Start of Fischer-Tropsch synthesis

Abstract

The present disclosure relates generally to methods for initiating a Fischer-Tropsch synthesis. In particular, the present application provides a method for initiating a Fischer-Tropsch synthesis comprising: (i) providing a reaction zone having a temperature of 140° C. or less; and (ii) supplying N 2 at a pressure in the range of 2 barg to 10 barg. 2 and (iii) purging the catalyst in the reaction zone with a purge gas comprising H in a ratio of 1:1 to 3:1 at a pressure of not more than 20 barg and a temperature of not more than 140°C. 2 and CO; then (iv) heating the reaction zone to a temperature of at least 200° C.; and (v) pressurizing the reaction zone to a pressure in the range of from 30 barg to 45 barg.

Description

[Technical field]

[0001] The present disclosure relates to a Fischer-Tropsch process, and in particular to techniques for starting a Fischer-Tropsch process. [Background technology]

[0002] The conversion of synthesis gas (i.e., a mixture of carbon monoxide and hydrogen, also known as syngas) to hydrocarbons via the Fischer-Tropsch process has been known for decades, but historically has lagged in performance compared to other hydrocarbon synthesis techniques. As alternative energy sources grow in importance, there has been a resurgence of interest in the Fischer-Tropsch (FT) process, as it enables a direct and environmentally acceptable route to high quality fuels and feedstock chemicals.

[0003] The FT process is known to produce linear hydrocarbons for use in fuels, as well as oxygenates that are useful in fuels and can also serve as valuable feedstock chemicals. Hydrocarbon fuels derived from the FT process can better meet increasingly stringent environmental regulations compared to fuels produced in conventional refineries, since FT-derived fuels typically have lower sulfur, nitrogen, and aromatics content that contribute to the emission of powerful pollutants such as SO2, NOx, and particulates. Alcohols derived from the FT process often have higher octane numbers than hydrocarbons and therefore burn more completely, thereby reducing the environmental impact of such fuels. The resulting alcohols and other oxygenates can also be used as reagents in other processes, such as the synthesis of lubricants.

[0004] Various transition metals have been identified as catalytically active in the conversion of synthesis gas to hydrocarbons and their oxygenated derivatives. In particular, cobalt, nickel, and iron have been investigated, often in combination with support materials, the most common of which are alumina, silica, and carbon.

[0005] In a typical preparation of a supported cobalt-containing FT synthesis catalyst, a solid support material is contacted with a solution of a soluble cobalt compound, such as cobalt nitrate. The impregnated support is then calcined and / or oxidized to form cobalt oxides, typically one or more of CoO, Co2O3, or Co3O4. However, such oxides typically have low FT catalytic activity and must be reduced to form the preferred catalytically active species of cobalt metal.

[0006] During start-up, the reduced catalyst is contacted with the synthesis gas at high temperature and / or pressure in the FT reactor until the desired steady-state operation is achieved. During start-up, the reaction efficiency may be undesirably low and the product mixture may generally differ from that from the steady-state operation. After start-up, i.e., after the desired steady-state operation is achieved, the reactor is operated continuously at steady-state conditions for an extended period of time. Because start-up conditions may vary significantly from the steady-state conditions, poor reactor control may result in inefficient energy use, poor product distribution, and even damage to the reactor or catalyst.

[0007] Therefore, there is a need to develop improved protocols for the start-up of Fischer-Tropsch synthesis reactors. Summary of the Invention [Problem to be solved by the invention]

[0008] We have discovered a method for initiating a Fischer-Tropsch synthesis that allows for superior control of reactor conditions such as pressure and temperature. This results in increased process efficiency during start-up and prevents dangerous thermal runaway from occurring due to exothermic contact of the synthesis gas with fresh catalyst. [Means for solving the problem]

[0009] Thus, in one aspect, the disclosure provides a process for the initiation of a Fischer-Tropsch synthesis in a reaction zone having a catalyst disposed therein, the catalyst being in a reduced form, and the process comprising: (i) providing a temperature in said reaction zone of no more than 160° C.; and (ii) purging the reaction zone at a temperature of 160° C. or less with a purge gas comprising N2 at a pressure in the range of 2 barg to 15 barg; and (iii) contacting the catalyst in the reaction zone with a gaseous reaction mixture comprising H2 and CO in a ratio in the range of 1:1 to 3:1 at a pressure not exceeding 45 barg and a temperature not exceeding 160°C; and then, while in contact with the gaseous reaction mixture, (iv) heating said reaction zone to a temperature of at least 200° C.; (v) pressurizing the reaction zone to a pressure in the range of from 25 barg to 45 barg.

[0010] In various embodiments of the process of the present disclosure, the heating in step (iv) is carried out at a number of different heating rates. (a) heating at a temperature less than 160°C at a rate ranging from 10°C / hour to 60°C / hour; (b) heating at a temperature in the range of 160°C to 180°C at a rate in the range of 2°C / hour to 30°C / hour; (c) heating at a temperature in the range of 180°C to 220°C at a rate in the range of 0.5°C / hour to 7°C / hour;

[0011] Other aspects of the present disclosure will be apparent to those of skill in the art in view of the following description. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a reactor suitable for use in the processes described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The reactor 110 is loaded with catalyst 120. Gas (e.g., CO, H2, inert gases) is introduced through inlet 101, optionally flows in a once-through configuration, and exits the system at 104, with hydrocarbon products being removed through outlet 104 for further processing. Unreacted gases are optionally removed through recycle outlet 102 via separator 130, and are optionally recycled back to inlet 101 through recycle feed 103.

[0014] The present disclosure relates to techniques for starting up a Fischer-Tropsch synthesis process in which a mixture of hydrogen and carbon monoxide is converted to hydrocarbons. In a typical Fischer-Tropsch process, a supported cobalt oxide catalyst precursor is reduced with hydrogen at high temperatures (typically above 300° C.). If the reduction is performed ex situ, the catalyst is transferred to a reactor under inert conditions. If the reduction is performed in situ, the catalyst is cooled to the Fischer-Tropsch synthesis reaction temperature and then the catalyst is contacted with synthesis gas. A stream of synthesis gas (typically a mixture of H2 and CO, optionally with CO2 and nitrogen as a diluent) is fed to the reactor to initiate the reaction process. During start-up, the temperature and pressure are increased to ultimately provide the desired reaction conditions, which are typically maintained throughout the process.

