Methods and catalysts for the dehydration of sugars

Abstract

The present invention relates to a method and catalyst for sugar dehydration. In particular, the present invention relates to an aluminum salt and fulvic acid photocatalyst, a method for preparing the aluminum salt and fulvic acid photocatalyst, and a method for using the aluminum and fulvic acid photocatalyst for sugar dehydration. In one aspect, a method for preparing the photocatalyst is provided, comprising dispersing fulvic acid in a solution containing an aluminum salt to obtain the photocatalyst.

Description

[Technical field]

[0001] The present invention relates to a method and photocatalyst for sugar dehydration. In particular, the present invention relates to an aluminum and fulvic acid photocatalyst, a method for preparing the aluminum and fulvic acid photocatalyst, and a method for using the aluminum and fulvic acid photocatalyst for sugar dehydration. [Background technology]

[0002] 5-Hydroxymethylfurfural ("HMF") is an important platform chemical for producing high-value biochemicals. Converting industrial sugars such as glucose and fructose to 5-HMF is the most challenging reaction in the production of high-value biochemicals such as 2,5-furandicarboxylic acid ("FDCA"), an essential building block in the biochemical industry, and a monomer for biodegradable polymers. Sugar is a sustainable renewable resource with a lower price than petroleum and has great potential to replace fossil-based resources. Therefore, converting sugar to 5-HMF is an essential method in establishing the green chemical industry of the future.

[0003] Aluminum salts have been used as Lewis acid catalysts for sugar conversion. However, to achieve reasonable yields of 5-HMF, the thermal catalytic reaction of sugars with aluminum salts needs to proceed at relatively high temperatures. For example, high reaction temperatures (170°C) and high Bronsted acid concentrations are required to achieve good 5-HMF yields even over aluminum salt catalysts.

[0004] Additionally, high concentrations of Bronsted acids increase the cost of operations and raise potential health and safety concerns for workers.

[0005] Additionally, conducting the reaction at higher temperatures results in side reactions which produce undesirable large molecular weight by-products.

[0006] Where a prior art publication is referred to herein, it will be expressly understood that this reference does not constitute an acknowledgement that that publication forms part of the common general knowledge in the art in Australia or any other country. Summary of the Invention

[0007] Embodiments of the present invention provide aluminum salt and fulvic acid photocatalysts, methods for preparing the aluminum salt and fulvic acid photocatalysts, and methods for using the aluminum salt and fulvic acid component photocatalysts for the dehydration of sugars, aldoses and ketoses, which may at least partially address one or more of the problems or shortcomings described above, or may provide the public with a useful or commercial choice.

[0008] According to a first aspect of the present invention, there is provided a method for preparing a photocatalyst, comprising the steps of: Dispersing fulvic acid in a solution containing aluminum salts A method is provided, comprising:

[0009] According to a second aspect of the present invention, there is provided a method for preparing the photocatalyst according to the first aspect of the present invention, in which up to about 12 g / L of fulvic acid is dispersed in a solution containing about 0.005 M to about 0.02 M of an aluminum salt.

[0010] According to a third aspect of the present invention, there is provided a method for preparing a photocatalyst according to the first or second aspect, wherein the fulvic acid comprises pyrogallol or catechol.

[0011] According to a fourth aspect of the present invention there is provided a photocatalyst when produced according to the method of any one of the first, second or third aspects.

[0012] According to a fifth aspect of the present invention, A photocatalyst is provided that includes a complex of aluminum and fulvic acid, the aluminum having a concentration of about 0.005M to about 0.02M and the fulvic acid having a concentration of up to about 12 g / L.

[0013] According to a sixth aspect of the present invention, there is provided a photocatalyst according to the fifth aspect, wherein the fulvic acid comprises pyrogallol or catechol.

