A process for wet air oxidation regeneration of a biomass hydrogenation catalyst using switching between oxygen and nitrogen atmospheres; biomass hydrogenation process comprising the same

Abstract

The present disclosure provides systems and methods for generating a regenerated hydrogenation catalyst for hydrogenating a biomass feedstock. The process can include a regeneration cycle in which the contaminated hydrogenation catalyst is contacted with (a) a first purge medium comprising water and a gas phase comprising oxygen and (b) a second purge medium comprising water and a gas phase comprising 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 contaminated catalysts.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 480,607, filed on January 19, 2023, the contents of which are hereby incorporated by reference in their entirety. background

[0002] Biomass is a potential renewable alternative to petroleum-based fuels, chemicals, and other products. However, developing efficient, economical, and environmentally friendly technologies to convert biomass into useful products remains challenging.

[0003] Bioreforming is a promising method that provides liquid fuels and chemicals derived from cellulose, hemicellulose, and lignin present in plant cell walls. For example, cellulose and hemicellulose can be used as feedstocks for a variety of bioreforming processes, including aqueous phase reforming (APR) and hydrodeoxygenation (HDO), a catalytic reforming process that, when combined 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 (to Cortright et al., entitled “Low-Temperature Hydrocarbon Production from Oxygenated Hydrocarbons”); and U.S. Pat. Nos. 7,767,867 and 7,989,664 and U.S. Application 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 Biomass”); International Patent Application Publication No. WO 2008 / 109877 (to Cortright and Blommel, entitled “Synthesis of Liquid Fuels and Chemicals from Oxygenated Hydrocarbons”); 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 the biomass feedstock to increase its thermal stability before use as a feedstock for APR and / or HDO. Sugars are susceptible to thermal degradation at temperatures compatible with APR and / or HDO, leading to byproduct formation, catalyst contamination, and ultimately, shortened catalyst regeneration times. This problem is avoided by reacting sugars with hydrogen to form more thermally stable polyols or sugar alcohols.

[0005] Biomass raw materials include impurities, such as sulfur-containing parts, which poison hydrogenation catalysts over time. The poisoning of the catalyst results in lower conversion rates and yields of polyols and sugar alcohol products. Therefore, most industrial applications involve batch processes or semi-continuous processes, which involve replacing spent catalysts with fresh catalysts or regenerating existing catalysts to improve conversion rates. Frequently replacing hydrogenation catalysts is time-consuming, expensive, and may cause production shutdowns. It is noteworthy that when the raw materials include elevated sulfur-containing impurities, poisoning or deactivation of the hydrogenation catalyst can worsen.

[0006] Current methods for regenerating hydrogenation catalysts involve using multiple hydrogen peroxide washes to remove impurities from spent hydrogenation catalysts. However, hydrogen peroxide destroys the physical strength of the catalyst over time, reducing its overall surface area and ultimately reducing its catalytic activity. A need remains for more efficient, less disruptive regeneration systems and methods for restoring the catalytic capacity of hydrogenation catalysts under industrial production conditions. SUMMARY OF THE INVENTION

[0007] This paper describes a reactor system and method for regenerating a hydrogenation catalyst for use in hydrogenating feedstock solutions, such as water-soluble sugars derived from biomass and / or unsaturated hydrocarbon streams. The reactor system and method provided provide unique features and advantages that are superior to existing regeneration technologies. This is an improvement over current technologies for regenerating catalytic activity, which, such as methods based on hydrogen peroxide, have a tendency to reduce the surface area and pore structure of the catalyst over time. In addition, hydrogen peroxide presents a storage challenge on a commercial scale. The regenerative oxidant provided herein is cheaper than hydrogen peroxide and can be stored on a commercial scale using existing technology.

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

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

[0010] In some embodiments, the method of the present invention comprises subjecting the nitrogen-treated catalyst to a set of consecutive regeneration cycles of operation (a) and operation (b), each operation having a corresponding treatment duration, to produce a regenerated hydrogenation catalyst. For example, the conditions (such as temperature, pressure, and duration) 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 process of the present invention may include ruthenium supported on carbon (Ru / C). BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 An exemplary reactor system according to some embodiments of the present disclosure is shown.

[0013] Figure 2 Representative results are shown for sulfur content analysis of effluent samples from a wet air oxidation regeneration (WAOR) process on a 2 wt% Ru / C catalyst. Six samples were collected while air was flowing through the reactor (BDL = below detection limit), one sample was collected during an N2 purge, and one final sample was collected during the wet reduction.

[0014] Figure 3 A comparison of four regeneration processes on a Ru / C catalyst is shown (Regeneration 1 - Regeneration 4). Regenerations 1 - 3 all ran with air for 24 hours, while Regeneration 4 ran with air for 4 hours.

[0015] Figure 4The performance of the Ru / C catalyst as characterized by conversion and hydrogenation reactor inlet temperature is shown. Regeneration is marked with a vertical line, and the change in corn syrup batch is shown with a gray dashed line.

[0016] Figure 5 Shown are the sulfur content, conductivity, and pH in the effluent from a "pulsed" WAOR process in which the reactor switches between air and N2 flow every 12 hours.

[0017] Figure 6 Shown are the sulfur content and conductivity of the effluent from the second pulse regeneration process on the Ru / C catalyst.

[0018] Figure 7 Sulfur content and conductivity data are shown for a pulse regeneration process using a 30 minute air flow (pulse) on a Ru / C catalyst. Detailed Description of the Invention

[0019] This paper describes a reactor system and method for regenerating a hydrogenation catalyst for hydrogenating a feed solution, such as a water-soluble sugar derived from biomass and / or an unsaturated hydrocarbon stream. The reactor system and method provided provide unique features and advantages that are superior to existing regeneration technologies. In co-pending U.S. patent application Ser. No. 17 / 891,093, a wet air oxidation regeneration system is disclosed, which provides mild reaction conditions that can effectively remove impurities to restore hydrogenation catalytic activity while additionally maintaining the structural integrity (e.g., surface area, pore volume) of the catalyst, the contents of which are incorporated herein by reference in their entirety. The time period during which the structural integrity and / or catalytic activity of the catalyst is maintained for an extended period improves operating economy by reducing the number of times the catalyst needs to be replaced over time and / or reducing the frequency of required regeneration operations. The regeneration system of the present invention retains the advantages of the system disclosed in US 17 / 891,093. Notably, the system of the present invention can accommodate atmosphere switching (e.g., from air to nitrogen) during the regeneration process and provides more efficient regeneration results with the added advantage of effectively regenerating catalysts used to hydrogenate feedstocks having high levels of sulfur-containing impurities.

[0020] In one aspect, the present disclosure provides a method for hydrogenating biomass, the method comprising: Containing water and oxygen-containing hydrocarbon (C 2+ O1 + ) with hydrogen in the presence of a hydrogenation catalyst for a hydrogenation duration to produce a first hydrogenated product stream and contaminated hydrogenation catalyst; The contaminated hydrogenation catalyst is subjected to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flush medium for an air treatment duration to produce an air-treated catalyst, wherein the first flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a gas phase comprising oxygen, and (b) contacting the air-treated catalyst with a second flush medium for a nitrogen treatment duration to produce a regenerated hydrogenation catalyst, wherein the second flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a vapor phase comprising at least 90% by volume nitrogen; and The feed stream is catalytically reacted with hydrogen in the presence of the regenerated hydrogenation catalyst to further produce a second hydrogenated product stream.

[0021] The method of the present invention can be carried out in a reactor system. Figure 1 , a representative reactor system 10 is illustrated according to some embodiments of the present disclosure. Although the principles disclosed herein can be advantageously implemented on the illustrated reactor system 10, it is possible for some embodiments to use other reactor system architectures. 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 can be configured in the feed conduit 16 to transport a feed solution from a feed source 20, such as a reservoir or an upstream processing unit, to the reactor 12. The feed conduit 16 can include a heat exchanger 22 for controlling the temperature of the feed solution and a valve 24 for controlling the flow of the feed solution to the reactor 12.

