Process for converting furfural

Abstract

The furfural biomass conversion product can be converted into various useful intermediate compounds such as 5-methylfurfural, 5-methylfurfuryl alcohol, 2,5-dimethylfuran, and p-xylene. Various processes for converting the biomass conversion product 5-chloromethylfurfural to 5-methylfurfural, 5-methylfurfuryl alcohol, 2,5-dimethylfuran, and / or p-xylene are described. Various processes for converting 5-methylfurfural to 5-methylfurfuryl alcohol, 2,5-dimethylfuran, and p-xylene are also described.

Description

Technical Field

[0001] Cross - reference to related applications None

[0002] Statement regarding government support None

[0003] The present disclosure relates to the production of useful intermediate compounds from biomass conversion products, more specifically, the production of furfural, more specifically, 5 - methylfurfural, 5 - methylfurfuryl alcohol, 2,5 - dimethylfuran, and the production of p - xylene from 5 - chloromethylfurfural and / or 5 - methylfurfural.

Background Art

[0004] The shift from fossil resources to decarbonized materials creates a rich potential source of useful chemical compounds. Depending on the processes involved, by converting biomass into useful materials, by - products or waste streams containing useful chemical compounds can be generated. The challenge so far has been to develop a commercially viable process for capturing these useful chemical compounds at sufficient yields and costs.

[0005] The compound 5 - methylfurfural ( "MF") is a common by - product from biomass conversion processes, derived from biomass carbohydrates and produced directly in high yields from biomass, and includes 5 - chloromethylfurfural (CMF). CMF is a precursor to several valuable chemical substances, including MF and its alcohol, 5 - methylfurfuryl alcohol ( "MFA").

[0006] Furanaldehydes and their alcohol analogues are promising as initial platforms for a wide range of useful chemical intermediates and fuels. MFs are promising initial platforms for a wide range of useful chemical intermediates and fuels, provided they can be produced in high purity without excess reactants or undesirable by-products via commercially viable processes. One such intermediate is the heterocyclic compound 5-methylfurfuryl alcohol (MFA), a reactive furan intermediate that can be used in fine chemical synthesis. Another intermediate is the heterocyclic compound 2,5-dimethylfuran ("DMF"). DMF has an energy density about 40% higher than ethanol, making DMF an attractive biofuel. The compound is chemically stable and insoluble in water. DMF also has potential as a platform for other valuable chemical intermediates. One example is the aromatic hydrocarbon p-xylene ("pX"), a well-known chemical feedstock in high demand. However, conventional processes for converting biomass conversion by-products such as CMF and MF into intermediates such as MFA, DMF, and pX have struggled in terms of sufficient yield and commercial viability.

[0007] Previous approaches to converting CMF into more useful intermediates have failed, among other problems, in terms of achieving high purity through a commercially viable process and avoiding excess reactants or undesirable by-products. For example, U.S. Patent No. 4,335,049, granted on June 15, 1982, which is incorporated in its entirety by reference, describes the hydrogenation, dechlorination, or reduction reaction of 5-chloromethylfurfural (CMF) on a Pd catalyst to produce 5-methylfurfural (MF) via a basic additive such as a tertiary amine. However, this disclosure does not adequately describe the complete process for producing MF from CMF. When CMF is reduced to MF as described in this disclosure, HCl is produced, which reacts with a tertiary amine base to form an amine-HCl salt. Amine-HCl salts are detrimental to the function and lifetime of the Pd catalyst and result in an exceptionally undesirable turnover number ("TON," the ratio of moles of the product produced to moles of the catalyst before the catalyst becomes inactive). For example, this reference states that the amount of palladium in a batch reaction is 0.001 to 1 mole, preferably 0.0005 to 0.10 moles, or ~1 mole of CMF. This is equivalent to 1 to 1000, preferably 10 to 200 TONs. With such a low turnover, the process becomes commercially unsustainable. Additionally, tertiary amines react with CMF to form undesirable quaternary ammonium salts (amine-CMF salts) via the Menshutkin reaction. Amine-CMF salts are generally insoluble in hydrocarbons, forming solids that clog reactors and cause costly process interruptions. Furthermore, this reference is completely silent on the recovery of amines for reuse.

[0008] Therefore, what is needed is a process that achieves commercial viability by converting furfural, such as biomass conversion by-products—CMF, MF, and MFA—into intermediates such as MFA, DMF, and pX, with sufficient yield and purity, as well as an acceptable number of turnovers.

[0009] The purpose of this disclosure is to describe the process for converting CMF to MF, MFA, DMF, and / or pX. The purpose of this disclosure is also to describe the process for converting MF and / or MFA to DMF and / or pX.

[0010] The purpose of this disclosure is to describe a process for generating MF and / or MFA, which are neutralized when HCl is formed, thereby protecting the function of the Pd catalyst and increasing its lifetime.

[0011] The purpose of this disclosure is also to describe a process for producing MF and / or MFA that minimizes or eliminates the formation of undesirable quaternary ammonium salts.

[0012] The purpose of this disclosure is also to describe a process for producing MF and / or MFA in which amine base additives are recovered and made available for recycling throughout the process. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] U.S. Patent No. 4,335,049 [Overview of the project]

[0014] This disclosure relates to the extraction of valuable chemical intermediates from furfural byproducts of biomass conversion. In particular, this approach relates to a process for converting CMF to MF and / or MFA, MF to MFA, and CMF, MF, and / or MFA to DMF and optionally pX.

[0015] In embodiments of this approach for converting CMF, a CMF stock (e.g., from a biomass conversion process) is reacted with an amine base additive in an organic solvent (e.g., toluene) in the presence of hydrogen to produce an effluent having MF, the amine base additive, and at least one amine-HCl salt. The reaction is preferably carried out on a catalyst, more preferably a Pd catalyst. In some embodiments, the amine-HCl salt is neutralized to produce MF and amine base additive compositions, which can be decanted to produce an MF-rich phase and an amine-rich phase. The amine-HCl salt can be neutralized using a corrosive agent. In such embodiments, the amine-rich phase can be distilled to produce purified amine base additive and amine-MF distillate, the latter of which can be recycled into the decanting process. Alternatively, the MF-rich phase can be distilled to produce purified MF and amine-MF distillate, the latter of which can be recycled into the decanting process. It should be understood that the reaction from CMF to MF can be carried out in one or more batch reactors and / or one or more continuous reactors. In this approach, the reactor may be a backfeed reactor.

[0016] Some embodiments include a CMF stock containing an organically soluble material ("OSM"). In some embodiments, after separation of the organic solvent and amine base additive, the OSM remains in the solution containing the MF. To prevent or minimize solidification of the OSM, the MF and OSM may be separated using a heavy solvent.

[0017] Under this approach, the amine base additive may be a tertiary amine of formula R3N, where each R may be the same or different, and is a linear or branched alkyl, preferably with an average number of carbon atoms in each R being 1 to 12. For example, the amine base additive may be one or more of tri-n-butylamine ("TBA"), tri-isobutylamine ("TiBA"), tris-2-ethylhexylamine ("TEHA"), trihexylamine ("THEX"), dimethyldocecylamine ("DIMLA"), dibutylaniline ("DBAN"), trimethylamine ("TMA"), N,N-diisopropylethylamine ("DIPEA"), tri-n-amylamine, tri-octylamine, and triethylamine ("TEA").

[0018] The organic solvent may be one or more of the following: polar organic solvents, methanol, acetone, dimethylformamide, MF, tetrahydrofuran, furfural, nonpolar organic solvents, benzene, alkylbenzene, xylene, and toluene. The 5-chloromethylfurfural stock preferably contains a CMF concentration of less than 60% by weight, or less than 50% by weight, or less than 40% by weight, or less than 30% by weight, or less than 20% by weight, or less than 15% by weight, or less than 10% by weight, or less than 5%, and these concentrations are ±1% by weight.

[0019] This approach may be characterized by one or more separation operations following the reaction from CMF to MF, and, in some embodiments, after amine-HCl salt neutralization. For example, a first separation may remove the organic solvent, leaving MF, amine base additive, and optional OSM for subsequent separation operations. MF and amine base additive may be separated by decanting to produce amine-rich and MF-rich phases. These phases may then be distilled to produce a pure bottom product, and the distillate product may be returned to the decanting operation.

[0020] In some embodiments, the reactor effluent is mixed and washed with diluted HCl to produce an acid washing mixture of an organic phase having MF and an organic solvent, and an aqueous phase having an amine-HCl salt. The acid washing mixture can be decanted to separate the organic and aqueous phases. The aqueous phase may be neutralized with a base and distilled to produce a recovered amine-base additive product, and the organic phase may be distilled to produce an organic solvent distillate product and an MF bottom product. The latter may be distilled with a strong solvent to produce a pure MF distillate product and a bottom product containing OSM.

[0021] As described herein, the selection of amine base additives and how the amines are added to the process significantly affects several aspects of the process: (i) the solubility of the amines and their derivatives (which is important to avoid solid formation that clogs the reactor), (ii) the ability to recover and reuse the amines, and (iii) the ability to separate the amines from the MF products. In some embodiments, the amine base additive preferably reacts rapidly with HCl to form a neutral amine-HCl salt. In some embodiments, the amine base additive preferably reacts slowly with CMF to form an amine-CMF salt. In some embodiments, the amine base additive and the corresponding amine-HCl salt are soluble in the reaction mixture. In some embodiments, the amine base additive preferably has a boiling point higher than the temperature at which the corresponding amine-HCl salt is thermally decomposed. In preferred embodiments, the amine base additive satisfies one or more of these criteria, most preferably all of them.

[0022] This approach also provides the production of MFA from MF. In such embodiments, MF is reduced in a solvent in the presence of hydrogen and a catalyst. Suitable catalysts can be used. Preferred catalysts include Cu, Pd / C, and Pd / Al2O3 catalysts. Tertiary amines may be incorporated to extend catalyst lifetime and improve selectivity. MFA is an important intermediate of other chemicals, and therefore it should be understood that some embodiments culminate in MFA production. It should also be understood that the conversion from MF to MFA can be derived from the conversion from CMF to MF.

