KR101558941B1

KR101558941B1 - Process For Producing Methacrolein And/Or Methacrylic Acid

Info

Publication number: KR101558941B1
Application number: KR1020107008636A
Authority: KR
Inventors: 타츠히코 구라카미; 아츠시 수도; 토시타케 코지마
Original assignee: 니폰 가야꾸 가부시끼가이샤
Priority date: 2007-11-06
Filing date: 2008-10-17
Publication date: 2015-10-08
Also published as: JP5130562B2; CN101848883B; KR20100075514A; CN101848883A; WO2009060704A1; JP2009114119A

Abstract

[PROBLEMS] To provide a method for producing methacrolein and / or methacrylic acid capable of maintaining high yield and effective selectivity over a long period of time.
[Solution]
Tertiary butanol and / or isobutylene is used as a raw material, and this is supplied to a reaction tube filled with an oxidation catalyst so as to have two exothermic peaks in the flow direction of the reaction tube, and the raw material is partially oxidized in the presence of molecular oxygen Characterized in that in the method for producing methacrolein and / or methacrylic acid, Tm-Tb? 15 占 폚, where Tm is the minimum temperature of the exothermic peaks of the two oxidation catalyst layers and Tb is the reactor temperature Methacrolein and / or methacrylic acid.

Description

TECHNICAL FIELD The present invention relates to a process for producing methacrolein and / or methacrylic acid,

The present invention relates to a process for the production of methacrolein and / or methacrylic acid.

A method of producing methacrolein and / or methacrylic acid in the presence of molecular oxygen by using tertiary butanol and / or isobutylene as a raw material and by a stationary phase catalytic oxidation reaction is already known and various proposals have been made have.

Patent Document 1 (Japanese Patent Application Laid-open No. 4-217932) discloses a method for producing methacrolein and / or methacrylic acid by filling a catalyst so that the occupation volume in the reaction tube becomes smaller toward the gas flow direction . In Patent Document 2 (Japanese Patent Application Laid-open No. Hei 6-192144), a catalyst comprising an inert carrier and a catalytically active component supported thereon is charged so that the amount of supported catalyst is increased along the gas flow direction, and methacrolein and / A process for producing an acid is described. Patent Document 3 (Japanese Patent No. 2934267) discloses a method for preparing a catalyst by controlling the amount of alkali metal and thallium in the catalyst component by controlling the catalytic activity and charging the catalyst so that the activity increases along the gas flow direction have. Patent Document 4 (Japanese Patent Application Laid-Open No. 2002-212127) discloses a method of providing two or more high-temperature zones in the catalyst layer in which there is no portion exceeding 50 캜 in difference from the reactor temperature and the difference is 15 to 50 캜 have. Patent Document 5 (Japanese Patent Application Laid-Open No. 2003-252820) discloses a method in which the difference between the maximum peak temperature and the minimum peak temperature in the catalyst layer is 20 占 폚 or less.

These inventions improve catalyst life, reaction yield and the like by suppressing heat generation due to oxidation of a raw material, pay attention to the highest temperature in the catalyst layer, and improve the catalyst life and reaction yield by reducing the temperature. Obviously, a certain degree of effect can be obtained, but further improvement in the yield is required as compared with the yield of production of acrolein and / or acrylic acid from propylene by the same catalyst.

As a result of intensive studies based on such facts, the present inventors have found out that the yield can be remarkably improved by controlling the minimum temperature of exothermic peaks, and that the yield can be obtained stably over a long period of time. And has reached the completion of the invention.

That is,

(1) Use of tertiary butanol and / or isobutylene as a raw material is fed to a reaction tube filled with an oxidation catalyst so as to have two exothermic peaks in the gas flow direction of the reaction tube, In the method for producing methacrolein and / or methacrylic acid by oxidizing, it is characterized in that Tm-Tb? 15 占 폚 when the minimum value of the temperature between exothermic peaks of two oxidation catalyst layers is Tm and the reactor temperature is Tb Or methacrylic acid and / or methacrylic acid.

(2) a method of producing methacrolein and / or methacrylic acid, characterized in that two exothermic peaks are obtained by diluting the catalyst layer on the inlet side of the raw material gas with an inert material.

According to the present invention, methacrolein and / or methacrylic acid are obtained in high yield over a long period of time.

The oxidation catalyst used in the present invention may be a catalyst known in the art if it is a catalyst used for obtaining methacrolein and / or methacrylic acid by gas phase catalytic oxidation of tertiary butanol and isobutylene.

As the preferable catalyst, there can be mentioned a catalyst containing a composite oxide represented by the following general formula as a catalytically active component:

Mo _a Bi _b Fe _C Co _d X _e Y _f o _h

In this formula,

Mo, Bi, Fe and Co represent molybdenum, bismuth, iron and cobalt,

X is at least one element selected from an alkali metal or Tl,

Y represents at least one element selected from the group consisting of Ni, Sn, Zn, W, Cr, Mn, Mg, Sb, Ce and Ti,

b = 0.1-10, c = 0.1-10, d = 1-10, e = 0.01-2, f = 0-2 and h are the values determined by the oxidation states of the respective elements, to be.