[0014] According to a seventh aspect of the present invention, Providing a sugar source; Combining sugar with a photocatalyst; Dehydrating sugars under light irradiation at temperatures up to about 100°C The present invention provides a use of a photocatalyst for the dehydration of sugars, comprising:

[0015] According to an eighth aspect of the present invention, Dispersing a fulvic acid and a sugar source in a solution containing an aluminum salt; Dehydrating sugars under light irradiation at temperatures up to about 100°C The present invention provides a use of a photocatalyst for the dehydration of sugars, comprising:

[0016] According to a ninth aspect of the present invention, the light irradiation is at least about 0.1 W / cm 2 The use of the photocatalyst according to the seventh or eighth aspect is provided, having an illuminance of

[0017] According to a tenth aspect of the present invention there is provided the use of a photocatalyst according to any one of the seventh, eighth or ninth aspects, wherein the light irradiation source may be visible light, ultraviolet light and / or concentrated solar light.

[0018] The use may involve one or more properties or characteristics of the photocatalyst of the fourth, fifth and sixth aspects.

[0019] Advantageously, the coordination of fulvic acid with aluminum results in strong absorption of visible light, which promotes the catalytic performance of aluminum ions as Lewis acids during the conversion of sugars to 5-hydroxymethylfurfural ("5-HMF"). Furthermore, the use of aluminum salts and fulvic acid photocatalysts results in one-pot dehydration of sugars to 5-HMF at moderate temperatures with negligible side reactions, avoiding the use of additional Bronsted acids. Advantageously, the use of fulvic acid to form the photocatalyst provides an economical source of polyphenols and phenolic ligands that impart light absorption capabilities and have the appropriate level of coordination lability with aluminum ions for effective photocatalytic conversion of sugars.

[0020] Any of the features described herein may be combined in any combination with any one or more of the other features described herein within the scope of the present invention.

[0021] The reference to any prior art in this specification is not, and should not be construed as, an acknowledgment or any form of suggestion that the prior art forms part of the common general knowledge.

[0022] Preferred features, embodiments and variations of the present invention can be identified from the following detailed description, which provides sufficient information for one skilled in the art to practice the invention. The detailed description should not be considered in any way as limiting the scope of the foregoing summary. The detailed description refers to several drawings, which are as follows: [Brief description of the drawings]

[0023] [Figure 1] 1 is a flow chart showing steps in a method for preparing a photocatalyst according to an embodiment of the present invention.

[0024] [Diagram 2] 1 is a flow chart illustrating steps in the use of a photocatalyst for the dehydration of sugars according to an embodiment of the

[0025] [Diagram 3] 1 is a series of charts showing the catalytic performance of fulvic acid-aluminum photocatalyst for the conversion of D-glucose to 5-HMF under various conditions.

[0026] [Figure 4] 1 is a chart showing the catalytic performance of photocatalysts prepared from various components of aluminum nitrate and fulvic acid for converting D-glucose to 5-HMF. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0028] The term "fulvic acid" as used herein is not intended to refer to an individual chemical compound, but instead to a family of related organic acids, phenols, polyphenols, and lignins that are soluble in water and generally have lower molecular size and weight and lower color intensity than humic acids. The term "fulvic acid" encompasses fulvic acids, fulvic acid salts ("fulverts"), and components of fulvic acids, such as polyphenols and phenols.

[0029] The term "humin" as used herein is not intended to refer to an individual chemical compound, but instead to a family of related organic acids that are insoluble in water and generally have a larger molecular size and weight and a darker color intensity than fulvic acids. The term humin encompasses humic acids and humate salts ("humates").

[0030] Furthermore, it is understood that many known methods for extracting fulvic and humic acids from organic matter may result in the extraction of both fulvic and humic acids and phenolic carboxylic acid fractions. Thus, it is recognized that the term "fulvic acid" as used herein is not intended to be construed as excluding the possible presence of humic and phenolic carboxylic acids in fractions and compositions extracted and produced by known or disclosed methods herein.

[0031] The present invention is based on the discovery that the synergistic effects of the light absorption and transport mechanisms of fulvic acid and aluminum coordination spheres with reactants can be used to efficiently convert large amounts of sugars under mild conditions to yield platform chemicals useful for industrial use. Advantageously, the use of aluminum salts and fulvic acid photocatalysis results in a one-pot dehydration of sugars to 5-hydroxymethylfurfural, avoiding the separate process of Bronsted acid catalyzed fructose dehydration to 5-HMF and improving the efficiency of the conversion.

