Fischer-Tropsch Catalyst Systems

Abstract

A novel Fischer-Tropsch (FT) catalyst that produces high quality hydrocarbon liquids and waxes even at high reactor temperatures due to improved thermal properties and a highly active surface catalyst coating on the pellets. The catalyst shows a surprising increase in the formation of hydrocarbons and waxes at high temperatures, as well as a specific catalytic activity much higher than previously demonstrated. More generally, catalyst supports, methods for making the catalyst, and FT synthesis methods are described.

Description

[Technical field]

[0001] RELATED APPLICATIONS:This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 294,844, filed December 30, 2021.

[0002] GOVERNMENT RIGHTS: This invention was made with Government support under Contracts DE-SC0015800 and DE-SC0013114 awarded by the U.S. Department of Energy. The U.S. Government has certain rights in this invention. [Background technology]

[0003] Preface Fischer-Tropsch (FT) chemistry emerged in the 1930s to produce synthetic transportation fuels from syngas, primarily derived from coal. Currently, the world is experiencing a need for reduced-carbon fuels, down to zero carbon. Low-carbon syngas or syngas feedstocks for FT, containing carbon monoxide (CO) and hydrogen (H2), can come from renewable non-fossil biomass sources converted by pyrolysis, gasification, or other techniques, from electrolysis-driven conversion of water to reduce hydrogen and / or carbon dioxide to produce CO and oxygen, or from conversion of biogas or natural gas to syngas processes including partial oxidation, steam reforming, or autothermal reforming.

[0004] Fischer-Tropsch is a highly exothermic reaction. Without thermal management, the reaction must be operated at lower temperatures, reducing productivity, to avoid thermal runaway. These compromise conditions are selected to favor the production of desirable liquid hydrocarbons (such as naphtha, diesel, or jet fuel) and waxes, while reducing the production of undesirable by-products of methane, CO2, and light hydrocarbon gases. Advanced reactor designs have been developed to try to address the thermal management issues. These include small microchannel reactors, structured catalysts, and the "CANS" reactor design, which accommodates small conversion steps in stacked radial flow reactors CANS with intervening heat removal between serial flow CANS developed by Davy / Johnson Matthey.

[0005] Large FT reactors are based on slurry or fixed bed reactors that operate with a narrow operating window to control heat and avoid runaway. Slurry bed thermal properties have improved, but they must be constructed on a large scale to achieve useful economics of implementation. The least complex and lowest cost reactor hardware concept is the simple multi-tubular fixed bed reactor. This least complex reactor is limited by heat transfer within the poorly conductive packed bed, which results in low reactor and catalyst productivity. Summary of the Invention

[0006] In a first aspect, the present invention provides a catalyst support comprising three distinct layers (observable by SEM and EDS analysis) and comprising: (1) a core comprising Al, Si, C, and O; a first layer adjacent to said core comprising Al, Si, C, and O; and a second layer adjacent to said first layer, said second layer comprising Al, Si, C, and O, wherein said first layer has a higher porosity than said second layer, and wherein the concentration of O in said core is at least 2.5 wt. % less O than said first layer; or (2) a core comprising Si, C, Al, and O, and at least 2 volume percent of a metallic Al alloy; a first layer adjacent to said core comprising Si, C, Al, and O, said first layer comprising 1 volume percent or less of a metallic phase (preferably an unidentifiable metallic phase); and a second layer adjacent to the first layer comprising Si, C, Al, and O, and comprising 1 volume percent or less of a metallic phase (preferably an unidentifiable metallic phase), said first layer having a higher porosity than said second layer, and said core having a concentration of O at least 2.5 weight percent less than said first layer. These weight ratios of Al, Si, C, and O, including the presence or absence of a metallic phase, can be ascertained from SEM / EDS.

[0007] The present invention, in any of its aspects, may be further characterized by one or any combination of the following features: the core and each layer comprises 10-50 wt% each of Al, Si, C, and O; the core comprises 32-41 wt% Al, 30-39 wt% Si, 3-13 wt% C, and 24-34 wt% O; the first layer comprises 26-34 wt% Al, 25-33 wt% Si, 3-13 wt% C, and 37-45 wt% O; the second layer comprises 25-36 wt% Al, 25-34 wt% Si, 3-13 wt% C, and 37-45 wt% O; and 36-44 wt.% O; defined according to these ratios (core:first layer:second layer), or said first layer comprises 28-32 wt.% Al, 27-31 wt.% Si, 3-13 wt.% C, and 39-43 wt.% O; said second layer comprises 27-34 wt.% Al, 27-32 wt.% Si, 3-13 wt.% C, and 38-42 wt.% O, or alternatively defined according to these ranges, wherein the core is 32.4% Al, ∼30.6% Si, ∼11.3% C, and ∼25.7% O; the core first layer is 27.0% Al, ∼26.2% Si, ∼9.7% C, and ∼37.1% O; the core second layer is 27.5% Al, ∼26.7% Si, ∼9.9% C, and ∼36.0% O; the catalyst support further comprises an outer protective layer of Al and O disposed outside the second layer; the protective alumina layer is at least 20% more porous than the second layer of the core; the Fischer-Tropsch enzyme is disposed on a layer comprising a support (as described herein) and Co metal particles dispersed on an oxide powder which is deposited on the outer protective layer of Al and O (this structure is obtained by depositing a Co catalyst layer on the outer protective layer with a slurry); the first layer is 100-1000 micrometers (μm) thick, or 250-750 μm thick; the second layer is 500-2000 μm thick, or 1000-1500 μm thick, and the protective layer is 25-150 μm thick. the catalyst layer is about 5-200 μm thick, or about 10-100 μm thick; the exterior of the support may be spray coated with an outer layer of aluminum which is then oxidized to produce an alumina layer; the core, the first layer, and the second layer each comprise SiC and Al2O3; and the catalyst support is characterized by an expansion during heat treatment of 1.0% or less (or 0.50% or less, or 0.25% or less) when measured according to conditions corresponding to the data in Table 1.6.2.

[0008] The support and / or catalyst may be further defined by any of the descriptions provided herein, such as composition and / or physical properties. For example, the support or catalyst may be characterized by any of the properties described herein, or may be defined as within ±30%, ±20%, or ±10% of any of the properties described herein (including any properties measurable from SEM micrographs), which may include the measurement conditions described herein. The present invention also includes systems comprising the support or catalyst, including any selected reaction conditions, such as equipment and / or reactants, temperature, and / or pressure, which may be further defined as ±30% or ±20% or ±10% of any condition. For example, the catalyst support may be characterized by having ±20% of one or any combination of pore properties listed from Case 2 of Table 1.6.3.

[0009] In another aspect, the present invention provides a method of conducting a Fischer-Tropsch reaction comprising passing a gaseous mixture of CO and H2 through a thermally conductive pellet catalyst at a temperature of at least 200°C, the thermally conductive catalyst comprising Co metal disposed on an exterior of a catalyst pellet comprising a core comprising Al, Si, C, and O having a first porosity and an outer protective alloy-derived coating layer surrounding and adjacent to the core; wherein the alloy-derived coating has a higher porosity than the core, and the alloy-derived coating is disposed between the core and the Co metal.

