Method for wet oxidation regeneration of biomass hydrogenation catalyst involving switching between oxygen and nitrogen atmospheres; biomass hydrogenation method including same

Abstract

The present disclosure provides a system and method for producing a regenerated hydrogenation catalyst for use in the hydrogenation of biomass feedstocks. The method may include a regeneration cycle in which a depleted hydrogenation catalyst is contacted with (a) a first flushing medium comprising a gas phase containing water and oxygen, and (b) a second flushing medium comprising a gas phase containing water and at least 90% by volume of nitrogen. In particular, multiple regeneration cycles may be used to improve the efficiency of removing sulfur-containing impurities from the depleted catalyst.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 480,607, filed January 19, 2023, the contents of which are incorporated herein by reference in their entirety. [Background technology]

[0002] Biomass is one category of potential renewable alternatives to petroleum-based fuels, chemicals, and other products. However, developing efficient, cost-effective, and environmentally friendly technologies for converting biomass into useful products remains a challenge.

[0003] As a promising approach, bioforming processes provide liquid fuels and chemicals derived from the cellulose, hemicellulose, and lignin contained in plant cell walls. For example, cellulose and hemicellulose can be used as feedstocks for various bioreforming processes, including aqueous phase reforming (APR) and hydrodeoxygenation (HDO), a catalytic reforming process that, when integrated with hydrogenation, can convert cellulose and hemicellulose into hydrogen and hydrocarbons, including liquid fuels and other chemical products. APR and HDO methods and techniques are described in U.S. Pat. Nos. 6,699,457, 6,964,757, 6,964,758, and 7,618,612, all to Cortright et al., entitled "Low-Temperature Hydrogen Production from Oxygenated Hydrocarbons," U.S. Pat. No. 6,953,873, all to Cortright et al., entitled "Low-Temperature Hydrocarbon Production from Oxygenated Hydrocarbons," as well as U.S. Pat. Nos. 7,767,867 and 7,989,664, and U.S. Patent Application Publication No. 2011 / 0306804, all to Cortright, entitled "Methods and Systems for Generating Polyols."Various APR and HDO methods and techniques are described in U.S. Patent Nos. 8,053,615, 8,017,818, 7,977,517, 8,362,307, 8,367,882, 8,455,705, and 8,933,281 (all to Cortright and Blommel, entitled "Synthesis of Liquid Fuels and Chemicals from Oxygenated Hydrocarbons"), U.S. Patent No. 8,231,857 (to Cortright, entitled "Catalysts and Methods for Reforming Oxygenated Compounds"), U.S. Patent No. 8,350,108 (to Cortright et al., entitled "Synthesis of Liquid Fuels from and International Patent Application Publication No. WO 2008 / 109877 (to Cortright and Blommel, entitled "Synthesis of Liquid Fuels and Chemicals from Oxygenated Hydrocarbons"), all of which are incorporated herein by reference.

[0004] In certain applications, it may be beneficial to hydrogenate biomass feedstocks to increase their thermal stability before using them as feedstock for APR and / or HDO. At temperatures compatible with APR and / or HDO, sugars are susceptible to thermal decomposition, leading to by-product formation, catalyst degradation, and ultimately shorter times between catalyst regenerations. This problem is circumvented by reacting sugars with hydrogen to form more thermally stable polyols or sugar alcohols.

[0005] Biomass feedstocks contain impurities, such as sulfur-containing moieties, that poison hydrogenation catalysts over time. Catalyst poisoning leads to reduced conversion and yield of polyol and sugar alcohol products. As a result, most industrial applications involve batch or semi-continuous processes that involve replacing spent catalysts with fresh catalysts or regenerating existing catalysts to improve conversion. Frequent hydrogenation catalyst replacement is time-consuming, costly, and can lead to production downtime. Importantly, hydrogenation catalyst poisoning or deactivation is exacerbated when the feedstock contains high sulfur-containing impurities.

[0006] Current methods for regenerating hydrogenation catalysts include multiple hydrogen peroxide washes to remove impurities from spent hydrogenation catalysts. However, hydrogen peroxide over time weakens the catalyst's physical strength, reduces its total surface area, and ultimately reduces its catalytic activity. There remains a need for more efficient and less damaging regeneration systems and methods that restore catalytic activity to hydrogenation catalysts under industrial production conditions. Summary of the Invention

[0007] Described herein are reactor systems and methods for regenerating hydrogenation catalysts used in the hydrogenation of feedstock solutions, such as water-soluble sugars and / or unsaturated hydrocarbon streams derived from biomass. The provided reactor systems and methods offer unique features and advantages over existing regeneration technologies. This is an improvement over current techniques for regenerating catalytic activity, such as hydrogen peroxide-based methods, which tend to degrade the catalyst's surface area and pore structure over time. Furthermore, hydrogen peroxide presents challenges for storage on a commercial scale. The regenerative oxidants provided herein are less expensive than hydrogen peroxide and can be stored on a commercial scale using existing technologies.

[0008] In one aspect, the present disclosure provides a method for hydrogenating biomass. The method comprises the step of: hydrogenating water and oxygenated hydrocarbons (C 2+ O 1+(ii) catalytically reacting a feed stream comprising the oxidized carbon black (O) and the oxidized carbon black (V) with hydrogen in the presence of a hydrogenation catalyst for a hydrogenation duration to produce a first hydrogenation product stream and an aged hydrogenation catalyst. The method may further include subjecting the aged hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst. The regeneration cycle may include (a) contacting the catalyst with a first flushing medium comprising a gas phase comprising liquid water and oxygen, as measured at 25°C and 1 atmosphere for an air treatment duration, to produce an air-treated catalyst, and (b) contacting the air-treated catalyst with a second flushing medium comprising a gas phase comprising liquid water and at least 90% by volume of nitrogen, as measured at 25°C and 1 atmosphere for a nitrogen treatment duration, to produce a regenerated hydrogenation catalyst. The method may further include catalytically reacting the feed stream with hydrogen in the presence of a regenerated hydrogenation catalyst to further produce a second hydrogenation product stream.

[0009] In another aspect, the present disclosure provides a method for producing a regenerated hydrogenation catalyst from an aged hydrogenation catalyst. The method may include catalytically reacting a feedstream having at least one sulfur-containing impurity in the presence of a hydrogenation catalyst to produce an aged hydrogenation catalyst, the aged hydrogenation catalyst containing an amount of sulfur derived from the at least one sulfur-containing impurity in the feedstream. The method may further include subjecting the aged hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst. The regeneration cycle may include (a) contacting the catalyst with a first flushing medium containing a gas phase containing liquid water and oxygen, measured at 25°C and 1 atmosphere for an air treatment duration, to produce an air-treated catalyst, and (b) contacting the air-treated catalyst with a second flushing medium containing a gas phase containing liquid water and at least 90% by volume of nitrogen, measured at 25°C and 1 atmosphere for a nitrogen treatment duration, to produce a nitrogen-treated catalyst. In particular, the amount of sulfur in the nitrogen-treated hydrogenation catalyst is reduced compared to the aged hydrogenation catalyst.

[0010] In some embodiments, the method includes subjecting the nitrogen-treated catalyst to a successive set of regeneration cycles (a) and (b), each with a respective treatment duration, to produce a regenerated hydrogenation catalyst. For example, the conditions (e.g., temperature, pressure, duration, etc.) of one regeneration cycle can be controlled independently of the corresponding conditions of another regeneration cycle.

[0011] In various embodiments, the hydrogenation catalyst of the present process can include ruthenium on carbon (Ru / C). [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 illustrates an exemplary reactor system according to some embodiments of the present disclosure. [Figure 2] Figure 1 shows representative results of sulfur content analysis of effluent samples from a wet oxidation regeneration (WAOR) process for a 2 wt% Ru / C catalyst. Six samples were taken while air was flowing through the reactor (BDL = below detection limit), one sample was taken during the N2 purge, and one final sample was taken during wet reduction. [Figure 3] This figure shows a comparison of four regeneration processes (Regenerations 1 to 4) for a Ru / C catalyst. Regenerations 1 to 3 were all performed with air flow for 24 hours, while Regeneration 4 was performed with air flow for 4 hours. [Figure 4] 1 shows the performance of the Ru / C catalyst as characterized by conversion and hydrogenation reactor inlet temperature. Regenerations are marked with vertical lines, and corn syrup batch changes are shown with gray dotted lines. [Figure 5] FIG. 1 shows sulfur content, conductivity, and pH in the effluent from a “pulse” WAOR process in which the reactor is switched between air and N2 flows every 12 hours. [Figure 6] FIG. 10 shows the sulfur content and conductivity of the effluent from the second pulse regeneration process for the Ru / C catalyst. [Figure 7] FIG. 1 shows sulfur content and conductivity data for a pulse regeneration process using a 30 minute air flow (pulse) for a Ru / C catalyst. DETAILED DESCRIPTION OF THE INVENTION

[0013] Described herein are reactor systems and methods for regenerating hydrogenation catalysts used in the hydrogenation of feedstock solutions, such as water-soluble sugars and / or unsaturated hydrocarbon streams derived from biomass. The provided reactor systems and methods offer unique features and advantages over existing regeneration technologies. A wet oxidation regeneration system, disclosed in co-pending U.S. patent application Ser. No. 17 / 891,093, the contents of which are incorporated herein by reference in their entirety, provides mild reaction conditions that can effectively remove impurities and restore hydrogenation catalytic activity, while additionally maintaining the structural integrity (e.g., surface area, pore volume) of the catalyst. Maintaining the structural integrity and / or catalytic activity of the catalyst over time reduces the number of times the catalyst needs to be replaced over time and / or reduces the frequency of regeneration operations, improving operating economics. The present regeneration system retains the advantages of the system disclosed in U.S. patent application Ser. No. 17 / 891,093. Surprisingly, the present system is adapted to switch atmospheres (e.g., from air to nitrogen) during the regeneration process, providing the additional advantage of effectively regenerating catalysts used in hydrotreating feedstocks having high levels of sulfur-containing impurities, with more efficient regeneration results.

