JPH0920700A - Production of methacrolein and/or methacrylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain methacrolein and/or methacrylic acid in high selectivity and high yield by catalytic vapor phase oxidation using a specially prepared catalyst. SOLUTION: The catalyst of the formula, PaMobVcBidXeYfZgOh (P is phosphorus; Mo is moybdenum; V is vanadium; Bi is bismuth; O is oxygen; X is arsenic, antimony, silicon, boron, germanium and tellurium; Y is potassium, cesium, rubidium and thallium; Z is chromium, manganese, iron, cobalt, nickel, copper, aluminum and gallium, etc.; a, b, c, d, e, f, g and h are each an atomic ratio, in the case of b=12, a, d and e are each ≠0 and <=3 and c, f and g are each 0-3 and h is determined from valence of individual elements and their ratios) is prepared by making a slurry mixture of a molybdenum compound with a bismuth compound at first then mixing them with other materials. The isobutane is catalytically oxidized in vapor phase using molecular oxygen.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing methacrolein and / or methacrylic acid by vapor phase catalytic oxidation of isobutane using molecular oxygen in the presence of a catalyst. Specifically, it relates to a method for producing methacrolein and / or methacrylic acid using a catalyst according to a specific preparation method.

[0002]

2. Description of the Related Art A method for producing methacrylic acid from isobutylene or tertiary butanol via methacrolein by two-step oxidation is well known and has already been industrially practiced. Although it is significantly less reactive than isobutylene or tert-butanol, it has the same carbon skeleton as these and is cheaper, but isobutane is used as a raw material, and gas phase catalytic oxidation is performed using molecular oxygen in the presence of a catalyst. Depending on methacrolein and /
Or, regarding the method of producing methacrylic acid, in recent years,
A method using a catalyst containing phosphorus-molybdenum Keggin-type heteropolyacid having phosphorus as a hetero atom and molybdenum as a poly atom as a main component has been proposed.

Several attempts have been proposed in the past to improve the performance by adding a metal element such as bismuth to the heteropolyacid catalyst. JP-A-62-132832, JP-A-63-145249 and JP-A-2-
Japanese Patent No. 42034 discloses a catalyst prepared by using 12-molybdophosphoric acid as a raw material and adding an aqueous bismuth nitrate solution to this aqueous solution.

JP-A-3-20237 discloses a catalyst prepared by using ammonium paramolybdate as a raw material and adding various metal element raw materials such as ammonium metavanadate and cesium nitrate to this aqueous solution. Regarding bismuth, there is no clear description about the bismuth raw material, its addition timing, and addition method.

JP-A-4-59739 discloses that molybdenum trioxide, vanadium pentoxide, phosphoric acid, etc. are used as raw materials.
Although a catalyst prepared by adding another metal element raw material after heating under reflux is disclosed, there is no clear description about the bismuth raw material, its addition timing, and the addition method.

JP-A-3-238051 discloses a detailed study on a bismuth raw material, a method for dissolving the bismuth raw material, and a method for adding bismuth in a reaction for producing methacrylic acid by oxidizing methacrolein using a similar catalyst. Has been done. According to this, when preparing a bismuth-containing heteropolyacid-based catalyst, the performance of the produced catalyst varies greatly depending on the bismuth raw material and the method of adding bismuth.
Further, it is described that when preparing the catalyst, it is preferable to add a nitric acid solution of bismuth nitrate and / or bismuth oxide to a mixed solution containing catalyst components such as phosphorus, molybdenum, vanadium and copper.

[0007]

However, in the presence of the bismuth-containing heteropolyacid catalyst prepared by the conventional method described above, isobutane is subjected to vapor phase catalytic oxidation using molecular oxygen to produce methacrolein and / or methacrylic acid. The method for producing methacrolein does not necessarily have sufficient selectivity for methacrolein and methacrylic acid.

[0008]

Means for Solving the Problems As a result of intensive studies on the method for producing methacrolein and / or methacrylic acid from isobutane with high selectivity, the present inventors have found that
Among the catalyst raw materials, first, a molybdenum raw material and a bismuth raw material are mixed to form a slurry, and then by using a bismuth-containing heteropolyacid catalyst prepared by mixing other metal element raw materials, methacrolein and The inventors have found that methacrylic acid can be produced and have completed the present invention.