[0010] The present invention, in any of its aspects, may further be characterized by one or any combination of the following features: wherein the thermally conductive catalyst comprises a packed bed of pellets disposed in a reactor having an internal diameter of at least 0.7 cm, preferably at least 5 cm; wherein the Co metal comprises Co and / or Re; wherein the gas mixture moves downwardly relative to gravity through the particle bed; comprises an outer catalyst layer comprising the Co metal in the form of metal particles disposed on a porous alumina layer, the outer catalyst layer having a thickness of between 10 and 200 μm, or between 20 and 50 μm; wherein the core and alloy coating layer define a core pellet, the core pellet having a thermal conductivity of 2 to 50 W / m·K, or between 5 and 20 W / m·K; wherein the reaction temperature is in the range of 210-280°C, or 240-280°C, or 260-280°C; wherein the H2:CO feed ratio is in the range of 1:2-3:1, or 1.6-2.0, and the gas mixture is pretreated to remove sulfur and / or ammonia to 1 ppm or less; the partial pressure of water vapor in the reaction mixture is maintained at 6 barg or less; the pressure in the reactor is in the range of 10-40 barg, or at least 20 barg, the reaction is carried out for 500 hours without regeneration, and the catalyst is regenerated with hydrogen every 1000 hours or 2000 hours or more during the reaction; the reaction is carried out at 240°C or greater, and wax is produced along with other hydrocarbons that are liquid at ambient conditions; and the methane selectivity is 15% or less, or 10% or less.

[0011] In another aspect, the invention provides a pellet comprising a central region furthest from a surface and comprising 10% by weight of the pellet comprising aluminum oxide, aluminum alloy, and SiC, and an outer alumina region comprising 10% by weight of the pellet corresponding to a volume of the pellet furthest from the central region, the outer alumina region comprising aluminum oxide, SiC, and the outer alumina region comprising at least 5% higher oxygen concentration compared to the central region of the pellet. The oxygen concentration is preferably measured by electron dispersive X-ray spectroscopy. The pellet may comprise a catalyst support according to any of the aspects of the invention; or may comprise a catalyst support according to any of the other aspects of the invention but without a distinct layer (e.g., a pellet having a layer defined by a selected distance from a central region, or a continuous or stepwise gradient with a layer defined by a selected distance from a central region). In some embodiments, the central alumina region and the outer alumina region define a portion of the catalyst support and further comprise a catalyst layer disposed on the exterior of the pellet.

[0012] The systems of the invention may include a Fischer-Tropsch catalyst with a feed composition comprising carbon monoxide and hydrogen.The invention includes a Fischer-Tropsch process using the catalysts described herein.

[0013] In a further aspect, the invention is a method of making a catalyst comprising providing a catalyst core of the type described herein and coating said core with a slurry comprising Co and / or Re; an organic binder and a plasticizer. Preferably, the organic binder is selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, starch, gum, polyvinyl butyral, and combinations thereof. Preferably, the plasticizer is selected from the group consisting of glycerol, glycerin, ethylene glycol, polyethylene glycol, and combinations thereof.

[0014] In another aspect, the present invention provides a pellet composition comprising a central region furthest from a surface and including 10 wt. % pellets including aluminum oxide, aluminum alloy, and SiC, and an outer alumina region including 10 wt. % pellets corresponding to a volume of the pellets furthest from the central region, wherein the outer alumina region includes aluminum oxide, SiC, and the outer alumina region includes at least a 5% higher oxygen concentration than the central region.

[0015] Preferably, the central alumina region and the outer alumina region define a portion of the catalyst support and further include a catalyst layer disposed on the outside of the pellet. The pellet composition may include a FT synthesis catalyst coating and is characterized by a methane selectivity of ≦15%, ≦10%, ≦8%, or ≦6% and a conversion of at least 5, or at least 10, or at least 12, or at least 15 g of CO per gram of catalyst per hour, characterized using catalyst pellets packed in a tube with an average pellet diameter of about 3 per inner diameter of the tube and a total of about 1 gram of active catalyst, heated to 240° C. and passing H2 and CO in a 2:1 molar ratio through the catalyst at a ratio set to 60-80% CO conversion as described in the activity test of Example 20. The pellet composition may include a FT synthesis catalyst coating and may be characterized by an α of greater than 0.8, preferably greater than 0.84, more preferably 0.85-0.95; this characterization was performed using catalyst pellets packed into a tube with an average pellet diameter of about 3 per inner diameter of the tube, with a total of about 1 gram of active catalyst, heated to 240° C. and passing H2 and CO in a 2:1 molar ratio through the catalyst, with the ratio set to 60-80% CO conversion, as described in the activity test of Example 20. The pellets may have a hydraulic diameter of about 1-10 mm.

[0016] The present invention also provides a method for producing a 2 g CO cat / h or 5-30g / g cat / h CO conversion; and / or a catalyst or FT process characterized by alpha>0.8 at reaction temperatures above 240° C. In addition to FT reactions, the present invention is also applicable to other hyperthermic reactions including exothermic production of methanol, dimethyl ether, oxidation of ethylene, endothermic steam reforming reactions, dry reforming reactions, etc.

[0017] Inventive concepts include any of the supports, catalysts, intermediates, synthetic methods, FT reactions, and / or methods of carrying out reactions, such as systems, described herein (which may be defined to include combinations of compositions, conditions, and / or apparatus). Various aspects of the present invention are described using the term "comprising; however, in narrower embodiments, the invention may alternatively be described using the term "consisting essentially of" or more narrowly, "consisting of."

[0018] Glossary: "Active catalyst" means a catalyst comprising a metal disposed on / in a high surface area support that is considered part of the active catalyst system and is applied as a thin film coating on a substantially dense thermally conductive pellet. The thickness of the active catalyst ranges from about 2 to 200 microns, with a preferred average thickness of about 10 to 100 microns. For activity calculations based on grams of catalyst, the entire coating, including the metal and high surface area support, excluding the weight of the underlying pellet, is considered the active catalyst.

[0019] A "pellet" is typically defined as a compact of solid particles (metal, ceramic, or organic) produced by a process of granulation and uniaxial or static compression. The shape of the compact may vary widely to meet the needs of the reactor design. The term may also be used for the same compact that has been heat treated to volatilize the organic material and form a bonded structure of the remaining particles. Preferably, the thermal conductivity of the pellet is greater than about 2 W / mK.

