 SYSTEMS, METHODS AND APPARATUSES FOR

HSCHER-TROPSCH CATALYST REGENERATION

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[00011 Not applicable.

RELATED CASES

[0002] This application claims priority from US Provisional Patent Application No. 61/800,376 filed on March 15, 2013. The assignee of this application filed the following related provisional patent applications on March 15, 2013: (1) US Provisional Application No. 61/798,981, entitled "Systems, Methods and Apparatuses for a Compact Reactor" and having assignee patent file number GI-0006-US-P01; (2) US Provisional Application No. 61/799,485, entitled "Systems, Methods and Apparatuses for Use of Organic Rankine Cycles" and having assignee patent file number GI-0007-US-P01; (3) US Provisional Application No. 61/799,825, entitled ''Systems, Methods and Apparatuses for a Shaped- Finned Reactor" and having assignee patent file number Gi~0QQ8-US~P01; and (4) LIS Provisional Application No. 61/800,090, entitled "Systems, Methods and Apparatuses for a Compact Reactor with Finned Panels" and having assignee patent file number GI-0Q25-US- P0I, all of which are incorporated herein by reference in their entireties. The assign ee of this application is filing on even date herewith the following related PCT patent applications:

PCX Application No. entitled "Systems, Methods and Apparatuses for Use of

Organic Rankine Cycles" and having assignee patent file number GI-0007-WO-01, and claiming priority from the above-mentioned US Provisional Application Nos. 61/799,485 and

61/799,825); and PCT Application No. , entitled, entitled "Systems, Methods and

Apparatuses for a Compact Reactor with Finned Panels," having assignee patent file number GI-0025-WQ-01 and claiming priority from the above-mentioned US Provisional Application No. 61/800,090.

BACKGROUND

Field of the Invention

{00031 The present disclosure relates to systems, methods, and apparatuses for regenerating Fischer-Tropsch catalyst. Specifically, the present disclosure relates to systems, methods, and apparatuses for regenerating Fischer-Tropsch catalyst via solvent washing.

Background of the Invention [0004] The Fischer-Tropsch (or "Fischer Tropsch.," "F-T" or "FT") process (or synthesis or conversion) involves a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen (known as reformed gas, synthesis gas, or "syngas") into liquid hydrocarbons (called "liquid FT hydrocarbons" herein). The process was first developed by German chemists Franz Fischer and Hans Tropsch in the 1920's. The FT conversion is a catalytic and exothermic process. The FT process is utilized to produce petroleum substitutes, typically from, carbon-containing energy sources such as coal, natural gas, hiomass, or carbonaceous waste streams (such as municipal solid waste) thai are suitable for use as synthetic fuels, waxes and/or lubrication oils. The carbon-containing energy source is first converted into a reformed gas (or synthetic gas or syngas), using a syngas preparation unit in what may be called a syngas conversion. Once the syngas is created, the syngas is used as an input to an FT reactor having an FT catalyst to make the liquid FT hydrocarbons in a Fischer-Tropsch synthesis (or FT synthesis or FT conversion). Depending on the type of FT reactor, the FT conversion of the syngas to liquid FT hydrocarbons takes place under appropriate operating conditions.

[0005] Depending on the physical form of the carbon-containing energy source, syngas preparation may involve technologies such as steam methane reforming, gasification, carbon monoxide shift conversion, acid gas removal gas cleaning and conditioning. These steps convert the carbon-containing energy source to simple molecules, predominantly carbon monoxide and hydrogen, which are the active ingredients of synthesis gas. Th e synthesis gas will also inevitably contain carbon dioxide, water vapor, methane, nitrogen, impurities deleterious to catalyst operation such as sulfur and nitrogen compounds are often present in trace amounts and are removed to very Sow concentrations as part of synthesis gas conditioning.

[0006] Turning to the syngas conversion step, to create the syngas from natural gas, for example, methane in the natural gas reacts with steam and oxygen in a syngas preparation unit to create syngas. The syngas compr ses principally carbon monoxide, hydrogen, carbon dioxide, water vapor and unconverted methane. When partial oxidation is used to produce the synthesis gas, typically the syngas contains more carbon monoxide and less hydrogen man is optimal and consequently, steam is added to the react with some of the carbon monoxide in a water-gas shift reaction. The water gas shift reaction can be described as: CO + ¾{? ¾ H ₂ CQ ₂ (.1) [0007] Therrnodynaniieaiiy, there is an equilibrium between the forward and the backward reactions. That equilibrium is determined by the concentration of the gases present. OOGSf Once the syngas is created and conditioned, the syngas is used as an input to an FT reactor having an FT catalyst to make the liquid FT hydrocarbons in a Fischer-Tropscii synthesis (or FT synthesis or FT conversion). Depending on the type of FT reactor, the FT conversion of the syngas to liquid FT hydrocarbons takes place under appropriate operating conditions. The Fischer-Tropsch (FT) reactions for the FT conversion of the syngas to the liquid FT hydrocarbons may be siniplistically expressed as:

(2n+ 1) Ha + n CO→ C„H ₂ n+2 + n H ₂ 0, (2) where 'n' is a positive integer.

[0009] In addition to liquid FT hydrocarbons, the Fischer-Tropsch synthesis also commonly produces gases (called "FT tail gases" herein) and water (called "FT water ^' " herein). The FT tail gases typicaily contain CO (carbon monoxide), CO? (carbon dioxide), H ₂ (hydrogen), light hydrocarbon molecules, both saturated and unsaturated, typically having carbon values ranging from C[ to C ₄ , and a small amount of light oxygenated hydrocarbon molecules such as methanol. Typically, FT tail gases are mixed in a facility's fuel gas system for use as fuel. The FT water will typically include dissolved oxygenated species, such as alcohols, and light hydrocarbons, which are typically removed prior to disposal of the FT water.

[0010] The FT reaction is performed in the presence of a catalyst, called a Fischer-Tropsch catalyst ("FT catalyst"). Unlike reagents, a catalyst does not participate in the chemical reaction and is not consumed by the reaction itself. In addition, a catalyst may participate in multiple chemical transformations. Catalytic reactions have a lower rate-limiting free energy of activation than the corresponding un-eaialyzed reaction, resulting in higher reaction rate at the same temperature. However, the mechanistic explanation of catalysis is complex. Catalysts may affect the reaction environment favorably, or bind to the reagents to polarize bonds, e.g. acid catalysts For reactions of eafhonyl compounds, or ^' form specific intermediates that are not produced naturally, such as osmate esters in osmium tetroxide-catalyzed dihydroxylation of alkenes, or cause lysis of reagents to reactive forms, such as atomic hydrogen in catalytic hydrogenation.

[0011] A variety of catalysts are utilized to catalyze the Fischer-Tropsch synthesis, with cobalt- based and iron-based catalysts being the most prevalent, hi addition, most FT catalysts are either supported or precipitated. If an FT catalyst is supported, a metal-based catalyst is deposited upon the interior of a metal structure resembling a tunnel, having a mouth or "pore." The structure that the T catalyst is deposited upon and the ^' FT catalyst pores are very small. The FT catalysts may deactivate by a variety of mechanisms. Reasons for Fischer-Tropsch catalyst deactivation include, without limitation: the oxidation of the active metal of the FT catalyst, e.g. oxidation of cobalt to cobalt oxide; plugging of the FT catalyst pores with heavy hydrocarbons; reaction of the active metal, such as cobalt; and blocking of active sites on the surface of the FT catalyst.

[0012] Several FT catalyst regeneration procedures are practiced. Such FT catalyst regeneration procedures can be differentiated by the presence or absence of an oxidation step during regeneration. A first type of FT catalyst regeneration procedure is based solely on hydrogen used as a regeneration gas ("hydrogen regeneration procedure(s)"). hi hydrogen regeneration procedures, the temperature may be varied, as well as the gas lineal velocity (i.e. the GLV) and/or the purity of the regeneration gas. A goal in a hydrogen regeneration procedure is to remove the hydrocarbon by desorption from the FT catalyst pellet by boiling the hydrocarbons and stripping the hydrocarbons away from the FT catalyst. Typically, not all the hydrocarbon is removed by the boiling and stripping steps. Following boiling and stripping, the remainder of the hydrocarbons is typically thermally and/or catalytically cracked by the same FT catalyst in the presence of hydrogen. The heavier the hydrocarbon mixture remaining with the FT catalyst, the higher the temperature will need to be during the thermal or catalytic cracking to remove the remaining hydrocarbons. The higher the molecular weight of the hydrocarbon mixture, the less boiling and the more cracking that will be occurring, Part of this process may undesirably leave carbon deposited in the catalyst pores. Once the hydrocarbon mixture has been removed, the exposed metal oxides can be reduced and the FT catalyst can thus be made catalytically active for former Fischer-Tropsch synthesis.