[0014] In one aspect, the present disclosure provides a method for hydrogenating biomass, the method comprising: Water and oxygenated hydrocarbons (C 2+ O 1+ catalytically reacting a feed stream comprising: (I) a first hydrogenation product stream and (II) a depleted hydrogenation catalyst with hydrogen in the presence of a hydrogenation catalyst for a hydrogenation duration to produce a first hydrogenation product stream and a depleted hydrogenation catalyst; subjecting the depleted hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flushing medium comprising a gas phase comprising liquid water and oxygen, measured at 25°C and 1 atmosphere for an air treatment duration, to produce an air-treated catalyst; and (b) contacting the air-treated catalyst with a second flushing medium comprising a gaseous phase containing liquid water and at least 90% by volume of nitrogen, measured at 25°C and 1 atmosphere for the duration of the nitrogen treatment, to produce a regenerated hydrogenation catalyst. producing a regenerated hydrogenation catalyst, comprising: catalytically reacting the feed stream with hydrogen in the presence of a regenerated hydrogenation catalyst to further produce a second hydrogenated product stream; The present invention provides a method comprising:

[0015] The method may be carried out in a reactor system. Referring to FIG. 1 , a representative reactor system 10 is illustrated in accordance with some embodiments of the present disclosure. While the principles disclosed herein may be beneficially implemented on the illustrated reactor system 10, in some embodiments, other reactor system architectures may be used. In particular, the reactor system 10 includes a reactor 12 having a feed inlet 14 that fluidly connects the reactor 12 to a feed conduit 16. A pump 18 may be configured within the feed conduit 16 to transport a feed solution from a feed source 20, such as a reservoir or an upstream process unit, to the reactor 12. The feed conduit 16 may include a heat exchanger 22 for controlling the temperature of the feed solution and a valve 24 for controlling the flow rate of the feed solution to the reactor 12.

[0016] In some embodiments, a suitable feedstock solution contains water-soluble sugars derived from biomass, although other feedstocks can also be used. As used herein, the term "biomass" refers to, but is not limited to, organic materials produced by plants (such as leaves, roots, seeds, and stems) and metabolic waste from microorganisms and animals. Common biomass sources include: (1) agricultural waste, such as corn stalks, straw, seed husks, sugarcane pomace, bagasse, nut shells, and cow, chicken, and swine manure; (2) woody materials, such as wood or bark, sawdust, timber slash, and mill scraps; (3) municipal waste, such as waste paper and yard clippings; and (4) resource crops, such as poplar, willow, switchgrass, alfalfa, prairie blue stream, corn, soybeans, and the like. Feedstocks can be produced from biomass by any means now known or developed in the future, or can simply be by-products of other processes. Sugars can be derived from wheat, corn, sugar beets, sugarcane, molasses, and the like. The sugar is mixed with water to provide an aqueous feed solution having a concentration effective for hydrogenating the sugar. Generally, suitable sugar concentrations range from about 5% to about 70%, with a range of about 40% to 70% being more common for industrial applications.

[0017] Additionally or alternatively, suitable feedstock solutions include oxygenated hydrocarbons (C 2+ O 1+ , e.g., cyclic ethers, esters, ketones, lactones, carboxylic acids), vegetable oils (e.g., polyunsaturated fatty acids), olefins (e.g., C3-C 12 In some embodiments, the feed stream may be a mixture of water and oxygenated hydrocarbons (C), alkenes and aromatics such as olefins, alkynes, aldehydes, imines, nitriles, thiols, disulfides, thioesters, thioethers, phenols, other arenes / aromatic compounds, and combinations thereof. 2+ O 1+ In some embodiments, the oxygenated hydrocarbon is a saccharide.

[0018] Referring again to FIG. 1 , reactor 12 includes a hydrogen inlet 26 that fluidly connects reactor 12 to a hydrogen conduit 28. A gas delivery device 30 may be configured within hydrogen conduit 28 to deliver hydrogen to reactor 12 from a hydrogen source 32, such as a reservoir or an upstream process unit. In some embodiments, hydrogen conduit 28 includes a heat exchanger 34 configured to control the heat of the hydrogen flow. Suitable gas delivery devices 30 include, but are not limited to, a compressor or a blower. While hydrogen inlet 26 and feedstock inlet 14 are oriented co-currently in FIG. 1 , it should be understood that hydrogen inlet 26 may be positioned counter-currently (i.e., fed to the bottom of reactor 12). Hydrogen conduit 28 may include a valve 36 to control the flow rate of hydrogen to reactor 12. While not shown in FIG. 1 , the feedstock and hydrogen may be blended, mixed, or otherwise combined in a mixer before being fed to reactor 12.

[0019] In some embodiments, reactor 12 includes a hydrogenation catalyst 38 disposed therein. The hydrogenation reaction can be carried out in any reactor of suitable design, including continuous flow, batch, semi-batch, or multi-system reactors, without limitation as to design, size, shape, flow rate, etc. Reactor system 10 can also use a fluidized catalyst bed system, a swing bed system, a fixed bed system, a moving bed system, or a combination of the above. The reactions of the present disclosure are typically carried out using a continuous flow system in steady-state equilibrium.

[0020] In some embodiments, the reactor system 10 operates as a fixed trickle-bed reactor with a shell-and-tube heat exchanger, where hydrogen and feed solution are introduced at the top of the reactor 12 and flow downward over a fixed bed of hydrogenation catalyst 38. The advantages of trickle-bed reactors include simple mechanical design, straightforward operation, and potentially simplified catalyst development. The primary design challenge is ensuring that the heat and mass transfer requirements of the reaction are met. The primary operational challenges of a trickle-bed reactor are achieving uniform loading of the hydrogenation catalyst 38, uniform introduction of the gas and liquid feeds, and avoiding bypass of portions of the hydrogenation catalyst 38 due to channeling of the reactants as they flow through the reactor 12.

[0021] In some embodiments, the reactor system 10 operates as a slurry reactor. While trickle-bed reactors are loaded with immobilized hydrogenation catalyst 38, slurry reactors contain a flowing mixture of reactants, products, and hydrogenation catalyst 38 particles. Maintaining a uniform mixture throughout the reactor 12 involves active mixing via a mixer or pump. Furthermore, to remove the product, the catalyst particles must be separated from the product and unreacted feed by filtration, settling, centrifugation, or some other means. The primary advantage of a slurry reactor is that active mixing may allow for greater heat and mass transfer rates per unit of reactor volume.

[0022] In some embodiments, the feedstock solution and hydrogen are reacted within the reactor 12 by passing through the hydrogenation catalyst 38. In some embodiments, the heat exchangers 22, 34 heat the feedstock solution and hydrogen streams to temperatures between 5°C and 700°C, between 10°C and 500°C, between 20°C and 300°C, or between 50°C and 180°C. In some embodiments, the pressure of the reactor 12 is maintained between 0 psig and 5000 psig, or between 100 psig and 3000 psig. The hydrogenation catalyst 38 may be configured within the reactor 12 in various configurations, including, but not limited to, a single fixed bed or a shell-and-tube arrangement. In some embodiments, the reactor system 10 includes a heating system configured to supply heat to the reactor 12 to maintain a desired operating temperature. In some embodiments, the heating system supplies heat to the reactor 12 using, for example, a heating element (e.g., an electric heater), a heated fluid, or a combination thereof. The heating system may be configured external to the reactor. Additionally or alternatively, the heating system may be configured in a shell-and-tube configuration, where the heating fluid supplies heat to the hydrogenation catalyst 38 through the shell or tube side. In some embodiments, the temperature of the reactor 12 may also be controlled by recycling the reaction products back through the reactor 12 to reduce the exotherm due to the reaction.