As the alkali metal, Cs is particularly preferable.

The production method of the oxidation catalyst and the raw materials are not particularly limited, and can be produced by using the methods and raw materials generally used for the production of such catalysts. And optionally grinding, firing and the like.

The shape of the oxidation catalyst is not particularly limited. For example, shapes such as circumferential shape, tablet shape, spherical shape, and ring shape can be appropriately selected in consideration of operating conditions. However, spherical supports, Or a supported catalyst having a particle size of 3 to 6 mm on which a catalytically active component is supported.

In the present invention, two kinds of catalysts having different activities are prepared, and they are separately charged into the reaction tube without mixing them, thereby forming two oxidation catalyst layers in the direction of the reaction tube gas flow. Accordingly, the exothermic peak in the reaction tube is usually two. In general, it is preferable to fill the catalyst so that the activity becomes higher in the direction of the raw gas flow. If necessary, a preheating layer may be provided on the raw material gas inlet side, and a dehydrating layer may be provided when tertiary butanol is used as a raw material. The material to be filled in the preheating layer or dewatering layer is preferably silica, alumina, titania, or silica-alumina. By providing a dehydration layer, the difference between the tertiary butanol and isobutylene raw materials can be made negligible.

The control of the catalytic activity can be carried out by a known method. For example, there is a method in which the firing temperature of the catalyst, the method of changing the catalyst composition, and the method of diluting the catalyst layer (on the inlet side of the raw material gas) with an inert material are preferred. In the present invention, the inert material means a substance having an activity of 0 to 20% when the activity of the catalyst used for the oxidation reaction is taken as 100%.

The two types of catalysts having different activities thus obtained are charged such that Tm-Tb? 15 when the minimum temperature between two exothermic peaks is Tm and the reactor temperature is Tb. Various factors such as concentration, composition, space velocity, reaction tube diameter, reaction pressure, and heat-releasing ability of the reactor affect the Tb and Tm. Therefore, by computer simulation and the like, And the ratio of the charging lengths of the different catalyst layers are optimized. Tm-Tb is more preferably 20 DEG C or more.

A thermocouple is installed in the reaction tube in the gas flow direction, the temperature is measured at an interval of about 10 cm, Tm is obtained from a plot of the obtained catalyst bed temperature in the Y axis and the catalyst filling length in the X axis. When measured at intervals of 10 cm or more, accurate data can not be obtained in some cases.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, the conversion rate, the yield and the selectivity were calculated according to the following equations.

(%) = (Molar number of reacted tertiary butanol or isobutylene) / (supplied tertiary

Number of moles of butanol or isobutylene) X 100

Methacrolein yield (%) = (number of moles of produced methacrolein) / (amount of tert-butanol

Or the number of moles of isobutylene) X 100

Methacrylic acid yield (%) = (number of moles of methacrylic acid produced) / (amount of tertiary butanol

Or the number of moles of isobutylene) X 100

Effective selectivity (%) = (methacrolein yield + methacrylic acid yield) / (conversion of raw materials)

X 100

Example 1

(Preparation of catalyst)

While heating and stirring 12,000 ml of distilled water, 3,000 g of ammonium molybdate and 55.2 g of cesium nitrate were dissolved to obtain an aqueous solution (A). Separately, 2,782 g of cobalt nitrate, 1,144 g of ferric nitrate and 412 g of nickel nitrate were dissolved in 2,300 ml of distilled water, and 1,167 g of bismuth nitrate was dissolved in 1,215 ml of an aqueous solution (B) and acidic nitric acid (292 ml) (C). The aqueous solution (A) was mixed with the aqueous solution (A) while stirring the aqueous solution (A) with vigorous stirring, and the resulting suspension was dried using a spray drier, and the resulting powder was calcined at 460 ° C for 5 hours, A fired powder (D) was obtained. The compositional ratio of the catalytically active component excluding oxygen was Mo = 12, Bi = 1.7, Fe = 2.0, Co = 6.75, Ni = 1.0, and Cs = 0.20 in atomic ratio.

Thereafter, the pre-fired powder (D) was carried in a proportion of 45% by weight based on the catalyst after being molded into a silica-alumina mixture inert carrier (particle size 4.0 mm). The thus-obtained molded product was calcined at 520 DEG C for 5 hours to obtain an oxidation catalyst (E).