[0022] In some embodiments, a suitable feedstock solution includes water-soluble sugars derived from biomass, although other feedstocks may 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) as well as metabolic waste products of microorganisms and animals. Common sources of biomass include: (1) agricultural wastes such as corn stover, straw, seed hulls, sugarcane residues, bagasse, nut shells, and manure from cattle, poultry, and pigs; (2) wood materials such as wood or bark, sawdust, timber slash, and millscrap; (3) municipal waste such as waste paper and yard clippings; and (4) energy crops such as poplar, willow, switchgrass, alfalfa, prairie bluestream, corn, soybeans, and the like. The feedstock may be made from biomass by any means now known or developed in the future, or may simply be a by-product of another process. Sugars may also be derived from wheat, corn, sugar beets, sugarcane, or molasses. The sugar is combined with water to provide an aqueous feed solution having a concentration effective to hydrogenate the sugar. Typically, suitable sugar concentrations are in the range of about 5% to about 70%, with a range of about 40% to 70% being more common in industrial applications.

[0023] Additionally or alternatively, suitable feedstock solutions include, but are not limited to, oxygenated hydrocarbons (C 2+ O 1+ , such as cyclic ethers, esters, ketones, lactones, carboxylic acids), vegetable oils (e.g., polyunsaturated fatty acids), olefins (e.g., olefins and aromatic compounds such as C3-C 12 olefins), alkynes, aldehydes, imines, nitriles, thiols, disulfides, thioesters, thioethers, phenols, other aromatic hydrocarbons / aromatic compounds, and combinations thereof. In some embodiments, the feed stream comprises water and oxygenated hydrocarbons (C 2+ O 1+ In some embodiments, the oxygen-containing hydrocarbon is a carbohydrate.

[0024] Reference Figure 1 , the reactor 12 includes a hydrogen inlet 26 that fluidically connects the reactor 12 to a hydrogen conduit 28. A gas delivery device 30 can be disposed in the hydrogen conduit 28 to deliver hydrogen from a hydrogen source 32, such as a reservoir or an upstream processing unit, to the reactor 12. In some embodiments, the 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. Although the hydrogen inlet 26 and the feed inlet 14 are located in the reactor 12, the hydrogen inlet 26 and the feed inlet 14 are located in the reactor 12. Figure 1 The hydrogen inlet 26 is oriented in a co-current direction in FIG. 1 , but it should be understood that the hydrogen inlet 26 can be arranged in a counter-current orientation (i.e., supplied into the bottom of the reactor 12). The hydrogen conduit 28 can include a valve 36 for controlling the flow of hydrogen to the reactor 12. Although not shown in FIG. Figure 1 , but the feedstock and hydrogen may be blended, mixed, or otherwise combined in a mixer prior to being delivered to reactor 12.

[0025] In some embodiments, reactor 12 includes a hydrogenation catalyst 38 disposed therein. The hydrogenation reaction can be carried out in a reactor of any suitable design, without limitation to design, size, geometry, flow rate, etc., including a continuous flow reactor, a batch reactor, a semi-batch reactor, or a multi-system reactor. Reactor system 10 can also use a fluidized catalytic bed system, a swing bed system, a fixed bed system, a moving bed system, or above-mentioned combinations. The reaction of the present disclosure is typically implemented using a continuous flow system in steady-state equilibrium.

[0026] In some embodiments, the reactor system 10 is operated as a fixed trickle bed reactor with shell-and-tube heat exchange, wherein the hydrogen gas and feed solution are introduced at the top of the reactor 12 and allowed to flow downwardly through a fixed bed of hydrogenation catalyst 38. Advantages of a trickle bed reactor include simple mechanical design, simplified operation, and potentially simplified catalyst development. The main design challenge is to ensure that the heat and mass transfer requirements of the reaction are met. The main operating challenges of a trickle bed reactor are: uniform loading of the hydrogenation catalyst 38, uniform introduction of the gas feed and the liquid feed, and avoiding bypassing some of the hydrogenation catalyst 38 due to channeling of the reactants as they flow through the reactor 12.

[0027] In some embodiments, the reactor system 10 is operated as a slurry reactor. A trickle bed reactor is loaded with a fixed hydrogenation catalyst 38, while a slurry reactor contains a flowing mixture of reactants, products, and hydrogenation catalyst 38 particles. Maintaining a uniform mixture throughout the reactor 12 includes active mixing from a mixer or pump. In addition, in order to remove the product, the catalyst particles must be separated from the product and unreacted feed by filtration, sedimentation, centrifugation, or some other means. The advantage of a slurry reactor is primarily that active mixing can achieve higher heat and mass transfer rates per unit reactor volume.

[0028] In some embodiments, the feed solution and hydrogen are reacted by passing through the hydrogenation catalyst 38 in the reactor 12. In some embodiments, the heat exchangers 22 and 34 heat the feed solution and hydrogen gas flow to a temperature of from 5°C to 700°C, from 10°C to 500°C, from 20°C to 300°C, or from 50°C to 180°C. In some embodiments, the pressure of the reactor 12 is maintained at from 0 psig to 5000 psig or from 100 psig to 3000 psig. The hydrogenation catalyst 38 can be configured in the reactor 12 in a variety of configurations, including but not limited to a single fixed bed or in a shell and tube arrangement. In some embodiments, the reactor system 10 includes a heating system configured to provide heat to the reactor 12 to maintain the desired operating temperature. In some embodiments, the heating system uses, for example, a heating element (e.g., an electric heater), a heating fluid, or a combination thereof to provide heat to the reactor 12. The heating system can be configured outside the reactor. Additionally or alternatively, the heating system can be configured in a shell and tube configuration, where a heating fluid provides heat via the shell side or the tube side to the hydrogenation catalyst 38. In some embodiments, the temperature of the reactor 12 can also be controlled by recycling the reaction products back to the reactor 12 to reduce the reaction exotherm.

[0029] The product stream exits the reactor 12 through at least one reactor outlet 50 and is optionally conveyed to a separator 54 via a product conduit 52. In some embodiments, the product conduit 52 includes a heat exchanger 56 to adjust the temperature of the product stream prior to entering the separator 54. The separator 54 may optionally separate unreacted hydrogen from unreacted reactants and products. The unreacted hydrogen may be recycled to the hydrogen source 32 via a hydrogen recycle conduit 58. Any suitable separator 54 may be used to separate the hydrogen from the unreacted reactants and products, including but not limited to a settling tank, a flash tank, a still, or a combination thereof. Although in Figure 1 Not shown, but in some embodiments, reactor 12 may include a gas outlet and a liquid outlet, wherein separation of vapor and liquid products occurs within reactor 12 without separator 54.

[0030] 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 deliver the product stream and unreacted reactants to the second separator 62. A heat exchanger 68 can control the temperature of the product stream and unreacted reactants entering the second separator 62, and a valve 70 can regulate the flow.

[0031] In some embodiments, second separator 62 is configured to separate product stream from unreacted reactant. Unreacted reactant can be recycled to feed conduit 16 via recirculation conduit 72, or otherwise discarded from process. The product stream leaving separator 62 via product conduit 74 can be sent to reservoir (storage) or downstream processing unit 76, such as aqueous phase reforming (APR) system or hydrodeoxygenation (HDO) system. Any suitable separator 62 can be used for separating product stream from unreacted reactant, including but not limited to distiller, evaporator, liquid-liquid extractor, chromatograph or its combination.

[0032] catalyst The method of the present invention can be used to regenerate hydrogenation catalysts, such as those used for hydrogenation of biomass. In some embodiments, suitable hydrogenation catalysts 38 for use in reactor system 10 include hydrogenation catalysts 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, alone or with promoters such as Ag, Au, Cr, Zn, Mn, Mg, Ca, Cr, Sn, Bi, Mo, W, B, P, and alloys or combinations thereof.

[0033] The hydrogenation catalyst may also include any of several supports, depending on the desired function of the catalyst. Exemplary supports include transition metal oxides, oxides formed from one or more metalloids, and active non-metals (e.g., carbon). Non-limiting examples of supports include, but are not limited to, carbon, silicon dioxide, aluminum oxide, zirconium oxide, titanium dioxide, vanadium oxide, ceria, silica-aluminate, zeolite, diatomaceous earth, hydroxyapatite, zinc oxide, chromium oxide, and mixtures thereof.

[0034] In some embodiments, catalyst is carbon-supported ruthenium (Ru / C) hydrogenation catalyst.In some embodiments, catalyst comprises about 0.1% to about 5% ruthenium by weight loaded on carbon particles, including but not limited to about 0.5%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0% and 4.5% ruthenium by weight.In some embodiments, catalyst comprises about 0.1% to about 4.0% or about 1.0% to about 2.0% carbon-supported ruthenium by weight. Catalyst can be in the form of extrudate, sheet (tablet), sphere, particle, powder, foam, coated structure or its combination.

