HK1236509A1 - Acrylic acid production methods - Google Patents

Abstract

The present invention relates to acrylic acid production methods. In one aspect, the present invention encompasses safe and efficient methods for providing highly pure acrylic acid. In certain embodiments, the inventive methods include the step of producing polypropiolactone from ethylene oxide at a first location, transporting the polymer to a second location and pyrolyzing the polypropiolactone to provide glacial acrylic acid. In certain embodiments, the step of pyrolyzing the polymer is performed continuously in conjunction with a polymerization process to make SAPs.

Description

Method for producing acrylic acid

The application is a divisional application of an invention patent application with application date 2013, 2 and 20, application number 201380019246.7, entitled "acrylic acid production method".

Technical Field

The present invention relates to a process for producing acrylic acid.

Background

Priority of the present application claims U.S. application No. 61/601,707 filed on day 2, 22 of 2012 and U.S. application No. 61/605,252 filed on day 3, 1 of 2012, each of which is hereby incorporated by reference in its entirety.

In recent decades, as the demand for polyacrylic acid-based superabsorbent polymers (SAPs) has increased, the production and use of Acrylic Acid (AA) has increased significantly. SAPs are widely used in the production of diapers and in agricultural applications. Successful production of SAP requires the use of high purity glacial acrylic acid. The problem arises from the fact that glacial acrylic acid is not stable in storage and transport: the material can undergo unexpectedly severe polymerization reactions. The polymerization of acrylic acid can be very vigorous, giving off considerable heat and pressure and ejecting hot vapors and polymers that can spontaneously ignite. Due to the very rapid pressure build-up, there is a risk of explosion. Several case records are known in which containers of acrylic acid explode due to vigorous ("runaway") polymerization.

Various techniques have been developed to stabilize glacial AA (see, e.g., U.S. Pat. nos. 4,480,116; 4,797,504; and 6,403,850) and most commercial AAs contain hydroquinone Monomethyl Ether (MEHQ) and dissolved oxygen for this purpose. However, the transport and storage of glacial AA remains a problem. Even if the fugitive polymerization was successfully stabilized, diacrylic acid was formed during storage. The formation of diacrylic acid cannot be prevented by chemical additives and diacrylic acid can negatively affect the properties of acrylic acid in some applications. For these reasons, many processes using acrylic acid rely on in-situ purification of glacial AA from commercial grade AA. This is an energy intensive process requiring expertise as well as complex equipment and controls, which increases the complexity and cost of the process using glacial AA as feedstock.

In addition, it has recently been discovered that the presence of large quantities of ethane-enriched shale gas in the united states and elsewhere has the potential to affect the chemical industry, and more particularly the production of acrylic acid. Almost all commercial acrylic acid is currently derived from propylene oxidation. Propylene is the major product of oil refining and its price and availability are closely related to the crude oil price. Therefore, the price of acrylic acid has increased dramatically in recent years.

Disclosure of Invention

There remains a need for a method of transporting and/or storing glacial Acrylic Acid (AA) in a safe and/or energy efficient manner. In addition, there remains a need for processes that provide alternative pathways for AA that do not rely on propylene oxidation.

In one aspect, the present invention provides a solution to the problems inherent in storing and transporting glacial acrylic acid.

In one aspect, the present invention enables the use of less expensive raw materials for acrylic acid production.

In one aspect, the present invention provides the ability to utilize less expensive raw materials at one location to meet the broader geographical need for acrylic acid and its derivatives. For example, the present invention may be deployed to utilize the C2 component of shale gas and carbon monoxide to produce the Polymer Polypropiolactone (PPL).

PPL is a stable material that can be safely transported and stored for long periods of time, with no safety concerns or quality degradation associated with shipping and storing ice AA. When glacial acrylic acid is desired, the process of the present invention provides its highly pure form by the step of depolymerizing the propiolactone when using AA. Thus, in certain embodiments the present invention enables access to acrylic acid in a safe and/or relatively inexpensive and/or highly flexible manner.

In certain embodiments, the methods of the invention comprise the steps of:

-forming polypropiolactone at a first position;

-isolating polypropiolactone;

-transporting the separated polypropiolactone to a second location;

-optionally storing polypropiolactone in stock until acrylic acid is required; and

-pyrolyzing polypropiolactone to release acrylic acid.