[0015] The inventors have found that contacting a freshly reduced Fischer-Tropsch catalyst with synthesis gas can result in a dangerous exotherm as carbon monoxide and hydrogen are exothermically converted to hydrocarbons. Over time, the catalyst loses the activity typically associated with a freshly reduced catalyst and the process enters a steady-state regime where reaction rates are slower and less heat is generated. Unless mitigated, the exotherm during start-up can result in a dangerous increase in temperature within the Fischer-Tropsch reactor, resulting in potential damage to the reactor and catalyst, as well as undesirable energy waste.

[0016] One way to suppress this exotherm is to introduce syngas with a significant proportion of an inert gas, such as N2 gas. The syngas proportion can be low at first and then slowly increased as the catalyst loses activity and transitions from the start-up to the steady-state operating regime. This approach of ramping the syngas concentration is reasonable for small laboratory-scale reactors. However, in full-scale industrial Fischer-Tropsch plants, this solution is less practical. On a large scale, it can require up to 5000 Nm at pressures above 10 barg. 3 / m 3 Compressors capable of handling pressures in excess of 1.5 kPa are utilized. In absolute terms, a typical reactor with 1000 reactor tubes requires a compressor of 20 m 3 Catalysts exceeding 10 ...

[0017] Therefore, we explored an alternative start-up procedure for initiating a Fischer-Tropsch synthesis that could avoid substantial changes in the syngas supply and also avoid the generation of dangerous exotherms.

[0018] Thus, in one aspect, the present disclosure provides a process for initiating a Fischer-Tropsch synthesis in a reaction zone having a reduction catalyst disposed therein, the process comprising: (i) providing a temperature in said reaction zone of no more than 160° C.; and (ii) purging the reaction zone at a temperature of 160° C. or less with a purge gas comprising N2 at a pressure in the range of 2 barg to 15 barg; and (iii) contacting the catalyst in the reaction zone with a gaseous reaction mixture comprising H2 and CO in a ratio in the range of 1:1 to 3:1 at a pressure not exceeding 45 barg and a temperature not exceeding 160°C; and then, while in contact with the gaseous reaction mixture, (iv) heating said reaction zone to a temperature of at least 200° C.; (v) pressurizing the reaction zone to a pressure in the range of from 25 barg to 45 barg.

[0019] As described in more detail below, various reaction systems can be used in carrying out the processes described herein, and those skilled in the art will adapt conventional systems as necessary. As known to those skilled in the art, suitable means for controlling reactor temperature during activation and start-up can be used, including electrical heating, direct heating of the reactor tubes with steam, or indirect heating with steam via an eductor or jet pump arrangement to heat a circulating water circuit around the reactor tubes. An example of a reaction system for use in carrying out the process of the present disclosure is shown in the schematic diagram of FIG. 1. The reactor 110 is charged with reduced catalyst 120. Synthesis gas is introduced through inlet 101, and the hydrocarbon products are removed through outlet 104 and further processed. Unreacted synthesis gas, and optionally light hydrocarbons, are removed through recycle outlet 102 and recycled to inlet 101 through recycle feed 103.

[0020] Thus, the reaction zone (including, for example, reactor 110 described above) has a reduction catalyst disposed therein (for example, reduction catalyst 120 described above). One skilled in the art can provide the reduction catalyst using conventional methods in the art, for example, by reducing an oxide catalyst precursor with hydrogen. Such reduction can be performed in situ, i.e., in the reactor in which the subsequent Fischer-Tropsch synthesis takes place, or can be performed ex situ, i.e., in a separate reactor, desirably loaded into the FT reactor under inert conditions.

[0021] As discussed above, the reaction zone in which the reduced catalyst is disposed has a temperature of 140° C. or less. When the catalyst is reduced ex situ, the catalyst is often at a temperature of 140° C. or less when introduced into the reaction zone. However, when the reaction zone having the reduced catalyst therein exceeds 140° C., e.g., when the catalyst is reduced in situ, the reaction zone may be cooled to a temperature of 140° C. or less. For example, in various embodiments described elsewhere herein, providing the reaction zone includes cooling the reaction zone from a temperature of at least 150° C. to a temperature of 140° C. or less. In various embodiments described elsewhere herein, the reaction zone in step (i) is cooled from a temperature of at least 160° C. (e.g., at least 170° C., or at least 180° C., or at least 190° C., or at least 200° C.).

[0022] If there is cooling in step (i), it can be carried out in any desired manner, for example, using various gases. In various embodiments described elsewhere herein, the cooling occurs in the presence of a gaseous mixture comprising H2 and N2. In certain embodiments described elsewhere herein, the gaseous mixture comprises at least 5% H2. For example, the gaseous mixture may comprise at least 10% H2, or at least 15% H2, or at least 25% H2. In certain embodiments, the gaseous mixture in the cooling step comprises less than 5% CO, for example less than 1% CO or less than 0.1% CO, or is substantially free of CO.

[0023] The reaction zone in step (i) may be provided at various temperatures up to 140°C. For example, in various embodiments described elsewhere herein, the temperature of the reaction zone in step (i) is up to 130°C, e.g., up to 120°C. In various embodiments described elsewhere herein, the reaction zone in step (i) is at a temperature in the range of 80°C to 140°C. For example, in various particular such embodiments, the reaction zone in step (i) is at a temperature in the range of 80°C to 130°C, or 80°C to 120°C. In various particular such embodiments, the reaction zone in step (i) is at a temperature in the range of 100°C to 140°C, e.g., 100°C to 130°C, or 100°C to 120°C. In various particular such embodiments, the reaction zone in step (i) is at a temperature in the range of 80°C to 160°C, e.g., 110°C to 130°C.