That is, the present invention has the general formula PaMobV
cBidXeYfZgOh (In the formula, P is phosphorus, Mo is molybdenum, V is vanadium, Bi is bismuth, O is oxygen, and X is at least one selected from the group consisting of arsenic, antimony, silicon, boron, germanium, and tellurium. Element, Y is at least one element selected from the group consisting of potassium, cesium, rubidium and thallium, Z is chromium, manganese, iron, cobalt, nickel, copper, aluminum, gallium, indium, tin, zinc, cerium. , At least one element selected from the group consisting of yttrium and tungsten, and having subscripts a, b, c, d, e,
f, g and h represent atomic ratios of the respective elements, and when b = 12, a, d and e are values of 3 or less not including 0, c, f,
g represents a value of 3 or less including 0, and h represents a value determined by the valence and atomic ratio of each element. In the method of producing methacrolein and / or methacrylic acid by vapor-phase catalytic oxidation of isobutane in the presence of a heteropolyacid catalyst represented by the formula (1), a molybdenum raw material and a bismuth raw material are first selected from catalyst raw materials. A method for producing methacrolein and / or methacrylic acid, which comprises using a catalyst prepared by mixing raw materials to form a slurry and then mixing other metal element raw materials.

The catalyst composition used in the present invention is a known heteropolyacid catalyst represented by the above general formula, and specific examples thereof include the following compositions (excluding oxygen). _{P 0.5-2 Mo 12 V 0.05-2 Bi 0.01-2} As 0.01-2 Cu 0-1 Cs 0-2 P 0.5-2.5 Mo 12 V 0.05-2 Bi 0.01-2 Sb 0.01-3 Ni 0-1 K 0 _-2 P _1-2 Mo ₁₂ V _0.05-2 Bi _0.01-3 Sb _0.01-3 Co _0-2 Rb _0-2.5 P _0.5-2 Mo ₁₂ V ₂ Bi _0.01-2.5 Zn _0-3 Tl _0-1 P _{0.5 -2 Mo 12 V 0.05-2 Bi 0.01-2 As} 0.01-2 Sn 0-3 Cs 0-2

The phosphorus raw material used for preparing the catalyst is
Phosphoric acid, metaphosphoric acid, phosphorous acid, sodium phosphate, sodium hydrogenphosphate, etc., molybdenum trioxide, molybdic acid, ammonium paramolybdate, sodium molybdate, etc. Vanadium, ammonium metavanadate, sodium vanadate, etc. are used. Moreover, as the bismuth raw material, bismuth oxide, bismuth nitrate, bismuth sulfate, bismuth chloride, bismuth oxalate, or the like is used. As the X component, the Y component, and the Z component, respective nitrates, phosphates, oxides, etc. are used.

Regarding the catalyst preparation method, among the catalyst raw materials,
There is no particular limitation except that the molybdenum raw material and the bismuth raw material are first mixed to form a slurry and then other components are added. For example, there is a method in which molybdenum trioxide and bismuth oxide are heated for a long time, an aqueous solution in which phosphoric acid, arsenic acid, copper nitrate, and cesium nitrate are dissolved is added, vanadium pentoxide is added to this solution, and the solution is heated again. In addition, an ammonium paramolybdate aqueous solution and a bismuth nitrate aqueous nitric acid solution are mixed to form a slurry, and then an aqueous solution in which phosphoric acid, nickel nitrate, and potassium nitrate are dissolved is mixed, and antimony trioxide and vanadium pentoxide are added and heated. There is a way to do it. In this method, a nitric acid aqueous solution of bismuth nitrate may be added to the ammonium paramolybdate aqueous solution, or an ammonium paramolybdate aqueous solution may be added to the nitric acid aqueous solution of bismuth nitrate. Further, an ammonium paramolybdate aqueous solution and a nitric acid aqueous solution of bismuth nitrate are mixed to form a slurry, and an ammonium metavanadate aqueous solution is added to this, and then phosphoric acid, cobalt nitrate, and an aqueous solution in which rubidium nitrate is dissolved are mixed,
There is also a method of adding antimony trioxide to this solution and heating again. Water-insoluble metal oxides such as vanadium pentoxide and antimony trioxide are generally added last and heated. The obtained slurry can be evaporated to dryness and then calcined to obtain a predetermined catalyst.

