Method for producing gamma-butyrolactone from biomass

Abstract

An improved process for producing a high yield and high purity gamma-butyrolactone (GBL) product from a starting biomass containing poly-4-hydroxybutyrate (P4HB) and water is disclosed. The process includes recycling a portion of the GBL product to replace the water to obtain a substantially water-free biomass slurry that is subjected to a conversion process to convert the P4HB to GBL.

Description

[Technical field]

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 325,243, filed March 30, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to an improved process for producing gamma-butyrolactone (GBL) from biomass. [Background technology]

[0003] Due to depletion of petroleum resources, rising energy prices, and environmental concerns, the development of energy-efficient biorefinery processes to produce bio-based chemicals from renewable, low-cost carbon resources offers a unique solution to overcome the increasing constraints of petroleum-based chemicals.

[0004] One chemical with a wide range of industrial and pharmaceutical applications that can be produced using biorefinery processes is gamma-butyrolactone (GBL). The global market demand for GBL is estimated at 850 million pounds per year, with total annual sales reaching $1 billion. GBL is a colorless, weak odor liquid that is primarily used as an intermediate in the production of commercially important chemicals such as 1,4-butanediol (BDO), tetrahydrofuran (THF), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), 2-pyrrolidinone, N-vinylpyrrolidone (NVP), and polyvinylpyrrolidone (PVP). These chemicals have applications in high performance solvents for electronics, lubricant oil extraction, magnetic wire coatings, engineering resins, pharmaceutical intermediates, cosmetics, hairsprays, and high value-added polymers. GBL has many uses on its own, including as a paint stripper, a degreaser, a viscosity modifier for polyurethanes, a dispersant for water-soluble inks, a hardener for urethanes and polyamides, an etching solution for metal-coated plastics, a rubber additive, and an herbicide ingredient.

[0005] Petroleum-based GBL is produced by several different chemical processes. For example, GBL is synthesized by dehydration of gamma-hydroxybutyric acid (GHB), by reaction of acetylene with formaldehyde, or by vapor-phase hydrogenation of maleic or succinic anhydride and their esters. The latter two processes are known as the Reppe and Davie processes, respectively. The Reppe process was developed in the 1940s and was historically the first commercial route to produce 1,4-butanediol. The process starts with the reaction of acetylene with formaldehyde, followed by a series of hydrogenation steps to give BDO, which is finally dehydrogenated to produce GBL. The main drawback of this process is that the starting material is highly hazardous, generally presenting handling and environmental challenges to the manufacturer. Additionally, acetylene is a relatively expensive starting material.

[0006] The Davie process, developed in the 1990s, uses a multi-step process that begins with the reaction of molten maleic anhydride with methanol to produce monomethyl maleate. The monomethyl maleate is then converted to dimethyl maleate in the presence of an acid resin catalyst. The dimethyl maleate is converted to dimethyl succinate using catalytic vapor phase hydrogenation and then finally converted to GBL through a series of addition reactions. The final product is purified to obtain high purity GBL. Many patents describe various types of hydrogenation catalysts used to convert maleic anhydride or succinic anhydride to GBL. These include copper chromite (described in U.S. Pat. No. 3,065,243), copper chromite containing nickel (described in U.S. Pat. No. 4,006,165), and mixtures of copper oxide, zinc oxide, or aluminum oxide (described in U.S. Pat. No. 5,347,021), as well as mixtures of reduced copper oxide and reduced aluminum oxide (described in U.S. Pat. No. 6,075,153).

[0007] Even with the many available hydrogenation catalysts for the production of GBL, there are deficiencies that must be overcome, such as yield, selectivity, ease of product recovery, and cost.

[0008] U.S. Patent No. 9,084,467 discloses a method for producing a bio-based gamma-butyrolactone product comprising: a) combining genetically modified biomass with poly-4-hydroxybutyrate (P4HB) and a catalyst; and b) heating the biomass with the catalyst to convert the P4HB to the GBL product, where the catalyst is sodium carbonate or calcium hydroxide.

[0009] US Patent Publication No. 2014-0170714 discloses a process for the production and purification of bio-based GBL, including a) combining genetically modified biomass with poly-4-hydroxybutyrate (P4HB) and a catalyst, b) heating the biomass with the catalyst to convert the P4HB to a GBL product, and c) removing impurities from the GBL product to form pure GBL.

[0010] According to US Pat. No. 9,084,467 and US Pat. App. Pub. No. 2014-0170714, during or after the production (e.g., cultivation) of P4HB biomass, the biomass is combined with a catalyst under suitable conditions to aid in the conversion of the P4HB polymer to a high-purity GBL product. The catalyst (in the form of a solid or solution) and the biomass are combined, for example, by mixing, flocculation, centrifugation, or spray drying, or other suitable methods known in the art to promote the interaction of the biomass and the catalyst that promotes the efficient and specific conversion of P4HB to GBL. The biomass is first dried, for example, at a temperature between about 100° C. and about 150° C. for a period of time sufficient to reduce the moisture content of the biomass. The dried biomass is then resuspended in water and combined with a catalyst to proceed with the conversion to obtain GBL. The entire contents of US Pat. No. 9,084,467 and US Pat. App. Pub. No. 2014-0170714 are incorporated by reference.

[0011] Conventional processes for producing GBL from poly(4-hydroxybutyric acid) (P4HB), such as those in U.S. Pat. No. 9,084,467 and U.S. Patent Publication No. 2014-0170714, involve spray drying (removal of water) of biomass from fermentation broth or drying, for example, with a heated drum dryer (e.g., a heated metal surface at 300° C.), followed by pyrolysis, i.e., reaction with a catalyst to convert P4HB to GBL. Conventional drying processes for biomass are energy-intensive and inefficient. Drying is necessary because the biomass containing P4HB must be heated above 150° C. to convert P4HB to GBL. The resulting GBL is very crude, with significant amounts of N-methylpyrrolidone (NMP) and many organic compounds (furfurols and amines) that can impart color and odor to the product, necessitating workup and distillation with high reflux rates and a significant number of trays in the column. The conversion process itself can require high surface temperatures and some difficult solids handling challenges. Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, there is a need to develop new processes for producing GBL that improve product yield, purity, and cost, as well as use sustainable starting materials with more positive environmental impact. [Means for solving the problem]