[0023] The product stream exits reactor 12 through at least one reactor outlet 50 and is optionally transported via product conduit 52 to separator 54. In some embodiments, product conduit 52 includes a heat exchanger 56 for adjusting the temperature of the product stream before entering separator 54. Separator 54 can optionally separate unreacted hydrogen from unreacted reactants and products. The unreacted hydrogen can be recycled to hydrogen source 32 via hydrogen recycle conduit 58. Any suitable separator 54 can be used to separate the hydrogen from unreacted reactants and products, including, but not limited to, a settling tank, a flash tank, a distillation, or a combination thereof. Although not shown in FIG. 1 , in some embodiments, reactor 12 may include a gas outlet and a liquid outlet, in which case disengagement of vapor and liquid products occurs within reactor 12 without separator 54.

[0024] In some embodiments, separator 54 includes a product outlet 60 that places separator 54 in fluid communication with a second separator 62 via a conduit 64. A pump 66 can transport the product stream and unreacted reactants to second separator 62. A heat exchanger 68 can control the temperature of the product stream and unreacted reactants entering second separator 62, and a valve 70 can regulate the flow rate.

[0025] In some embodiments, second separator 62 is configured to separate the product stream from unreacted reactants. The unreacted reactants are recycled to feed conduit 16 via recycle conduit 72 or otherwise discarded from the process. The product stream exiting separator 62 via product conduit 74 may be sent to storage or to a downstream processing unit 76, such as an aqueous phase reforming (APR) or hydrodeoxygenation (HDO) system. Any suitable separator 62 for separating the product stream from unreacted reactants can be used, including, but not limited to, distillation, evaporation, liquid-liquid extraction, chromatography, or a combination thereof.

[0026] catalyst The method can be used to regenerate hydrogenation catalysts, such as those used in the hydrogenation of biomass. In some embodiments, a suitable hydrogenation catalyst 38 for reactor system 10 comprises a hydrogenation catalyst 38 having an active metal and a support. Suitable active metals include, but are not limited to, Fe, Ru, Co, Pt, Pd, Ni, Re, Cu, alloys thereof, and combinations thereof, used alone or in combination with a promoter such as Ag, Au, Cr, Zn, Mn, Mg, Ca, Cr, Sn, Bi, Mo, W, B, P, and alloys or combinations thereof.

[0027] The hydrogenation catalyst can also include any one of several supports, depending on the desired functionality of the catalyst. Exemplary supports include transition metal oxides, oxides formed from one or more metalloids, and reactive nonmetals (e.g., carbon). Non-limiting examples of supports include, but are not limited to, carbon, silica, alumina, zirconia, titania, vanadia, ceria, silica-aluminate, zeolites, kieselguhr, hydroxyapatite, zinc oxide, chromia, and mixtures thereof.

[0028] In some embodiments, the catalyst is a ruthenium-on-carbon (Ru / C) hydrogenation catalyst. In some embodiments, the catalyst comprises about 0.1 wt.% to about 5 wt.% ruthenium supported on carbon particles, including, but not limited to, about 0.5 wt.%, 1.0 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.%, 2.0 wt.%, 2.5 wt.%, 3.0 wt.%, 3.5 wt.%, 4.0 wt.%, and 4.5 wt.%. In some embodiments, the catalyst comprises about 0.1 wt.% to about 4.0 wt.% or about 1.0 wt.% to about 2.0 wt.% ruthenium-on-carbon. The catalyst may be in the form of an extrudate, tablet, sphere, granule, powder, foam, coated structure, or a combination thereof.

[0029] Catalysts may be deactivated during the reaction or chemical process they catalyze. For example, the hydrogenation catalysts described herein may be deactivated during a biomass hydrogenation process. A catalyst may have a surface with active sites, which may affect its ability to catalyze a hydrogenation reaction. A catalyst may be deactivated during the hydrogenation process for various reasons, including, for example, blocking of the active sites by physical absorption (or adhesion) of bulky molecules, poisoning of the active sites by impurities in the feedstock, or a combination thereof. Catalyst poisoning may be caused, for example, by chemical reactions or strong interactions between impurities (e.g., sulfur-containing compounds) and the active sites of the catalyst, thereby reducing the catalyst's ability to catalyze a hydrogenation reaction, i.e., deactivating the catalyst. The degree of catalyst deactivation may increase over time as the hydrogenation process continues. Even if the amount of impurities in the feedstock may be relatively small, they may accumulate in large quantities over time and adversely affect catalytic activity.

[0030] "Fresh" catalyst is used to mean a catalyst that has not been exposed to impurities from the feed solution or feedstock under hydrogenation conditions.

[0031] As used herein, "aged hydrogenation catalyst" or "aged catalyst" refers to a hydrogenation catalyst whose active sites have been at least partially deactivated due to its use in a hydrogenation process (i.e., exposure to a feed solution under conditions for hydrogenating the feed solution using the catalyst). The extent of degradation may be affected, for example, by the composition of the catalyst, the duration and conditions of the hydrogenation process, the composition of the feed, and the amount of impurities in the feed.

[0032] As used herein, "regenerated hydrogenation catalyst" or "regenerated catalyst" refers to a depleted catalyst whose catalytic activity has been at least partially restored, for example, by removing deposits and / or accumulated impurities from the catalyst surface, restoring access to active sites, restoring poisoned active sites, or a combination thereof. As described herein, a regenerated catalyst may be reused in a hydrogenation process and become a depleted catalyst again during the process. In such a situation, the regenerated catalyst may also be referred to as a "freshly regenerated" catalyst, as opposed to the depleted catalyst produced from such regenerated catalyst.

[0033] The catalytic activity of the regenerated catalyst, or the catalytic activity of the depleted catalyst from which the regenerated catalyst is generated, may be compared to the catalytic activity of a fresh catalyst. For example, the catalytic activity of the depleted catalyst may be about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the catalytic activity of the fresh catalyst. For example, the catalytic activity of the regenerated catalyst may be about 80%, about 90%, about 95%, about 99%, about 100%, or about 110% of the catalytic activity of the fresh catalyst. In some embodiments, the regenerated catalyst has a higher catalytic activity than the depleted catalyst from which the regenerated catalyst is generated. For example, the regeneration methods herein can restore at least a portion of the catalytic activity of the depleted catalyst, thereby improving the catalytic activity of the regenerated catalyst. In some embodiments, the catalytic activity of the regenerated catalyst may be about 105% to about 500%, e.g., about 120%, about 150%, about 200%, about 300%, about 400%, or about 500%, of the catalytic activity of the depleted catalyst from which the regenerated catalyst is generated.

[0034] The catalytic activity of a catalyst (e.g., a fresh catalyst, an aged catalyst, or a regenerated catalyst) can be measured by the conversion of a reagent in a feedstock in a reaction (e.g., a hydrogenation reaction) catalyzed by such a catalyst. As used herein, the term "conversion" of a hydrogenation catalyst refers to the conversion of the hydrogenation catalyst over the duration of the reactants in the feedstock solution (e.g., at least 1 hour to at least 1 day) after exposure to the feedstock solution for a hydrogenation cycle. The hydrogenation catalyst may be a fresh catalyst, an aged catalyst, or a regenerated catalyst. As used herein, the conversion (X) of a particular feedstock reactant is defined as i ) can be calculated as follows:

[0035]

number

[0036] In some embodiments, reactor system 10 includes a pretreatment unit or step for treating the feedstock solution and / or hydrogenation catalyst 38. For example, hydrogenation catalyst 38 may be reduced to an active state. For example, the catalyst may be reduced during production and then passivated with low levels of oxygen in certain applications to enhance catalyst stability when exposed to air. The purpose of the reduction step is to convert any oxidized catalyst to a fully reduced state. For certain feedstock solutions, a pretreatment step may be included upstream of reactor system 10. For example, sugars containing glycosidic bonds (e.g., sucrose) may be hydrolyzed prior to hydrogenation in reactor 12.

[0037] Catalyst Regeneration During hydrogenation, catalytic impurities may accumulate on the surface of the hydrogenation catalyst 38, reducing catalytic performance. As used herein, the term "catalytic impurity" or "impurity" refers to impurities that form deposits that accumulate on catalytic sites on the surface of the hydrogenation catalyst 38, limiting access to the catalytic sites and / or reducing catalytic activity over time (i.e., resulting in reduced product conversion and yield). Exemplary catalytic impurities include, but are not limited to, carbon-containing impurities, sulfur-containing impurities, silicon-containing impurities, phosphorus-containing impurities, or iron-containing impurities.

