas composition comprising 6% by volume of isobutylene, 12% by volume of oxygen, 15% by volume of steam, and the remaining 67% by weight of nitrogen, and a reactor bath temperature of 350% The reaction was carried out under standard conditions of 1000C and space velocity of 1000 / hr, and the initial performance of the catalyst was evaluated.

After initial performance evaluation, 2 days under the conditions of forced gas degradation of 10 wt% isobutylene, 25 vol% oxygen, 20 vol% steam, and the remaining 45 vol% nitrogen, raw material gas composition, reactor bath temperature 420 ° C, space velocity 30,000 / hr. After the reaction, the reaction was returned to the standard conditions, and the stability of the catalyst was evaluated.

 Table 1 shows the evaluation results.

Example 2 In order to confirm that there was no variation in catalyst performance, a catalyst was prepared in the same manner as in Example 1, and the performance was evaluated.
The results are shown in Table 1.

Comparative Examples 1 to 5 Liquids A, B and C having the same composition as in Example 1 were prepared in order to clarify the variation in catalyst performance by the conventional method. Solution B and Solution C are sequentially dropped into Solution A, and the mixture is added at 60 ° C. for 5 hours.
After aging under agitation, a catalyst was prepared in the same manner as in Example 1 except for spray drying, and the performance was evaluated. The results are shown in Table 1.

Examples 3 to 5 Catalysts composed of a mixture of oxides having the atomic ratios shown in Table 2 and silica were prepared in the same manner as in Example 1, and the performance was evaluated. The results are shown in Table 2.

Comparative Examples 6 to 8 A catalyst comprising a mixture of oxides having the atomic ratios shown in Table 1 and silica was prepared in the same manner as in Comparative Example 1, and the performance was evaluated. The results are shown in Table 2.

Example 6 A catalyst composed of a mixture of oxides having the atomic ratios shown in Table 1 and silica was prepared in the same manner as in Example 1, and the isobutene in the raw material gas at the time of performance evaluation was changed to propylene. The operation was performed in the same manner as in Example 1 except that the temperature was changed to 320 ° C.
The results are shown in Table 2.

Comparative Example 9 A catalyst comprising a mixture of oxides having the atomic ratios shown in Table 1 and silica was prepared in the same manner as in Comparative Example 1. The same operation as in Comparative Example 1 was carried out except that the isobutene in the raw material gas at the time of performance evaluation was changed to propylene, and the reactor bath temperature was changed to 320 ° C. The results are shown in Table 2.

From the results of the above Examples and Comparative Examples, the following can be understood.

The variation between catalyst preparation lots was smaller for the catalyst according to the method of the present invention. (Examples 1, 2 and Comparative Examples 1 to 5) Comparing the initial performance and the performance after forced deterioration of the catalysts having the same composition, the catalyst according to the method of the present invention was superior. (Examples 1, 2 and Comparative Examples 1 to 5, Example 3 and Comparative Example 6, Example 4 and Comparative Example 7, Example 5 and Comparative Example 8, Example 6 and Comparative Example 9) [Effect of the Invention] A catalyst having excellent catalytic activity, acrolein or methacrolein selectivity, and excellent catalyst stability can be prepared with good reproducibility.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C07C 45/37 C07C 45/37 47/22 47/22 J // C07B 61/00 300 C07B 61/00 300 (58) Investigated field (Int. .Cl. ⁶ , DB name) C07C 47/22 C07C 45/35-45/39 B01J 23/88 B01J 27/04-27/18 C07B 61/00 WPI / L (QUESTEL)

Claims (6)

(57) [Claims] 1. A method according to claim 1, wherein propylene, secondary propanol, isobutylene or tertiary butanol is represented by the general formula: Moa Bib Fec Xd Ye Zf Og (where X is at least one element selected from Ni and Co; Is one or more elements selected from K, Rb, Cs and Tl, and Z is W, Be, Mg, S, Ca, Sr, Ba, Te, Se, Ce,
It represents one or more elements selected from Ge, Mn, Zn, Cr, Ag, Sb, Pb, As, B, P, Nb, Cu, Cd, Sn, Al, Zr, Ti and Si. a, b,
c, d, e, f, and g represent the atomic ratio of each element. Based on a, when a = 12, b = 0.1-10, c = 0.1-20, d
= 2 to 20, e = 0.01 to 2, f = 0 to 4, and g is the number of oxygen atoms necessary to satisfy the valence of each component. In the presence of a catalyst containing the composition represented by the formula (1), when producing acrolein or methacrolein by gas phase catalytic oxidation using molecular oxygen, the catalyst component was divided into two or more types to form a solution. Thereafter, a method for producing acrolein or methacrolein, comprising using a catalyst obtained by using a dry powder obtained by spray-drying immediately without mixing and aging the respective solutions, as a raw material. 2. When the solution containing the catalyst component is mixed, the pH is 5
The method of claim (1) wherein an acid is added to said solution such that: 3. The method according to claim 1, wherein an aqueous solution containing a molybdenum compound and an alkali metal compound or a tellurium compound is used as one of the solutions containing the catalyst component. 4. The method according to claim 1, wherein an aqueous solution containing an iron compound and one or more metal compounds selected from cobalt and nickel is used as one of the solutions containing the catalyst component. Method 3). 5. The method according to claim 1, wherein an aqueous solution containing a bismuth compound is used as one of the solutions containing the catalyst component.
The method of (2), (3) or (4). 6. The method according to claim 1, wherein silica sol is used as the Si component.