[0013] One aspect of the present disclosure is directed to a process for producing a high purity, high yield, bio-based gamma-butyrolactone (GBL) product from a bio-based renewable carbon resource (starting biomass), which comprises removing water from the bio-based renewable carbon resource (starting biomass) and introducing a recycle stream of GBL to replace at least a portion of the removed water. In one aspect, a process for producing a gamma-butyrolactone (GBL) product from a starting biomass containing poly-4-hydroxybutyrate (P4HB) comprises removing water from the starting biomass by replacing the water with a recycle stream of GBL in steam or liquid form to obtain a substantially water-free biomass in suspension or solution containing P4HB dissolved or suspended in GBL, and combining the thus obtained substantially water-free biomass containing P4HB and GBL with a catalyst and heating the biomass containing P4HB with the catalyst to convert P4HB to a gamma-butyrolactone (GBL) product. Thus, the vapor or liquid GBL introduced to the biomass, particularly recycled vapor or liquid GBL, acts as a solvent for the P4HB (which extracts P4HB from the host cells in the biomass). The term "substantially free of water" or "substantially free of water" as used throughout this disclosure is intended to mean that the biomass introduced to the conversion reaction (i.e., combining with the catalyst) contains about 5% or less by weight, about 4.5% or less by weight, about 4% or less by weight, about 3.5% or less by weight, about 3% or less by weight, about 2.5% or less by weight, about 2% or less by weight, about 2.5% or less by weight, about 2% or less by weight, about 1.5% or less by weight, or about 1% or less by weight based on the weight of the biomass combined with the conversion catalyst. In some embodiments, the biomass combined with the conversion catalyst does not contain added water. In one non-limiting embodiment, the process can be carried out using a multiple effect evaporator.

[0014] A multiple-effect evaporator is a device that efficiently uses the heat of steam to evaporate water. Water is boiled in a series of vessels (columns) where each vessel is held at a lower pressure than the vessel before it. Because the boiling point of water decreases with decreasing pressure, the steam boiled in one vessel can be used to heat the next vessel; only the first vessel (highest pressure) requires an external heating source. In theory, evaporators may be constructed with any number of stages, but evaporators with more than four stages are impractical except for systems where a solution is the desired product, such as chemical recovery systems where up to seven effects are used.

[0015] The disclosed method removes water contained in the starting biomass at least once, at least twice, or at least three times and replaces it with liquid or vapor GBL acting as a solvent for P4HB to obtain a biomass suspension or solution that is combined with the conversion catalyst. The biomass suspension or solution contains P4HB (extracted from host cells in the biomass) dissolved or suspended in GBL, which replaces the water contained in the starting biomass. Starting biomass from fermentation broth generally contains about 10-30% biomass (solids) and the remainder is water. The entire process from the initial input of starting biomass to the completion of the conversion reaction is fluid without the use of additional solvents such as added water (because GBL acts as a solvent for P4HB) and does not go through a drying step. The use of liquid or vapor GBL as a solvent that is recycled back to the biomass increases the purity and yield of GBL obtained as a conversion product and increases the energy efficiency of the process.

[0016] Introducing a vapor or liquid GBL recycle stream into the biomass to obtain a substantially water-free suspension or solution of biomass that is combined with a catalyst for converting P4HB to GBL can help lower the conversion reaction temperature and reduce the amount of high boiling and foul-smelling impurities. This method significantly improves heat transfer and reduces the amount of energy used in the process by at least 50%.

[0017] The content of P4HB in the starting biomass is greater than 10% by mass of the total starting biomass. The starting biomass or bio-based renewable starting material can be a genetically modified biomass as described in U.S. Patent No. 9,084,467, the entire contents of which are incorporated herein by reference. The advantage of this bioprocess is that it uses a renewable carbon source as the feedstock material, and the genetically modified microorganism produces P4HB in very high yields without harmful toxic effects on the host cells (which may limit the efficiency of the process), and when combined with a catalyst and heated, it can produce bio-based GBL in good yield and good purity.

[0018] In some embodiments, the vapor or liquid GBL introduced to replace the water contained in the starting biomass is the entire recycled stream (liquid or vapor) GBL produced by the conversion process from P4HB. In some other embodiments, a portion of the vapor or liquid GBL introduced to replace the water contained in the starting biomass is added with GBL, and the remaining vapor or liquid GBL is the recycled stream. The added GBL can be bio-based GBL or petroleum-based GBL. The process according to the present disclosure can be a continuous process, and the added GBL is only introduced in the early stages of the process until the amount of recycled GBL in the biomass can replace substantially all of the water in the biomass, and the entire amount of GBL introduced to the biomass can be recycled GBL. It is to be noted that "added GBL" refers to GBL introduced to the biomass from a source other than recycled GBL. The present disclosure also relates to a bio-based gamma-butyrolactone (GBL) product produced by the process described herein. In certain embodiments, the amount of GBL in the produced conversion product (before post-production purification such as distillation) is 85%, greater than 85%, greater than 90%, greater than 91%, greater than 92%, greater than 93%, greater than 94%, or greater than 95% by weight. In further embodiments, a starting biomass comprising poly-4-hydroxybutyrate produced from a renewable resource suitable as a feedstock for the production of a gamma-butyrolactone product comprises poly-4-hydroxybutyrate that is greater than 10%, greater than 20%, greater than 30%, greater than 40%, or greater than 50% by weight of the biomass.

[0019] Specifically, the present disclosure relates to the following items:

[0020] Item 1. A method for producing a gamma-butyrolactone (GBL) product from a starting biomass containing water and poly-4-hydroxybutyrate (P4HB)-containing cells, comprising: (a) introducing the starting biomass into an evaporator; (b) introducing liquid or vaporous GBL into the evaporator as a solvent in an amount equal to or less than the weight of the water removed to obtain a suspension or solution of biomass substantially free of water and containing P4HB dissolved or suspended in the GBL; (c) combining a suspension or solution of the biomass substantially free of water with a conversion catalyst and heating to convert the P4HB to GBL; and (d) recovering said GBL, The liquid or vapor GBL introduced in step (b) is a part of the recovered GBL obtained in step (d), which is recycled back to the evaporator and mixed with the biomass as a solvent; A method that does not include drying.

[0021] Item 2. The method of item 1, further comprising (e) mixing, stirring, vortexing, or agitating to facilitate extraction of P4HB from the host cells into GBL.

[0022] Item 3. The method of item 1, further comprising, prior to step (c), (f) removing solids from the substantially water-free biomass suspension or solution by filtration, sedimentation, or centrifugation.

[0023] Item 4. The method according to Item 1, wherein no water is added in the steps (a), (b) and (c).

[0024] Item 5. The method of item 1, wherein the evaporator comprises a plurality of evaporators in series in fluid communication with one another, and the recycled liquid GBL is introduced into one or more of the evaporators.

[0025] Item 6. The method of item 1, wherein the evaporator comprises a first evaporator, a second evaporator, and a third evaporator, in fluid communication with each other in series in that order, and the recycled GBL is introduced into the second evaporator and / or the third evaporator.

[0026] Item 7. The method according to Item 1, wherein the step (a) is carried out at a temperature of about 60° C. to 100° C. under vacuum or atmospheric pressure.

[0027] Item 8. The method according to item 6, wherein in the first evaporator, about 20-50% of the water contained in the starting biomass is removed, in the second evaporator, about 20-45% of the water contained in the starting biomass is removed, and in the third evaporator, about 5-35% of the water contained in the starting biomass is removed, and the recycled GBL is introduced to replace the water removed from the first and second evaporators.