[0023] This approach also provides the production of DMF from MF or MFA. In these embodiments, the reactants (MF or MFA) are reduced in a solvent in the presence of hydrogen and a catalyst. Suitable catalysts may be used. Preferred catalysts include Cu, Pd / C, and Pd / Al2O3 catalysts. Tertiary amines may be selected to extend catalyst lifetime, as described herein. Amine base additives may be selected in relation to the solvent, as described below. It should be understood that DMF is an important intermediate of other chemicals, and therefore some embodiments may conclude with DMF production.

[0024] However, due to the advantages of this approach, some embodiments continue the production of pX from DMF. In such embodiments, the first step is the reduction of the initial reactants (MF or MFA) in a solvent in the presence of hydrogen and a catalyst to produce DMF. In the second step, the DMF is reacted with ethylene in an organic solvent in the presence of an acid catalyst to produce pX. In some embodiments, the same organic solvent is used for both the production of DMF and the production of pX. This is advantageous because it avoids the need to separate the DMF from the initial solvent before producing pX from DMF.

[0025] These and other embodiments will be apparent to those skilled in the art in consideration of the following detailed description, drawings and the claims appended herein.

Brief Description of the Drawings

[0026] [Figure 1] Shows a process for converting CMF to MF according to one embodiment of this approach. [Figure 2] Shows an example of the decant of MF and an amine base additive according to one embodiment of this approach. [Figure 3] Shows the estimated time of 99% CMF conversion versus catalyst charge for 40 wt% and 20 wt% CMF feeds. [Figure 4] Shows MF yield versus catalyst charge at complete CMF conversion. [Figure 5] Shows the molar yield of MF hydrogenation correlated with the time for one embodiment of this approach. [Figure 6] Shows the yields of MF, MFA, and DMF over time at 230 °C. [Figure 7] Shows the molar selectivity of MF hydrogenation at 210 °C and 230 °C. [Figure 8] Shows the molar selectivity of MF hydrogenation at 210 °C and 230 °C. [Figure 9] Shows the molar selectivity over various reaction temperatures. [Figure 10] Shows the molar selectivity correlated with hydrogen pressure in the production of DMF by this approach. [Figure 11] Shows the molar selectivity for different solvents in the production of pX. [Figure 12] Shows the molar selectivity in the production of DMF for different concentrations of TBA at 170 °C and 230 °C, respectively. [Figure 13] Shows the molar selectivity in the production of DMF for different concentrations of TBA at 170 °C and 230 °C, respectively. [Figure 14] Shows the molar selectivity correlated with time with and without TBA as an amine, respectively. [Figure 15] Shows the molar selectivity correlated with time with and without TBA as an amine, respectively. [Figure 16]A flowchart of an embodiment of this approach is shown. [Figure 17] A flowchart of an embodiment of this approach is shown. [Figure 18] A flowchart of an embodiment of this approach is shown. [Modes for carrying out the invention]

[0027] The following description provides embodiments of the approach that are sufficiently detailed to enable its implementation. While the approach is described with reference to these specific embodiments, it should be understood that the approach can be embodied in different forms, and this description should not be construed as limiting the scope of any appended claims to the specific embodiments described herein. Rather, these embodiments are provided so that the disclosure is thorough, complete, and fully conveys the scope of the approach to those skilled in the art.

[0028] This approach relates to processes for converting CMF to MF and / or MFA, MF to MFA, and CMF, MF, and / or MFA to DMF and optionally pX. The reactions can proceed as batch or sequential reactions.

[0029] The conversion of CMF to MF is achieved by combining CMF with hydrogen in the presence of a supporting palladium catalyst. The following reaction [I] proceeds at mild temperatures and pressures. It should be understood that, if necessary, the reaction can continue to produce MFA. [ka]

[0030] This approach also relates to the production of 2,5-dimethylfuran (DMF) or p-xylene (pX) from either 5-methylfurfural (MF) or 5-methylfurfuryl alcohol (MFA). The reaction is shown below as Reaction [II]. It should be understood that DMF can be produced from CMF by first converting CMF to MF and / or MFA. [ka]

[0031] Existing processes for converting CMF, such as U.S. Patent No. 4,335,049 discussed above, suffer from low MF and MFA selectivity and yield, low catalyst lifetime (e.g., fewer than 1,000 turnovers), and the formation of insoluble quaternary salts under typical reaction temperature and pressure conditions. Other existing processes, such as those described in U.S. Patent No. 9,556,137 granted January 31, 2017, and U.S. Patent No. 10,618,880 granted April 14, 2020, both of which are incorporated in whole by reference, are less efficient and require various additional reactants. For example, the aforementioned disclosures require an amide and HCl to convert MF to DMF, respectively. This approach does not require such additional components. Furthermore, the tertiary amines discussed below do not form amides, and hydrogenation is achieved solely through the use of a catalyst in this approach. The previously mentioned prior art processes used HCl to facilitate the reaction with a Pd catalyst.

[0032] This approach for converting CMF overcomes these shortcomings. In embodiments of this approach for converting CMF, a CMF stock is reacted with an amine base additive in an organic solvent (e.g., toluene) in the presence of hydrogen to produce an effluent having MF, an amine base additive, and at least one amine-HCl salt. The reaction proceeds on a Pd catalyst. In some embodiments, the amine-HCl salt is neutralized to produce MF and an amine base additive composition, which can be decanted to produce an MF-rich phase and an amine-rich phase. The amine-HCl salt can be neutralized by the use of a corrosive agent, as discussed below. In such embodiments, the amine-rich phase can be distilled to produce purified amine base additive and amine-MF distillate, the latter of which can be recycled into the decanting process. Similarly, the MF-rich phase can be distilled to produce purified MF and amine-MF distillate, the latter of which can be recycled into the decanting process. It should be understood that the reaction from CMF to MF can be carried out in one or more batch reactors and / or one or more continuous reactors. In this approach, the reactor may be a backfeed reactor.

[0033] This approach involves the use of an amine base additive in the process. In some embodiments, the amine base additive preferably reacts rapidly with HCl to form a neutral amine-HCl salt. In some embodiments, the amine base additive preferably reacts slowly with CMF to form an amine-CMF salt. In some embodiments, the amine base additive and the corresponding amine-HCl salt are soluble in the reaction mixture. In some embodiments, the amine base additive preferably has a boiling point higher than the temperature at which the corresponding amine-HCl salt decomposes thermally. In preferred embodiments, the amine base additive satisfies one or more of these criteria, most preferably all of them.

[0034] In some embodiments, the amine base additive is a tertiary amine having the formula R3N, where the average carbon length of the R group is 2 to 8. Tri-n-butylamine (TBA), also known as N,N-dibutylbutan-1-amine, is an example of a preferred amine base additive under this approach. In some embodiments, the amine base additive is a tertiary amine having the formula R3N, where at least one R group is branched alkyl, preferably branched at the second carbon from the carbon-nitrogen bond. Tri-isobutylamine (TiBA), also known as 2-methyl-N,N-bis(2-methylpropyl)propane-1-amine, is another example of a preferred amine base additive under this approach.

[0035] Under this approach, the amine base additive is a tertiary amine of formula R3N, where each R may be the same or different, and is a linear or branched alkyl, preferably with an average number of carbon atoms in each R of 1 to 12. Shorter chain lengths and primary or secondary amines tend to react more rapidly with CMF to form undesirable, generally insoluble amine-CMF salts. Longer chain lengths (e.g., more than 8 carbon atoms) are generally less soluble in the reaction mixture, although exceptions exist. For example, the amine base additive may be one or more of the following: tri-n-butylamine ("TBA"), tri-isobutylamine ("TiBA"), tris-2-ethylhexylamine ("TEHA"), trihexylamine ("THEX"), dimethyldocecylamine ("DIMLA"), dibutylaniline ("DBAN"), trimethylamine ("TMA"), N,N-diisopropylethylamine ("DIPEA"), tri-n-amylamine, tri-octylamine, and triethylamine ("TEA").

[0036] The following table provides data and experimental measurements of the behavior of various amines and their salts related to this approach. [Table 1] [Table 2]

[0037] Some embodiments include a CMF stock containing an organically soluble material ("OSM"). In some embodiments, after separation of the organic solvent and amine base additive, the OSM remains in the solution containing the MF. To prevent or minimize solidification of the OSM, the MF and OSM may be separated using a heavy solvent.

[0038] The organic solvent may be one or more of the following: polar organic solvents, methanol, acetone, dimethylformamide, MF, tetrahydrofuran, furfural, nonpolar organic solvents, benzene, alkylbenzene, xylene, and toluene. The 5-chloromethylfurfural stock preferably contains a CMF concentration of less than 60% by weight, or less than 50% by weight, or less than 40% by weight, or less than 30% by weight, or less than 20% by weight, or less than 15% by weight, or less than 10% by weight, or less than 5%, and these concentrations are within ±1% by weight. In embodiments of this approach, the reaction is generally carried out at a reaction temperature of 50°C to 150°C, more preferably 90°C to 130°C in some embodiments, and more preferably 100°C to 120°C in some embodiments, and these temperatures are within ±3°C. In embodiments of this approach, the reaction is generally carried out at a hydrogen pressure of 115–515 psia, more preferably 200–400 psia in some embodiments, and more preferably 215–315 psia in some embodiments, with these pressures being within ±5 psia.