(Oxidation reaction test)

A jacket for circulating the molten salt as a heating medium, and a silica-alumina sphere having a diameter of 5 mm as a dehydrated layer of tertiary butanol from the inlet of the raw material gas of a stainless steel reactor having an inner diameter of 23 mm and equipped with a thermocouple for measuring the catalyst layer temperature, A diluting catalyst 90 cm in which the oxidizing catalyst (E) and the silica-alumina mixture inert carrier were mixed at a weight ratio of 4: 1 as the first layer (raw material gas inlet side) of the oxidation catalyst layer, The catalyst (E) was charged in the order of 225 cm, and the reactor temperature Tb was set to 345 캜. Here, the raw material molar ratio of isobutylene: oxygen: nitrogen: water = 1: 2: 10: The tert-butanol, air, gas, set the nitrogen, so that the supply amount of water by 1.6 space velocity of 1,000 h ^-1 And the reaction was conducted. As a result, the conversion of raw material was found to be 99.6%, methacrolein yield was 81.07%, methacrylic acid yield was 3.59%, and effective selectivity was 85.02% when 200 hours passed after the initiation of the reaction. The temperature in the catalyst layer was set to a temperature of 410 DEG C for the first layer of the oxidation catalyst layer, an exothermic peak temperature of 389 DEG C for the second layer of the oxidation catalyst layer, a minimum temperature Tm of 377 DEG C and Tm- .

Example 2

The reaction of Example 1 was continued for 6,000 h while controlling the reactor temperature Tb so that the conversion of the raw material was 99.5%. The yield of methacrolein, methacrylic acid yield, methacrylic acid yield was 3.74% and 84.82%, respectively. The temperature in the catalyst layer was 348 DEG C, the exothermic peak temperature of the first oxidation catalyst layer was 399 DEG C, the exothermic peak temperature of the second oxidation catalyst layer was 377 DEG C, the minimum temperature Tm between the two exothermic peaks was 370 DEG C, Tm -Tb = 22 占 폚.

Example 3

The reaction of Example 1 was continued for 12,000 h while controlling the reactor temperature Tb so that the conversion of the raw material was 99.5%. The yield of methacrolein, the yield of methacrylic acid and the selectivity to methacrylic acid were 4.04% and 84.70%, respectively. The temperature in the catalyst layer was 355 DEG C, the exothermic peak temperature of the first layer of the oxidation catalyst layer was 408 DEG C, the exothermic peak temperature of the second layer of the oxidation catalyst layer was 384 DEG C, the minimum temperature Tm between the two exothermic peaks was 380 DEG C, -Tb = 25 占 폚.

Example 4

The reaction was carried out in the same manner as in Example 1 except that the inner diameter of the reaction tube filled with the catalyst in Example 1 was 21 mm and the space velocity was 1,200 h ^-1 . Over the course of 300 hours after the initiation of the reaction, the conversion of the starting material was 99.5%, the yield of methacrolein was 80.2%, the yield of methacrylic acid was 3.77%, and the effective selectivity was 84.4%. The temperature in the catalyst layer was 352 DEG C, the exothermic peak temperature of the first layer of the oxidation catalyst layer was 403 DEG C, the exothermic peak temperature of the second layer of the oxidation catalyst layer was 375 DEG C, the minimum temperature Tm between the two exothermic peaks was 370 DEG C, Tb = 18 占 폚.

Comparative Example 1

The reaction was carried out in the same manner as in Example 1, except that the diluting catalyst in which the oxidation catalyst (E) and the silica-alumina mixture inert carrier were mixed in a weight ratio of 2: 1 as the first catalyst layer in Example 1 was used. Over the course of 300 hours after the initiation of the reaction, the conversion of the raw material was 99.5%, the yield of methacrolein was 79.4%, the yield of methacrylic acid was 3.66%, and the effective selectivity was 83.5%. The temperature in the catalyst layer was 351 DEG C, the exothermic peak temperature of the first layer of the oxidation catalyst layer was 370 DEG C, the exothermic peak temperature of the second layer of the oxidation catalyst layer was 385 DEG C, the minimum temperature Tm between the two exothermic peaks was 365 DEG C, Tb = 14 占 폚.

As described above, in the case where the reactor temperature Tb and the exothermic peak temperature are set to Tm-Tb? 15 占 폚, the high yield and effective selectivity can be maintained over a long period of time Able to know.

Claims

Tertiary butanol and / or isobutylene is used as a raw material, and this is supplied to a reaction tube filled with an oxidation catalyst so as to have two exothermic peaks in the flow direction of the reaction tube, and the raw material is partially oxidized in the presence of molecular oxygen Characterized in that, in the method for producing methacrolein and / or methacrylic acid, Tm-Tb? 15 占 폚, where Tm is the minimum temperature of the exothermic peaks of the two oxidation catalyst layers and Tb is the reactor temperature ,
Wherein the oxidation catalyst is a catalyst containing a complex oxide represented by the following general formula as a catalytically active component,
Mo _a Bi _b Fe _C Co _d X _e Y _f o _h
In this formula,
Mo, Bi, Fe and Co represent molybdenum, bismuth, iron and cobalt,
X is at least one element selected from an alkali metal or Tl,
Y represents at least one element selected from the group consisting of Ni, Sn, Zn, W, Cr, Mn, Mg, Sb, Ce and Ti,
b = 0.1-10, c = 0.1-10, d = 1-10, e = 0.01-2, f = 0-2, h are the values determined by the oxidation states of the respective elements, Lt;
Wherein said alkaline metal is Cs, and / or methacrylic acid.

The method for producing methacrolein and / or methacrylic acid according to claim 1, wherein two exothermic peaks are obtained by diluting the catalyst layer on the inlet side of the raw material gas with an inert material.