Method for producing a Fischer-Tropsch synthesis catalyst and a Fischer-Tropsch initiation process

Abstract

The present invention relates to a method for preparing a Fischer-Tropsch synthesis catalyst in which 15 to 40 mole percent of the cobalt is in the form of cobalt oxide. The present invention also relates to a start-up process for a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, wherein 15 to 40 mole percent of the cobalt is in the form of cobalt oxide, and the reduced and passivated catalyst is activated by contacting the catalyst with a synthesis gas stream.

Description

[Technical Field]

[0001] The present invention relates to a method for preparing a Fischer-Tropsch synthesis catalyst. In particular, the present invention relates to a method for preparing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, in which 15 to 40 mole percent of the cobalt is in the form of cobalt oxide. The present invention also relates to a start-up process for a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, in which 15 to 40 mole percent of the cobalt on the catalyst is in the form of cobalt oxide. [Background technology]

[0002] The conversion of synthesis gas to hydrocarbons by the Fischer-Tropsch process has been known for many years. The growing importance of alternative energy sources has led to renewed interest in the Fischer-Tropsch process as one of the more attractive, direct, and environmentally acceptable routes to high-quality transportation fuels.

[0003] For example, many metals such as cobalt, nickel, iron, molybdenum, tungsten, thorium, ruthenium, rhenium and platinum are known to be catalytically active, either alone or in combination, in the conversion of synthesis gases to hydrocarbons and their oxygenated derivatives.

[0004] In the preparation of Fischer-Tropsch synthesis catalysts, a cobalt-containing compound, which can be, for example, an organometallic or inorganic compound, is generally converted to form cobalt oxide (e.g., CoO, Co2O3, or Co3O4), followed by a calcination / oxidation step. Following the generation of cobalt oxide, a reduction step is required to form pure cobalt metal as the active catalytic species. Therefore, the reduction step is also commonly referred to as the activation step.

[0005] Activation of Fischer-Tropsch catalysts in commercial plants is expensive and time-consuming. Typically, catalysts are activated by reducing the metals under hydrogen at temperatures exceeding 300 °C. Because the reduced and activated catalyst is sensitive to oxidation in air, activation with hydrogen is generally performed in situ on the oxidized catalyst before performing Fischer-Tropsch synthesis. Catalysts can be passivated to reduce their reactivity by reducing the metals and subsequently oxidizing the catalyst for transportation and storage. The passivated catalyst can then be activated in situ under hydrogen before performing Fischer-Tropsch synthesis.

[0006] Additional equipment and capital expenditures are required to provide high-temperature hydrogen reduction treatment for in-situ catalyst activation in commercial plants. Catalyst activation can generally be performed on new catalysts every 1 to 5 years using hydrogen reduction equipment, which is not required during intervening Fischer-Tropsch process operations. Reduction of oxidation catalysts with hydrogen also produces water, which can damage catalyst activity downstream of where water is produced in the catalyst bed. For this reason, compressors are used to provide high flow rates to more quickly remove water during production.

[0007] There remains a need for Fischer-Tropsch catalysts and processes that can avoid the frequently used and expensive equipment and conditions associated with Fischer-Tropsch catalyst activation. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Brunauer, S, Emmett, PH, & Teller, E, J. Amer, Chem. Soc.60, 309, (1938) [Non-patent document 2] Barrett, EP, Joyner, LG & Halenda P, J. Am Chem. Soc., 1951 73 373-380 Summary of the Invention [Problem to be solved by the invention]

[0009] It has now surprisingly been found that by reducing a cobalt-containing Fischer-Tropsch catalyst and performing a controlled partial oxidation of the catalyst to give a reduced and passivated catalyst in which 15-40 mol% of the cobalt on the catalyst is in the form of cobalt oxide, the catalyst can be advantageously activated using synthesis gas rather than hydrogen, and under milder conditions than typically used. [Means for solving the problem]

[0010] Accordingly, an aspect of the present invention provides a method for producing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, the method comprising the steps of: (a) contacting a cobalt-containing Fischer-Tropsch catalyst with a reducing gas under conditions suitable to form a reduced cobalt-containing Fischer-Tropsch catalyst; (b) adjusting the temperature of the reduced cobalt-containing Fischer-Tropsch catalyst to a temperature in the range of 0°C to 200°C under a non-oxidizing atmosphere; (c) contacting the reduced cobalt-containing Fischer-Tropsch catalyst with an oxygen-containing gas stream comprising 0.1% v / v to 5% v / v oxygen, the balance being an inert gas, at a temperature in the range of 0°C to 200°C to produce a reduced and passivated cobalt-containing Fischer-Tropsch catalyst; wherein in step (c), the amount of oxygen in the oxygen-containing gas stream and the temperature are selected and maintained to produce a reduced and passivated cobalt-containing Fischer-Tropsch catalyst having 15 to 40 mole % of the cobalt thereon in the form of cobalt oxide.

[0011] By controlling the temperature and oxygen content of the gas stream used to passivate the catalyst to produce a reduced and passivated cobalt-containing Fischer-Tropsch catalyst in which 15-40 mole % of the cobalt is in the form of cobalt oxide, one can produce a catalyst that can be advantageously activated under syngas conditions in a Fischer-Tropsch reactor and / or under relatively mild conditions while retaining catalytic activity.

[0012] Without wishing to be bound by any particular theory, it is believed that controlling the temperature and oxygen content of the oxidizing gas stream to limit the cobalt oxide content to 15-40 mole percent provides mild passivation of the catalyst, oxidizing the surface of the catalyst to protect it from oxidation during shipping and storage, while reducing or avoiding oxidation of the bulk catalyst below the surface. Avoiding such oxidation of the bulk catalyst below the surface is believed to avoid the typical requirement for reducing the catalyst under hydrogen at high temperatures.

[0013] In step (a) of the process, the cobalt-containing Fischer-Tropsch catalyst is reduced. The reduction can be carried out by any known means known to those skilled in the art to convert cobalt oxide to catalytically active cobalt metal. The reduction step can be carried out batchwise or continuously in a fixed-bed, fluidized-bed, or slurry-phase reactor. The reduction step can include contacting the cobalt-containing Fischer-Tropsch catalyst with a hydrogen stream, e.g., a gas stream consisting essentially of hydrogen. In another example, the reduction step can be carried out using a hydrogen stream containing hydrogen in combination with an inert gas or consisting essentially of hydrogen. Suitably, the hydrogen stream can contain at least 80% v / v hydrogen, preferably at least 90% v / v hydrogen, e.g., at least 95% v / v or at least 99% v / v hydrogen. The reduction can be carried out at a temperature of 200°C to 600°C, preferably 300°C to 500°C. The reduced cobalt-containing Fischer-Tropsch catalyst may preferably be reduced in step (a) such that no more than 10 mol% of the cobalt on the catalyst is in the form of cobalt oxide, preferably no more than 5 mol% of the cobalt on the catalyst is in the form of cobalt oxide.

[0014] Step (b) of the present method involves adjusting the temperature of the reduced cobalt-containing Fischer-Tropsch catalyst to a temperature in the range of 0°C to 200°C under a non-oxidizing atmosphere. Step (b) can last any suitable length of time, which can be determined based on the time required to adjust the temperature of the catalyst to the desired value or range, e.g., the time required to cool the catalyst from the temperature used to carry out the reduction of the catalyst in step (a). In some cases, once the temperature of the catalyst has reached the desired value or range, step (c) can be carried out. In other examples, the catalyst can be stabilized at the desired temperature value or range for a period of time before step (c) is carried out.

