DE2311883C3 - Process for the production of acrylic acid by the oxidation of acrolein - Google Patents

Description

and oxygen exists In the DT-OS 19 24 496 is an acid content of 550 ppm (mol), based on acrylic

Process for the production of acrylic acid by oxy acid, while with the alkali metal-free catalyst

dation of acrolein with oxygen in the gas phase a propionic acid content of 130G ppm was obtained,

described, in which a catalyst is used, the propionic acid content in the product is

which in addition to oxygen, vanadium and molybdenum at least 5 use of the catalyst according to the invention

at least one further element contains. Finally, in borrowed is reduced, while in terms of acrylic acid

DT-OS 1618 744 describes a process in which no major differences are observed in the yield

the acrylic acid by oxidation of acrolein with the. In both cases the yield of acrylic

Oxygen is produced in the gas phase, at which an acid is about 70 mole percent, based on propylene.

Catalyst made from molybdenum, vanadium, tungsten and io The catalyst used according to the invention is

Oxygen is used. The presence of a prepared in a manner known per se, e.g. B. by

Alkali metal in the above-described cata- veneers of a water-soluble molybdate, such as

lysers is not mentioned. Ammonium molybdate, a water-soluble vanadate,

The invention accordingly relates to a water-soluble alkali process, such as ammonium vanadate, for the production of acrylic acid by means of oxy-metal salt, such as sodium nitrate, and optionally dation of acrolein in the presence of a molybdenum and a tungsten or antimony compound in the form of vanadium and containing oxygen on a catalyst applied to an aqueous solution or a powder, as well as to a silica carrier and in sets of a suitable carrier, such as highly disperse presence of water vapor at elevated temperature silica, evaporation of the mixture to dryness, in the gas phase, which is characterized in that ao comminution of the product obtained on a suitable propylene-containing acrolein or an acrolein obtained with the gas particle size and calcining at temperatures of 300 phase oxidation of propylene to 500 ⁰ C, preferably 350 to 450 ⁰ C, in the presence of a gas mixture with oxygen or free acid from Oxygen.

substance-containing gases in the presence of a catalyst The used to prepare the catalyst

sators oxidized, the composition of which - 25 starting compounds, z. B. the Moiybdat, are

see from the oxygen content - the empirical formula is not limited to the aforementioned compounds.

Mo VhTrAd ^ ^s all metal compounds can be used

that in the calcination step is a metal oxide or a

corresponds, in which Mo molybdenum, V vanadium, T complex metal oxide with the other metals resp.

Tungsten or antimony and A form an alkali metal form compounds.

as well as α the value 12, b a value from 0.5 to 6, The catalyst is either as granules or in

c a value from 0 to 6 and d a value from 0.01 to form tablets or pellets in a fixed bed

1.5 has. turns. It can also be in the form of small particles

The process is preferably used with a catalyst, a fluidized bed or a moving bed

using the specified empirical formula,

in which «/ has a value from 0.15 to 1.2. When working after continuous

The process according to the invention can be used in the first oxidation stage of any cat-

procedure (2) or (3) mentioned above can be applied. lysator are used, the propylene mainly

When applying the invention to the continuous to acrolein is oxidized.

The progress is to be made in this process in a more precise manner. In the first stage of oxidation, propylene that the yield of propionic acid decreases together with air or some other free acidification can, while at the same time using a high yield substance-containing mixture. Possibly of acrylic acid is obtained. the gas charge can also use steam