In certain embodiments, the present invention provides a process for producing acrylic acid, the process comprising the steps of: forming a polypropiolactone at a first position; isolating at least some of the polypropiolactone; and pyrolyzing at least some of the separated polypropiolactone at the second location to release acrylic acid. In certain embodiments, the present invention provides a process for producing acrylic acid, the process comprising the steps of: receiving at the second location the polypropiolactone formed at the first location; and pyrolyzing at least some of the received polypropiolactone at the second location to release acrylic acid.

Drawings

Fig. 1 shows a schematic diagram of certain embodiments of the present invention.

Fig. 2 illustrates exemplary first and second positions according to some embodiments of the invention.

Fig. 3 illustrates an embodiment of the present invention wherein the step of transporting the polypropiolactone to a second location includes the substeps of forming the thermoplastic propiolactone composition into a useful article that can be sold to a consumer, and collecting the useful article as a post-consumer recycle stream that can then be treated as described herein to provide acrylic acid.

FIG. 4 shows polypropylene lactone samples used to practice the invention¹H NMR spectrum.

Detailed Description

In certain embodiments, the present invention provides a process for producing acrylic acid, the process comprising the steps of: forming a polypropiolactone at a first position; isolating at least some of the polypropiolactone; and pyrolyzing at least some of the separated polypropiolactone at the second location to release acrylic acid. In certain embodiments, the method further comprises the step of transporting the separated polypropiolactone to a second location prior to pyrolyzing at least some of the separated polypropiolactone to release acrylic acid.

In certain embodiments, the present invention provides a process for producing acrylic acid, the process comprising the steps of: receiving at the second location the polypropiolactone formed at the first location; and pyrolyzing at least some of the received polypropiolactone at the second location to release acrylic acid.

In certain embodiments, the method comprises the step of storing the polypropiolactone prior to pyrolyzing at least some of the separated polypropiolactone to release acrylic acid. The step of storing the polypropiolactone may occur at the first location, the second location, one or more other locations (e.g., during transportation), or any combination of these locations. In certain embodiments, the polypropiolactone is stored at the first location prior to transport from the first location. In certain embodiments, the polypropiolactone is stored in the second location prior to pyrolyzing at least some of it. In certain embodiments, the polypropiolactone is stored for at least 1 week, at least 1 month, at least 6 months, at least 1 year, or at least 2 years.

The price difference between the different sites may make it advantageous to form polypropiolactone at one site and pyrolyze polypropiolactone at different sites to release acrylic acid. The ability to safely store and transport polypropiolactone allows polypropiolactone to be formed at a first location where raw materials are less costly than a second location, then transported to the second location and subsequently pyrolyzed to release acrylic acid.

In certain embodiments, the methods of the present invention are characterized by a location at which the polypropiolactone is produced (i.e., the first location) and a location at which at least a portion of the polypropiolactone is pyrolyzed (i.e., the second location) that is at least 100 miles away. In certain embodiments, the first location and the second location are between 100 miles and 12,000 miles away. In certain embodiments, the first location and the second location are at least 250 miles, at least 500 miles, at least 1,000 miles, at least 2,000 miles, or at least 3,000 miles away. In certain embodiments, the first location and the second location are between about 250 miles and about 1,000 miles away, between about 500 miles and about 2,000 miles away, between about 2,000 miles and about 5,000 miles away, or between about 5,000 miles and about 10,000 miles away. In certain embodiments, the first location and the second location are in different countries. In certain embodiments, the first location and the second location are on different continents.

In certain embodiments, wherein the method of the present invention comprises the step of transporting polypropiolactone from a first location to a second location, the step of transporting comprises moving the polypropiolactone a distance of more than 100 miles. In certain embodiments, the transporting step comprises moving the polypropiolactone a distance of more than 500 miles, more than 1,000 miles, more than 2,000 miles, or more than 5,000 miles. In certain embodiments, the transporting step comprises moving the polypropiolactone a distance between 100 miles and 12,000 miles. In certain embodiments, the transporting step comprises moving the polypropiolactone a distance of between about 250 miles and about 1000 miles, between about 500 miles and about 2,000 miles, between about 2,000 miles and about 5,000 miles, or between about 5,000 miles and about 10,000 miles. In certain embodiments, the transporting step comprises moving the polypropiolactone from a first country to a second country. In certain embodiments, the transporting step comprises moving the polypropiolactone from the first continent to the second continent.