[0015] The non-oxidizing atmosphere can comprise any suitable gas or mixture of gases. In some cases, the non-oxidizing atmosphere can be an atmosphere containing at least a portion of the reducing gas used in step (a), e.g., the reducing atmosphere from part (a) can be maintained in step (b). In some cases, the non-oxidizing atmosphere can be an inert atmosphere, e.g., an atmosphere consisting essentially of nitrogen and / or other inert gases, such as argon, or a mixture of one or more inert gases with one or more reducing gases, such as hydrogen. Preferably, the catalyst and reactor are purged with an inert gas before or during step (b), e.g., to remove residual hydrogen from the reactor.

[0016] In step (c), the reduced cobalt-containing catalyst is contacted with an oxygen-containing gas stream. The oxygen-containing gas stream contains 0.1% v / v to 5% v / v oxygen, the remainder being an inert gas. The inert gas can be any inert gas or gas mixture, for example, the inert gas can be nitrogen or argon, and preferably the inert gas is nitrogen.

[0017] Preferably, the oxygen-containing gas stream comprises 0.2% v / v to 2.5% v / v oxygen, for example, 0.3% v / v to 2% v / v oxygen or 0.5% v / v to 2% v / v oxygen. In some preferred embodiments, the oxygen-containing gas stream comprises 1% v / v or less oxygen, for example, less than 1% v / v oxygen, or the oxygen-containing gas stream comprises 0.5% v / v or less oxygen, for example, less than 0.5% v / v oxygen.

[0018] The reduced cobalt-containing Fischer-Tropsch catalyst is contacted with the oxygen-containing gas stream in step (c) at a temperature in the range of from 0° C. to 200° C. Preferably, the reduced cobalt-containing Fischer-Tropsch catalyst is contacted with the oxygen-containing stream at a temperature in the range of from 5° C. to 150° C., preferably from 10° C. to 100° C., more preferably from 20° C. to 80° C., for example from 30° C. to 60° C.

[0019] The catalyst may be heated by any suitable means, for example, the catalyst may be heated by an external heater arranged to apply heat to the catalyst, or may be itself heated, for example, by one or more electric heating elements or heat exchangers arranged to heat the catalyst by and / or in response to a flow of gas over the catalyst.

[0020] The temperature selected and maintained in step (c) may be the temperature at which the catalyst was prepared in step (b). It is understood that the temperature increase may result from an exothermic reaction that oxidizes the reduced cobalt of the reduced cobalt-containing catalyst. Therefore, the temperature of the catalyst is preferably maintained within the temperate range, e.g., within the temperature range discussed above. For example, in step (c), the temperature of the catalyst may be increased during step (c), but is prevented from exceeding 200°C. Preferably, the temperature of the catalyst is prevented from exceeding 150°C, more preferably 100°C, and most preferably 80°C, e.g., 60°C.

[0021] To control the temperature of the catalyst, the catalyst temperature may be reduced, the temperature increase may be slowed, or it may be stopped to maintain a constant temperature. The temperature of the catalyst may be prevented from exceeding a certain temperature by any suitable means. For example, the heat applied to the catalyst by a heater may be stopped or reduced, or the oxygen content of the oxygen-containing stream may be reduced. In some instances, the oxygen-containing stream may be diluted or replaced with an inert gas stream to prevent the temperature from increasing. In some instances, the catalyst may be actively cooled, for example, using one or more heat exchangers positioned to extract heat from the catalyst or by actively reducing the temperature of the oxygen-containing gas stream. In some cases, the flow rate of the oxygen-containing gas stream over the catalyst may be increased to increase heat transfer away from the catalyst by the gas.

[0022] Without wishing to be bound by any particular theory, it is believed that if the temperature of the catalyst is not controlled, for example, by selecting the applied temperature and / or the oxygen content of the oxygen-containing gas stream, the heat generated during the passivation process can cause significant bulk oxidation of the cobalt on the catalyst in addition to surface oxidation. This can cause an increase in the overall cobalt oxide content of the catalyst and the need for high-temperature reduction under hydrogen to activate the catalyst.

[0023] The amount of oxygen in the oxygen-containing gas stream and the temperature in step (c) are selected to produce a reduced and passivated cobalt-containing Fischer-Tropsch catalyst in which 15 to 40 mole percent of the cobalt thereon is in the form of cobalt oxide. Surprisingly, it has been discovered that if the oxidation during the passivation step is controlled to yield a reduced and passivated cobalt-containing Fischer-Tropsch catalyst in which 15 to 40 mole percent of the cobalt is in the form of cobalt oxide, the catalyst can be activated under relatively mild conditions and / or under a syngas stream rather than a hydrogen stream. This may allow the expense of a hydrogen reduction unit to be avoided in commercial Fischer-Tropsch plants. The low level of oxidation may also avoid the need for a compressor to provide high flow over the catalyst during reduction to remove water and prevent catalyst deactivation at the end of the catalyst bed.

[0024] In a preferred embodiment, 20 to 38 mol% of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide. Preferably, no more than 35 mol% of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide, e.g., no more than 33 mol% or no more than 30 mol%.

[0025] It is understood that the temperature and oxygen content can be varied within the ranges previously defined to achieve the cobalt oxide content of the catalyst.

[0026] The cobalt oxide content of the reduced and passivated cobalt-containing Fischer-Tropsch catalyst may be determined by any suitable means, and such methods are known in the art.

[0027] For example, the cobalt oxide content of a reduced and passivated catalyst can be measured by temperature-programmed reduction (hereafter referred to as TPR), a method well known in the art. For example, a sample of catalyst may be heated in a fixed-bed tubular reactor from a low temperature (e.g., ambient temperature) in a stepwise manner under a flow of a reducing gas, such as hydrogen, at increasing temperatures. The reducing gas may be diluted in an inert gas, such as 1% v / v to 20% v / v hydrogen in nitrogen, or 1% v / v to 10% v / v hydrogen in nitrogen. The temperature range may include from about ambient temperature, e.g., about 25°C, to a maximum temperature at which no further reduction of the catalyst is observed, e.g., about 550°C or even around 600°C. The amount of hydrogen consumed by the catalyst during reduction across the temperature profile is measured to indicate the amount of cobalt oxide present on the catalyst. This can be compared to the known total cobalt content of the catalyst in question to determine the proportion of cobalt on the catalyst in the form of cobalt oxide. The amount of hydrogen consumed may be measured directly, for example, by comparing the hydrogen concentration after the catalyst with the hydrogen concentration in the gas fed to the catalyst, or the amount of hydrogen consumed may be measured indirectly, for example, by measuring the amount of water produced from the reduction of cobalt oxide on the catalyst by hydrogen. Any suitable measurement device can be used to measure hydrogen consumption, including, for example, mass spectrometry or thermal conductivity detection.

