Production of acrolein and / or acrylic acid from propylene with reduced amounts of high-boiling by-products

Abstract

The reactor for producing acrolein and / or acrylic acid from propylene includes an inlet for propylene to enter the reactor, an outlet for the reaction product to exit the reactor, and a catalyst bed disposed between the inlet and the outlet. The catalyst bed contains a molybdenum and bismuth-based mixed oxide catalyst. The catalyst CAT closest to the inlet of the reactor 入口 is the catalyst CAT closest to the reactor outlet 出口 , a smaller amount of maleic anhydride is produced relative to the total amount of acrolein and acrylic acid.

Description

[Technical Field]

[0001] The present invention relates to a catalyst bed and process for producing acrolein and / or acrylic acid from propylene. [Background technology]

[0002] Acrylic acid and its esters are important monomers for a variety of polymers, including coatings, adhesives, and superabsorbent polymers. Most acrylic acid is produced via a two-stage propylene oxidation process, in which propylene is first oxidized over a molybdenum (Mo) and bismuth (Bi)-based mixed oxide catalyst to form primarily acrolein, with acrylic acid being the minor product. This acrolein is then oxidized over a molybdenum and vanadium (V)-based mixed oxide catalyst to produce acrylic acid. The main by-products of the acrylic acid production process from propylene include carbon monoxide, carbon dioxide, acetic acid, formaldehyde, acetaldehyde, propionic acid, propionaldehyde, acetone, allyl alcohol, maleic acid (or maleic anhydride), benzaldehyde, benzoic acid, furfural, and phthalic acid. These by-products can be removed by distillation, extraction, melt crystallization, or a combination thereof. However, removing these by-products adds cost and complexity to the process.

[0003] U.S. Patent No. 9,440,904 discloses a process for producing acrolein and / or acrylic acid, or methacrolein and / or methacrylic acid, using two catalysts with different compositions stacked axially. In the two catalysts, the ratio of bismuth to molybdenum decreases from the gas inlet side to the gas outlet side of the reactor, and the ratio of iron to molybdenum increases from the gas inlet side to the gas outlet side.

[0004] There is a need for catalyst beds and processes that can reduce the amount of by-products formed during the production of acrolein and / or acrylic acid from propylene. Summary of the Invention

[0005] The present invention relates to a reactor and a method for producing acrolein and / or acrylic acid from propylene, and further to a reactor and a method for producing acrylic acid from acrolein.

[0006] According to one aspect of the present invention, a reactor for producing acrolein and / or acrylic acid from propylene includes an inlet for propylene to enter the reactor, an outlet for the reaction product to exit the reactor, and a catalyst bed disposed between the inlet and the outlet. The catalyst bed includes a molybdenum and bismuth-based mixed oxide catalyst. The catalyst CAT closest to the inlet of the reactor is 入口 is the catalyst CAT closest to the reactor outlet 出口 , a smaller amount of maleic anhydride is produced relative to the total amount of acrolein and acrylic acid.

[0007] Another aspect of the present invention involves a process for preparing acrolein and / or acrylic acid from propylene, comprising oxidizing propylene in a reactor comprising an inlet for propylene to enter the reactor, an outlet for reaction products to exit the reactor, and a catalyst bed disposed between the inlet and the outlet. The catalyst bed comprises a molybdenum and bismuth-based mixed oxide catalyst. The catalyst CAT closest to the inlet of the reactor 入口 is the catalyst CAT closest to the reactor outlet 出口 , a smaller amount of maleic anhydride is produced relative to the total amount of acrolein and acrylic acid. DETAILED DESCRIPTION OF THE INVENTION

[0008] As used herein, the terms "a," "an," "then," "at least one," and "one or more" are used interchangeably. The terms "comprise," "include," "contain," and variations thereof do not have a limiting meaning when these terms appear in the specification and claims. That is, for example, a mixture including a polymerization inhibitor can be interpreted to mean that the mixture includes at least one polymerization inhibitor.

[0009] As used herein, the recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). For purposes of the present invention, it should be understood that numerical ranges are intended to include and support all possible subranges subsumed within that range, consistent with what one of ordinary skill in the art would understand. For example, a range of 1 to 100 is intended to convey 1.1 to 100, 1 to 99.99, 1.01 to 99.99, 40 to 6, 1 to 55, etc.