[0024] The reaction zone is then purged with a purge gas comprising N2 at a pressure ranging from 2 barg to 15 barg. The purge gas acts to remove hydrogen and any volatile reduction products or water from the reduced catalyst before it contacts the synthesis gas. In various embodiments described elsewhere herein, the purge gas comprises at least 90% N2, e.g., at least 95% N2, or at least 99% N2, or is substantially pure N2. In various embodiments described elsewhere herein, the purge gas comprises 5% H2 by volume or less (e.g., 1% H2 by volume or less, or 0.1% H2 by volume or less, or 0.01% H2 by volume or less, or substantially no H2). Purging is performed for a time sufficient to substantially remove undesired reactants. For example, in various embodiments described elsewhere herein, the purging can be carried out for a time ranging from 0.1 hours to 24 hours, e.g., from 0.5 hours to 24 hours, or from 1 hour to 24 hours, or from 1 hour to 12 hours, or from 1 hour to 6 hours.

[0025] The purge step is operated at a pressure above ambient pressure to efficiently drive off undesirable species. The purge step also serves as an initial pressurization step for the catalyst in preparation for contact with the synthesis gas. Thus, the purge step (ii) is operated at a pressure in the range of 2 barg to 15 barg (e.g., in the range of 2 barg to 12 barg, or 2 barg to 10 barg, or 3 barg to 12 barg, or 3 barg to 10 barg, or 4 barg to 12 barg, or 4 barg to 10 barg).

[0026] After the purging step (ii), the catalyst is contacted in the reaction zone with a gaseous reaction mixture comprising both H2 and CO in a H2:CO volume ratio ranging from 1:1 to 3:1. One skilled in the art will select the desired gaseous reaction mixture source based on, inter alia, the H2:CO volume ratio desired for use in the final FT synthesis process at steady state. For example, in various embodiments described elsewhere herein, the gaseous reaction mixture comprises H2 and CO in a H2:CO volume ratio ranging from 1:1 to 2.5:1, or 1:1 to 2:1, or 1.5:1 to 3:1, or 1.5:1 to 2.5:1, or 1.5:1 to 2:1, or 2:1 to 3:1, or 2:1 to 3:1. In various embodiments described elsewhere herein, the gaseous reaction mixture comprises H2 and CO in a H2:CO volume ratio ranging from 1.5:1 to 2.5:1.

[0027] The gaseous reaction mixture may also contain other gases, for example the gaseous reaction mixture may contain carbon dioxide in an amount of 20% or less, such as 10% or less, or 5% or less.

[0028] Advantageously, the methods described herein allow for the utilization of a relatively high percentage of H2 and CO in the gaseous reaction feed at start-up. In various embodiments described elsewhere herein, the gaseous reaction mixture comprises at least 20% by volume of H2 and CO (i.e., the combined percentage of H2 and CO is at least 20% by volume). For example, in various embodiments described elsewhere herein, the gaseous reaction mixture comprises at least 30% by volume of H2 and CO (e.g., at least 35% by volume of H2 and CO). In various embodiments described elsewhere herein, the gaseous reaction mixture comprises at least 40% by volume of H2 and CO (e.g., at least 45% by volume of H2 and CO).

[0029] Nitrogen gas can be used as an inert gas in the gaseous reaction mixture. In certain embodiments described elsewhere herein, the gaseous reaction mixture further comprises N2 in an amount of up to 80% by volume, e.g., up to 70% by volume, or up to 60% by volume, or up to 50% by volume. For example, in certain embodiments, the gaseous reaction mixture comprises N2 in an amount ranging from 20% by volume to 80% by volume, e.g., from 20% by volume to 70% by volume, or from 20% by volume to 60% by volume, or from 30% by volume to 80% by volume, or from 30% by volume to 70% by volume, or from 30% by volume to 60% by volume, or from 40% by volume to 80% by volume, or from 40% by volume to 70% by volume, or from 40% by volume to 60% by volume.

[0030] The total amount of H2, CO and N2 in the gaseous reaction mixture of the processes described elsewhere herein is desirably high, for example at least 80% by volume, or at least 90% by volume, or at least 95% by volume, or at least 99% by volume.

[0031] Advantageously, the processes described herein can avoid the need to slowly increase the concentrations of CO and H2 in the gaseous reaction mixture. Thus, in certain embodiments described elsewhere herein, the combined proportion of H2 and CO in the gaseous reaction mixture does not change significantly throughout the process. For example, in various embodiments described elsewhere herein, the combined proportion of H2 and CO does not change by more than 30%, e.g., more than 20%, or more than 10% throughout steps (iii)-(v).

[0032] The gaseous reaction mixture may contain other gaseous components, such as water, methane and other saturated and / or unsaturated light hydrocarbons, preferably present in a total concentration of less than 30% by volume.

[0033] It is often useful to increase reactor efficiency by recycling unreacted synthesis gas and / or incompletely reacted products, such as light hydrocarbons, to the reactor. This technique is particularly useful for processes such as those described herein and, in certain embodiments, involves contacting the catalyst with H2 and CO at a temperature below the temperature at which significant Fischer-Tropsch reactions occur. Thus, in various embodiments described elsewhere herein, step (iii) further comprises removing a recycle stream from the reaction zone and recycling at least a portion of the recycle stream to the reaction zone.

[0034] The contacting of step (iii) as described elsewhere herein is carried out at a relatively low pressure compared to steady state Fischer-Tropsch operations. Thus, in various embodiments described elsewhere herein, the contacting of step (iii) is carried out at a pressure in the range of from 5 barg to 20 barg. For example, in various such embodiments, the contacting is carried out at a pressure in the range of from 5 barg to 15 barg, or from 5 barg to 12 barg, or from 5 barg to 10 barg, or from 10 barg to 20 barg, or from 10 barg to 15 barg, or from 12 barg to 20 barg, or from 15 barg to 20 barg.

[0035] The processes described herein can be carried out at high throughput. For example, in various embodiments described elsewhere herein, the contacting in step (iii) is carried out at a GHSV ranging from 2000 hr-1 to 12,000 hr-1. For example, in various such embodiments, the contacting is carried out at a GHSV in the range of from 4000 hr-1 to 12,000 hr-1, or from 6000 hr-1 to 12,000 hr-1, or from 8000 hr-1 to 12,000 hr-1, or from 2000 hr-1 to 10,000 hr-1, or from 4000 hr-1 to 10,000 hr-1, or from 6000 hr-1 to 10,000 hr-1, or from 2000 hr-1 to 8,000 hr-1, or from 4000 hr-1 to 8,000 hr-1, or from 2000 hr-1 to 6000 hr-1.