[0038] In some embodiments, the hydrogenation catalyst 38 is regenerated by contacting the hydrogenation catalyst 38 with a flushing medium to form a regenerated catalyst. In some embodiments, the flushing medium comprises a gas phase or a gas phase and a liquid phase. Unless otherwise specified, the terms "gas phase" and "gas phase" are used interchangeably herein with respect to the flushing medium, and the physical properties of the "gas phase" and "liquid phase" of the flushing medium are understood to be measured at 25° C. and 1 atmosphere pressure. For example, the flushing medium may comprise water as the liquid phase and air or nitrogen in the gas phase, measured at 25° C. and 1 atmosphere pressure.

[0039] Continuing with reference to FIG. 1 , the reactor 12 includes a gas-phase inlet 78 that fluidly connects the reactor 12 to a gas-phase source 80 via a gas-phase conduit 82. A fluid transporter 84 (e.g., a compressor or blower) may be configured within the gas-phase conduit 82 to transport the gas phase from the gas-phase source 80 to the reactor 12. The gas-phase conduit 82 may include a heat exchanger 86 for controlling the gas-phase temperature of the flashing medium and a valve 88 for controlling the flow rate of the gas phase to the reactor 12. In some embodiments, the fluid transporter 84 is configured for direct atmospheric recovery or atmospheric recovery, where the fluid transporter 84 is in fluid communication with or directly in fluid communication with air for compression. Using air as the gas phase of the flashing medium provides various advantages. In particular, using air eliminates the need to purchase and store other oxidizing agents (e.g., hydrogen peroxide) on-site. In some embodiments, the gas-phase source 80 includes a gas phase containing, for example, about 0.1% to about 30% oxygen by volume. In some embodiments, gas-phase source 80 includes an inert gas (e.g., nitrogen, argon, helium, neon, krypton, xenon, radon, or a combination thereof) source and an oxygen source (e.g., a compressed tank), which can be used to modify the O and / or inert gas content of the gas phase to the concentrations described herein. In some embodiments, gas-phase source 80 includes at least 50% air by volume, e.g., at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% air by volume. In some embodiments, gas-phase source 80 includes at least 90% nitrogen by volume, e.g., at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% nitrogen by volume. By adjusting the type of gas (e.g., air or inert gas) supplied via gas phase source 80, the oxidizing atmosphere of the flushing medium (e.g., as measured by the amount of oxygen in the gas phase) can be engineered.

[0040] In some embodiments, reactor 12 includes a liquid phase inlet 90 that fluidly connects reactor 12 with a liquid phase source 92 via a liquid phase conduit 94. In some embodiments, the liquid phase includes water. A pump 96 may be configured within liquid phase conduit 94 to transport the liquid phase from liquid phase source 92 to reactor 12. Liquid phase conduit 94 may include a heat exchanger 98 for controlling the liquid phase temperature of the flashing medium and a valve 100 for controlling the flow rate of the liquid phase to reactor 12. Although not shown in FIG. 1 , the liquid and gas phases may be blended, mixed, or otherwise combined in a mixer before being fed to reactor 12.

[0041] In some embodiments, regenerated hydrogenation catalyst can be generated by maintaining contact of a flashing medium with the hydrogenation catalyst 38 at a regeneration temperature, a regeneration pressure, and for a duration sufficient to remove at least a portion of the impurities from the hydrogenation catalyst 38. Contacting the flashing medium with the hydrogenation catalyst 38 can be carried out in any suitable flow scheme, including continuous flow of the flashing medium over the hydrogenation catalyst 38 (with no recycle), continuous flow of the flashing medium over the hydrogenation catalyst 38 (with partial or total recycle), batch flow, or semi-batch flow. In some embodiments, the flashing medium exits the reactor 12 through the reactor outlet 50 and is recycled to the flashing medium source 80, 92 or the reactor inlet 78, 90 by controlling the flow rate in the product conduit 52 with a valve 102. The liquid phase (e.g., water) and gas phase (e.g., air or nitrogen) of the flashing medium can be recycled several times before being replaced with fresh flashing medium. The "recycle rate" refers to the ratio of recycled material (e.g., water) to fresh material. The present system may allow for high recirculation rates (e.g., 6, 7, 8, 9, or 10) using water as the liquid phase of the flushing medium (e.g., a recirculation rate of 10 corresponds to 10 equivalents of water recycled per equivalent of fresh water introduced into the system). High recirculation rates may reduce water consumption, which is particularly advantageous on a mass production scale.

[0042] Regeneration Cycle In some embodiments, the first flushing medium comprises liquid water and a gas phase comprising at least 0.1% oxygen by volume, including, but not limited to, at least 0.5%, at least 1%, at least 2%, at least 5%, at least 8%, at least 10%, at least 12%, at least 15%, at least 18%, at least 20%, at least 25%, at least 30%, or at least 35% oxygen by volume, measured at 25°C and 1 atmosphere. In some embodiments, the oxygen content of the gas phase of the first flushing medium is between about 0.1% and about 30% by volume, e.g., between about 0.5% and about 30% by volume, between about 1% and about 30% by volume, between about 1% and about 25% by volume, between about 1% and about 20% by volume, or between about 5% and about 20% by volume. In some embodiments, the oxygen content of the gas phase of the first flushing medium is between about 5% and about 20% by volume. In some embodiments, the oxygen content of the gas phase of the first flushing medium is about 1 vol%, about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%, or about 25 vol%. In some embodiments, the oxygen content of the gas phase of the first flushing medium is about 20 vol%. The gas phase of the first flushing medium may further include an inert gas. The inert gas may be, for example, nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide, or a combination thereof.

[0043] The gas phase of the first flushing medium can have the same or similar composition as air. In some embodiments, the first flushing medium comprises a gas phase comprising liquid water and at least 50% air by volume, including, but not limited to, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% air by volume, measured at 25°C and 1 atmosphere. In some embodiments, the gas phase of the first flushing medium consists of air. As used herein, "air" refers to the gas surrounding the Earth, which may vary by region and depend on various factors such as temperature and pressure. As an example, the term "air" may refer to a gaseous composition consisting of, in dry volume percentage (vol%), about 78 vol% nitrogen, about 20.9 vol% oxygen, about 0.9 vol% argon, about 0.04 vol% carbon dioxide, and other elements and compounds such as helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, and ammonia. In this example, a gaseous phase containing at least 50 vol% air contains at least 10 vol% oxygen. As non-limiting examples, the gaseous phase of the first flushing medium may be air, a mixture of air and nitrogen, a mixture of air and oxygen, a mixture of oxygen and nitrogen, or a mixture of oxygen and one or more inert gases. The oxygen and nitrogen contents (net vol%) in some exemplary gaseous phases of the first flushing medium (made with the feed gas) are as follows:

[0044] [Table 1]

[0045] The method may include maintaining contact of the hydrogenation catalyst with the first flushing medium for an air treatment duration to produce an air-treated catalyst. As used herein, the terms "air treatment," "air treated," "oxygen treatment," "oxygenated," and the like refer to treatment with air or any other natural or artificial gas composition containing oxygen. The air treatment duration may be at least 30 minutes, including, but not limited to, at least 1 hour, at least 2 hours, at least 4 hours, at least 8 hours, at least 12 hours, or at least 24 hours. In some embodiments, the air treatment duration is from about 2 hours to about 8 hours, e.g., from about 2 hours to about 4 hours.

[0046] In some embodiments, the second flushing medium comprises liquid water and a gas phase comprising at least 90% by volume nitrogen, including, but not limited to, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% by volume nitrogen, measured at 25° C. and 1 atmosphere. In some embodiments, the gas phase of the second flushing medium comprises at least 95% by volume nitrogen. In some embodiments, the gas phase of the second flushing medium comprises at least 99% by volume nitrogen. In some embodiments, the gas phase of the second flushing medium consists of nitrogen. In some embodiments, the gas phase of the second flushing medium is essentially free of oxygen. As used herein, the term “essentially free of oxygen” refers to less than 1%, or less than 0.5%, or less than 0.1%, or less than 0.05% oxygen.

[0047] The gas phase of the second flushing medium may have a different composition from the gas phase of the first flushing medium. In particular, the gas phases of the first and second flushing media may differ with respect to their oxygen content (e.g., by volume percent). In some embodiments, the gas phase of the second flushing medium has an oxygen content less than that of the gas phase of the first flushing medium. As a result, the catalyst may be exposed to a more oxidizing atmosphere by contacting it with the first flushing medium, and subsequently exposed to a less oxidizing or even inert atmosphere by contacting it with the second flushing medium. In certain embodiments, the gas phase of the first flushing medium contains about 5% to about 20% oxygen by volume (e.g., air or a similar gas composition having about 20% oxygen), and the gas phase of the second flushing medium is essentially free of oxygen (e.g., 99% or more nitrogen).

