Process for the production of 5-hydroxymethylfurfural using metal phosphates

Abstract

Methods for synthesizing 5-hydroxymethylfurfural are described. The methods include contacting a feed comprising biomass-derived cellulose or sugar monomers or oligomers or mixtures thereof with a catalyst comprising a metal phosphate. The metal phosphate can include hafnium phosphate or zirconium phosphate or combinations thereof. The catalyst has a ratio of Bronsted acid sites to Lewis acid sites greater than or equal to 0.27 and a total acid density less than or equal to 0.4.

Description

Related applications

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 18 / 890,832, filed September 20, 2024, which claims priority to U.S. Provisional Patent Application Serial No. 63 / 613,088, filed December 21, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0002] 5-Hydroxymethylfurfural (5-HMF) is a major platform chemical produced from lignocellulosic biomass, which can be converted into a universal structural unit used in a variety of green chemicals and fuels.

[0003] Monosaccharides are more expensive carbohydrates and are typically converted into HMF. Cellulose is a more abundant and cheaper carbohydrate that can be converted to produce HMF, serving as a renewable route for biofuels and fine chemicals.

[0004] HMF is commercially produced from lignocellulose, which is found in a variety of herbaceous and woody biomass sources. Lignocellulose is a structural component of plant cell walls and is a complex mixture of three main components: cellulose, hemicellulose, and lignin.

[0005] Cellulose is a linear chain of hundreds to thousands of β-linked D-glucose units. Hemicellulose is a heteropolymer found alongside cellulose in the cell walls of almost all terrestrial plants. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure and very low strength. Lignin is a polymer composed of cross-linked components of three monolignin alcohols: coumarin, coniferyl alcohol, and sinigrin. Therefore, it is a highly aromatic polymer. Different polymers exhibit varying reactivity to thermal, chemical, and biological processing.

[0006] Traditional methods for producing HMF from biomass involve hot acid digestion to hydrolyze hemicellulose to release C5 sugars, followed by catalytic isomerization and dehydration of the C5 sugars to furfural. However, due to the complex structure of lignocellulose and the acidic environment, numerous side reactions can occur. In addition to the isomerization and dehydration of C5 sugars, similar methods can isomerize the C6 sugar components of hemicellulose, or possibly even some C6 sugars derived from cellulose, to 5-HMF, which can undergo further hydrolysis to form levulinic acid and formic acid. Acetic acid is also produced from the acetyl groups on hemicellulose. Furthermore, both furfural and 5-HMF can undergo subsequent polymerization to form humin, a highly cross-linked chain of furans and hexoses.

[0007] However, commercial methods for producing HMF only yield about 50% of the theoretical value, resulting in high production costs.

[0008] Therefore, there is a need for improved and cheaper methods for preparing 5-HMF from biomass. Attached Figure Description

[0009] Figure 1 This is a diagram illustrating one implementation of a method for producing HMF from biomass.

[0010] Figure 2 This is a graph showing the variation in selectivity as zirconium phosphate is used as a catalyst to convert glucose to HMF.

[0011] Figure 3 This is a graph showing the varying selectivity of converting cellulose to HMF as hafnium phosphate and zirconium phosphate catalysts are used. Detailed Implementation

[0012] The present invention relates to a method for synthesizing 5-hydroxymethylfurfural. In some embodiments, the method includes contacting a feed comprising biomass-derived cellulose or sugar monomers or oligomers, or combinations thereof, with a catalyst comprising a metal phosphate. The catalyst has a Brønsted-Stade ratio of acid sites to Lewis acid sites greater than or equal to 0.27 and a total acid density less than or equal to 0.4.

[0013] Infrared measurements were performed by first pretreating the sample in flowing helium at 500°C for 2 hours. The sample was then cooled to room temperature to obtain the spectra. Pyridine adsorption was performed at 150°C for one hour, followed by discontinuous desorption at 150°C, 300°C, and 450°C, with spectra obtained at room temperature after each discontinuous desorption. The wavenumber was 1568 cm⁻¹. -1 Up to 1510cm -1 The substance was designated as a Brønsted acid and the wavenumber was 1473 cm⁻¹. -1 Up to 1430cm -1 The substance is designated as a Lewis acid. The area integral over this specific range is normalized to the area per milligram.

