JPH03294239A - Production of acrolein and acrylic acid - Google Patents

Abstract

PURPOSE:To obtain the subject compound in high yield by preparing plural specific molybdenum-based catalysts having different activity under specific conditions in subjecting propylene to vapor phase catalytic oxidation, dividing each catalyst layer to >=2 layers and charging said catalysts under specific conditions. CONSTITUTION:The subject compound is produced by vapor phase catalytic oxidation of propylene with molecular oxygen or a molecular oxygen-containing gas using a fixed bed and multitube-type reactor. In said process, a specific Mo-based catalyst is used and species and/or quantity of at least a species of element selected from alkaline earth metal in the catalyst component is varied to prepare plural catalysts having different activity and simultaneously, catalyst layers in every reaction tubes are divided to >=2 layers in the tube axis direction to provide plural reaction zones. Then, the above-mentioned plural catalysts having different activity are charged in the tubes so as the activity to become higher from inlet part to exit part of raw material gas, thus heat reserve at a hot spot part in the catalyst layer is suppressed, yield of the aimed compound is increased and deterioration of the catalysts is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing acrolein and acrylic acid by gas phase catalytic oxidation of propylene with molecular oxygen or a molecular oxygen-containing gas.

(Prior Art) Numerous proposals have been made regarding catalysts used when producing acrolein and acrylic acid by high-temperature gas phase oxidation of propylene. These mainly concern the selection of the components constituting the catalyst and their ratios.

Since the above oxidation reaction is a reaction accompanied by extremely high heat, a large amount of heat is accumulated in the catalyst layer. Especially in locally abnormally high temperature zones called hot spots, the yield not only decreases due to excessive oxidation reaction, but also due to heat load. Catalyst life is greatly affected by catalyst deterioration. Therefore, in industrial implementation, heat accumulation in hot spots becomes a serious problem, especially when the concentration of starting materials is increased or the space velocity is increased in order to increase productivity (hereinafter referred to as "high-load reaction conditions"). (In some cases, heat accumulation in hot spots tends to be significant.) At present, there are considerable restrictions on reaction conditions.

Therefore, suppressing heat accumulation in this hot spot is important for industrially producing acrolein and acrylic acid in high yields, and also for suppressing catalyst deterioration and enabling stable operation over long periods of time. This is very important. Particularly in the case of a molybdenum-based catalyst, it is important to prevent heat accumulation in hot spots because the molybdenum component is easily sublimed.

Several proposals have been made in the past as a method of suppressing heat accumulation in hot spots.
Japanese Patent No. 36740 proposes that the catalyst be shaped into a ring. This publication describes that in a shaped catalyst commonly used as a catalyst for the oxidation of propylene, isobutylene, and /' or t-butanol, the shape of the shaped catalyst is changed from a spherical or cylindrical shape to a ring shape to improve heat storage at hot spots. It is said that this method has a great effect on improving yields because it can suppress excessive oxidation reactions. However, although this method is effective in reducing the heat load, it cannot be said to yield sufficiently satisfactory results, particularly under high load reaction conditions.

In addition, a method of dividing the catalyst layer to provide multiple reaction zones, filling the multiple reaction zones with catalysts with different activities, and subjecting them to the oxidation reaction is also used, for example, as a method for producing acrolein and acrylic acid from propylene. , special public official 1986-
It is known from Publication No. 38331.

However, in this catalyst, the activity m1ni is achieved by changing the amount of alkali metal added, but as can be seen from the fact that the amount of the alkali metal component added is very small compared to other components, the effect of addition is Therefore, great care must be taken when preparing the catalyst, and it cannot necessarily be said to be a practical and appropriate catalyst from the standpoint of controlling catalyst activity.

Additionally, JP-A-51-127013 discloses a method for producing unsaturated aldehydes and acids from propylene and isobutylene, in which a supported catalyst and a shaped catalyst having essentially the same composition are combined. .

This catalyst system is also not sufficiently satisfactory for use in industrial practice.

(Problems to be Solved by the Invention) One object of the present invention is to provide a method for producing acrolein and acrylic acid in high yield by vapor phase catalytic oxidation of propylene.

Another object of the present invention is to suppress heat accumulation in hot spots in the catalyst layer when producing acrolein and acrylic acid by vapor phase catalytic oxidation of propylene, thereby improving the yield of acrolein and acrylic acid. It is an object of the present invention to provide a method for producing acrolein and acrylic acid, which prevents deterioration of the catalyst and enables stable use of the catalyst over a long period of time.