[0035] Catalyst may be deactivated during the reaction or chemical process of its catalysis. For example, a hydrogenation catalyst as described herein may be deactivated during a biomass hydrogenation process. Catalyst may have a surface with an active site, which may affect the ability of the catalyst in catalyzing hydrogenation. During the hydrogenation process, the catalyst may be deactivated due to a variety of reasons, including, for example, blocking the active site by physical absorption (or deposition) of macromolecules, poisoning the active site by the impurities in the raw material, or a combination thereof. Catalyst poisoning may be caused by, for example, a chemical reaction or a strong interaction between an impurity (for example, a sulfur-containing compound) and the active site of the catalyst, thereby reducing the ability of the catalyst to catalyze hydrogenation, that is, thereby deactivating the catalyst. Along with the continuation of the hydrogenation process, the degree of deactivation of the catalyst may increase over time. Although the amount of the impurity in the raw material may be relatively low, under large volumes and over time, impurities can accumulate and adversely affect catalyst activity.

[0036] "Fresh" catalyst is used to mean a catalyst that has not been exposed to the feed solution or impurities from the feed under the hydrogenation conditions.

[0037] As used herein, "contaminated hydrogenation catalyst" or "contaminated catalyst" refers to a hydrogenation catalyst in which the active sites are at least partially deactivated due to use in a hydrogenation process (i.e., exposure to a feedstock solution under the conditions under which the catalyst is used to hydrogenate the feedstock solution). The degree of contamination may be affected by, for example, the composition of the catalyst, the duration and conditions of the hydrogenation process, the composition of the feedstock, and the amount of impurities in the feedstock.

[0038] As used herein, "regenerated hydrogenation catalyst" or "regenerated catalyst" refers to a contaminated catalyst whose catalytic ability is 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, the regenerated catalyst can be reused in a hydrogenation process and, during that process, again becomes a contaminated catalyst. In this case, the regenerated catalyst may also be referred to as a "freshly regenerated" catalyst, as opposed to the contaminated catalyst produced by such a regenerated catalyst.

[0039] The catalytic ability of the catalyst of regeneration or the catalytic ability of the polluted catalyst of the catalyst producing regeneration can be compared with the catalytic ability of fresh catalyst.For example, the catalytic ability of the polluted catalyst can be about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80% or about 90% of the catalytic ability of fresh catalyst.For example, the catalytic ability of the catalyst of regeneration can be about 80%, about 90%, about 95%, about 99%, about 100% or about 110% of the catalytic ability of fresh catalyst.In some embodiments, the catalyst of regeneration has higher catalytic ability than the polluted catalyst producing regeneration.For example, the regeneration method herein can recover at least a portion of the catalytic ability of the polluted catalyst, causing the catalytic ability of the catalyst of regeneration to increase.In some embodiments, the catalytic ability of the catalyst of regeneration can be about 105% to about 500% of the catalytic ability of the polluted catalyst producing regeneration, including about 120%, about 150%, about 200%, about 300%, about 400% or about 500%.

[0040] The catalytic capacity of a catalyst (e.g., a fresh catalyst, a contaminated catalyst, or a regenerated catalyst) can be measured by the conversion of the reagents in the feedstock in a reaction (e.g., a hydrogenation reaction) catalyzed by such a catalyst. As used herein, the "conversion rate" of a hydrogenation catalyst refers to the conversion of the hydrogenation catalyst over a duration (e.g., at least 1 hour to at least 1 day) of the reactants in the feedstock solution after being exposed to the feedstock solution for the hydrogenation cycle. The hydrogenation catalyst can be a fresh catalyst, a contaminated catalyst, or a regenerated catalyst. As used herein, a specific feedstock reactant (X i ) can be calculated as follows:

[0041] where n i is the number of moles of a particular feed reactant (e.g., sugar, olefin, vegetable oil, alkyne, aldehyde, imine, nitrile) at the start of the hydrogenation process (t=0) or after a specific duration (t) of the hydrogenation process. Conversion values ​​for fresh catalyst, contaminated catalyst, and regenerated catalyst can be compared under the same hydrogenation conditions (e.g., at a temperature of from 50° C. to 180° C. and a pressure of from 100 psig to 3000 psig) because conversion can be a function of temperature and pressure.

[0042] In some embodiments, reactor system 10 includes a pretreatment unit or pretreatment step to process the feed solution and / or hydrogenation catalyst 38. For example, the hydrogenation catalyst 38 can be reduced to an active state. For example, during production, the catalyst can be reduced and, in certain applications, then passivated with low levels of oxygen to stabilize the catalyst when exposed to air. The purpose of the reduction step is to convert any oxidized catalyst into a fully reduced state. For some feed solutions, a pretreatment step can be included upstream of reactor system 10. For example, sugars (e.g., sucrose) containing glycosidic bonds can be hydrolyzed before hydrogenation in reactor 12.

[0043] Catalyst regeneration During hydrogenation, catalyst impurities may accumulate on the surface of the hydrogenation catalyst 38 and reduce catalytic performance. As used herein, the term "catalyst impurities" or "impurities" refers to impurities that form deposits that accumulate on catalytic sites on the surface of the hydrogenation catalyst 38, restrict access to the catalytic sites, and / or reduce catalytic activity over time (i.e., resulting in lower conversion and yield of products). Exemplary catalyst impurities include, but are not limited to, carbon-containing impurities, sulfur-containing impurities, silicon-containing impurities, phosphorus-containing impurities, or iron-containing impurities.

[0044] In some embodiments, the hydrogenation catalyst 38 is regenerated into a regenerated catalyst by contacting the hydrogenation catalyst 38 with a flushing medium. In some embodiments, the flushing medium includes a vapor phase or a gaseous phase and a liquid phase. Unless otherwise indicated, the terms "vapor phase" and "gaseous phase" with respect to the flushing medium are used interchangeably herein, and the physical properties of the "gaseous phase" and "liquid phase" of the flushing medium are understood to be measured at 25° C. and 1 atmosphere. For example, the flushing medium can include water as the liquid phase and air or nitrogen in the vapor phase measured at 25° C. and 1 atmosphere.

[0045] Still refer to Figure 1, reactor 12 includes a gas phase inlet 78, which connects reactor 12 to a gas phase source 80 fluid via a gas phase conduit 82. A fluid delivery device 84 (e.g., a compressor or blower) can be configured in the gas phase conduit 82 to deliver the gas phase from the gas phase source 80 to reactor 12. The gas phase conduit 82 can include a heat exchanger 86 for controlling the temperature of the gas phase of the flushing medium and a valve 88 for controlling the flow of the gas phase to reactor 12. In some embodiments, the fluid delivery device 84 is configured for direct air or atmospheric capture, wherein the fluid delivery device 84 is in fluid communication with atmospheric air for compression or in direct fluid communication. Using air as the gas phase in the flushing medium provides a variety of advantages. Specifically, this will avoid having to purchase and store other oxidants (e.g., hydrogen peroxide) on site. In some embodiments, the gas phase source 80 includes a gas phase that contains, for example, about 0.1% to about 30% oxygen by volume. In some embodiments, the gas phase source 80 includes a source of an inert gas (e.g., nitrogen, argon, helium, neon, krypton, xenon, radon, or a combination thereof) and an oxygen source (e.g., a compressed tank) that can be used to change the O2 and / or inert gas content of the gas phase to the concentrations described herein. In some embodiments, the gas phase source 80 comprises at least 50% air by volume, such as 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, the gas phase source 80 comprises at least 90% nitrogen by volume, such as 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 supplied via the gas phase source 80 (e.g., air or inert gas), the oxidizing atmosphere of the flushing medium (e.g., as measured by the amount of oxygen in the gas phase) can be customized.

[0046] In some embodiments, the reactor 12 includes a liquid phase inlet 90 that fluidly connects the reactor 12 to a liquid phase source 92 via a liquid phase conduit 94. In some embodiments, the liquid phase comprises water. A pump 96 can be disposed in the liquid phase conduit 94 to transport the liquid phase from the liquid phase source 92 to the reactor 12. The liquid phase conduit 94 can include a heat exchanger 98 for controlling the temperature of the liquid phase of the flushing medium and a valve 100 for controlling the flow of the gas phase to the reactor 12. Although in Figure 1 Not shown, but the liquid and gas phases may be blended, mixed, or otherwise combined in a mixer before being delivered to reactor 12.