[0039] Figure 1 shows a process 100 for converting CMF to MF according to one embodiment of this approach. The reaction is a hydrogenation dechlorination reaction of CMF on a Pd catalyst in the presence of a tertiary amine base, forming MF and an amine-HCl salt. The CMF is diluted to a concentration of less than 50% by weight with an organic solvent. At least one equivalent of an amine base additive is added to the CMF. The drawings use standard symbols used in the field of chemical engineering. The organic effluent 101 containing CMF and an organic solvent (e.g., toluene) enters a first distillation column 103. The organic solvent 102 may be recovered and recycled, and the concentrated CMF 105 enters and exits a series of reactors 107a to 107x, preferably a continuous stirred tank reactor ("CSTR"), and enters and exits on a Pd catalyst in the presence of hydrogen 109 and a tertiary amine 111. In some embodiments, at least one equivalent of an amine base additive 111 may be added stepwise throughout the course of the reaction. Other reactors may be used, but CSTR is advantageous in that it limits or prevents precipitation or amine-CMF quaternary salts. The CMF is preferably diluted in an organic solvent to less than 60% by weight, less than 50% by weight in some embodiments, less than 40% by weight in some embodiments, less than 30% by weight in some embodiments, less than 20% by weight in some embodiments, less than 15% by weight in some embodiments, less than 10% by weight in some embodiments, and less than 5% in some embodiments, with these concentrations being ±1% by weight. CSTR produces an effluent 113 of MF, organic solvent, amine base additive, amine-HCl salt, and OSM. The effluent 113 can be separated to remove hydrogen for hydrogen recycling 115.

[0040] The initial amine-base additive 111 can be recovered from the amine-HCl salt by neutralizing the amine-HCl salt with an aqueous base 119 to form an amine and an aqueous chloride salt, and the amine is separated from the aqueous phase by decantation 121, and wastewater 122 is removed. The reaction can be carried out in a series (two or more) reverse-mixing reactor.

[0041] Following the reaction, composition 113 comprises MF, an organic solvent (e.g., toluene), an amine base additive (e.g., TBA), an amine-HCl salt, and OSM. Advantageously, the OSM formed from the biomass conversion product does not need to be separated at this stage and may remain in the solution until the separation and purification of the MF.

[0042] The organic solvent 120 can be separated from the organic phase effluent by distillation 123, leaving a stream 125 containing MF and amine in phase separation 127, where the MF and amine form the separated MF-rich phase 192 and amine-rich phase 131, which are then separately purified into MF 133 and amine 135 by distillation processes 132 and 134, respectively.

[0043] The organic solvent 120 may be a single compound, as discussed above. However, in some embodiments, the diluent / solvent during the reaction may include a combination of a nonpolar solvent (such as toluene) and a polar solvent such as methanol, acetone, dimethylformamide, MF, tetrahydrofuran, benzene, alkylbenzene, xylene, or furfural.

[0044] As shown in Figure 1, the unreacted amines in the reactor effluent 113 may be reacted with aqueous HCl so that essentially all of the amines are converted to amine-HCl. The aqueous phase (containing amine-HCl) is then separated from the organic phase by decantation. The aqueous phase is neutralized with a base, and the amines are recovered from the aqueous chloride salt by decantation.

[0045] It should be understood that the process shown in Figure 1 is configured for a process involving TBA as an amine base additive. The chemical properties may be modified to accommodate other amine base additives, requiring alterations in the process.

[0046] This approach may be characterized by one or more separation operations following the reaction from CMF to MF, and, in some embodiments, after amine-HCl salt neutralization. For example, a first separation may remove the organic solvent, leaving MF, amine base additive, and optional OSM for subsequent separation operations. MF and amine base additive may be separated by decanting to produce amine-rich and MF-rich phases. These phases may then be distilled to produce a pure bottom product, and the distillate product may be returned to the decanting operation.

[0047] In some embodiments, the reactor effluent is mixed and washed with diluted HCl to produce an acid washing mixture of an organic phase having MF and an organic solvent, and an aqueous phase having an amine-HCl salt. The acid washing mixture can be decanted to separate the organic and aqueous phases. The aqueous phase may be neutralized with a base and distilled to produce a recovered amine-base additive product, and the organic phase may be distilled to produce an organic solvent distillate product and an MF bottom product. The latter may be distilled with a strong solvent to produce a pure MF distillate product and a bottom product containing OSM.

[0048] It should be understood that this approach may involve various combinations of separation processes depending on the specific amine base additive. For example, in some embodiments, the process is: ● A CMF stock containing CMF, OSM, and an organic solvent is reacted with an amine base additive in the presence of hydrogen to produce an effluent containing MF, OSM, an organic solvent, an optional residual amine base additive, and at least one amine-HCl salt. ●The effluent is neutralized with an aqueous base to produce a neutralized mixture of MF, OSM, organic solvent, and the neutralized amine. ●The neutralized mixture is distilled to produce an organic solvent distillate product, as well as a bottom product having MF, OSM, and a neutralized amine. ● Decanting the bottom product generates an amine-rich phase having neutralized amines, and an MF-rich phase having MF and OSM. ●The amine-rich phase is distilled to produce the recovered amine, ●This may include distilling the MF-rich phase to produce the recovered MF product.

[0049] As another example, some embodiments of this approach may include a pyrolysis operation following a different separation sequence. For example, some embodiments include: ● A CMF stock containing CMF, OSM, and an organic solvent is reacted with an amine base additive in the presence of hydrogen to produce an effluent containing MF, OSM, an organic solvent, an optional residual amine base additive, and at least one amine-HCl salt. ●The effluent is thermally decomposed to produce recovered HCl products, organic solvent distillate products, and MF-rich bottom products containing MF, amines, and OSM. ●The MF-rich bottom product is distilled to produce the MF distillate product, as well as the amine-rich bottom product containing amines and OSM. ●This may include distilling the amine-rich bottom product together with a base to produce an amine distillate product and an OSM bottom product. Such embodiments may include, for example, toluene, where the organic solvent is toluene, and TBA or TEHA as an amine base additive.

[0050] As yet another example, some embodiments may include a separation operation to remove the OSM from other components. For example, some embodiments include ●Prepare a CMF slurry containing CMF, OSM, an amine base additive, and an organic solvent. ● Mixing the CMF slurry with an organic alcohol to produce a homogeneous CMF stock containing CMF, an amine base product, an organic solvent, a quaternary salt, and OSM, ●A homogeneous CMF stock is reacted on a Pd catalyst in the presence of hydrogen to produce an effluent containing MF, OSM, an organic solvent, an arbitrary residual amine, at least one amine-HCl salt, and methanol. ●The eluate is neutralized with an aqueous base to produce neutralized elutes of MF, OSM, organic solvent, methanol, and the neutralized amine. ●The neutralized effluent is distilled to produce an amine distillate product, as well as an organic-rich bottom product containing MF, OSM, organic solvents, and methanol. ●The organic matter-rich bottom product is distilled to produce methanol, an organic solvent distillate product, and an MF-rich bottom product having MF, OSM, and a residual organic solvent. ●The MF-rich bottom product is distilled to produce a residual organic solvent distillate product, as well as an MF bottom product containing MF and OSM. ●This may include distilling the MF bottom product in the presence of a strong solvent to produce an MF distillate and an OSM bottom product. In such embodiments, methanol and organic solvent distillate products can be recycled into a homogeneous CMF stock. As will be apparent to those skilled in the art, embodiments may feature amine base additive recovery and separation operations other than those described in the illustrative embodiments. Furthermore, amine base additive recovery and separation operations may depend on the specific organic solvent and / or amine base additive used.

[0051] It should be understood that embodiments of this approach for converting CMF allow for an exceptionally favorable turnover number ("TON," the ratio of moles of the generated product to moles of catalyst before the catalyst becomes inactive). Table 3 below shows data for converting CMF to MF using embodiments of this approach (runs 1-16) and the current process (runs 17-24). The data includes solvent and amine selection, amine ratio to CMF, CMF turnover number (mol CMF / mol Pd catalyst), hydrogen pressure, reaction temperature and time, CMF conversion, MF yield, and MF turnover number. Runs 17-19 are data reported in U.S. Patent No. 4,335,049, and runs 20-24 used the solvent and amine described in U.S. Patent No. 4,335,049 with different packing amounts and conditions. As can be seen, operations 1–16 operated with 7,000–145,000 CMF TONs, 5,000–100,000 MF TONs, high CMF conversion, and high MF yields. In contrast, operations 17–19 had exceptionally low TONs of 20–22 and therefore consumed catalyst at an unacceptable rate. Similarly, operations 20–24 demonstrate that this approach is superior to the current process. For example, operation 20 achieved an MF yield of only 61%, and operation 21 required 22 hours to achieve an MF yield of 91%, but the CMF TON was only 200. CMF TONs increased to 1,000–5,000 in operations 22–24, but the MF yield decreased dramatically (8%, 75%, and 47%, respectively). These data demonstrate the superior performance of this approach for CMF conversion.

[0052] In this approach, increasing the catalyst-to-CMF ratio shortens the reaction time and increases the MF yield. As shown in Figure 3, increasing the catalyst load (expressed as mg Pd / g CMF) reduces the estimated time (expressed as hours) and achieves 99% conversion. Figure 4 shows the MF yield (in molar percent) correlated with the catalyst load (expressed as mg Pd / g CMF) for 99% CMF conversion.

[0053] In some embodiments of this approach for converting CMF, the amine salt formed during the reaction can be neutralized. After the reaction, the amine-HCl salt (e.g., tributylamine hydrochloride in some embodiments) can be neutralized with an aqueous or inorganic base to recover the tertiary amine for reuse. Amine recovery dramatically increases the economic feasibility of the process, at least since amines are expensive chemicals. Inorganic bases that have been valued and found to be effective in neutralizing hydrochlorides include sodium hydroxide (NaOH), sodium bicarbonate (NaHCO3), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), and calcium hydroxide (Ca(OH)2). In neutralization, a molar excess of base may be used to ensure complete neutralization and to accommodate the presence of any chlorinated OSM. A higher base-to-CMF ratio results in a higher amine recovery rate, as the excess base reacts with the amine-HCl salt to release a free amine. In some embodiments, a base-to-amine ratio of 100% to 200% is suitable for maximizing amine recovery, including, for example, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, and 1% increments in between.

[0054] Strong bases such as NaOH can react with carbonyl groups in MF via nucleophilic attack. This reaction can lead to a decrease in MF yield by forming potentially undesirable products such as 5-methylfurfuryl alcohol (MFA) and 5-methylfurfuric acid (MFCA). Furthermore, hydroxide bases can catalyze polymerization reactions, resulting in the formation of oligomeric species that precipitate as solids during the washing process.