[0036] The contacting of step (iii) described elsewhere herein is carried out at a relatively low temperature of 140° C. or less, e.g., 130° C. or less or 120° C. or less. In various embodiments described elsewhere herein, the contacting of step (iii) is carried out at a temperature in the range of 80° C. to 140° C. For example, in various particular such embodiments, the contacting of step (iii) is carried out at a temperature in the range of 80° C. to 130° C., or 80° C. to 120° C. In various particular such embodiments, the contacting of step (iii) is carried out at a temperature in the range of 100° C. to 140° C., e.g., 100° C. to 130° C., or 100° C. to 120° C. In various particular such embodiments, the contacting of step (iii) is carried out at a temperature in the range of 80° C. to 160° C., e.g., 110° C. to 130° C. The contacting of step (iii) is typically carried out at a temperature close to the temperature of step (i), e.g., within 10° C. of such a temperature.

[0037] While in contact with the gaseous reaction mixture, the reaction zone is then heated to a temperature of at least 200°C and pressurized to a pressure in the range of 25 barg to 45 barg. Under these conditions, steady-state Fischer-Tropsch synthesis can be achieved. The heating of step (iv) and the pressurization of step (v) can be carried out in any time sequence, including simultaneously. The temperature and pressure can be selected to be those of the steady-state FT process being carried out.

[0038] Without wishing to be bound by theory, the inventors have determined that by heating the reaction zone in the presence of synthesis gas containing H2 and CO and freshly reduced catalyst, the Fischer-Tropsch synthesis activity can be increased as the temperature is increased. In turn, the increase in synthesis rate results in an increase in heat generated from the exothermic Fischer-Tropsch synthesis reaction, and the temperature must be increased carefully to prevent dangerous thermal runaway. Thus, in various embodiments described elsewhere herein, the heating step (iv) is carried out at a number of different heating rates. (a) Heating at a rate ranging from 10°C / hour to 60°C / hour to a temperature below 160°C; (b) heating at a rate ranging from 2°C / hour to 30°C / hour to a temperature ranging from 160°C to 180°C; (c) heating at a rate ranging from 0.5°C / hour to 7°C / hour to a temperature ranging from 180°C to 220°C;

[0039] In various embodiments described elsewhere herein, the method of claim 1, wherein the heating rate condition (a) comprises heating at a rate ranging from 10° C. / hr to 45° C. / hr, or from 10° C. / hr to 30° C. / hr, or from 20° C. / hr to 60° C. / hr, or from 20° C. / hr to 45° C. / hr. In various embodiments described elsewhere herein, the heating rate condition (b) comprises heating at a rate ranging from 2° C. / hr to 20° C. / hr, or from 2° C. / hr to 15° C. / hr, or from 4° C. / hr to 30° C. / hr, or from 4° C. / hr to 20° C. / hr, or from 4° C. / hr to 15° C. / hr. In various embodiments described elsewhere herein, heating rate condition (c) includes heating at a rate ranging from 0.5° C. / hr to 5° C. / hr, or from 0.5° C. / hr to 4° C. / hr, or from 1° C. / hr to 7° C. / hr, or from 1° C. / hr to 5° C. / hr, or from 1° C. / hr to 4° C. / hr, or from 2° C. / hr to 7° C. / hr, or from 2° C. / hr to 5° C. / hr, or from 2° C. / hr to 4° C. / hr.

[0040] Once the temperature at which the Fischer-Tropsch reaction begins (typically about 150-180° C.) is reached, a hydrocarbon product composition begins to form in the reaction zone, and once the Fischer-Tropsch reaction reaches its steady state operation (e.g., under the conditions of steps (iv) and (v)), the hydrocarbon product composition continues to form to advantageously provide the desired products. Thus, in various embodiments described elsewhere herein, the process includes, after steps (iv) and (v), (vi) conducting a Fischer-Tropsch synthesis; and withdrawing a hydrocarbon product composition from the reaction zone, the hydrocarbon composition comprising one or more of methane, C5+ hydrocarbons, and oxygenates.

[0041] Various embodiments of the temperature ramp in step (iii) or step (iv) may include a dwell or hold at the ramped temperature to allow for catalyst stabilization, catalyst conditioning or wax / hydrocarbon accumulation in the catalyst pores.

[0042] Subject to the limitations set forth herein, one of skill in the art can adapt conventional Fischer-Tropsch processes to arrive at the methods of the present disclosure. For example, the temperature of the Fischer-Tropsch synthesis may suitably range from 200 to 400°C, e.g., 200 to 300°C, or 210 to 400°C, or 210 to 300°C, or 220 to 400°C, or 220 to 300°C. In various embodiments described elsewhere herein, the temperature of the Fischer-Tropsch synthesis may range from 200 to 250°C, e.g., 200 to 240°C, or 200 to 230°C, or 200 to 220°C, or 210 to 250°C, or 210 to 240°C, or 210 to 230°C, or 220 to 250°C, or 220 to 240°C, or 230 to 250°C. The pressure of the reaction may suitably be in the range of from 25 to 45 barg, for example, from 30 to 40 barg, or from 30 to 35 barg, or from 35 to 45 barg, or from 35 to 40 barg, or from 40 to 45 barg.

[0043] The Fischer-Tropsch synthesis reaction can be carried out in any suitable type of reactor, for example, a fixed bed reactor, a slurry bed reactor, or a CANS™ reactor. With particular reference to CANS reactors, the passivated catalyst materials described herein can be packaged (e.g., off-site and then transported to the reactor site) in modular catalyst containers suitable for use in the reactor tubes of a CANS reactor.

[0044] The hydrocarbon composition may vary based on changes in process conditions as known in the art. In certain embodiments, the hydrocarbon composition comprises hydrocarbons (e.g., linear, branched, saturated or unsaturated) and oxygenated derivatives thereof. Examples of the oxygenated derivatives include hydrocarbons having one or more functional groups of alcohols, aldehydes, ketones, carboxylic acids, esters, and combinations thereof. In certain embodiments described elsewhere herein, the hydrocarbon composition comprises at least one of alkanes, alkenes, and alcohols.

[0045] Those skilled in the art will be able to adapt suitable catalyst materials for use in the processes described herein. In various preferred embodiments of the processes described herein, the catalyst comprises cobalt and optionally one or more other metals or reaction modifiers disposed on a support. Supported cobalt-based materials are well known in the art and can generally be adapted for use in the processes and materials described herein.