[0047] In some embodiments, the regenerated hydrogenation catalyst can be produced by maintaining contact of the flushing medium with the hydrogenation catalyst 38 at a regeneration temperature, regeneration pressure, and duration sufficient to remove at least a portion of the impurities from the hydrogenation catalyst 38. Contacting the flushing medium with the hydrogenation catalyst 38 can occur with any suitable flow scheme, including continuous flow of the flushing medium over the hydrogenation catalyst 38 without recirculation, continuous flow of the flushing medium over the hydrogenation catalyst 38 with partial or full recirculation, intermittent flow, or semi-intermittent flow. In some embodiments, the flushing medium leaves the reactor 12 through the reactor outlet 50 and is recycled to the flushing 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 flushing medium can be recycled several times before being replaced by fresh flushing medium. "Recycle rate" refers to the ratio of recycled material (e.g., water) to fresh material. The system of the present invention can 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 recycled water per one equivalent of fresh water introduced into the system). High recirculation rates can reduce water consumption, which is particularly advantageous in large-scale production.

[0048] Regeneration cycle In some embodiments, the first flush medium comprises liquid water measured at 25° C. and 1 atmosphere, 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. In some embodiments, the oxygen content of the gas phase of the first flush medium is from about 0.1% to about 30% by volume, such as from about 0.5% to about 30%, from about 1% to about 30%, from about 1% to about 25%, from about 1% to about 20%, or from about 5% to about 20% by volume. In some embodiments, the oxygen content of the gas phase of the first flush medium is from about 5% to about 20% by volume. In some embodiments, the oxygen content of the gas phase of the first flush medium is from about 1%, about 5%, about 10%, about 15%, about 20%, or about 25% by volume. In some embodiments, the oxygen content of the gas phase of the first flushing medium is about 20% by volume. The gas phase of the first flushing medium may also contain an inert gas. The inert gas may be, for example, nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide, or a combination thereof.

[0049] The gas phase of the first flushing medium can have a composition identical or similar to that of air. In some embodiments, the first flushing medium is included in liquid water and a gas phase measured at 25 ° C and 1 atmosphere, and the gas phase comprises 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. In some embodiments, the gas phase of the first flushing medium is composed of air. As used herein, "air" refers to the gas around the earth, which can vary regionally and is a function of various factors such as temperature and pressure. As an example, the term "air" can refer to a gas composition consisting of about 78% by volume of nitrogen, about 20.9% by volume of oxygen, about 0.9% by volume of argon, about 0.04% by volume of 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 dry volume percentage (volume %). In this example, a gas phase comprising at least 50% air by volume will contain at least 10% oxygen by volume. As non-limiting examples, the gas phase of the first flushing medium can 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 content and nitrogen content (net volume %) of some exemplary gas phases of the first flushing medium (composed of the supplied gas) are as follows:

[0050] Method of the present invention can comprise keeping hydrogenation catalyst and first flushing medium contact continuous air treatment duration to produce air-treated catalyst.As used herein, term " air treatment ", " air-treated ", " oxygen treatment ", " oxygen-treated " and similar term refer to the processing that carries out with air or any other natural gas composition or artificial gas composition that comprise oxygen.The air treatment duration can be at least 30 minutes, includes 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 approximately 2 hours to approximately 8 hours, such as approximately 2 hours to approximately 4 hours.

[0051] In some embodiments, the second flush medium comprises liquid water measured at 25° C. and 1 atmosphere, and a gas phase comprising at least 90% nitrogen by volume, including but not limited to at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% nitrogen by volume. In some embodiments, the gas phase of the second flush medium comprises at least 95% nitrogen by volume. In some embodiments, the gas phase of the second flush medium comprises at least 99% nitrogen by volume. In some embodiments, the gas phase of the second flush medium consists of nitrogen. In some embodiments, the gas phase of the second flush medium is substantially free of oxygen. As used herein, the term “substantially free of oxygen” refers to less than 1%, or less than 0.5%, less than 0.1%, or less than 0.05% oxygen.

[0052] The gas phase of the second flushing medium can have a composition different from the gas phase of the first flushing medium. Especially, with regard to respective oxygen content (for example, in percentage by volume), the gas phase of the first flushing medium and the gas phase of the second flushing medium can be different. In some embodiments, the oxygen content that the gas phase of the second flushing medium has is less than the oxygen content of the gas phase of the first flushing medium. Therefore, catalyst can be exposed to an atmosphere with stronger oxidizing property by contacting the first flushing medium, and then be exposed to an atmosphere with weaker or even inert oxidizing property by contacting the second flushing medium. In specific embodiments, the gas phase of the first flushing medium comprises approximately 5% to approximately 20% oxygen by volume (for example, air or a similar gaseous composition with approximately 20% oxygen), and the gas phase of the second flushing medium is substantially free of oxygen (for example, 99% or higher nitrogen).

[0053] Method of the present invention can comprise keeping hydrogenation catalyst and the second flushing medium contacting continuous nitrogen treatment duration to produce regenerated hydrogenation catalyst.The nitrogen treatment duration can be at least 30 minutes, includes 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 approximately 4 hours to approximately 24 hours, such as approximately 12 hours to approximately 24 hours.In some embodiments, the nitrogen treatment duration is approximately 20 hours.

[0054] The duration of the air treatment and the duration of the nitrogen treatment in a given regeneration cycle can be adjusted and coordinated 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 in which the flushing medium is recirculated at a recirculation rate of 6-10, such as a recirculation rate of 8, the duration of the air treatment can be 2 hours to 4 hours and the duration of the nitrogen treatment can be approximately 20 hours.

[0055] The contact of the first flushing medium or the second flushing medium with the catalyst can be for example carried out by making flushing medium flow through the surface of catalyst.Can keep contact by controlling the flow of flushing medium in whole air treatment duration and nitrogen treatment duration.As described herein, the liquid and gaseous portion of flushing medium can be recycled (as designed by recirculation rate as described herein), and system of the present invention can provide the continuous flow of the flushing medium of recycling to keep the contact of the first flushing medium or the second flushing medium with catalyst.Usually, the contact of the gaseous component of the first flushing medium with the catalyst starts (for example, opening) before the contact of the gaseous component of the second flushing medium with the catalyst.When performing multiple regeneration cycles, usually before the contact of the gaseous component of the first flushing medium with the catalyst in the next cycle, stop the contact of the gaseous component of the second flushing medium with the catalyst in the last cycle.Therefore, system of the present invention allows catalyst to be exposed to significantly different atmospheres (for example, from main air to main nitrogen) in single regeneration cycle or from a regeneration cycle to another regeneration cycle.

[0056] In some embodiments, the regeneration temperature is from 50° C. to 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 performed at a temperature of from about 70° C. to about 120° C.

[0057] In some embodiments, the regeneration pressure is from 20 psig to 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 carried out at a pressure of from about 50 psig to about 200 psig.

[0058] 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 occurs for 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 a week, or longer.

[0059] In some embodiments, the oxygen content in the flush medium (e.g., the gas phase of the first flush medium) is selected based on the amount of hydrogenation catalyst 38 in the reactor 12. In some embodiments, the first flush medium comprises from 0.1 to 10 -3 (mol / g / h) to 100*10 -3 In some embodiments, the O2 / catalyst / hour flow rate ratio is at least 0.1*10 -3 (mol / g / h), such as at least 0.5*10 -3 (mol / g / h) or at least 1*10 -3 (mol / g / h). In some embodiments, the O2 / catalyst / hour flow rate ratio is less than 100*10 -3 (mol / g / h), such as less than 50*10 -3 (mol / g / h), less than 10*10 -3 (mol / g / h) or less than 5*10 -3 (mol / g / h).

[0060] In some embodiments, the water content of the first flush medium is based on the amount of hydrogenation catalyst 38 in reactor 12. In some embodiments, the first flush medium comprises a water to catalyst flow rate ratio (HO / catalyst / hour) (HO / cat / h) of from 1 (g / g / h) to 100 (g / g / h). In some embodiments, the HO / catalyst / hour ratio of the first flush medium is at least 1 (g / g / h), such as at least 2 (g / g / h), at least 5 (g / g / h), or at least 10 (g / g / h). In some embodiments, the HO / catalyst / hour ratio of the first flush medium is less than 100 (g / g / h), such as less than 50 (g / g / h), less than 20 (g / g / h), or less than 10 (g / g / h).