[0013] A second conventional catalyst regeneration procedure includes an oxidation step that burns carbon remaining on the catalyst and creates an oxide of the active metal. The oxidation step generally involves a diluted air stream. The oxidation step is typically followed by a reduction step with hydrogen, in the reduction step, whic is usually performed at higher temperatures than oxidation and dry hydrogen, the metal oxides are reduced and the FT catalyst can thus be made catalytically active for further Fischer-Tropsch synthesis.

[0014] The use, during regeneration, of severe regeneration conditions, such as elevated temperatures, can prove detrimental ^' to the FT catalyst. Severe regeneration conditions may reduce the life of the FT catalyst and/or may reduce the FT catalytic activit regained by the regenerated FT catalyst. Damage caused by severe regeneration conditions can include, for example, pore collapse due to sintering, reducing the surface area (e.g. the BET surface area), and/or agglomeration of crystallites, also resulting in ^" loss of active surface in the FT catalyst. [0015] Accordingly, there are needs in the art for novel systems and methods for regenerating FT catalyst that enable the use of less extreme regeneration conditions. Desirably, such systems and methods enable catalyst regeneration via the use of readily available materials, such as FT liquid hydrocarbons.

SUMMARY

[0016] These and other embodiments, features and advantages will be apparent in the following detailed description and drawings.

foonj The present disclosure includes a method of regenerating a Fischer-Tropsch ("FT") catalyst that is at least partially spent through having been utilized to produce FT hydrocarbons via FT synthesis in an FT reactor. The method includes the steps of washing the FT catalyst to be regenerated with a first wash fluid. The FT catalyst to be regenerated comprises pores, and at least a fraction of the pores contain a first mixture of hydrocarbons, The first wash fluid comprises at least one hydrocarbon, and the a verage molecular weight of the at least one hydrocarbon of the first wash fluid is less than the average molecular weight of the hydrocarbons in the first mixture of hydrocarbons. The method also includes contacting the washed FT catalyst with a gas comprising hydrogen.

[ooisj The present disclosure includes a system for regenerating a spent FT catalyst. The system includes an FT reactor configured to produce FT product hydrocarbons and an FT vapor, via FT synthesis. The system also includes a vessel configured for washing of spent FT catalyst with one or more wash fluids, at least one apparatus selected from the group consisting of a product upgrading apparatus configured to provide, from the FT product hydrocarbons, FT naphtha, FT diesel, or both; a first condenser configured to condense a medium FT liquid (MFTL) from the FT vapor, thus providing an MFTL and an uncondensed vapor, a second condenser configured to condense a light FT liquid (LFTL) from the uncondensed vapor, thus providing an LFTL and a second uncondensed vapor; and one or more recycle lines. The recycle lines may be selected from the group consisting of recycle lines flmdly connecting the first condenser with the vessel, whereby at least a portion of the MFTL may be introduced thereto as wash fluid, recycle lines fluid!y connecting the second condenser with the vessel, whereby at least a portion of the LFTL may be introduced thereto as wash fluid, and recycle lines fluidly connecting the product upgrading apparatus with the vessel whereby FT diesel, the FT naphtha, or both may be introduced thereto as a wash fluid. [0019] The present disclosure includes an apparatus for regenerating a spent Fischer-Tropsch (FT) catalyst. The apparatus includes an FT reactor configured to produce FT product hydrocarbons and an FT vapor, via FT synthesis and configured for washing of the spent FT catalyst sequentially with a first wash fluid and a second wash fluid, a first condenser configured to condense a medium FT liquid (MFTL) from the FT vapor, thus providing an FTL and an uncondensed vapor; a second condenser configured to condense a light FT liquid (LFTL) from the uncondensed vapor, thus providing an LFTL and a second uncondensed vapor; and a first recycle line fluidly connecting the first condenser with the FT reactor. At least a porti n of the MFTL may be introduced to the FT reactor as the first wash fluid. A second recycle line fluidly connects the second condenser with the FT reactor, whereby at least a portion of the LFTL may be introduced thereto as the second wash fluid.

[0020] These and other embodiments, features and advantages will be apparent in the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

| 02l] For a more detailed description of the present invention, reference will now be made to the accompanying drawings, wherein:

[0022] Figure 1 is flow diagram of a Fischer-Tropsch catalyst regeneration method according to an embodiment of this disclosure;

|0023] Figure 2 is a plot of the carbon number distribution of a typical straight run hydrocarbon cut collected at approximately 30°C and suitable for use in Fischer-Tropsch catalyst regeneration according to embodiments of this disclosure, and

[0024] Figure 3 is a schematic of a Fischer-Tropsch catalyst regeneration system according to an embodiment, of this disclosure.

NOTATION AND NOMENCLATURE

[0025J As used herein, the term regeneration is meant to comprise any of the steps taken to prepare spent Fischer-Tropsch catalyst for reuse in Fischer-Tropsch synthesis. Thus, "regenerati n" may include removal of hydrocarbons from the spent catalyst via, for example, draining of the hydrocarbons therefrom, stripping of hydrocarbons from the spent catalyst, for example, via contact with hydrogen, removal of carbon deposits via oxidation with an oxidation gas comprising oxygen, reactivation of catalyst via contact with an activation gas, for example, via contact with an activation gas containing hydrogen, or any combination of one or more thereof. Thus, as used herein, the term "regeneration" is meant to be inclusive of conventional rejuvenation, regeneration, activation and re-activation.

[0026] When it is stated herein that a hydrocarbon or a hydrocarbon mixture (e.g. diesel or an MFTL) may be used "as a wash fluid," it is to be understood that the hydrocarbon or a hydrocarbon mixture may be utilized as the only component of the wash fluid or may make up one component of a multi-component wash fluid. That is, the wash fluid may consist essentially of the hydrocarbon or a hydrocarbon mixture or the wash fluid may comprise the hydrocarbon or a hydrocarbon mixture.

[0027] The phrase "straight run" indicates that hydrocarbons produced by FT synthesis have been separated, but not treated to alter the composition thereof, i.e. the cut has not been hydrotreated or cracked.

DETAILED DESCRIPTION

| ^' 002Sj Overview. Herein disclosed are systems, methods and apparatuses for regenerating Fischer-Tropsch catalysts. Although the process(es) as described herein may be suitable and advantageous for regenerating a variety of Fischer-Tropsch catalysts, the systems, methods and appar atuses may be particularly useful for regenerating a cobali-based Fischer-Tropsch catalyst. According to one or more embodiments of the present disclosure, a lower molecular weight fluid or successively lower molecular weight fluids are utilized to wash the FT catalyst to be regenerated, thus removing heavier hydrocarbons from the pores of the FT catalyst prior to further treatment, such as reduction, oxidation and/or further reduction. Such replacement of the material within the pores prior to reduction and/or oxidation reduces the severity (e.g. the temperature) at which the reduction and/or oxidation may need to be performed. This may result in an enhanced FT catalyst life, improved regenerated FT catalyst performance (e.g. activity), and/or a decrease in the severity or an elimination of the u eed for oxi dation of the FT catalyst prior to reuse.

[0029] The systems, methods and apparatuses of this disclosure may be utilized to remove relatively heavy hydrocarbons that remain in the pores of a catalyst after Fischer-Tropsch synthesis has stopped. This may be effected by a (e.g. sequential) washing with one or more hydrocarbons or mixtures of hydrocarbons. One or more embodiments of the present invention may comprise a single wash with one or more hydrocarbons or mixtures of hydrocarbons. One or more embodiments of the present invention may comprise a plurality of sequential washes, each wash one including use of one or more hydrocarbons or mixtures of hydrocarbons. In either case, each wash may be performed with a wash fluid having a ower average molecular weight of hydrocarbon(s) than the majority of the hydrocarbons remaining trapped in the pores of the catalyst prior to that wash. Each wash may be performed at a wash temperature at which at least a fraction of the hydrocarbon (or hydrocarbon mixture) of the wash fluid remains liquid, in one or more embodiments of the present disclosure, each wash is performed at a wash temperature at which at least 80% of the wash fluid remains in a liquid form.