[0032] Next, a method (100) for preparing a photocatalyst as shown in FIG. 1 will be described in detail.

[0033] In step 10, the fulvic acid can be dispersed in a solution containing an aluminum salt. However, it is also conceivable to prepare the photocatalyst using components of fulvic acid and / or humic acid.

[0034] Preferably, the type of fulvic acid is sufficient to form a coordination complex with the aluminum ions that act as light absorbing antennas. An appropriate degree of fulvic acid coordination with the aluminum ions is necessary to ensure an appropriate level of coordination lability of the sugar molecules for the photocatalytic process.

[0035] In some embodiments, the fulvic acid can be isolated or purified fulvic acid, a salt or a derivative thereof.

[0036] In other embodiments, the fulvic acid may include isolated polyphenols (e.g., pyrogallol, catechol, etc.).

[0037] In yet other embodiments, the fulvic acid may be an extract of a fulvic acid-containing material, where the fulvic acid is liberated from other organic compounds (such as insoluble humins) in the material and / or the concentration of the fulvic acid is increased relative to other components in the material.

[0038] In yet other embodiments, fulvic acid may be a naturally occurring material that has been minimally processed, such as soil, groundwater, and other environmental systems.

[0039] In some embodiments, fulvic acid may include a source of polyphenols, phenols, or amino acids. Preferably, fulvic acid may include a source of polyphenols. In this case, it is understood that polyphenols include multiple hydroxyl groups on aromatic rings. Without wishing to be bound by theory, it is assumed that the polyphenol moiety in fulvic acid coordinates with aluminum ions by a bidentate chelation mode. Surprisingly, it has been found that fulvic acid provides an economical source of ligands that have the appropriate level of coordination lability with aluminum ions for the photocatalytic conversion of sugars.

[0040] In some embodiments, the fulvic acid comprises pyrogallol or catechol.

[0041] Any suitable concentration of fulvic acid can be used. For example, the fulvic acid concentration can be up to about 12 g / L, preferably up to about 10 g / L, more preferably up to about 8 g / L. However, it is understood that the concentration of fulvic acid used can vary depending on the type and form of fulvic acid and the activity level of fulvic acid.

[0042] In some embodiments, up to about 8 g of fulvic acid can be dispersed in about 1 liter of solution containing an aluminum salt.

[0043] Any suitable aluminum salt can be used, however, in general the aluminum salt will be soluble in dimethylsulfoxide solution and the aluminum-ligand attraction should not be so strong as to prevent coordination of the sugar to the aluminum ion and thus conversion of the sugar to 5-HMF.

[0044] For example, the aluminum salt may be aluminum nitrate or aluminum chloride.

[0045] In some embodiments, the aluminum salt may be aluminum nitrate.

[0046] Any suitable concentration of aluminum salt can be used. For example, the concentration of aluminum ions in the solution can be about 0.005M to about 0.02M, preferably about 0.0075M to about 0.015M, and more preferably about 0.01M.

[0047] In some embodiments, the concentration of the aluminum salt in the solution may be about 0.01 M aluminum ion.

[0048] Typically, the ratio of fulvic acid to aluminum salt can be sufficient to promote light absorption capacity without saturating the number of ligand binding sites and reducing the number of sugar molecules that can coordinate with aluminum ions.

[0049] In some embodiments, the method of preparing the photocatalyst comprises dispersing up to about 12 g / L of fulvic acid in a solution comprising about 0.005 M to about 0.02 M of an aluminum salt. Preferably, the method comprises dispersing up to about 8 g / L of fulvic acid in a solution comprising about 0.01 M of an aluminum salt.

[0050] The solution containing the aluminum salt can preferably be continuously stirred while the fulvic acid is added to the solution.

[0051] The fulvic acid can be added to the solution containing the aluminum salt over a period of at least about 15 minutes, at least about 30 minutes, at least about 45 minutes, at least about 60 minutes, at least about 75 minutes, or at least about 90 minutes or more. However, one of ordinary skill in the art will understand that the time it takes to dissolve the fulvic acid in the solvent can vary depending on many factors, such as the source of the fulvic acid.