The gas phase catalytic reaction of isobutane is usually carried out under the following conditions. The isobutane concentration in the raw material gas used for the reaction is about 1 to 85 mol%, preferably about 3 to 70 mol%.

A suitable molar ratio of molecular oxygen to isobutane is about 0.05 to 4.0, preferably about 0.1 to 3.5. As a supply source of molecular oxygen, air, pure oxygen, oxygen-enriched air, or the like is used.

About 3 to 30 water vapor is contained in the reaction raw material gas.
It is preferably contained in the range of mol%. Water vapor not only serves as a diluent for avoiding the explosive range and removing the heat of reaction, but also has a favorable effect on the activity, selectivity of the reaction, and thus on the catalyst life.

The raw material gas may contain a rare gas, nitrogen, carbon monoxide, carbon dioxide and the like. Further, even if isobutylene is contained in the raw material, isobutylene is converted to methacrolein or methacrylic acid as in isobutane.

Unreacted isobutane can be used as fuel, but it can also be recovered and recycled. Methacrolein can also be converted to methacrylic acid by recovering and recycling it. When pure oxygen or oxygen-enriched air is used, unreacted oxygen is preferably recovered and reused.

The reaction temperature can be selected in the range of about 250 to 450 ° C, preferably about 270 to 400 ° C. The reaction pressure can be widely selected from reduced pressure to increased pressure, but usually about 1
00-400 kPa, preferably about 100-200 kP
It is performed in the range of a.

The method of the present invention can be carried out in any reaction type such as fixed bed, moving bed, fluidized bed and the like. When the reaction is carried out in a fluidized bed, it is possible to use a raw material gas containing no oxygen to carry out an oxidation reaction of isobutane with oxygen in the catalyst, and the catalyst may be reoxidized with an oxygen-containing gas in another reactor. it can. Further, when the catalyst is used in a fixed bed system, there is no particular limitation on the space velocity, but it is industrially disadvantageous because productivity is reduced if the space velocity is too small, and conversely, if the space velocity is too large, Since the reaction activity decreases, the reaction temperature must be raised. Usually about 400-5000h
^-1 , preferably in the range of about 600 to 2000 h ^-1 .

The catalyst can be used in the form of being supported on a carrier or diluted and mixed. Examples of the carrier or diluent include silica, alumina, silica-alumina, magnesia, titania, zeolite, zirconia, and silicon-carbite, and there is no limitation on the amount of the catalyst to be supported or the dilution and mixing ratio with the diluent. The shape of the catalyst is tablet,
Rings, balls, extruded products, etc. are not particularly limited. The molding method can be performed by a known method such as compression molding, extrusion molding, spray drying granulation and the like.

The reaction product gas is cooled and condensed, and the products are separated and purified into respective products by operations such as extraction and distillation.

[0022]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. The conversion rate (%) and the selectivity rate (%) are respectively expressed by the following equations. Isobutane conversion (%) = (number of moles of reacted isobutane) /
(Mole number of supplied isobutane) x 100 Methacrolein selectivity (%) = (Mole number of methacrolein formed)
÷ (Number of moles of reacted isobutane) × 100 Methacrylic acid selectivity (%) = (Number of moles of methacrylic acid formed)
÷ (number of moles of reacted isobutane) × 100