[0028] Item 9. The method of item 1, wherein the biomass solution or suspension substantially free of moisture has a moisture content of about 5% by weight or less, about 4% by weight or less, about 3.5% by weight or less, about 3% by weight or less, about 2.5% by weight or less, about 2% by weight or less, about 1.5% by weight or less, or about 1% by weight or less, based on the weight of the biomass solution or suspension.

[0029] Item 10. The method according to item 1, wherein the step (a) is carried out at a temperature of about 70°C to 90°C under vacuum.

[0030] Item 11. The method according to Item 1, wherein the step (a) is carried out for a period of about 5 minutes to about 2 hours.

[0031] Item 12. The method according to item 1, wherein the recovered GBL in step (d) contains less than 5% by weight of by-products.

[0032] Item 13. The method according to Item 1, wherein the conversion in step (c) is carried out in the presence of a catalyst.

[0033] Item 14. The method according to item 13, wherein the catalyst is sodium carbonate or calcium hydroxide.

[0034] Item 15. The method according to item 1, wherein the yield of the GBL product is about 85% by weight or more based on 1 g of GBL in the conversion product per 1 g of poly-4-hydroxybutyrate.

[0035] Item 16. The method of item 1, wherein the starting biomass is a genetically modified biomass from a host cell that contains a non-natural amount of P4HB.

[0036] Item 17. A bio-based gamma-butyrolactone product produced by the method of item 1.

[0037] Item 18. The bio-based gamma-butyrolactone product of item 17, wherein the gamma-butyrolactone product contains less than 5% by weight of by-products. Effect of the Invention

[0038] An improved process for producing a high yield and high purity gamma-butyrolactone (GBL) product from a starting biomass containing poly-4-hydroxybutyrate (P4HB) and water is disclosed. The process includes recycling a portion of the GBL product to replace the water to obtain a substantially water-free biomass slurry that is subjected to a conversion process to convert the P4HB to GBL. [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 is a schematic diagram of one exemplary process for producing GBL from P4HB biomass. [Diagram 2] FIG. 2 shows a 30% solution of 300 KDa P4HB in GBL (P4HB is soluble in GBL) (left side) and extraction of P4HB from biomass by GBL in a Rotovap (right side). [Diagram 3] FIG. 3 is a photograph of P4HB extracted with GBL and precipitated in water. [Figure 4] FIG. 4 is a schematic diagram of another exemplary process for producing GBL from P4HB biomass. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] This disclosure relates to a novel process in which a recycle stream of GBL is introduced into the reaction process to help lower the reaction temperature and reduce the amount of high boiling and malodorous impurities, which significantly improves heat transfer and reduces the amount of energy used in the process by at least 50% compared to existing processes involving drying of biomass.

[0041] The process according to the embodiment omits drying of the biomass (spray drying or drum drying) and therefore saves up to 50% in energy costs compared to existing processes that include drying of the biomass.

[0042] The process described herein reduces the peak temperature experienced by the biomass during the conversion reaction in which P4HB is catalytically converted to GBL under heat treatment, and reduces the amount of side reactions that produce significant amounts of N-containing compounds such as N-methylpyrrolidone (NMP). NMP is a known carcinogen and a persistent impurity that is difficult to separate from GBL because it has a BP (boiling point) delta of only 2° C. By removing N from the biomass prior to the conversion reaction, the amount of NMP impurity can be reduced.

[0043] By eliminating the biomass drying step, the process of the embodiment eliminates the need for solids handling in the manufacturing plant.

[0044] In the process according to the embodiment, the conversion product contains high yield and purity of GBL, and subsequent separation or purification steps, for example, employing distillation / condensation columns, can be performed at reduced separation power to obtain the final GBL of desired purity and / or yield, which is quite cost-effective. In some embodiments, the resulting GBL product concentrate is greater than 99% GBL without distillation. This slurry / solution may be fed to a reactor for further degradation of the remaining polymer before recovery. The process according to the embodiment is a very clean process that substantially eliminates the high temperature decomposition by-products of biomass, and can result in 99.9% pure GBL with only one distillation step.

[0045] In some aspects, genetically modified P4HB biomass from a host organism serves as a renewable source for the conversion of poly-4-hydroxybutyrate (P4HB) to GBL. In some embodiments, the source of renewable feedstock is selected from glucose, fructose, sucrose, arabinose, maltose, lactose, xylose, fatty acids, vegetable oils, and biomass-derived syngas, or a combination of two or more thereof. In some embodiments, heating the substantially water-free suspension or solution of biomass and catalyst (i.e., the conversion reaction) is performed at a temperature between about 190° C. and about 300° C. In some embodiments, the heating temperature is about 195° C. to about 285° C., about 200° C. to about 275° C., about 200° C. to about 260° C., about 200° C. to about 250° C., about 195° C. to about 265° C., about 200° C. to about 260° C., about 205° C. to about 250° C., or about 210° C. to about 240° C. In other embodiments, the heating temperature is about 190-220° C. In some embodiments, the multiple effect evaporation process reduces the moisture content of the biomass to about 15% by weight or less, about 12% by weight or less, about 10% by weight or less, about 9% by weight or less, about 8% by weight or less, about 7% by weight or less, about 6% by weight or less, or about 5% by weight or less. In the above embodiments, the substantially water-free suspension or solution of biomass and catalyst is heated for a time period of about 30 seconds to about 5 minutes, about 1 minute to about 4 minutes, about 2 minutes to about 3 minutes, about 5 minutes to about 2 hours, about 10 minutes to about 90 minutes, about 20 minutes to about 80 minutes, about 30 minutes to about 70 minutes, about 40 minutes to about 60 minutes, or about 45 minutes to about 55 minutes. In some embodiments, the gamma-butyrolactone contains less than 10%, less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, or less than 1% of undesired by-products.

[0046] In some embodiments, the catalyst for the conversion reaction is sodium carbonate or calcium hydroxide. The weight percent of the catalyst ranges from about 4% to about 50%, about 8% to about 45%, about 10% to about 40%, about 15% to about 35%, about 20% to about 30%, or about 25% to about 30% based on the total weight of the mixture of the substantially water-free biomass suspension or solution and the catalyst. In certain embodiments, the weight percent of the catalyst ranges from about 4% to about 50%, and the heating of the substantially water-free biomass suspension or solution and the catalyst is about 300° C., about 280° C., about 250° C., about 240° C., about 230° C., about 220° C., about 210° C., or about 200° C. In some embodiments, the catalyst is 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15% calcium hydroxide by weight and the heating is at a temperature of 300°C, about 290°C, about 280°C, about 270°C, about 260°C, about 250°C, about 240°C, about 230°C, about 225°C, about 220°C, about 215°C, about 210°C, about 205°C, about 200°C, or about 195°C.