Of the alkali metals contained in the invention. The gas mixture entering the catalyst used in the first oxidation stage is particularly effective in decongesting. The other alkali metals, ie potassium, hold the acrolein formed, unreacted pro-lithium, rubidium and cesium are also active, oxygen, nitrogen, water vapor as well as sam. If the amount of alkali metal is too large, byproducts acrylic acid, acetic acid, carbon, the activity of the catalyst against acrolein oxidizes and carbon dioxide. The gas mixture is in the loren. On the other hand, when the amount of alkali metal to 50 second oxidation stage is small over that of the present invention, the catalyst is passed in terms of its catalyst. The contact time is usually insufficient with propylene, 0.5 to 10 seconds (NTP). The procedure is poisoned. In comparative experiments, in which a catalysis atm preferably carried out at temperatures of 250 to 35O ⁰ C and sator of the composition according to the invention and pressures from 0.5 to 10. Preferably, no alkali metal containing catalyst under 55 wise the reaction is carried out at a molar ratio of the same reaction conditions were used, oxygen to steam to acrolein of 0.5 to 5: 1 was obtained with the according to the invention used up to 20: 1.

Catalyst in the oxidation of the first oxy- The examples illustrate the invention. In the two

dation stage obtained gas mixture a propion play means:

acrylic acid formed (mol)

One step yield of acrylic acid ( %) = -: ~ ~; 7ΓΓΤΓ ' 100

^v propylene fed in (mole)

propionic acid formed (mol)
Propionic acid content (ppm) = _{acrylic acid formed (mol)} ' ¹⁰ '

example 1

A catalyst for the first oxidation stage is prepared according to Example 1 of Japanese Patent Publication No. 6 245/1969. This catalyst has the composition Ni ₄₁ SCO ₄ Fe ₁ Bi ₁ P ₀₁₀₈ Mo ₁₂ O ₅₂ . 140 ml of the catalyst are introduced into a reaction tube made of corrosion-resistant steel with an internal diameter of 20 mm. The tube is placed in a ^{potassium nitrate bath heated to 330 °} C., and a gas mixture of propylene, air and water vapor in a molar ratio of 1:12: 6 is introduced. The contact time is 6 seconds (NTP). 95.0% of the propylene fed into the first oxidation stage are converted, while the remaining 5% are contained in the gases emerging from the first oxidation stage. 83% of the converted propylene is converted into acrolein, while 6% is oxidized to acrylic acid. The remainder consists essentially of carbon dioxide, carbon monoxide and small amounts of acetic acid. The gas emerging from the first oxidation stage, which contains the remaining oxygen and nitrogen as well as water vapor, is passed directly into the second oxidation stage.

In the second oxidation stage, a catalyst is used which is prepared as follows: 66.1 g of ammonium paramolybdate, 1.33 g of sodium nitrate and 10.9 g of ammonium metavanadate are each dissolved in distilled water and mixed with one another. 40 g of highly disperse silica with an SiO, content of 21% are then stirred in. The mixture is heated with stirring and evaporated to dryness. The residue is pulverized to a particle size corresponding to a mesh size of 4.0 to 0.84 mm and calcined for ^{4 hours at 400 ° C. in a stream of air.} The catalyst has the composition Mo ₁₂ V ₃ Na _0-5 O ₄₃ . The carrier is silica. 177 are introduced into a stainless steel tube having an inner diameter of 20 mm, which is immersed in a heated at 270 ⁰ C Kaliumnitratschroelze ml of the catalyst. The acrolein-containing gas mixture emerging from the first oxidation stage is fed into the pipe. The one-step yield of acrylic acid is 71.0%. the

ίο content of unreacted propylene is 4.8%. 3% acrolein is formed as a by-product. The rest is mostly made up of carbon dioxide, carbon monoxide and acetic acid. The propionic acid content is 550 ppm.

¹ ^ Comparative example 1

The first oxidation stage is carried out as in Example 1. The one emerging from the first oxidation stage Gas is fed into the second oxidation stage.

ao directs. The conditions in the second oxidation stage are the same as in Example 1, but the sodium-free catalyst used in the second Oxidation stage of Example 1 was used. This catalyst thus has the composition

»5 Mo _n V ₃ O _43; Silica is used as the carrier. The one-step yield of acrylic acid is 72.2%. The content of unreacted propylene is 4.5%, and 3% acrolein is formed as a by-product. The propionic acid content is 1300 ppm.