[0055] On the other hand, Ca(OH)2 neutralization, in particular compared to NaOH neutralization, offers the advantage of better recovery of the desired components, MF and amines. Note that these bases are not soluble in water or the organic phase, and therefore do not require an aqueous phase, but they are added as solids to the organic effluent. [Table 3]

[0056] In the second process, unreacted amines in the reactor effluent can be titrated with aqueous HCl to convert all amines into amine-HCl salts. These amine-HCl salts are soluble in the aqueous phase and can be separated from the organic phase by decantation. The aqueous phase is then neutralized with a base to "spring" the amines, allowing them to be separated by decantation. This process avoids the need to recover amines from the organic effluent by distillation.

[0057] In some embodiments of this approach, when using tertiary amines with a carbon chain length of 3 to 5 (average of all R groups), the formation of insoluble amine-CMF salts cannot be completely avoided. However, under this approach, the formation rate can be further minimized by implementing one or both of the following techniques.

[0058] The first technique involves the stepwise injection of the amine to minimize the amount of excess amine relative to CMF throughout the reactor. The total amount of amine must be equal to at least one equivalent of amine per CMF in the feed, but the amine-to-unreacted CMF ratio can be minimized by the stepwise injection as the reaction progresses. This technique reduces the reaction rate between the amine and CMF, which tends to form insoluble amine-CMF salts that clog the reactor.

[0059] The second technique involves backmixing of the reactor effluent and reactor feed. This approach reduces the CMF concentration in the reactor. Preferably, the reactor is a fully backmixed reactor, i.e., a CSTR, where the CMF concentration throughout the reactor is equal to the outlet concentration, which is lower than the feed concentration. Minimizing the CMF concentration reduces the reaction rate with the amine, which forms insoluble amine-CMF salts that tend to clog the reactor. Several backmixed reactors in series may be used to achieve a high overall conversion of CMF. In some embodiments, two to six backmixed reactors may be used. In a more preferred embodiment, three backmixed reactors may be used.

[0060] Diluents (solvents) have also been found to help reduce the reaction of CMF that leads to solid formation. In some embodiments, the CMF concentration is maintained below about 60% by weight, preferably below about 50% by weight, and more preferably below about 30% by weight. Nonpolar solvents such as toluene serve as effective diluents. Polar solvents such as methanol, acetone, dimethylformamide, MF, tetrahydrofuran, and furfural can also be effective both as diluents for CMF and as solvents for some decomposition products that may precipitate in nonpolar solvents. Thus, polar solvents, and optionally polar solvents used in combination with nonpolar solvents, can result in longer reactor operating lengths without clogging from solids.

[0061] Another feature of this approach is the separation of the MF product from the amine. In current processes, separating amines such as TBA from MF by distillation is extremely difficult. An azeotrope exists between MF and TBA, containing 60-70% by weight of MF. At temperatures below approximately 60°C, this azeotropic composition phase separates, with an MF-rich phase at the bottom and a TBA-rich phase at the top. These phases can be separately decanted and distilled to form relatively pure MF and pure TBA.

[0062] Figure 2 shows an example of decanting MF and an amine base additive according to one embodiment of this approach. As shown, decanter 201 is supplied with composition 203 containing MF and an amine base additive. The MF-rich phase 205 is passed from decanter 201 to a first distillation column 207 producing pure (e.g., 99%) MF 209, and the top product 211 is returned to decanter 201. The TBA-rich phase 213 is passed from decanter 201 to a second distillation column 215 producing pure (e.g., 99%) TBA 217, and the top product 219 is returned to decanter 201. Embodiments of this approach may take the form of a process for separating MF and TBA. Some embodiments may include a process for separating MF and TBA as a component of a process such as converting CMF to MF.

[0063] Another aspect of this approach relates to the preparation and purification of CMF feedstock. When CMF is produced by hydrolysis of cellulose feedstock using HCl and chloride salts in a two-phase reactor containing organic solvents, small amounts of other byproducts are produced in the organic phase. These byproducts are referred to as organic soluble materials, or OSM. OSM tends to be unstable, and the separation of CMF from OSM can be very difficult. Advantageously, under this approach, it is not necessary to separate CMF from OSM before the hydrogenation and dechlorination reaction that converts CMF to MF. As an additional advantage, OSM undergoes some hydrogenation and dechlorination, improving its stability and value as a renewable fuel and other products.

[0064] In this approach, the dechlorination reaction to convert CMF to MF can be carried out in either a fixed-bed reactor or a continuous stirred tank reactor ("CSTR") containing a precious metal catalyst. In a preferred embodiment of this reaction, an amine base additive is added to remove HCl, thereby improving the catalyst lifetime. The following paragraphs describe possible variations included in the reaction steps.

[0065] Some embodiments may involve stepwise amine implantation. In these embodiments, amine base additives are implanted in a stepwise manner to prevent amine-CMF tetrasalt formation.

[0066] Some embodiments may involve recycling a portion of the products of the reaction from CMF to MF. A portion of the products from the reaction step from CMF to MF is recycled back into the reactor to reduce the concentration of CMF in the incoming feed, thereby slowing the rate of amine-CMF quaternary salt formation.

[0067] In some embodiments, a co-solvent may be added to the incoming composition containing the initial CMF reactants. A co-solvent such as methanol may be used to dissolve the CMF-TBA quaternary salt during the reaction from CMF to MF.

[0068] Following the reaction, the conversion product from CMF to MF contains an organic solvent (e.g., toluene), MF, an optional residual amine base additive, an amine-CMF quaternary salt, an amine-HCl salt, an OSM-amine quaternary salt, and OSM. The proportions of these components will vary depending on the specific embodiment. Following the reaction, embodiments of this approach may include one or more separation processes for separating and recovering the various components of the conversion product, such as MF, HCl, amine, and OSM. The following paragraphs describe various aspects of separation processes that may be included in embodiments of this approach for converting CMF.

[0069] When TEHA is used as an amine base additive, HCl can be recovered through processes such as thermal decomposition. Otherwise, the amine-HCl salt may be neutralized with a corrosive material to liberate the amine from the amine-HCl salt. HCl is lost in the form of NaCl during the neutralization step.

[0070] After corrosive cleaning, the organic phase may be distilled to obtain a solvent (e.g., toluene), MF, amine base additives, and OSM. The distillation sequence can be designed based on the following criteria: Firstly, it is recommended to evaporate the light material only once to reduce the load on both the reboiler and the condenser. Secondly, the high-purity product (e.g., MF) is preferably collected from overhead. This avoids heavy impurities from OSM decomposition in the MF product. Thirdly, it is recommended to perform the most difficult separation as the final step of the separation process. Several embodiments of this approach follow one or more of these criteria. A preferred embodiment follows all three criteria. Naturally, those skilled in the art may choose a separation process that contradicts one or more of these criteria without departing from this approach.

[0071] It should be understood that the mixture of MF and TBA present in some embodiments of this approach is somewhat unique, at least in the sense that the mixture forms a two-phase mixture. However, the two-phase mixture is not a clear separation. The upper layer is TBA-dominant, and the lower layer is MF-dominant. In addition, the MF and TBA system forms an azeotrope, thereby limiting the MF purity to less than 70% by weight. This behavior can be avoided by utilizing the two-phase nature of the MF and TBA mixture. Phase separation may be performed before distillation, producing two high-purity streams. Both the TBA-rich and MF-rich fractions can be distilled separately to obtain nearly pure TBA and MF products in their respective bottom streams. The overhead from these distillations, containing the MF / TBA azeotrope, can be recycled into the phase separation operation.

[0072] Some embodiments may feature an alternative amine recovery procedure. In this alternative, the amine is recovered using a dilute acid followed by corrosive washing, as described elsewhere in this specification. This route avoids the complexity of separating the MF from the amine.

[0073] As discussed above, certain CMF stocks, in particular crude CMF, contain OSM. The inclusion of a strong solvent such as Dowtherm A® (Dow Chemical Company, Midland, MI) or A200® (Shell Chemical Co., Houston, TX) may be added during the distillation operation to prevent the OSM from solidifying.

[0074] While some have advantages, it should be understood that a variety of compounds can be suitable as amine base compounds. Amine evaluation is ongoing, and it should be understood that amine compounds not specifically mentioned herein may demonstrate efficacy in embodiments of this approach. Based on amines screened for the reaction from CMF to MF, tertiary amines having three identical R groups, such as tributylamine (TBA) and trihexylamine (THEX), have proven to be the most successful. Tertiary amines with at least one different R group, such as dimethyldocecylamine (DIMLA) and dibutylaniline (DBAN), have been evaluated and may be effective in some embodiments. DBAN specifically has a phenyl group as one of its R groups. Other aromatic amines, such as aniline, have also been evaluated and may be used. One or more of the R groups may be branched alkyl chains, such as triisobutylamine (TiBA) and tris(2-ethylhexyl)amine (TEHA).

[0075] The operations required for a given embodiment will depend on the amine selection. The following paragraphs describe various embodiments of this approach specific to amine base compounds, along with examples of alternative operations. These are merely illustrative examples of the approach, and it should be understood that modifications to various operations can be made without deviating from the approach. Unit operations common in chemical engineering are illustrated using conventional notation.

[0076] In some embodiments of this approach, CMF is converted to MF using TBA as the amine base compound and toluene as the solvent. The initial feed may be a concentrated and purified CMF feed, but may also contain OSM as described above. The hydrogenation and dechlorination ("HDCl") reaction proceeds in a fixed-bed reactor on a Pd catalyst in a hydrogen environment. Following the HDCl reaction, the reaction products include MF, TBA, toluene, TBA-HCl salt, and OSM. This process continues through hydrogen recovery, acid neutralization using a corrosive agent, and solvent recovery before a decanting operation to separate the pure amine from the pure MF. The distillate overhead may be recycled as discussed elsewhere in this specification. It should be noted that, as used herein, "pure" refers to a composition containing at least 80% by weight of the compound, or at least 85% by weight of the compound, or at least 90% by weight of the compound, or at least 95% by weight of the compound, or at least 99% by weight of the compound.