[0046] In various embodiments described elsewhere herein, the catalytic materials described herein include cobalt in the range of 5% to 35% by weight, calculated as cobalt(0). For example, in certain embodiments described elsewhere herein, cobalt can be present in the range of 7 to 35% by weight, or 10 to 35% by weight, or 5 to 25% by weight, or 7 to 25% by weight, or 10 to 25% by weight, or 5 to 20% by weight, or 7 to 20% by weight, or 10 to 20% by weight.

[0047] The catalytic materials described herein can include other metal species, e.g., as promoters. For example, in certain embodiments described elsewhere herein, the catalytic materials include manganese in an amount ranging from, e.g., 15 wt.% or less, e.g., 12 wt.% or less, or 10 wt.% or less, or 7 wt.% or less, calculated as manganese(0). In certain such embodiments, the catalytic materials include manganese in an amount ranging from 0.1 to 15 wt.%, e.g., 0.5 to 12 wt.%, or 0.5 to 10 wt.%. Of course, in other embodiments, manganese is substantially absent (e.g., less than 0.1 wt.% or less than 0.5 wt.% manganese is present).

[0048] A variety of support materials are known in the art and can be selected based on the exact requirements of the FT reactor or other chemical, mechanical or economic requirements. In certain embodiments described elsewhere herein, the support comprises at least one of titanium oxide, zirconium oxide, cerium oxide, aluminum oxide, silicon oxide, and zinc oxide. In certain embodiments, the support comprises exactly one of titanium oxide, zirconium oxide, cerium oxide, aluminum oxide, silicon oxide, and zinc oxide.

[0049] The catalyst can be prepared using conventional methods in the art. In some embodiments, cobalt is introduced onto the support by introducing a solution containing a soluble cobalt salt (e.g., cobalt nitrate) to the support, and the combination is calcined and / or oxidized to provide insoluble cobalt particles (e.g., as cobalt oxide) on the support. In some embodiments, the first catalytic material comprises a combination of calcined metals (e.g., including calcined cobalt) deposited on the support. In certain embodiments, the cobalt of the first catalytic material (i.e., at least a portion of the cobalt, up to all of the cobalt, e.g., at least 50%, at least 75%, or at least 90%) is in the form of at least one of cobalt oxide and cobalt hydroxide. For example, the cobalt can be cobalt oxide (e.g., CoO, Co3O4, or Co2O3, or a combination thereof), or cobalt hydroxide (e.g., Co(OH)2 or Co(OH)3, or a combination thereof), or a combination of cobalt oxide and cobalt hydroxide.

[0050] In certain embodiments, the catalyst must be substantially reduced to produce a reduced catalytic material. This process results in at least a portion of the cobalt being converted to cobalt metal. Desirably, the reduction results in at least 50% of the cobalt being provided as cobalt(0), e.g., at least 75% or at least 90% of the cobalt being provided as cobalt(0). Those skilled in the art can use conventional methods to reduce cobalt catalytic materials (e.g., cobalt oxide or cobalt hydroxide based materials) to the metallic form. In certain embodiments described elsewhere herein, the first reducing agent is hydrogen gas, H2. Hydrogen gas may be mixed with other gases, such as inert carrier gases. Examples of such inert carrier gases include nitrogen, carbon dioxide, argon, or helium. Hydrogen gas may be mixed with carbon monoxide, with or without one or more additional carrier gases. In certain embodiments, the reduction is accomplished by contacting the first catalytic material with a first reducing gas, the first reducing gas comprising a first reducing agent, the first reducing gas comprising at least 50% H by volume (e.g., at least 60% by volume, or at least 70% by volume, or at least 80% by volume, or at least 90% by volume, or at least 95% by volume, or essentially 100% by volume H).

[0051] The reduction of the catalytic material to provide a reduced catalytic material is carried out at a first temperature. In certain embodiments described elsewhere herein, the first temperature is in the range of 200° C. to 400° C. For example, in certain embodiments, the first temperature is in the range of 250° C. to 350° C., or in the range of 260° C. to 340° C., or in the range of 270° C. to 330° C., or in the range of 280° C. to 320° C., or in the range of 290° C. to 310° C. In certain embodiments, the first temperature is about 300° C. The reduction of the first catalytic material to the reduced catalytic material occurs at a first pressure. In certain embodiments described elsewhere herein, the first pressure is in the range of 0.5 bara to 5 bara, e.g., 0.7 bara to 3 bara. The reduction may be carried out under conditions sufficient to provide a desired degree of reduction, as described above, for a period of time (e.g., up to 48 hours, e.g., 2 to 48 hours or 8 to 30 hours).

[0052] As described herein, treatment of the first catalytic material with a first reducing agent produces a reduced catalytic material that includes cobalt as cobalt metal (e.g., in an amount of at least 50%, e.g., at least 75%, or at least 90% of the cobalt, as described above).

[0053] As described herein, catalyst performance is monitored through performance parameters such as COx conversion, C5+ selectivity, CH4 selectivity, and C5+ productivity. These are calculated based on the conversion per pass as well as the total carbon conversion. Conversion is maintained by adjusting the applied temperature (from the steam drum pressure level) and gradually increasing it to maintain the conversion over the life of the catalyst. (Example)

[0054] The following examples illustrate certain embodiments of the disclosed method and various uses thereof. They are provided for illustrative purposes only and should not be construed as limiting the scope of the disclosure. Example 1

[0055] A Fischer-Tropsch reactor was loaded with a catalyst containing 10% Co and 1% Mn on TiO2. The catalyst was dried at 7 barg and 165°C under N2 with a GHSV of 2000 hr-1. The catalyst was then heated to 250°C at 10°C / hr and activated with 50% H2 in N2 at 26 barg with a GHSV of 6700 hr-1 for 24 hours to produce the reduced catalyst.

[0056] The reduced catalyst was then cooled under a mixture of H2(H)2O. and N2 was carried out by heating to a temperature of 130°C in preparation for the start-up procedure. Subsequently, a gaseous reaction mixture containing H2 and CO in a ratio of 1.8:1 mixed with 51% N2 was introduced at a GHSV of 8795 hr-1. The reactor was heated to 150°C at 50°C / hr, then from 150°C to 160°C at 25°C / hr, then from 160°C to 180°C at 5°C / hr, and finally from 180°C to 205°C at 2°C / hr. The pressure was then increased to 30 barg.