[0048] The method may include maintaining contact of the hydrogenation catalyst with the second flushing medium for a nitrogen treatment duration to produce a regenerated hydrogenation catalyst. The nitrogen treatment duration may be at least 30 minutes, including, but not limited to, at least 1 hour, at least 2 hours, at least 4 hours, at least 8 hours, at least 12 hours, at least 24 hours, or at least 48 hours. In some embodiments, the nitrogen treatment duration is about 4 hours to about 24 hours, e.g., about 12 hours to about 24 hours. In some embodiments, the nitrogen treatment duration is about 20 hours.

[0049] The air treatment duration and nitrogen treatment duration in a given regeneration cycle can be adjusted and tailored based on other conditions of the regeneration cycle, such as temperature, pressure, and recirculation rate of the flushing medium, to achieve the desired regeneration results. For example, in a regeneration cycle, the air treatment duration can be 2-4 hours, the nitrogen treatment duration can be about 20 hours, and the flushing medium can be recirculated at a recirculation rate of 6-10 (e.g., a recirculation rate of 8).

[0050] Contact between the first or second flushing medium and the catalyst can be carried out, for example, by flowing the flushing medium over the surface of the catalyst. Contact can be maintained by controlling the flow rate of the flushing medium over the air treatment duration and the nitrogen treatment duration. As described herein, both the liquid and gaseous portions of the flushing medium can be recirculated (as designed by the recirculation rates described herein), and the system can provide a continuous flow of recycled flushing medium to maintain contact between the first or second flushing medium and the catalyst. Typically, contact between the gaseous component of the first flushing medium and the catalyst is stopped (e.g., turned off) before contact between the gaseous component of the second flushing medium and the catalyst is initiated (e.g., turned on). When multiple regeneration cycles are performed, contact between the second gaseous component of the flushing medium and the catalyst in the last cycle is typically stopped before contact between the gaseous component of the first flushing medium and the catalyst in the next cycle is initiated. Thus, the present system allows for exposure of the catalyst to dramatically different atmospheres (eg, from primarily air to primarily nitrogen) in a single regeneration cycle or from one regeneration cycle to another.

[0051] In some embodiments, the regeneration temperature is between 50° C. and 200° C. In some embodiments, the regeneration temperature is at least 50° C., or at least 60° C., or at least 70° C., or at least 80° C., or at least 90° C., or at least 100° C., or at least 110° C., or at least 120° C., or at least 130° C. to less than 140° C., or less than 150° C., or less than 160° C., or less than 170° C., or less than 180° C., or less than 190° C., or less than 200° C. In some embodiments, the regeneration cycle is carried out at a temperature of between about 70° C. and about 120° C.

[0052] In some embodiments, the regeneration pressure is between 20 psig and 300 psig. In some embodiments, the regeneration pressure is at least 20 psig, or at least 30 psig, or at least 40 psig, or at least 50 psig, or at least 60 psig, or at least 70 psig, or at least 80 psig, or at least 90 psig, or at least 100 psig to less than 110 psig, or less than 125 psig, or less than 150 psig, or less than 200 psig, or less than 250 psig, or less than 300 psig. In some embodiments, the regeneration cycle is conducted at a pressure between about 50 psig and about 200 psig.

[0053] In some embodiments, the flow of the gas phase of the flushing medium to the reactor can be stopped while the liquid phase of the flushing medium continues. The duration of the additional liquid flush is at least 30 minutes, or at least 1 hour, or at least 2 hours, or at least 3 hours, or at least 4 hours, or at least 5 hours, at least 6 hours, or less than 24 hours, or less than 2 days, or less than 3 days, or less than 4 days, or less than 5 days, or less than 6 days, or less than 1 week, or more.

[0054] In some embodiments, the oxygen content in the flushing medium (e.g., the gas phase of the first flushing medium) is selected based on the amount of hydrogenation catalyst 38 in reactor 12. In some embodiments, the first flushing medium has an oxygen content of 0.1×10 -3 ~100×10 -3 (mol / g / hr). In some embodiments, the O2 / cat / hr flux ratio is at least 0.1 x 10 -3 (mol / g / hr), e.g., at least 0.5 × 10 -3 (mol / g / hr), or at least 1 × 10 -3 (mol / g / hr). In some embodiments, the O2 / cat / hr flux ratio is 100×10 -3(mol / g / hr) or less, e.g., 50×10 -3 (mol / g / hr) less than 10 × 10 -3 (mol / g / hr) or less than 5 x 10 -3 (mol / g / hr).

[0055] In some embodiments, the water content in the first flushing medium is based on the amount of hydrogenation catalyst 38 in reactor 12. In some embodiments, the first flushing medium comprises a water-to-catalyst flux ratio (HO / cat / hr) of 1 to 100 (g / g / hr). In some embodiments, the HO / cat / hr ratio of the first flushing medium is at least 1 (g / g / hr), e.g., at least 2 (g / g / hr), at least 5 (g / g / hr), or at least 10 (g / g / hr). In some embodiments, the HO / cat / hr ratio of the first flushing medium is less than 100 (g / g / hr), e.g., less than 50 (g / g / hr), less than 20 (g / g / hr), or less than 10 (g / g / hr).

[0056] In some embodiments, the second flushing medium is 0.1×10 -3 ~100×10 -3 (mols / w / hr). In some embodiments, the N / cat / hr flux ratio is at least 0.1 x 10 -3 (mol / g / hr), e.g., at least 0.5 × 10 -3 (mol / g / hr), or at least 1 × 10 -3 (mol / g / hr). In some embodiments, the N / cat / hr flux ratio is 100×10 -3 (mol / g / hr) or less, e.g., 50×10 -3 (mol / g / hr) less than 10 × 10 -3 (mol / g / hr) or less than 5 x 10 -3 (mol / g / hr).

[0057] In some embodiments, the water content in the second flushing medium is based on the amount of hydrogenation catalyst 38 in reactor 12. In some embodiments, the second flushing medium comprises a water-to-catalyst flux ratio (HO / cat / hr) of 1 to 100 (g / g / hr). In some embodiments, the HO / cat / hr ratio of the second flushing medium is at least 1 (g / g / hr), e.g., at least 2 (g / g / hr), at least 5 (g / g / hr), or at least 10 (g / g / hr). In some embodiments, the HO / cat / hr ratio of the second flushing medium is less than 100 (g / g / hr), e.g., less than 50 (g / g / hr), less than 20 (g / g / hr), or less than 10 (g / g / hr).

[0058] The nitrogen content in the gas phase of the second flushing medium can be selected to provide a desired inert atmosphere, as opposed to the oxidizing atmosphere provided by the gas phase of the first flushing medium (e.g., at least 90% by volume air). In some embodiments, the second flushing medium comprises a gas phase comprising at least 99% by volume nitrogen, measured at 25° C. and 1 atmosphere pressure.

[0059] The inclusion of water in the flushing medium provides several advantages. First, water acts as a heat sink for the flushing medium, improving temperature control of the reactor 12 compared to a flushing medium composed solely of gas. Improved heat control avoids the development of hot spots that can burn off catalyst supports, such as carbon. Water is also a polar solvent, which can facilitate the removal of certain impurities, such as ionic salts and other polar moieties. Furthermore, the inclusion of water in the flushing medium helps keep the hydrogenation catalyst 38 moist during regeneration. A flushing medium composed solely of gas can dry out the catalyst and cause cracks in the fixed bed, leading to more frequent replacement.

[0060] In some embodiments, the flushing medium is substantially free or completely free of hydrogen peroxide. As used herein, the term "substantially free of hydrogen peroxide" refers to less than 1%, or less than 0.5%, or less than 0.1%, or less than 0.05% hydrogen peroxide. In some embodiments, the flushing medium is substantially free or completely free of hydrogen peroxide before entering reactor 12.

[0061] In some embodiments, one or more regeneration cycles are used to generate a regenerated hydrogenation catalyst. For example, the method may include subjecting an aged hydrogenation catalyst to one, two, three, four, or more regeneration cycles as described herein, and the conditions (e.g., temperature, pressure, and duration) of one regeneration cycle may be controlled independently from the corresponding conditions of another regeneration cycle. For example, a first regeneration cycle may be performed at a different temperature or pressure, or for a different duration, than a second regeneration cycle.

[0062] Unlike typical catalyst regeneration processes that operate under gas-phase conditions at temperatures above 200°C (e.g., decoking and desulfurization reactions) or utilize oxidants that degrade the physical structure of the catalyst over time (e.g., HO-based regeneration), the present disclosure provides a method for regenerating hydrogenation catalyst 38 using a flushing medium that operates under less severe conditions (e.g., temperatures below 200°C). As reported in co-pending U.S. patent application Ser. No. 17 / 891,093, a flushing medium comprising water, oxygen, and an inert / diluent gas at a specified regeneration pressure and temperature is effective in removing impurities from the hydrogenation catalyst and restoring catalytic activity by maintaining the structural integrity of the catalyst (e.g., total surface, pore size, pore volume). Surprisingly and unexpectedly, as shown in the present disclosure, regeneration efficiency can be further improved by switching the gas phase of the flushing medium from air (a higher oxygen or oxidizing atmosphere) to nitrogen (a lower oxygen or inert atmosphere), because more impurities (e.g., sulfur-containing impurities) can be removed from the depleted catalyst during the nitrogen treatment duration. By accommodating atmosphere switching between different gas phases, systems such as those described herein can regenerate depleted hydrogenation catalysts more efficiently at reduced cost. For example, the nitrogen treatment duration can be adjusted according to the recirculation rate of the flushing medium to reduce water consumption and improve impurity (e.g., sulfur-containing impurities) removal.