Another object of the present invention is to suppress heat accumulation in hot spots in the catalyst layer when producing acrolein and acrylic acid by gas-phase catalytic oxidation of propylene under high-load reaction conditions, and to recover acrolein and acrylic acid. To provide a method for producing acrolein and acrylic acid, which improves productivity, prevents catalyst deterioration, allows stable use of the catalyst over a long period of time, and significantly improves productivity.

(Means for Solving the Problem) The present inventors manufactured a plurality of specific molybdenum-based catalysts with different activities, and on the other hand, divided the catalyst layer into two or more layers to provide a plurality of reaction zones, I learned that the above objective could be achieved by filling these multiple reaction zones with a plurality of molybdenum catalysts with different activities so that the activity becomes higher from the raw material gas inlet to the outlet. Based on this, the present invention has been completed.

That is, the present invention provides a method for producing acrolein and acrylic acid by vapor phase catalytic oxidation of propylene using molecular oxygen or a molecular oxygen-containing gas using a fixed bed multitubular reactor. - Formula (1
) % formula % (In the formula, Mo is molybdenum, W is tungsten, Bi is bismuth, Fe is iron, A is at least one element selected from nickel and cobalt, and B is at least one element selected from alkali metals and thallium. element, C is at least one element selected from alkaline earth metals, D
is at least one element selected from phosphorus, tellurium, antimony, tin, cerium, lead, niobium, manganese, amber, and zinc; E is at least one element selected from silicon, aluminum, titanium, and zirconium; O is at least one element selected from silicon, aluminum, titanium, and zirconium; Represents oxygen, and also a, b, c, d,
e, f, g, h, 1 and X are each MO
5W, B1. Fe, A, BSC, D,
Representing the number of atoms of E and O, and when a=12, b
=o~10, c=0.1~10, d=0.1~20, e
=2~20. f=0~10, g=0.001~10, h
=0-4, i=0-30. x = a numerical value determined by the oxidation state of each element) using a composite oxide expressed by (b) a plurality of catalyst layers in each reaction tube divided into two or more layers in the tube axis direction; (c) In the catalyst of (a) above, a plurality of catalysts with different activities prepared by changing the type and/or amount of the group C element in formula (1) are added from the raw material gas inlet to the reaction zone. The present invention relates to a method for producing acrolein and acrylic acid, characterized in that the filling is performed so that the activity becomes higher toward the outlet.

The present invention will be explained in detail below.

The catalyst used in the present invention is a composite oxide represented by the above formula (1). There are no particular restrictions on the preparation method and raw materials for this catalyst, and it can be prepared using methods and raw materials commonly used for producing rA catalysts of this type.

In the present invention, - I! I and packed with these multiple catalysts in a specific arrangement, catalysts with different activities can be easily prepared by changing the type and/or amount of group C elements in general formula (I). . That is, at least one selected from alkaline earth metals such as beryllium, magnesium, calcium, and strontium.
The type and/or amount of the element in the species (however, - formula (1)
(within the atomic ratio defined by g), catalysts with different activities can be obtained.

The catalyst used in the present invention is composed of elemental components represented by formula (1), and the object of the present invention is achieved by combining these elemental components. Among these elemental components, the tungsten component is particularly It is effective in improving the catalytic activity, and by using it in combination with the C group element, a significant improvement in the catalytic activity is observed without reducing the selectivity of the catalyst.

The addition ratio of the phosphorus component is 0 to 10, preferably 0.5 to 10, when the molybdenum component is 12.

In addition, "activity" in this invention means the conversion rate of a starting material.

The catalyst used in the present invention may be molded by a conventional molding method, such as an extrusion molding method or a tablet molding method.
In addition, the composite oxide represented by the general formula (I) as a catalyst component can be selected from silicon carbide, alumina, zirconium oxide,
It may be supported on an inert carrier that is generally used as a carrier, such as titanium oxide.

The shape of the catalyst used in the present invention is not particularly limited and may be spherical, cylindrical, ring-shaped, etc. In particular, when a ring-shaped catalyst is used, heat accumulation in hot spots is prevented, yield is improved, A ring-shaped catalyst is preferably used in the present invention because it provides various advantages such as prevention of catalyst deterioration and reduction of pressure loss in the catalyst layer.

The ring-shaped catalyst is a ring with an outer diameter of 3 to 10 mm, a length of 0.5 to 2 times the outer diameter, and an inner diameter of the through hole in the length direction of 0.5 to 2 times the outer diameter. catalysts are preferably used.