[0057] The temperature was then maintained at 205° C. for 200 hours.

[0058] [Table 1]

[0059] The temperature was then increased to 212 °C and the Fischer-Tropsch synthesis was continued for 280 h to increase the conversion to the experimental target.

[0060] [Table 2] Comparative Example 1

[0061] In this comparative example, the catalyst was reduced as in Example 1, but then cooled only to 180° C. A gaseous reaction mixture containing H2 and CO in a ratio of 1.8:1 mixed with 95% N2 was then introduced, since the inclusion of less N2 would result in a dangerous exothermic reaction at this temperature.

[0062] Various exemplary embodiments of the present disclosure include, but are not limited to, the recited embodiments of the claims listed below, which may be combined in any number and in any combination that is not technically or logically inconsistent.

[0063] (Embodiment 1) 1. A method of initiating a Fischer-Tropsch synthesis in a reaction zone having a catalyst disposed therein, the catalyst being in reduced form, the method comprising the steps of: (i) providing a temperature in said reaction zone of no more than 160° C.; and (ii) purging the reaction zone at a temperature of 160° C. or less with a purge gas comprising N2 at a pressure in the range of 2 barg to 15 barg; and (iii) contacting the catalyst in the reaction zone with a gaseous reaction mixture comprising H2 and CO in a ratio in the range of 1:1 to 3:1 at a pressure not exceeding 45 barg and a temperature not exceeding 160°C; and then, while in contact with the gaseous reaction mixture, (iv) heating said reaction zone to a temperature of at least 200° C.; (v) pressurizing the reaction zone to a pressure in the range of from 25 barg to 45 barg. -(Embodiment 2) The process of embodiment 1, wherein the reaction zone in step (i) is at a temperature in the range of 100°C to 140°C.

[0064] (Embodiment 3) Embodiment 3: The method of embodiment 1 or 2, wherein the purge gas comprises at least 80% by volume N2, such as at least 90% by volume N2, or at least 95% by volume N2.

[0065] (Embodiment 4) Embodiment 4: The method of any one of embodiments 1 to 3, wherein the purge gas comprises 5% or less H2.

[0066] (Embodiment 5) Embodiment 5. The process of any of embodiments 1-4, wherein the purge gas contains 1% or less H2, e.g., 0.1% or less H2, or 0.01% or less H2, or is substantially free of H2.

[0067] (Embodiment 6) The process of any of the preceding embodiments, wherein the purging step (ii) is carried out for a period ranging from 0.1 hours to 24 hours.

[0068] (Embodiment 7) 7. The method of any one of the preceding embodiments, wherein H2 and CO are present together in the gaseous reaction mixture in an amount ranging from 10% to 80% by volume (e.g., ranging from 20% to 70% by volume, or ranging from 30% to 70% by volume).

[0069] (Embodiment 8) 8. The method of any one of the preceding embodiments, wherein H2 and CO are present in the gaseous reaction mixture in a H2:CO ratio ranging from 1:1 to 2.5:1, or from 1:1 to 2:1, or from 1.5:1 to 3:1, or from 1.5:1 to 2.5:1, or from 1.5:1 to 2:1, or from 2:1 to 3:1, or from 2:1 to 3:1.

[0070] (Embodiment 9) 9. The method of any one of the preceding claims, wherein H2 and CO are present in the gaseous reaction mixture in a H2:CO ratio ranging from 1.5:1 to 2.5:1.

[0071] (Embodiment 10) 10. The method of any one of the preceding embodiments, wherein the gaseous reaction mixture comprises at least 20% by volume of H2 and CO.

[0072] (Embodiment 11) Embodiment 11: The process of any one of embodiments 1-10, wherein the gaseous reaction mixture comprises at least 30% by volume H2 and CO (e.g., at least 35% by volume, or at least 40% by volume, or at least 45% by volume).

[0073] (Embodiment 12) Embodiment 12. The process of any one of embodiments 1 to 11, wherein the gaseous reaction mixture further comprises an inert species in an amount of up to 80% by volume, e.g., up to 70% by volume, or up to 60% by volume, or up to 50% by volume.

[0074] (Embodiment 13) Embodiment 13. The process of any of embodiments 1-12, wherein the gaseous reaction mixture comprises N2 in an amount ranging from 20% to 80% by volume, e.g., from 20% to 70% by volume, or from 20% to 60% by volume, or from 30% to 80% by volume, or from 30% to 70% by volume, or from 30% to 60% by volume, or from 40% to 80% by volume, or from 40% to 75% by volume, or from 40% to 70% by volume.

[0075] (Embodiment 14) 14. The method of any of the preceding embodiments, wherein the total amount of reactive species (H2, CO, olefins) in the gaseous reaction mixture is at least 20% by volume, e.g., at least 30% by volume, or at least 35% by volume, or at least 40% by volume.

[0076] (Embodiment 15) 15. The method of any one of the preceding embodiments, wherein the combined proportion of H2 and CO does not change by more than 30%, such as by more than 20%, or by more than 10% throughout steps (iii) to (v).

[0077] (Embodiment 16) Embodiment 16. The process of any of embodiments 1-15, wherein step (iii) further comprises removing a recycle stream comprising synthesis gas from the reaction zone, and recycling at least a portion of the recycle stream to the reaction zone.

[0078] (Embodiment 17) Embodiment 17. The process of any of embodiments 1-16, wherein step (iii) is carried out at a pressure in the range of from 5 barg to 20 barg, for example, from 5 barg to 15 barg, or from 5 barg to 12 barg, or from 5 barg to 10 barg, or from 10 barg to 20 barg, or from 10 barg to 15 barg, or from 12 barg to 20 barg, or from 15 barg to 20 barg.