[0063] Furthermore, the present system allows for a "pulse" regeneration process with multiple regeneration cycles, each cycle switching between an oxidizing atmosphere (e.g., a pulse of air treatment) and an inert atmosphere (e.g., a pulse of nitrogen treatment), thus providing greater flexibility and efficiency in controlling the regeneration process. Even more surprisingly, the present "pulse" regeneration system can be more effective at removing sulfur from depleted catalysts than systems that do not utilize air / nitrogen switching, where the feedstock typically contains higher sulfur-containing impurities. Thus, the present system has unexpected superior capabilities over previous systems for regenerating catalysts used in the hydrogenation of feedstocks with high sulfur content.

[0064] In another aspect, the present disclosure provides a method for producing a regenerated hydrogenation catalyst from a depleted hydrogenation catalyst, the method comprising: catalytically reacting a feedstream having at least one sulfur-containing impurity in the presence of a hydrogenation catalyst to produce an aged hydrogenation catalyst, the aged hydrogenation catalyst comprising an amount of sulfur derived from the at least one sulfur-containing impurity of the feedstream; subjecting the depleted hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flushing medium comprising a gas phase comprising liquid water and oxygen, measured at 25°C and 1 atmosphere for an air treatment duration, to produce an air-treated catalyst; and (b) contacting the air-treated catalyst with a second flushing medium comprising liquid water and a gas phase containing at least 90% by volume of nitrogen, measured at 25°C and 1 atmosphere, for the duration of the nitrogen treatment to produce a nitrogen-treated catalyst; wherein the amount of sulfur in the nitrogen-treated hydrogenation catalyst is reduced compared to an aged hydrogenation catalyst.

[0065] The aged hydrogenation catalyst can be, for example, a hydrogenation catalyst that has been exposed to a feed solution under the specified hydrogenation conditions (e.g., temperature, pressure, feed concentration) described herein for a period of time (e.g., at least 1 day, at least 2 days, at least 3 days, at least 4 days, at least 5 days, at least 6 days, at least 1 week, at least 2 weeks, at least 3 weeks, at least 1 month, at least 6 months, at least 1 year). The aged hydrogenation catalyst can be generated by exposing a fresh catalyst that has never been exposed to a feed solution to the specified hydrogenation conditions, or by exposing a freshly regenerated catalyst to the specified hydrogenation conditions.

[0066] Suitable first and second flushing media include those described above. In some embodiments, the gas phase of the first flushing medium contains about 0.1% to about 30% by volume of oxygen. The gas phase of the first flushing medium may further contain an inert gas, such as nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide, or a combination thereof. In some embodiments, the gas phase of the first flushing medium contains at least 90% by volume of air. In some embodiments, the gas phase of the second flushing medium contains at least 99% by volume of nitrogen. In some embodiments, the gas phase of the second flushing medium is essentially free of oxygen. In some embodiments, the method includes subjecting the nitrogen-treated catalyst to successive sets of regeneration cycles (a) and (b), each with a respective treatment duration, to produce a regenerated hydrogenation catalyst. For example, the method may include subjecting the nitrogen-treated catalyst to one, two, three, four, or more successive regeneration cycles as described herein. Advantageously, the conditions (e.g., temperature, pressure, and duration) of each regeneration cycle may be independently controlled. Additionally, the air treatment duration and nitrogen treatment duration in each regeneration cycle may be adjusted to improve regeneration efficiency based on the sulfur content in the feed, the amount of sulfur in the depleted catalyst, and the recirculation rate of the flushing medium.

[0067] In some embodiments, the air treatment duration in one or more of the regeneration cycles is at least 30 minutes, for example, about 2 to 4 hours.

[0068] In some embodiments, the duration of nitrogen treatment in one or more of the regeneration cycles is at least 30 minutes, or at least 4 hours, for example, about 12 to 24 hours.

[0069] In some embodiments, the amount of sulfur in the nitrogen-treated or regenerated hydrogenation catalyst is reduced by at least 5% compared to the aged hydrogenation catalyst, which may be at least a 10% reduction, at least a 15% reduction, at least a 20% reduction, at least a 30% reduction, at least a 40% reduction, at least a 50% reduction, or at least a 60% reduction compared to the sulfur content of the aged hydrogenation catalyst.

[0070] In some embodiments, the air treatment duration is at least 30 minutes, the nitrogen treatment duration is at least 4 hours, and the amount of sulfur in the regenerated hydrogenation catalyst is reduced by at least 5% compared to the aged hydrogenation catalyst. In some embodiments, multiple regeneration cycles (e.g., a total of 2, 3, 4, 5, 6, 7, 8, 9, or 10 cycles) are performed in the method, at least one of the cycles includes an air treatment duration of at least 30 minutes and a nitrogen treatment duration of at least 4 hours, and the amount of sulfur in the regenerated hydrogenation catalyst is reduced by at least 5% compared to the aged hydrogenation catalyst.

[0071] In some embodiments, the regeneration cycle is performed at a temperature of about 70° C. to about 120° C. In some embodiments, multiple regeneration cycles (e.g., a total of 2, 3, 4, 5, 6, 7, 8, 9, or 10 cycles) are performed in the method, and at least one of the multiple regeneration cycles is performed at a temperature of about 70° C. to about 120° C.

[0072] In some embodiments, the regeneration cycle is performed at a pressure of about 50 psig to about 200 psig. In some embodiments, multiple regeneration cycles (e.g., a total of 2, 3, 4, 5, 6, 7, 8, 9, or 10 cycles) are performed in the method, and at least one of the multiple regeneration cycles is performed at a pressure of about 50 psig to about 200 psig.

[0073] The method can be particularly effective in regenerating catalysts used in the hydrogenation of feedstocks having higher than normal levels of sulfur-containing impurities. In some embodiments, the feedstream has a sulfur content of at least 0.1 ppm, including, but not limited to, at least 0.2 ppm, at least 0.3 ppm, at least 0.4 ppm, at least 0.5 ppm, at least 1.0 ppm, at least 2.0 ppm, at least 5.0 ppm, at least 10.0 ppm, at least 20 ppm, at least 30 ppm, at least 40 ppm, at least 50 ppm, and at least 100 ppm. In some embodiments, the feedstream has a sulfur content of at least 0.5 ppm, e.g., at least 1.0 ppm, or at least 5 ppm.

[0074] In some embodiments, the amount of sulfur removed from the catalyst is measured to monitor the progress of the regeneration process. Based on this information, conditions (e.g., temperature, pressure, air treatment duration, and nitrogen treatment duration) for further regeneration cycles can be adjusted to improve efficiency. In some embodiments, the method further includes measuring a first sulfur content of the first flushing medium after contacting the catalyst in (a) and / or measuring a second sulfur content of the second flushing medium after contacting the catalyst in (b); and subjecting the nitrogen-treated catalyst to successive sets of operations (a) and (b), each with a respective treatment duration. The sulfur content in the flushing medium can be measured by any suitable analytical method. For example, the sulfur content can be measured by measuring the conductivity and / or pH of the first or second flushing medium, or by inductively coupled plasma (ICP) methods.

[0075] In some embodiments, the regenerated hydrogenation catalyst exhibits excellent retention of catalytic activity after regeneration. As used herein, the terms "retain," "retaining," or "retention" with respect to a reference value include both fractional and incremental increases relative to the reference value. For example, a specified parameter (e.g., the conversion of the regenerated catalyst) may be retained less than or greater than 100% of the reference parameter (e.g., the conversion of the fresh catalyst or the depleted catalyst from which the regenerated catalyst is generated).