[0047] In this disclosure, P4HB includes copolymers of 4-hydroxybutyric acid and 3-hydroxybutyric acid, where the percentage of 4-hydroxybutyric acid in the copolymer is greater than 80%, greater than 82%, greater than 85%, greater than 88%, greater than 90%, greater than 92%, and preferably greater than 95%.

[0048] In some embodiments, about 0.1-30 wt% of the GBL product from the conversion reaction can be recycled back to the evaporator. In some embodiments, about 0.5-30 wt% of the GBL product, about 0.5-20 wt% of the GBL product, about 0.5-10 wt% of the GBL product, about 1-30 wt% of the GBL product, about 1-20 wt% of the GBL product, about 2-25 wt% of the GBL product, about 2-20 wt% of the GBL product, about 2-15 wt% of the GBL product, about 3-20 wt% of the GBL product, about 3-15 wt% of the GBL product, about 1-10 wt% of the GBL product, or about 2-10 wt% of the GBL product can be recycled back to the evaporator. Here, when the vapor GBL is recycled, the recycle ratio can be converted to the corresponding volume percentage.

[0049] In some embodiments, the final GBL is further processed to produce other desired commercial or specialty products, such as 1,4-butanediol (BDO), tetrahydrofuran (THF), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), 2-pyrrolidinone, N-vinylpyrrolidone (NVP), polyvinylpyrrolidone (PVP), etc.

[0050] As used herein, "biomass" or "starting biomass" contemplates any genetically modified biomass from a host (e.g., genetically modified bacteria) that contains non-naturally occurring polyhydroxyalkanoate polymers, such as poly-4-hydroxybutyrate (P4HB), as disclosed in U.S. Patent No. 9,084,467, the contents of which are incorporated herein by reference. Polyhydroxyalkanoate polymers include homopolymers of 4-hydroxybutyrate, copolymers of 4-hydroxybutyrate with other monomers, such as 3-hydroxybutyrate, or mixtures thereof.

[0051] With reference to Figure 1, an exemplary embodiment of the present disclosure includes at least a triple-effect evaporator including a first evaporator 1, a second evaporator 2, a third evaporator 3, a reaction vessel 4, a distillation column 5, a condenser 6 for recovering water vapor, and a condenser 7 for recovering GBL vapor. The first evaporator 1, the second evaporator 2, and the third evaporator 3 are in fluid communication with each other in series in that order. Although three evaporators are shown in Figure 1, the present disclosure is not so limited.

[0052] Fermentation broth (starting biomass) containing 10-50% by weight biomass (based on the total weight of the broth) containing P4HB is fed to a first evaporator 1 and heated at about 60-100°C under vacuum or at atmospheric pressure by known apparatus for an amount of time to reduce the moisture content. Water vapor is removed to a vessel such as a condenser 6. In the first evaporator, about 20-50%, about 25-45%, or about 30-40% by weight of water is removed based on the total weight of the broth.

[0053] The liquid with lower water content is transferred to a second evaporator 2 where recycled GBL stream is added to replace the water removed in the first evaporator. The second evaporator is heated at about 60-100° C. under vacuum or at atmospheric pressure by known apparatus for an amount of time to further reduce the water content. Water vapor is removed to a vessel such as a condenser 6. In the second evaporator 2, about 20-45 wt. %, about 25-40 wt. %, or about 30-35 wt. % water is further removed based on the total weight of the broth. By increasing the GBL content towards the third evaporator 3, the temperature and pressure can be adjusted to promote efficient evaporation of the remaining water.

[0054] The lower moisture content liquid biomass (i.e., a mixture of biomass, GBL, and remaining water) is transferred to a third evaporator 3, which is heated at about 60-100°C under vacuum or at atmospheric pressure by known apparatus for an amount of time to reduce the moisture content. The remaining water from the broth is removed to a vessel such as a condenser 6 to provide a slurry containing biomass including P4HB (P4HB biomass) and GBL as essential ingredients, where the biomass is substantially free of water. The slurry can be fed directly to a reactor vessel 4 for combination with a catalyst. The heating temperature of the reactor vessel is generally about 50°C-130°C, about 60°C-120°C, about 70°C-115°C, about 80°C-110°C, about 85°C-105°C, about 90°C-100°C, or about 100°C lower than conventional processes. The reactor can be a low temperature pyrolysis (LTP) unit spray pyrolysis / fluidized bed / or a normal reactor etc. Alternatively, the slurry can be preheated to 300°C and sent to the spray nozzles for LTP for flash pyrolysis. The slurry (unit liquid feed) has three times the heat transfer properties than conventional dried biomass powder obtained by spray drying and drum drying.

[0055] In other embodiments, the slurry (also referred to as a "substantially water-free biomass suspension or solution" or a "biomass suspension or solution") is optionally stirred, mixed, vortexed, or agitated to further facilitate extraction of P4HB from the host cells into GBL.

[0056] In another embodiment, as shown in FIG. 4, the slurry is optionally treated by centrifugation, settling, or filtration to remove debris before being fed into the reaction vessel 4.

[0057] As used herein, the term "substantially free of water" or "substantially free of water" is intended to mean that the biomass introduced into the conversion reaction (i.e., combining with the catalyst) contains about 5% or less, about 4.5% or less, about 4% or less, about 3.5% or less, about 3% or less, about 2.5% or less, about 2% or less, about 2.5% or less, about 2% or less, about 1.5% or less, or about 1% or less by weight, based on the weight of the biomass suspension or solution subjected to the conversion reaction. The water content of the biomass suspension or solution can be measured by known methods.

[0058] Even in FIG. 1, a recycle stream of GBL is added in the second evaporator, but the disclosure is not limited thereto. The recycle stream of GBL can be added to another evaporator, such as a third evaporator, or to one or more evaporators. Similarly, the evaporators may include one or more, two or more, three or more, etc., and the number of evaporator columns may be determined based on the amount of starting biomass, the moisture content of the starting biomass, the energy efficiency, the total cost of the process, etc.

[0059] Combining P4HB biomass substantially free of water with a catalyst According to embodiments, liquid GBL functions as a solvent such that the P4HB biomass, which is substantially free of water, is in suspension or solution such that no water is added to the conversion reaction.

[0060] In reaction vessel 4, the P4HB biomass and catalyst are combined under suitable conditions to aid in the conversion of the P4HB polymer to high purity gamma-butyrolactone product. The catalyst (in the form of a solid or solution) and biomass are combined, for example, by mixing, flocculation, centrifugation, or spray drying, or other suitable methods known in the art to promote interactions between the biomass and catalyst that promote efficient and specific conversion of P4HB to gamma-butyrolactone. Under "suitable conditions" refers to conditions that promote the catalytic reaction. For example, under conditions that maximize the production of the product gamma-butyrolactone, such as in the presence of co-reagents or other materials that contribute to the efficiency of the reaction. Other suitable conditions include the absence of impurities such as metals or other materials that impede the progress of the reaction.