[0010] As used herein, recitations of numerical ranges and / or values, including such recitations in the claims, can be read as including the term "about." In such cases, the term "about" refers to a numerical range and / or value that is substantially the same as that recited herein.

[0011] Unless stated to the contrary or implicit from context, all parts and percentages are by weight and all test methods are as of the filing date of this application. For purposes of United States patent practice, the contents of any referenced patent, patent application, or patent application publication are incorporated by reference in their entirety (or the equivalent United States version thereof is so incorporated by reference), particularly with respect to the disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and general knowledge in the art.

[0012] One aspect of the present invention relates to a reactor for producing acrolein and / or acrylic acid from propylene.

[0013] The reactor includes an inlet for propylene to enter the reactor, an outlet for reaction products to exit the reactor, and a catalyst bed disposed between the inlet and the outlet, the catalyst bed including a molybdenum and bismuth-based mixed oxide catalyst.

[0014] As used herein, the term "reaction product" includes the desired product, which includes acrolein and / or acrylic acid, as well as by-products of the reaction, which may include carbon monoxide, carbon dioxide, acetic acid, formaldehyde, acetaldehyde, propionic acid, propionaldehyde, acetone, allyl alcohol, maleic acid, maleic anhydride, benzaldehyde, benzoic acid, furfural, and phthalic acid.

[0015] Preferably, the molybdenum and bismuth based mixed oxide catalyst comprises a compound of formula I: Mo 12 Bi a X b Y c Z d O e Formula I During the ceremony, X is at least one element selected from the group consisting of iron, cobalt, and nickel; Y is at least one element selected from the group consisting of magnesium, calcium, strontium, barium, manganese, copper, zinc, cerium, boron, phosphorus, arsenic, tellurium, antimony, chromium, tungsten, sodium, potassium, rubidium, and cesium; Z is at least one element selected from the group consisting of silicon, aluminum, titanium, tin, and zirconium; a=0.1~2.0, b=1~12, c=0.01~3, d=0 to 20, e is based on the oxidation states of the other elements in the catalyst.

[0016] One objective of the present invention is to minimize the formation of by-products. Reaction by-products are typically removed by distillation, extraction, melt crystallization, or a combination thereof. By-products not only consume valuable propylene feedstock, but also affect the recovery rate of acrylic acid and the need to remove them to prepare a particular grade of acrylic acid. For example, when crude acrylic acid is distilled to produce overhead acrylic acid with reduced amounts of maleic anhydride or maleic acid, some acrylic acid must be left in the bottoms along with most of the maleic anhydride or maleic acid. For flocculant-grade glacial acrylic acid, which limits the amount of furfural or benzaldehyde to less than 1 ppm, a chemical scavenger, such as m-phenylenediamine, may be added to the crude acrylic acid to form high-boiling adducts with the high-boiling aldehydes that are removed in an additional step.

[0017] Without being bound by theory, it is believed that the heavy by-products are related to the formation of the intermediate 1,5-hexadiene. 1,5-Hexadiene is formed as an intermediate by-product when propylene is deprotonated to form an allyl group, which can then react with another allyl group to form 1,5-hexadiene. This reaction competes with the reaction of the allyl group to form acrolein.

[0018] [ka]

[0019] In the catalyst bed of the present invention, the molybdenum and bismuth-based mixed oxide catalyst CAT closest to the inlet of the reactor 入口 indicates the molybdenum and bismuth mixed oxide catalyst CAT closest to the reactor outlet. 出口 It is different from CAT. 入口 is CAT 出口 CAT produces less maleic anhydride with respect to acrolein and acrylic acid compared to 出口 Preferably, CAT 入口This means that they have the same or higher activity as CAT when measured independently of each other. 入口 is CAT 出口 This means that, at a propylene conversion equivalent to CAT 1, a smaller amount of maleic anhydride is produced compared to the total amount of acrolein and acrylic acid in the reaction product. As used herein, "equivalent propylene conversion" means that, at a propylene conversion equivalent to CAT 1, a smaller amount of maleic anhydride is produced compared to the total amount of acrolein and acrylic acid in the reaction product. 入口 and CAT 出口 This means that the difference in propylene conversion between CAT and CAT is less than 5%. 入口 and CAT 出口 The difference in propylene conversion between the two is less than 3%, more preferably less than 2%. This can be quantitatively determined by setting up two identical experiments except for the catalyst and temperature and / or contact time to achieve equivalent propylene conversion, measuring the concentrations of maleic anhydride, acrolein, and acrylic acid in the reaction products, and calculating the ratio of maleic anhydride to the total amount of acrolein and acrylic acid according to the following formula:

[0020]

number

[0021] CAT 入口 and CAT 出口 To achieve different ratios of maleic anhydride compared to the total amount of acrolein and acrylic acid in the reaction product between 入口 and CAT 出口 may differ in at least one characteristic or variable selected from composition, size, shape, preparation method, carrier, concentration (e.g., amount of diluent), and the like.

[0022] For example, the manner in which a catalyst is prepared may result in different catalytic activities. Preparation methods may differ, for example, in the order of addition of components (or elements), mixing temperature and time, drying method, calcination temperature and time, atmosphere, etc. Two catalysts with the same nominal composition may have different catalytic activities and / or selectivities due to differences in their preparation methods.

[0023] The composition of the catalyst may vary based on the ratio of selected elements (eg, the molar ratio of bismuth to molybdenum), the addition or removal of elements, and the like.

[0024] The morphology of the catalyst or support may also alter catalytic activity and / or selectivity. For example, a catalyst formed on a spherical catalyst may have different catalytic activity / selectivity compared to a catalyst of similar composition formed in a ring shape.

[0025] Preferably, CAT 入口 and CAT 出口 varies based on the composition of the catalyst.

[0026] The catalyst bed is made of a molybdenum and bismuth mixed oxide catalyst. 入口 From CAT 出口 In the gradient composition, the catalyst closest to the reactor inlet, i.e., CAT 入口 is the catalyst closest to the reactor outlet, CAT 出口 The gradient composition may vary linearly between the inlet and outlet of the reactor, or may vary non-linearly between the inlet and outlet. This gradient composition may be achieved, for example, by varying the relative amounts of components within the catalyst. For example, the molar ratio of bismuth to molybdenum may remain relatively constant near the inlet of the reactor and then increase rapidly toward the outlet. Alternatively, the CAT 入口 and CAT 出口 The gradient between is the gradient in the composition of elements other than bismuth and molybdenum.

[0027] In another embodiment, the catalyst bed may contain two or more zones within the molybdenum and bismuth-based mixed oxide catalyst, each zone producing a different ratio of maleic anhydride compared to the total amount of acrolein and acrylic acid in the reaction product. For example, the zone closest to the inlet, i.e., CAT 入口 The molar ratio of bismuth to molybdenum in the zone closest to the reactor outlet, i.e., CAT 出口Alternatively, each zone in the catalyst may have a different chemical formula Mo 12 Bi a X b Y c Z d O e may have

[0028] The catalyst bed may have three or more zones, e.g., CAT1 (where CAT1 = CAT 入口 ), CAT2 etc. to CAT n (where CAT n =CAT 出口 where n is the number of zones), each zone containing a catalyst that produces a different ratio of maleic anhydride compared to the total amount of acrolein and acrylic acid in the reaction product. When the catalyst bed contains three or more zones within the molybdenum and bismuth-based mixed oxide catalyst, the zone closest to the reactor inlet (CAT1 or CAT2) is the zone closest to the reactor inlet. 入口 ) and the zone closest to the reactor outlet (CAT n or CAT 出口 ) for example, CAT2 to CAT n-1 The catalyst in the zone closest to the inlet (CAT1 or CAT 入口 ) is greater than the ratio of maleic anhydride to the total amount of acrolein and acrylic acid produced by the catalyst located in the zone closest to the reactor outlet (CAT n or CAT 出口 ) can produce a ratio of maleic anhydride to the total amount of acrolein and acrylic acid that is less than the ratio of maleic anhydride to the total amount of acrolein and acrylic acid produced by the catalyst in

[0029] Preferably, the catalyst bed comprises two or more zones within the molybdenum and bismuth based mixed oxide catalyst.