[0020] Throughout this specification, Al-Si alloys generally refer to alloys containing at least about 5% Si, typically in the range of about 7 to about 15% Si, and preferably in the range of 10 to 14% Si. Throughout this specification, "%" in relation to material composition refers to mass % (weight % is the same as mass %) unless otherwise specified. The hydraulic diameter is defined as four times the cross-sectional area divided by the perimeter. [Brief description of the drawings]

[0021] [Figure 1] SEM / EDS images of Case 1 sample heat treated to 1400 °C; (top left) full pellet cross-section SEM; (bottom left) core region A - coating interface; (bottom right) core region B - coating interface. [Diagram 2] SEM / EDS images of Case 2 with protective coating fired using the process conditions described: (top left) full pellet cross-section SEM; (top right) cross-section SEM of center of pellet (region 1); (bottom left) cross-section SEM of mid-section of pellet (region 2); (bottom right) region 3 of core-coating interface. [Diagram 3] Composition of O, Al, and Si at the pellet exterior, midpoint, and center. [Figure 4] Changes in pellets due to the two synthesis methods (cases 1 and 2). [Diagram 5] Description of the process for making FT coated catalysts. [Figure 6] Pellets packed in a tubular quartz reactor. [Figure 7] A step-by-step description of the steps to activate a catalyst and prepare it for operation. [Figure 8] Comparison of catalytic performance of powdered Co / Re / Al2O3 and Co / Re / Al2O3 coated pellet catalyst (conditions: T = 195 °C, P = 20 barg, H2:CO = 2:1, total flow rate is 30 cm3 min-1). [Figure 9]CO conversion and product selectivity as a function of temperature for Co / Re / Al2O3 coated pellet (left) and powdered Co / Re / Al2O3 (right) catalysts. Operating conditions: P=20barg, H2:CO=2:1. [Figure 10] Effect of H2 / CO ratio on catalytic performance for Co / Re / Al2O3 coated pellet catalyst. Operating conditions: T=225℃, P=20barg. [Figure 11] Selectivity / CO conversion vs. temperature for Co / Re / Al2O3 coated pellet catalyst. Operating conditions: P=20barg, H2:CO=1.8:1. [Figure 12] Selectivity / CO conversion vs. temperature for Co / Re / Al2O3 coated pellet catalyst. Operating conditions: P=20barg, H2 / CO=1.6-1.65:1. [Figure 13] Selectivity / CO conversion vs. H2 / CO ratio over Co / Re / Al2O3 coated pellet catalyst. Operating conditions: T=255°C, P=20barg. [Figure 14] Carbon number distributions recovered by high temperature distillation of exemplary catalyst pellets operated at 240–255 °C with alpha insertion values ​​of H2 / CO feed ratios of 1–1.8 for the three test conditions. [Figure 15] Catalytic performance of Co / Re / Al2O3 coated pellet catalyst at flow times of 259 and 665 hours. Reaction conditions: T=225°C, P=20barg, H2 / CO=2:1, flow rate=30ml / min. [Figure 16] XRD analysis of spent powder and pellet FT catalyst. [Figure 17] Raman analysis of fresh and spent powder and pellet FT catalysts tested in the previous examples. [Figure 18] a) SEM of unused Co / Re / Al2O3 coated pellet catalyst and b) SEM of spent pellet catalyst. There is no obvious peeling or delamination of the FT catalyst coating layer. [Figure 19]Graph of the transient temperature rise in a catalyst pellet with an average catalyst thickness of about 20 μm under FT conditions with a catalyst productivity of 19.7 g CO conversion per gcat catalyst per hour. [Figure 20] Graph of the transient temperature rise within a porous interfacial layer (porosity 0.4) compared to a denser interfacial or intermediate layer (porosity equal to 0.1) for the basic case with an average catalyst thickness of about 50 μm. [Figure 21] Graph of transient temperature rise in a spherical pellet of 300 μm diameter with estimated internal porosity equal to 0.35 using alumina-based pellets with high catalyst productivity of 19.7 g / g / h (solid line) compared to a low catalyst productivity of 2 g / g / h (dashed line). [Figure 22] SEM of catalyst coated pellets using Method #1 (A) and Method #2 (B). [Diagram 23] Product selectivity data (paraffins not including CH4) and total alpha values ​​(C2-C12) for catalyst coated pellets obtained from Method #1 (A) and Method #2 (B), respectively. Test conditions: Flow rates: 10 sccm / min H2 and 5 sccm / min CO, 20 barg. [Figure 24] FT synthesis liquid volume fraction based on an exemplary FT synthesis product composition with alpha=0.8 versus pressure in barg for temperatures between 215° C. and 240° C. [Diagram 25] 1 shows the volume fraction of FT synthesis liquid based on an exemplary FT synthesis product composition with alpha=0.825 versus pressure in barg for temperatures between 215° C. and 255° C. [Figure 26] 1 shows the volume fraction of FT synthesis liquid based on an exemplary FT synthesis product composition with alpha=0.85 versus pressure in barg for temperatures between 215° C. and 265° C. [Figure 27] FT synthesis liquid volume fraction based on an exemplary FT synthesis product composition at 215° C. versus pressure in barg for alphas between 0.8 and 0.85. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The pellet catalyst structure of the present invention comprises a highly thermally conductive, substantially dense core (less than 35% porous) overcoated with a thin layer of active catalyst and with an intervening thin interfacial or protective layer having higher porosity than the core, but which is substantially impermeable. The core comprises SiC and aluminum oxide. The interfacial (or protective) layer is composed of aluminum oxide. By "substantially impermeable" we mean that when the core comprises metallic Al and SiC, the amount of metallic Al and SiC in the core changes by less than 1% when heat treated at 1400°C in air for 3 hours. When packed into a tubular reactor or other configuration, this catalyst structure allows for a higher effective bed thermal conductivity than conventional catalyst pellets, thereby improving the thermal control of the reactor.

[0023] The technology of the present invention has multiple applications for producing synthetic fuels and waxes, including use in combination with electrolysis technologies to produce syngas from CO2 and water to produce fuels and materials with low to negative carbon intensity compared to fossil-derived feedstocks. Carbon dioxide can be captured from atmospheric gases using technologies such as amine scrubbers, direct air capture (DAC), membranes, etc. Alternatively, CO2 can be captured from other industrial processes such as bio-based production of ethanol, which releases nearly half of the incoming carbon as CO2. In this case, CO2 naturally concentrates above atmospheric pressure, reducing collection costs associated with DAC or similar technologies. Syngas should be substantially clean or contain trace amounts (approximately <1 ppm) of sulfur, halide and / or nitrogen-based contaminants. Process unit operations may be required to clean up the syngas or to provide gas prior to forming the syngas. FT catalysts, especially cobalt-based active materials, are particularly susceptible to these poisons, and clean CO2 feedstocks by-produced during fermentation to produce ethanol or other carbonaceous products are particularly advantageous to produce CO in combination with SOEC electrolysis and hydrogen using the FT catalysts of the invention.

[0024] Alternatively, the syngas source may come from biogas or flare gas, which contains both CO2 and CH4. Biogas is produced as a by-product of anaerobic digestion and is used, for example, for wastewater purification, reduction of animal waste, including cattle, pigs, etc., or for conversion of waste food or biomass. In one embodiment, CO2 is partially converted to CO, when limited by reaction rates and thermodynamics, using electrolysis techniques or thermochemical reactors such as reverse water gas shift (RWGS), and then the syngas is converted to hydrocarbon liquids and waxes with the FT catalyst of the present invention. In one embodiment, the methane fraction of the biogas is converted to syngas using partial oxidation with CO2, steam reforming, autothermal reforming, or dry reforming (DRM).

[0025] In an alternative embodiment, natural gas may be used as a feedstock to produce synthesis gas for conversion over the FT catalyst of the present invention. The gas mixture is preferably maintained at a partial pressure of steam less than about 6 barg to reduce the deactivation rate of the FT catalyst. Steam may be present in the feed mixture and co-produced with hydrocarbons during the FT reaction due to the stoichiometry of the reaction. In one embodiment, an advantageous process may include a DRM process that produces synthesis gas operated at a steam to carbon ratio of less than 3, more preferably less than 2 or 1.5 or 1.2, to minimize residual steam in the synthesis gas mixture and / or promote the conversion of CO2 to synthesis gas. The DRM may operate at a higher pressure than the FT reactor and may provide an FT feed synthesis gas with an intervening heat exchanger to reduce the temperature from the higher temperature DRM to the lower temperature FT reaction. In one embodiment, the synthesis gas production reactor operates at a pressure of about 10.5 to 22 barg and the FT reactor operates at a pressure of about 10 to about 21 barg. Intermediate heat exchange and gas separation may be included.