In certain embodiments, the transporting step comprises moving polypropiolactone from north america to europe. In certain embodiments, the transporting step comprises moving polypropiolactone from north america to asia. In certain embodiments, the transporting step comprises moving polypropiolactone from the united states to europe. In certain embodiments, the transporting step comprises moving polypropiolactone from the united states to asia. In certain embodiments, the transporting step comprises moving polypropiolactone from the middle east to asia. In certain embodiments, the transporting step comprises moving polypropiolactone from the middle east to europe. In certain embodiments, the transporting step comprises moving polypropiolactone from saudi arabia to asia. In certain embodiments, the transporting step comprises moving polypropiolactone from saudi arabia to europe.

In certain embodiments, the transporting step comprises moving the polypropiolactone by means selected from the group consisting of truck, train, tanker, barge, ship, and any combination of any two or more of these. In certain embodiments, the method comprises the steps as described above, wherein the ethylene price at the first location is less than the ethylene price at the second location on a predetermined number of days. In certain embodiments, the method comprises the steps as described above, wherein the price of ethylene at the first location is less than the price of propylene at the second location on a predetermined number of days. In certain embodiments, the method comprises the steps as described above, wherein the price of the C2 component of the shale gas is less than the price of ethylene at the second location for a predetermined number of days. In certain embodiments, the method comprises the steps as described above, wherein the price of the C2 component of the shale gas in the first location is less than the price of propylene in the second location on a predetermined number of days. In certain embodiments, the method comprises the steps as described above, wherein the ethane price at the first location is less than the ethane price at the second location on a predetermined number of days. In certain embodiments, the method comprises the steps as described above, wherein the ethane price at the first location is less than the propane price at the second location on a predetermined number of days. The predetermined number of days may be any number of days between 15 days and 365 days (including 15 days and 365 days), between 15 days and 180 days (including 15 days and 180 days), between 30 days and 90 days (including 30 days and 90 days), between 30 days and 60 days (including 30 days and 60 days), or between 60 days and 90 days (including 60 days and 90 days) prior to the number of days in which the formation of polypropiolactone occurs.

Because the first location is close to ethane from the shale bed or shale basin, price differences between different locations may occur. Access may be through physical access to the shale gas or through access to a conduit that provides the shale gas. In certain embodiments, price differences between different locations arise because the first location is physically close to the shale bed or shale basin. In certain embodiments, the first location is characterized in that it is located within 600 miles, 450 miles, 300 miles, or 150 miles of the shale bed or shale basin. See, for example, the Platts World Shale Resources Map.

Those skilled in the art will recognize that even if the price fluctuates throughout a particular period (e.g., one day), such materials have a reported price (e.g., a daily price), and that is the expected price. Such prices can be found by reference to commercial sources, for example, Platts (including ethylene, propylene), ICIS (including ethylene, propylene). Those skilled in the art will likewise recognize that such materials have a reported price for an area that may be limited by geographic and/or political and/or other considerations (e.g., various countries such as china, the united states, saudi arabia or brazil or larger areas such as northwestern europe or smaller areas), and those skilled in the art will understand that for any given location, it is a suitable price for consultation.

Because of such price differences, it may be advantageous to export polypropiolactone from a first location to a party at a second location that intends to pyrolyze at least some of the polypropiolactone to release acrylic acid. Thus, in certain embodiments, the present invention provides a method comprising the steps of: forming a polypropiolactone at a first position; isolating at least some of the polypropiolactone; and dispatching at least some of the separated polypropiolactone to a second location for pyrolysis to release acrylic acid. The dispatch may take the form of any action intended to deliver the polypropiolactone ultimately for pyrolysis to acrylic acid (e.g., shipping, export, sale).

In certain embodiments, the method is characterized in that the released acrylic acid is glacial acrylic acid. In certain embodiments, the purity of the released glacial acrylic acid is suitable for direct use in the production of acrylic acid polymers such as SAP.

In certain embodiments, the polypropiolactone produced in the first step is characterized in that it is a liquid. In certain embodiments, such liquid polypropiolactone compositions have a significant amount of relatively low molecular weight oligomers. In certain embodiments, the number average molecular weight (M) of the polypropiolactone produced_N) Between about 200g/mol and about 10,000 g/mol. In certain embodiments, M of polypropiolactone produced_NLess than about 5,000g/mol, less than about 3,000g/mol, less than about 2,500g/mol, less than about 2,000g/mol, less than about 1,500g/mol, less than about 1,000g/mol, or less than about 750 g/mol. In certain embodiments, the polypropiolactone produced comprises oligomers containing from 2 to about 10 monomer units. In certain embodiments, such oligomers comprise cyclic oligomers. In certain embodiments, the cyclic oligomer contains an average of about 2 monomer units, about 3 monomer units, about 4 monomer units, about 5 monomer units, about 6 monomer units, up to about 10 monomer units, or a mixture of two or more of these materials.