[0061] As used herein, a "catalyst" refers to a substance that initiates or promotes a chemical reaction without itself being affected or consumed in the reaction. Useful catalysts include metal catalysts. In some embodiments, the catalyst lowers the onset temperature of pyrolysis and increases the rate of pyrolysis at a certain pyrolysis temperature (e.g., about 190°C to about 300°C).

[0062] In some embodiments, the catalyst is a compound containing a metal ion, such as a chloride, oxide, hydroxide, nitrate, phosphate, sulfonate, carbonate, or stearate. Suitable examples of metal ions include aluminum, antimony, barium, bismuth, cadmium, calcium, cerium, chromium, cobalt, copper, gallium, iron, lanthanum, lead, lithium, magnesium, molybdenum, nickel, palladium, potassium, silver, sodium, strontium, tin, tungsten, vanadium, or zinc. In some embodiments, the catalyst is an organic catalyst that is an amine, an azide, an enol, a glycol, a quaternary ammonium salt, a phenoxide, a cyanate, a thiocyanate, a dialkylamide, or an alkylthiolate. In some embodiments, the catalyst is calcium hydroxide. In other embodiments, the catalyst is sodium carbonate. Mixtures of two or more catalysts are also included.

[0063] In certain embodiments, the amount of metal catalyst is about 0.1% to about 15%, about 1% to about 25%, or about 4% to about 50% based on the weight of metal ions relative to the weight of the substantially water-free biomass. In some embodiments, the amount of catalyst is between about 7.5% and about 12%. In other embodiments, the amount of catalyst is about 0.5%, about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 20%, about 30%, about 40%, about 50%, or amounts therebetween based on the weight of the substantially water-free biomass.

[0064] As used herein, "sufficient amount" when used in reference to a chemical reagent in a reaction refers to the amount of the reference reagent that can satisfy the requirements of the chemical reaction and the desired purity of the product.

[0065] Thermal degradation of P4HB biomass As used herein, "pyrolysis" and "thermolysis" refer to the thermal degradation (e.g., decomposition) of P4HB biomass for conversion to GBL. Generally, the thermal degradation of P4HB biomass occurs at elevated temperatures in the presence of a catalyst. For example, in certain embodiments, the heating temperature of the processes described herein is between about 190°C and about 300°C. In some embodiments, the heating temperature is about 195°C to about 275°C, about 200°C to about 260°C, about 205°C to about 250°C, or about 210°C to about 225°C. In other embodiments, the heating temperature is about 190°C to about 220°C. The heating temperature of the reaction vessel is generally about 50°C to 130°C, about 60°C to 120°C, about 70°C to 115°C, about 80°C to 110°C, about 85°C to 105°C, about 90°C to 100°C, or about 100°C lower than in conventional processes.

[0066] "Pyrolysis" refers to the thermochemical decomposition of biomass, usually at elevated temperatures for a period of time. The duration can range from a few seconds to several hours. Under certain conditions, pyrolysis occurs in the absence of oxygen or in the presence of limited amounts of oxygen, avoiding oxygenation. Processes for the pyrolysis of P4HB biomass can include direct or indirect heat transfer. "Flash pyrolysis" refers to the rapid heating of biomass at high temperatures for the rapid decomposition of P4HB biomass, e.g., depolymerization of PP4HB in the biomass. Another example of flash pyrolysis is RTP. TM Rapid pyrolysis (RTP) from Envergent Technologies, Des Plaines, Illinois. TM Techniques and equipment convert the feedstock into bio-oil.

[0067] In some embodiments, the heating is performed under vacuum, atmospheric or controlled pressure, hi some embodiments, the heating is performed without or with reduced use of petroleum as a source of energy.

[0068] In some embodiments, the P4HB biomass / catalyst mixture is heated for a time sufficient to efficiently and specifically convert the P4HB biomass to GBL, hi some embodiments, the heating time is from about 30 seconds to about 1 minute, from about 30 seconds to about 1.5 minutes, from about 1 minute to about 10 minutes, from about 1 minute to about 5 minutes, or, for example, about 1 minute, about 2 minutes, about 1.5 minutes, about 2.5 minutes, about 3.5 minutes.

[0069] In other embodiments, the time is from about 1 minute to about 2 minutes. In still other embodiments, the heating duration is between about 5 minutes and about 30 minutes, between about 30 minutes and about 2 hours, between about 2 hours and about 10 hours, or greater than 10 hours (e.g., 24 hours).

[0070] In some embodiments, the heating temperature is, for example, about 195°C, about 200°C, about 205°C, about 210°C, about 215°C, about 220°C, about 225°C, about 230°C, about 235°C, about 240°C, about 245°C, about 250°C, about 255°C, about 260°C, about 270°C, about 275°C, about 280°C, about 290°C, including temperatures between about 190°C and about 300°C. In some embodiments, the temperature is about 200°C. In some embodiments, the temperature is about 205°C, about 210°C, about 220°C, or about 230°C.

[0071] In some embodiments, the process also includes flash pyrolysis of the remaining biomass, e.g., at a temperature of 400° C. or greater, for a time sufficient to decompose at least a portion of the remaining biomass into pyrolysis liquids. In some embodiments, the flash pyrolysis is carried out at a temperature of about 400° C. to 750° C., about 450° C. to 725° C., about 475° C. to 700° C., about 500° C. to 675° C., about 525° C. to 650° C., or about 550° C. to 625° C. In some embodiments, the residence time of the remaining biomass in the flash pyrolysis is 1 second to 15 seconds, 1 second to 5 seconds, or a time sufficient to pyrolyze the biomass to produce the desired pyrolysis precuts, e.g., pyrolysis liquids.

[0072] As used herein, "pyrolysis liquid" is defined as a low viscosity fluid that typically contains sugars, aldehydes, furans, ketones, alcohols, carboxylic acids, and lignin. This material, also known as bio-oil, is produced by pyrolysis, typically the rapid pyrolysis of biomass at a temperature sufficient to decompose at least a portion of the biomass into recoverable gases and liquids that may solidify over time. In some embodiments, the temperature sufficient to decompose the biomass is between about 400°C and 800°C, between about 450°C and 750°C, between about 500°C and 700°C, or between about 550°C and 650°C.

[0073] In certain embodiments, "recovering" gamma-butyrolactone vapors includes condensing the vapors. As used herein, the term "recovering" as applied to vapors means separating from the P4HB biomass material, including, but not limited to, recovering by, for example, condensation, separation methods such as the use of membranes, gas (e.g., vapor) phase separation such as distillation, etc. Thus, recovery may be accomplished via a condensation mechanism in which monomer component vapors are collected and condensed into liquid form and separated from the biomass material.