[0077] In an alternative embodiment, CMF is converted to MF using TBA in a continuous stirred tank reactor. Hydrogen and amines are introduced into the CSTR as shown. Otherwise, the process continues as discussed above with respect to the previous embodiment.

[0078] In another embodiment, CMF is converted to MF using TBA and a fixed bed. In this embodiment, hydrogen is recovered from the reaction product, and then dilute acid washing is used to recover the amine. Following the acid washing, the MF-rich components are distilled to separate the MF from the organic solvent (e.g., toluene), and the aqueous phase containing the TBA-HCl salt is neutralized (e.g., via NaOH) to recover the TBA.

[0079] In a variation of the previous process, CSTR is used in the reaction from CMF to MF. Following the CSTR operation, MF, solvent, and amine can be recovered as described in relation to the previous embodiment.

[0080] In another variation, a fixed-bed reactor is used for the reaction from CMF to MF, and a corrosive agent is used to neutralize the TBA-HCl salt. In this embodiment, the solvent (toluene) is first recovered, and the process then separates the amine and MF phases through decantation, as considered above. Phase separation is effective in overcoming the breakdown of the amine-MF azeotrope. The TBA-rich phase is distilled to produce pure TBA, and the MF-rich phase is distilled to produce MF containing OSM. The distillation overhead is returned to the decanter, as considered elsewhere. A strong solvent is used to prevent or minimize solidification of OSM during distillation to separate MF from OSM.

[0081] In this variation of the process, the reaction from CMF to MF proceeds in CSTR. Following the reaction from CMF to MR, the amine-HCl salt is neutralized using a corrosive agent, and then the solvent is removed to produce the MF-amine product. The MF and amine are separated as described in relation to previous embodiments.

[0082] In another embodiment where the reaction from CMF to MF proceeds on a fixed bed, a dilute acid is used before amine recovery. In this modification, acid washing is used to neutralize the amine-HCl salt before the amine recovery operation. In this alternative method, the amine is recovered using a dilute acid, followed by corrosive washing. The aqueous amine-HCl salt phase is neutralized with a base (e.g., NaOH), and then the amine is recovered. MF and solvent are separated as discussed above, and MF is separated from OSM using a strong solvent as discussed above. It should be understood that this approach avoids the complexity of separating MF from amine-base additives.

[0083] Figure 16 shows an alternative process flow diagram for the previous process. In this embodiment of the present approach, the reaction from CMF to MF proceeds with CMF stock 1600, an amine base additive 1602 supplied to CSTR 1601 in hydrogen 1603, and a Pd catalyst. The composition 1605 exiting reactor 1601 contains MF, a solvent (e.g., toluene), an amine (e.g., TBA), an amine-HCl salt, and OSM. Any unused hydrogen can be recycled 1607 before an acid washing process 1609 using dilute acid 1611. The solvent phase 1613, containing the solvent, MF, and OSM, may be separated from the aqueous phase 1615 having the amine-HCl salt 1612. The solvent (e.g., toluene) may be removed from the solvent phase 1613 as a distillate overhead product 1617, then MF may be removed as a distillate overhead product 1619, and OSM 1623 is removed by the addition of a strong solvent 1621. The amine can be recovered from the aqueous phase 1615 through neutralization 1625 using a base such as NaOH 1627, and subsequently, the amine (e.g., TBA) 1629 and wastewater 1631 are separated by phase separation 1630. In this embodiment, advantageously, TBA is removed via acid washing 1609 before MF recovery to avoid amine-MF azeotropes.

[0084] As mentioned above, other amines may be used as amine base compounds. The required operations may vary depending on the chemical properties inherent to the amine. Figure 17 shows a process flow diagram of the reaction from CMF to MF, where TEHA is the amine base additive. In this embodiment, the CMF stock 1701 and the amine (e.g., TEHA) 1702 are fed into a fixed-bed reactor 1703 and onto a Pd catalyst in hydrogen 1705. After hydrogen recovery 1706, the reactor effluent 1707 contains MF, solvent, TEHA, TEHA-HCl salt, and OSM. TEHA may be difficult to recover as an overhead distillate. However, a pyrolysis operation 1709 may be used to recover HCl 1711 and the solvent (e.g., toluene) 1713, resulting in bottom products of MF 1715 and TEHA 1717 which can be separated via distillation 1719. Advantageously, this embodiment avoids the difficulty of recovering TEHA as an overhead product and also allows for the recovery of HCl through thermal decomposition.

[0085] Figure 18 shows a process flow diagram of a modification of the process in Figure 17, in which an additional distillation step 1801 is used to separate the amine from the OSM. A strong solvent 1803 may be used to separate the amine (e.g., TEHA) as a distillate overhead product 1805 and to recover the OSM as a bottom product 1807. A strong solvent may be used to prevent or minimize OSM solidification, as discussed above.

[0086] Another embodiment has been demonstrated using trimethylamine ("TMA"). In this embodiment, CMF is converted to MF using TMA as an amine base additive. Crude CMF and the amine base additive are fed into a quaternary salt reactor to produce a homogeneous slurry of CMF, TMA, OSM, amine salts of CMF and OSM, and MeOH. It should be understood that MeOH is introduced in the final stage before the reaction of CMF to MF and is recovered for recycling later in the process. The presence of methanol in the slurry is advantageous because the amine adducts, CMF, and OSM are soluble in methanol. The slurry proceeds to a fixed-bed reactor for the reaction of CMF to MF HDCl, and proceeds over a Pd catalyst in hydrogen. Hydrogen is recycled from the reactor effluent, and the residual composition proceeds to amine recovery, solvent recovery, and MF purification operations. In this embodiment, the salts are neutralized with a corrosive agent, and TMA is liberated for recovery as distillate overhead. Next, MeOH and toluene from the bottom product are recovered as overhead distillates, and then a strong solvent is used to remove OSM and produce a pure MF overhead distillate.

[0087] In a modified embodiment using TMA, the MF bottom product can be recovered without additional steps to remove OSM. After neutralization, TMA can be removed as an overhead distillate in a first distillation process, MeOH in toluene can be removed as an overhead distillate in a second distillation process, and finally, MF and toluene can be separated in a third distillation process. This demonstrates the advantages of this approach, where individual operations can be used as needed in a given embodiment and incorporated as necessary to accommodate the chemical properties of amine base additives.

[0088] In some embodiments, TEA is an amine base additive. The process proceeds as described above through a quaternary salt reactor, a reaction from CMF to MF in a fixed-bed reactor, and an amine-HCl salt neutralization operation. However, in this embodiment, the solvents (toluene and MeOH) are first recovered as overhead distillates. Next, the amine is recovered as an overhead distillate, and then the MF is recovered and separated from the OSM using the previously described operation. Depending on the embodiment, additional distillation may be required to remove the solvent from the MF before removing the OSM.

[0089] In a modified TEA embodiment, the reactor effluent proceeds through the amine-HCl salt neutralization operation described above, after which MeOH / toluene is removed and recycled. The TEA is then recovered, and the solvent is separated as an overhead distillate to produce the MF bottom product.

[0090] In some embodiments, the approach takes the form of a process for converting MF and / or MFA to DMF. It should be understood that this process may follow the conversion from CMF to MF and / or MFA discussed above. The following reaction scheme [II] illustrates a reaction according to one embodiment of the approach. MF is first reduced to MFA in the presence of hydrogen and a catalyst. The reaction continues with the reduction of MFA to DMF in the presence of hydrogen and a catalyst. Water is a byproduct of the reduction reaction and can be separated and removed from the reactor(s) using techniques common in the art. It should be understood that the same reaction scheme is applicable to embodiments utilizing MFA as the initial reactant. [ka]

[0091] In the reduction process from MF and MFA to DMF, the reactants (MF or MFA) are reduced in a solvent in the presence of hydrogen and a catalyst. Preferred catalysts include Cu, Pd / C, and Pd / Al2O3 catalysts. In some embodiments using Pd / C or Pd / Al2O3 catalysts, a tertiary amine may be incorporated to extend the catalyst lifetime, as discussed above. As discussed above, selection of the solvent / amine system is preferred.

[0092] Some embodiments of this approach are processes for producing p-xylene from 2,5-dimethylfuran. In these processes, DMF is reacted with ethylene in an organic solvent in the presence of an acid catalyst. The following reaction scheme [III] shows a reaction for producing pX from DMF according to one embodiment of this approach. As can be seen, DMF was reacted with ethylene in the presence of an acid catalyst and an organic solvent to produce pX. Water is a byproduct of the reaction and can be separated and removed from the reactor(s) using techniques common in the art. [ka]

[0093] Also described herein are processes for producing p-xylene from 5-methylfurfural. These embodiments should be understood to be combinations of processes for producing DMF from MF and / or MFA and processes for producing pX from DMF. For example, the reaction schemes of these embodiments are shown in reaction scheme [II], followed by reaction scheme [III]. In such embodiments of this approach, the process first involves reacting 5-methylfurfural with hydrogen in an organic solvent on a metal catalyst. This reaction produces 2,5-dimethylfuran. Embodiments of the process then involve reacting the 2,5-dimethylfuran effluent with ethylene in an acid-catalyzed environment to produce p-xylene. In some embodiments, the 2,5-dimethylfuran effluent from the reduction of 5-methylfurfural is used to produce p-xylene without separation. The p-xylene effluent is then separated from the solvent and any impurities to produce a high-purity p-xylene product. In some embodiments, the solvent may be recycled for use in the reduction of 5-methylfurfural.

[0094] As discussed above, the reaction proceeds in a solvent, preferably an organic solvent. If the solvent is inert to its chemical properties, the choice of solvent should not significantly affect the reaction from MF / MFA to DMF in the vapor phase. However, reactions in stirred tank reactors can result in phase separation with aliphatic solvents. The solubility of MF / MFA in organic solvents is high when the solvent is aromatic rather than aliphatic.