[0061] In some embodiments, the second flushing medium comprises from 0.1 to 10 -3 (mol / g / h) to 100*10 -3In some embodiments, the N2 / catalyst / hour flow rate ratio is at least 0.1*10 -3 (mol / g / h), such as at least 0.5*10 -3 (mol / g / h) or at least 1*10 -3 (mol / g / h). In some embodiments, the N2 / catalyst / hour flow rate ratio is less than 100*10 -3 (mol / g / h), such as less than 50*10 -3 (mol / g / h), less than 10*10 -3 (mol / g / h) or less than 5*10 -3 (mol / g / h).

[0062] In some embodiments, the water content of the second flush medium is based on the amount of hydrogenation catalyst 38 in reactor 12. In some embodiments, the second flush medium comprises a water to catalyst flow ratio (HO / catalyst / hour) (HO / cat / h) of from 1 (g / g / h) to 100 (g / g / h). In some embodiments, the HO / catalyst / hour ratio of the second flush medium is at least 1 (g / g / h), such as at least 2 (g / g / h), at least 5 (g / g / h), or at least 10 (g / g / h). In some embodiments, the HO / catalyst / hour ratio of the second flush medium is less than 100 (g / g / h), such as less than 50 (g / g / h), less than 20 (g / g / h), or less than 10 (g / g / h).

[0063] The nitrogen content of the gas phase of the second flush medium can be selected to provide a desired inert atmosphere compared to the oxidizing atmosphere provided by the gas phase of the first flush medium (e.g., at least 90% air by volume). In some embodiments, the second flush medium includes a gas phase comprising at least 99% nitrogen by volume measured at 25° C. and 1 atmosphere.

[0064] Including water in the flushing medium provides several advantages. First, the water in the flushing medium acts as a heat sink, which allows for improved control of the temperature of the reactor 12 relative to a flushing medium consisting solely of gas. This improved thermal control avoids the creation of hot spots that could burn off catalyst supports such as carbon. Water is also a polar solvent that can facilitate the removal of certain impurities such as ionic salts and other polar moieties. Furthermore, including water in the flushing medium allows the hydrogenation catalyst 38 to remain moist during regeneration. A flushing medium consisting solely of gas can dry out the catalyst, which can cause cracks in a fixed bed and lead to increased replacement frequency.

[0065] In some embodiments, the flushing medium is substantially free of hydrogen peroxide or is completely free of hydrogen peroxide. As used herein, the term "substantially free of hydrogen peroxide" means 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 of hydrogen peroxide or is completely free of hydrogen peroxide before entering reactor 12.

[0066] In some embodiments, one or more regeneration cycles are used to produce a regenerated hydrogenation catalyst. For example, the method can include subjecting the contaminated hydrogenation catalyst to one, two, three, four or more regeneration cycles as described herein, and the conditions (such as temperature, pressure and duration) of one regeneration cycle can be controlled independently of the corresponding conditions of another regeneration cycle. For example, a first regeneration cycle can be performed at a different temperature or different pressure than a second regeneration cycle, or for different durations.

[0067] Unlike typical catalyst regeneration processes, which operate under gas-phase conditions at temperatures exceeding 200° C. (e.g., decoking and desulfurization reactions), or utilize oxidants that degrade the catalyst's physical structure over time (e.g., H 2 O 2 -based regeneration), the present disclosure provides a method for regenerating a hydrogenation catalyst 38 with a flushing medium that operates under less severe conditions (e.g., temperatures below 200° C.). As reported in co-pending U.S. Patent Application No. 17 / 891,093, a flushing medium comprising water, oxygen, and an inert / diluent gas effectively restores catalytic activity by removing impurities from the hydrogenation catalyst and maintaining the catalyst's structural integrity (e.g., total surface area, pore size, pore volume) at specific regeneration pressures and regeneration temperatures. Surprisingly and notably, as shown in the present disclosure, by switching the flushing medium's gas phase from air (a higher oxygen or oxidizing atmosphere) to nitrogen (a lower oxygen or inert atmosphere), regeneration efficiency can be further improved because more impurities (such as sulfur-containing impurities) can be removed from the contaminated catalyst during the duration of the nitrogen treatment. By adapting the atmosphere transitions between different gas phases, the system described herein can more efficiently regenerate contaminated hydrogenation catalysts at reduced costs. For example, the nitrogen treatment duration can be adjusted based on the recirculation rate of the flushing medium to reduce water consumption and improve the removal of impurities (e.g., sulfur-containing impurities).

[0068] Furthermore, the system of the present invention allows for a "pulse" regeneration process with multiple regeneration cycles, with each cycle switching between an oxidizing atmosphere (e.g., an air-treated pulse) and an inert atmosphere (e.g., a nitrogen-treated pulse), thereby providing greater flexibility and efficiency in controlling the regeneration process. More importantly, the "pulse" regeneration system of the present invention can more effectively remove sulfur from contaminated catalysts, where the feedstock contains higher than normal amounts of sulfur-containing impurities, than systems that do not use air / nitrogen switching. Thus, the system of the present invention exhibits unexpected and superior performance compared to previous systems in regenerating catalysts used to hydrogenate feedstocks having high sulfur contents.

[0069] In another aspect, the present disclosure provides a method for producing a regenerated hydrogenation catalyst from a contaminated 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 a contaminated hydrogenation catalyst, wherein the contaminated hydrogenation catalyst comprises an amount of sulfur derived from the at least one sulfur-containing impurity of the feedstream, and The contaminated hydrogenation catalyst is subjected to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flush medium for an air treatment duration to produce an air-treated catalyst, wherein the first flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a gas phase comprising oxygen, and (b) contacting the air-treated catalyst with a second flush medium for a nitrogen treatment duration to produce a nitrogen-treated catalyst, wherein the second flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a vapor phase comprising at least 90% by volume nitrogen, The amount of sulfur in the nitrogen-treated hydrogenation catalyst is reduced relative to the amount of sulfur in the contaminated hydrogenation catalyst.

[0070] The contaminated hydrogenation catalyst can be, for example, a hydrogenation catalyst that has been exposed to a feedstock solution under specific hydrogenation conditions (e.g., temperature, pressure, concentration of feedstock) 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 contaminated hydrogenation catalyst can be generated by exposing a fresh catalyst that has never been exposed to a feedstock solution under specific hydrogenation conditions or by exposing a freshly regenerated catalyst to specific hydrogenation conditions.

[0071] Suitable first flushing medium and second flushing medium include those mentioned above. In some embodiments, the gas phase of the first flushing medium comprises about 0.1% to about 30% oxygen by volume. The gas phase of the first flushing medium can also comprise 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 comprises at least 90% air by volume. In some embodiments, the gas phase of the second flushing medium comprises at least 99% nitrogen by volume. In some embodiments, the gas phase of the second flushing medium is substantially free of oxygen. In some embodiments, method includes making the catalyst undergo a set of continuous regeneration cycles through nitrogen treatment operation (a) and operation (b), each operation having a corresponding treatment duration, to produce a regenerated hydrogenation catalyst. For example, method can include making the catalyst undergo a set of continuous regeneration cycles through nitrogen treatment as described herein once, twice, three times, four times or more. Advantageously, the conditions (such as temperature, pressure and duration) of each regeneration cycle can be independently controlled. Furthermore, based on the sulfur content in the feedstock, the amount of sulfur in the contaminated catalyst, and the recirculation rate of the flushing medium, the air treatment duration and the nitrogen treatment duration in each regeneration cycle can be coordinated to improve the regeneration efficiency.

[0072] In some embodiments, the duration of air treatment in one or more regeneration cycles is at least 30 minutes, such as about 2 hours to 4 hours.

[0073] In some embodiments, the duration of nitrogen treatment in one or more regeneration cycles is at least 30 minutes or at least 4 hours, such as about 12 hours to 24 hours.