[0074] As a non-limiting example, the condensation of GBL vapors may be described as follows: The incoming gas / vapor stream from pyrolysis vessel 4 enters distillation column 5 where the gas / vapor stream may be pre-cooled. The gas / vapor stream then passes through a chiller where the temperature of the gas / vapor stream is reduced to the temperature required to condense the designated vapor from the gas by indirect contact with a refrigerant. The gas and condensed vapors flow from the chiller to condenser 7 where the condensed vapors are collected at the bottom. A portion of the vapor from distillation column 5 or liquid from condenser 7 is recycled back to the evaporator as a recycled GBL stream. The gas flows from the condenser free of vapor and exits the unit. The collected liquid flows out of the bottom of the condenser for storage or is pumped. For some products, the condensed vapors are solidified and the solids are collected.

[0075] In some embodiments, catalyst recovery is further included in the process of the present disclosure. For example, with calcium catalysts, calcination is a useful recovery technique. Calcination is a heat treatment process performed on minerals, metals, or ores to transform the material through decarbonation, dehydration, volatilization of organic matter, phase transformation, or oxidation. The process is usually carried out in a reactor such as a hearth furnace, shaft furnace, rotary furnace, or more recently, a fluidized bed reactor. The calcination temperature is selected to be below the melting point of the substrate but above the decomposition or phase transformation temperature. This is often taken as the temperature at which the Gibbs energy of the reaction is zero. CaCO 3 For the decomposition of CaO from CaO, the calcination temperature at ΔG=0 is calculated to be -850°C. Typically, for many minerals, the calcination temperature is in the range of about 800-1000°C or about 850-950°C, but heating in the range of 200-800°C can also be called calcination.

[0076] To recover the calcium catalyst from the biomass after recovering the GBL, the depleted biomass residue from pyrolysis is transferred directly to a calcination reactor where the biomass residue is heated in air at 825-850°C and continued for a period of time in an attempt to remove all traces of organic biomass. After the organic biomass has been removed, the catalyst can be used as is or can be purified by further separating the metal oxides present (from the fermentation medium and catalyst) based on density using equipment known to those skilled in the art.

[0077] In certain embodiments, the process may be selective to produce gamma-butyrolactone product along with less undesired by-products (e.g., dimer product of GBL (3-(dihydro-2(3H)-furanylidene)dihydro-2(3H)-furanone), other oligomers of GBL, or other by-products). For example, by employing the use of a sufficient amount of a particular catalyst, the production of undesired by-products may be reduced and the yield of GBL may be increased by at least about 2-fold. In some embodiments, the production of undesired by-products may be reduced by at least about 50%, at least about 40%, at least about 30%, at least about 20%, at least about 10%, or at least about 5%. In certain embodiments, the undesired by-products may be less than about 5% of the recovered GBL, less than about 4% of the recovered GBL, less than about 3% of the recovered GBL, less than about 2% of the recovered GBL, or less than about 1% of the recovered GBL.

[0078] The processes described herein can provide a yield of GBL expressed as a percentage yield, for example, when grown from glucose as a carbon source, the yield is up to 99%, up to 98%, up to 97%, up to 96%, or up to 95% (reported as a percentage) based on the GBL per gram recovered per gram P4HB contained in the biomass feed to the process. In other embodiments, the yield is in the range of between about 60% and about 95%, e.g., between about 65% and about 90%, or between about 70% and 90%. In other embodiments, the yield is about 98%, about 95%, about 92%, about 90%, about 88%, about 85%, about 80%, or about 75%.

[0079] As used herein, "gamma-butyrolactone" or "GBL" refers to a compound having the following chemical structure:

[0080] [ka]

[0081] The term "gamma-butyrolactone product" or "GBL" refers to a product that contains at least about 80% to 100% gamma-butyrolactone by weight. For example, in some embodiments, the gamma-butyrolactone product may contain 95% gamma-butyrolactone and 5% by weight by-products. In some embodiments, the amount of gamma-butyrolactone in the gamma-butyrolactone product is about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% by weight. In certain embodiments, the weight percent of gamma-butyrolactone produced by the processes described herein is 85%, greater than 85%, greater than 90%, or greater than 95%.

[0082] In other embodiments, the gamma-butyrolactone product may be further purified, if necessary, by additional methods known in the art, such as by distillation, reactive distillation (e.g., the gamma-butyrolactone product may first be acidified to oxidize certain components (e.g., for ease of separation) and then distilled), by treatment with activated carbon for removal of colorants and / or odorants, by ion exchange treatment, by liquid-liquid extraction with a GBL-immiscible solvent (e.g., a non-polar solvent such as cyclopentane or hexane) for purification after GBL recovery to remove fatty acids, etc., by vacuum distillation, extractive distillation, or similar methods that result in further purification of the gamma-butyrolactone product and increased yield of gamma-butyrolactone. Combinations of these treatments may also be utilized. In particular, the gamma-butyrolactone product may be further purified by the methods described in U.S. Patent Application Publication No. 2014 / 0170714, the contents of which are incorporated herein by reference.

[0083] In certain embodiments, GBL is further chemically modified and / or substituted to other four carbon products (4C products) and derivatives including, but not limited to, succinic acid, 1,4-butanediamide, succinonitrile, succinamide, N-vinyl-2-pyrrolidone (NVP), 2-pyrrolidone (2-Py), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), and 1,4-butanediol (BDO). Methods and reactions for the production of these derivatives from gamma-butyrolactone are readily known to those skilled in the art.

[0084] We have demonstrated in the lab that a 30%@300,000Daltons solution of P4HB was extracted by draining and the presence of P4HB in solution was confirmed by slamming the solution against water to produce a white polymer mass as shown in Figures 2 and 3. The left test tube in Figure 2 shows a 30% solution of 300,000Dalton P4HB in GBL. The right test tube in Figure 2 shows the extraction of P4HB from biomass with GBL in a Rotovap. Figure 3 shows P4HB extracted with GBL and precipitated in water.

[0085] Another example of this process is shown in Figure 4. As shown in Figure 1, in addition to evaporators 1, 2 and 3, reaction vessel 4, distillation column 5, condenser 6 and condenser 7, a filter 8 or a centrifuge 9 is provided between the third evaporator 3 and reaction vessel 4. Similar steps described for the process shown in Figure 1 are incorporated herein by reference. The filter 8 or the centrifuge 9 can be appropriately selected by one skilled in the art.

[0086] Aspects of the invention Working Example The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0087] Example 1. Production of starting biomass from genetically engineered microorganisms producing poly-4-hydroxybutyrate (P4HB) Biomass containing poly-4-hydroxybutyrate (poly-4HB) was produced in a 20 L New Brunswick Scientific fermentor (BioFlo4500) using a genetically engineered strain specialized for high yield production of poly-4HB from glucose syrup as a carbon source. Examples of E. coli strains, fermentation conditions, media, and feeding conditions are described in U.S. Patent Nos. 6,316,262, 6,689,589, 7,081,357, and 7,229,804, the contents of which are incorporated herein by reference. This E. coli strain produced a fermentation broth with a PHA titer of approximately 100-120 g per kg broth. After cultivation, the broth was washed with deionized (DI) water by adding an equal volume of water, mixing for 2 minutes, centrifuging, and decanting the water. The washed broth contained approximately 10% by weight P4HB, 10% by weight biomass and salts, and 80% by weight water based on the total weight of the broth.