In the present invention, the catalyst layer in each reaction tube is divided into two parts in the tube axis direction.
A plurality of reaction zones are provided by dividing into layers or more, and a plurality of catalysts having different activities are arranged in these reaction zones so that the activity increases successively from the inlet to the outlet of the raw material gas. That is, the catalyst with the lowest activity is placed at the inlet, while the catalyst with the highest activity is placed at the outlet. By arranging a plurality of catalysts with different activities in this way, it is possible to suppress heat accumulation in hot spots and obtain the target product with high selectivity.

The more the catalyst layer is divided, the easier it is to control the temperature distribution of the catalyst layer, but industrially the desired effect can be sufficiently obtained by dividing the catalyst layer into 2 to 3F+. Also,
The splitting ratio cannot be determined unambiguously because it depends on the composition and shape of the catalyst in each layer.
It may be selected appropriately so as to obtain the overall optimum activity and selectivity.

The gas phase catalytic oxidation reaction in the present invention may be an ordinary single flow method or a recycling method, and can be carried out under conditions generally used for this type of reaction. For example, propylene 1 A mixed gas consisting of ~10% by volume, 3 to 20% by volume of molecular oxygen, 0 to 60% by volume of water vapor, and 20 to 80% by volume of an inert gas such as nitrogen or carbon dioxide is poured onto the catalyst at 250% to 200% by volume. Temperature range of 450℃, under pressure of normal pressure to 10 atm, space velocity 300 to 5000 hr
= (STP).

According to the method of the present invention, particularly under high-load reaction conditions aimed at increasing productivity, for example, under conditions of higher raw material concentration or higher space velocity, compared to conventional methods, remarkable results are obtained. is obtained.

(Effects of the Invention) In the present invention, a plurality of specific molybdenum-based catalysts having different activities are filled into a plurality of divided catalyst layers so that the activity becomes higher from the raw material gas inlet to the outlet. As a result, (a) acrolein and acrylic acid can be obtained in high yield, (b) heat accumulation in the hot spot can be effectively suppressed, (C) excessive oxidation reaction in the hot spot can be prevented, The desired acrolein and acrylic acid can be obtained in high yields; (d) deterioration of the catalyst due to heat load is prevented and the catalyst can be used stably for a long period of time; (e) high raw material concentration; Even under high-load reaction conditions such as high space velocity, the desired acr3L/yne and acrylic acid can be obtained in high yields, resulting in effects such as a significant increase in productivity.

Furthermore, by using a ring-shaped catalyst, in addition to the above-mentioned effects, it is also possible to obtain effects such as (f) power consumption can be reduced due to a reduction in pressure loss in the catalyst layer.

Therefore, the method of the present invention is extremely useful for industrial production of acrolein and acrylic acid.

(Example) below, The present invention will be explained in more detail with reference to Examples.

In addition, conversion rate, The selectivity and total single stream yield are is defined by the formula.

Conversion rate (mol%) = Selectivity (mol%) = Produced acrolein or total single stream yield (mol%) Produced acrolein and Example 1 436 g of cobalt nitrate and 202 g of ferric nitrate were dissolved in 1000 IIl12 of water. Ta. Also, bismuth nitrate 2
43g of nickel nitrate and 291g of nickel nitrate were mixed with concentrated nitrogen [30g and water 1
20a9 was dissolved in a nitric acid aqueous solution.

Separately, 1059 g of ammonium paramolybdate and 265 g of ammonium paratungstate were dissolved in 3000 g of water while heating, and the above two separately prepared aqueous solutions were added dropwise to the obtained aqueous solution and mixed, and then 55 g of cesium nitrate was dissolved. An aqueous solution prepared by dissolving .8 g of barium nitrate and 13.1 g of barium nitrate in 400+aI2 of water, and further 203 g of 20% by weight silica sol were sequentially added and mixed.

The suspension thus obtained was heated and stirred, evaporated to dryness, and then molded into a cylinder with an outer diameter of 6 mm and a length of 3 mm. ) was obtained. The composition of this catalyst (1) is MO12W2B i+Fe+C03N i2c SIl in atomic ratio excluding oxygen.
,l! 6B a@, +S i 1.3s.

In the method for preparing catalyst (1) above, the catalyst (1) was prepared in the same manner as in catalyst (1) except that the amount of barium nitrate was changed to 65.3 g.
2) was prepared. The formation of this catalyst (2) is MO12W2B i +F e +C03N i 2CS in atomic ratio excluding oxygen.
@, 116B as5S 11.35.

Regarding the activity of the above catalysts (1) and (2), please refer to the comparison r! As is clear from the results of 4] and 2, catalyst (2) has higher activity than catalyst (1).