{0030] The washing of relatively heavy hydrocarbons with relatively lighter ones prior to the catalyst regeneration via reduction and/or oxidation may allow the utilization of lower temperature(s) in the regeneration process, since lighter hydrocarbons are removable at lower temperatures due to the lower boiling points and lower ignition points of lighter hydrocarbons relative to the boiling and ignition points of heavier hydrocarbons.

[0031] As mentioned above, one or more embodiments of the FT catalyst regeneration procedure of the present disclosure may enable a reduction in the severity of the regeneration conditions (e.g. temperature, duration, and/or specific regeneration processes) utilized, i.e. regeneration via reduction only versus reduction and oxidation). By reducing the severity of the regeneration conditions, the FT catalyst may last longer (i.e. have a longer catalyst life) and/or a may be regenerated to a higher activity level. The disclosed FT catalyst regeneration procedure(s) may reduce or eliminate the degree of damage to the catalyst relative to conventional regeneration in the absence of the disclosed washing. For example, the degree of damage may be reduced (and the FT catalyst activity increased) by a reduction and/or elimination of pore collapse that may be caused by sintering (which reduces the BET area of the catalyst), and increase of the agglomeration of crystallites that may result in a loss of dispersion of the active metal on the catalyst surface. Additionally or alternatively, the hydrocarbon removal and/or activation procedure (e.g. the regeneration via stripping and/or reduction) may take less time if the heavier hydrocarbons are removed by lighter ones as per this disclosure. In one or more embodiments, the disclosed systems, methods and apparatuses provide for a reduction ^" in the amount of carbon ^' deposited on the catalyst surface during regeneration ^' (e.g. during reduction). Such a reduction in the amount of carbon deposits may provide for regeneration of the FT catalyst in the absence of oxidation with a reduced amount of hydrocarbons (i.e. less time for and/or reduced severity' of oxidation) relative to regeneration in the absence of the herein disclosed ^''" fluid ^' ash(es).

[0032] FlG. 1 is a flow diagram of a Fischer-Tropsch catalyst regeneration method according to one or more embodiments of the present disclosure. FlG. ί depicts providing an FT catalyst to be regenerated 10, washing the FT catalyst to be regenerated with a first wash -fluid ^' 20 an ^' d subjecting the washed ^' FT catalyst to one or more additional regeneration steps (such as reduction and/or oxidation) 40. As indicated in FIG. I, one or more embodiments of the present disclosure may further comprise washing die once washed catalyst from 20 with one or more additio al washes, each of which may include one or a combination of wash fluids at 30. Each of these steps are described in more detail below .

[0033] Providing Fischer-Tropsch Cai lyst to be Regenerated 10, As noted above, the FiG. 1 depicts providing 10 a Fischer-Tropsch caialyst to be regenerated. As noted in FIG. 1, the step of providing 10 an FT catalyst to be regenerated may further comprise producing 11 FT wax hydrocarbons in the presence of the FT catalyst, condensing 12 medium Fischer-Tropsch liquids (IvfFTL), condensing 13 light Fischer-Tropsch liquids (LFTL), or a combination of two or more thereof.

[0034] Referring to step l lof FiG. 1, the FT catalyst requiring regeneration is provided, at least in part, by producing the FT hydrocarbons in the presence the FT catalyst, until such time as the FT caialyst is ready for regeneration (i.e. until the FT catalyst is 'spent'). The FT hydrocarbons may be produced 11 using the FT catalyst (to provide FT catalyst to be regenerated) via any methods known in the art. That is, any known FT catalyst may be utilized in the FT synthesis, whereby the FT catalyst is spent and regeneration thereof is needed to regain adequate activity, in one or more embodiments of the present disclosure, the FT catalyst comprises a cobalt-based FT catalyst, in one or more embodiments of the present disclosure, ihe FT catalyst compri ses an iron-based catalyst, In one or more embodiments of the present disclosure, the FT caialyst comprises a supported FT catalyst, in one or more embodiments of the present disclosure, the FT catalyst comprises a supported, cobalt-based FT catalyst, hi one or more embodiments of the present disclosure, the FT catalyst comprises a supported, iron-based ^' FT catalyst. The FT catalyst may have been utilized to produce the FT hydrocarbons via FT synthesis via any methods and/or systems known in the art. For example, the FT catalyst requiring regeneration may have been utilized to produce the FT hydrocarbons via a conversion of a synthesis gas (i.e. a gas comprising hydrogen and carbon monoxide) in an FT synthesis reactor. In one or more embodiments of the present disclosure, the FT catalyst to be regenerated was utilized to produce the FT hydrocarbons via an FT conversion of a syngas in a slurry bed FT synthesis reactor, hi one or more embodimenis of the present disclosure, the FT catalyst to be regenerated was utilized ^' to produce the FT hydrocarbons via an FT conversion of a syngas in a fixed bed FT synthesis reactor. As noted hereinabove, one or more embodiments of the present disclosure may be particularly suitable for the regeneration of a cobalt-based FT caialyst previously utilized for FT synthesis in a fixed bed reactor. Suitable FT reactors are known to those of skill in the aft. in one or more embodiments of the present disclosure, the regeneration vessel comprises an FT reactor, in one or more embodiments of ihe present disclosure., the regeneration vessel comprises an FT reactor thai comprises a fixed bed reactor. A suitable fixed bed reactor may, in one or more embodiments of the present disclosure, contain tubes having an inner diameter in the range of from about ½" to about 2". In one or more embodiments of the present disclosure, the regenerati on vessel comprises a vessel which is not an FT reactor.

[0035] Providing the FT catalyst to be regenerated 10 may thus further comprise producing ii the Fiseher-Tropsch hydrocarbons via a Fiseher-Tropsch conversion of a synthesis gas in a Fischer-Tropsch reactor containing unspent FT catalyst. The specific FT synthesis conditions may depend on the specific FT catalyst utilized for the FT conversion process. In one or more embodiments of the present disclosure, the FT catalyst to be regenerated comprises a cobalt-based FT catalyst that, prior to regeneration as described herein, was utilized in a Fischer-Tropsch conversion carried out at a temperature in the range of from about 180°C to about 250°C, a temperature in the range of from about 190°C to about 230°C, or a temperature in the range of from about 190°C to about 215°C. in one or more embodiments of the present disclosure, the FT catalyst to be regenerated comprises a cobalt-based FT catalyst that, prior to regeneration as described herein, was utilized in a Fischer-Tropsch conversion earned out at a pressure in the range of from about 200 psig to about 650 psig, from about 300 psig to about 550 psig, or from about 350 psig to about 450 psig. in one or more embodiments of the present disclosure, the FT catalyst to be regenerated comprises a cobalt-based FT catalyst that, prior to regeneration as described herein, was utilized in a Fischer-Tropsc conversion carried out with a synthesis gas feed comprising a molar ratio of hydrogen to carbon monoxide in the range of from about 2.5: 1 to about 1: 1, from about 2:3 to about 1 : 1, or from about 2.0: 1 to about 1.5: 1. In one or more embodiments of the present disclosure, the FT catalyst to be regenerated comprises a cobalt-based FT catalyst that, prior to regeneration as described herein, was utilized in a Fischer-Tropsch conversion carried out with a GLV of a synthesis gas feed in the range of from about Ϊ 0 to about 40 cm/s, from about 12 to about 35 cm/s, or from about 18 to about 30 cm/s.