Example 1 (Catalyst preparation) The composition excluding oxygen was P_1.5Mo₁₂V_0.5B
i_0.3As_0.4Cu_0.3Cs_1.4Heteropolyacid type
The catalyst was prepared by the following method. Ion-exchanged water 22
85% orthophosphoric acid [H_ThreePO_Four] 21.0
1 g, copper phosphate [Cu_Three(PO_Four)_Two・ 3H_TwoO] 5.33
g, cesium nitrate [CsNO _Three] 38.20g, 60% hi
Acid aqueous solution [H_ThreeAsO_Four] Add 13.24g and bring to 40 ° C
The solution was held and dissolved by stirring to obtain a uniform aqueous solution (solution A). S
Ion-exchanged water 33 in the reactor with jacket made of Tenres
0.09 g was charged and the temperature was kept at 40 ° C. there
Ammonium paramolybdate [(NH_Four)₆Mo₇O_{twenty four}・
4H_TwoO] 296.28 g was added and dissolved by stirring. This
70% nitric acid [HNO] in 30.52 g of deionized water_Three]
4.94 g, bismuth nitrate [Bi (NO_Three)_Three・ 5H
_Two[O], 20.36 g was added, and the resulting mixture was stirred and mixed.
A slurry was obtained (Liquid B). Inject all the amount of solution A into solution B and allow it to settle.
After depositing the powder to form a slurry, vanadium pentoxide [V
_TwoO_Five] Add 6.36g and run steam on the jacket
And heat to 120 ° C. for 17 hours for aging treatment,
The water was evaporated in a dryer at 120 ° C. Drying at this stage
Solid matter is X-ray diffraction, so-called Dawson type heteropoly acid
It was a structure. For 100 parts of dried solid crushed in a mortar,
After adding 26 parts of water and 4 parts of glass fiber and kneading, the mold was
It is extruded and used to form a product with a diameter of 3 mm and a length of about 5 mm.
Obtained the form. After drying it at 90 ° C, it was placed in nitrogen at 435 ° C.
Baked for 3 hours. The catalyst at this stage is the infrared absorption spectrum.
And X-ray diffraction show that cubic Keggin-type heteropolyacid structure
It was a structure.

(Reaction) 6 g of this catalyst was filled in a Pyrex glass reaction tube having a diameter of 15 mm, and isobutane 6.5 was added.
A raw material gas composed of mol%, oxygen 15.5 mol%, nitrogen 63 mol% and steam 15 mol% was supplied. The reaction pressure was 152 kPa and the contact time was 5.4 seconds. The reaction product was analyzed by gas chromatography. As a result of detailed examination of the reactor wall temperature of 330 to 350 ° C., the selectivity of methacrolein and methacrylic acid at the isobutane conversion rate of 25% were 2.5% and 42.6%, respectively.

Comparative Example 1 (Catalyst Preparation) A heteropolyacid catalyst having the same composition as in Example 1 was prepared by the following method. Deionized water 194.
85% orthophosphoric acid [H ₃ PO ₄ ] 21.03 in 50 g
g, copper phosphate _{[Cu 3 (PO 4) 2} · 3H 2 O] 5.33
g, cesium nitrate [CsNO ₃ ] 38.20 g, and a 60% arsenic acid aqueous solution [H ₃ AsO ₄ ] 13.24 g were added, and the mixture was maintained at 40 ° C. with stirring to dissolve it to obtain a uniform aqueous solution (solution A). Ion-exchanged water 33 in a reactor with stainless steel jacket
0.91 g was charged and the temperature was kept at 40 ° C. Ammonium paramolybdate [(NH ₄ ) ₆ Mo ₇ O ₂₄
4H ₂ O] 296.30 g was added and dissolved by stirring (B
liquid). After pouring the whole amount of the solution A into the solution B to form a precipitate and making it into a slurry, 6.36 g of vanadium pentoxide [V ₂ O ₅ ] was added, and then 30.48 g of ion-exchanged water was added to 70% nitric acid.
[HNO ₃ ] 4.93 g, bismuth nitrate [Bi (NO ₃ ) ₃
5H ₂ O] 20.36 g was added and an aqueous solution in which it was dissolved was added. Steam was poured into the jacket and heated to 120 ° C., and after aging treatment for 17 hours, water was evaporated in a dryer at 120 ° C. The dried product at this stage had a so-called Dawson type heteropolyacid structure by X-ray diffraction. 20 parts of water and 4 parts of glass fiber were added to 100 parts of the dried product crushed in a mortar and kneaded, followed by extrusion using a mold to obtain a molded product having a diameter of 3 mm and a length of about 5 mm. This was dried at 90 ° C. and then calcined in nitrogen at 435 ° C. for 3 hours.
From the infrared absorption spectrum and the X-ray diffraction, the catalyst at this stage had a cubic Keggin-type heteropolyacid structure.