The raw material gas inlet of a steel reaction tube having a diameter of 25.4 mm was filled with the above catalyst (1) 750d, while the raw material gas outlet was filled with the above catalyst (2) 750-.

Propylene 8% by volume, oxygen 14.1% from the inlet of the reaction tube
A mixed gas having a composition of 25% by volume of water vapor and 52.9% by volume of nitrogen was introduced, and the reaction was carried out at a reaction temperature of 310°C and a space velocity of 1600 hr-' (STP).

The results are shown in Table 1.

Comparative Example 1 In Example 1, the reaction was carried out in the same manner as in Example 1, except that catalyst (1) alone was charged at 1,500 kg without using catalyst (2). The results are shown in Table 1.

Comparative Example 2 The reaction was carried out in the same manner as in Example 1, except that the catalyst (1) was not used and only the catalyst (2) was charged at 1,500 kg. The results are shown in Table 1.

Comparative Example 3 Catalyst (3) was prepared in the same manner as catalyst (1) in Example 1, except that the amount of barium nitrate used was 39.2 g. The formation of this catalyst (3) is MOI2W2B i +F e+C in atomic ratio excluding oxygen.
03N r 2CSe, 56Ba@, 3si1.3s.

In Example 1, the reaction was carried out in the same manner as in Example 1, except that only 1500 d of the catalyst (3) was filled into the reaction tube.

The results are shown in Table 1.

From the results in Table 1, the activity of catalyst (1) is very low, while catalyst (2) has high activity but low selectivity. ), (2
) It is understood that the total single-stream yield is high in the catalyst system of the present invention in which the following are combined, and the desired acrolein and acrylic acid can be obtained in high yield.

Furthermore, when comparing catalyst (3) having an intermediate composition between catalyst (1) and catalyst (2), and the catalyst system of the present invention in which catalysts (1) and (2) are combined, catalyst (3) In this case, the total single-stream yield was low, and furthermore, the temperature difference (ΔT) between the reaction temperature and the maximum temperature of the catalyst layer was very large, so it is thought that the catalyst deteriorated significantly due to heat load. That is, it is understood that the effects of the present invention cannot be achieved even if a single catalyst (3) having substantially the same composition as the catalyst system of the present invention is used alone.

Example 2 The catalyst ( Catalyst (4) and catalyst (5) were prepared in the same manner as in 1illi1 of 1).

The compositions of catalyst (4) and catalyst (5) in atomic ratio excluding oxygen were as follows.

Catalyst (4) MOtzWzB il, 2Fe+cosNa@, +Ca
*, ts i +, as Catalyst (5) Mo+2W2B j+, 2Fe+cosNa@, +Ca
@, es i +, 3s Example 1 except that 750 d of catalyst (4) was filled in the inlet of the raw material gas and 750 d of catalyst (5) was filled in the outlet of the raw gas.
The reaction was carried out in the same way. The results are shown in Table 1.

Comparative Example 4 The reaction was carried out in the same manner as in Example 2, except that the catalyst (4) alone was charged for 1500 d without using the catalyst (5). The results are shown in Table 1.

Comparative Example 5 The reaction was carried out in the same manner as in Example 2, except that the catalyst (5) alone was charged at 1,500 kg without using the catalyst (4). The results are shown in Table 1.

Comparative Example 6 Catalyst (6) was prepared in the same manner as catalyst (4) in Example 2, except that the amount of calcium nitrate was changed.

The composition of the catalyst (6) is MOI2W in atomic ratio excluding oxygen.
2B il, 2Fe+cOsNa*, +Ca@, aS
i +, 3s.

Hereinafter, catalyst (6) is replaced with catalyst (4) and catalyst (5).
The reaction was carried out in the same manner as in Example 2, except that 1,500 μg of 1,500 μg of ) was charged. The results are shown in Table 1.

Example 3 Catalyst (1) of Example 1 was prepared in the same manner as catalyst (1) except that potassium hydroxide was used instead of cesium nitrate, barium was added as a C group element, and strontium nitrate was used. Catalyst (7) and catalyst (8) were prepared.

The compositions of catalyst (7) and catalyst (8) in atomic ratio excluding oxygen were as follows.

Catalyst (7) MOI2W2B i +F e+C03N 12Ks,
ssB al! , 1 catalyst (8) MOI2W2B i+Fe+CoxNi2 @, @8B
ae, below a, catalyst (7) 600+d at raw gas inlet
The reaction was carried out in the same manner as in Example 1 except that the outlet portion was filled with catalyst (8) 900-. The results are shown in Table 1.