[0028] For example, TPR analysis may be performed using an analyzer such as a Micromeritics 2920 AutoChem II analyzer coupled with an integrated thermal conductivity detector (TCD) and a Cirrius 2 quadrupole mass spectrometer. Approximately 50 mg of catalyst sample can be loaded into a sample tube, such as a quartz glass U-tube, and dried under a flow of inert gas such as nitrogen or argon. The sample can then be heated from room temperature to 110°C at 5°C / min and held for 15 minutes. The sample can then be cooled to room temperature under an inert atmosphere. TPR analysis can be performed, for example, using 4% v / v hydrogen in argon (30 ml / min) and heating from room temperature to 550°C at a rate of 5°C / min.

[0029] The amount of reduction can be measured as a function of temperature during the TPR test. Bulk oxidation of the catalyst can also be indicated by the presence of a broad peak in the TPR test for reduction occurring above 200°C. For example, a broad peak in the range of about 200°C to 300°C can indicate the reduction of bulk CoO to CoO, while a broad peak in the range of about 300°C to 500°C can indicate the reduction of bulk CoO to Co metal. In contrast, reduction of surface cobalt oxide can be observed as one or more relatively narrow peaks in the range of about 150°C to 200°C. Preferably, in the TPR test, the reduced and passivated cobalt-containing catalyst does not exhibit catalyst reduction at temperatures above 250°C, more preferably 230°C, e.g., 200°C.

[0030] Surface oxidation of the catalyst can also be observed by X-ray diffraction. For over-oxidized catalysts, peaks corresponding to cobalt oxide can be observed, indicating bulk oxidation of the cobalt in the catalyst. When surface-passivated catalysts are prepared, the cobalt oxide peaks in the X-ray diffraction spectrum will be absent, since only the bulk cobalt metal below the surface can be observed, not the cobalt oxide layer on the surface.

[0031] In a preferred embodiment, the amount of oxygen in the oxygen-containing gas stream and the temperature are selected by the steps of: (i) carrying out steps (a)-(c) of a method for producing a Fischer-Tropsch catalyst having a predetermined composition at a first temperature under a predetermined set of process conditions using an oxygen-containing gas stream having a first oxygen content to produce a test catalyst; (ii) determining the percentage of cobalt on the test catalyst that is in the form of cobalt oxide by performing a temperature programmed reduction of the test catalyst; (iii) If the proportion of cobalt on the test catalyst that is in the form of cobalt oxide is outside the range of 15 to 40 mole percent, repeat steps (i) and (ii) at a second temperature and / or a second oxygen content different from the first temperature and / or a second oxygen content different from the first oxygen content.

[0032] Preferably, a reduced and passivated catalyst may be prepared in step (i), and a test catalyst sample from the reduced and passivated catalyst may be analyzed in step (ii). It is understood that a range of 15 to 40 mol% in step (iii) may be suitable, which may be the preferred range as described herein above.

[0033] Temperature programmed reduction as described in step (ii) is well known in the art and can be carried out as described earlier herein. Alternatively, the proportion of cobalt on the test catalyst in the form of cobalt oxide can be determined by any other suitable method known to those skilled in the art.

[0034] If the cobalt oxide content of the catalyst produced in step (i) is higher than the desired range of cobalt oxide contents, steps (i) and (ii) can be repeated using a temperature lower than the first temperature and / or an oxygen content of the oxygen-containing gas stream lower than the first oxygen content. Similarly, if the cobalt oxide content of the catalyst produced in step (i) is lower than the desired range of cobalt oxide contents, steps (i) and (ii) can be repeated using a temperature higher than the first temperature and / or an oxygen content of the oxygen-containing gas stream higher than the first oxygen content.

[0035] The catalyst used in repeating steps (i) and (ii) may be the same catalyst that was tested in step (ii) in the first instance, in which case the catalyst is then re-reduced and re-passivated under different conditions. Alternatively, the catalyst used in repeating steps (i) and (ii) may be a different but equivalent catalyst sample, for example, a catalyst made by the same method or from the same catalyst batch, or a mixture thereof.

[0036] Although the temperature and oxygen content of the oxygen-containing gas stream are mentioned, it is understood that for a given temperature and oxygen content, other conditions may also affect the oxidation level of the catalyst. Thus, conditions other than the temperature and oxygen content of the oxygen-containing gas stream may be constant between steps (i) and (iii). For example, the pressure of the oxygen-containing gas stream and / or the GHSV of the oxygen-containing gas stream over the catalyst may be constant between steps (i) and (iii). Alternatively, the pressure and / or the GHSV may be increased or decreased, respectively, in addition to the temperature and / or the oxygen content of the oxygen-containing gas stream to control the level of oxidation.

[0037] Any suitable reactor can be used in this process, and preferably, steps (a)-(c) are carried out continuously in the same reactor by adjusting the flow of different gases into the reactor. For example, the process can be carried out in a fixed-bed, fluidized-bed, or slurry-phase reactor. Preferably, in steps (a)-(c), the reducing gas, the oxygen-containing stream, and / or the non-oxidizing atmosphere are contacted continuously with the cobalt-containing Fischer-Tropsch catalyst in a fixed-bed reactor.

[0038] Preferably, the oxygen-containing stream is heated for 1000 to 30000 h -1 , preferably 5000 to 10000h -1 Preferably, the GHSV of the oxygen-containing gas stream over the catalyst is 1000 h -1 (e.g. at least 2000h -1When the GHSV of the oxygen-containing gas stream over the catalyst is at a higher level during step (c), the flow rate may have a cooling effect on the catalyst, resulting in reduced heat generation and reduced potential for over-oxidation.

[0039] Preferably, the contacting step is carried out at a pressure of from 1 bar absolute to 31 bar absolute, preferably from 1 bar absolute to 6 bar absolute, and most preferably at about atmospheric pressure. Higher pressures may promote oxidation of the reduced catalyst, which may in some cases lead to increased heat generation and over-oxidation of the passivated catalyst.

[0040] Contacting step (c) can be carried out for any suitable length of time to allow for the desired oxidation of the catalyst. For example, contacting step (c) can be carried out for 5 minutes to 168 hours, 5 minutes to 120 hours, 5 minutes to 72 hours, 5 minutes to 48 hours, or preferably 5 minutes to 24 hours. Preferably, contacting step (c) is carried out for at least 15 minutes, preferably at least 30 minutes, e.g., at least 45 minutes, or at least 1 hour. In some preferred embodiments, contacting step (c) is carried out for 30 minutes to 4 hours, e.g., 30 minutes to 2 hours.

[0041] Once the reduced and passivated catalyst is prepared, the catalyst can be stable for storage, e.g., at least several weeks or months, without significant loss of activity, depending on storage conditions. Preferably, the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is stored under a dry atmosphere, more preferably under an inert atmosphere such as a nitrogen or argon atmosphere.

[0042] In some embodiments, the reduced and passivated cobalt-containing Fischer-Tropsch catalyst may be coated with a wax or hydrocarbon, which may enhance the stability of the catalyst.

[0043] The cobalt-containing catalyst for use in the method of the present invention may be a freshly prepared catalyst material. Alternatively, the cobalt-containing catalyst may be obtained from a cobalt-containing material previously used to catalyze a Fischer-Tropsch reaction. If necessary, the cobalt-containing material previously used to catalyze a Fischer-Tropsch reaction may be calcined and / or appropriately reduced prior to use in the method.