[0036] to one or more embodiments of the present disclosure, providing an FT catalyst to be regenerated at 10 may further comprise shutting down the FT synthesis and/or removing the Fischer-Tropsch product hydrocarbons from the Fischer-Tropsch reactor. For example, removing Fischer-Tropsch product hydrocarbons from the Fischer-Tropsch reactor may comprise draining bulk liquids (/ ^' . e. Fischer-Tropsch product hydrocarbons) from the Fischer- Tropsch reactor, prior to subjecting the FT catalyst to be regenerated to washing at 20 and/or 30, The shutdown procedure may comprise cooling down the Fischer-Tropsch reactor and its contents.

|0037] Shutting down the FT synthesis may comprise passing an inert gas (such as, without limitation, gas comprising nitrogen) therethrough to make the environment mert. The process of passing inert gas therethrough may serve to strip lighter components from the FT catalyst but may leave heavier components coating and within the pores of the FT catalyst particles. In one or more embodiments of the present disclosure, providing an FT catalyst to be regenerated at 10 may further comprise purging the Fischer- Tropsch reactor from which product FT hydrocarbons have been removed {e.g. drained) with inert gas. A suitable inert gas comprises nitrogen, carbon dioxide, methane, or a combination thereof.

[0038] In one or more embodiments of the present disclosure, providing a catalyst to be regenerated at 10 further comprises coolmg the temperature of the Fischer-Tropsch reactor from a Fischer-Tropsch synthesis temperature to a first washing temperature.

10039] in one or more embodiments of tire present disclosure, providing a catalyst to be regenerated at 10 further comprises removing the FT catalyst to be regenerated from the FT reactor to a second vessel. Alternatively, the FT catalyst to be regenerated may be left in the FT reactor for regeneration in situ.

[(5040] As mentioned above and depicted by FIG. 1, producing the FT hydrocarbons at 11 may be associated wim condensing FTL 12 from a vapor obtained during FT synthesis, thus providing MFTL and a first uncondensed vapor, and/or condensing LFTL 13 from the first uncondensed vapor, thus providing an LFTL and a second uncondensed vapor. According to one or more embodiments of the present disclosure, the FT hydrocarbon fractions produced during the FT synthesis may include FT wax (or "heavy Fischer-Tropsch liquids" or "HFTL"), MFTL, LFTL, or a combination of any two or more thereof, FIG. 2 illustrates differences in carbon number distributions for MFTL, LFTL and FT wax. FiC ^~ 2 is a plot of a carbon number distribution of a typical straight run hydrocarbon cut collected at typical FT conditions and suitable for use in Fischer-Tropsch catalyst regeneration. In FIG. 2, a "mol. fraction" (molecular fraetion(s)) 110 on the y-axis are plotted against carbon numbers 100 on the X-axis for FT wax., MFTL and LFTL. The carbon number distribution for FT wax is depicted with a solid line 120. The carbon number distribution for MFTL is depicted with a doited line 130. The carbon number distribution for LFTL is depicted with a dashed line 140. As will be apparent to those of skill in the art and from FIG. 2, the average molecular weight of the FT wax is greater than the average molecular weight of the MFTL, and the average molecular weight of the MFTL is greater than the average molecular weight of the LFTL. [0041 j As noted further herein, an MFTL obtained during the FT synthesis at 10 may be utilized as first wash fluid or a component thereof. Similarly, an LFTL obtained during the FT synthesis at 10 may be utilized as second (or subsequent) wash fluid or as a component thereof, in embodiments, an MFTL is condensed at a temperature in the range of from about 100°C to about 150°C, from about i05 ^c C to about 145°C, or from about 110°C to about 140 ^C C. In one or more embodiments of the present disclosure, the MFTL comprises primarily paraffins, hi one or more embodiments of the present disclosure, an LFTL is condensed at typical FT pressures and at a temperature i the range of from about 20 ^C C to about 60°C, from about 25°C to about 55°C, or from about 30°C to about 50°C, in one or more embodiments of the present disclosure, the LFTL comprises primarily paraffins.

[0042| In one or more embodiments of the present disclosure in which an MFTL is utilized as a first wash, the composition of the MFTL- is relatively similar/close to the FT wax composition, and thus the FT wax is substantially soluble in the MFTL. In one or more embodiments of the present disclosure in which an LFTL is utilized as a second wash, the composition of the LFTL may be relatively similar/close to the composition of the MFTL, and thus the MFTL is substantially soluble in the LFTL.

[0043] in one or more embodiments of the present disclosure, an FT wax (which may be the first mixture of hydrocarbons present in the pores of the unwashed FT catalyst to be regenerated) has an average molecular weight in the range of from about 200 to about 1120, from about 220 to about 423, or from about 250 to about 350, in one or more embodiments of the present disclosure, the MFTL and/or the first wash fluid (which may be or may comprise MFTL) has an average molecular weight in the range of from about 113 to about 320, from about 170 to about 290, or from about 200 to about 253. In one or more embodiments of the present disclosure, the LFTL and/or the second wash fluid (which may be or may comprise LFTL) has an average molecular weight ^" in the range of fiorn about 70 to about 211, from about 100 to about 225, or from about 112 to about 240.

[0044) In one or more embodiments of the present disclosure, the FT wax has an average molecular weight of greater than about 282, the MFTL and/or the first wash fluid has an average molecular weight of greater than about 211, and/or the LFTL and/or the second' wash fluid has an average molecular weight of greater than about 113,

[0045] In one or more embodiments of the present disclosure, the FT wax has an average carbon number in the range of from about 10 to about 120, from about 15 to about 100, or from about 18 to about ^" 80. In one or more embodiments of the present disclosure, the MFTL or the first wash fluid has an average carbon number in the range of from about 15 to about 20, from about 16 to about 19, or from about 17 to about 18, In orse or more embodiments of the present disclosure, the LFTL or the second wash fluid has an average carbon number in the range of from about 4 to about 18, from about 5 to about 16, or from about 5 to about 12, in one or more embodiments of the present disclosure, the FT wax has an average carbon num ber of greater than about 15, the MFTL and/or the first wash fluid has an average carbon number of greater than about 10, and or the LFTL and/or the second wash fluid has an average carbon number of greater than about 5.

[0046] Washing FT Catalyst to he Regenerated with a First Wash Fluid at 2& and Optionally Washing with one or more Additional Wash Fluids at 30,

[0047] As illustrated in FlG. 1, one or more embodiments of the present disclosure comprise washing the FT catalyst to be regenerated with a first wash fluid at .20 and may further comprise washing the FT catalyst with one or more additional wash fluids at 30. Thus, one or more embodiments of the present disclosure may comprise any number of washing steps, with each subsequent washing step preferably utilizing a wash fluid having a lower average molecular weight than that of the material in the FT catalyst pores prior to that wash step. That is, preferably, the first wash fluid has a lower average molecular weight than that of the material in the pores of the FT catalyst to be regenerated and the second wash fluid has a lower average molecular weight than that of the material in the pores of the FT catalyst after the first wash. For example, the second wash fluid may have an average molecular' weight less than that of the first wash fluid, since, following the first wash, the average molecular weight of the material in the FT catalyst pores will ^' be both greater than or equal to the average molecular weight of the first wash fluid and less than the average molecular weight of the material that was originally in place within tlie FT catalyst pores before the first wash. Thus, if the average molecular weight of tlie second wash fluid is less than the average molecular weight of the first, wash fluid, the average molecular weight of the second wash fluid will also inherently be less than that of the material remaining in the catalyst pores following tlie first wash. For example, in the event of a third wash with a third wash fluid, the average molecular weight of the third wash fluid will be less than the average molecul ar weight of the material remaining in the pores of the FT catalyst after the second wash. For example, the third wash fluid may have an average molecular weight that is less than that of the second wash fluid, since, following the second wash, the average molecular weight of the material in the FT catalyst pores will be both greater than or equal to the average molecular weight of the second wash fluid and less than the average molecular weight of the material left in the FT catalyst pores after the first wash but before the second wash. Thus, if the average molecular weight of the third wash fluid is less than the average molecular weight of the second wash fluid, the average molecular weight of the third wash fluid will also inherently be less than that of the material remaining hi the catalyst pores following the second wash.) The method may employ any number of wash steps.

