阅读说明：本技术 丙烯酸的制备方法 (Method for producing acrylic acid ) 是由 D·A·埃伯特 T·A·黑尔 B·R·凯斯 J·罗斯 徐金锁 于 2019-02-21 设计创作，主要内容包括：提供了一种用于制备丙烯酸的方法,其包含：(1)通过催化气相氧化制备丙烯醛,其包含：(a)提供包含以下的反应气体：(i)5至10mol％的丙烯,(ii)0.02至0.75mol％的丙烷和(iii)0.25至1.9mol％的包含甲烷和乙烷中的至少一种的燃料混合物,其中丙烷、甲烷和乙烷的总量与丙烯的总量的摩尔比为0.01:1至0.25:1；(b)使所述反应气体与第一混合金属氧化物催化剂接触以形成包含丙烯醛的混合物,其中所述第一混合金属氧化物催化剂包含钼、铋、钴和铁中的一种或多种；和(2)使所述丙烯醛混合物与第二混合金属氧化物催化剂接触以形成包含丙烯酸的混合物,其中所述第二混合金属氧化物催化剂包含钼、钒、钨、铜和锑中的一种或多种。(Provided is a method for producing acrylic acid, comprising: (1) preparation of acrolein by catalytic gas phase oxidation, comprising: (a) providing a reaction gas comprising: (i)5 to 10 mol% propylene, (ii)0.02 to 0.75 mol% propane and (iii)0.25 to 1.9 mol% of a fuel mixture comprising at least one of methane and ethane, wherein the molar ratio of the total amount of propane, methane and ethane to the total amount of propylene is 0.01:1 to 0.25: 1; (b) contacting the reaction gas with a first mixed metal oxide catalyst to form a mixture comprising acrolein, wherein the first mixed metal oxide catalyst comprises one or more of molybdenum, bismuth, cobalt, and iron; and (2) contacting the acrolein mixture with a second mixed metal oxide catalyst to form a mixture comprising acrylic acid, wherein the second mixed metal oxide catalyst comprises one or more of molybdenum, vanadium, tungsten, copper, and antimony.)

1. A process for preparing acrylic acid comprising:

(1) preparation of acrolein by catalytic gas phase oxidation, comprising:

(a) providing a reaction gas comprising:

(i)5 to 10 mol% of propylene,

(ii)0.02 to 0.75 mol% of propane, and

(iii)0.25 to 1.9 mol% of a fuel mixture comprising at least one of methane and ethane,

wherein the molar ratio of the total amount of propane, methane, and ethane to the total amount of propylene is from 0.01:1 to 0.25: 1;

(b) contacting the reaction gas with a first mixed metal oxide catalyst to form a mixture comprising acrolein, wherein the first mixed metal oxide catalyst comprises one or more of molybdenum, bismuth, cobalt, and iron; and

(2) contacting the acrolein mixture with a second mixed metal oxide catalyst to form a mixture comprising acrylic acid, wherein the second mixed metal oxide catalyst comprises one or more of molybdenum, vanadium, tungsten, copper, and antimony.

2. The method of claim 1, wherein the fuel mixture comprises methane.

3. The process of claim 1, wherein the reaction gas comprises propylene in an amount of 7.5 to 8.2 mol%.

4. The process of claim 1, wherein the reaction gas comprises propane in an amount of 0.03 to 0.62 mol%.

5. The method of claim 1, wherein the reactant gas comprises the fuel mixture in an amount of 0.5 to 1.4 mol%.

6. The method of claim 2, wherein the reaction gas comprises methane in an amount of 1.1 to 1.4 mol%.

7. The process of claim 1, wherein the molar ratio of the total amount of propane, methane, and ethane to the total amount of propylene is from 0.1:1 to 0.18: 1.

8. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein the first mixed metal oxide catalyst comprises: a major component selected from the group consisting of molybdenum, bismuth, and combinations thereof, and a minor component selected from the group consisting of cobalt, iron, nickel, zinc, tungsten, phosphorus, manganese, potassium, magnesium, silicon, aluminum, and combinations thereof, wherein the atomic ratio of the major component to the minor component is from 9:28 to 28: 9; and is

Wherein the second mixed metal oxide catalyst comprises: a major component selected from the group consisting of molybdenum, vanadium, and combinations thereof, and a minor component selected from the group consisting of tungsten, cobalt, copper, and combinations thereof, wherein the atomic ratio of the major component to the minor component is from 1:1 to 11: 1.