[0044] The cobalt-containing Fischer-Tropsch catalyst may be unsupported or preferably supported on a conventional refractory support material, for example, the reduced cobalt-containing Fischer-Tropsch catalyst is preferably supported on a support material selected from the list consisting of silica, alumina, silica / alumina, ceria, titania, gallia, zirconia, magnesia, zinc oxide, and mixtures thereof, preferably titania, zinc oxide, ceria, alumina, or zirconia, and mixtures thereof, more preferably titania.

[0045] The level of cobalt loading on the support material can be any suitable loading. Preferably, the cobalt loading on the support material can be 5 to 25 wt. % cobalt based on the weight of the reduced catalyst, and particularly the cobalt loading on the support material can be 10 to 15 wt. %.

[0046] Preferred support materials are substantially free of extraneous components that may adversely affect the catalytic activity of the system. Accordingly, preferred support materials are at least 95% pure by weight, more preferably at least 98% pure by weight, and most preferably at least 99% pure by weight. Support purity generally refers to the composition of the support material, with the understanding that different phases of the material may still be present. For example, a support may be pure in that it contains a certain percentage of material, such as titania or alumina, but may contain different phases of that material, such as titania or alpha, delta, gamma, anatase, and rutile phases. Impurities are preferably less than 1% by weight, more preferably less than 0.50% by weight, and most preferably less than 0.25% by weight. The pore volume of the support is preferably greater than 0.150 ml / g, more preferably greater than 0.25 ml / g, e.g., greater than 0.5 ml / g. The average diameter of the proppant (before infiltration) should be between 10 and 500 Å, preferably between 15 and 100 Å, more preferably between 20 and 80 Å, and most preferably between 25 and 40 Å. The BET surface area should be between 2 and 1000 m 2 / g is suitable, and preferably 10 to 600m 2 / g, more preferably 15 to 100 m / g, most preferably 30 to 60 m 2 / g.

[0047] BET surface area, pore volume, pore size distribution, and average pore diameter can be determined from nitrogen adsorption isotherms determined at 77 K using a Micromeritics TRISTAR 3000 static volumetric adsorption analyzer. Procedures that can be used are the application of British Standard Methods BS4359:Part 1:1984, "Recommendations for Gas Adsorption (BET) Method," and BS7591:Part 2:1992, "Porosity and Pore Size Distribution of Materials"—methods of evaluation by gas adsorption. The resulting data can be reduced using the BET method (over a pressure range of 0.05-0.20 P / Po) and the Barrett, Joyner & Halenda (BJH) method (for pore sizes 20-1000 Å) to yield surface area and pore size distribution, respectively.

[0048] Suitable references for the above data reduction methods are given in Non-Patent Document 1 and Non-Patent Document 2.

[0049] The supported cobalt-containing Fischer-Tropsch catalyst used in step (a) can be prepared by any suitable method recognized by those skilled in the art. For example, it can be prepared by impregnation, precipitation, or gelation. Suitable Fischer-Tropsch catalysts can also be prepared by kneading or milling a support material such as silica, alumina, silica / alumina, ceria, titania, gallia, zirconia, magnesia, or zinc oxide with either a soluble or insoluble cobalt compound, followed by extrusion, drying, and calcination of the product.

[0050] Suitable impregnation methods include, for example, impregnating the support material with a compound of cobalt that is thermally decomposable to the oxide form. Any suitable impregnation technique can be used, including incipient wetness or excess solution techniques known in the art. The incipient wetness technique is so-called because it requires predetermining the volume of the impregnation solution to provide the minimum volume of solution necessary to just wet the entire surface of the support, without excess liquid. The excess solution technique, as the name suggests, requires an excess of impregnation solution, and the solvent is then removed, usually by evaporation.

[0051] The impregnation solution can be either an aqueous or non-aqueous, organic solution of the thermally decomposable cobalt compound. Suitable non-aqueous organic solvents include, for example, alcohols, ketones, liquid paraffin hydrocarbons, and ethers. Alternatively, an aqueous organic solution of the thermally decomposable cobalt compound, such as an aqueous alcohol solution, can be used.

[0052] Suitable soluble compounds include, for example, cobalt nitrates, acetates or acetylacetonates, preferably the nitrates. It is preferable to avoid the use of cobalt halides, as these can be harmful to the catalyst.

[0053] Impregnation may be carried out with the support material in powder, granular or pelletized form, or impregnation may be carried out with the support material in the form of a shaped extrudate.

[0054] It will be appreciated that where a preformed support or extrudate is impregnated, the support may be contacted with the impregnation solution by any suitable means including, for example, vacuum impregnation, incipient wetness, or immersion in excess liquid.

[0055] When powders or granules of the carrier material are impregnated, the powders or granules may be mixed with the impregnation solution by any suitable means known to those skilled in the art, such as adding the powders or granules to a container of the impregnation solution and stirring. When the extrusion step immediately follows the impregnation of the powders or granules, the mixture of the powders or granules and the impregnation solution may be further processed if it is not in a form suitable for extrusion. For example, the mixture may be kneaded to reduce the presence of larger particles that may not be easily extruded or whose presence would otherwise impair the physical properties of the resulting extrudate. Mulling typically involves forming a paste suitable for shaping by extrusion. Any suitable mulching or kneading device known to those skilled in the art can be used for mulching in the context of the present invention. For example, a pestle and mortar may be suitable for some applications, or a Simpson muller may be suitable. Mulling typically occurs for a period of 3 to 90 minutes, preferably 5 to 30 minutes. Mulling can be suitably carried out over a range of temperatures, including ambient temperature. A preferred temperature range for mulching is 15°C to 50°C. Marbling may suitably be carried out at ambient pressure. It will be appreciated that complete removal of bound solvent from the impregnation solution may be carried out to effect complete precipitation after extrusion.

[0056] In embodiments in which the impregnated powder or granules are subjected to a calcination step to completely remove the impregnation liquid solvent, the calcined powder or granules may be further processed to form a mixture suitable for extrusion. For example, an extrudable paste may be formed by combining the calcined powder or granules with a suitable solvent, such as the solvent used for impregnation, preferably an aqueous solvent, and kneading as described above.

[0057] In some embodiments, the extrudate or preformed support is converted to a powder or granules. This can be accomplished by any suitable means known to those skilled in the art. For example, the impregnated support material, which in some embodiments may be a dried extrudate, may be crushed / milled and / or pulverized. In preferred embodiments, the powder formed has a median particle size (d50) of less than 50 μm, preferably less than 25 μm. If granules are formed instead, the median particle size (d50) of the granules is preferably 300-600 μm. The particle size (d50) may suitably be determined by a particle size analyzer (e.g., a Microtrac S3500 particle size analyzer).

[0058] Suitable precipitation methods for producing cobalt-containing catalysts include, for example, (1) precipitating cobalt with the formation of its insoluble, thermally decomposable compounds at a temperature ranging from 0°C to 100°C using a precipitating agent including ammonium hydroxide, ammonium carbonate, ammonium bicarbonate, tetraalkylammonium hydroxide, or an organic amine, and (2) recovering the precipitate obtained in step (1).

[0059] In contrast to the impregnation method, any soluble salt of cobalt can be used. Suitable salts include, for example, carboxylates, chlorides, and nitrates. It is preferable to use an aqueous solution of the cobalt salt, but if necessary, for example, an aqueous alcoholic solution can be used.