Examples 2 to 8

Example 1 is repeated under the conditions given in Table I. The results are in Table I compiled.

Table I. example Catalyst composition Salt Mining Single Stage Propion

temperature yield of acidity

Acrylic acid

CQ (%) (ppm)

2 Mo ₁₁ V ₁ Li ₀₁₈ O ₄ , 270 70.5 670 3 Mo V _{1 n} Ke ₁₈ O _4, 270 70.7 590 4th Mo ₁₄ V ₈ Na ₀₁₄ O ₄ , 270 71.0 6OC 5 Mo ₁₁ V ₁ Na _0-16 O ₄ , 270 71.2 880 6th Mo ₁₁ V ₁ Na ₀₄ O ₄ , 270 66.5 500 7th Mo ₁₁ V ₁ RbCiO ₄ , 270 69.5 680 8th Mo ₁₁ V ₁ Cs ₀₁₈ O ₄ , 270 69.0 690

Ammonium metavanadate, 9.5 g ammonium parawolf

Example 9 ramat and 1.3 g of sodium nitrate are each in de

dissolved in distilled water, mixed together and

The first oxidation stage is mixed with 40 g of highly disperse silica as in Example 1 65. That carried out. In the second oxidation stage, a mixture is evaporated to dryness with stirring. Catalyst is used, which is prepared as follows: The residue becomes a grain size accordingly represents: 66.1 g ammonium paramolybdate, 10.9 g with a mesh size of 4.0 to 0.84 mm powder

and calcined in air at 400 ° C. for 4 hours. The catalyst has the composition

Mo ₁₂ V ₈₁₅ W ₁ Na ₀₁₅ O ₄₇ .

Silica serves as the carrier. This catalyst is used under the same conditions as in Example 1. The one-step yield of acrylic acid is 73.3%, the propionic acid content 570 ppm.

Comparative example 2

The process of Example 9 is repeated, but a catalyst of the composition Mo _lt V ₃ W _ll2 O _{47 is} used in the second oxidation stage. Silica serves as the carrier. The one-stage yield of acrylic acid is 75.2%, the propionic acid content is 1300 ppm.

Example 10

The first oxidation stage is carried out as in Example 1. In the second oxidation stage, a catalyst is used which is prepared as follows: 66.1 g of ammonium paramolybdate, 10.9 g of ammonium metavanadate and 1.3 g of sodium nitrate are each dissolved in distilled water and mixed with one another. The mixture is mixed with 14.2 g of antimony trioxide powder and 40 g of highly dispersed silica, heated with stirring and evaporated to dryness. The residue is pulverized to a particle size corresponding to the clear mesh size of 4.0 to 0.84 mm and calcined at 400 ° C. for 4 hours. The catalyst has the composition Mo ₁₂ V ₃ Sb ₃ Na ₀₁₅ O ₄₈ . Silica serves as the carrier. This catalyst is used according to Example 1 in the second oxidation stage. The one-stage yield of acrylic acid is 72.0%, the propionic acid content is 570 ppm.

Comparative example 3

The process of Example 10 is repeated, but a catalyst of the composition Mo ₁₂ V ₃ Sb ₃ O _{48 is} used in the second oxidation stage. Silica serves as the carrier. The one-stage yield of acrylic acid is 73.1%, the propionic acid content is 1300 ppm.

Examples 11-21

The first oxidation stage is carried out as in Example 1. The catalysts given in Table II are prepared according to Example 9 or Example 10 and used in the second oxidation stage. The reaction conditions, with the exception of the salt bath temperature, and the apparatus are the same as in Example 1. The results are shown in Table II.