[0014] In some embodiments, the feed comprises biomass-derived cellulose. Biomass-derived cellulose may comprise natural lignocellulosic material or pretreated lignocellulosic material or microcrystalline cellulose or nanocrystalline cellulose or combinations thereof. In some embodiments, the feed comprises a mixture of biomass-derived cellulose and one or more sugar monomers and / or oligomers. In some embodiments, the feed comprises one or more sugar monomers and / or oligomers. Sugar oligomers may comprise disaccharides or oligosaccharides having between 3 and 10 sugar residues or combinations thereof. Sugar monomers are monosaccharides, including but not limited to glucose, fructose, xylose, galactose, etc., and their isomers.

[0015] In some embodiments, the metal phosphate comprises hafnium phosphate or zirconium phosphate or a combination thereof. In some embodiments, the metal phosphate has a phosphorus to metal molar ratio in the range of 0.1:1 to 10:1.

[0016] The feed can be combined with water and optional solvents. When a solvent is present, the molar ratio of solvent to water can range from 0.01:1 to 100:1. Suitable solvents include, but are not limited to, cyclic ethers, alcohols, sulfoxides, ketones, or combinations thereof. Suitable cyclic ethers include, but are not limited to, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethylfuran, or combinations thereof. Suitable alcohols include, but are not limited to, ethanol, butanol, etc. Suitable sulfoxides include, but are not limited to, dimethyl sulfoxide. Suitable ketones include, but are not limited to, methyl isobutyl ketone, γ-valerolactone, or combinations thereof.

[0017] Water may contain salt. Typically, the molar ratio of salt to water is in the range of 0.001:1 to 0.5:1. Suitable solvents include, but are not limited to, sodium chloride, lithium chloride, potassium chloride, cesium chloride, magnesium chloride, calcium chloride, or combinations thereof.

[0018] The concentration of the feed in water and solvent can be in the range of 0.01% by weight to 20% by weight.

[0019] Suitable operating conditions include, but are not limited to, temperatures ranging from 100°C to 250°C, pressures ranging from 0 MPa to 6.9 MPa, or both. Suitable contact times range from 1 second to 24 hours.

[0020] The methods may include intermittent, continuous, or semi-continuous methods.

[0021] The method can be carried out in a single reactor or multiple reactors (two or more). In some embodiments, biomass-derived cellulose can be contacted with a metal phosphate catalyst in a first reactor, resulting in the conversion of the biomass-derived cellulose into 5-hydroxymethylfurfural and sugar monomers and / or oligomers. The sugar monomers and / or oligomers generated in the first reactor can be contacted with a second catalyst in a second reactor, resulting in the conversion of the sugar monomers and / or oligomers into additional 5-hydroxymethylfurfural in the second reactor. In this arrangement, the first and second catalysts can be the same or they can be different. Any suitable catalyst can be used as the second catalyst. Suitable catalysts include, but are not limited to, metal phosphates, aluminosilicate zeolites, silicoaluminophosphate zeolites, zirconium sulfate, homogeneous acids, metal oxides, or combinations thereof.

[0022] The catalyst containing metal phosphate and the second catalyst may optionally contain a binder, such as silica or alumina, as is well known in the art.

[0023] In some embodiments, the conversion rate of biomass-derived cellulose and / or sugar monomers and / or oligomers is greater than or equal to 75%, 80%, 85%, or 90%. In some embodiments, the yield of 5-hydroxymethylfurfural is greater than or equal to 20%, 25%, 30%, 35%, or 40%. In some embodiments, the conversion rate of biomass-derived cellulose and / or sugar monomers and / or oligomers is greater than or equal to 75%, and the yield of 5-hydroxymethylfurfural is greater than or equal to 20%. In some embodiments, the conversion rate of biomass-derived cellulose and / or sugar monomers and / or oligomers is greater than or equal to 90%, and the yield of 5-hydroxymethylfurfural is greater than or equal to 30%. In some embodiments, the conversion rate of biomass-derived cellulose and / or sugar monomers and / or oligomers is greater than or equal to 90%, and the yield of 5-hydroxymethylfurfural is greater than or equal to 35%. In some embodiments, the conversion rate of biomass-derived cellulose and / or sugar monomers and / or oligomers is greater than or equal to 90%, and the yield of 5-hydroxymethylfurfural is greater than or equal to 40%.