9. The method of claim 1, wherein the fuel mixture comprises sulfur in an amount of less than 30 parts per million by volume of the fuel mixture.

10. A process for preparing acrylic acid comprising:

(1) preparation of acrolein by catalytic gas phase oxidation, comprising:

(a) providing a reaction gas comprising:

(i)7.5 to 8.2 mol% of propylene,

(ii)0.03 to 0.62 mol% of propane, and

(iii)0.5 to 1.4 mol% of a fuel mixture comprising at least one of methane and ethane, wherein the fuel mixture comprises sulfur in an amount of less than 30 parts per million by volume of the fuel mixture,

wherein the molar ratio of the total amount of propane, methane, and ethane to the total amount of propylene is from 0.1:1 to 0.18: 1; and

(b) contacting the reaction gas with a first mixed metal oxide catalyst to form a mixture comprising acrolein, wherein the first mixed metal oxide catalyst comprises: a major component selected from the group consisting of molybdenum, bismuth, and combinations thereof, and a minor component selected from the group consisting of cobalt, iron, nickel, zinc, tungsten, phosphorus, manganese, potassium, magnesium, silicon, aluminum, and combinations thereof, wherein the atomic ratio of the major component to the minor component is from 9:28 to 28: 9; and

(2) contacting the acrolein mixture with a second mixed metal oxide catalyst to form a mixture comprising acrylic acid, wherein the second mixed metal oxide catalyst comprises: a major component selected from the group consisting of molybdenum, vanadium, and combinations thereof, and a minor component selected from the group consisting of tungsten, cobalt, copper, and combinations thereof, wherein the atomic ratio of the major component to the minor component is from 1:1 to 11: 1.

Technical Field

The present invention relates generally to a process for the preparation of acrylic acid by catalytic gas phase oxidation. The method includes providing a reaction gas comprising a fuel mixture of propylene, propane, and at least one of methane and ethane and contacting it with a first oxidation catalyst to form an acrolein-containing mixture and contacting the acrolein mixture with a second oxidation catalyst to form an acrylic acid-containing mixture.

Background

Acrylic acid can be commercially produced by the selective oxidation of acrolein, which can be produced by the selective oxidation of propylene. Commercial propylene can be classified into different grades based on the levels of other impurities, such as refinery grade, chemical grade, and polymer grade. Depending on the price difference, it may be advantageous to use one grade over another. Although it is possible to use different grades of propylene as feed for the manufacture of acrolein by catalytic oxidation, changing the grade of propylene from one to another can have a significant effect on the fuel content of the absorber off-gas and can also be prohibitive due to the fact that acrolein plants are usually designed for fixed propylene compositions. For example, existing plants designed for chemical grade propylene (containing 3 to 7% by volume propane as the main impurity) face some challenges with high purity polymer grade propylene (containing 0.5% by volume propane as the main impurity): (1) a shortage of propane fuel (an impurity in propylene) is present, which is used as a fuel for downstream thermal oxidation of volatile organics before being discharged into the atmosphere; (2) there is a shortage of propane as ballast gas, which keeps the reactor feed composition away from the flammability zone.

Various grades of propylene have been utilized in the art as feed gases for the manufacture of acrolein. For example, WO 2014/195157 a1 discloses a process for the manufacture of acrolein from a feed gas comprising refinery grade propylene and a specific range of sulfur and unsaturated hydrocarbons. However, the prior art does not disclose a process for producing acrolein via gas phase oxidation by providing a reaction gas according to the present invention that allows high grade propylene to be used in reactor feed gas to existing equipment designed for chemical grade propylene without sacrificing productivity or requiring other capital improvements.

Therefore, there is a need to develop a process that allows the use of reactor feed gas containing high grade propylene without the disadvantages of a shortage of fuel for downstream thermal oxidation of volatile organics and a shortage of ballast gas to keep the reactor feed composition away from the flammability zone.

Disclosure of Invention

One aspect of the present invention provides a method for preparing acrylic acid, comprising: (1) preparation of acrolein by catalytic gas phase oxidation, comprising: (a) providing a reaction gas comprising: (i)5 to 10 mol% propylene, (ii)0.02 to 0.75 mol% propane and (iii)0.25 to 1.9 mol% of a fuel mixture comprising at least one of methane and ethane, wherein the molar ratio of the total amount of propane, methane and ethane to the total amount of propylene is 0.01:1 to 0.25:1, (b) contacting the reaction gas with a first mixed metal oxide catalyst to form a mixture comprising acrolein, wherein the first mixed metal oxide catalyst comprises one or more of molybdenum, bismuth, cobalt and iron; and (2) contacting the acrolein mixture with a second mixed metal oxide catalyst to form a mixture comprising acrylic acid, wherein the second mixed metal oxide catalyst comprises one or more of molybdenum, vanadium, tungsten, copper, and antimony.