[0848] The process as described in fee preceding paragraph is conceptually illustrated in FIG. 4. in FIG, 4, which is not drawn to scale, average molecular weight ISO on the Y-axis is plotted versus time 155 on the X-axis. Specifically, average molecular weights of a material left in the Ft catalyst pores 160, a first wash fluid J 65, a second wash fluid 170, and a third wash fluid 175 are depicted over time, in the one or more embodiments of the present disclosure depicted in FJG. 4, during the time period of To to T], FT synthesis is occurring and the FT catalyst used in the FT synthesis process is becoming spent. Other steps to provide the FT catalyst to be regenerated, such as draining the FT products from the FT reactor prior to beginning the regeneration process, may also occur in the time period of To to Ti . The first wash begins at Ti and continues to T ₂ , with the period of the first wash being shaded on the graph of FIG. 4 with a dot pattern. The average molecular weight of the first wash fluid 165 starts at a lesser value than the value of the average molecular weight of the material left in the FT catalyst pores 160 at time equals Tj. During the first wash, hydrocarbons from fee first wash fluid will displace some of the material left in the pores of the FT catalyst. The material from the pores of the FT catalyst displaced during the first wash will become part of lire first wash fluid, thus increasing the average molecular weight 165 of the first wash fluid. Thus, during the first wash, the average molecular weight of the material left in tire pores of the FT catalyst 160 will decrease, while the average molecular weight of the first wash fluid 165 will increase. During the period from T?. to T3, the first wash fluid could be drained from the FT reactor or other regeneration vessel, depending on where the regeneration process is taking place.

jO049j Continuing to refer to FIG. 4, a second wash begins at T3 and continues to T ₄ , with the period of the second wash being shaded on the graph of FIG. 4 with a downward diagonal pattern, The average molecular weight of the second wash fluid 170 starts at a lesser value than (I) the value of the average molecular weight of the first wash fluid 165 and (2) the value of the average molecular weight of the material left in the FT catalyst pores 160 at tune equals Tj. During the second wash, hydrocarbons from the second wash fluid will displace some of the material left in the pores of the FT catalyst. The material from the pores of the FT catalyst displaced during the second wash will ^' become part of the second wash fluid, raising the average molecular weight 170 of the second was fluid. Thus, during the second wash, the average molecular weight of the material left in the pores of the FT catalyst 160 will decrease, while the average molecular weight of the second wash fluid 170 will increase. During the period from T ₄ to T5, the second wash fluid could be drained from the FT reactor or oilier regeneration vessel, depending on where the regeneration process is taking place.

[0050] Referring again to FfG. 4, a third wash begins at T¾ and continues to T ₆ , with Hie period of the third wash being shaded on the graph of FIG. 4 with a divot pattern. The average molecular weight of the third wash fluid 175 starts at a lesser value than (1) the value of the average molecular weight of the second wash fluid 170 and (2) th value of the average molecular weight of the material left in the FT catalyst pores 160 at time equals T ₅ . During the third wash, hydrocarbons from the third wash fluid will displace some of the material left in the pores of the FT catalyst. The material from the pores of the FT catalyst displaced during the third wash will become part, of the third wash fluid, thus increasing the average molecular weight 175 of the first third fluid. Thus, during the third wash, the average molecular weight of the material left in the pores of the FT catalyst 160 will decrease, while the average molecular weight of the third wash fluid 175 will increase. During the period from T ₅ to Te, the thir wash fluid could be drained from the FT reactor or other regeneration vessel, depending on where the regeneration process is taking place. Other regeneration steps could further take place,

jiOOSi] in FiG. 4, the increases and decreases in average molecular weight are represented to be linear. This may or may not be the case, as FiG. 4 has been included only to illustrate in relative terms changes in a verage molecul ar weight of the material left in the pores of the FT catalyst 160, the first wash fluid 165, the second wash fluid 170 and the third wash fluid 175. In addition, the average molecular weight of the material left in the pores of the FT catalyst 160 is depicted in FiG. 4 as being stable between washes. This may or may not be the case, depending on what is taking place between washes.

|00S2| Turning back to FiG. 1, in one or more embodiments of the present disclosure, washing the FT catalyst to be regenerated with a first wash fluid 20, optionally washing the washed catalyst from 20 with one or more additional wash fluids at 30 _; subjecting washed catalyst to reduction and/or oxidation at 40 ^" or a combination of two or more thereof are carried out in situ, i.e. in a Fischer-Tropsc reactor utilized to produce FT hydrocarbons at 11. Alternatively, the FT catalyst to be regenerated may be removed from the FT reactor and placed into a second vessel, where the steps of washing the FT catalyst to be regenerated with, a first wash fluid 20, optionally - washing -fhe washed catalyst ^' from 20 with one or more additional wash fluids at 30, subjecting washed catalyst to reduction and/or oxidation at 40, or a combination of two or more thereof are carried out.

{i iS3} The wash fluid(s) may be introduced at or near the top of the washing vessel (e.g. at or near the top of a FT reactor), and drained from the bottom thereof, as will be discussed in more detail with regard to FIG. 3 below. Preferably, at the end of each wash, the majority of the material associated with the FT catalyst (i.e. on the surface and/or within the pores thereof) at the beginning of that wash period becomes part of the wash fluid utilized in that wash. The material removed from the wash vessel with the wash fluid may be monitored until it comprises substantially wash fluid introduced during that stage and/or until no further change is seen in the composition of the drained material.

[0054] Preferably, at least a portion of the hydrocarbons in the pores of the FT catalyst prior to each wash should be soluble in the wash fluid utilized for that wash. Tims, at least a portion of the hydrocarbons in the pores of the FT catalyst to be regenerated should be soluble in the first wash fluid, at least a portion of the hydrocarbons in the pores of the FT catalyst at the end of the first wash should be soluble in any wash fluid utilized hi a second wash, and so on. Desirably, a majority of the material remaining in the pores of the FT catalyst prior to each wash are soluble in the wash fluid utilized for that wash, in one or more embodiments of the present disclosure, a majority of the hydrocarbons present in the pores of the FT catalyst to be regenerated prior to any washing are soluble in the iirst wash fluid. In one or more embodiments of the present disclosure, a second wash is performed and a majority of the hydrocarbons remaining in the pores of the FT catalyst following the first wash (which may be primarily hydrocarbonfs) of the first wash fluid) are soluble in the second wash fluid, Thus, in one or more embodiments of the present disclosure, a majority of the hydrocarbons in a first mixture of hydrocarbons present in the unwashed FT catalyst to be regenerated are soluble in the first wash fluid, in one or more embodiments of the present disclosure, a majority of ^' the ^' hydrocarbons in the pores of the FT catalyst prior to the first wash may not be soluble in the second wash fluid, but are soluble in the first wash fluid.

[0055] The first mixture of hydrocarbons present in the unwashed FT catalyst to be regenerated may comprise Fischer-Tropsch product hydrocarbons (e.g. FT w x that is generally liquid at FT synthesis conditions). For example, the first mixture of hydrocarbons present in the unwashed FT catalyst pores may be similar to the FT wax, the carbon number distribution of which (under conditions previously stated) is depicted in FIG. 2. In one or more embodiments of the present disclosure, pores of the 'unwashed' ^' FT catalyst to ^' be regenerated contain a treatment or wash fluid which has been contacted with the FT catalyst to be regenerated subsequent to Fischer-Tropsch synthesis ill the presence thereof, the first wash fluid comprises a fluid in which at least a portion or a majority of the treatment or wash fluid is soluble.

[0056] in one or more embodiments of the present disclosure, the temperature of each wash (in the case of multiple wash steps) or the temperature of the wash (if mere is a single wash) is selected such that at least a portion of the wash fluid remains a liquid, hi one or more embodiments of the present disclosure, the temperature of each wash (in the case of multiple wash steps) or the temperature of the wash (if there is a single wash) is selected such that a majority of the was fluid remains a liquid. The specific iirst wash conditions will depend on the first wash fluid utilized. In one or more embodiments of the present disclosure, a first wash is carried out at a temperature in the range of from about 80°C to 180°C, in the range of from about 90°C to 140°C, or from about 100°C to 130°C. In one or more embodiments of the present disclosure, a first wash is carried out at a pressure of less than about 350 psig, less than about 125 psig, or less than about 100 psig.