[0074] In some embodiments, the amount of sulfur in the nitrogen-treated hydrogenation catalyst or the regenerated hydrogenation catalyst is reduced by at least 5% relative to the amount of sulfur in the contaminated hydrogenation catalyst. The reduction can be at least 10% reduction, at least 15% reduction, at least 20% reduction, at least 30% reduction, at least 40% reduction, at least 50% reduction, or at least 60% reduction relative to the sulfur content of the contaminated hydrogenation catalyst.

[0075] 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% relative to the amount of sulfur in the contaminated hydrogenation catalyst. In some embodiments, multiple regeneration cycles are performed in the methods of the present invention (e.g., a total of two, three, four, five, six, seven, eight, nine, or ten cycles), wherein at least one cycle includes an air treatment duration of at least 30 minutes and a nitrogen treatment duration of at least 4 hours, and wherein the amount of sulfur in the regenerated hydrogenation catalyst is reduced by at least 5% relative to the amount of sulfur in the contaminated hydrogenation catalyst.

[0076] In some embodiments, the regeneration cycle is performed at a temperature of from about 70° C. to about 120° C. In some embodiments, multiple regeneration cycles are performed in the methods of the present invention (e.g., a total of two, three, four, five, six, seven, eight, nine, or ten cycles), and at least one of the multiple regeneration cycles is performed at a temperature of from about 70° C. to about 120° C.

[0077] In some embodiments, the regeneration cycle is performed at a pressure of from about 50 psig to about 200 psig. In some embodiments, multiple regeneration cycles are performed in the methods of the present invention (e.g., a total of two, three, four, five, six, seven, eight, nine, or ten cycles), and at least one of the multiple regeneration cycles is performed at a pressure of from about 50 psig to about 200 psig.

[0078] The method of the present invention is particularly effective in regenerating catalysts for hydrogenating raw materials with higher than normal levels of sulfur-containing impurities. In some embodiments, the feed stream has an amount of at least 0.1 ppm of sulfur, 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 of sulfur. In some embodiments, the feed stream has an amount of at least 0.5 ppm, such as at least 1.0 ppm or at least 5 ppm of sulfur.

[0079] 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, the conditions for further regeneration cycles (such as temperature, pressure, air treatment duration, and nitrogen treatment duration) can be adjusted to improve efficiency. In some embodiments, the method of the present invention also includes: measuring the first sulfur content of the first flushing medium after the first flushing medium contacts the catalyst in (a) and / or measuring the second sulfur content of the second flushing medium after the second flushing medium contacts the catalyst in (b); and subjecting the catalyst treated with nitrogen to a set of continuous operations (a) and operations (b), each operation having a corresponding 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 flushing medium or the second flushing medium or by an inductively coupled plasma (ICP) method.

[0080] In some embodiments, the regenerated hydrogenation catalyst exhibits excellent retention of catalytic activity after the regeneration process. As used herein, the terms "retain," "retaining," or "retention" with respect to a reference value include both partial values ​​and increased values ​​relative to the reference value. For example, a particular parameter (e.g., the conversion of the regenerated catalyst) may retain less than 100% or greater than 100% of the reference parameter (e.g., the conversion of the fresh catalyst or the contaminated catalyst from which the regenerated catalyst was produced).

[0081] In some embodiments, the catalyst of pollution has a catalytic ability (for example, as measured by conversion rate value) lower than that of fresh catalyst. The catalytic ability of the catalyst of pollution can be increased to the level of the catalytic ability of the fresh (or freshly regenerated) catalyst of the catalyst close to the generation of pollution by regeneration method as described herein. That is, regeneration method herein can be used for the catalytic ability of the catalyst of pollution to be restored to the level of fresh (or freshly regenerated) catalyst. The conversion rate value of the catalyst of regeneration as described herein (as a measure of catalytic ability) or the conversion rate value of the pollution of the catalyst of regeneration can be compared with the conversion rate value of fresh catalyst. For example, the conversion rate value of the catalyst of pollution can be about 50%, about 60%, about 70%, about 80% or about 90% of the conversion rate value of fresh catalyst. For example, the conversion rate value of the catalyst of regeneration can be about 70%, about 80%, about 90%, about 95%, about 99%, about 100% or about 110% of the catalytic ability of fresh catalyst. In some embodiments, the conversion rate value of the catalyst of regeneration is higher than the conversion rate value of the catalyst of pollution by at least 5%, at least 10%, at least 20%, at least 50%, at least 70%, at least 90% or at least 100%.In some embodiments, the catalyst of regeneration 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 rate value of the catalyst of pollution.As an example, the conversion rate value of fresh catalyst is 0.96, and the conversion rate value of the catalyst of pollution is 0.70 (or 73% of fresh catalyst).After regeneration, the conversion rate value of the catalyst of regeneration is 0.94 (or 98% of fresh catalyst).In this example, the catalyst of regeneration retains 134% of the conversion rate of the catalyst of pollution (or, the conversion rate value of the catalyst of regeneration is higher than the conversion rate value of the catalyst of pollution by 34%).

[0082] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention belongs.As defined herein and all definitions used should be understood to control dictionary definitions, the definitions in the files incorporated by reference, and / or the ordinary meaning of the defined terms.As used herein, the terms "include (include)" and "include (including)" have the same meaning as the terms "comprise (comprise)" and "comprising (comprising)". The terms "comprise (comprise)" and "comprising (comprising)" should be interpreted as "open" transition terms, which allow additional components to be included in addition to those components described in the claims. The terms "consist of ... and "consisting of ... should be interpreted as "closed" transition terms, which do not allow additional components to be included in addition to the components described in the claims. The term "substantially consisting of ... consisting of (consisting essentially of)" should be interpreted as partially closed and only allow the additional components to be included that will not fundamentally change the property of the claimed subject matter. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" include plural schemes. The modifier "about" used in conjunction with an amount includes the stated value and has the meaning specified by the context (for example, it includes at least the degree of error associated with the measurement of the particular amount). The modifier "about" should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. For example, the expression "from about 2 to about 4" also discloses a range of "from 2 to 4". The term "about" can refer to plus or minus 10% of the number shown. For example, "about 10%" can represent a range of 9% to 11%, and "about 1" can mean from 0.9-1.1.

[0083] The invention has been described in terms of one or more preferred embodiments, and it should be understood that many equivalents, alternatives, variations and modifications, besides those expressly stated, are possible and within the scope of the invention. Example

[0084] Example 1 The hydrogenation catalyst with impurities is regenerated using a flushing medium comprising a liquid phase containing water and a gas phase containing nitrogen and oxygen. This process is known as "wet air oxidation regeneration" (WAOR). Fresh Ru / C hydrogenation catalysts are deactivated by hydrogenating glucose monohydrate or corn syrup feeds. The hydrogenation reaction operation continues for many days until the hydrogenation catalyst is deactivated. WAOR experiments are carried out on deactivated hydrogenation catalysts. The conditions of the standard WAOR process are as follows: at 100% air, an inlet temperature of 100°C-110°C, a reactor pressure of 100 psig, and water and air flow for 24 hours. After 24 hours, the water flow continues, but before introducing hydrogen to reduce the catalyst, the system is purged with N2 to remove any trace of oxygen. In various studies conducted herein, oxygen levels of 1% (e.g., 5% air, 95% nitrogen) to 20% (e.g., 100% air) are used in the gas phase of the flushing medium to have similar results. As used herein, nitrogen is supplied as a high purity gas (eg, 99% or higher).

[0085] While standard WAOR regeneration may help restore catalyst activity during testing when using most corn syrups, it is not sufficient to restore the catalyst when using a high sulfur corn syrup feed, even with extended periods of air. Sulfur impurities deposited on the catalyst can be removed during the regeneration process, and the removal of such sulfur impurities can be measured by the amount of sulfur in the effluent liquid phase (water) of the flushing medium (e.g., by weight or wt% relative to the sulfur in the feed). Notably, it was observed in some experiments that the majority of the sulfur was removed during the WAOR process only after switching to a N2 purge, while little or no sulfur was removed under air flow. Furthermore, the results of WAOR experiments conducted at different air flow durations (e.g., 24 hours versus 4 hours) were compared, indicating that the sulfur content in the effluent water peaked at approximately the same time after switching to N2 regardless of the air flow duration (e.g., peaking between 2 hours and 6 hours after switching to N2 after 4 hours of air flow or 24 hours of air flow). More importantly, similar amounts of sulfur were removed (as measured as wt% relative to the sulfur in the feed) in these experiments with different air flow durations (17% removal at 24 hours of air flow versus 14% removal at 4 hours of air flow). These results indicate that the major amount of sulfur removal from the deactivated catalyst occurs after the N2 flow is introduced, rather than during the air flow.