[0024] Another aspect of the invention is a method for synthesizing 5-hydroxymethylfurfural. In one embodiment, the method includes contacting a feed comprising a biomass-derived cellulose or sugar monomer or oligomer or a mixture thereof with a catalyst in the presence of water and a solvent, wherein the catalyst comprises a metal phosphate, wherein the metal phosphate comprises hafnium phosphate or zirconium phosphate or a combination thereof, wherein the catalyst has a Brønsted-Stade ratio of acid sites to Lewis acid sites greater than or equal to 0.27 and a total acid density less than or equal to 0.4; and wherein the feed is contacted with the catalyst at a temperature in the range of 100°C to 250°C or at a pressure in the range of 0 MPa to 6.9 MPa, or for a time in the range of 1 second to 24 hours, or a combination thereof.

[0025] In some embodiments, the method includes one reactor or two (or more) reactors. A biomass-derived cellulose feed may be contacted with a first catalyst in a first reactor, where the biomass-derived cellulose is converted to 5-hydroxymethylfurfural (5-HMF) and sugar monomers and / or oligomers. The sugar monomers and / or oligomers produced in the first reactor may be contacted with a second catalyst in a second reactor, where the sugar monomers and / or oligomers are converted to additional 5-HMF. The sugar monomers contacted with the catalyst will be converted to 5-HMF, and any unconverted sugar monomers will be recycled.

[0026] The starting materials, catalysts, and reaction conditions are as described above.

[0027] Example

[0028] Example 1

[0029] Catalyst Synthesis: Two aqueous solutions were prepared. A KH₂PO₄ solution was prepared by adding 2.72 g of potassium dihydrogen phosphate (KH₂PO₄) to 50 mL of water and dissolving it under stirring. A metal chloride solution was prepared by adding 3.20 g of HfCl₄ or 2.33 g of ZrCl₄ to 50 mL of water and dissolving it under stirring. The KH₂PO₄ solution was added dropwise to the metal chloride aqueous solution under stirring. The mixture was stirred at room temperature for two hours, then aged for six hours in a Teflon-lined autoclave at 120 °C. The catalyst was recovered by filtration and thoroughly washed with water and ethanol. The catalyst was dried in air at 80 °C overnight. All catalyst samples were calcined in air at 550 °C for four hours.

[0030] Metal phosphate assay: For the conversion of cellulose or glucose, experiments were conducted in a THF / H2O solvent system (20 mL THF / H2O, 4:1 volume ratio). A mixture of microcrystalline cellulose or glucose (0.4 g), catalyst (30 wt% by weight of cellulose), and NaCl (20 wt% by weight of water) was loaded into an autoclave. The autoclave was purged three times with N2 to remove oxygen. For cellulose, the reaction mixture was heated to 190 °C for four hours; for glucose, the reaction mixture was heated to 175 °C for 2.5 hours. The product was filtered and separated into two phases.

[0031] Depending on experimental conditions, the zirconium phosphate catalyst can convert glucose with a conversion rate as high as 93% and a HMF yield of 50%. Figure 2 Depending on material variables such as the metal:P ratio, Brønsted acid:Lewis acid ratio, and the number of acid sites, metal phosphate catalysts convert cellulose to HMF in varying yields. Figure 3 The optimal HMF yield from cellulose was obtained when using a catalyst with a Brønsted acid site to Lewis acid site ratio greater than or equal to 0.27 and a total acid density less than or equal to 0.4 (Table 1).

[0032] Table 1. Catalyst Properties

[0033]

[0034] Example 2

[0035] Batch autoclave experiments were performed in a 75 mL autoclave using a salt bath. In a typical experiment, a sugar solution (0.4 g of C6 sugar in 4 g of water) was mixed with chloride (0.8 g). The aqueous solution was loaded into the autoclave, followed by tetrahydrofuran (14 g THF). A catalyst (40-60 mesh ZrO(PO4)2, 0.094 g) was added to the autoclave, which was then sealed and placed in a salt bath. After stirring for the set time (30 min in a 275 °C salt bath, with a maximum internal temperature of 212 °C), the autoclave was removed from the salt bath and placed in an ice bath. The solution was centrifuged to separate the liquid from the solid phase. The organic and aqueous phases were also decanted via pipette. Samples of both phases were submitted for LC analysis. The HMF yield was greater than 60%.