[0052] In some embodiments, the fulvic acid can be added to the solution under agitation until the fulvic acid is substantially dissolved in the solution.

[0053] In some embodiments, the aluminum and fulvic acid photocatalyst can be clarified.

[0054] The aluminum and fulvic acid photocatalyst can be clarified using any suitable technique known in the art. Preferably, the clarification step can be sufficient to remove or reduce suspended solids such as unreacted fulvic acid components, large organic complexes, etc.

[0055] In some embodiments, the aluminum and fulvic acid photocatalyst can be clarified using filtration methods, centrifugation, flocculation, and the like.

[0056] In some embodiments, a photocatalyst is provided when produced according to the methods of the present embodiments.

[0057] In some embodiments, A photocatalyst is provided that includes a complex of aluminum and fulvic acid, the concentration of aluminum ions being about 0.005M to about 0.02M, and the concentration of fulvic acid being up to about 12 g / L.

[0058] In use, it is envisioned that the photocatalyst of the present invention provides a mechanism for harvesting light and transferring excitation energy within a system to cost-effectively and efficiently dehydrate sugars. Advantageously, during the photocatalytic dehydration of sugars with aluminum salts and fulvic acid, any aldose sugars can be isomerized to the ketose form and then dehydrated to 5-HMF.

[0059] The method of using a photocatalyst for the dehydration of sugars (200) shown in FIG. 2 will now be described in detail.

[0060] The method of use includes one or more of the properties or characteristics of the photocatalyst described above.

[0061] A sugar source can be provided in step 210. The sugar can include monosaccharides, disaccharides, polysaccharides, or any suitable combination thereof.

[0062] In some embodiments, the sugar source may include a ketose (e.g., ribulose, xylulose, fructose, etc.) or an aldose (e.g., ribose, xylose, arabinose, glucose, galactose, lactose, maltose, sucrose, etc.) In some embodiments, the sugar source may include one or more types of sugar.

[0063] Any suitable concentration of sugar can be used, for example, about 0.05M to about 0.2M, preferably about 0.075M to about 0.15M, more preferably about 0.1M.

[0064] In some embodiments, the sugar source may contain about 0.1 M sugar.

[0065] In step 220, the sugar may be combined with a photocatalyst.

[0066] Sugar can be combined with photocatalyst using any suitable technique known in the art.Generally, the method of combining sugar with photocatalyst can be sufficient to promote the coordination of sugar with active sites in photocatalyst.However, it will be understood by those skilled in the art that the method of combining sugar with photocatalyst can vary depending on many factors, such as the type and physical properties of sugar, the type or amount of solvent and the composition of fulvic acid used, and the desired reaction conditions.

[0067] In some embodiments, a method for sugar dehydration includes combining a sugar source comprising about 0.1 M sugar with a photocatalyst comprising about 8 g / L fulvic acid and about 0.01 M aluminum salt.

[0068] In some embodiments, the fulvic acid and the sugar source can be dispersed in a solution that includes an aluminum salt. For example, it will be understood that the formation of the photocatalyst and the coordination of the sugar with the active sites in the photocatalyst can occur as a single step rather than separately.

[0069] As shown, the ratio of fulvic acid to aluminum salt can be sufficient to promote light absorption capacity without saturating the number of ligand binding sites and reducing the number of sugar molecules that can coordinate with aluminum ions.

[0070] In some embodiments, the photocatalyst comprises a complex of aluminum and fulvic acid, wherein the concentration of aluminum ions is about 0.005 M to about 0.02 M, and the concentration of fulvic acid is up to about 12 g / L. Preferably, the concentration of aluminum ions is about 0.01 M, and the concentration of fulvic acid is up to about 8 g / L.

[0071] In step 230, the sugars may be dehydrated under light irradiation at temperatures up to about 100° C. In general, the reaction conditions may be sufficient to selectively dehydrate the sugars to produce the desired products while minimizing undesirable side reactions. Advantageously, during the dehydration of sugars using aluminum salts and fulvic acid photocatalysis, any aldose sugars may be isomerized to the ketose form and then dehydrated to 5-HMF.