[0086] After approximately 50 days of reaction with the feed stream, further regeneration studies were conducted on the 2 wt% Ru / C catalyst. Samples of the reactor effluent were collected during the regeneration process, after nitrogen was introduced to flush the reactor of oxygen, and during the wet reduction. No sulfur was detected under air flow during regeneration, but significant levels were observed after the atmosphere in the reactor was switched to N2 and then H2 ( Figure 2 ). These results indicate that changing the reactor atmosphere can affect the removal of sulfur from the catalyst.

[0087] Similar results were observed from regeneration in another study in which the sulfur content of the effluent was tracked every four hours (Table 1). The maximum sulfur content observed during the air flow was at the end of the time air was 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), indicating a significant increase in sulfur removal after switching from air to nitrogen. This result again indicates that sulfur removal is related to the change in reactor atmosphere.

[0088] Table 1. Sulfur content of the reactor effluent from the regeneration process.

[0089]

[0090] In a further study, air was supplied for only 4 hours instead of flowing through the reactor for 24 hours during regeneration. The first ICP sample was taken only a few hours after the air flow was stopped, but the sulfur levels in the effluent appeared to have passed their peak and were declining. These data indicate that sulfur levels peaked after switching from air to N2 ( Figure 3 ).

[0091] With a normal corn syrup feed and a standard WAOR regeneration procedure, the catalyst can have a cycle time of about 50-70 days before the catalyst needs to be regenerated to maintain adequate conversion of glucose to sorbitol. However, when using corn syrup with higher than normal levels of sulfur (e.g., 0.5 ppm or higher) as a feed, a 3- to 4-fold higher rate of catalyst deactivation has been observed. The high loading of sulfur impurities on the catalyst requires an earlier than normal WAOR. The first regeneration was required after only 30 days using these feeds ( Figure 4 , regenerated at approximately 380 days). Even after this regeneration, poor catalyst activity was observed, and a second regeneration was required after only 10 days ( Figure 4 , regenerated at approximately 390 days). Significant levels of sulfur were observed from the effluents of these regenerations.

[0092] Based on the observation that sulfur was primarily removed from the catalyst after switching the air flow to nitrogen, and the assumption that the short cycle time at 380 days in operation was due to inadequate sulfur removal from the catalyst, a new "pulse" regeneration procedure was developed. The "pulse" procedure was designed to use the same reactor temperature, pressure, and gas and liquid flow rates, but to switch from air to nitrogen after only 12 hours. After purging with nitrogen for 12 hours, air was reintroduced. After another 12 hours of air flow, nitrogen was introduced, and then a final cycle of 12 hours air / 12 hours nitrogen was performed. 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 surge until after the atmosphere was switched to N2. Along with the surge in sulfur levels, conductivity rapidly increased to 350 uS / cm, and pH dropped from about 3.7 to 3.2. Each of these effects is consistent with sulfur being removed from the catalyst as an acidic substance (e.g., H2SO4). After switching back to air, sulfur levels and conductivity decreased, while pH increased. The 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 the amount of the first cycle. The third cycle further removed a significant amount of sulfur from the catalyst (although the amount was less than the amount of the first and second cycles).

[0093] After this pulse regeneration, the feed was reintroduced into the reactor after being reduced. This feed still contained elevated levels of sulfur. Remarkably, the catalytic activity returned to the levels seen at the start of the run, indicating that the pulse regeneration process was more effective at removing high levels of sulfur poisons from the catalyst than the previous standard WAOR regeneration process. The catalyst was then run for 19 days, at which point another regeneration was required due to high levels of sulfur poisons in the feed. Similar to the previous regeneration process, sulfur levels surged after switching to N2, which is also consistent with the conductivity data ( Figure 6 Due to the ease of conductivity measurement, the rapidity of analyzing samples, and the potential for online measurement, conductivity data was used as a reliable indicator of sulfur content. The regeneration process showed similar conductivity levels in the third pulse as in the second, so a fourth pulse was performed.

[0094] The pulse regeneration procedure was further developed. At various plants, attempts were made to reduce the air purge from 12 hours to just 30 minutes. This change would 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, indicating incomplete sulfur oxidation during each pulse. The pulse duration in these processes can be further designed to maximize sulfur removal in a short period of time.

[0095] In summary, a pulse regeneration process using air / N2 atmosphere switching was implemented for the hydrogenation catalyst, and the performance of the catalyst regenerated by the method of the present invention was restored to an activity closer to the start of operation than the activity of the catalyst regenerated by the previous non-pulse regeneration. A significant amount of sulfur was removed during the nitrogen treatment, and high levels of sulfur can be removed by multiple regeneration cycles (pulses). For example, the sulfur level in the effluent of the second regeneration cycle and the third regeneration cycle (pulse) can still be high. The conductivity and pH of the effluent are used to track the amount of sulfur removed from the catalyst. In some tests, a pulse regeneration process was performed using a 30-minute air flow and a 23.5-hour nitrogen flow in each pulse, which was still effective in removing a significant amount of sulfur from the catalyst.

[0096] For reasons of completeness, various aspects of the invention are set out in the following numbered items: Item 1. A method for hydrogenating biomass, the method comprising: Containing water and oxygen-containing hydrocarbon (C 2+ O 1+ ) with hydrogen in the presence of a hydrogenation catalyst for a hydrogenation duration to produce a first hydrogenated product stream and contaminated hydrogenation catalyst; subjecting the contaminated hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flush medium for an air treatment duration to produce an air-treated catalyst, wherein the first flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a gas phase comprising oxygen, and (b) contacting the air-treated catalyst with a second flush medium for a nitrogen treatment duration to produce a regenerated hydrogenation catalyst, wherein the second flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a vapor phase comprising at least 90% by volume nitrogen; and The feed stream is catalytically reacted with hydrogen in the presence of the regenerated hydrogenation catalyst to further produce a second hydrogenated product stream.

[0097] Item 2. The method according to Item 1, wherein the air treatment duration is at least 30 minutes.

[0098] Item 3. The method according to any one of items 1-2, wherein the nitrogen treatment lasts for at least 30 minutes.

[0099] Item 4. The method of any one of items 1-3, wherein the regeneration cycle is performed at a temperature of from about 70°C to about 120°C.

[0100] Item 5. The method of any one of items 1-4, wherein the regeneration cycle is conducted at a pressure of from about 50 psig to about 200 psig.

[0101] Item 6. The method according to any one of items 1 to 5, wherein the first flushing medium comprises from 0.1 to 10 -3 (mol / g / h) to 100 * 10 -3 The oxygen to catalyst flow ratio (O2 / catalyst / hour) is (mol / g / h).

[0102] Item 7. The method according to any one of items 1-6, wherein the first flush medium and / or the second flush medium comprises a water to catalyst flow ratio (H2O / catalyst / hour) from 1 (g / g / h) to 100 (g / g / h).

[0103] Item 8. The method according to any one of items 1 to 7, wherein the second flushing medium comprises from 0.1*10 -3 (mol / g / h) to 100*10 -3 The nitrogen to catalyst flow ratio (N2 / catalyst / hour) is (mol / g / h).

[0104] Item 9. The method of any one of items 1-8, wherein the gas phase of the first flush medium comprises from about 0.1% to about 30% oxygen by volume.

[0105] Item 10. The method according to any one of items 1 to 9, wherein the gas 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.

[0106] Item 11. The method according to any one of items 1-10, wherein the gas phase of the first flushing medium comprises at least 90% by volume of air.

[0107] Item 12. The method according to any one of items 1-11, wherein the gas phase of the second flushing medium comprises at least 99% by volume nitrogen.

[0108] Item 13. The method according to any one of items 1-12, wherein the gas phase of the second flushing medium is substantially free of oxygen.

[0109] Item 14. The method according to any one of items 1 to 13, wherein the oxygen-containing hydrocarbon is a sugar.

[0110] Item 15. The method according to any one of items 1 to 14, wherein the hydrogenation catalyst comprises a support and an active metal.

[0111] Item 16. The method according to Item 15, wherein the hydrogenation catalyst is ruthenium supported on carbon (Ru / C).