[0060] In addition to ammonium carbonate, ammonium bicarbonate, and ammonium hydroxide, tetraalkylammonium hydroxide and organic amines can also be used as precipitants. The alkyl group of the tetraalkylammonium hydroxide is preferably C1 to C4. A suitable organic amine is cyclohexylamine. Experiments have shown that the use of alkali metal precipitants can result in very poor catalysts. Therefore, it is preferable to avoid the presence of alkali metals in the catalyst composition. Alkali-metal-free compositions can be suitably prepared using either ammonium carbonate or ammonium bicarbonate, and even more preferably ammonium bicarbonate, as the precipitant. Ammonium carbonate can be suitably used in its commercially available form, including a mixture of ammonium bicarbonate and ammonium carbonate. Instead of using preformed carbonate or bicarbonate salts, it is possible to use precursors of these salts, such as soluble salts and carbon dioxide.

[0061] Regardless of the method for preparing the cobalt-containing material, the cobalt-containing material may be converted to a catalyst containing cobalt in oxide form for subsequent reduction according to the present method. Calcination may be used to obtain a catalyst containing cobalt in oxide form, for example, by causing thermal decomposition of a previously formed pyrolytic compound of cobalt. Calcination may be carried out by any method known to those skilled in the art, for example, in a fluidized bed or rotary kiln, at a suitable temperature ranging from 200°C to 700°C. In some embodiments, calcination may be carried out as part of an integrated process prior to reduction in the same reactor as step (a).

[0062] The crystallite size of the cobalt oxide crystallites on the calcined catalyst can be below a desired upper limit of particle size (e.g., less than 20 nm, preferably less than 16 nm, e.g., less than 12 nm or less than 10 nm), or can ensure that the cobalt oxide crystallite size of the crystallites impregnated on the support material is substantially within a desired range of particle size (e.g., 6 to 12 nm, preferably 7 to 10 nm, e.g., about 8 nm).

[0063] In a preferred embodiment, the cobalt-containing Fischer-Tropsch catalyst may comprise one or more promoters, dispersing aids, strength aids and / or binders.

[0064] Preferably, the cobalt-containing Fischer-Tropsch catalyst comprises one or more promoters, preferably selected from the list consisting of ruthenium, palladium, platinum, rhodium, rhenium, manganese, chromium, nickel, iron, molybdenum, boron, tungsten, zirconium, gallium, thorium, lanthanum, cerium and mixtures thereof, preferably selected from manganese, rhenium, ruthenium and mixtures thereof.

[0065] Promoters may be used at cobalt to promoter atomic ratios of up to 250:1, and more preferably up to 125:1, such as up to 25:1, or up to 10:1. The promoted catalysts may be prepared by a variety of methods including impregnation, extrusion, precipitation, or gelation.

[0066] The promoter may be added during one or more of the steps of the catalyst preparation, including: during precipitation as a soluble compound; precipitation by incipient wetness impregnation; or after calcination of the cobalt containing precipitate.

[0067] The cobalt-containing catalyst may also be a composition additionally comprising zinc oxide, as described, for example, in US 4,826,800. Such compositions are preferably made by the preferred process described therein.

[0068] A further aspect provides a method for producing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, the method comprising:

[0069] contacting the reduced cobalt-containing Fischer-Tropsch catalyst with an oxygen-containing gas stream comprising an inert gas and 0.1% v / v to 5% v / v oxygen at a temperature of at least 0°C;

[0070] Here, the temperature of the catalyst is increased during the contacting step but is prevented from exceeding 200°C.

[0071] By using the above process, it may be possible to avoid substantial bulk oxidation of cobalt on the catalyst during passivation. For example, it is possible to prepare reduced and passivated cobalt-containing Fischer-Tropsch catalysts in which 15 to 40 mol% of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide. Preferably, 20 to 38 mol% of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide, e.g., 35 mol% or less of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide, e.g., 33 mol% or less or 30 mol% or less of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide.

[0072] Preferably, the method comprises contacting the reduced cobalt-containing Fischer-Tropsch catalyst at a temperature of at least 5°C, at least 10°C, at least 20°C, or more preferably at least 30°C.

[0073] Preferably the temperature of the catalyst is prevented from exceeding 150°C, more preferably 100°C, most preferably 80°C, for example 60°C.

[0074] It is understood that the reduced cobalt-containing Fischer-Tropsch catalyst, the oxygen-containing gas stream and the conditions during the contacting step may be substantially as defined hereinabove.

[0075] A further aspect provides a reduced and passivated cobalt-containing Fischer-Tropsch catalyst produced by the method defined hereinabove.

[0076] The reduced and passivated Fischer-Tropsch catalysts described hereinabove can be advantageously activated for Fischer-Tropsch synthesis in a reactor under a flow of synthesis gas. As will be appreciated, Fischer-Tropsch synthesis relates to the heterogeneous catalytic production of hydrocarbons from synthesis gas, for example, in the production of diesel or aviation fuels or precursors thereof. By way of illustration, the Fischer-Tropsch synthesis of alkanes from synthesis gas can be represented by Equation 1: [ka]

[0077] Typically, cobalt-containing Fischer-Tropsch catalysts containing cobalt in the form of cobalt oxide are activated by reduction to cobalt metal under flowing hydrogen at temperatures above 300°C, and in some cases above 400°C. However, by providing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst in which 15-40 mol% of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide, it has surprisingly been found that activation of the catalyst for Fischer-Tropsch synthesis can be carried out under flowing synthesis gas rather than flowing hydrogen, under milder conditions than typically used.

[0078] In a further aspect, there is provided a start-up process for a Fischer-Tropsch catalyst, the start-up process comprising the steps of: (a) providing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, wherein 15 to 40 mole percent of the cobalt on the catalyst is in the form of cobalt oxide; (b) contacting the catalyst from step (a) with a synthesis gas stream under conditions suitable to activate the catalyst for Fischer-Tropsch synthesis; (c) If necessary, adjust the temperature to the desired reaction temperature for carrying out the Fischer-Tropsch synthesis using the activated catalyst from step (b).

[0079] By providing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst in which 15-40 mol% of the cobalt on the catalyst is in the form of cobalt oxide and activating the catalyst with a syngas stream, the typically scarce and expensive hydrogen reduction equipment and conditions associated with typical catalyst activation can be avoided while retaining catalytic activity.

[0080] It has also surprisingly been found that more uniform activity across the catalyst bed can be achieved following activation. While not wishing to be bound by any particular theory, it is believed that with the present start-up process, less water is produced during catalyst activation, which reduces the effect of water from activation at the upstream end of the catalyst bed, which reduces the activity of the catalyst at the downstream end of the catalyst bed. In this manner, compressors typically used to provide high flow rates to more quickly remove water generated during catalyst activation can be avoided. Furthermore, while not wishing to be bound by any particular theory, it is believed that because less water is produced during catalyst activation, which reduces the effect of water from activation at the upstream end of the catalyst bed, which reduces the activity of the catalyst at the downstream end of the catalyst bed, the present start-up process can provide a Fischer-Tropsch process with increased productivity and / or selectivity compared to a Fischer-Tropsch process subjected to a start-up process using a typical catalyst activation, and can also provide a Fischer-Tropsch process with increased catalyst life compared to a Fischer-Tropsch process subjected to a start-up process using a typical catalyst activation.