[0076] Typically, an aged catalyst has a lower catalytic activity (e.g., as measured by a conversion value) than a fresh catalyst. The catalytic activity of an aged catalyst can be improved by the regeneration methods described herein to a level close to that of the fresh (or freshly regenerated) catalyst from which the aged catalyst was generated. That is, the regeneration methods described herein can be used to restore the catalytic activity of an aged catalyst to the level of a fresh (or freshly regenerated) catalyst. The conversion value (as a measure of catalytic activity) described herein of the regenerated catalyst, or the conversion value of the aged catalyst from which the regenerated catalyst is generated, may be compared to the conversion value of the fresh catalyst. For example, the conversion value of the aged catalyst may be about 50%, about 60%, about 70%, about 80%, or about 90% of the conversion value of the fresh catalyst. For example, the regenerated catalyst may have a conversion value of about 70%, about 80%, about 90%, about 95%, about 99%, about 100%, or about 110% of the conversion value of a fresh catalyst. In some embodiments, the regenerated catalyst has a conversion value that is at least 5%, at least 10%, at least 20%, at least 50%, at least 70%, at least 90%, or at least 100% higher than the conversion value of an aged catalyst. In some embodiments, the regenerated catalyst retains at least 100%, at least 105%, at least 110%, at least 120%, at least 150%, at least 170%, at least 190%, or at least 200% of the conversion value of the aged catalyst. As an example, a fresh catalyst may have a conversion value of 0.96, and an aged catalyst may have a conversion value of 0.70 (or 73% of the fresh catalyst). After regeneration, the regenerated catalyst has a conversion value of 0.94 (or 98% of the fresh catalyst). In this example, the regenerated catalyst retains 134% of the conversion of the aged catalyst (or the regenerated catalyst has a conversion value 34% higher than the aged catalyst).

[0077] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art relevant to the present invention. All definitions defined and used herein should be understood to control dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms. As used herein, the terms "include" and "including" have the same meaning as the terms "comprise" and "comprising." The terms "comprise" and "comprising" should be interpreted as "open-ended" transitional terms that allow for the inclusion of additional elements in addition to those recited in the claims. The terms "consist" and "consisting of" should be interpreted as "open-ended" transitional terms that do not allow for the inclusion of additional elements other than those recited in the claims. The term "consisting essentially of" should be interpreted as partially restricted, allowing for the inclusion of only additional elements that do not fundamentally alter the nature of the claimed subject matter. As used herein, the singular forms "a," "an," and "the" include plural embodiments unless the context clearly dictates otherwise. The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes at least the degree of error associated with measurement of the particular quantity). The modifier "about" should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. For example, the phrase "about 2 to about 4" also discloses a range of "2 to 4." The term "about" may refer to plus or minus 10% of the stated number. For example, "about 10%" may refer to a range of 9% to 11%, and "about 1" may mean 0.9 to 1.1.

[0078] While the invention has been described in terms of one or more preferred embodiments, it should be understood that many equivalents, alternatives, variations, and modifications aside from those expressly described are possible and are within the scope of the invention. [Example]

[0079] [Example 1] A regeneration test of impurity-laden hydrogenation catalysts was conducted using a flushing medium containing a liquid phase containing water and a gas phase containing nitrogen and oxygen. This process was called "wet oxidation regeneration" (WAOR). A fresh Ru / C hydrogenation catalyst was deactivated with glucose monohydrate or corn syrup feed to be hydrogenated. The hydrogenation reaction was run continuously for several days until the hydrogenation catalyst was deactivated. WAOR experiments were conducted on the deactivated hydrogenation catalyst. Standard WAOR process conditions were as follows: 100% air, inlet temperature 100-110°C, reactor pressure 100 psig, and water and air flow for 24 hours. After 24 hours, the water flow was continued, but the system was purged with N2 to remove any traces of oxygen before hydrogen was introduced to reduce the catalyst. In various studies conducted herein, oxygen levels of 1% (e.g., 5% air, 95% nitrogen) to 20% (e.g., 100% air) in the gas phase of the flushing medium were used with similar results. Nitrogen as used herein was supplied as a high purity gas (eg, 99% or greater).

[0080] Standard WAOR regeneration can be useful for restoring catalyst activity with the majority of corn syrups in the processes tested, but even extended periods using air were insufficient for catalyst restoration when a high-sulfur corn syrup feed was used. Sulfur impurities deposited on the catalyst can be removed during the regeneration process, as measured by the amount of sulfur in the effluent liquid phase (water) of the flushing medium (e.g., by weight or weight percent relative to the sulfur in the feed). Surprisingly, in some experiments, it was observed that bulk sulfur removal occurred during the WAOR process only after switching to N purging, with minimal or no sulfur removal occurring under airflow. Furthermore, comparison of results from WAOR experiments with different airflow durations (e.g., 24 hours vs. 4 hours) showed that the sulfur content in the effluent water peaked at approximately the same time after switching to N 2 , regardless of airflow duration (e.g., 2–6 hours after switching to N 2 after 4 or 24 hours of airflow). More importantly, in these experiments with different airflow durations, similar amounts of sulfur (measured by weight % relative to sulfur in the feed) were removed (17% removed with 24 hours of airflow vs. 14% removed with 4 hours of airflow). These results suggest that significant amounts of sulfur are removed from the deactivated catalyst after the N2 flow is introduced but not during the airflow.

[0081] Further regeneration studies were conducted on the 2 wt. % Ru / C catalyst after approximately 50 days of reaction with the feed stream. During the regeneration step, samples of the reactor effluent were taken after nitrogen was introduced to flush oxygen from the reactor and during the wet reduction. While no sulfur was detected during regeneration under air flow, significant levels were observed after the atmosphere in the reactor was switched to N2 and then H2 (Figure 2). These results indicated that changing the reactor atmosphere can affect sulfur removal from the catalyst.

[0082] Similar results were observed from regeneration in an additional study in which the sulfur content of the effluent was monitored every four hours (Table 1). The highest sulfur content observed during the air flow was at the very end with air in the system (6.1 ppm sulfur after 24 hours). However, the first sample after switching to N2 showed a sulfur content of 24 ppm (Table 1), demonstrating a significant increase in sulfur removal after switching from air to N2. This result again indicated that sulfur removal was related to the change in reactor atmosphere.

[0083] [Table 2]

[0084] In a further study, instead of passing air through the reactor during the 24-hour regeneration, air was supplied for only 4 hours. The first ICP sample was collected only after the air flow had been stopped for several hours, but the sulfur level in the effluent had already passed its peak and appeared to be dropping. These data indicate that the sulfur content peaked after the switch from air to N2 (Figure 3).

[0085] With a typical corn syrup feed and standard WAOR regeneration procedure, the catalyst can have a cycle time of approximately 50 to 70 days, after which it must be regenerated to maintain sufficient conversion of glucose to sorbitol. However, when corn syrup with higher-than-normal levels of sulfur (e.g., 0.5 ppm or higher) was used as the feed, a three- to four-fold higher catalyst deactivation rate was observed. The high loading of sulfur impurities on the catalyst necessitated earlier WAOR than normal. With these feeds, the first regeneration was required after only 30 days (Figure 4, regeneration at approximately 380 days). Even after this regeneration, the observed catalytic activity was low, requiring a second regeneration after only 10 days (Figure 4, regeneration at approximately 390 days). Significant levels of sulfur were observed in the effluent from these regenerations.

[0086] Based on the observation that sulfur was primarily removed from the catalyst after switching from air flow to nitrogen and the hypothesis that the short cycle time at 380 days on stream was due to insufficient sulfur removal from the catalyst, a new "pulse" regeneration procedure was developed. The "pulse" procedure used the same reactor temperature, pressure, and gas and liquid flow rates, but was designed to switch from air to nitrogen after only 12 hours. After a 12-hour nitrogen purge, air was reintroduced. After another 12 hours of air flow, nitrogen was introduced, followed by one final cycle of 12 hours of air / 12 hours of nitrogen. Samples of the aqueous effluent were collected periodically and analyzed for pH, conductivity, and sulfur content (Figure 5). Consistent with previous observations, sulfur levels did not spike until after the atmosphere was switched to N2. Concurrent with this sudden increase in sulfur levels, conductivity spiked to 350 μS / cm and pH dropped from approximately 3.7 to 3.2. These effects are consistent with sulfur being removed from the catalyst as acidic substances (e.g., H2SO4). After switching back to air, the sulfur level and conductivity decreased, while the pH increased. A second N2 purge again showed an increase in sulfur content and conductivity, indicating that this second air / N2 cycle removed additional sulfur from the catalyst, although the amount was less than that of the first cycle. A third cycle removed a significant amount of additional sulfur from the catalyst, although the amount was less than that of the first and second cycles.

[0087] After this pulse regeneration, the feed was again introduced into the post-reduction reactor. This feed also contained higher levels of sulfur. Surprisingly, catalyst activity returned to start-of-process levels, indicating that the pulse regeneration process was more effective at removing high levels of sulfur poisoning from the catalyst than the previous standard WAOR regeneration process. The catalyst was then continuously run for 19 days, at which point further regeneration was required due to high levels of sulfur poisoning in the feed. As with the previous regeneration process, sulfur levels rose sharply after switching to N2, which was also consistent with the conductivity data (Figure 6). Due to the ease of measuring conductivity, the rapidity with which samples could be analyzed, and the possibility of online measurement, the conductivity data was used as a reliable marker of sulfur content. This regeneration process showed similar conductivity levels in the third pulse as in the second pulse, so a fourth pulse was performed.