[0112] Item 17. A method for producing a regenerated hydrogenation catalyst from a contaminated 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 a contaminated hydrogenation catalyst, wherein the contaminated hydrogenation catalyst comprises an amount of sulfur derived from the at least one sulfur-containing impurity of the feedstream, and The contaminated hydrogenation catalyst is subjected to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flush medium for an air treatment duration to produce an air-treated catalyst, wherein the first flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a gas phase comprising oxygen, and (b) contacting the air-treated catalyst with a second flush medium for a nitrogen treatment duration to produce a nitrogen-treated catalyst, wherein the second flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a vapor phase comprising at least 90% by volume nitrogen; The amount of sulfur in the nitrogen-treated hydrogenation catalyst is reduced relative to the amount of sulfur in the contaminated hydrogenation catalyst.

[0113] Item 18. The method according to Item 17, comprising subjecting the nitrogen-treated catalyst to a set of consecutive regeneration cycles of operation (a) and operation (b), each operation having a corresponding treatment duration, to produce a regenerated hydrogenation catalyst.

[0114] Item 19. The method according to any one of items 17-18, wherein the air treatment duration is at least 30 minutes.

[0115] Item 20. The method according to any one of items 17 to 19, wherein the nitrogen treatment duration is at least 30 minutes.

[0116] Item 21. A method according to any one of items 17-20, wherein the air treatment duration is at least 30 minutes, wherein the nitrogen treatment duration is at least 4 hours, and wherein the amount of sulfur in the regenerated hydrogenation catalyst is reduced by at least 5% relative to the amount of sulfur in the contaminated hydrogenation catalyst.

[0117] Item 22. The method of any one of items 17-21, wherein the regeneration cycle is performed at a temperature of from about 70°C to about 120°C.

[0118] Item 23. The method of any one of items 17-22, wherein the regeneration cycle is conducted at a pressure of from about 50 psig to about 200 psig.

[0119] Item 24. The method of any one of items 17-23, wherein the feed stream has an amount of sulfur of at least 0.1 ppm.

[0120] Item 25. The method of any one of items 17-24, wherein the gas phase of the first flush medium comprises from about 0.1% to about 30% oxygen by volume.

[0121] Item 26. The method according to any one of items 17 to 25, wherein the gas 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.

[0122] Item 27. The method according to any one of items 17-26, wherein the gas phase of the first flushing medium comprises at least 90% air by volume.

[0123] Item 28. The method according to any one of items 17-27, wherein the gas phase of the second flushing medium comprises at least 99% by volume nitrogen.

[0124] Item 29. The method according to any one of items 17-28, wherein the gas phase of the second flushing medium is substantially free of oxygen.

Claims

1. A method for hydrogenating biomass, the method comprising: Containing water and oxygen-containing hydrocarbon (C 2+ O 1+ ) with hydrogen in the presence of a hydrogenation catalyst for a hydrogenation duration to produce a first hydrogenated product stream and contaminated hydrogenation catalyst; subjecting the contaminated hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flush medium for an air treatment duration to produce an air-treated catalyst, wherein the first flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a gas phase comprising oxygen, and (b) contacting the air-treated catalyst with a second flush medium for a nitrogen treatment duration to produce the regenerated hydrogenation catalyst, wherein the second flush medium comprises liquid water measured at 25° C. and 1 atmosphere, and a vapor phase comprising at least 90% by volume nitrogen; as well as The feed stream is catalytically reacted with hydrogen in the presence of the regenerated hydrogenation catalyst to further produce a second hydrogenated product stream.

2. The method according to claim 1, wherein the air treatment duration is at least 30 minutes.

3. The method according to any one of claims 1-2, wherein the nitrogen treatment duration is at least 30 minutes.

4. The method of any one of claims 1-3, wherein the regeneration cycle is performed at a temperature of from about 70°C to about 120°C.

5. The method of any one of claims 1-4, wherein the regeneration cycle is conducted at a pressure of from about 50 psig to about 200 psig.

6. The method according to any one of claims 1 to 5, wherein the first flushing medium comprises from 0.1 to 10 -3 (mol / g / h) to 100 * 10 -3 The oxygen to catalyst flow ratio (O2 / catalyst / hour) is (mol / g / h).

7. The method of any one of claims 1 to 6, wherein the first flush medium and / or the second flush medium comprises a water to catalyst flow ratio (H2O / catalyst / hour) of from 1 (g / g / h) to 100 (g / g / h).

8. The method according to any one of claims 1 to 7, wherein the second flushing medium comprises from 0.1 to 10 -3 (mol / g / h) to 100 * 10 -3 The nitrogen to catalyst flow ratio (N2 / catalyst / hour) is (mol / g / h).

9. The method of any one of claims 1-8, wherein the gas phase of the first flush medium comprises from about 0.1% to about 30% oxygen by volume.

10. The method of any one of claims 1-9, wherein the gas phase of the first flush medium further comprises an inert gas selected from the group consisting of nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide, and combinations thereof.

11. The method of any one of claims 1 to 10, wherein the gas phase of the first flush medium comprises at least 90% by volume of air.

12. The method according to any one of claims 1 to 11, wherein the gas phase of the second flush medium comprises at least 99% by volume nitrogen.

13. The method of any one of claims 1 to 12, wherein the gas phase of the second flush medium is substantially free of oxygen.

14. The method of any one of claims 1-13, wherein the oxygenated hydrocarbon is a sugar.

15. The process of any one of claims 1 to 14, wherein the hydrogenation catalyst comprises a support and an active metal.

16. The method of claim 15, wherein the hydrogenation catalyst is ruthenium supported on carbon (Ru / C).

17. A method for producing a regenerated hydrogenation catalyst from a contaminated 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 the contaminated hydrogenation catalyst, wherein the contaminated hydrogenation catalyst comprises an amount of sulfur derived from the at least one sulfur-containing impurity of the feedstream, and subjecting the contaminated hydrogenation catalyst to a regeneration cycle to produce a regenerated hydrogenation catalyst, the regeneration cycle comprising: (a) contacting the catalyst with a first flush medium for an air treatment duration to produce an air-treated catalyst, wherein the first flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a gas phase comprising oxygen, and (b) contacting the air-treated catalyst with a second flush medium for a nitrogen treatment duration to produce a nitrogen-treated catalyst, wherein the second flush medium comprises liquid water measured at 25° C. and 1 atmosphere and a vapor phase comprising at least 90% by volume nitrogen, wherein the amount of sulfur in the nitrogen-treated hydrogenation catalyst is reduced relative to the amount of sulfur in the contaminated hydrogenation catalyst.

18. The method of claim 17, comprising subjecting the nitrogen-treated catalyst to a set of consecutive regeneration cycles of operation (a) and operation (b), each operation having a corresponding treatment duration, to produce the regenerated hydrogenation catalyst.

19. The method according to any one of claims 17-18, wherein the air treatment duration is at least 30 minutes.

20. The method according to any one of claims 17 to 19, wherein the nitrogen treatment duration is at least 30 minutes.

21. The process of any one of claims 17-20, wherein the air treatment duration is at least 30 minutes, wherein the nitrogen treatment duration is at least 4 hours, and wherein the amount of sulfur in the regenerated hydrogenation catalyst is reduced by at least 5% relative to the amount of sulfur in the contaminated hydrogenation catalyst.

22. The method of any one of claims 17-21, wherein the regeneration cycle is performed at a temperature of from about 70°C to about 120°C.

23. The method of any one of claims 17-22, wherein the regeneration cycle is conducted at a pressure of from about 50 psig to about 200 psig.

24. The process of any one of claims 17-23, wherein the feed stream has an amount of sulfur of at least 0.1 ppm.

25. The method of any one of claims 17-24, wherein the gas phase of the first flush medium comprises from about 0.1% to about 30% oxygen by volume.

26. The method of any one of claims 17-25, wherein the gas phase of the first flush medium further comprises an inert gas selected from the group consisting of nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide, and combinations thereof.

27. The method of any one of claims 17-26, wherein the gas phase of the first flush medium comprises at least 90% air by volume.

28. The method of any one of claims 17-27, wherein the gas phase of the second flush medium comprises at least 99% by volume nitrogen.

29. The method of any one of claims 17-28, wherein the gas phase of the second flush medium is substantially free of oxygen.

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