[0088] Example 2. Production of gamma-butyrolactone (GBL) from starting biomass Next, 1000 g of the washed broth obtained in Example 1 was sent to a first evaporator and heated at 100° C. for 30 minutes to remove about 40% water based on the total weight of the broth. The resulting solution was sent to a second evaporator, which was fed with a recycled stream of GBL to replace the water removed in the first evaporator. This mixture was heated at 100° C. for 30 minutes to remove about 40% more water based on the total weight of the broth. The resulting solution was transferred to a third evaporator and heated at 100° C. for 20 minutes to remove the remaining water. The resulting slurry contained about 25% P4HB by weight, about 25% biomass and salts by weight, about 47% GBL by weight, and less than 3% water by weight based on the total weight of the slurry.

[0089] The slurry (substantially water-free biomass solution / suspension) was optionally filtered to further refine the GBL product, resulting in a polymer solution containing about 30 wt. % P4HB, about 3 wt. % biomass and salts, and about 66 wt. % GBL, based on the total weight of the polymer solution.

[0090] The resulting filtered, virtually water-free biomass solution was diluted with lime (98% Ca(OH) 2 Mixed with standard hydrated limestone (Mississippi Lime Co.) GLB+P4HB+Ca(OH) 2 The pyrolysis of was carried out in a stirred flask at 200-250°C under vortex or stirring. At the start of the process, the inside of the flask contained GLB+P4HB+Ca(OH). 2 A weighed sample of GLB+P4HB+Ca(OH) was added and a nitrogen purge flow was established. Stirring and heating were then started. Once the flask temperature reached its set point (e.g., approximately 204°C), the nitrogen purge allowed the GLB+P4HB+Ca(OH) 2 Gases evolved in the sample were swept out of the flask and into a series of glass condensers or cold traps. The condenser consisted of a chilled glass upright condenser tower with a condensate collecting bulb at the base. A glycol / water mixture held at 0°C was circulated through all the glass condensers. The chilled gases leaving the top of the first condenser were directed downwards through a second condenser and a second condensate collecting bulb before being vented into a glass impinger filled with deionized water.

[0091] The total pyrolysis run time was approximately 60 minutes.

[0092] After the pyrolysis run was completed, the condensate from the condenser was collected and weighed. The results showed that the weight of the combined condensate was approximately 240 g. Analysis of the condensate by Karl Fisher moisture analysis and GC-MS showed that the condensate contained 3% moisture, 0.06% fatty acids, and the remaining material was GBL product. Therefore, the yield of GBL product ((g GBL product per g starting P4HB) x 100%) was calculated to be approximately 87%. There was no detection of impurities such as GBL dimer, organic sulfur, and amide compounds present in the condensate by GC-MS, indicating that the purity of the GBL product from pyrolysis was about 99%.

[0093] Experiments were conducted to confirm that the process according to the embodiment employs recycled GBL to produce a substantially water-free biomass solution / suspension for a surprisingly effective conversion process of P4HB to GBL. Some Sigma GBL were doped with a known amount of undecane. Spray-dried P4HB biomass was added to the Sigma GBL and heated to 190° C. under reflux and held for 6 hours. Samples (GBL KS-1, KS-2, KS-3, and KS-4) were taken at reaction times 0, 30, 90, and 300 minutes and analyzed to determine the GBL to undecane ratio. Table 1 below shows that the GBL to undecane ratio (column "Ratio") and undecane level (PPM UD) decrease over time from time 0 to time 300 minutes.

[0094] Table 1: Kinetics of the GBL reaction using GBL as the carrier solvent.

[0095] [Table 1]

[0096] Example 3. Post-purification of bio-based GBL by distillation, stream stripping, and peroxide treatment This example outlines an optional process for purification of bio-based GBL liquid prepared by pyrolysis of genetically engineered microorganisms mixed with a catalyst to produce poly-4-hydroxybutyrate polymer as outlined above in Example 2. Note that this distillation purification step may not be necessary since the product from Example 2 is already very pure.

[0097] Purification of GBL is a batch process in which the "crude" GBL liquid recovered after pyrolysis is first filtered to remove solid particles (typically <1% of the total crude GBL weight) and then double distilled to remove compounds that contribute to odor and color.

[0098] Filtration of the crude GBL solution was performed at a lab scale using a Buchner fritted glass funnel connected to an Erlenmeyer flask. Approximately 1 liter of crude GBL was filtered, resulting in approximately 0.99 liters of GBL solution being recovered.

[0099] Distillation of the filtered GBL solution is carried out using a high vacuum 20 stage glass distillation column. The stages of the column are housed in a silver coated glass vacuum insulated sleeve to minimize heat loss from the column during the distillation process. Distillation is carried out under vacuum conditions using a vacuum pump equipped with a liquid nitrogen cryotrap. Typical column operating pressures during distillation are in the range of 25 in Hg. A condenser at the top of the column is used to run cooling water maintained at 10°C to aid in the fractionation of vapors. The column is also fitted with two thermocouples, one at the top to monitor the vapor temperature and one at the bottom to monitor the liquid feed temperature. At the start of the distillation, approximately 1 liter of filtered GBL solution is charged to the bottom of the column, followed by condenser cooling water and vacuum. Once the pressure has stabilized, the filtered GBL solution is slowly heated to the boiling point of GBL (204°C) using a heating mantle.

[0100] During the initial stage of distillation, the water contained in the filtered GBL is first removed and discarded together with the lower boiling impurities. When the water and lower boiling impurities are completely removed, the GBL liquid feed temperature increases to the boiling point of GBL. At this stage, most of the vapor generated at the top of the column is GBL, which is condensed, collected and stored for further distillation. When the temperature of the feed is observed to increase rapidly above 204°C, the distillation is stopped. The total amount of GBL liquid recovered in the first distillation was 0.9 liters with a purity of 97%.

[0101] In another variation of the second distillation, 1-3% (by weight of GBL) of 30% hydrogen peroxide solution was added to the pre-distilled GBL liquid along with DI water. The peroxide acts to oxidize impurities in the GBL liquid, making them less volatile and therefore easier to separate. To perform this distillation, 0.9 liters of pre-distilled GBL liquid was added to the bottom of the distillation column along with 203 g of DI water and 10.2 g of 30-32% hydrogen peroxide (Sigma-Aldrich). Condenser cooling water and vacuum were started and the GBL liquid feed was heated. The distillation produced first and second transition water fractions ahead of the pure GBL vapor. Both the first and second fractions were discarded and the pure GBL liquid was recovered. Analysis of the GBL liquid by GC-MS showed a purity of >99.5% with very low odor and color. To remove additional water, the purified GBL solution may be stored on dry molecular sieves (3-4 Å pore size, Sigma-Aldrich) until use. A portion of the GBL solution thus purified is recycled back to the evaporator of Example 2.