[0057] The amount of the first wash fluid to be utilized can be easily determined by those of skill in the ait, and will depend on the nature of the FT catalyst, being regenerated. An FT catalyst with a smaller average pore size will generally require less first wash fluid per unit mass of catalyst than an FT catalyst having a larger average particle size. In one or more embodiments of the present disclosure, a first wash is carried out at a flow rate of the first wash fluid in the range of from about 5 gallons per ft ³ of FT catalyst to about 100 gallons per ft ^" ' of FT catalyst from about 10 gallons per ft of FT catalyst to about 20 gallons per fF ^' of FT catalyst, or from about 11 gallons per ft ³ of FT catalyst to about 15 gallons per ft ³ of FT catalyst,

jOOSSf As noted above, the first wash fluid is a suitable solvent for at least a portion of the material trapped in the pores and on the surface of the unwashed FT catalyst to be regenerated. The first wash fluid may comprise a Fischer-Tropsch cut. For example, as mentioned above, a straight ran FT hydrocarbon obtained by condensing the vapors coming from a Fischer-Tropsch synthesis reactor at a lower temperature than the FT synthesis temperature may be utilized ^' as first wash fluid. Such an FT hydrocarbon exits the Fischer- Tropsch synthesis reactor as vapor, typically in the presence of unreacted syngas. The straight nm FT liydrocaibon cut is liquid without the presence of additional gas at a reduced or first condensation temperature, wh ch may be, for example in the range of from about 100°C to about 180°C, as mentioned above. Thus, one or more embodiments of ^' the present disclosure, the first wash fluid comprises MFTL condensed from a vapor removed from a Fischer-Tropsch reactor during production of FT hydrocarbons at 11. Another suitable material for use as first wash fluid is diesel. In one or more embodiments of tiie present disclosure, the first wash fluid comprises FT produced fuels such as diesel. In one or more embodiments of the present disclosure, the first wash fluid comprises FT diesel. One or more embodiments of the present disclosure comprises producing at least a portion of the Fischer-Tropsch diesel via the Fischer-Tropsch conversion, for example at II. The FT diesel hydrocarbon fraction may be separated from the FT product hydrocarbons produced during FT synthesis at 11. in one or more embodiments of the present disclosure, the first wash fluid comprises primarily paraffins. Both a straight run MFTL cut and FT diesel are paraffmic in nature and are good solvents for a Fischer-Tropsch wax, which may be present in the pores of the FT catalyst to be regenerated.

[0059] Referring again to FiG. 1, in one or more embodiments of the present disclosure, the once-washed FT catalyst from 20 is further washed with one or more additional wash fluids at 3Θ. In one or more embodiments comprising a plurality of wash steps, the wash fluid from the previous wash may be removed (e.g. drained) prior to washing with the wash fluid of the subsequent wash. One or more embodiments of the present disclosure comprise washing with a second wash fluid. The second wash is preferably performed with a second wash fluid having a lower average molecular w ^r eight than the first wash fluid, hi one or more embodiments of the present disclosure, the second wash fluid comprises a straight run hydrocarbon, for example, an LFTL as described above, which may be collected (e.g. condensed from FT vapor) at a temperature in the range of from about 30°C to about 50°C. This LFTL hydrocarbon cut may be obtained through use of a three phase (i.e. water phase, vapor phase, arid hydrocarbon phase) separator, as known in the art. FT water would also likely be produced by the three-phase separator, as well as FT tail gas. Such an LFTL hydrocarbon fraction (without water) may be used for the second wash. In one or more embodiments of the present disclosure, the second wash fluid comprises naphtha. In one or more embodiments of the present disclosure, the second wash fluid comprises Fischer-Tropsch naphtha. One or more embodiments of the present disclosure comprise producing at least a portion of the Fischer-Tropsch naphtha via the Fischer-Tropsch conversion, for example at 11. The FT naphtha may be a hydrocarbon, fraction lighter than an FT diesel that is that is separated from the FT product hydrocarbo s produced during FT synthesis at 11.

[0060] The lighter hydrocarbon or hydrocarbon mixture of the second wash fluid is preferably a good solvent for the wash fluid utilized in the ^' first wash ^' (e.g. ^" for either the straight run MFTL hydrocarbon or the diesel). The amount of second wash fluid utilized in the second wash may be similar to or determined in the same manner as the amount of wash fl tid utilized in the first wash at 20.

[0061] The specific second wash conditions will depend on the second wash fluid utilized. In one or more embodiments of the present disclosure, a second wash carried out at 30 is performed ^' at a temperature in the range of from about 30°C to about S0°C, in the range o f om about 40°C to about 80°C, or in the range of from about 50°C to about 80 °C. hi one or more embodiments of the present disclosure, a second wash is carried out at a pressure of less than about 175 psig, less than, about 150 psig, or less than about 100 psig. in one or more embodiments of the present disclosure, a second wash carried out at 30 is performed at a flow rate of the second wash fluid in the range of from about 5 gallons per ft ³ of FT catalyst to about 100 gallons per fV of FT catalyst, from about 10 gallons per ft ³ of FT catalyst to about 20 gallons per ft ^J of FT catalyst, or from about 11 gallons per ft ^J of FT catalyst to about 1.5 gallons per ft ³ of FT catalyst.

[0062] As noted above, in one or more embodiments of the present disclosure, the second washing step is followed by a third (or more) wash(es) utilizing a wash fluid(s) having a lower average molecular weight than the material remaining in the pores of the FT catalyst after the second (previous) wash(es).

[0G63J Subjecting Washed FT Catalyst to Reduction and/or Oxidation at 40, One or more embodiments of the present disclosure further comprises subjecting washed FT catalyst to reduction and/or oxidation at 40. As indicated in F!G. J , subjecting the washed FT catalyst to reduction and/or oxidation at 40 may comprise subjecting the washed FT catalyst from step 20 and/or 30 to reduction and/or stripping at 41, subjecting the reduced FT catalyst from 41 to oxidation at 42, subjecting tlie oxidized FT catalyst from 42 to further reduction at 43, or a combination of two or more thereof.

p064] Following the final wash, a bulk wash fluid is removed from (e.g. drained from) the wash vessel (e.g. the FT reactor). Desirably, at this point a majority of the fluid associated with the FT catalyst (e.g. on tl e surface and/or within tlie pores thereof) comprises the final wash fluid (e.g. naphtha or LFTL). Hydrogen or nitrogen stripping may be performed subsequent to the final wash. Hydrogen vaporizes/strips hydrocarbons from the washed FT catalyst and increases exposed FT catalyst metal. Due to the disclosed washing with lighter hydrocarbons, most of the hydrocarbons that remain in tlie washed FT catalyst are components of the last wash fluid. Such hydrocarbons have a low boiling point relative to the material replaced thereby during the wash(es) and are thus more readily removed from the FT ^" catalyst during subsequent regeneration steps, e.g. reduction and/or oxidation. In one or more embodiments of tlie present disclosure, subjecting the washed FT catalyst to reduction and/or oxidation at 40 comprises contacting the washed FT catalyst with hydrogen or a hydrogen-containing gas, hi one or more embodiments of the present disclosure, subjecting the washed FT catalyst to reduction and/or oxidation at 40 comprises heating the washed catalyst to a temperature of greater than about 250°C in the presence of hydrogen or a hydrogen-eontahiing gas. The amount of heavy hydrocarbons (e.g. FT wax) that remains in the pores and/or on the surface of the washed FT catalyst is small relative to the amount within the pores and on the surface of the unwashed FT catalyst and will more readily crack. For example, a C50 hydrocarbon may crack to produce two C24 hydrocarbons, leaving two undesirable cokes behind. As cracking of heavier hydrocarbons generally produces coke, a reduction in the amount of heavier hydrocarbons, such as C50, associated with the FT catalyst (i.e. on the surface and/or in the pores thereof) prior to treatment at 40 reduces the amount of undesirable coke produced during the regeneration at 40, Thus, the amount of carbon deposited on the FT catalyst surface following regeneration at 40 is reduced minimized relative to the amount of carbon deposited on the FT catalyst surface following conventional regeneration procedures that lack the disclosed washing step(s).