[0026] The present invention includes, but is not limited to, FT processes in which the FT synthesis inlet stream comprises a syngas blend obtained by electrolysis of water and CO obtained by a reverse water-gas shift reaction of hydrogen and CO; or the FT synthesis inlet stream is a syngas blend obtained by electrolysis of water and CO; or the FT synthesis inlet stream is syngas derived from upgrading and reforming of biomethane from an anaerobic digester, landfill, or wastewater treatment facility; or the FT synthesis inlet stream is electrolysis or a reverse water-gas shift reaction that previously sequestered CO from fossil fuel combustion, biological fermentation processes, or direct air capture processes.

[0027] Catalyst support (core) is 0.09~0.17 or 0.10~0.15 or 0.12~0.14m 2 The catalyst support may have, but is not limited to, a BJH adsorption pore area and / or a BJH desorption pore area of ​​0.1 to 0.3, or 0.15 to 0.25, or 0.17 to 0.23 m / g. In some preferred embodiments, the catalyst support has a BJH adsorption pore area of ​​0.1 to 0.3, or 0.15 to 0.25, or 0.17 to 0.23 m / g. 2 The thermal conductivity of the core is preferably in the range of 8 to 20 W / m·K, or 9 to 17 W / m·K at 400° C., as measured using ASTM E1461.

[0028] The present invention is not limited to the amounts of coarse and fine SiC fractions used in the examples. The volume percentage of coarse SiC in the mixed SiC powder preferably varies between 50% and 100%, while the volume percentage of fine SiC varies between about 0% and 50%. Preferably, the coarse SiC may be selected from SiC having a grit size of 230 (average diameter about 70 μm) to 600 (average diameter about 30 μm), while the fine SiC may be selected from SiC having a grit size of 600 (average diameter about 30 μm) to 1200 (average diameter about 15 μm).

[0029] For Al-Si alloy powders, eutectic alloys (11-13% Si) may be used in a variety of particle sizes, e.g., median particle sizes of 2-50 μm. Specific examples include S-2, S-5, S-8, S-10, S-15, S-20, and S-25 grades of Valimet, Inc.'s Al-Si eutectic alloy 4047 powder. Other Al-Si alloys, such as those having up to about 25% Si (on a molar basis), may be used. The volume of Al-Si (or Al, if no alloy is used) in the mixture may vary between about 2.5% and about 80% of the volume of SiC, about 5% and about 50% of the volume of SiC, about 5% and about 30% of the volume of SiC, about 10% and about 30% of the volume of SiC, or about 10% and about 25% of the volume of SiC. When other oxide-forming metals are used in place of or in addition to Al or Al-Si alloys, a similar total amount of oxide-forming metal in the mixture (e.g., 2.5-80% by volume of SiC, 5-50% by volume of SiC, 5-30% by volume of SiC, 10-30% by volume of SiC, or 10-25% by volume of SiC) is used.

[0030] Preferably, the combined volume of PVB and BBP is between 1% and 15% (based on the total formulation before pellet formation), and the weight percentages of stearic acid and carbon can each vary between about 0% and 15%. The volume ratio of BBP to PVB is preferably between about 0% and 50%. The variations are shown in Table 1, where the amounts of SiC and Al-Si are reported as volume % of the total amount of SiC and Al-Si powder, and the amounts of PVP, BBP, stearic acid, and carbon are also reported as volume % of the SiC and Al-Si powder. [Table 1]

[0031] Another preferred composition is shown in Table 2, where the amounts of SiC, Al2O3, and Al-Si are reported as volume percent of the total amount of SiC, Al2O3, and Al-Si powders, and the amounts of PVP, BBP, stearic acid, and carbon are similarly reported as volume percent of the SiC and Al-Si powders. In some preferred embodiments, the catalyst support core may be comprised of a green paste containing 20-40% (or 25-40%) Al-Si alloy, 20-40% (or 25-40%) alumina, 20-40% (or 25-40%) SiC, and up to 10% (or 1-8% or 2-6%) inorganic lubricant (preferably graphite), and up to 20% (or 2-15%, or 4-12%) organic additives (not including liquid solvents). In some preferred embodiments, the powder precursors, including Al-Si alloys, alumina, and SiC, have mesh sizes in the range of about 35-200 (or about 75-600 μm in diameter), selected with at least 80% by weight of the powder precursors within this size range. [Table 2]

[0032] A catalytic core comprising SiC and Al2O3 may be coated with one or more of these interfacial (or "protective" layers) to further protect the SiC component from oxidation when exposed to an oxidizing environment at high temperatures. Under such conditions, a slow-growing silica scale develops on unprotected SiC, which creates a barrier to further oxygen diffusion into the granules, thus preventing further erosion of the substrate. However, the main drawback of the resulting silica scale is its volatility (e.g., formation of Si(OH)4) and susceptibility to corrosion in the presence of alkaline salts (e.g., formation of Na2SiO4), limiting its applicability. To mitigate this, an outer "interfacial" or "protective" coating acts as a barrier between the atmosphere and the SiC surface. Each of the one or more interfacial layers comprises alumina, silica, titania, zirconia, or a mixture or oxide compound of two or more of the foregoing (e.g., mullite). As another example, an outer protective layer of aluminum, or an aluminum alloy containing a metal mixture with other transition metals or metal oxides, may be applied as a thin coating on the surface of the support material to form an interfacial layer that is converted to a substantially dense oxide layer upon firing.

[0033] One example of this approach is a thin coating of aluminum applied to the core surface. The coating can be applied by a number of methods, including but not limited to dip coating, spray coating, spin coating, or vacuum infiltration.

[0034] A protective (or interfacial) alumina coating may be obtained from an Al-Si alloy powder that is deposited onto the SiC / Al composite cores using aerosol deposition, preferably at ambient temperature and pressure. For example, the core pellets may be kneaded in an oval "panning" vessel to create a cascading action. Alternatively, the coating may be performed on the pellets on a moving conveyor or in a fluidized bed to achieve a similar coating effect.

[0035] An outer, "interface", or "protective" coating may be applied to a pre-fired support material or to the as-formed core shape as disclosed below. Following firing, any metal (e.g., aluminum) in the coating is substantially converted to an oxide. Preferably, the thickness of the protective oxide layer is in the range of 1-200 mm, more preferably between about 10-100 μm.

[0036] The porosity of the protective or interface layer is greater than the porosity of the pellet core. The protective layer inhibits gas flow or diffusion into the interior of the pellet. The porosity of the core is preferably in the range of about 1-35% by volume, or 10-30% by volume, or about 12-20% by volume, while the porosity of the protective layer is less than 40% by volume, more preferably less than 30% by volume, and in some embodiments this is in the range of about 0.1% to 30%.