[0102] Table 2 below summarizes the heat balance for an existing process involving drying of the starting biomass, where most of the water from fermentation is evaporated using a spray dryer ("base case process"), compared to the process of Example 2. As can be seen from Table 1, as the recycle ratio (recirculated GBL / product GBL) increases, the required evaporator surface area decreases, and the heat from the recycled GBL can be used more efficiently for evaporation.

[0103] Table 2: Summary of energy usage by the base case process and the GBL recycle process

[0104] [Table 2]

[0105] Another variation of the above purification process is to add DI water and / or a 30% hydrogen peroxide solution during the first distillation stage. Additional purification steps may include treatment with ozone, ion exchange resins, or activated carbon.

[0106] In another embodiment, the gamma-butyrolactone produced from the processes described herein can also be subjected directly to hydrogenation, esterification, or amidation conditions to produce the corresponding diols, hydroxyl esters, and amides (e.g., H 2 When subjected to hydrogenation with alkyl esters, esterification with alkyl alcohols, and amidation with alkyl amines, they can produce 1,4-butanediol, alkyl 4-hydroxybutyrate, or N-alkyl 2-pyrrolidone, respectively.

[0107] The processing of fats and oils to produce alcohols offers some insight in this regard. Fat and oils are a significant source of fatty alcohols, which are used in a variety of applications, such as lubricants and surfactants. Fats are typically not directly hydrogenated, as the intensive reaction conditions during the hydrogenation process tend to downgrade glycerol to lower alcohols, such as propylene glycol and propanol. For this reason, it is conventional to first hydrolyze the oils, followed by pre-purification of the fatty acids, to allow for more efficient hydrogenation (see, for example, Lurgi's hydrogenation process in Bailey's Industrial Oil And Fat Products, 6th Edition, Vol. 6, edited by Feridoon Shahidi, John Wiley & Sons, Inc., 2005).

[0108] While the subject matter disclosed herein has been described in connection with what are presently considered to be example embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but rather covers various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0109] Unless expressly specified otherwise, except in the examples herein, all numerical ranges, amounts, values, and percentages in the above portions of this specification and the appended claims, such as those regarding amounts of substances, content of elements, times and temperatures of reactions, ratios of amounts, and the like, may be read as being prefaced with the word "about" even if the value, amount, or range is not explicitly stated to be "about."

[0110] Accordingly, unless otherwise indicated, the numerical parameters set forth in the foregoing specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed as the number of reported significant digits and by applying ordinary rounding techniques.

[0111] Although the numerical ranges and parameters setting forth the broad scope of the present invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains errors necessarily resulting from the standard deviation found in each underlying test measurement. Moreover, when numerical ranges are described herein, these ranges encompass (i.e., may include) the recited range endpoints. When weight percentages are used herein, the reported numerical values ​​are based on total weight.

[0112] It should also be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" is intended to include all subranges between (and including) the recited minimum of 1 and the recited maximum of 10, i.e., subranges with a minimum value of 1 or greater and a maximum value of 10 or less. As used herein, the terms "one," "a," or "an" are intended to include "at least one" or "one or more," unless otherwise specified.

Claims

1. 1. A method for producing a gamma-butyrolactone (GBL) product from a starting biomass containing water and poly-4-hydroxybutyrate (P4HB)-containing cells, comprising: (a) introducing the starting biomass into an evaporator; (b) introducing liquid or vapor GBL into the evaporator as a solvent in an amount equal to or less than the weight of the removed water to obtain a suspension or solution of biomass substantially free of water and containing P4HB dissolved or suspended in the GBL; (c) combining a suspension or solution of the biomass substantially free of water with a conversion catalyst and heating to convert the P4HB to GBL; and (d) recovering the GBL, The liquid or vapor GBL introduced in step (b) is a part of the recovered GBL obtained in step (d), which is recycled GBL that is returned to the evaporator and mixed with the biomass as a solvent; A method that does not include drying.

2. 2. The method of claim 1, further comprising step (e) mixing, stirring, vortexing, or agitating to facilitate extraction of P4HB from the host cells into GBL.

3. 2. The method of claim 1, further comprising, prior to step (c), step (f) removing solids from the substantially water-free biomass suspension or solution by filtration, sedimentation, or centrifugation.

4. 2. The method of claim 1, wherein no water is added in steps (a), (b) and (c).

5. The method of claim 1 , wherein the evaporator comprises a plurality of series evaporators in fluid communication with one another, and the recycled GBL is introduced into one or more of the evaporators.

6. 2. The method of claim 1, wherein the evaporators include a first evaporator, a second evaporator, and a third evaporator, which are in fluid communication with each other in series in that order, and the recycled GBL is introduced into the second evaporator and / or the third evaporator.

7. 2. The method of claim 1, wherein step (a) is carried out at a temperature of about 60° C. to 100° C. under vacuum or atmospheric pressure.

8. In the first evaporator, about 20 to 50% of the water contained in the starting biomass is removed, in the second evaporator, about 20 to 45% of the water contained in the starting biomass is removed, and in the third evaporator, about 5 to 35% of the water contained in the starting biomass is removed; 7. The method of claim 6, wherein the recycled GBL is introduced to replace water removed from the first and second evaporators.

9. 2. The method of claim 1, wherein the biomass solution or suspension that is substantially free of water has a moisture content of about 5% by weight or less, based on the weight of the biomass solution or suspension.

10. 10. The method of claim 1, wherein step (a) is carried out under vacuum at a temperature of about 70°C to 90°C.

11. 10. The method of claim 1, wherein step (a) is carried out for a time period of from about 5 minutes to about 2 hours.

12. 2. The method of claim 1, wherein the recovered GBL in step (d) contains less than 5% by weight of by-products.

13. 10. The method of claim 1, wherein the converting of step (c) is carried out in the presence of a catalyst.

14. 14. The method of claim 13, wherein the catalyst is sodium carbonate or calcium hydroxide.

15. 2. The method of claim 1, wherein the yield of the GBL product is about 85% by weight or greater based on grams of GBL in the conversion product per gram of P4HB.

16. 2. The method of claim 1, wherein the starting biomass is a genetically modified biomass from a host cell that contains a non-natural amount of P4HB.

17. 13. A bio-based gamma-butyrolactone product produced by the method of claim 1.

18. 20. The bio-based gamma-butyrolactone product of claim 17, wherein the gamma-butyrolactone product contains less than 5% by weight of by-products.

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