In certain embodiments, the polypropiolactone produced in the first step is characterized in that it is a solid. In certain embodiments, the method includes the additional step of pelletizing the solid polypropiolactone so that it can be easily handled in bulk. In certain embodiments, the solid polypropiolactone composition comprises a significant percentage of high molecular weight polymer chains. In certain embodiments, such a polymeric polypropiolactone is characterized in that it has an M between about 10,000g/mol and about 1,000,000g/mol_N. In certain embodiments, the polymeric polypropiolactone is characterized in that it has greater than about 10,000g/mol, greater than about 20,000g/mol, greater than about 50,000g/mol, greater than about 70,000g/mol, greater than about 100,000g/mol, greater than about 150,000g/mol, greater than about 200,000g/mol, or greater than about 300,000g/molM_N。

In certain embodiments, the step of forming polypropiolactone includes the step of polymerizing Beta Propiolactone (BPL). Polymerization can be achieved by contacting BPL with a carboxylate polymerization initiator. The initiation process covalently incorporates such carboxylates into the polymer chain. In certain embodiments, the present invention provides a solution to the potentially undesirable effects of such incorporated initiators: that is, when PPL is depolymerized to provide acrylic acid, carboxylic acids corresponding to the polymerization initiator may also be released and may serve as contaminants of the produced acrylic acid. Thus, in certain embodiments, the step of polymerizing BPL comprises contacting BPL with a polymerization catalyst comprising an acrylate anion. Such polymers have the advantage that no non-acrylate materials caused by the bound initiator will contaminate the subsequent acrylic acid stream produced from the polymer.

In certain embodiments, the step of polymerizing BPL comprises contacting BPL with a polymerization catalyst comprising an anion of a non-volatile material. In certain embodiments, PPLs prepared from such non-volatile initiators are desirable because they produce few volatile by-products that can contaminate the produced acrylic acid stream. In certain embodiments, the nonvolatile initiator used in such embodiments comprises a polyacid. In certain embodiments, the polyacid comprises a polymeric material or an acid-functionalized solid. In certain embodiments, the polyacid comprises a polycarboxylic acid. In certain embodiments, the polyacid comprises a sulfonic acid. In certain embodiments, the polyacid comprises a carboxylic acid group and a sulfonic acid group.

In certain embodiments, the step of forming polypropiolactone includes the step of reacting ethylene oxide with carbon monoxide. In certain embodiments, the step of forming polypropiolactone includes the step of carbonylating ethylene oxide to provide propiolactone, which is then polymerized to provide PPL. In certain embodiments, BPL is not isolated and polymerized in situ to provide PPL.

In certain embodiments, the step of forming polypropiolactone comprises performing alternating copolymerizations of ethylene oxide and carbon dioxide.

In certain embodiments, the step of pyrolyzing polypropiolactone includes heating the PPL to a temperature greater than 100 ℃, greater than 150 ℃, greater than 175 ℃, greater than 200 ℃, or greater than about 220 ℃. In certain embodiments, the step of pyrolyzing polypropiolactone includes heating the PPL under an inert atmosphere. In certain embodiments, the step of pyrolyzing polypropiolactone includes heating PPL under reduced pressure. In certain embodiments, the step of pyrolyzing polypropiolactone includes heating the PPL in the presence of a depolymerization catalyst.

In certain embodiments, the process of the present invention comprises the additional step of separating acrylic acid from the pyrolysis step. In certain embodiments, the step of separating the acrylic acid comprises condensing the acid from the gas stream released from the pyrolysis step. In certain embodiments, the acrylic acid is not isolated, but is introduced directly into a polymerization reactor where the acrylic acid is polymerized to polyacrylic acid (e.g., by an anionic or free radical olefin polymerization process).

In certain embodiments, the step of pyrolyzing the PPL is performed continuously (e.g., in a feed reactor or other continuous flow reactor format). In certain embodiments, a continuous pyrolysis process is coupled to a continuous polymerization process to provide AA at a rate that matches the consumption rate of the reactor. In certain embodiments, this process has the advantage of not requiring the acrylic acid feed to the polymerization reactor and/or the removal of the stabilizer from the acrylic acid feed to the polymerization reactor.