[0037] The "interfacial" coating slurries used may vary from organic solvent and binder systems to aqueous solvent systems with polymeric binders, or combinations thereof. The coating materials may vary from pure alumina materials to alumina mixed with other metals, metal oxides, or nonmetals. The size of the core and the thickness of the interfacial layer are larger in the green state before heat treatment; for example, the thickness may shrink by 3-7 times, or 4-6 times.

[0038] In some preferred embodiments, the green substrate is heat treated in an air-containing atmosphere to a temperature of about 1300-1500° C., or 1350-1450° C., or 1380-1420° C., preferably at a rate of 1-10° C. per minute, or up to 5° C. per minute, and preferably held at this temperature for at least 1 hour, or at least 2 hours, or 1-5 hours, or 2 hours to 4 hours.

[0039] The coated pellets are preferably dried and calcined at a temperature in the range of about 800-1500° C., preferably about 1000-1450° C., even more preferably 1250-1400° C. During calcination, the gas atmosphere is usually static air. EXAMPLES

[0040] Example 1.1 - Description of pellet preparation (Case 1) formulation: 652.6 g of 400 grit SiC (average diameter approximately 40 μm), 163.2 g of 1200 grit SiC (average diameter approximately 15 μm), and 169 g of Al-Si alloy powder (Valimet eutectic alloy 4047 (11-13% Si) (Grade S-2, average diameter 2 μm)) are combined and transferred to a powder mixer where they are thoroughly mixed. The weight and volume percentages of each of the mixtures are recorded in Table 1.1.1. [Table 3]

[0041] Granulation: Separately, 3.5 g of PVB is dissolved in 50 g of ethanol by stirring and warming. The ethanol solution of PVB is then sprayed onto the powder with continuous mixing. The evenly wet powder is then spread in a shallow layer and dried at 120°C until completely dry. The dry powder is sieved to 35-200 mesh after drying. 4% by weight of stearic acid and 4% by weight of graphitic carbon (KS-6) are added to this powder as powders and homogenized. Sufficient ethanol is then sprayed onto the stirred powder to wet the mixture. The mixture is again dried and sieved to 35-200 mesh before pressing.

[0042] Pelletization: The dry powder blend is dry pressed into pellets using a laboratory scale press. Pressing can be performed in either a manual or automated pellet press, and pressure can be applied uniaxially or statically.

[0043] Example 1.2 - Coated Press Pellets (Case 1) In this example, an organic-based coating system is used. The composition of the coating slurry for the interface or protective layer coating is disclosed in Table 1.2.1. Examples of a range of successful coating formulations are listed but should not be considered limiting with respect to potential coating systems.

[0044] The slurry is deposited onto either the pre-calcined or non-pre-calcined material cores of the present disclosure. In this embodiment, the coating is deposited onto the cores by an organic-based aerosol spray approach, both manually and alternatively using an automated spray device. In either approach, depending on the desired thickness of the final coating, the spraying is performed either in one step or through several repeated coatings with intermediate drying cycles. The drying cycles may be performed in air at a variety of temperatures from about 60° C. to 150° C. [Table 4]

[0045] Example 1.3: Heat treatment (case 1) Once dried, the coated pellets are fired in air at temperatures ranging from about 800-1500°C, but preferably from about 1000-1450°C, and even more preferably from 1250-1400°C. The firing profile included two intermediate dwell times at 400 and 600°C. The overall firing profile was as follows: ramp 3°C / min to 400°C, then dwell 1 hour at 400°C, then ramp 2°C / min to 600°C, then 2 hours at 600°C, then ramp 2°C / min to the final temperature and dwell 1 hour. An example of the resulting microstructure is shown in the micrograph in Figure 1.

[0046] Example 1.4 (Case 2) formulation: To prepare the catalyst support core, powders of Al-Si alloy (S-2, Valimet), aluminum oxide (A-1000 SG Almatis), and SiC powder (400 grit, Panadyne) were first blended in an Eirich mixer EL10 (Model No. RV02E). The specific amounts are shown in Table 1.4.1. [Table 5]

[0047] Granulation: To make the material acceptable for dry pressing, binders and lubricants are added in such a manner that the powders are homogenized and granulated to allow good flow of the dry materials during operation of the automatic pelletizing press. The powders are weighed out to produce 6000 g batches of inorganic materials in the ratios listed in Table 1.4.1 and homogenized in the bowl of an Eirich mixer. The powders are stirred for 120 seconds at an arm speed of 10 meters per second while the bowl is rotated in a slow counterclockwise direction. The stirring is adjusted to 18 meters per second and 425 g of an ethanol solution (92.9 wt%) of polyvinyl butyral (6.6 wt%) and butylbenzene phthalate (0.5 wt%) is gradually added to the mixture at 5 minute intervals. Once the entire solution has been added, the arm speed is increased for 5 minutes and the ethanol solvent is allowed to evaporate. Two additional binder deposition-drying cycles are run to complete the binder addition. The resulting clay-like bodies are passed through a #14 mesh, divided into stainless steel pans, and dried in a forced air oven for 25 minutes at 60° C. The dried material is removed from the pan and sieved through −35 / +200 mesh to separate the +35 and −200 mesh fractions for recycling.

[0048] The sieved powder is then returned to the Eirich mixer and 4% of the sieved powder weight of stearic acid powder (Alfa Aesar, A17673, 90+%) and 4% of the sieved powder weight of synthetic graphite powder (Timcal, KS-6) are added to the granulation and dry mixed for 5 minutes. Additional binder solution is added to the blended powder to further agglomerate the material and incorporate the lubricant. The binder solution is added in stages with intermediate drying until the entire amount has been added.

[0049] The powder is sieved again through #14 mesh, dried in a 60°C oven for 5 minutes, and then sieved through 35-200 mesh to produce the final product. This material is dried at 60°C for an additional hour.

[0050] In summary, the equation for Case 2, when corrected for the total final material composition after drying, is: 29.96 wt% SiC-400, 29.96 wt% Al2O3, 29.96 wt% Al-Si, 2.59 wt% PVB, 0.19 wt% BBP, 3.65 wt% stearic acid, 3.65 wt% carbon.

[0051] Pelletization: The granulated powder may be pelletized using a range of uniaxial or isotonic presses. As an example, the granulated powder is added to the hopper of an automatic uniaxial pelletizing press (Korsch, model EKO), which produces pellets 6 mm in diameter and approximately 4 mm in height from 0.25 g of powder. The resulting pellets are mechanically robust, shiny, and have a uniform internal structure without significant defects.

[0052] Example 1.5: Al-Si coated pressed pellets (Case 2) To prepare the interface or protective coating suspension, 100 g of Al-Si alloy powder with a D50 of 3.5 μm (Valimet S-2, 11-13% Si) is added to a 1 liter Nalgene container in which a solution of 300 g methyl acetate, 72.5 g alpha terpinol, and 27.5 g screen printing vehicle (Heraeus V006A) is prepared.

[0053] The composition of the coating slurry for the third layer coating is disclosed in Table 1.5.1. A range of examples of successful coating formulations are listed but should not be considered limiting. The slurry is deposited onto either the pre-calcined or non-pre-calcined material cores of the present disclosure. In this example, the coating is deposited onto the cores by an organic-based aerosol spray approach, both manually and alternatively using an automated spray device. In either approach, depending on the required thickness of the final coating, spraying is accomplished either in one step or through several repeated coatings with intermediate drying cycles. Drying cycles may be performed at a variety of temperatures from about 60 to 150°C.