[0072] Sugar can be dehydrated under light irradiation for any suitable period of time.However, those skilled in the art will understand that light irradiation time can vary depending on many factors, including the type and amount of sugar, the type and ratio of fulvic acid to aluminum salt, and the type and intensity of light irradiation used.In use, it is assumed that sugar may need to be dehydrated under light irradiation for a longer period of time for the ring opening of sugar, isomerization from aldose to ketose, and / or the slow formation of fulvic acid and aluminum ion complex with sugar ligand.

[0073] For example, the sugar may be dehydrated for a period of at least about 1 hour, at least about 2 hours, at least about 4 hours, at least about 6 hours, at least about 8 hours, at least about 10 hours, at least about 12 hours, at least about 16 hours, at least about 20 hours, at least about 24 hours or more.

[0074] In some embodiments, the sugar may be dehydrated for at least about 4 hours.

[0075] The sugar may be dehydrated at any suitable temperature, for example, the sugar may be dehydrated at a temperature up to about 100°C, up to about 90°C, preferably up to about 80°C.

[0076] In some embodiments, the light irradiation can assist in heating the mixture of sugar and photocatalyst.

[0077] In other embodiments, the sugar and photocatalyst mixture may be heated by an external heat source. Advantageously, the method may proceed under near-natural conditions (e.g., using heat from a solar water heater, discontinuous irradiation, etc.) and achieve good 5-HMF yields.

[0078] The sugar may be dehydrated under light irradiation. Preferably, the sugar may be dehydrated under visible light, ultraviolet light and / or concentrated sunlight. As used herein, visible light and ultraviolet light may include light having a wavelength in the range of 300 to 750 nm.

[0079] The sugar may be dehydrated at any suitable illumination intensity. For example, the sugar may be dehydrated at an illumination intensity of at least about 0.1 W / cm 2 (approx. 1 sun), at least approx. 0.2 W / cm 2 (approx. 2 sun), at least approx. 0.4 W / cm 2 (about 4 sun), at least about 0.6 W / cm 2 (approx. 6 sun), at least approx. 0.8 W / cm 2 (approx. 8 sun), at least approx. 1.0 W / cm 2 (approx. 10 sun), at least approx. 1.5 W / cm 2 (approx. 15 sun), at least approx. 2.0 W / cm 2 (about 20 sun), at least about 2.5 W / cm 2 (approx. 25 sun), at least approx. 3.0 W / cm 2 (approx. 30 sun), at least approx. 3.5 W / cm 2 (approx. 35 sun), at least approx. 4.0 W / cm 2 (about 40 sun), at least about 4.5 W / cm 2 (approx. 45 sun), at least approx. 5.0 W / cm 2 Dehydration can be performed at an illumination intensity of about 50 suns or higher.

[0080] In some embodiments, the sugar has an electrical conductivity of about 0.1 to about 1.5 W / cm 2 The dehydration may be performed under visible light and / or ultraviolet light with an illumination intensity of (about 1 to about 15 sun).

[0081] In some embodiments, the sugar has an optical density of at least about 0.29 W / cm 2 (2.9 sun) of illuminance, it can be dehydrated under concentrated sunlight.

[0082] In use, the 5-HMF yield increases with increasing illumination intensity. Advantageously, the photocatalyst exhibits high yields under visible light irradiation, which is the main component of sunlight. For example, the highest yields were observed under light with a wavelength of about 410 nm.

[0083] The sugar and photocatalyst may be continuously stirred during dehydration of the sugar.

[0084] Photocatalytic sugar conversion can be carried out in the presence of moisture and / or air.

[0085] In use, it is hypothesized that the coordination of sugars and fulvic acid with aluminum ions forms complexes capable of absorbing visible light, promoting hydrolysis of aluminum ions and initiating proton transfer reactions, thereby facilitating the conversion of sugars to 5-HMF at moderate temperatures with negligible side reactions and without the need for the addition of a Bronsted acid. Without wishing to be bound by theory, it is believed that the coordination of fulvic acid with aluminum acts as a light absorbing antenna, resulting in strong absorption of visible light. The absorbed light may promote the catalytic performance of aluminum ions as Lewis acids during the conversion of sugars to 5-hydroxymethylfurfural, and the abundant variety of compounds in fulvic acid provide the necessary Bronsted acidity by deprotonation.