Table II Example catalyst composition Salt bath single stage propion

temperature yield of acidity

Acrylic acid

(° Q (%) (ppm)

11th Mo ₁₁ V ₁ W _0-5 Na ₁ O ₄₀ 270 70.2 520 12th Mon ₁₁ V _1-5 W ₉₁₅ Kp ₁₈ O ₄₁ 280 72.1 540 13th Mo ₁₁ V ₄ W ₁ Na _0-5 O ₄ , 270 72.8 560 14th Mo ₁₁ V ₅ W ₁ Li ₁ O ₅₅ 270 71.9 610 15th 280 69.8 690 16 270 70.1 600 17th Mo ₁₁ V ₁ Sb _0-5 Na ₀₁₅ O ₄ , 270 71.9 590 18th MOuVMW ₄ ^ a ₁ Oi, 280 68.0 530 19th Mo ₀ V ₁ SbM ^ Os ₅ 280 68.5 580 120 Mo ₀ ViSb ₁ Na ^ O ₄₅ 270 67.5 900 21 Μο ,, ν, ^ .Λ ^, ^ Ρ « 270 60.0 300

Vergfcadis examples 4 to 24

DT-PS 19 08 965 have been produced. With the exception of the safe bath temperature, which is also given in the first oxidation level according to Example 1 65, Table QI, the reaction conditions: ¥ the second oxidation level satisfy the operating conditions given in the example in the catalyst loading conditions. The results and in table HLzaeamdiil according to DT-ÖS1924496 or the quantity. ^,

\ Q Zo 1 1
9 883 10 Propionic
acidity
(ppm) Table HI 1210 Comparative
example Catalyst composition Salt bath
temperature
( ⁰ C) Classify
yield at
Acrylic acid
(%) 1250 4th V / Mo / Ge = 15/80/5 280 68.6 1310 5 V / Mo / Pb = 15/80/5 260 64.2 1230 6th V / Mo / Mn = 15/80/5 260 63.7 1300 7th V / Mo / U = 15/80/5 260 65.0 1350 8th V / Mo / Cu = 15/80/5 260 64.4 1190 9 V / Mo / Au = 15/80/5 260 63.2 1170 10 V / Mo / Ba = 15/80/5 260 63.8 1250 11th V / Mo / Se = 15/80/5 260 62.3 1110 12th V / Mo / Co = 15/80/5 260 62.4 1320 13th V / Mo / Ag = 15/80/5 260 61.8 1250 14th V / Mo / Mg = 15/80/5 260 60.9 1330 15th V / Mo / B = 15/80/5 260 61.5 1130 16 V / Mo / Sr = 15/80/5 260 62.7 1270 17th V / Mo / Ca = 15/80/5 260 60.8 1180 18th V / Mo / Zn = 15/80/5 260 61.4 1310 19th V / Mo / Cd = 15/80/5 260 62.5 1350 20th Mo / W / Fe / V = 6/1 / 1.5 / 1 240 62.1 1250 21 Mo / W / V / Mn = 6/1 / 1.5 / 1.5 270 52.6 1340 22nd Mo / W / V / Ni = 6/1 / 1.5 / 1.5 270 49.2 1200 23 Mo / W / V / Mn / Cu = 6/1 / 1.5 / 0.75 / 0.75 270 55.2 24 Mo / W / V / Ni / Cu = 6/1 / 1.5 / 0.75 / 0.75 270 62.8

Ϋ1537

Claims (2)