[0095] Examples of preferred organic solvents include toluene, ethylbenzene, p-xylene, mixed xylene, tetralin, naphthalene, methylnaphthalene, C9-C18 aromatic solvents, linear or branched paraffins in the C8-C20 carbon range, and p-diethylbenzene. It should be understood that combinations of two or more solvents may be used, and other solvents may be used. Furthermore, different solvents may be used for the reduction of MF and MFA, as well as for the conversion of DMF to pX, but it may be necessary to separate the solvent from the initial reaction before the second reaction.

[0096] During an exemplary operation of converting MF to DMF using this approach, the following observations were made. ● Observe liquid-liquid separation using both dodecane and Parafol-14 as solvents. ●Phase separation results in lower observed reaction rates. ●When phase separation is observed, the heavy organic phase contains large amounts of 2,5-hexanedione and 2,5-hexanediol. In the presence of an acidic site and water, 2,5-hexanedione equilibrates with DMF and can be used to recover DMF. However, further hydrogenation of 2,5-hexanedione produces 2,5-hexanediol, which does not equilibrate with DMF and therefore cannot be converted back to DMF. ●Lower reaction rates can be explained by mass transfer effects resulting from heterogeneity. Experiments using aromatic solvents such as toluene demonstrated high MF conversion rates and DMF selectivity in a stirred tank reactor.

[0097] The initial concentration of MF and / or MFA in the solvent is preferably 5 to 70% by weight, but it should be understood that the concentration may vary depending on the embodiment. For example, the concentration may be 10% by weight, 20% by weight, 30% by weight, 40% by weight, 50% by weight, 60% by weight, or any 1% by weight increment between those values.

[0098] As discussed above, the reduction reactions of MF and MFA proceed with a catalyst. In preferred embodiments, the catalyst is a transition metal catalyst, more preferably a noble metal catalyst. The catalyst may include an acidic moiety. Three different catalysts have been demonstrated, as described in the illustrative embodiments. These catalysts are bulk Cu catalyst, Pd / C, and Pd / Al2O3. Both Cu and Pd / Al2O3 showed good reactivity compared to Pd / C in the illustrative embodiments. Cu demonstrated higher selectivity compared to Pd / C and Pd / Al2O3, and Pd catalysts appear to favor the ring hydrogenation and ring-opening chemistry. The chemistry is not limited to the two catalysts mentioned above, as other transition metal catalysts may be effective for the chemistry, with groups 9, 10, and 11 being particularly good candidates. For example, Ni and Pt catalysts provide potent catalysts for this approach.

[0099] The MF and / or MFA reduction reaction proceeds in the presence of hydrogen. The hydrogen pressure can be above atmospheric pressure and may be, for example, 100 psig, 200 psig, 300 psig, 400 psig, 500 psig, 600 psig, 700 psig, 800 psig, 900 psig, or 1,000 psig, or any increment between these values. In a preferred embodiment, the hydrogen pressure is at least 500 psig and may be higher depending on the catalyst material, reactor, and equipment used in a particular embodiment. The hydrogen is present in a molar ratio greater than 1.0 relative to furan (MF or MFA), but it should be understood that the optimal ratio for a given embodiment can be determined through the use of the ordinary art of those skilled in the art.

[0100] In some embodiments using either Pd / C or Pd / Al2O3 as a catalyst, a tertiary amine may be incorporated to extend the catalyst lifetime. However, tertiary amines are not effective in extending the lifetime of the bulk Cu catalyst. In some embodiments, the amine is 5.0% by weight or less of the solution (reactants in an organic solvent), and may be less than 4.5% by weight of the solution, or less than 4.0% by weight of the solution, or less than 3.0% by weight of the solution, or less than 2.0% by weight of the solution, or less than 1.0% by weight of the solution, or any increment of 0.1% by weight thereafter.

[0101] Tributylamine (TBA) inhibits ring-opening and hydrogenation activity. This is particularly pronounced with noble metals. It is hypothesized that TBA passivates the acidic moiety necessary for the ring-opening chemical properties to occur.

[0102] The following paragraphs describe an example of this approach for generating the above-mentioned DMF. It should be understood that, without departing from this approach, certain examples may deviate from this disclosure and based on the level of skill of those skilled in the art.

[0103] Exemplary operations were conducted via batch processes including stirred tank reactors and packed bed reactors. Reactions in the stirred tank reactors proceeded in the liquid phase, while reactions in the packed bed reactors proceeded in both the vapor and liquid phases. It should be understood that reactions can proceed continuously. Additionally, the reactions of this approach can be carried out in batch reactors, tubular reactors, continuous stirred tank reactors (CSTRs), or a combination thereof.

[0104] In a series of exemplary runs, DMF was reacted with ethylene in the presence of trifluoromethanesulfonic acid (also known as trifluic acid) and different organic solvents to produce pX. The organic solvents evaluated included, for example, toluene, dodecane, tetradodecane (Parafol-14, Sasol Chemicals), Isopar®-L, and Isopar®-M (ExxonMobil Chemical Co.). Each solvent was evaluated by reducing the DMF concentration in the reactor feed. All evaluated solvents provided similar DMF conversion and pX selectivity. This demonstrates that almost all organic solvents are effective in the reaction, provided the solvent is inert to the chemical properties of Diels-Alder. In preferred embodiments, it should be understood that the organic solvent is heavier than pX, allowing for the recovery of a high-purity pX product.

[0105] Advantageously, this approach facilitates the extension of catalyst lifetime and allows for the selection of reaction conditions that achieve targeted conversion for the reduction of MF and MFA. It should be understood that in some embodiments, the initial reactant is MF, in some embodiments, the initial reactant is MFA, and in other embodiments, the initial reactant is a combination of MF and MFA. Hydrogenation of MF may proceed at low temperatures such as 50–300°C, preferably at temperatures of about 150–190°C, including any 10°C increment within that range, and is not a rate determination step in this approach. Instead, hydrogenation of MFA is a rate determination step and proceeds at higher temperatures. The selectivity for DMF improves as the reaction temperature rises above 170°C, preferably the reaction proceeds at about 180–240°C, more preferably at about 190–230°C. The reduction of MF and MFA may proceed at pressures of 0–1,000 psig or more. Hydrogen can be maintained in the reactor at a pressure of 0 to over 1,000 psig, preferably about 500 psig to over 1,000 psig. Additionally, the reaction may proceed in the liquid phase and / or vapor phase. Hydrogen solubility and reactivity can be improved at higher pressures in the liquid phase, allowing the reaction to proceed. In the examples of disclosure, the baseline reaction proceeded at 500 psig, but it should be understood that it may proceed at, for example, 100 psig, 200 psig, 300 psig, 400 psig, 500 psig, 600 psig, 700 psig, 800 psig, 900 psig, or 1,000 psig. In preferred embodiments, the pressure is at least 500 psig. Preferably, the reaction proceeds at a temperature in the range of about 190 to 240°C, but it should be understood that the optimal temperature will depend on the catalyst used in the particular embodiment. In some embodiments, amines are added to the MF and / or MFA feed to increase DMF selectivity and reduce the chemistry of ring hydrogenation and ring opening. Amines also beneficially extend the catalyst life and service factor of the continuous reactor unit. Some embodiments may feature an additional separation step following the reduction of the MF and / or MFA to produce a purified DMF product.

[0106] The conversion of DMF to pX proceeds at an operating temperature of approximately 150°C to 300°C, or in any 10°C increment within that range. The operating pressure for the conversion of 2,5-dimethylfuran to p-xylene is approximately 500 to 2000 psig, but the reaction can proceed at any pressure within that range, for example, 700 psig, 1,000 psig, 1,200 psig, 1,400 psig, 1,600 psig, 1,800 psig, etc. As mentioned above, this reaction also proceeds with a catalyst. Preferably, the catalyst is a strong acid.

[0107] The following paragraphs describe observations made in a prototype embodiment of this approach using a fixed-bed device and provide guidance for implementing this approach based on the results discussed below.

[0108] DMF selectivity is strongly correlated with reaction temperature. While selectivity for DMF is conversion-dependent, a strong temperature influence is observed. Embodiments of this approach preferably react at 170°C to 240°C. Lower temperatures favor MFA over DMF.

[0109] The incorporation of amines had a more pronounced effect with the Pd catalyst. The amines demonstrated longer flow times without requiring regeneration. Both experiments shown below had comparable productivity, quantified as turnover number, TON, and defined as DMF grams / Pd grams. They also showed tie points under similar conditions and transformations, exhibiting lower deactivation rates and higher selectivity for DMF. In the absence of amines, higher levels of cyclic chemistry were observed. These reactions include ring hydrogenation and ring-opening reactions. Undesirable byproducts are 2,5-hexanedione and its hydrogenation byproducts, as well as 2,5-dimethyltetrahydrofuran.

[0110] A direct correlation exists between hydrogen pressure and conversion. This effect is more pronounced in the liquid phase. Hydrogen solubility may be a limiting factor in the liquid phase in some embodiments. Higher pressures may be used to advance conversion and reduce reactive species that may introduce contaminants. The vapor phase showed a very high increase in conversion (complete conversion). Transition occurred during operation, and conversion increased from 30% to full. Hydrogen and MF have high accessibility to the catalyst and are likely to increase the conversion rate. However, rapid deactivation was observed, possibly from heavy species formed in the vapor phase and deposited on the catalyst.

[0111] The following paragraphs describe observations made in a prototype embodiment of this approach using a batch-stirred tank reactor and provide guidance for implementing this approach based on the results discussed below.

[0112] With respect to catalyst selection, reaction temperature, and reaction time, as shown in reaction scheme [II] above, the formation of DMF from MF can be treated as two consecutive reactions in which MFA is the primary product and DMF is the secondary product. 1. Aldehyde hydrogenation from MF to MFA 2. Alcohol hydrogenation from MFA to DMF

[0113] The second reaction is expected to have a higher activation barrier than the first reaction and is therefore slower. This relative difference in reaction rates can be used to preferentially produce MFA by using less active catalyst, shortening the reaction time, or lowering the reaction temperature. Silica-supported bulk Cu catalysts such as Johnson-Matthey60 / 08P are less active and preferentially promote aldehyde hydrogenation over alcohol hydrogenation. Figure 5 shows the molar yield of MF hydrogenation on JM60 / 08P at 170°C, correlated with time. After 4 hours, 97% of the initial MF is consumed with 100% selectivity for MFA.