[0054] The Nalgene container is then placed on a rotating rack and ball milled at 25 RPM for 8 hours. After the milling operation, the suspension is decanted from the mill into a reservoir. The suspension is deposited onto the as-compressed SiC / Al pellets using an aerosol nozzle, as described below. [Table 6]

[0055] The pellets (300 g, diameter about 6 mm, height about 4 mm) are loaded into a pellet coater (BYC-600, Jiavansshu) with a 60 cm diameter container and rotated at a rotation speed of 20 RPM for 0.5 h. This operation serves to remove roughness and high radius of curvature features from the pellets. Residues from the polishing process are removed from the chamber prior to coating.

[0056] Coating is performed using a pellet coater (BY-200, Jiawans included) with a 20 cm diameter container rotated at a rotation speed of 20 RPM. Coating is aerosol deposited at 10-15 s intervals, alternating with a stream of warm, dry air at 40-50 s intervals. Between the drying step and the subsequent coating step, the pellets are allowed to equilibrate for 15-20 s. Five repeated cycles of coating-drying-equilibration are performed.

[0057] Additional coat-dry equilibration cycles are performed to achieve a deposition target of about 0.04 g of alloy per gram of pellet, or about 0.01 g per 0.25 gram of pellet.

[0058] Similar microstructures may be achieved by dip or wash coating with aqueous or solvent-based suspensions at ambient pressure or vacuum conditions, and in some cases, a similar coating can be achieved by dry tumbling the core with a mixture of aluminum powder and a suitable binder. The size of the core and the thickness of the interface layer are larger in the green state before heat treatment. The dimensions decrease from about 125-25 μm thick in the installed state to about 100-20 μm thick after firing or heat treatment.

[0059] Example 1.6: Heat treatment of HP3.0 After the target coating weight is applied to the pellets, the pellets are placed in an alumina sagger and heated in air to 1400°C at a rate of approximately 3°C per minute, then held for 3 hours and cooled to room temperature at a rate of approximately 5°C per minute. The fired, coated pellets are blown with compressed air to remove any loose particulates from the coating operation.

[0060] In some preferred embodiments, the green substrate is heat treated by heating to a temperature of about 1300-1500° C., or 1350-1450° C., or 1380-1420° C., preferably at a rate of 1-10° C. per minute, or up to 5° C. per minute, and preferably held at this temperature for at least 1 hour, or at least 2 hours, or in the range of 1-5 hours or 2 hours to 4 hours.

[0061] Micrographs of the resulting pellets were taken. A representative example is shown in Figure 2. In contrast to the microstructure of Figure 1, there are several favorable features of the resulting pellets. Starting from the outside and working inwards, the alumina-containing coating at the surface can be delineated from the underlying core by being much more uniform in composition and microstructure, and lacking Si-containing phases when assessed by EDS. This differs from Figure 1, where there is evidence of significant segregation of Si and formation of Si-containing phases as shown by EDS.

[0062] Additionally, the coating and core of case 2 are less porous than case 1. This is demonstrated by stereological analysis of the microstructure using Image J software (www.imagej.nih.gov) to determine the percentage of pores in the microstructure of different sections of the pellet. It is well established that the area fraction of a phase observed in a 2D image represents the volume fraction of the same phase observed in the 3D structure. Table 1.6.1 captures the percentage of pores measured in the core and protective layer of case 1 and 2 parts fired at 1400°C. The porosity of the protective or interfacial layer is greater than that of the core.

[0063] The microstructure of Case 2 is shown to be substantially impermeable to the subsequent coating slurry that is coated onto the pellets, thereby developing a separate catalytic coating layer.

[0064] The volume percentage of porosity of the core and protective layer is determined by measuring the area fraction of pores within an area of ​​a 2D cross-sectional micrograph. Multiple sample areas (at least five) are used to provide a representative analysis. Similarly, the area fraction of various phases can be determined from Energy Dispersive X-ray Spectroscopy (EDS) images (at least five) of similar 2D sections. [Table 7]

[0065] Comparison of oxygen concentration trends in Example 1.2 (Case 1) and Example 1.4 (Case 2): An important difference between the Case 1 and Case 2 examples is the difference in oxygen content from the exterior to the interior of the pellet. Electron dispersive X-ray spectroscopy was used to measure the concentrations of O, Al, and Si at the surface, interior, and near center of the pellets obtained from the SEM / EDS analysis (as shown, for example, in the color diagrams provided in U.S. Provisional Patent Application No. 63 / 294,844, which is incorporated by reference as if reproduced in full below). These analyses result in the graph of FIG. 3.

[0066] Case 1. In this case, the oxygen, Al, and Si levels show slight variations throughout the thickness of the part. This indicates oxygen pathways for diffusion from the exterior to the innermost core of the pellet during heat treatment, which also leads to a generally consistent microstructure (Figure 1). As a result, the concentrations of Al, Si, and O are relatively similar and consistent throughout the diameter of the pellet.

[0067] Case 2. In this case, the compositional levels of Al, Si, and O are not uniform. The outer and inner layers have insufficient oxygen diffusion paths. As a result, the concentrations of Al, Si, and O are not uniform throughout the pellet layers. a. The outermost, most oxidized layer has an oxygen content consistent with complete oxidation of the alloy. b. The intermediate layer has a similar level of oxidation but tends to exhibit higher porosity and, in some cases, evidence of residual Al-based alloy. c. The innermost center of the pellet has a clearly reduced oxygen content and a significant proportion of Al alloy.

[0068] Thermal sintering and expansion behavior of cores of Examples 1.2 (case 1) and 1.4 (case 2). The thermal sintering and expansion behavior of the uncoated core samples of Examples 1.2 and 1.4 was evaluated by heating the samples to 1400°C at 1°C / min to determine the difference in sintering shrinkage and expansion during heat treatment. As shown in Figure 4, both samples show similar characteristics of sintering, with an initial expansion until melting and rearrangement of the composite binder begins at 210°C. The part shrinks until the part begins to expand in the temperature range of 350-450°C, reaching a level where it gradually expands above 600°C. Upon cooling, the sample shows a nominal linear shrinkage with temperature.

[0069] As shown in Table 1.6.2, the sample in Example 1.2 (Case 1) has more significant overall expansion through thermal cycling and a lower thermal expansion coefficient after reaching the upper set point compared to the sample in Example 1.4 (Case 2). Considering how these cores may interact with the transitioning aluminum to alumina protective coating, it would be preferable to minimize the overall expansion / contraction (Case 2) and have a thermal expansion coefficient closer to alumina (8.5 ppm / °C) to reduce stresses during heating and cooling. These contraction behaviors may contribute to the difference in protective coating density observed between Case 1 and Case 2. [Table 8]

[0070] Surface Area: Brunauer-Emmett-Teller (BET) surface area is measured by the adsorption and desorption of physically sorbed nitrogen molecules from the powder surface. Another parallel technique, the Barrett-Joyner-Halenda (BJH) method, is a procedure for calculating pore size distribution from experimental isotherms using the Kelvin model of pore filling. As observed in the data above, the Case 2 embodiment has a smaller surface area per gram (about half the surface area of ​​Case 1), indicating that the outer protective coating is less susceptible to fluid intrusion, an observation supported by the smaller pore area and volume measured for Case 2 vs. Case 1 (Table 1.6.3). [Table 9]

[0071] Thermal Conductivity: The thermal conductivity of the cores for Case 1 and Case 2 was measured using ASTM E1461 (Standard Test Method for Thermal Diffusivity and Conductivity by Flash Method). Data was collected over the temperature range for Case 1 and Case 2 for uncoated core specimens sintered at 1300°C. As shown in Table 1.6.4, despite the large differences in the compositions of silicon carbide and alumina, as well as the differences in the porosity of the cores, across the entire range of conditions, the composites exhibit relatively favorable high thermal conductivity. [Table 10]

[0072] Example 2. Preparation of catalyst Cobalt-based Fischer-Tropsch catalysts are prepared in powder form for subsequent testing, both in granular form and coated on pellets, as described in Examples 1.4-1.6.