Can be made of acrylic acid or its esters, a great influence on the quality claims. In experimental investigations with the aim of 1. Process for the production of acrylic acid with the formation of propionic acid as a by-product by oxidation of acrolein in the presence of a 5 to reduce the oxidation, it has been found that Molybdenum and vanadium as well as oxygen contain the unreacted in the first oxidation stage holding and on a silica support propylene, which is contained in the exhaust gases, in the brought catalyst and in the presence of a second oxidation stage in the presence of a main water pan at elevated temperature in the cataphase containing mainly molybdenum and vanadium, characterized in that io lysators is oxidized to propionic acid. Farther propylene-containing acrolein or a small amount of propylene are used in the first oxy-gas phase oxidation aerosol obtained from propylene is oxidized to propionaldehyde, which in the Linen-containing gas mixture with oxygen or free second oxidation stage to propionic acid, further oxy-oxygen containing gases in the presence of a dated. Oxidized catalyst, its composition 15 molybdenum-vanadium catalysts for the production - apart from the oxygen content - the empire of acrylic acid by gas phase oxidation of acroric Formula lein are z. B. in Japanese Patent Publication Mon V * TA <i lutions No. 1775/1966, 1662/1967, 12129/1969, ^a 12 886/1969 and 26287/1969 described. This kaca- corresponds, in which Mo molybdenum, V vanadium, ao lysatoren have a poor activity against T tungsten or antimony and A an alkali metal propylene in the case of the suitable for the oxidation of acrolein, and α the value 12, b a value of th reaction temperatures. For example, only 0.5 to 6, c will have a value of 0 to 6 and d will have a value of about 10% propylene under the reaction conditions of 0.01 to 1.5. oxidized, in which more than 90% acrolein is oxidized 2. The method according to claim 1, characterized in this way. The propylene is drawn in a small amount that d has a value of 0.15 to 1.2. Propionic acid oxidizes. So if acrylic acid is produced by the oxidation of propylene by the continuous process is to be and if 100% of the propylene is to be oxidized in the first 30 oxidation stage, then only fall small amounts of propionic acid. A 100% conversion however, the presence of propylene causes a large decrease in the selectivity to acrolein. Therefore must to avoid a reduction in the one-stage 35 yield of acrolein, the propylene conversion to one Value can be set from about 95 to 97%. As a result, 3 to 5% propylene is in the second oxy- Acrolein can be introduced through the oxidation of propylene. be asked. In the production of acrylic acid The invention is based on the object of providing a by catalytic gas phase oxidation of propylene 40 drive to the production of acrylic acid by oxyfaction essentially three processes are used: dation of propylene-containing acrolein in the presence a catalyst containing molybdenum and vanadium (1) The one-step oxidation process, in which sators at elevated temperatures in the gas phase Propylene is difficult to create in the presence of a catalyst, the catalyst being compared to propylene is oxidized indirectly to acrylic acid; 45 is deactivated to prevent the formation of propionic acid (2) a two-step process in which a first decrease. So there was the task of a catalytic oxidation stage Acrolein is manufactured and used to create sator for this process in which the Separation of by-products such as acrylic active centers of the catalyst versus acrolein acid, into a: second oxidation stage and propylene are different. The solution to this is oxidized; 50 task is based on the surprising finding that (3) a process in which in a first oxy- this catalyst by small amounts of an alkalidation stage mainly acrolein produced metal can be partially deactivated or poisoned, and in a second oxidation stage without removal. In GB-PS 9 03 034 there is a process for separation of by-products or exhaust gases from acrylic acid by vapor phase oxidation is further oxidized; this method is after- 55 of acrolein with oxygen using a referred to as a continuous process. Catalyst described, in addition to molybdenum and The catalytic gas phase oxidation of oxygen at least one further polyvalent metal, Acrylic acid made from propylene contains low levels of magnesium, such as vanadium, iron, cerium, titanium, nickel, antimony, gen of propionic acid. Propionic acid can be broken down from the tin, tungsten, and bismuth that contains it. In the US PS Acrylic acid according to both physical processes, such as 60 34 08 392, a process is described in which Distillation, as well as chemical processes only acrylic acid by oxidation of acrolein with acidic separate, since both compounds are practically produced in the presence of a ternary catalyst have the same physical properties, e.g. B. is made of molybdenum, vanadium, antimony has a similar boiling point and similar molecular and oxygen levels. In the DT-OS 20 38 763 is a Weight. Their chemical properties are also very well described in which acrylic acid is carried out similar, since they do not differ significantly in their chemical structure. However, practice phase in the presence of a ternary catalyst her-propionic acid and their esters, which are not polymerized, are made from molybdenum, vanadium, and antimony