[0081] The reduced and passivated cobalt-containing Fischer-Tropsch catalyst used in the present start-up process can be prepared by any suitable process, provided that 15-40 mol % of the cobalt on the catalyst is in the form of cobalt oxide. In particular, the reduced and passivated cobalt-containing Fischer-Tropsch catalyst can be suitably produced by the process defined earlier in this specification.

[0082] Thus, the reduced and passivated cobalt-containing Fischer-Tropsch catalyst used in the present start-up process may be substantially as defined hereinabove, with respect to the physical properties and composition of the catalyst as defined hereinabove, and / or with respect to the method of manufacture. For example, in some instances, the reduced and passivated cobalt-containing Fischer-Tropsch catalyst used in the present start-up process may be produced by the process defined hereinabove, although in some instances, the reduction and passivation steps may differ from those defined hereinabove.

[0083] It will also be understood that the reduced and passivated cobalt-containing Fischer-Tropsch catalyst used in the present start-up process may be manufactured at a different location than where the start-up process and Fischer-Tropsch synthesis are performed, and may be transported to the plant where the start-up process is performed subsequent to the manufacture of the reduced and passivated cobalt-containing Fischer-Tropsch catalyst. For example, the reduced and passivated cobalt-containing Fischer-Tropsch catalyst may be stored under a dry or inert atmosphere during transport, as described previously herein.

[0084] In addition to activating the catalyst under syngas flow, activation of the present start-up process can advantageously be performed at temperatures lower than those typically used in Fischer-Tropsch catalyst activation. Thus, in a preferred embodiment, step (b), the start-up process is carried out at temperatures below 350°C, preferably below 300°C, and more preferably below 250°C.

[0085] The synthesis gas used in the present start-up process can be any suitable synthesis gas stream. In preferred embodiments, the synthesis gas stream in step (b) comprises hydrogen and carbon monoxide in an H2:CO ratio of about 1:1 to about 10:1, e.g., about 1:1 to about 8:1 or 1:1 to about 5:1. In some preferred embodiments, the synthesis gas stream in step (b) comprises hydrogen and carbon monoxide in an H2:CO ratio of about 0.8:1 to about 3:1, preferably about 1:1 to about 2.5:1, e.g., about 1.5:1 to 2:1. Advantageously, the catalyst activation step can be carried out using a composition gas stream having the same composition as the composition gas that will subsequently be used for Fischer-Tropsch synthesis on the catalyst. In other embodiments, the synthesis gas stream in step (b) can be different in composition from that used in the subsequent Fischer-Tropsch synthesis.

[0086] The synthesis gas stream used in step (b) of the start-up process can consist essentially of synthesis gas or can be diluted. In some preferred embodiments, the synthesis gas stream used in step (b) comprises synthesis gas diluted with an inert gas, preferably nitrogen. For example, the synthesis gas stream in step (b) may comprise or essentially comprise synthesis gas and an inert gas, wherein the synthesis gas comprises at least 20% v / v of the stream, preferably at least 30% v / v, e.g., at least 40% v / v.

[0087] In step (b) of the start-up process, the synthesis gas stream is supplied at any suitable flow rate, for example, from 100 to 15,000 h -1 Preferably, in step (b), the synthesis gas stream is contacted with the catalyst at a GHSV of 500 to 12,000 h -1 The catalyst is contacted with the catalyst at a GHSV of 3,000 to 10,000 hours, preferably 3,000 to 10,000 hours. Compared to a typical Fischer-Tropsch catalytic reduction, less water is produced by the reduction of the catalyst during this start-up process, so a relatively low flow rate can be used since there is no need to drive off the produced water.

[0088] The pressure of the synthesis gas stream in step (b) of the start-up process can be any suitable pressure, and can be substantially the same as the pressure desired for the subsequent Fischer-Tropsch synthesis using the activated catalyst. For example, the pressure of the synthesis gas stream in step (b) can include increasing the pressure over time to raise the pressure from atmospheric pressure to the pressure desired for the subsequent Fischer-Tropsch synthesis. Preferably, in step (b), the synthesis gas stream is contacted with the catalyst at a pressure between atmospheric pressure and 51 bar absolute, preferably between 6 bar absolute and 51 bar absolute.

[0089] Preferably, less than 20 mole % of the cobalt on the active catalyst from step (b) of the start-up step is in the form of cobalt oxide, more preferably less than 10 mole %, for example less than 5 mole %.

[0090] In step (c) of the start-up process, the temperature is optionally adjusted to the desired reaction temperature for carrying out Fischer-Tropsch synthesis using the activated catalyst from step (b). Of course, since the start-up process may be carried out at a relatively low temperature, the temperature at which step (b) is carried out may suitably be substantially the same as the temperature used in the subsequent Fischer-Tropsch synthesis. In this manner, a specific temperature change may not be required between catalyst activation and Fischer-Tropsch synthesis. In some preferred embodiments, step (b) may comprise contacting the catalyst from step (a) with a synthesis gas stream while carrying out a suitable temperature ramp to bring the catalyst to the desired temperature for subsequent Fischer-Tropsch synthesis. For example, the catalyst temperature can be increased to about 150°C, then increased from 150°C to 160°C at a rate of 60°C / h, from 160 to 180°C at a rate of 10°C / h, from 180 to 190°C at a rate of 5°C / h, and finally increased at 1°C / h to reach the desired temperature and / or level of CO conversion.

[0091] In preferred embodiments, in step (c) of the start-up step, the temperature is adjusted to a temperature of 100° C. to 400° C., preferably 150 to 350° C., and more preferably 150 to 250° C. In some preferred embodiments, the temperature is maintained at the temperature used in step (b), for example, the temperature resulting from the temperature increase step in step (b).

[0092] In some embodiments, the start-up process further comprises performing a Fischer-Tropsch synthesis using the activated catalyst from step (b).

[0093] The Fischer-Tropsch process and / or the subsequent Fischer-Tropsch process are preferably carried out continuously in a fixed-bed, fluidized-bed, or slurry-phase reactor. In some or all embodiments, the Fischer-Tropsch process carried out using a cobalt-containing Fischer-Tropsch catalyst is a fixed-bed Fischer-Tropsch process. When using a cobalt-containing Fischer-Tropsch catalyst in a fixed-bed process, the particle size can be shaped and sized to achieve an appropriate pressure drop over the catalyst bed. One skilled in the art can determine the optimal particle size for use in such a fixed-bed reactor. Particles of the desired shape and size can be obtained, for example, by slurry extrusion, to which extrusion aids and / or binders can be added as needed.

[0094] Fischer-Tropsch synthesis using an activated catalyst can be carried out under any suitable conditions. For example, the volume ratio of hydrogen to carbon monoxide in the synthesis gas is preferably in the range of 0.5:1 to 5:1, more preferably 1:1 to 3:1, and most preferably 1.5:1 to 2.5:1. The synthesis gas stream during Fischer-Tropsch synthesis may be the same as that used in step (b) of the start-up process defined above, and also contains other gaseous components such as nitrogen, carbon dioxide, water, methane, and other saturated and / or unsaturated light hydrocarbons, each preferably present at a concentration of less than 30% by volume. The temperature of the Fischer-Tropsch reaction is preferably in the range of 100 to 400°C, more preferably 150 to 350°C, and most preferably 150 to 250°C. The pressure is preferably in the range of atmospheric pressure to 100 bar absolute, more preferably 5 to 75 bar absolute, and most preferably 10 to 50 bar absolute.