[0030] Preferably, the ratio of maleic anhydride to the total amount of acrolein and acrylic acid is in the range of 250 to 10,000 ppm, where the ratio of maleic anhydride to the total amount of acrolein and acrylic acid is calculated by the formula set forth above in terms of parts per million (ppm).

[0031] Preferably, the catalyst located nearest the inlet of the reactor produces maleic anhydride in an amount ranging from 250 to 5,000 ppm, more preferably from 250 to 4,000 ppm, based on the total amount of acrolein and acrylic acid.

[0032] Preferably, the catalyst located nearest the outlet of the reactor produces maleic anhydride in an amount ranging from 2,000 to 10,000 ppm, more preferably from 2,000 to 8,000 ppm, based on the total amount of acrolein and acrylic acid.

[0033] Another aspect of the present invention relates to a process for preparing acrolein from propylene, comprising oxidizing propylene in a reactor comprising an inlet for introducing propylene into the reactor, an outlet for the reaction products to exit the reactor, and a catalyst bed disposed between the reactor inlet and outlet, the catalyst bed comprising a molybdenum and bismuth-based mixed oxide catalyst as described above, the catalyst CAT being located closest to the reactor inlet. 入口 is the catalyst CAT located closest to the reactor outlet 出口 The process has a lower ratio of maleic anhydride to the total amount of acrolein and acrylic acid in the reaction product compared ...

[0034] Then, in a second step, acrolein in the reaction product can be selectively oxidized in the presence of oxygen in the gas phase over a second mixed metal oxide catalyst, the second mixed metal oxide catalyst having a different composition than the molybdenum and bismuth-based mixed oxide catalyst.

[0035] The second mixed metal oxide catalyst may be a solid catalyst containing oxides of molybdenum (Mo) and vanadium (V). The second mixed metal oxide catalyst may also contain at least one additional element selected from tungsten (W), copper (Cu), iron (Fe), antimony (Sb), and phosphorus (P). When the second mixed metal oxide catalyst contains at least one additional element, molybdenum and vanadium are the major metal elements present. Preferably, the second mixed metal oxide catalyst contains at least 40 wt. % molybdenum and vanadium, for example, at least 50 wt. %, at least 60 wt. %, or at least 70 wt. % molybdenum and vanadium, based on the total weight of the metals in the second mixed metal oxide catalyst.

[0036] The second mixed metal oxide catalyst can be any commercially available mixed metal oxide catalyst used in the oxidation of acrolein to acrylic acid.

[0037] In the selective oxidation reaction to form acrolein and / or acrylic acid, oxygen can be present in the form of purified oxygen, oxygen in air, or lattice oxygen of a mixed metal oxide catalyst. Preferably, the oxygen is from air or from the lattice oxygen of a mixed metal oxide catalyst.

[0038] Purification of the acrolein and / or acrylic acid can be achieved by one or more techniques known in the art, such as, for example, absorption using water or organic solvents, extraction, fractional distillation, or melt crystallization.

[0039] Desktop example The following prophetic examples illustrate the present invention but are not intended to limit the scope of the invention.

[0040] In the tubular reactor, a catalyst bed is positioned between the reactor inlet and the reactor outlet. The catalyst bed is composed of a molybdenum and bismuth-based mixed oxide catalyst containing two zones, with the first zone occupying approximately one-third of the volume of the catalyst bed and the second zone occupying approximately two-thirds of the volume of the catalyst bed. These catalysts are provided from different sources, have different compositions, and are manufactured by different processes, resulting in different maleic anhydride to acrolein / acrylic acid production ratios. The catalyst producing a lower maleic anhydride to total acrolein / acrylic acid production ratio has a ratio of approximately 2,500 ppm. The catalyst producing a higher maleic anhydride to total acrolein / acrylic acid production ratio has a conversion similar to that of the first catalyst, i.e., a ratio of approximately 4,300 ppm within 2%.

[0041] In a first experiment according to the present invention, a catalyst having a lower ratio of maleic anhydride to total acrolein / acrylic acid production was placed in a first zone closest to the inlet, and a catalyst having a higher ratio of maleic anhydride to total acrolein / acrylic acid production was placed in a second zone closest to the outlet.

[0042] In a second comparative experiment, a catalyst having a higher maleic anhydride to acrolein / acrylic acid production ratio was placed in a first zone closest to the inlet, and a catalyst having a lower maleic anhydride to acrolein / acrylic acid production ratio was placed in a second zone closest to the outlet.