[0036] Specific implementation plan

[0037] While the following description is presented in conjunction with specific embodiments, it should be understood that the description is intended to be illustrative and not to limit the scope of the foregoing description and the appended claims.

[0038] A first embodiment of the present invention is a method for synthesizing 5-hydroxymethylfurfural, the method comprising contacting a feed comprising a biomass-derived cellulose or sugar monomer or oligomer or a mixture thereof with a catalyst comprising a metal phosphate, wherein the catalyst has a Brønsted-Stade acid site to Lewis acid site ratio greater than or equal to 0.27 and a total acid density less than or equal to 0.4. An embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment in this paragraph, wherein the metal phosphate has a phosphorus to metal molar ratio in the range of 0.11 to 101. An embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment in this paragraph, wherein the metal phosphate comprises hafnium phosphate or zirconium phosphate or a combination thereof. An embodiment of the present invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment in this paragraph, wherein contacting the feed with the catalyst comprises contacting the feed with the catalyst in the presence of water and optionally a solvent. One embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein a solvent is present, and wherein the molar ratio of the solvent to water is in the range of 0.011 to 1001. One embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein a solvent is present, and wherein the solvent comprises cyclic ethers, alcohols, sulfoxides, ketones, or combinations thereof. One embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the water contains a salt, and wherein the molar ratio of the salt to water is in the range of 0.0011 to 0.51. One embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the salt comprises sodium chloride, lithium chloride, potassium chloride, cesium chloride, magnesium chloride, calcium chloride, or combinations thereof. One embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment in this paragraph, wherein contacting the feed with the catalyst is carried out at a temperature ranging from 100°C to 250°C, or at a pressure ranging from 0 MPa to 6.9 MPa, or both. Another embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment in this paragraph, wherein contacting the feed with the catalyst includes a contact time ranging from 1 second to 24 hours.One embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein contacting the feed with the catalyst is carried out in a batch, continuous, or semi-continuous manner. Another embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein contacting the feed with a catalyst containing a metal phosphate comprises contacting biomass-derived cellulose with the catalyst containing a metal phosphate in a first reactor, wherein the biomass-derived cellulose is converted into 5-hydroxymethylfurfural and sugar monomers and / or oligomers in the first reactor; and contacting the sugar monomers and / or oligomers generated in the first reactor with a second catalyst in a second reactor, wherein the sugar monomers and / or oligomers are converted into additional 5-hydroxymethylfurfural in the second reactor. Another embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the catalyst containing the metal phosphate is different from the second catalyst. One embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the concentration of the feed in water and solvent is in the range of 0.01% by weight to 20% by weight. Another embodiment of the invention is one, any, or all of the embodiments described in the preceding embodiments to the first embodiment described in this paragraph, wherein the biomass-derived cellulose comprises natural lignocellulosic material or pretreated lignocellulosic material or microcrystalline cellulose or nanocrystalline cellulose or combinations thereof, or wherein the saccharide oligomer comprises disaccharide or oligosaccharide having between 3 and 10 sugar residues or combinations thereof; or both.