(Reaction) 6 g of this catalyst was reacted in the same manner as in Example 1. When the conversion of isobutane is 25%, the selectivity of methacrolein and methacrylic acid are 2.9 each.
% And 39.6%.

Comparative Example 2 (Catalyst Preparation) Heteropolyacid catalyst having the same composition as in Example 1
Was prepared by the following method. Ion-exchanged water 201.
67g with 85% orthophosphoric acid [H_ThreePO_Four] 21.00
g, copper phosphate [Cu_Three(PO_Four)_Two・ 3H_TwoO] 5.33
g, cesium nitrate [CsNO _Three] 38.20g, 60% hi
Acid aqueous solution [H_ThreeAsO_Four] Add 13.25g and bring to 40 ° C
The solution was held and dissolved by stirring to obtain a uniform aqueous solution. This and Io
70% nitric acid [HNO_Three] 4.93
g, bismuth nitrate [Bi (NO_Three)_Three・ 5H_TwoO] 20.
Add 37 g and mix with stirring to obtain a slurry
(A liquid). Io in a reactor with a stainless steel jacket
Charge 330.70g of exchanged water and keep the temperature at 40 ° C
did. Ammonium paramolybdate [(NH_Four)₆
Mo₇O _{twenty four}・ 4H_TwoO] 296.31 g was added and dissolved by stirring.
It was allowed to dissolve (solution B). After injecting the entire amount of solution A into solution B,
Vanadium iodide [V_TwoO_Five] Add 6.36g and cover
Pour steam into the oven and heat it to 120 ° C, and then perform aging treatment 1
After 7 hours, evaporate the water in a dryer at 120 ° C.
Was. The dry matter at this stage is a so-called doso by X-ray diffraction.
It had a heteropolyacid structure. Dry solid crushed in a mortar
To 100 parts, add 25 parts water and 4 parts glass fiber
After kneading, extruding using a mold, diameter 3mm,
A molded catalyst raw material having a length of about 5 mm was obtained. Dry it at 90 ° C
After drying, it was baked in nitrogen at 435 ° C. for 3 hours. Touch at this stage
The medium is a cubic system based on infrared absorption spectrum and X-ray diffraction.
It had a Keggin-type heteropolyacid structure.

(Reaction) 6 g of this catalyst was reacted in the same manner as in Example 1. When the conversion of isobutane is 25%, the selectivity of methacrolein and methacrylic acid are 2.5 each.
% And 37.2%.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location // C07B 61/00 300 C07B 61/00 300

Claims (1)

[Claims] 1. The general formula PaMobVcBidXeYf
ZgOh (wherein P is phosphorus, Mo is molybdenum, V is vanadium, Bi is bismuth, O is oxygen, and X is at least one selected from the group consisting of arsenic, antimony, silicon, boron, germanium, and tellurium. Element, Y is at least one element selected from the group consisting of potassium, cesium, rubidium and thallium, Z is chromium, manganese, iron, cobalt, nickel, copper, aluminum, gallium, indium, tin, zinc, cerium. , At least one element selected from the group consisting of yttrium and tungsten, and having subscripts a, b, c, d, e,
f, g and h represent atomic ratios of the respective elements, and when b = 12, a, d and e are values of 3 or less not including 0, c, f,
g represents a value of 3 or less including 0, and h represents a value determined by the valence and atomic ratio of each element. In the method of producing methacrolein and / or methacrylic acid by vapor-phase catalytic oxidation of isobutane in the presence of a heteropolyacid catalyst represented by the formula (1), a molybdenum raw material and a bismuth raw material are first selected from catalyst raw materials. A method for producing methacrolein and / or methacrylic acid, which comprises using a catalyst prepared by mixing raw materials to form a slurry and then mixing other metallic element raw materials.