[0043] A reactant gas stream containing 8.1% by volume propylene and 14.4% by volume oxygen is introduced into the reactor inlet. To obtain similar conversions, the temperature within the reactor is adjusted so that the overall conversions for each run are within 2% of each other.

[0044] The first experiment is expected to produce significantly less maleic anhydride than the second experiment.

Claims

1. A reactor for producing acrolein and / or acrylic acid from propylene, the reactor comprising an inlet for propylene to enter the reactor, an outlet for reaction products to exit the reactor, and a catalyst bed disposed between the inlet and the outlet, the catalyst bed comprising a molybdenum and bismuth-based mixed oxide catalyst, the catalyst CAT closest to the inlet of the reactor 入口 is the catalyst CAT closest to the outlet of the reactor 出口 a reactor which produces a smaller amount of maleic anhydride compared to the total amount of acrolein and acrylic acid compared to the total amount of maleic anhydride.

2. CAT 入口 The ratio of maleic anhydride to the total amount of acrolein and acrylic acid for CAT 出口 2. The reactor of claim 1, wherein the ratio of maleic anhydride to the total amount of acrolein and acrylic acid for the reactor is less than the ratio for the reactor of claim 1.

3. CAT 入口 is CAT in at least one characteristic or variable selected from composition, size, preparation method, carrier, and concentration 出口 The reactor according to any one of claims 1 to 2, which is different from

4. The catalyst bed comprises a gradient composition, and the composition of the catalyst is CAT 入口 From CAT 出口 2. The reactor of claim 1, wherein the temperature is changed to

5. The catalyst bed comprises two or more zones, and the catalyst located in the first zone is CAT 入口 wherein the catalyst in the second zone is CAT 出口 10. The reactor of claim 1, comprising:

6. The catalyst bed includes three or more zones, and the catalyst in one or more zones located between the zone closest to the inlet and the zone closest to the outlet is 入口 the ratio of maleic anhydride to the total amount of acrolein and acrylic acid produced by the catalyst located in the zone closest to the reactor CAT 出口 6. The reactor of claim 5, wherein the reactor produces a ratio of maleic anhydride to the total amount of acrolein and acrylic acid that is less than the ratio of maleic anhydride to the total amount of acrolein and acrylic acid produced by the catalyst in the zone closest to the outlet of the reactor.

7. The molybdenum and bismuth-based mixed oxide catalyst comprises a compound of formula I: Mo １２ Bi ａ X ｂ Y ｃ Z ｄ O ｅ Formula I During the ceremony, X is at least one element selected from the group consisting of iron, cobalt, and nickel; Y is at least one element selected from the group consisting of magnesium, calcium, strontium, barium, manganese, copper, zinc, cerium, boron, phosphorus, arsenic, tellurium, antimony, chromium, tungsten, sodium, potassium, rubidium, and cesium; a=0.1~2.0, b=1 to 12, c=0.01 to 3, d=0 to 20; 7. The reactor of claim 1, wherein e is based on the oxidation states of other elements in the catalyst.

8. 8. The reactor of any one of claims 1 to 7, wherein the molybdenum and bismuth based mixed oxide catalyst produces a ratio of maleic anhydride to the total amount of acrolein and acrylic acid in the range of 250 to 10,000 ppm.

9. CAT 入口 produces a ratio of maleic anhydride to the total amount of acrolein and acrylic acid in the range of 250 to 5,000 ppm, and CAT 出口 9. The reactor of claim 1, wherein the ratio of maleic anhydride to the total amount of acrolein and acrylic acid is in the range of 2,000 to 10,000 ppm.

10. CAT 入口 produces a ratio of maleic anhydride to the total amount of acrolein and acrylic acid in the range of 250 to 4,000 ppm, and CAT 出口 10. The reactor of claim 9, wherein the ratio of maleic anhydride to the total amount of acrolein and acrylic acid ranges from 2,000 to 8,000.

11. 1. A method comprising: A process comprising oxidizing propylene in a reactor according to any one of claims 1 to 10, wherein the reaction products exiting the reactor comprise acrolein.

12. 12. The method of claim 11, further comprising oxidizing the acrolein to produce acrylic acid.

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