[0095] The present start-up process may advantageously be carried out using a syngas stream to activate the catalyst, although hydrogen may also be used to activate the catalyst under milder conditions than typically used. Thus, a further aspect provides a start-up process for a Fischer-Tropsch catalyst, the start-up process comprising the steps of: (a) providing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, wherein 15 to 40 mole percent of the cobalt on the catalyst is in the form of cobalt oxide; (b) contacting the catalyst from step (a) with a reducing gas stream at a temperature of less than 300°C under conditions suitable to activate the catalyst for Fischer-Tropsch synthesis; (c) If necessary, adjust the temperature to the desired reaction temperature for carrying out the Fischer-Tropsch synthesis using the activated catalyst from step (b).

[0096] Specifically, apart from using a reducing gas instead of synthesis gas, the start-up process may be substantially as defined hereinabove.

[0097] Preferably, the reducing gas is hydrogen. For example, the reducing gas stream may comprise at least 80% v / v hydrogen, preferably at least 90% v / v hydrogen, e.g., the reducing gas may consist essentially of hydrogen.

[0098] In a preferred embodiment, the temperature at which the catalyst from step (a) is contacted with the reducing gas stream in step (b) may be below 250°C.

[0099] A further aspect provides the use of a reduced and passivated cobalt-containing Fischer-Tropsch catalyst as defined herein above for improving CO conversion and / or productivity in a Fischer-Tropsch synthesis process, wherein the reduced and passivated catalyst is activated by contacting the catalyst with a synthesis gas stream and / or at a temperature below 300° C. Preferably, the use comprises activating the catalyst under process conditions as defined herein above.

[0100] The invention will now be described by reference to the following non-limiting examples and accompanying figures: [Brief explanation of the drawings]

[0101] [Figure 1] FIG. 1 shows a schematic diagram of an arrangement of four catalyst beds connected in series for reducing a catalyst according to the present invention. [Figure 2] 1 shows a schematic diagram of an arrangement of four catalyst beds connected in parallel for carrying out Fischer-Tropsch synthesis according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0102] example Catalyst synthesis and passivation The initial catalyst material was prepared by impregnating a P25 titania support with a solution containing cobalt nitrate hexahydrate and manganese acetate tetrahydrate, resulting in a catalyst material containing 10 wt. % cobalt and 1 wt. % manganese on the support. The support was shaped and impregnated with the active components, then dried and calcined.

[0103] A series of catalysts were passivated according to Table 1 below. The catalysts were prepared using the above catalyst materials by first contacting 10 g of catalyst in a fixed-bed tubular reactor with 100% hydrogen flow at 300°C and atmospheric pressure for 15 hours to reduce the cobalt on the catalyst material, followed by conditioning to the specified temperature. The catalysts were then passivated for 2000 h. -1 The catalyst was contacted with the oxygen-containing gas stream at GHSV of 1000 and atmospheric pressure for 2 hours. The temperature of the catalyst was monitored by a thermocouple in the catalyst bed.

[0104] The catalyst samples were then analyzed by temperature-programmed reduction (TPR) to determine the percentage of cobalt oxide present in the catalyst sample. TPR tests were performed on approximately 50 mg of catalyst sample using a Micromeritics 2920 AutoChem II analyzer coupled with an integrated thermal conductivity detector (TCD) and a Cirrius 2 quadrupole mass spectrometer. The sample was loaded into a quartz glass U-tube, dried under flowing argon, and heated from room temperature to 110°C at 5°C / min, where the temperature was held for 15 minutes. The sample was then cooled to room temperature under argon. TPR analysis was performed using 4% v / v hydrogen in argon (30 ml / min) heated from room temperature to 550°C at a rate of 5°C / min. [Table 1]

[0105] As can be seen in Table 1, the temperature and oxygen content of the oxygen-containing stream can be varied to change the proportion of cobalt oxide on the reduced and passivated catalyst. Fischer-Tropsch synthesis Example 6 (Comparative)

[0106] 1.5 ml of the calcined catalyst not passivated according to the procedure described above was loaded into a microreactor and heated under H flow (15 h, 300 °C, 100% H, 1 bar absolute, 5000 h -1 The catalyst was reduced under GHSV (1000 psi). After cooling, the gas flow over the catalyst was switched to a mixture of synthesis gas (H2 / CO = 1.8) and 60% nitrogen, maintaining a pressure of 43 bar absolute. The temperature was increased from 130 °C at 10 °C / h until approximately 60% CO conversion (approximately 215 °C) was reached. Example 7

[0107] The procedure of Example 6 was followed, except that the passivated catalysts according to Examples 1 and 5 were used and the reduction under hydrogen was not carried out before contacting the catalyst with a synthesis gas stream and increasing the temperature from 130°C to about 215°C at 10°C / hour.

[0108] Table 2 shows the steady-state Fischer-Tropsch synthesis results for the catalysts of Examples 1 and 5, and Example 6, after approximately 400-450 hours on stream. [Table 2]

[0109] As can be seen in Table 2, the reduced and passivated catalyst activated under flowing syngas for use in the Fischer-Tropsch reaction surprisingly exhibits activity comparable to that of the catalyst reduced in situ with hydrogen.

[0110] Further Fischer-Tropsch reactions were also carried out using a further catalyst passivated according to the above procedure with a cobalt oxide content of 39%. The catalyst was found to be active for Fischer-Tropsch synthesis, but exhibited relatively lower activity than the catalysts of Examples 1 and 5 above. Catalyst Bed Uniformity Test

[0111] Using a four connected catalyst bed configuration, a calcined cobalt-containing catalyst and a reduced and passivated catalyst according to the present disclosure (50% H2 / N2, GHSV 8000hr-1 Catalyst bed uniformity was tested for the following three tests: a calcined catalyst reduced at 300°C, atmospheric pressure; and a calcined catalyst passivated with 1% O2 / N2 at <30°C. Three tests were performed according to the following general procedure, as shown in Table 3 below. One test was performed using the calcined catalyst activated under 100% H2 (Example 8), a further test using the calcined catalyst activated under 50% H2 / N2 (Example 9), and a final test using the reduced and passivated catalyst activated under 50% H2 / N2 (Example 10). catalyst activation

[0112] To reduce the cobalt content of four fixed beds connected in series as shown in Figure 1, a gas containing stream (either 100% H or 50% H / N) was introduced from bed 1 to beds 2–4 (GHSV 8000 h). -1 absolute, 1 bar absolute, 300°C) was passed over the catalogue bed. Fischer-Tropsch synthesis

[0113] After performing the above activation and cooling the catalyst bed, a mixture of synthesis gas (H2 / CO = 1.8) in 51% nitrogen was added to the catalyst bed. -1 , 31 bar absolute pressure) to the catalyst beds in parallel. In this way, it was possible to analyze the activity of each of the catalyst beds in relation to its relative position during activation. The temperature was increased to 215°C, and the steady-state CO conversion at 215°C was recorded for each of the four catalyst beds and is shown in Table 3 below. The temperature in each catalyst bed required to reach matching conversion was also measured and is shown in Table 3 below. [Table 3]

[0114] As can be seen from Table 3, when a catalyst reduced and passivated according to the present disclosure is used (Example 10), the activity across the four catalyst beds is more uniform than when a calcined catalyst is used. By analogy, a reactor using a single catalyst bed can also be expected to show the same trend of improved catalyst bed uniformity from the upstream end to the downstream end of the bed.