In certain embodiments, the step of transporting polypropiolactone to the second location comprises the substeps of:

-forming the thermoplastic propiolactone composition into a useful article that can be sold to a consumer, and

-collecting the useful product as a post-consumer regeneration stream.

The regeneration stream may then be treated as described above to provide acrylic acid. Fig. 3 shows a schematic diagram of such an embodiment.

Thus, in certain embodiments, the present invention encompasses a method comprising the steps of:

-forming a polypropiolactone polymer;

-producing useful articles comprising polypropiolactone;

-collecting the polypropiolactone-containing article as a post-consumer regeneration stream; and

-pyrolyzing polypropiolactone to release acrylic acid.

In certain embodiments, the step of producing a useful article from polypropiolactone comprises preparing a consumer packaging article. In certain embodiments, the consumer packaging article comprises a bottle, a disposable food container, a foam article, a blister package, or the like. In certain embodiments, useful articles include films, such as agricultural films or packaging films. In certain embodiments, useful articles include molded plastic articles such as tableware, plastic toys, coolers, buckets, plastic components in consumer products such as electronic products, automotive parts, sporting goods, and the like. In certain embodiments, useful articles include any of a myriad of articles currently made from thermoplastics such as polyethylene, polypropylene, polystyrene, PVC, and the like. In certain embodiments, useful articles include fibers or fabrics.

In certain embodiments, the polypropiolactone-containing article is collected as a post-consumer regeneration stream; and the step of pyrolysing the polypropiolactone to release acrylic acid comprises one or more further sub-steps, such as separating the polypropiolactone component from the non-polypropiolactone component; chopping, grinding or melting an article comprising polypropiolactone; drying the chopped, ground or melted material; and/or treating the polypropiolactone-containing material to remove non-polypropiolactone components, such as colorants, fillers, additives, and the like, prior to the pyrolysis step.

In certain embodiments, the step of collecting the polypropiolactone-containing article as a post-consumer rejuvenation stream comprises the step of providing the article with indicia to communicate to a consumer or recycling facility that the material comprises polypropiolactone. In certain embodiments, such indicia include a digital indicator related to PPL. In certain embodiments, the marker comprises an SPI (Society of the Plastics Industry) regeneration code.

Examples

The following examples provide non-limiting technical details of certain aspects of the present invention.

Examples 1 to 3: laboratory-scale production of acrylic acid from ethylene oxide by means of polypropiolactone

In this example, one chemical sequence having utility in the methods of the invention was performed on a small laboratory scale.

Step 1: carbonylation of EO and polymerization of BPL.

A300 mL Parr high pressure reactor was charged with catalyst 1([ (TPP) Al (THF))₂][Co(CO)₄]286mg,0.3mmol) and 85mL of dry, deoxygenated THF. The reactor was heated to 45 ℃, stirred at 500rpm, and pressurized to 150psi with CO. After the reactor temperature stabilized, 13.5g EO (306mmol) was injected at 600psi CO, the reaction mixture was maintained at 600psi for 210min after EO injection, and then the CO pressure was slowly vented to ambient pressure. A solution of catalyst 2 was then added to the reactor under nitrogen (PPNTFA,1.98g 3.0mmol in 5mL dichloromethane). The mixture was stirred in the reactor at 45 ℃ for 16 hours. The polymerization was quenched by the addition of 33mL of 1% HCl in MeOH. Then 250mL of MeOH was added to precipitate the polymer. The reactor was emptied and charged with 20mL of CHCl₃And (6) washing. The collected reaction mixture and washings were combined and filtered to yield a white solid. The solid was washed with 100mL MeOH and dissolved in 40mL CHCl₃Neutralized and re-precipitated in 300mL MeOH. The precipitate was filtered, washed with 200mL MeOH and dried in a vacuum oven at 40 ℃ for 16 hours to provide 15.51g PPL. Proton NMR Spectroscopy (CDCl) of Polymer₃) Shown in fig. 4.

Step 2: pyrolysis of polypropiolactone

In a 50mL round bottom flask, 10g of sand from step 1, 2.0g of poly (propiolactone), and 8.6mg of MEHQ (hydroquinone monomethyl ether) were combined and the mixture was stirred with a magnetic stir bar. The flask was connected via a transfer adapter bridge to another 50mL round bottom flask containing 8.4mg mehq. The entire system was placed under vacuum and closed when the pressure reached 500 mtorr. The flask containing the polymer was then placed in a heating mantle and heated to 210 ℃ while the receiving flask was immersed in a dry ice/acetone bath. Acrylic acid was released from the pyrolysis of the polymer in the heated flask and vacuum transferred to the receiving flask. Heating was stopped when no additional liquid condensed in the receiving flask. At the end of pyrolysis, 1.39g of clear liquid was recovered from the receiving flask. GC analysis of the liquid showed the liquid to be acrylic acid of at least 99.4% purity.