[0079] (Embodiment 18) Embodiment 18. The process of any of embodiments 1-17, wherein the gaseous reaction mixture is contacted at a GHSV in the range of from 2000 hr-1 to 12,000 hr-1, e.g., from 4000 hr-1 to 12,000 hr-1, or from 6000 hr-1 to 12,000 hr-1, or from 8000 hr-1 to 12,000 hr-1, or from 2000 hr-1 to 10,000 hr-1, or from 4000 hr-1 to 10,000 hr-1, or from 6000 hr-1 to 10,000 hr-1, or from 2000 hr-1 to 8,000 hr-1, or from 4000 hr-1 to 8,000 hr-1, or from 2000 hr-1 to 6000 hr-1.

[0080] (Embodiment 19) Embodiment 19: The process of any of embodiments 1-18, wherein the heating in step (iv) is performed under multiple heating rate conditions including: (a) Heating at a rate ranging from 10°C / hour to 60°C / hour to a temperature below 160°C; (b) heating at a rate ranging from 2°C / hour to 30°C / hour to a temperature ranging from 160°C to 180°C; (c) heating at a rate ranging from 0.5°C / hour to 7°C / hour to a temperature ranging from 180°C to 220°C;

[0081] Embodiment 20. The method of any of embodiments 1-19, wherein the heating rate condition (a) comprises heating at a rate in the range of from 10° C. / hr to 45° C. / hr, or from 10° C. / hr to 30° C. / hr, or from 20° C. / hr to 60° C. / hr, or from 20° C. / hr to 45° C. / hr.

[0082] (Embodiment 21) Embodiment 21. The process of any of embodiments 1-20, wherein the heating rate condition (a) comprises heating at a rate in the range of 2° C. / hr to 20° C. / hr, or 2° C. / hr to 15° C. / hr, or 4° C. / hr to 30° C. / hr, or 4° C. / hr to 20° C. / hr, or 4° C. / hr to 15° C. / hr.

[0083] (Embodiment 22) 22. The method of any of the preceding embodiments, wherein the heating rate condition (a) comprises heating at a rate in the range of 0.5° C. / hr to 5° C. / hr, or 0.5° C. / hr to 4° C. / hr, or 1° C. / hr to 7° C. / hr, or 1° C. / hr to 5° C. / hr, or 1° C. / hr to 4° C. / hr, or 2° C. / hr to 7° C. / hr, or 2° C. / hr to 5° C. / hr, or 2° C. / hr to 4° C. / hr.

[0084] (Embodiment 23) The method of any one of embodiments 1 to 22, (vi) conducting a Fischer-Tropsch synthesis at a temperature of at least 200°C and a pressure in the range of 30 to 45 barg; and withdrawing a hydrocarbon product composition from said reaction zone, said hydrocarbon composition comprising one or more of methane, C5+ hydrocarbons, and oxygenates.

[0085] (Embodiment 24) Embodiment 24: The method of embodiment 23, wherein the Fischer-Tropsch synthesis is carried out at a temperature in the range of 200 to 250°C, for example, or 200 to 240°C, or 200 to 230°C, or 200 to 220°C, or 210 to 250°C, or 210 to 240°C, or 210 to 230°C, or 220 to 250°C, or 220 to 240°C, or 230 to 250°C.

[0086] (Embodiment 25) Embodiment 25. The process of embodiment 23 or embodiment 24, wherein the Fischer-Tropsch synthesis is carried out at a pressure in the range of 30 to 45 barg, for example, 30 to 40 barg, or 30 to 35 barg, or 35 to 45 barg, or 35 to 40 barg, or 40 to 45 barg.

[0087] (Embodiment 26)

[0031] Embodiment 25: The method of any one of embodiments 1 to 25, wherein the catalyst comprises cobalt disposed on a support.

[0088] (Embodiment 27) The method of embodiment 26, wherein the support comprises at least one of titanium oxide, zirconium oxide, cerium oxide, aluminum oxide, silicon oxide, and zinc oxide.

[0089] (Embodiment 28) The method of embodiment 27, wherein the support is a titanium oxide support.

[0090] (Embodiment 29) Embodiment 29. The method of any of embodiments 26 to 28, wherein the catalyst comprises 5 to 35 wt. % cobalt, calculated as cobalt(0).

[0091] (Embodiment 30) Embodiment 30. The method of any of embodiments 26-29, wherein the catalyst comprises cobalt in an amount, calculated as cobalt(0), in the range of 7 to 35% by weight, or 10 to 35% by weight, or 5 to 25% by weight, or 7 to 25% by weight, or 10 to 25% by weight, or 5 to 20% by weight, or 7 to 20% by weight, or 10 to 20% by weight.

[0092] (Embodiment 31) Embodiment 31. The method of any of embodiments 26-30, wherein the catalyst comprises 0.1 to 15 wt. % manganese, calculated as manganese(0), e.g., 0.1 to 15 wt. %, e.g., 0.5 to 12 wt. %, or 0.5 to 10 wt. %.

[0093] (Embodiment 32)

[0026] Embodiment 11. The method of any of the preceding embodiments, wherein at least a portion of the hydrocarbon products are removed from the reactor outlet stream, and the gas phase products and a portion of the unreacted synthesis gas are recycled to the reactor inlet.

[0094] The details shown in this specification are presented as examples and for the purpose of illustrative discussion of certain embodiments of the present disclosure only, and are presented to provide what is believed to be the most useful and easily understood explanation of the principles and conceptual aspects of various embodiments of the present disclosure. In this regard, no attempt is made to show details related to the methods of the present disclosure in more detail than is necessary for a basic understanding of the methods described herein, and the explanation given together with the examples will make clear to those skilled in the art how some forms of the methods of the present disclosure can be embodied in practice. Thus, before the disclosed processes and devices are described, it should be understood that the aspects described herein are not limited to specific embodiments, devices, or configurations, and therefore may, of course, vary. It should also be understood that the terms used herein are intended to describe certain aspects only, and are not intended to be limiting unless specifically defined herein.

[0095] As used in the context of describing the methods of the present disclosure (particularly in the context of the embodiments and claims that follow), the terms "a," "an," "the," and similar referents are to be construed to encompass both the singular and the plural, unless otherwise indicated in the specification or clearly contradicted by context.

[0096] All methods described herein can be carried out in any suitable order of steps, unless otherwise indicated herein or clearly contradicted by context. Any and all examples provided herein, or the use of exemplary language (e.g., "etc.") are intended merely to better illuminate the methods of the present disclosure, and do not impose limitations on the scope of the present disclosure. No language in this specification should be construed as indicating any non-claimed element essential to the practice of the methods of the present disclosure.