[00651 Referring again to FlG. 1, in one or more embodiments of the present disclosure, subjecting the washed FT catalyst to reduction and/or oxidation at 40 comprises contacting the washed FT catalyst with hydrogen, thus subjecting the washed FT catalyst to stripping and/or reduction at 41. Such stripping/reduction may he performed as known in the art, although generally less extreme conditions may be required for processes performed in accordance with one or more embodiments of the present disclosure than for conventional stripping/reduction operations. The specific operating conditions utilized during hydrogen contacting at 41 will depend on the FT catalyst being regenerated and the composition of the final wash fluid. Thus, subjecting the washed FT catalyst to reduction at 41 may comprise contacting the washed FT catalyst with a gas comprising hydrogen. Contacting the washed FT catalyst with a gas comprising hydrogen may comprise introducing the gas comprising hydrogen into a Fischer-Tropsch reactor containing the washed FT catalyst, (in other embodiments, contacting the washed FT catalyst with a gas comprising hydrogen may comprise introducing the gas comprising hydrogen into a regeneration vessel, other than an FT reactor, containing the washed FT catalyst.) The gas comprising hydrogen may be introduced into a Fischer-Tropsch reactor containing the washed FT catalyst at a GLV in the range of from about 10 to about 40 cm/s, from about 15 to about 30 cm/s, or from about 20 to about 25 cm/s. ^" In one or more embodiments of the present disclosure, the hydrogen contacting at 41 is carried out at a temperature in the range of from about 428°F (220°C) to about 700°F ( 71°C), from about 500°F (260°C) to about 650°F (343 °C), or from about 536°F (280°C) to about 600°F (316°C). in one or more embodiments of the present di sclosure, the stripping and/or reduction at 41 is carried out at a pressure in the range of from about 50 psig to about 400 psig, from about 60 psig to about 300 psig, or from about 80 psig to about 130 psig. in one or more embodiments of the present disclosm e, the gas comprising hydrogen utilized at 41 comprises more than 60 volume percent hydrogen, more than 80 volume percent hydrogen, or more than 90 volume percent hydrogen.

|Θ066] The stripping and/or reduction with hydrogen at 41 may be performed for a duration of from about 4 hours to about 24 hours, and/or may utilize a number of heating and/or cooling steps as known in the art, though conditions for the stripping and/or reduction with hydrogen at 41 may be less severe than in conventional methods. The hydrocarbons leaving the reactor may be monitored to determine an optimal time to terminate the stripping reduction step at 41. For example, the hydrocarbons leaving the regeneration vessel (e.g. the FT reactor) may be relatively heavy at first, decreasing during the treatment For example, when the final wash fluid is naphtha, the step of stripping and/or reduction with hydrogen may be complete when the hydrocarbon product leaving the regeneration vessel comprises a composition similar to the naphtha.

50067] In. one or more embodiments of the present disclosure, the reduction at 41 provides a sufficiently activated FT catalyst, and no further treatment is necessary to provide rejuvenated FT catalyst suitable for FT synthesis. In other embodiments, further oxidation at 42 and or reduction at 43 are utilized to provide a more completely regenerated (i.e. activated) FT catalyst. In one or more embodiments of the present disclosure, subjecting the washed FT catalyst to reduction and/or oxidation at 40 further comprises subjecting the reduced FT catalyst from 41 to oxidation at 42. Such oxidation 42 may be performed as known in the art, although less extreme conditions may be required for oxidation for embodiments of the present disclosure than for conventional oxidation processes. Oxidation ma be utilized to burn off carbon deposits remaining after reduction. Because oxidation may be damaging to an FT catalyst, the disclosed regeneration method which comprises one or more FT catalyst wash with lighter materials may reduce the amount of damage to the FT catalyst during regeneration. A reduction in such damage may be enabled by a reduction in the severity (temperature, duration, etc.) of the oxidation required, or an elimination of the need for oxidation step 42. As known in the art, some FT catalysts are typically oxidized, while others may not ^' be oxidized. The question may be an economic one. Reduction or elimination of an oxidation step provided via embodiments of the disclosed method may serve to make the overall regeneration process more economical and or less time consuming. Generally, FT catalysts having smaller pores may require an oxidation step at 42, such "smaller" pore size known to those of ordinar skill in the art and depending on the specific FT catalyst being regenerated.

[0068] Subjecting the reduced FT catalyst from 41 to oxidation at 42 may comprise contacting the stripped and/or reduced FT catalyst with a gas comprising oxygen. In one or more embodiments of the present disclosure, subjecting the washed FT catalyst to oxidation at 42 comprises introducing a gas comprising oxygen into a Fischer-Tropsch reactor containing the stripped/reduced FT catalyst. Purging of the Fischer-Tropsch reactor with an inert gas may be performed prior to introduction of an oxygen-containing oxidizing gas thereto. For example, the Fischer-Tropsch. reactor may be purged with nitrogen and/or carbon dioxide prior to oxidation at 42. Thus, in one or more embodiments of the present disclosure, one or more embodiments of the present disclosure further comprise purging the treatment or regeneration vessel (e.g. the Fischer-Tropsch reactor) with an inert gas prior to oxidation at 42.

[0069] The specific oxidation conditions utilized during oxidation 42 will depend on the FT catalyst being regenerated and the condition of the FT catalyst after it has been subjected to the reduction/stripping step. The oxidation 42 may be carried out, for example, at a GLV in the range of from about 8 cm s to about 40 cm/s, from about 10 em/s to about 30 em s, or from about 15 crn/s to about 35 cm/s. The oxidation 42 may be carried out at a temperature in the range of from about 200°F (93°C) to about 650°F (343°C), from about 320°F (160°C) to about 626°F (330°C), or from about 356°F (180°C) to about 615°F (323°C). The oxidation 42 may be carried out at a pressure in the range of from about 50 psig to about 250 psig, from about 50 psig to about 140 psig, or from about 40 psig to about 120 psig. The gas comprising oxygen (i.e. the Oxidation" or ' oxidizing' gas) may comprise less than about 5 volume percent oxygen, less than about 4 volume percent oxygen, or less than about 3 volume percent oxygen. The gas comprising oxygen may comprise from about 0, 1 volume percent oxygen to about 5 volume percent oxygen, from about 0,2 volume percent oxygen to about 4 volume percent oxygen, or from about 0.2 volume percent oxygen to about 3 volume percent oxygen during the bulk of the oxidation process.

{0070} During oxidation 42, the amount of carbon dioxide exiting the regeneration vessel may be monitored. Oxidation 42 may be stopped when the increase of carbon dioxide exiling the vessel falls to zero (or when the amount of carbon dioxide exiting the vessel can no longer be distinguished from the reactor inlet, i.e. when the signal to noise ratio approaches or re-aches 1).

[0071 J In one or more embodiments of the present disclosure, the FT catalyst being regenerated is a cobalt-based catalyst and oxidation produces cobalt oxides, In one or more embodiments of the present disclosure, the FT catalyst being regenerated is an iron-based catalyst, and oxidation produces iron oxides.

[00721 in one or more embodiments of the present disclosure, subjecting the washed FT catalyst to reduction and/or oxidation at 40 further comprises subjecting the oxidized FT catalyst from 42 to an additional (e.g. a second reduction) reduction at 43, Such a reduction following oxidation may be performed as known in the art, although less extreme conditions may be required for reduction 43 than for conventional reductions. The specific reduction conditions utilized during the reduction at 43 will depend on the FT catalyst being regenerated. Subjecting the oxidized FT catalyst to a reduction at 43 may comprise contacting the oxidized FT catalyst with a reduction gas (e.g. a 'second' reduction gas when a reduction gas is also utilized at 41) comprising hydrogen. Subjecting the oxidized catalyst to the (e.g. second) reduction at 43 may comprise introducing a (second) reduction gas comprising hydrogen (which may be the same or different, from a gas utilized at 41) into the treatment or regeneration vessel (e.g. the Fischer-Tropsch reactor). The (e.g. second) reducing gas may be introduced into the treatment or regeneration vessel containing the oxidized FT catalyst at a GLV in the range of from about 10 to about 30 era's, f om about 10 to about 28 cm/s, or from about 13 to about 30 cra/s. Subjecting the oxidized FT catalyst to the reduction at 43 may be carried out at a reduction temperature (which may be the same or different from a reduction temperature utilized at 41) in the range of from about 400°F (204°C) to about 700°F (371°C), from about 450°F (232°C) to about 700°F (371 ^C C), or from about 450°F (232°C) to about 650°F (343°C). Subjecting the oxidized FT catalyst to reduction at 43 may be carried out at a reduction pressure in the range of from about 80 psig to about 400 psig, from about 80 psig to about 350 psig, or from about 90 psig to about 150 psig. The gas comprising hydrogen utilized at 43 (e.g. a second reduction gas) may comprise high purity hydrogen such as 4.5 grade hydrogen. In one or more embodiments of the present disclosure, the reduction gas utilized at 43 has a greater purity of hydrogen than the reduction gas utilized during reduction at 41. In one or more embodiments of the present disclosure, the reduction gas utilized at 43 comprises at least 20 volume percent hydrogen, at least 25 volume percent hydrogen, or at least 30 volume percent hydrogen. Although sometimes referred to herein as a 'second' reduction with a 'second' reducing gas, it is to be understood that reduction at 43 may be, in one or more embodiments, a first or only reduction step of the present disclosure.