[0086] In some embodiments, the use of a photocatalyst for the dehydration of sugars further comprises extracting the dehydrated sugars to obtain 5-HMF.

[0087] The dehydrated sugars can be extracted using any suitable technique known in the art. In general, the method of extracting the dehydrated sugars can be sufficient to selectively isolate 5-HMF from unreacted sugars, undesired by-products and / or photocatalysts. Preferably, the dehydrated sugars can be extracted using solvent extraction or vacuum distillation.

[0088] In FIG. 3, a series of charts show the catalytic performance of fulvic acid-aluminum photocatalyst for the conversion of D-glucose to 5-HMF under various conditions.

[0089] Chart (A) shows the 5-HMF yields obtained at different fulvic acid concentrations under light and without light (dark). The reaction conditions were 0.01 M Al(NO3)3·9H2O, 4–16 g / L fulvic acid, 0.1 M D-glucose in 2 mL dimethyl sulfoxide, 1.2 W / cm. 2 halogen light intensity of 1000, a reaction temperature of 80° C., and 1 atm of argon.

[0090] Chart (B) shows the 5-HMF yields obtained at different reaction temperatures without light irradiation (thermocatalysis). The reaction conditions were 0.01 M Al(NO3)3·9H2O, 8 g / L fulvic acid, 0.1 M D-glucose in 2 mL dimethyl sulfoxide, 1.2 W / cm. 2 halogen light intensity of 1000 nm, a reaction time of approximately 20 hours, a reaction temperature of 90-170 °C, and 1 atm of argon.

[0091] Chart (C) shows the time course of the photocatalytic conversion over a reaction time of 20 hours. The reaction conditions were 0.01 M Al(NO3)3·9H2O, 8 g / L fulvic acid, 0.1 M D-glucose in 2 mL dimethyl sulfoxide, 1.2 W / cm 2 halogen light intensity of 1000, reaction temperature of 80°C, and 1 atm of argon.

[0092] Chart (D) shows the dependence of the photocatalytic activity of fulvic acid and aluminum photocatalyst for producing 5-HMF from D-glucose on the light intensity. The reaction conditions were 0.01 M Al(NO3)3·9H2O, 8 g / L fulvic acid, 0.1 M D-glucose in 2 mL dimethyl sulfoxide, and 0.0–0.5 W / cm. 2 halogen light intensity of about 1000 nm, a reaction time of about 20 hours, a reaction temperature of 80° C., and 1 atm of argon.

[0093] In FIG. 4, a chart shows the catalytic performance of photocatalysts prepared from various components of aluminum nitrate and fulvic acid for converting D-glucose to 5-HMF.

[0094] The reaction conditions included 0.45 W / cm2 LED light (approximately 440 nm), approximately 20 hours of reaction time, a reaction temperature of 70 °C, and 1 atm of argon. The components of fulvic acid included phenol, catechol, pyrogallol, epinephrine, trimesic acid, 2-aminoterephthalic acid, and salicylic acid.

[0095] In this specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the listed integers but do not exclude the inclusion of one or more additional integers.

[0096] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0097] By statute, the invention has been described in terms that are more or less specific to structural or organizational features. It is to be understood that the invention is not limited to the specific features shown or described, since the means described herein include preferred forms of carrying out the invention. The invention is therefore claimed in either its form or modifications within the scope of the appended claims (if any), as appropriately interpreted by those skilled in the art. EXAMPLES

[0098] The following non-limiting examples further illustrate the invention.

[0099] Example 1. Dehydration of sugar

[0100] Photocatalytic reactions using fulvic acid-aluminum photocatalyst were carried out in a photoreaction chamber. A glass tube was used as the reaction vessel. After adding D-glucose and the photocatalyst, the tube was sealed with a rubber septum cap.

[0101] The tube was placed on a magnetic stirrer, irradiated under a halogen lamp (Philips Industries: 500 W, wavelength range 400-750 nm), and stirred at a controlled reaction temperature of about 80 °C for about 20 h.