[0114] In alternative embodiments, similar MFA yields can be achieved with the same catalyst at higher temperatures and shorter reaction times. Figure 6 shows the MF, MFA, and DMF yields over time at 230°C. After 30 minutes, the conversion of MF is 98%, and the selectivity to MFA is 100%. At 230°C and 1 hour, the conversion of MF is 100%, and the selectivity to MFA is 97%. It should be understood that catalyst selection, reaction time, and reaction temperature can be selected to preferentially produce MFA in high yield.

[0115] The following paragraphs describe a prototype embodiment of this approach using a batch-stirred tank reactor to produce DMF, and provide guidance for implementing this approach based on the results discussed below.

[0116] In some embodiments, Pd is a preferred catalyst for MF to DMF. Pd exhibited higher activity than Cu-based catalysts in continuous processes, and its selectivity to DMF was high when passivated with TBA. However, in batch reactors, Pd / Al2O3 and Pd / C showed poor activity and low selectivity to DMF in the hydrogenation of diluted MF. On the other hand, the CuO / ZnO bulk powder catalyst showed complete conversion of diluted MF and high selectivity to DMF. In the above tests, the molar ratio of Cu to MF was more than two orders of magnitude higher than that of Pd. The two reactions used 2 g of approximately 66 wt% CuO / ZnO catalyst and 0.15 g of 5 wt% Pd / C for 14 g of MF. However, the cost of Pd is more than 3,000 times the cost of Cu on a molar basis. Therefore, it should be understood that Cu-based catalysts should be considered for batch reactor hydrogenation from MF to DMF.

[0117] The effect of initial MF concentration on DMF production was tested for 5 wt% and 40 wt% MF. Hydrogenation was carried out at 170°C and 500 psi for 4 hours using BASF Cu-0313P as a catalyst. The MF-to-Cu ratio was 10:1 for the 5 wt% MF reaction and 100:1 for the 40 wt% MF reaction. MF conversion was 100% at both high and low starting concentrations. However, lower starting MF concentrations favored DMF production compared to higher starting MF concentrations. In fact, lower starting MF concentrations showed greater selectivity for cyclic hydrogenation products such as DMTHF. This coincides with higher MF-to-Cu ratios and promotes deeper hydrogenation products. Finally, no solid or other polymerization products were observed at higher starting MF concentrations. In fact, the C6 molar balance was improved. In embodiments of this approach, higher initial MF concentrations can be used, but higher reaction temperatures and longer reaction times may be required to produce DMF.

[0118] The slower reaction from MFA to DMF is reflected in the time-dependent conversion of MF and the selectivity to MFA and DMF. Figures 7 and 8 show the molar selectivity of MF hydrogenation on BASF-0313P at 210°C and 230°C over 4 hours, respectively. After 30 minutes at 210°C, all MF is consumed, and the selectivity to MFA is 80 mol%. Over the next 3.5 hours, as the MFA is slowly consumed, the selectivity to DMF increases from 20 mol% to 55 mol%. The same trend is observed at 230°C, but the formation of DMF is more preferred. Therefore, in embodiments of this approach, longer residence times favor higher selectivity to DMF.

[0119] Figure 9 shows the molar selectivity across various reaction temperatures. At almost all temperatures tested, the conversion of 40 wt% MF was completed in 4 hours. At 210°C and 250°C, the MF conversion was completed in 30 minutes. However, the final selectivity to DMF at 4 hours increased with temperature from 13 mol% at 170°C to 89 mol% at 250°C. As discussed above, MF is readily hydrogenated to MFA under the conditions of this study, but the hydrogenolysis of MFA to DMF is slow. Higher temperatures increase the selectivity to DMF by increasing the rate of the second reaction. Therefore, in embodiments of this approach, it should be understood that higher temperatures are preferred for higher selectivity to DMF.

[0120] Figure 10 shows the molar selectivity in DMF production using this approach, correlated with hydrogen pressure. As seen in Figure 10, increasing the H2 pressure increases the conversion of MF and the selectivity to DMF after 4 hours on a bulk CuO / ZnO catalyst at 230°C. Therefore, in this approach, higher hydrogen pressures favor higher selectivity to DMF and higher reaction rates.

[0121] In some embodiments for producing pX, the product from the MF to DMF reactor is used without further purification in the DMF to pX reactor. In such embodiments, the solvent should be heavier than pX to facilitate distillation. Since toluene does not meet this requirement, dodecane and Parafol-14 were tested. Figure 11 shows the molar selectivity for different solvents. The selectivity to DMF after 2 hours was low in the dodecane and Parafol-14 solvents, likely due to a decrease in the hydrogenation rate. In toluene, all MF is converted within 30 minutes of reaction time. In dodecane and Parafol-14, the MF conversion is not completed until 1 hour. This rate decrease also applies to the conversion from MFA to DMF. The lower rates in dodecane and Parafol-14 mean that the ultimate selectivity to DMF is lower in both solvents. The lower reaction rate in paraffin solvent may be due to limitations in mass transport, as two organic phases are present in the reactor. Therefore, heavy aromatic solvents (1-methylnaphthalene) are being evaluated in further demonstrations of this approach. The data indicate that aromatic solvents can be considered to prevent phase separation that reduces the reaction rate.

[0122] In prototype embodiments, TBA was included in the reaction mixture because it has been demonstrated to be useful in a continuous MF to DMF process. Figures 12 and 13 show the molar selectivity in DMF production at different concentrations of TBA at 170°C and 230°C, respectively. In these embodiments, Pd / Al2O3 was claimed to be the preferred catalyst, and the inclusion of TBA reduced the selectivity to the ring-hydrogenation product by passivating the catalyst surface. Including TBA in the MF to DMF process introduces the need for a separation or neutralization step before the DMF to pX process. However, MF has a 9:1 MF-to-TBA mass ratio, and therefore its amines would be easier to separate from the MF to DMF product than from the feed.

[0123] As shown in Figures 12 and 13, including TBA in the batch hydrogenation of MF results in a slightly reduced selectivity to DMF after 4 hours of reaction. This is the case at 170°C and 230°C. At lower temperatures, the main product is MFA, and the selectivity to DMF is about 10 mol%, with or without TBA. At higher temperatures, the main product is DMF, and the selectivity to MFA is about 20 mol%, with or without TBA. Figures 14 and 15 show the time-correlated molar selectivity with and without TBA as the amine, respectively. Furthermore, as shown below, the reaction rate over 4 hours is also minimally affected by the presence of TBA. As can be seen, TBA does not alter the activity or selectivity of BASF 0313-P at 170°C–230°C in embodiments of this approach. The decision to include TBA in the feed should be made based on separation and handling constraints.

[0124] The terms used herein are for the sole purpose of describing specific embodiments and are not intended to limit the approach. Where used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context otherwise explicitly indicates. Where used herein, the terms "comprises" and / or "comprising" specify the presence of a described feature, integer, step, operation, element, or component, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0125] This approach can be embodied in other specific forms without departing from its spirit or essential features. Therefore, this embodiment is considered illustrative and non-limiting in all respects, and the scope of the invention is indicated not by the foregoing description but by the claims of the application, and therefore all modifications that fall within the meaning and equivalence of the claims are intended to be encompassed therein. Table 4

Claims

1. A process for converting 5-chloromethylfurfural, wherein the process is The process comprises reacting a stock of 5-chloromethylfurfural ("CMF") in an organic solvent and an amine base additive on a Pd catalyst in the presence of hydrogen to produce an effluent having at least one of 5-methylfurfural ("MF") and 5-methylfurfuryl alcohol ("MFA") and at least one amine-HCl salt.

2. The process according to claim 1, wherein the organic solvent is toluene and the amine base additive is tri-n-butylamine.

3. The process according to claim 1, wherein the Pd catalyst is initially present in a molar ratio of 5,000 to 150,000 CMF to Pd catalyst.

4. The process according to claim 1, wherein the reaction proceeds at a temperature of 50°C to 150°C and a hydrogen pressure of 115 to 515 psi.

5. The process according to claim 1, further comprising neutralizing the at least one amine-HCl salt to produce a composition having at least one of MF and MFA, the organic solvent, and the neutralized amine.

6. The process according to claim 5, wherein at least one of the MF and MFA is MF, and further comprises decanting the MF and the neutralized amine composition to produce an MF-rich phase and an amine-rich phase.

7. The process according to claim 6, further comprising distilling the amine-rich phase to produce a purified amine and an amine-MF distillate.

8. The process according to claim 7, further comprising recycling the amine-MF distillate into a decanting process.

9. The process according to claim 6, further comprising distilling the MF-rich phase to produce purified MF and amine-MF distillates.

10. The process according to claim 9, further comprising recycling the amine-MF distillate into a decanting process.

11. The aforementioned at least one amine-HCl salt is at least one corrosive agent, an inorganic base, sodium hydroxide (NaOH), sodium bicarbonate (NaHCO3). ３ ), magnesium hydroxide (Mg(OH) ２ ), calcium oxide (CaO), and calcium hydroxide (Ca(OH) ２ The process according to claim 5, which is neutralized through ).

12. The process according to any one of claims 6 to 11, wherein the 5-chloromethylfurfural stock further comprises an organically soluble material ("OSM").

13. The process according to claim 12, further comprising separating the MF and the OSM using a heavy solvent in order to prevent or minimize solidification of the OSM, since the OSM remains in the solution containing the MF.

14. The process according to any one of claims 1 to 13, wherein the reaction proceeds in at least one batch reactor.

15. The process according to any one of claims 1 to 13, wherein the reaction proceeds in at least one continuous reactor.

16. The process according to any one of claims 1 to 13, wherein the amine base additive is a tertiary amine.

17. The amine base additive, formula R ３ The process according to any one of claims 1 to 13, wherein the amine having N is a linear alkyl or branched alkyl, provided that each R in the formula is the same or different, and the average number of carbon atoms in each R is between 1 and 12 carbon atoms.