[0073] in one or more embodiments of the present disclosure, the redaction at 43 provides a sufficiently activated FT catalyst, and no further treatment is necessary to provide regenerated, activated FT catalyst suitable for subsequent FT synthesis.

|0074| Following regeneration, the regenerated FT catalyst may be utilized to produce additional FT hydrocarbons. For example, when regenerated in situ, the Fischer-Tropsch reactor in which the FT catalyst was regenerated may be cooled to FT synthesis conditions (e.g. generally from about 1 0°C to about 230°C for operations using a cobalt-based FT catalyst) and FT synthesis initiated. As noted hereinabove, MFTL, LFTL, FT naphtha and or FT diesel produced during FT synthesis in the presence of the FT catalyst regenerated as described herein may be utilized as wash fluid during subsequent catalyst regeneration described hereinabove.

[0675] Apparatus for Regenerating FT Catalyst Also disclosed herein are a system and an apparatus for regenerating an FT catalyst. As mentioned hereinabove, the FT catalyst regeneration may be performed in siiu within a Fischer-Tropsch reactoi; or ex situ, in a distinct regeneration vessel or vessels. In one or more embodiments of the present disclosure, FT catalyst regeneration is performed in a Fischer-Tropsch reactor. Description of such an in siiu catalyst regeneration system will now be made with reference to I¾G. 3, which is a schematic of a Fischer-Tropsch catalyst regeneration system according to one or more embodiments of the present disclosure. The FT catalyst regeneration system depicted in FiG. 3 comprises a Fischer-Tropsch reactor 100 and may further comprise a first condensation apparatus 200, a second condensation apparatus 300, and or a downstream FT product separation and/or upgrading equipment 40Θ. (in other embodiments, a catalyst regeneration vessel(s) which is (are) not an FT reactor may be used instead of the Fischer-Tropsch reactor 100, though the system would be slightly modified as known to those of skill in the art.) Referring again to FfC. 3, the Fischer-Tropsch reactor 100 may be any Fischer-Tropsch reactor known in the art to be suitable for FT synthesis. In one or more embodiments of the present disclosure, the Fischer-Tropsch reactor ίθθ is a fixed bed Fischer-Tropsch reactor. An inlet line 110 is configured to introduce a synthesis gas feed into the Fischer-Tropsch reactor 100 during FT synthesis. A liquid outlet 120 may be configured for removal of FT product liquid hydrocarbons from the Fischer-Tropsch reactor 100. A vapor outlet line 130 may be configured for extraction of a vapor from the Fischer-Tropsch reactor 100. In alternative embodiments, a single fluid outlet may be utilized to remove fluids from the Fi cher-Tropsch reactor 100, and a vapor/liquid separator may be utilized to separate a vapor from product liquid hydrocarbons (and optionally from FT catalyst in embodiments in which the Fischer- Tropsch reactor 190 is a slurry bubble column reactor or 'SBCR').

[0076! During operation, a synthesis gas feed is introduced into the Fischer-Tropsch reactor 100 via the syngas inlet line 110, Liquid product hydrocarbons may be removed from the Fischer-Tropsch reactor 100 via the liquid product outlet line 120, and vapor may be extracted from the Fischer-Tropsch reactor ίθθ via the vapor outlet line 130. Alternativel , as mentioned above, a fluid comprising FT vapor and liquid FT hydrocarbons may be removed via a single line and FT vapor may be separated from the FT liquids (and/or FT catalyst) in a V/L separator (not indicated in FIG, 3).

[0077] Continuing to refer to FIG. 3, a wash fluid inlet line 140 is configured for introduction of a wash fiuid(s) into the Fischer-Tropsch reactor 100 during FT catalyst regeneration. A liquid outlet line 150 is configured to drain bulk fluids from the Fischer-Tropsch reactor 100 following FT synthesis {i.e. to drain bulk product FT hydrocarbons) and/or during and/or subsequent to an FT catalyst wash,

10078} As noted hereinabove, an MFTL may be utilized as or as a component of a first wash, and/or an LFTL may be utilized as or as a component of a second wash, A catalyst regeneration system in accordance with the present invention may thus further comprise a first condenser 290 configured to condense MFTL from a vapor extracted from the Fischer- Tropsch synthesis reactor 100 during the FT synthesis and introduced into the first condensation apparatus 200, which may comprise a first condenser, via the vapor outlet line 130. The MFTL exits the first condensation apparatus 200 via an MFTL outlet line 220. The second condensation apparatus 300, which may comprise a second condenser, may be configured to condense LFTL from a vapor exiting the first condensation apparatus 2Θ0 via a line 210. Uncondensed vapor exits the second condensation apparatus 300 via an uncondensed vapor line 310, while the LFTL extracted from the second condensation apparatus 300 exits via an LFTL outlet line 320, The FT water streams are not depicted in FIG. 3.

[0«79j The MFTL outlet line 220 may be configured to introduce at least a portion of the MFTL into the Fischer-Tropsch reactor 100, for example via the wash fluid inlet line 140, whereby at least a portion of the MFTL condensed via the first condensation apparatus 200 may be utilized as a wash fluid {e.g. as a first wash fluid), in one or more embodiments of the present disclosure. [09S0] The LFTL outlet line 320 may he configured to introduce at least a portion of the MFTL into the Fischer-Tropsch reactor 100. for example via the wash fluid inlet line 140, whereby at least a portion of the LFTL condensed via the second condensation apparatus 300 may be utilized as a wash fluid (e.g. as a second wash fluid), in one or more embodiments of the present disclosure.

post] Referring again to FiG. 3, the downstream FT product separation and/or upgrading equipment 400 may he configured for separation and/or upgrading of one or more of the collected FT liquids produced in the Fischer-Tropsch reactor 100. The MFTL outlet line 220, the LFTL outlet line 320, the liquid product outlet line J 20, and the liquid outlet line ISO flow to the downstream FT product separation and/or upgrading equipment 00 via a mixed fiowlme 121. The downstream FT product separation and or upgrading equipment 400 may he configured to provide an FT naphtha, which may he removed therefrom vi an FT naphtha outlet line 420. The downstream FT product separation and or upgrading equipment 400 may he configured to provide an FT diesel, which may he removed therefrom via an FT diesel outlet line 430. The FT naphtha outlet line 420, the FT diesel outlet line 430, or both, may be fluidly connected with the Fischer-Tropsch reactor 100, for example via the wash fluid inlet line 140, whereby at least a portion of the FT naphtha may be utilized as a wash fluid (e.g. as a second wash fluid), at least a portion of the FT diesel may be utilized as a wash fluid (e.g. as a first wash fluid), or both. Suitable downstream FT product separation and/or upgrading equipment 400 are well known to those of skill in the art.

[00821 While some preferred embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations. The use of the term "optionally" with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, and the like.

[0083] Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims that follow, that scope including all equivalents of the subject matter of the claims, Each and every claim is incorporated into the specification as an embodiment of the present invention. Thus, the claims are a further description and are an addition to the preferred embodiments of the present invention. The inclusion or discussion of a reference is not an admission that it is prior art to the present invention, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent they provide background knowledge; or exemplary, procedural or oilier details supplementary to those set forth herein..