[0102] Approximately 0.29W / cm 2 A 5-HMF yield of about 43% was achieved under concentrated sunlight with a light intensity of about 1.2 W / cm (2.9 sun). 2 A 5-HMF yield of about 59% was achieved under visible light (wavelength >400 nm) with a light irradiance of about 100 nm.

[0103] Under the same reaction conditions, a 5-HMF yield of 73% was achieved by dehydration of sucrose.

[0104] Example 2. Dehydration of sugars using photocatalysts prepared using phenol or polyphenols instead of fulvic acid.

[0105] Various photocatalysts based on fulvic acid components and aluminum nitrate were prepared according to the method of the present invention. The fulvic acid components included phenol, catechol, pyrogallol, epinephrine, trimesic acid, 2-aminoterephthalic acid and salicylic acid.

[0106] The photocatalytic reaction using the photocatalyst was carried out in a photoreaction chamber. A glass tube was used as the reaction vessel. After adding D-glucose and the photocatalyst, the tube was sealed with a rubber septum cap.

[0107] The tube was placed on a magnetic stirrer, irradiated under a halogen lamp (Philips Industries: 500 W, wavelength range 400-750 nm), and stirred under an argon atmosphere at a controlled reaction temperature of about 80° C. for about 20 h.

[0108] FIG. 4 shows the catalytic performance of various photocatalysts for the conversion of D-glucose to 5-HMF.

[0109] Replacing fulvic acid with the polyphenols pyrogallol and catechol yielded 77% and 76% 5-HMF, respectively. Replacing fulvic acid with the phenol 2-aminoterephthalic acid yielded 23% 5-HMF.

[0110] Example 3. Scaled-up sugar dehydration (20 mL, light intensity 1 Wcm -2 )

[0111] The photocatalytic reaction using the photocatalyst was carried out in the photoreaction chamber. A 50 mL round-bottom flask was used as the reaction vessel. After adding D-glucose and the photocatalyst, the flask was sealed with a rubber septum cap.

[0112] The sealed flask contained 360 mg glucose, 75 mg Al(NO3)3.9H2O and 160 mg fulvic acid in 20 mL DMSO and an argon atmosphere at 1 atm above the liquid prior to the dehydration reaction. 140 mg and 180 mg fulvic acid were also tested.

[0113] The flask was placed on a magnetic stirrer and illuminated with a halogen lamp (Philips Industries: 500 W, wavelength range 400–750 nm, light intensity at the flask was 1 Wcm -2 The mixture was irradiated under a constant temperature of about 100° C. and stirred at a controlled reaction temperature of about 80° C. for about 20 hours.

[0114] Experiments using 160mg of fulvic acid yielded 71.6% 5-HMF, while changing the amount of fulvic acid to 140mg and 180mg yielded 61.5% and 67.5% 5-HMF, respectively.

[0115] Example 4. Scaled-up sugar dehydration (100 mL, light intensity 2 Wcm -2 )

[0116] The photocatalytic reaction using the photocatalyst was carried out in the photoreaction chamber. A 200 mL round-bottom flask was used as the reaction vessel. After adding D-glucose and the photocatalyst, the flask was sealed with a rubber septum cap.

[0117] The sealed flask contained 1.80 g glucose, 375 mg Al(NO3)3.9H2O and 800 mg fulvic acid in 100 mL DMSO and an argon atmosphere at 1 atm above the liquid prior to the dehydration reaction.

[0118] The flask was placed on a magnetic stirrer and illuminated with two halogen lamps (Philips Industries: 500 W, wavelength range 400–750 nm, light intensity at the flask was 2 Wcm -2 The mixture was irradiated under a constant temperature of about 100° C. and stirred at a controlled reaction temperature of about 80° C. for about 37 hours.

[0119] The reaction yielded 75.3% 5-HMF, higher than the smaller examples.

[0120] Example 5. Extent of dehydration of different sugars

[0121] Photocatalytic reactions using photocatalysts were carried out in a photoreaction chamber. Glass tubes were used as reaction vessels. After adding sugars and photocatalysts, the tubes were sealed with rubber septum caps. Three common sugars were tested: D-glucose, D-fructose, and sucrose.