Another aspect of the present invention provides a method for preparing acrylic acid, comprising: (1) preparation of acrolein by catalytic gas phase oxidation, comprising: (a) providing a reaction gas comprising: (i)7.5 to 8.2 mol% propylene, (ii)0.03 to 0.62 mol% propane and (iii)0.5 to 1.4 mol% of a fuel mixture comprising at least one of methane and ethane, wherein the fuel mixture comprises sulfur in an amount of less than 30 parts per million by volume of the fuel mixture, wherein the molar ratio of the total amount of propane, methane and ethane to the total amount of propylene is from 0.1:1 to 0.18:1, and (b) contacting a reaction gas with a first mixed metal oxide catalyst to form a mixture comprising acrolein, wherein the oxidation catalyst comprises a first mixed metal oxide catalyst comprising: a major component selected from the group consisting of molybdenum, bismuth, and combinations thereof, and a minor component selected from the group consisting of cobalt, iron, nickel, zinc, tungsten, phosphorus, manganese, potassium, magnesium, silicon, aluminum, and combinations thereof, wherein the atomic ratio of the major component to the minor component is from 9:28 to 28: 9; and (2) contacting the acrolein mixture with a second mixed metal oxide catalyst to form a mixture comprising acrylic acid, wherein the second mixed metal oxide catalyst comprises: a major component selected from the group consisting of molybdenum, vanadium, and combinations thereof, and a minor component selected from the group consisting of tungsten, cobalt, copper, and combinations thereof, wherein the atomic ratio of the major component to the minor component is from 1:1 to 11: 1.

Detailed Description

The inventors have now surprisingly found that acrylic acid can be produced from acrolein produced by catalytic gas phase oxidation of a reaction gas containing high grade propylene, while avoiding the occurrence of a shortage of fuel for downstream thermal oxidation of volatile organics and a shortage of ballast gas to keep the reactor feed composition away from flammability zones. The disadvantages are avoided by including as a supplement a fuel mixture comprising at least one of methane and ethane, thereby avoiding the effects that would otherwise result from using a high grade propylene containing relatively small amounts of propane as an impurity. Accordingly, in one aspect, the present invention provides a process for preparing acrylic acid, comprising: (1) preparing acrolein by catalytic gas phase oxidation comprising (a) providing a reaction gas comprising: (i)5 to 10 mol% propylene, (ii)0.02 to 0.75 mol% propane and (iii)0.25 to 1.9 mol% of a fuel mixture comprising at least one of methane and ethane, wherein the molar ratio of the total amount of propane, methane and ethane to the total amount of propylene is 0.01:1 to 0.25:1, (b) contacting the reaction gas with a first mixed metal oxide catalyst to form a mixture comprising acrolein, wherein the first mixed metal oxide catalyst comprises one or more of molybdenum, bismuth, cobalt and iron; and (2) contacting the acrolein mixture with a second mixed metal oxide catalyst, wherein the second mixed metal oxide catalyst comprises one or more of molybdenum, vanadium, tungsten, copper, and antimony.

The process of the invention comprises providing a reaction gas in contact with an oxidation catalyst to form a mixture comprising acrolein. The reactant gas comprises propylene, propane, and a fuel mixture comprising at least one of methane and ethane. The reaction gas contains propylene in an amount of 5 to 10 mol%, preferably 6.5 to 9 mol%, and more preferably 7.5 to 8.2 mol%, based on the total volume of the reaction gas. The reaction gas contains propane in an amount of 0.02 to 0.75 mol%, preferably 0.02 to 0.65 mol%, and more preferably 0.03 to 0.62 mol%, based on the total volume of the reaction gas. The reaction gas contains a fuel mixture comprising at least one of methane and ethane in an amount of 0.25 to 1.9 mol%, preferably 0.4 to 1.6 mol%, and more preferably 0.5 to 1.4 mol%, based on the total volume of the reaction gas. In certain embodiments, the reactant gas contains methane in an amount of 0.5 to 1.9 mol%, preferably 0.8 to 1.6 mol%, and more preferably 1.1 to 1.4 mol%, based on the total volume of the reactant gas. In certain embodiments, the molar ratio of the total amount of propane, methane, and ethane in the reaction gas to the total amount of propylene in the reaction gas is from 0.1:1 to 0.25:1, preferably from 0.1:1 to 0.2:1, and more preferably from 0.1:1 to 0.18: 1.