Comparative Example 7 The reaction was carried out in the same manner as in Example 3, except that only the catalyst (7) was used at 150%.

Comparative Example 8 The results are shown in Table 1. The reaction was carried out in the same manner as in Example 3 except that only the catalyst (8) was used at 150%.

The results are shown in Table 1.

Comparative Example 9 Catalyst (9) was prepared in the same manner as catalyst (7) in Example 3, except that the amount of barium was changed.

The composition of the catalyst (9) is MOI2W in atomic ratio excluding vl Qin.
2B i +F e+C03N i 2K1. lIgB
&++,s.

In Example 3, the reaction was carried out in the same manner as in Example 3, except that only catalyst (9) was used.

The results are shown in Table 1.

Example 4 In the preparation of catalyst (1) of Example 1, tungsten,
The contents of cobalt, iron, and bismuth were changed, sodium and potassium were used as group C elements, and 6 g of titanium dioxide and 43 g of cerium dioxide were added, molded into a sphere, and closed and fired at 465°C under air circulation at 8 o'clock. Catalysts (10) and (11) were prepared in the same manner as catalyst (1) except that
and (12) were produced by yA.

The compositions of catalysts (10), (11) and (12) were as follows in atomic ratio excluding oxygen.

Catalyst (10) Mo+2W@, sB i +, sF e2c osN
am, + to *, ssCes, sS i +, zsT
i s, +sB &1.1 catalyst (II) Mo+2W@, 11B it, sF e2c osN
as, +Ks, ssCes, sS i l 3sT
i 1I68 am, 3 catalysts (12) Mo+2W@, sB i +, sF e2co
eN as, +Ks, -sCe@, sS i 1.3S
T i s, +s B as, s In a reaction tube with an inner diameter of 30 mm, a catalyst (] 0") is placed from the raw material gas intake side to the outlet side.
400d, catalyst (] 1) 400d and catalyst (12) 1
000-, and a mixed gas having the same composition as in Example 1 was introduced at a space velocity of 2000 hr-I (STP>) to carry out the reaction.The propylene conversion rate was 98.5 at a reaction temperature of 325°C.
The total single flow yield of acrylic acid and acrolein was 92.1 mol%. The results are shown in Table 1.

Comparative Example 10 The reaction was carried out in the same manner as in Example 4, except that instead of catalysts (10) to (12), only catalyst (10) was charged. The results are shown in Table 1.

Comparative Example 11 The reaction was carried out in the same manner as in Example 4, except that instead of catalysts (1o) to (12), only catalyst (11) was charged at 1800 kg. The results are shown in Table 1.

Comparative example] 2

Claims (3)

[Claims] (1) In a method for producing acrolein and acrylic acid by gas phase catalytic oxidation of propylene with molecular oxygen or molecular oxygen-containing gas using a fixed bed multi-tubular reactor, (a) as a catalyst, the following general formula is used: (I) Mo_aW_bBi_cFe_dA_eB_fC_gD
_hE_iO_x (wherein Mo is molybdenum, W is tungsten, Bi is bismuth, Fe is iron, A is at least one element selected from nickel and cobalt, and B is at least one element selected from alkali metals and thallium).
seed element, C is at least one element selected from alkaline earth metals, D is phosphorus, tellurium, antimony, tin,
At least one element selected from cerium, lead, niobium, manganese, arsenic and zinc, E is at least one element selected from silicon, aluminum, titanium and zirconium, O represents oxygen, and a, b, c
, d, e, f, g, h, i and x are respectively Mo
, represents the number of atoms of W, Bi, Fe, A, B, C, D, E and O, and when a=12, b=0 to 10, c=0
．． 1-10, d=0.1-20, e=2-20, f=0
~10, g=0.001~10, h=0~4, i=0~
(b) The catalyst layer in each reaction tube was divided into two or more layers in the tube axis direction. (c) In the catalyst of (a) above, a plurality of catalysts with different activities prepared by changing the type and/or amount of group C elements in general formula (I) are placed in multiple reaction zones at the raw material gas inlet. 1. A method for producing acrolein and acrylic acid, the method comprising filling the acrolein and acrylic acid so that the activity becomes higher from the outlet toward the outlet. (2) The method for producing acrolein and acrylic acid according to claim (1), wherein the number of reaction zones is 2 or 3. (3) The catalyst has an outer diameter of 3 to 10 mm and a length of 0.0 mm to the outer diameter.
5 to 2 times the inner diameter of the through hole in the length direction is 0.1 to the outer diameter
Claim (1) or (2) which is a ring-shaped catalyst of 0.7 times
) The method for producing acrolein and acrylic acid.