[0073] Materials and Chemicals Alumina support (98% Al2O3, PURALOX® TH 100 / 150 L4) is obtained from Sasol. Co(NO3)2·6H2O (98%) and perylene acid solution (HO4Re, 75-80 wt% in H2O) are purchased from Sigma-Aldrich and used as received. Pellets were prepared using the method described in Example 1.

[0074] Preparation of catalyst The Al2O3 support is pre-calcined at 500 °C in air for 2 h (ramp rate: 5 °C / min) and stored in a desiccator. 46 g of Co(NO3)2-6H2O and 1.1 mL of HO4Re solution are dissolved in 22 mL of H2O as a stock solution. 8 mL of the stock solution is added to 20 g of pre-calcined Al2O3 support via incipient wetness impregnation method, followed by drying at 90 °C for 8 h and calcination at 350 °C for 3 h in air with a ramp rate of 5 °C / min. This procedure is repeated twice by adding 7 mL of the stock solution to the solid mixture until the entire 22 mL of stock solution is used. The process of preparing the catalyst is shown in Figure 5. The weight of the obtained powder catalyst is about 35 g and is called Co / Re / Al2O3 catalyst. The nominal loadings of Co and Re are 30.3 wt% and 4.8 wt%, respectively, in the high surface area alumina support.

[0075] To prepare the catalyst slurry, 3 g of Co / Re / Al2O3 catalyst is ball milled with 17 mL of water for 3 hours. The pellets prepared in Example 1 are dip coated into this catalyst slurry and dried in air at 80°C to obtain a thin, uniform coating. This dip coating process is repeated six times. The coated pellets are calcined at 550°C for 4 hours in air at a ramp rate of 5°C / min. Each pellet has approximately 5.9±1.1 mg of Co / Re / Al2O3. The catalyst preparation steps are shown in Figure 5 with the as-received pellets (top), pellets with a thin Co / Re / Al2O3 coating (1), and pellets with excess slurry coating (2). The pellets with a thin Co / Re / Al2O3 coating were used for further testing as described in Examples 3-13.

[0076] Example 3. Loading of catalyst pellets in the reactor The catalysts were evaluated in the Fischer-Tropsch (FT) reaction using a fixed-bed plug-flow reactor consisting of a quartz tube with an inner diameter of 7 mm. The reactor quartz tube was placed in the center of a stainless steel housing. For powder catalyst testing, the Co / Re / Al2O3 catalyst was first sieved through 60–120 mesh (or diameter of about 125–250 μm) and a total pellet weight of 0.4398 g was packed into the quartz reactor (a 19 mm high fixed bed of catalyst with glass wool holding either side of the granular catalyst). For pellet catalyst testing, 20 pellets with a total weight of 0.1108 g of Co / Re / Al2O3 coated catalyst were packed into the quartz reactor using alternating horizontal and vertical pellet arrangements as seen in Figure 6, with a total packed bed height of about 0.105 m.

[0077] The pellets were held in a substantially horizontal orientation during loading and loaded with extended tweezers. The loaded or filled tube was moved to the vertical orientation desired for reactor operation. The estimated bed void fraction for this loading configuration is 0.56. Each pellet is 3.64 mm high and 6.04 mm in diameter, as measured before catalyst coating. For each pellet as loaded, there is approximately a 0.5 mm gap between the pellet and the inner surface of the reactor tube.

[0078] Example 4. Activation of the catalyst before operation Activation of both powder and pellet catalysts was carried out in a tube furnace, involving two redox cycles, each consisting of two steps: 1) reduction of the catalyst with 10% H in N at 1 bar (50 cm 3 minutes -1 The gas was then ramped from room temperature to 250°C at a rate of 0.5°C / min, held at 250°C for 30 minutes, then ramped to 400°C at a rate of 0.5°C / min, held at 400°C for 10 hours, and then nitrogen (50 cm 3 minutes -1) and cooling to room temperature; 2) oxidation of the catalyst at 1 bar (50 cm 3 min-1), ramp from room temperature to 350 °C at a rate of 2 °C / min using 1% O in N and hold at 350 °C for 2 h, followed by a flow of N (350 °C, 50 cm 3 After completing two redox cycles by repeating the above two steps, the catalyst is transferred to the isothermal region of the reactor and the final reduction is carried out in situ at 1 bar (25 cm 3 minutes -1 ) at 400°C for 12 hours at a rate of 0.5°C / min using H2.

[0079] The initial catalyst redox activation step is performed in a separate test rig (tube furnace) from the operational reactor test stand. By this method, the exemplary catalyst can be activated separately from the final reactor equipment, except for the final reduction step in hydrogen. The catalyst is reduced in hydrogen prior to operating the FT reaction. The separate redox step of catalyst activation serves to reduce the complexity and cost, while at the same time improving the safety of in situ redox catalyst activation in a Fischer-Tropsch facility. The activation and reduction prior to operation are shown in FIG. 7.

[0080] Example 5. Reactor operation After activating the catalyst as described in Example 4, the reactor temperature was ramped down from 400° C. to 160° C. where the total pressure was increased to 20 barg in 25 sccm H flow and then the gas was switched to a H2 and CO feed mixture with a H2 / CO ratio of 2. A heating rate of 0.1° C. min / min was used to approach the target temperature. It is understood that all reaction pressures reported refer to the measured gauge pressure and are expressed in either bar or barg.

[0081] The catalytic activity and product selectivity were measured using online chromatography-mass spectrometry with two sampling loops (GC-MS, Agilent 7890A-5975) when the system approached steady state after at least 12 hours of TOS. The GC / MS system and the reactor outlet were connected through a capillary tube and maintained at 200 °C with a heating tape to avoid condensation of heavy products. Light gases (up to C3) were measured by a thermal conductivity detector (TCD) with two connected columns, 3 Foot and 9 Foot Hayesep Q 80 / 100 (backflush mode), while C 4+ Hydrocarbons and alcohols were analyzed by MS detector and DB-1 capillary column. The CO conversion was calculated from the sum of all carbon products and carbon balance.

[0082] product analysis C1-C3 were analyzed by a thermal conductivity detector (TCD) with two connected columns, a 3 Foot and a 9 Foot Hayesep Q80 / 100 (backflush mode), while C4-C 13 were analyzed by an MS detector equipped with a DB-1 capillary column. Calibration of the TCD and MS signals to concentration (mol%) was performed using standard calibration gas mixtures.