[0115] Without wishing to be bound by any particular theory, it is believed that by using a reduced and passivated catalyst according to the present disclosure, the effect of water generated during catalyst activation on the downstream end of the catalyst bed is minimized compared to conventional catalyst reduction.

Claims

1. 1. A method for producing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, comprising: (a) contacting a cobalt-containing Fischer-Tropsch catalyst with a reducing gas under conditions suitable to produce a reduced cobalt-containing Fischer-Tropsch catalyst; (b) adjusting the temperature of the reduced cobalt-containing Fischer-Tropsch catalyst to a temperature in the range of 0°C to 100°C under a non-oxidizing atmosphere; (c) contacting the reduced cobalt-containing Fischer-Tropsch catalyst with an oxygen-containing gas stream containing from 0.1% v / v to 5% v / v oxygen, the remainder being an inert gas, at a temperature in the range of from 0°C to 100°C to produce a reduced and passivated cobalt-containing Fischer-Tropsch catalyst; In step (c), the amount of oxygen in the oxygen-containing gas stream, the temperature, and the time are selected and maintained to produce a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, wherein 20 to 35 mole percent of the cobalt on the catalyst is in the form of cobalt oxide; and The process comprises the step of: (c) preventing the temperature of the reduced cobalt-containing Fischer-Tropsch catalyst from exceeding 100°C; and (d) preventing the temperature of the reduced cobalt-containing Fischer-Tropsch catalyst from exceeding 100°C.

2. 10. The method of claim 1, wherein the temperature selected and maintained in step (c) is the temperature at which the catalyst is conditioned in step (b).

3. 3. The process of claim 1 or 2, wherein up to 32 mole percent of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide.

4. A process according to any one of claims 1 to 3, wherein the contacting step (c) comprises contacting the reduced cobalt-containing Fischer-Tropsch catalyst with an oxygen-containing gas stream at a temperature of from 5°C to 100°C.

5. A method according to any one of claims 1 to 4, wherein the oxygen-containing gas stream comprises between 0.2% v / v and 2.5% v / v oxygen.

6. A process according to any one of claims 1 to 5, wherein the oxygen-containing gas stream is contacted with the continuously reduced cobalt-containing Fischer-Tropsch catalyst in a fixed bed reactor.

7. The oxygen-containing gas flow is －１ 7. The process of claim 6, wherein the reduced cobalt-containing Fischer-Tropsch catalyst is contacted at a GHSV of 0.1 to 1.

0.

8. 8. The process of any one of claims 1 to 7, wherein the contacting step (c) is carried out at a pressure of from 1 bar (absolute) to 31 bar (absolute).

9. The amount and temperature of oxygen in the oxygen-containing gas stream are (i) carrying out steps (a)-(c) of the method for a Fischer-Tropsch catalyst having a predetermined composition, at a first temperature under a predetermined set of process conditions, and using an oxygen-containing gas stream having a first oxygen content to produce a test catalyst; (ii) determining the percentage of cobalt on the test catalyst that is in the form of cobalt oxide by performing a temperature programmed reduction of the test catalyst; 9. A method according to any one of claims 1 to 8, further comprising the step of (iii) repeating steps (i) and (ii) at a second temperature different from the first temperature, and / or a second oxygen content different from the first oxygen content, if the proportion of cobalt on the test catalyst in the form of cobalt oxide is outside the range of 20 to 35 mol %.

10. A process according to any one of claims 1 to 9, wherein the reduced cobalt-containing Fischer-Tropsch catalyst comprises one or more promoters.

11. 11. The method of claim 10, wherein the one or more promoters are selected from ruthenium, palladium, platinum, rhodium, rhenium, manganese, chromium, nickel, iron, molybdenum, boron, tungsten, zirconium, gallium, thorium, lanthanum, cerium, and mixtures thereof.

12. 12. The process of any one of claims 1 to 11, wherein the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is stored under a dry atmosphere and / or the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is coated with a wax or hydrocarbon.

13. 13. The process of claim 12, wherein in step (a) the cobalt-containing Fischer-Tropsch catalyst is reduced by contacting the catalyst with a hydrogen stream at a temperature of from 200°C to 600°C.

14. 14. The process of any one of claims 1 to 13, further comprising contacting the reduced and passivated cobalt-containing Fischer-Tropsch catalyst with a synthesis gas stream under conditions suitable to activate the catalyst for Fischer-Tropsch synthesis.

15. 1. A start-up method for a Fischer-Tropsch catalyst comprising: (a) providing a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, wherein 20 to 35 mole percent of the cobalt on said catalyst is in the form of cobalt oxide; (b) contacting the catalyst from step (a) with a synthesis gas stream under conditions suitable to activate the catalyst for Fischer-Tropsch synthesis; (c) optionally adjusting the temperature to the desired reaction temperature for carrying out a Fischer-Tropsch synthesis using the activated catalyst from step (b).

16. 16. The method of claim 15, wherein step (b) is carried out at a temperature of less than 350°C.

17. The synthesis gas stream in step (b) is a mixture of hydrogen and carbon monoxide in a ratio of 1:1 to 3:

1. ２ 17. The method of claim 15 or 16, comprising the following ratio:

18. A process according to any one of claims 15 to 17, wherein less than 10 mole percent of the cobalt on the activated catalyst from step (b) is in the form of cobalt oxide.

19. In step (b), the synthesis gas stream is subjected to a process for 500 to 10,000 h -1 The method of any one of claims 15 to 18, wherein the catalyst is contacted at a GHSV of

20. A process according to any one of claims 15 to 19, wherein in step (b) the synthesis gas stream is contacted with the catalyst at a pressure of from atmospheric pressure to 51 bar (absolute).

21. 21. The method according to any one of claims 15 to 20, wherein in step (c) the temperature is adjusted to a temperature of from 100°C to 400°C, or the temperature in step (c) is maintained at the temperature used in step (b).

22. A process according to any one of claims 15 to 21, wherein up to 32 mole % of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide.

23. 23. A process according to any one of claims 15 to 22, wherein the reduced and passivated cobalt-containing Fischer-Tropsch catalyst in step (a) is a supported catalyst, and optionally the reduced and passivated cobalt-containing Fischer-Tropsch catalyst in step (a) comprises one or more promoters as defined in claim 11.

24. A process according to any one of claims 15 to 23, wherein the reduced and passivated cobalt-containing Fischer-Tropsch catalyst in step (a) is produced by a process according to any one of claims 1 to 13.

25. 25. The method of any one of claims 15 to 24, wherein the reduced and passivated cobalt-containing Fischer-Tropsch catalyst provided in step (a) is produced at a location different from the location at which the start-up method is carried out.

26. 26. The method of claim 25, wherein the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is stored under a dry or inert atmosphere during transport.

27. 16. Use of a reduced and passivated cobalt-containing Fischer-Tropsch catalyst, wherein 20 to 35 mole % of the cobalt on the reduced and passivated cobalt-containing Fischer-Tropsch catalyst is in the form of cobalt oxide, to improve CO conversion and / or productivity in a Fischer-Tropsch synthesis process, wherein the reduced and passivated catalyst is activated by contacting the catalyst with a synthesis gas stream.

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