18. The process according to any one of claims 1 to 13, wherein the amine base additive is at least one amine selected from the group consisting of tri-n-butylamine ("TBA"), tri-isobutylamine ("TiBA"), tris-2-ethylhexylamine ("TEHA"), trihexylamine ("THEX"), dimethyldoceylamine ("DIMLA"), dibutylaniline ("DBAN"), trimethylamine ("TMA"), N,N-diisopropylethylamine ("DIPEA"), tri-n-amylamine, tri-octylamine, and triethylamine ("TEA").

19. The process according to any one of claims 1 to 13, wherein the amine base additive is at least one amine selected from the group consisting of TBA, TEHA, and TEA.

20. The process according to claim 2, wherein the 5-chloromethylfurfural stock comprises CMF and at least one organic solvent selected from the group consisting of polar organic solvents, methanol, acetone, dimethylformamide, MF, tetrahydrofuran, furfural, dimethylfuran, nonpolar organic solvents, toluene, benzene, alkylbenzene, and xylene.

21. The process according to claim 1, wherein the 5-chloromethylfurfural stock contains a CMF concentration of less than 60% by weight, or less than 50% by weight, or less than 40% by weight, or less than 30% by weight.

22. The process according to claim 1, further comprising reducing at least one of the MF and MFA in a solvent in the presence of hydrogen and a metal catalyst to produce a 2-5-dimethylfuran ("DMF") effluent.

23. The process according to claim 22, further comprising reacting the DMF effluent with ethylene in the presence of an acid catalyst to produce para-xylene.

24. The process according to claim 5, wherein at least one of the MF and MFA is MFA, and the process further comprises separating the MFA and the neutralized amine by at least one of decantation, liquid-liquid extraction, and distillation to produce an MFA-rich phase and an amine-rich phase.

25. The process according to claim 1, further comprising neutralizing the effluent with an aqueous base to produce a neutralized mixture of at least one of MF and MFA, the organic solvent, the neutralized amine, and at least one aqueous chloride salt.

26. The process according to claim 25, further comprising separating the neutralized mixture by at least one of decantation, liquid-liquid extraction, and distillation to produce an amine-rich phase and at least one of an MF-rich phase and an MFA-rich phase.

27. The process according to claim 23, further comprising reacting the effluent with aqueous HCl to produce an acid washing mixture of an organic phase having at least one of the MF and MFA and the organic solvent, and an aqueous phase having an amine-HCl salt.

28. Decanting the acid washing mixture to produce the organic phase having at least one of the MF and MFA and the organic solvent, and the aqueous phase having an amine base additive, The process according to claim 27, further comprising neutralizing the aqueous phase with a base to produce a recovered amine.

29. The process according to claim 28, further comprising separating the organic phase to produce an organic solvent distillate product and a bottom product comprising at least one of the MF and MFA.

30. The process according to claim 29, further comprising separating the bottom product to produce a high-purity product.

31. The process according to claim 1, further comprising neutralizing the effluent with a solid base to produce a neutralized mixture of at least one of the MF and MFA, the organic solvent, and the neutralized amine.

32. A process for producing 5-methylfurfural ("MF"), wherein the process is A 5-chloromethylfurfural ("CMF") stock having CMF, an organically soluble material ("OSM"), and an organic solvent is reacted with an amine base additive in the presence of hydrogen on a Pd catalyst initially present in a molar ratio of 5,000 to 150,000 CMF to Pd catalyst to produce an effluent having MF, OSM, the organic solvent, and at least one amine-HCl salt, wherein the reaction proceeds at at least one of a temperature of 50°C to 150°C and a hydrogen pressure of 115 to 515 psi to produce the effluent. The aforementioned effluent is thermally decomposed to produce a recovered HCl product, an organic solvent distillate product, and an MF-rich bottom product having the MF, recovered amine, and the OSM. The MF-rich bottom product is distilled to produce an MF distillate product, as well as an amine-rich bottom product containing the amine base additive and the OSM. The process comprises distilling the amine-rich bottom product to produce an amine base additive distillate product and an OSM bottom product.

33. A process for producing 2-5-dimethylfuran ("DMF"), wherein the process is The process comprises reacting one of 5-methylfurfural ("MF") and 5-methylfurfuryl alcohol ("MFA") with hydrogen in an organic solvent and in the presence of a metal catalyst to produce an effluent having DMF.

34. The process according to claim 33, wherein the organic solvent is selected from the group consisting of toluene, ethylbenzene, p-xylene, mixed xylene, tetralin, naphthalene, methylnaphthalene, C9-C18 aromatic solvents, p-diethylbenzene, dimethylfuran, and combinations thereof.

35. The process according to any one of claims 33 and 34, further comprising separating the organic solvent from the effluent to produce a DMF-rich product.

36. The process according to claim 35, further comprising reacting the effluent with ethylene in the presence of an acid catalyst to produce para-xylene in the organic solvent.

37. The process according to claim 36, further comprising separating the organic solvent from the p-xylene effluent to produce a purified p-xylene product.

38. The process according to claim 37, further comprising recycling the separated organic solvent into one of the reactions of MF and MFA.

39. The process according to claim 36, wherein the acid is a strong acid.

40. The process according to claim 33, wherein the metal catalyst is Cu.

41. The process according to claim 40, wherein the acidic portion is present in the catalyst.

42. The process according to claim 33, wherein the reaction of one of 5-methylfurfural and 5-methylfurfuryl alcohol is carried out in a batch reactor, a tubular reactor, or a continuous stirred tank reactor (CSTR), or a combination thereof.

43. The process according to claim 36, wherein the reaction of 2,5-dimethylfuran is carried out in a batch reactor, a tubular reactor, a continuous stirred tank reactor (CSTR), or a combination thereof.

44. The process according to claim 33, wherein the concentration of one of the 5-methylfurfural and 5-methylfurfuryl alcohol is 5 to 70% by weight.

45. The process according to any one of claims 33 to 44, wherein the operating temperature for the reaction of one of the 5-methylfurfural and 5-methylfurfuryl alcohol is in the range of 50 to 300°C.

46. The process according to any one of claims 33 to 45, wherein the operating pressure for the reaction of one of the 5-methylfurfural and 5-methylfurfuryl alcohol is in the range of about 0 to 1000 psig.

47. The process according to any one of claims 33 to 46, wherein the hydrogen is at a pressure in the range of about 0 to 1000 psig.

48. The process according to any one of claims 33 to 47, wherein the hydrogen is present in a molar ratio of more than 0.75 of hydrogen to one of 5-methylfurfural and 5-methylfurfuryl alcohol.

49. The process according to any one of claims 33 to 48, wherein the reaction of 2,5-dimethylfuran proceeds at a temperature in the range of 150°C to 300°C.

50. The process according to any one of claims 33 to 49, wherein the reaction of 2,5-dimethylfuran proceeds at a pressure in the range of 500 to 2000 psig.

51. The process according to any one of claims 33 to 50, wherein the reaction of 2,5-dimethylfuran proceeds with a strong acid catalyst.

52. The process according to any one of claims 33 to 51, wherein an amine is added to the reaction of one of 5-methylfurfural and 5-methylfurfuryl alcohol for at least one of increasing the selectivity of 2,5-dimethylfuran, reducing the chemical properties of ring hydrogenation and ring opening, extending the life of the catalyst, and extending the service factor of the continuous reactor.

53. The process comprises a liquid phase, in which one of the 5-methylfurfural and the 5-methylfurfuryl alcohol is used for 0.1 to 20 hours. － The process according to claim 33, having a gravitational space velocity ("WHSV") of 1.

54. A process for producing 5-methylfurfuryl alcohol ("MFA"), wherein the process comprises: The process comprises reacting a 5-methylfurfural ("MF") stock with hydrogen in an organic solvent and in the presence of a metal catalyst to produce an effluent having MFA.

55. The process according to claim 54, wherein the organic solvent is selected from polar organic solvents, methanol, acetone, dimethylformamide, MF, tetrahydrofuran, furfural, dimethylfuran, nonpolar organic solvents, toluene, benzene, alkylbenene, xylene, and combinations thereof.

56. The process according to claim 54, further comprising separating the organic solvent from the MFA effluent to produce a purified MFA product.

57. The process according to claim 54, wherein the metal catalyst is Cu or Pd.

58. The process according to claim 54, wherein the reaction of the MF is carried out in a batch reactor, a tubular reactor, a continuous stirred tank reactor (CSTR), or a combination thereof.

59. The process according to claim 54, wherein the concentration of the MF stock is 5 to 100% by weight.

60. The process according to claim 54, wherein the organic solvent includes an amine additive.

61. The amine base additive is, Formula R ３ The process according to any one of claims 54 to 60, wherein the amine having N is a linear alkyl or branched alkyl, provided that each R is the same or different, and the average number of carbon atoms in each R is between 1 and 12 carbon atoms.

62. The process according to any one of claims 54 to 61, wherein the amine base additive is at least one amine selected from the group consisting of tri-n-butylamine ("TBA"), tri-isobutylamine ("TiBA"), tris-2-ethylhexylamine ("TEHA"), trihexylamine ("THEX"), dimethyldoceylamine ("DIMLA"), dibutylaniline ("DBAN"), trimethylamine ("TMA"), N,N-diisopropylethylamine ("DIPEA"), tri-n-amylamine, tri-octylamine, and triethylamine ("TEA").

63. The process according to any one of claims 54 to 62, wherein the operating temperature of the reaction of the MF is in the range of 50 to 300°C.

64. The process according to any one of claims 54 to 63, wherein the operating pressure of the reaction of the MF is in the range of about 0 to 1000 psig.

65. The process according to any one of claims 54 to 60, wherein the hydrogen is at a pressure in the range of about 0 to 1000 psig.

66. The process according to any one of claims 54 to 65, wherein the hydrogen is present in a hydrogen-to-MF molar ratio greater than 0.75.

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