The reaction gas also contains an oxidant for the oxidation of propylene to acrolein and acrolein to acrylic acid. Suitable oxidizing agents include, for example, oxygen (O)₂). Suitable sources of oxygen include, for example, air or O of higher purity₂Of (2) is determined. In certain embodiments, O₂The molar ratio to propylene is 1.6:2.2, preferably 1.7: 2.0.

The reaction gas of the inventive process is contacted with an oxidation catalyst (first mixed metal oxide catalyst). Mixed metal oxide catalysts known in the art are described, for example, in U.S. patent No. 6,028,220, U.S. patent No. 8,242,376, and U.S. patent No. 9,205,414. Suitable first mixed metal oxide catalysts include, for example, catalysts comprising one or more of molybdenum, bismuth, cobalt, iron, nickel, zinc, tungsten, phosphorus, manganese, potassium, magnesium, silicon, and aluminum. In certain embodiments, the first mixed metal oxide catalyst comprises one or more of molybdenum, bismuth, cobalt, and iron. In certain embodiments, the first mixed metal oxide catalyst comprises primary and secondary components in an atomic ratio of 9:28 to 28:9, preferably 11:28 to 20:9, and more preferably 13:28 to 14: 9. In certain embodiments, the major component comprises one or more of molybdenum and bismuth. In certain embodiments, the minor component comprises one or more of cobalt, iron, nickel, zinc, tungsten, phosphorus, manganese, potassium, magnesium, silicon, and aluminum.

In certain embodiments, the fuel mixture contains methane derived from natural gas that includes impurities detrimental to the oxidation catalyst, e.g., catalyst poisons, such as various sulfur compounds (e.g., H)₂S, dimethyl sulfide, carbonyl sulfide, thiol, etc.). Gases containing such catalyst poisons are known in the art as "acid gases". Acid gases may be "desulfurized" by removing such sulfur compounds from natural gas. The presence of sulfur compounds can be removed if it adversely affects the performance of the catalyst or downstream thermal oxidizer. Suitable desulfurization techniques are known in the art and include, for example, flowing natural gas through a fixed bed packed with absorbent material. In certain embodiments, the fuel mixture contains sulfur in an amount of less than 30 parts per million, preferably less than 5 parts per million, more preferably less than 1 part per million, and even more preferably less than 0.1 parts per million, by volume of the fuel mixture.

In certain embodiments, the inventive process step of contacting the reaction gases to form the mixture comprising acrolein comprises passing the reaction gases through a reactor tube or through a plurality of reactor tubes in parallel, each reactor tube filled with the first mixed metal oxide catalyst. In certain embodiments, one or more reactor tubes contain the first mixed metal oxide catalyst up to 1 to 7 meters, preferably 2 to 6 meters, and more preferably 3 to 5 meters in length. In certain embodiments, the inner diameter of each reactor tube is in the range of 15 to 50mm, preferably 20 to 45mm, and more preferably 22 to 40 mm.

The preparation of acrylic acid further comprises contacting the acrolein mixture obtained by the above-described inventive process with a mixture of oxidation catalysts (the above-described first mixed metal oxide catalyst and second mixed metal oxide catalyst) to produce a mixture containing acrylic acid. Suitable second mixed metal oxide catalysts are known in the art, for example, as described in U.S. patent No. 4,892,856 and U.S. patent No. 6,762,148, and include, for example, one or more of molybdenum, vanadium, tungsten, copper, and antimony. In certain embodiments, the second mixed metal oxide catalyst comprises primary and secondary components in an atomic ratio of 1:1 to 11:1, preferably 2:1 to 9:1, and more preferably 3:1 to 7: 1. In certain embodiments, the major component comprises one or more of molybdenum and vanadium. In certain embodiments, the minor component comprises one or more of tungsten, copper, and antimony.