[0088] The pulse regeneration procedure was further developed. At a different plant, an air purge of only 30 minutes was attempted, dropping it below 12 hours. This change appeared to significantly reduce the regeneration time. These short pulses were still effective in removing sulfur from the catalyst (Figure 7). Each of the four pulses showed a similar increase in conductivity and sulfur content in the effluent, suggesting insufficient sulfur oxidation during each pulse. The pulse duration in these processes could be further engineered to maximize sulfur removal in a short period of time.

[0089] In summary, a pulse regeneration process using air / N2 atmosphere switching was performed on a hydrogenation catalyst, and the performance of the catalyst regenerated by this method returned to activity very close to that at the start of the process, compared to the activity of a catalyst regenerated by a previous non-pulse regeneration. A significant amount of sulfur was removed during the nitrogen treatment, and high levels of sulfur could be removed with multiple regeneration cycles (pulses). For example, sulfur levels could remain high in the effluent of the second and third regeneration cycles (pulses). The conductivity and pH of the effluent were used to track the amount of sulfur removed from the catalyst. In some tests, the pulse regeneration process was performed using 30 minutes of air flow and 23.5 hours of nitrogen flow in each pulse, and it remained effective in removing significant amounts of sulfur from the catalyst.

[0090] For completeness, various aspects of the invention are set out in the following numbered clauses:

[0091] Clause 1 1. A method for hydrogenating biomass, comprising: Water and oxygenated hydrocarbons (C 2+ O 1+ catalytically reacting a feed stream comprising: (I) a first hydrogenation product stream and (II) a depleted hydrogenation catalyst with hydrogen in the presence of a hydrogenation catalyst for a hydrogenation duration to produce a first hydrogenation product stream and a depleted hydrogenation catalyst; subjecting the depleted hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flushing medium comprising a gas phase comprising liquid water and oxygen, measured at 25°C and 1 atmosphere for an air treatment duration, to produce an air-treated catalyst; and (b) contacting the air-treated catalyst with a second flushing medium comprising a gaseous phase containing liquid water and at least 90% by volume of nitrogen, measured at 25°C and 1 atmosphere for the duration of the nitrogen treatment, to produce a regenerated hydrogenation catalyst. producing a regenerated hydrogenation catalyst, comprising: catalytically reacting the feed stream with hydrogen in the presence of a regenerated hydrogenation catalyst to further produce a second hydrogenated product stream; A method comprising:

[0092] Clause 2 2. The method according to clause 1, wherein the duration of the air treatment is at least 30 minutes.

[0093] Clause 3 3. The method according to clause 1 or 2, wherein the duration of the nitrogen treatment is at least 30 minutes.

[0094] Clause 4 4. The method of any one of clauses 1 to 3, wherein the regeneration cycle is carried out at about 70°C to about 120°C.

[0095] Clause 5 5. The method of claim 1, wherein the regeneration cycle is carried out at a pressure of about 50 psig to about 200 psig.

[0096] Clause 6 The first flushing medium is 0.1×10 -3 ~100×10 -3 6. The method of any one of clauses 1 to 5, comprising an oxygen to catalyst flux ratio (O2 / cat / hr) of (mols / g / hr).

[0097] Clause 7 7. The method of any one of clauses 1 to 6, wherein the first flushing medium and / or the second flushing medium comprises a water to catalyst flux ratio (H2O / cat / hr) of 1 to 100 (g / g / hr).

[0098] Article 8 The second flushing medium is 0.1 x 10 -3 ~100×10 -3 8. The method of any one of clauses 1 to 7, comprising a nitrogen to catalyst flux ratio (N2 / cat / hr) of (mols / g / hr).

[0099] Article 9 9. The method of any one of clauses 1 to 8, wherein the gas phase of the first flushing medium comprises about 0.1% to about 30% by volume of oxygen.

[0100] Article 10 10. The method of any one of clauses 1 to 9, wherein the gaseous phase of the first flushing medium further comprises an inert gas selected from the group consisting of nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide, and combinations thereof.

[0101] Article 11 11. The method of any one of clauses 1 to 10, wherein the gas phase of the first flushing medium comprises at least 90% by volume of air.

[0102] Article 12 12. The method of any one of clauses 1 to 11, wherein the gas phase of the second flushing medium comprises at least 99% by volume of nitrogen.

[0103] Article 13 13. The method of any one of clauses 1 to 12, wherein the gaseous phase of the second flushing medium is essentially free of oxygen.

[0104] Article 14 14. The method of any one of clauses 1 to 13, wherein the oxygenated hydrocarbon is a saccharide.

[0105] Article 15 15. The process of any one of clauses 1 to 14, wherein the hydrogenation catalyst comprises a support and an active metal.

[0106] Article 16 16. The process of clause 15, wherein the hydrogenation catalyst is ruthenium on carbon (Ru / C).

[0107] Article 17 1. A method for producing a regenerated hydrogenation catalyst from a depleted hydrogenation catalyst, the method comprising: catalytically reacting a feedstream having at least one sulfur-containing impurity in the presence of a hydrogenation catalyst to produce an aged hydrogenation catalyst, the aged hydrogenation catalyst comprising an amount of sulfur derived from the at least one sulfur-containing impurity of the feedstream; subjecting the depleted hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flushing medium comprising a gas phase comprising liquid water and oxygen, measured at 25°C and 1 atmosphere for an air treatment duration, to produce an air-treated catalyst; and (b) contacting the air-treated catalyst with a second flushing medium comprising liquid water and a gaseous phase containing at least 90% by volume of nitrogen, measured at 25°C and 1 atmosphere for the duration of the nitrogen treatment, to produce a nitrogen-treated catalyst. producing a regenerated hydrogenation catalyst, wherein the amount of sulfur in the nitrogen-treated hydrogenation catalyst is reduced compared to an aged hydrogenation catalyst.

[0108] Article 18 18. The method of claim 17, comprising subjecting the nitrogen-treated catalyst to successive sets of regeneration cycles of operations (a) and (b), each with a respective treatment duration, to produce a regenerated hydrogenation catalyst.

[0109] Article 19 19. The method according to clause 17 or 18, wherein the duration of the air treatment is at least 30 minutes.

[0110] Article 20 20. The method of any one of clauses 17 to 19, wherein the nitrogen treatment duration is at least 30 minutes.

[0111] Article 21 21. The method of any one of clauses 17 to 20, wherein the duration of the air treatment is at least 30 minutes and the duration of the nitrogen treatment is at least 4 hours, and the amount of sulfur in the regenerated hydrogenation catalyst is reduced by at least 5% compared to the aged hydrogenation catalyst.

[0112] Article 22 22. The method of any one of clauses 17 to 21, wherein the regeneration cycle is carried out at a temperature of from about 70°C to about 120°C.

[0113] Article 23 23. The method of any one of clauses 17 to 22, wherein the regeneration cycle is conducted at a pressure of about 50 psig to about 200 psig.

[0114] Article 24 24. The method of any one of clauses 17 to 23, wherein the feed stream has a sulfur content of at least 0.1 ppm.

[0115] Article 25 25. The method of any one of clauses 17 to 24, wherein the gas phase of the first flushing medium comprises about 0.1% to about 30% by volume of oxygen.

[0116] Article 26 26. The method of any one of clauses 17 to 25, wherein the gaseous phase of the first flushing medium further comprises an inert gas selected from the group consisting of nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide, and combinations thereof.

[0117] Article 27 27. The method of any one of clauses 17 to 26, wherein the gas phase of the first flushing medium comprises at least 90% by volume of air.

[0118] Article 28 28. The method of any one of clauses 17 to 27, wherein the gas phase of the second flushing medium comprises at least 99% by volume of nitrogen.

[0119] Article 29 29. The method of any one of clauses 17 to 28, wherein the gaseous phase of the second flushing medium is essentially free of oxygen. [Explanation of symbols]

[0120] 10. Reactor System 12 Reactor 14 Raw material injection port 16 Raw material conduit 18 Pump 20 Raw material sources 22 Heat exchanger 24 valves 26 Hydrogen inlet 28 Hydrogen Pipe 30 Gas transport equipment 32 Hydrogen Source 34 Heat exchanger 36 Valves 38 Hydrogenation catalyst 50 Reactor outlet 52 Product Conduit 54 Separator 56 Heat exchanger 58 Hydrogen recirculation conduit 60 Product outlet 62 Second Separator 64 Conduit 66 Pump 68 Heat exchanger 70 valves 72 Recirculation conduit 74 Product Conduit 76 Downstream Processing Unit 78 Gas Phase Inlet 80 Gas Phase Source 82 Gas phase conduit 84 Fluid transport device 86 Heat exchanger 88 Valve 90 Liquid phase inlet 92 Liquid Phase Source 94 Liquid phase conduit 96 Pump 98 Heat exchanger 100 valves 102 Valve

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