[0122] The sealed tubes contained 0.1 mmol of D-glucose or sucrose, 0.1 mmol of Al(NO3)3.9H2O and 8 mg of fulvic acid in 1 mL of DMSO and an argon atmosphere at 1 atm above the liquid prior to the reaction.

[0123] The sealed tube contained 0.1 mmol of D-fructose, 0.001 mmol of Al(NO3)3.9H2O and 0.8 mg of fulvic acid in 1 mL of DMSO and an argon atmosphere at 1 atm above the liquid prior to the reaction.

[0124] The tube was placed on a magnetic stirrer and heated to 0.2 Wcm under the LED chip (410 ± 5 nm). -2 The mixture was irradiated with low light intensity at about 1000 nm and stirred at a controlled reaction temperature of about 80° C. for about 20 hours.

[0125] The 5-HMF yields from D-glucose, D-fructose and sucrose were 55%, 49% and 73%, respectively. The results are summarized in Table 1 below. [Table 1]

[0126] Reaction conditions: 0.01 mmol of Al(NO3)3·9H2O and 8 mg of fulvic acid ("FA") dissolved in 1 mL of DMSO solvent, 0.1 mmol of reactant, reaction temperature of 80 °C, reaction time of 20 h, argon atmosphere at 1 bar, light source at 0.2 W cm -2 The LED chip had a light intensity of 410±5 nm. *0.001 mmol of Al(NO3)3·9H2O and 0.8 mg of FA dissolved in 1 mL of DMSO solvent. The HMF yields are shown in parentheses in Table 1.

Claims

1. 1. A method for preparing a photocatalyst for use in dehydrating sugars, comprising the steps of: Dispersing up to about 12 g / L of fulvic acid in a solution containing about 0.005 M to about 0.02 M of aluminum salt. A method comprising:

2. 10. The method of claim 1, wherein up to about 8 g / L of fulvic acid is dispersed in a solution comprising about 0.01 M aluminum salt.

3. 3. The method of claim 1 or claim 2, wherein the fulvic acid comprises pyrogallol or catechol.

4. an aluminum and fulvic acid complex comprising about 0.005M to about 0.02M aluminum and up to about 12 g / L of fulvic acid; Photocatalyst used for sugar dehydration.

5. an aluminum and fulvic acid complex comprising about 0.01 M aluminum and up to about 8 g / L of fulvic acid; Photocatalyst used for sugar dehydration.

6. The photocatalyst according to claim 4 or claim 5, wherein the fulvic acid comprises pyrogallol or catechol.

7. Providing a sugar source; combining the sugar with a photocatalyst; dehydrating the sugar under light irradiation at a temperature of up to about 100°C; 5. Use of the photocatalyst according to claim 4 for the dehydration of sugars, comprising:

8. Dispersing a fulvic acid and a sugar source in a solution containing an aluminum salt; Dehydration of sugars under light irradiation at temperatures up to about 100°C Use of a photocatalyst for the dehydration of sugars, including

9. the sugar is provided at a concentration of about 0.1 M; The solution contains about 0.01 M aluminum and about 8 g / L fulvic acid. Use according to claim 7 or claim 8.

10. The light irradiation is at least about 0.1 W / cm ２ 9. The use according to claim 7 or claim 8, wherein the illumination intensity is

11. The light irradiation is about 0.1 W / cm ２ ~Approx. 1.5W / cm ２ 9. The use according to claim 7 or claim 8, wherein the illumination intensity is

12. 9. The use according to claim 7 or claim 8, wherein the light irradiation source is visible light, ultraviolet light and / or concentrated sunlight.

13. The use according to claim 7 or claim 8, wherein the light irradiation source has a wavelength of from about 300 nm to about 750 nm.

14. 9. The use according to claim 7 or claim 8, wherein the fulvic acid comprises pyrogallol or catechol.

15. The use according to claim 7 or claim 8, wherein dehydrating the sugar produces 5-hydroxymethylfurfural.

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