In certain embodiments, the inventive process step of contacting the reaction gas to form the mixture comprising acrolein comprises passing the reaction gas through a reactor tube or through a plurality of reactor tubes in parallel, each reactor tube filled with a mixture of the first mixed metal oxide catalyst and the second mixed metal oxide catalyst. In certain embodiments, one or more of the reactor tubes contains mixed metal oxide catalyst up to 1 to 7 meters, preferably 2 to 6 meters, and more preferably 3 to 5 meters in length. In certain embodiments, the inner diameter of each reactor tube is in the range of 15 to 50mm, preferably 20 to 45mm, and more preferably 22 to 40 mm.

Some embodiments of the invention will now be described in detail in the following examples.

Examples of the invention

Example 1

Characterization of thermal oxidation limiting conditions in exemplary and comparative processes

As shown in table 1, the conventional two-stage, single pass acrylic acid process operates under typical conditions based on chemical grade propylene ("CGP"), polymer grade propylene ("PGP"), and PGP with supplemental fuel.

TABLE 1 thermal oxidation constraints in exemplary and comparative processes

⁺"AOG" means absorber exhaust gas

The results show that the process is limited by the energy input to the thermal oxidizer. Operating under the above conditions produces a steam waste stream containing 30% to 40% of the energy input to the thermal oxidizer. As the purity of the propylene feedstock increases, the energy content of the vapor waste stream decreases. In the extreme case where the propylene content of the polymer grade propylene feed is as low as 99.5%, the energy content in the vapor waste stream is 50% in the case of CGP. If no other process modifications are made, the throughput of the plant must be reduced by 20-30% to maintain the required heat treatment conditions.

To avoid rate reduction due to energy input limitations, natural gas (or C) is used₁To C₃Fuel) was injected into the process at a molar ratio of 0.14:1 to propylene. The energy that is no longer provided by the "impurities" in the propylene is replaced by the energy produced by the low cost methane. This allows the plant to be operated with high purity feedstock while maintaining operating rates, thereby achieving reduced energy consumption for operating the thermal treatment unit and avoiding capital adjustments to the thermal treatment unit.

Example 2

Characterization of flammability limits in exemplary and comparative procedures

One hazard inherent in the oxidation of propylene is the management of the hazards associated with propylene flammability. Such hazards can be controlled by operating with the reactor feed composition outside the flammable regime from certain safety limits. The distance between the operating point and the flammability region is defined as the proximity of the flammability limit. There are certain safety margins to cover errors in flammability boundary dependencies, errors in reactor feed composition determination, and to prevent reactor tripping associated with reactor feed flow disturbances. The reactor feed is controlled so that the feed composition moves above the upper flammability limit without passing through the flammability zone. When the feed composition exceeds the flammability limit, increasing the fuel content tends to increase the oxygen required to produce a flammable mixture (more fuel increases the distance from the flammability limit). During partial oxidation of propylene, the concentration of propylene cannot be independently increased because a specific molar ratio (typically greater than 1.4:1) of oxygen to propylene is required to complete the desired chemical reaction. Due to the limitation of oxygen to propylene, when C₃As the concentration increases, the oxygen concentration must also increase. The net result of increasing the propylene concentration at a constant oxygen to propylene ratio is closer to the flammability zone. As shown in table 2, the conventional two-stage acrylic acid process with absorber off-gas recycle was operated under typical conditions.

TABLE 2 flammability limits of exemplary and comparative procedures

The results show that the process is simultaneously limited by the ability of the compressor to pump the mixed gas (air + recycle gas) to the reactor, the propylene concentration in the reactor feed and the oxygen at the reactor outlet. Each of these constraints represents an important boundary. Conversely, it is not possible to increase the capacity of the compressor without making a capital investment. Operation too close to the flammable regime may cause process disturbances, which may cause fires with a significant impact on safety and economy. If not enough excess oxygen is maintained at the reactor outlet, premature catalyst aging may result, or incomplete conversion of acrolein to acrylic acid and higher levels of acrolein fed to the thermal oxidizer. If the thermal oxidizer is unable to handle the increased acrolein loading, then insufficient oxygen may result in acrolein emissions. Therefore, the limitations are as defined above and inIn a process operated under the conditions defined above, the maximum operating rate must be reduced by 5% (based on propylene) as the propylene purity increases. By mixing C1 and C at a ratio of 0.17:1₃:C₃H₆Molar ratio by injecting natural gas into propylene, the maximum rate can be maintained at a higher propylene purity. In addition, "close to the flammability limit" is further away from the flammable region. The advantage of having an inert fuel in the reactor is again obtained.