Example 2: use of acrylates as polymerization initiators

This example was conducted under the conditions described in example 1, except that PPN acrylate was used as the polymerization catalyst. The polypropiolactone produced contains acrylate end groups and its pyrolysis releases only acrylic acid.

Example 3: storage of polypropiolactone as a stable acrylic precursor

This example was carried out under the conditions described in example 1, except that the polypropiolactone was stored in air at room temperature for 1 year prior to pyrolysis. The yield and quality of the acrylic acid produced were unchanged from example 1.

Example 4: pilot plant implementation of the acrylic acid supply chain.

In this example, the supply chain innovation of the present invention is shown on a pilot scale.

The first reactor adjacent the shale gas layer was fed with 75kg/h ethylene oxide derived from a shale gas-derived C2 product stream.the first reactor was operated at steady state conditions with 1.5M concentration of β propiolactone present in the reactor volume.in addition, catalyst 1[ (TPP) Al (THF) will contain 15mol/h₂][Co(CO)₄]The reactor is maintained at a carbon monoxide pressure of 600psig and is sized so that the feed and solvent have a residence time of at least 2.5 hours (e.g., at least 15,000L by volume). under these conditions, a reaction stream (125kg/h) is produced containing about 1740mol/h of β propiolactone.

The beta propiolactone stream relates to a separation unit that separates the gas stream into a catalyst regeneration stream comprising solvent and catalyst and a beta propiolactone stream comprising propiolactone and solvent. The catalyst regeneration stream is returned to the first reactor and the beta propiolactone stream is fed to the second reactor where it is contacted with PPN-acrylate (catalyst 2 a). The second reactor is designed as a plug flow reactor sized to maintain reactants with a residence time of at least 30 minutes (e.g., 1250L by volume) at a temperature and catalyst loading such that all of the lactone is consumed during the residence time. The second reactor produced about 1740mol/h polypropiolactone (123 kg/h). The effluent of the plug flow reactor was treated with hydrochloric acid and methanol to precipitate the polymer. The precipitated polymer is pelletized and sold as an acrylic acid precursor.

The pellets were transferred 1,500 miles by cargo ship to the acrylic end user's facility where they were stored in inventory.

The inventory is used to feed the fluidized bed reactor through a hopper. The fluidized bed reactor was purged with dry nitrogen at 150 ℃ and fed from the hopper at a rate of 500kg polypropiolactone pellets per hour. The nitrogen purged from the fluidized bed involved a condensation stage which produced a liquid glacial acrylic acid stream at a rate of about 480 kg/h.

It is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. References to details of the embodiments set forth herein are not intended to limit the scope of the claims, which in themselves recite those features regarded as essential to the invention.

Claims (10)

1. A method for producing acrylic acid, the method comprising the steps of:

forming a polypropiolactone at a first position;

isolating at least some of the polypropiolactone; and

pyrolyzing at least some of the separated polypropiolactone at the second location to release acrylic acid.

2. The method of claim 1, further comprising the step of transporting the separated polypropiolactone to the second location prior to the pyrolyzing.

3. The method of claim 2, wherein the transporting step comprises moving the polypropiolactone a distance of more than 100 miles.

4. A method for producing acrylic acid, the method comprising the steps of:

receiving at the second location the polypropiolactone formed at the first location,

and

pyrolyzing at least some of the received polypropiolactone at the second location to release acrylic acid.

5. The method of any one of claims 1 to 4, further comprising the step of storing the polypropiolactone prior to the pyrolyzing.

6. The method of any of claims 1-4, wherein the first location and the second location are between 100 miles and 12,000 miles away.

7. The method of claim 6, wherein the first location and the second location are at least 250 miles, at least 500 miles, at least 1,000 miles, at least 2,000 miles, or at least 3,000 miles away.

8. The method of claim 5, wherein the step of storing the polypropiolactone occurs at the first location.

9. The method of claim 5, wherein the step of storing the polypropiolactone occurs at the second location.

10. The method of claim 5, wherein the storing step comprises storing the polypropiolactone for at least 1 week.