[0097] Unless the context clearly dictates otherwise, throughout this specification and the claims, words like "comprise," "comprising," and the like are to be construed in an inclusive sense, i.e., "including, but not limited to," and not in an exclusive or exhaustive sense. Words using the singular or plural also include the plural and singular, respectively. Furthermore, the words "herein," "above," and "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application.

[0098] As will be understood by one of ordinary skill in the art, each embodiment disclosed herein can comprise, consist essentially of, or consist of its particular described elements, steps, ingredients, or components. As used herein, the transitional phrases "comprise" or "comprises" mean including, but are not limited to, and allow for the inclusion of unspecified elements, steps, ingredients, or components, even if in large amounts. The transitional phrase "consisting of" excludes any unspecified elements, steps, ingredients, or components. The transitional phrase "consisting essentially of" limits the scope of the embodiment to the specified elements, steps, ingredients, or components, and those that do not materially affect the embodiment.

[0099] All percentages, ratios and proportions herein are by weight unless otherwise specified.

[0100] As known in the art, "barg" means gauge pressure, i.e., pressure above or below atmospheric pressure in bars, while "bara" refers to absolute pressure in bars.

[0101] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible, however, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0102] Grouping of alternative elements or embodiments of the present disclosure should not be interpreted as limiting. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in or deleted from a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to include the modified group and thus fulfill the written description of all Markush groups used in the appended claims.

[0103] Several embodiments of the various aspects of the present disclosure are described herein, including the best mode known to the inventors for carrying out the methods described herein. Of course, variations of these described embodiments will become apparent to those skilled in the art upon reading the foregoing description. Those skilled in the art may use such variations as necessary, and thus the methods of the present disclosure may be carried out in ways other than those specifically described herein. Accordingly, the scope of the present disclosure includes all modifications and equivalents of the subject matter described in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or clearly contradicted by context.

[0104] As used herein, the phrase "at least a portion" is used to mean that at least a partial amount, up to the entire possible amount, is required.

[0105] Finally, it should be understood that the various embodiments herein are illustrative of the methods of the present disclosure. Other modifications that may be employed are within the scope of the present disclosure. Thus, by way of example, and not of limitation, alternative configurations of the methods may be utilized in accordance with the teachings of the present disclosure. Thus, the methods of the present disclosure are not limited to that precisely as shown and described.

Claims

1. 1. A method for initiating a Fischer-Tropsch synthesis in a reaction zone having a catalyst disposed therein, the catalyst being in a reduced form, the method comprising the steps of: (i) providing a temperature in said reaction zone of no more than 160° C.; and (ii) subjecting the reaction zone to N 2 Purging at a pressure in the range of 2 barg to 15 barg with a purge gas containing (iii) treating the catalyst in the reaction zone with H in a ratio ranging from 1:1 to 3:1 at a pressure not exceeding 45 barg and a temperature not exceeding 160°C. 2 and CO; and then, while in contact with the gaseous reaction mixture, (iv) heating said reaction zone to a temperature of at least 200° C.; (v) pressurizing the reaction zone to a pressure in the range of from 25 barg to 45 barg.

2. 2. The process of claim 1, wherein the reaction zone in step (i) is at a temperature in the range of from 100° C. to 140° C.

3. The purge gas contains 5% or less H 2 3. The method of claim 1 or claim 2, comprising:

4. H 2 4. The process of any one of claims 1 to 3, wherein CO and H2O are present together in the gaseous reaction mixture in an amount in the range of 10% to 80% by volume (e.g. in the range of 20% to 70% by volume, or in the range of 30% to 70% by volume).

5. H 2 and CO in the range of 1:1 to 2.5:1, or 1:1 to 2:1, or 1.5:1 to 3:1, or 1.5:1 to 2.5:1, or 1.5:1 to 2:1, or 2:1 to 3:1, or 2:1 to 3:1 2 5. The process according to claim 1, wherein the H 2 O 2 is present in the gaseous reaction mixture in a ratio of 0.1:1 to 0.2:

1.

6. The reactant species (H 2 6. The process according to claim 1 , wherein the total amount of the reactants (CO, CO, olefins) is at least 20% by volume, such as at least 30% by volume, or at least 35% by volume, or at least 40% by volume.

7. 7. The process of any one of claims 1 to 6, wherein step (iii) further comprises removing a recycle stream comprising synthesis gas from said reaction zone; and recycling at least a portion of said recycle stream to said reaction zone.

8. The heating in step (iv) (a) Heating at a rate ranging from 10°C / hour to 60°C / hour to a temperature below 160°C; (b) heating at a rate ranging from 2°C / hr to 30°C / hr to a temperature ranging from 160°C to 180°C; A method according to any one of claims 1 to 7, comprising (c) heating at a rate in the range of 0.5°C / hr to 7°C / hr to a temperature in the range of 180°C to 220°C.

9. After steps (iv) and (v), (vi) carrying out a Fischer-Tropsch synthesis at a temperature of at least 200°C and a pressure in the range of from 30 to 45 barg; and withdrawing a hydrocarbon product composition from the reaction zone, said hydrocarbon composition comprising one or more of methane, C5+ hydrocarbons, and oxygenates.

10. 10. The method of any one of claims 1 to 9, wherein the catalyst comprises cobalt disposed on a support.

11. 11. The method of claim 10, wherein the support comprises at least one of titanium oxide, zirconium oxide, cerium oxide, aluminum oxide, silicon oxide, and zinc oxide.

12. The method according to claim 11, wherein the support is a titanium oxide support.

13. 13. The process according to any one of claims 10 to 12, wherein the catalyst comprises 5 to 35% by weight of cobalt, calculated as cobalt(0).

14. 14. The method of any one of claims 10 to 13, wherein the catalyst comprises 0.1 to 15 wt.% manganese, calculated as manganese(0), such as 0.1 to 15 wt.%, for example 0.5 to 12 wt.%, or 0.5 to 10 wt.%.

15. 15. The process of any one of claims 1 to 14, wherein at least a portion of the hydrocarbon products are removed from the reactor outlet stream and the gas phase products and a portion of the unreacted synthesis gas are recycled to the reactor inlet.

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