[0039] A second embodiment of the present invention is a method for synthesizing 5-hydroxymethylfurfural, the method comprising contacting a feed comprising a biomass-derived cellulose or sugar monomer or oligomer or a mixture thereof with a catalyst in the presence of water and a solvent, wherein the catalyst comprises a metal phosphate, wherein the metal phosphate comprises hafnium phosphate or zirconium phosphate or a combination thereof, wherein the catalyst has a Brønsted-Stade ratio of acid sites to Lewis acid sites greater than or equal to 0.27 and a total acid density less than or equal to 0.4; and wherein the feed is contacted with the catalyst at a temperature in the range of 100°C to 250°C, or at a pressure in the range of 0 MPa to 6.9 MPa, or for a time in the range of 1 second to 24 hours or a combination thereof. One embodiment of the invention is one, any, or all of the embodiments described in the preceding to the second embodiments of this paragraph, wherein contacting the feed with the catalyst containing a metal phosphate comprises contacting biomass-derived cellulose with the catalyst containing a metal phosphate in a first reactor, wherein the biomass-derived cellulose is converted into 5-hydroxymethylfurfural and sugar monomers and / or oligomers in the first reactor; and contacting the sugar monomers and / or oligomers generated in the first reactor with a second catalyst in a second reactor, wherein the sugar monomers and / or oligomers are converted into additional 5-hydroxymethylfurfural in the second reactor. Another embodiment of the invention is one, any, or all of the embodiments described in the preceding to the second embodiments of this paragraph, wherein the catalyst containing the metal phosphate is different from the second catalyst. One embodiment of the invention is one, any, or all of the embodiments described in the preceding to the second embodiments of this paragraph, wherein the metal phosphate has a phosphorus to metal molar ratio in the range of 0.11 to 101; or wherein the solvent to water molar ratio is in the range of 0.011 to 1001; or wherein the water contains salt, and wherein the salt to water molar ratio is in the range of 0.0011 to 0.51; or wherein the concentration of the feed in water and solvent is in the range of 0.01 wt% to 20 wt%; or a combination of the foregoing. Another embodiment of the invention is one, any, or all of the embodiments described in the preceding to the second embodiments of this paragraph, wherein a solvent is present; and wherein the solvent comprises cyclic ethers, alcohols, sulfoxides, ketones, or combinations thereof; or a combination of the foregoing.

[0040] Although no further detailed description has been provided, it is believed that those skilled in the art will be able to make full use of the invention by employing the foregoing description and will be able to readily identify the essential features of the invention without departing from its spirit and scope, and to make various changes and modifications to adapt it to various uses and situations. Therefore, the foregoing preferred embodiments should be understood as illustrative only and not as limiting the remainder of this disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0041] In the foregoing, all temperatures are expressed in degrees Celsius, and all portions and percentages are by weight unless otherwise specified.

Claims

1. A method for synthesizing 5-hydroxymethylfurfural, the method comprising: A feed comprising biomass-derived cellulose or sugar monomers or oligomers or mixtures thereof is contacted with a catalyst comprising metal phosphates, wherein the catalyst has a Brønsted acid site to Lewis acid site ratio greater than or equal to 0.27 and a total acid density less than or equal to 0.

4.

2. The method according to claim 1, wherein the metal phosphate has a phosphorus to metal molar ratio in the range of 0.1:1 to 10:

1.

3. The method according to any one of claims 1 to 2, wherein: The metal phosphate includes hafnium phosphate or zirconium phosphate or combinations thereof; or The biomass-derived cellulose includes natural lignocellulose materials, pretreated lignocellulose materials, microcrystalline cellulose, nanocrystalline cellulose, or combinations thereof; or The sugar oligomer comprises a disaccharide or an oligosaccharide having between 3 and 10 sugar residues, or a combination thereof; Or a combination of the above items.

4. The method according to any one of claims 1 to 2, wherein contacting the feed with the catalyst comprises contacting the feed with the catalyst in the presence of water and optionally a solvent.

5. The method of claim 4, wherein the solvent is present, and wherein the molar ratio of the solvent to the water is in the range of 0.01:1 to 100:1; or wherein the concentration of the feed in the water and the solvent is in the range of 0.01% by weight to 20% by weight; or both of the above.

6. The method of claim 4, wherein the solvent is present, and wherein the solvent comprises cyclic ethers, alcohols, sulfoxides, ketones, or combinations thereof.

7. The method of claim 4, wherein the water contains the salt, and wherein the molar ratio of the salt to the water is in the range of 0.001:1 to 0.5:

1.

8. The method according to any one of claims 1 to 2, wherein the contact between the feed and the catalyst is carried out at a temperature in the range of 100°C to 250°C, or at a pressure in the range of 0 MPa to 6.9 MPa, or for a time in the range of 1 second to 24 hours, or a combination thereof.

9. The method according to any one of claims 1 to 2, wherein contacting the feed with the catalyst comprising the metal phosphate comprises: The biomass-derived cellulose is contacted with the catalyst containing the metal phosphate in a first reactor, wherein the biomass-derived cellulose is converted into 5-hydroxymethylfurfural and sugar oligomers in the first reactor; as well as The sugar oligomer produced in the first reactor is contacted with a second catalyst in a second reactor, wherein the sugar oligomer is converted into additional 5-hydroxymethylfurfural in the second reactor.

10. The method of claim 9, wherein the catalyst comprising the metal phosphate is different from the second catalyst.

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