[0083] C4-C 12 Calculate the alpha number using the mass fraction of C 32 (C by external analysis of the sample) 32 (The presence of hydrocarbons up to HC was confirmed), C1-C 32 Due to limitations of the GC-MS system, the quantitative analysis of paraffins was limited to C1-C 12 The alpha numbers of paraffins can only be accurately determined for the C4-C3 fraction, since the C1-C3 fraction does not follow the Schultz-Flory distribution as expected. 12 In the external analysis of the sample, C 32 Since the presence of HC was confirmed up to C4-C 12 By using the alpha number calculated from 13 -C32 The alpha number was estimated by linear extrapolation up to the Anderson-Schulz-Flory equation.

number

number

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[0084] Example 6. Comparison of powder and pellets at 195°C Both powder catalyst and catalyst coated pellet catalyst were compared at a reaction temperature of 195°C as measured by thermocouples at the end of the catalyst bed. Furthermore, the pressure was kept constant at 20 barg and data was collected at a time on stream (TOS) of 110 and 131 hours, respectively. The feed gas mixture of H2 and CO with H2 / CO ratio set at 2 was controlled at a total flow rate of 30 ml / min (STP) without any additional diluent. As shown in Figure 8, the pellet catalyst at this temperature showed lower CO conversion (34.30% vs. 57.03%) and relatively higher methane selectivity (18.89% vs. 12.63%) than the powder catalyst. Very little wax was formed in the liquid products, which was further confirmed by the analysis of the two liquid products (high temperature distillation to obtain the carbon distribution of mass fraction by carbon number).

[0085] The pellet catalyst at this low temperature also showed slightly higher selectivity to olefins, alcohols (mainly methanol, ethanol, and 1-propanol), and CO. Nevertheless, the pellet catalyst showed much higher CO conversion than the powder catalyst (i.e., 2.34 vs. 0.97 CO conversion / g at 195 °C). cat / h). The grams of catalyst in this calculation refer to either the total weight of Co / Re / Al2O3 catalyst directly loaded for the granulated powder tests, or the total and a small amount coated for the pellet tests. The data are shown graphically in Figure 8 and in tabular form in Table 6.2. [Table 11]

[0086] Example 7. Effect of Temperature on Powders and Pellets at 20 barg The effect of temperature on the catalytic performance of both powder and pellet was evaluated at 180–220 °C with a feed gas mixture of H2 and CO (H2 / CO ratio of 2). The gas flow rate was adjusted to 30–40 ml / min (STP) for powder catalyst and 15–30 ml / min (STP) for pellet catalyst to control the CO conversion.

[0087] For the powder catalyst, the CO conversion increased from 0.69 to 0.97 g CO / g as the temperature increased from 185 to 195 °C. cat / h. The selectivity to olefins and alcohols decreased, while the CH4 selectivity remained relatively constant at about 12.5%. When the temperature was increased to 200 °C, the powder catalyst achieved nearly 100% CO conversion, or 2.27 g CO conversion / g cat / h CO conversion, while the CH4 selectivity increased continuously from 28.92% at 200 °C for 16 h TOS to 63.07% at 200 °C for 20 h TOS.

[0088] After the temperature was reduced to 195°C after the runaway event, the CO conversion remained at 100% (CO conversion rate of 2.27 g CO_converted / g cat / h) and a high CH4 selectivity of 48.5% were observed. Even when the temperature was further lowered to 190°C, the CH4 selectivity (48.09%) did not decrease, and approximately 100% CO conversion was still obtained (CO conversion rate was 1.70 g CO conversion / g cat / h). The catalyst performance before and after the reaction runaway at 200 °C is significantly different in terms of CO conversion and CH4 selectivity. The catalyst was deactivated after the reaction proceeded. Further characterization of the spent powder catalyst by TEM, XRD, and Raman analysis showed the formation of undesirable Co-aluminate spinel and graphitic carbon deposits on the spent powder catalyst (characterization data are given in Example 13).

[0089] For the coated pellet catalyst, there was no runaway reaction. The CO conversion increased with temperature up to above 220°C, while the CH4 selectivity remained relatively constant. The selectivities to alcohols, olefins, and CO2 decreased with increasing temperature. A high CO conversion of 3.28 g CO per g catalyst per hour at 220°C was reached while maintaining a CH4 selectivity of 18.93%. The data is shown in Figure 9.

[0090] Example 8. Effect of H2 / CO Feed Ratio on Pellet Performance at 20 barg and 225°C The effect of H2 / CO feed ratio on the pellet catalyst was studied at 225°C. As the H2 / CO feed ratio was increased from 1 to 2, CO conversion increased from 46.68% to 67.2%, while CH4 selectivity also increased slightly to about 14%, as expected. Selectivities to paraffins, olefins, and alcohols remained relatively constant over this range of H2 to CO feed ratios. The data are shown graphically in Figure 10 and summarized in Table 8.2. [Table 12]

[0091] Example 9. Effect of Temperature at 1.8 H2 / CO Ratio on 20 barg Pellets To test the exemplary pellet catalyst over a wider temperature range, the performance of the pellet catalyst was studied at 230-250 °C with a H2 / CO feed ratio of 2. The coated pellet catalyst did not experience reaction runaway under any of the conditions. The gas flow rate was varied between 56-140 ml / min (STP) to maintain the CO conversion at approximately 40.8-79%. As the temperature increased from 230 °C to 250 °C, the CO conversion increased from 9.33 to 19.7 CO convert / g. cat / h, while the CH4 selectivity remained below 10%. cat A CH4 selectivity of 7.29% was obtained at a productivity of 1000 g / h (g / g / h). The data are shown in Figure 11.

[0092] Selectivities to alcohols, olefins, and CO2 remained relatively constant. The low CH4 selectivities, less than 7% even at 240°C and 245°C, are consistent with high alpha numbers of 0.84 and 0.82, respectively, based on liquid product analysis performed using high temperature distillation (as seen in Figure 14, white and hatched bars). 32 As much as 1000 g of long chain hydrocarbons were detected in the analysis of the liquid samples, consistent with the significant amounts of wax observed in both samples. A CO conversion / g of 19.7 g at 250° C. and 20 barg was achieved with the exemplary pellet catalyst. catThe high CO conversions at 1000C / h represent more than 20 times the productivity over the corresponding powder catalyst, and do so without reaction runaway.

[0093] Example 10. Effect of temperature on H2 / CO ratio of 1.6 to 1.65 on pellets at 20 barg The pellet catalyst was studied at higher temperatures from 230 to 255°C and at H2 / CO feed ratios near about 1.6 to confirm its applicability for high temperature operation without thermal runaway while controlling CH4 selectivity and producing long chain hydrocarbon products. The gas flow rate was adjusted from 56 to 130 ml / min (STP) to maintain CO conversion at about 39.4 to 80.5%.

[0094] As the temperature increases from 230 to 255 °C, the CO conversion increases from 8.75 to 13.47 g CO converted / g cat / h, while CH4 selectivity remained below 6%. As temperature increased, selectivity to olefins increased slightly and paraffin selectivity decreased slightly. Selectivities to alcohols and CO2 remained relatively constant over this temperature range. The data is shown in Figure 12.

[0095] Example 11. Effect of Feed H2 / CO Ratio on 20 barg Pellets at 255°C The performance of an exemplary pellet catalyst at much lower feed H2 / CO ratios of 1 and 1.25 at 255°C is described. For runs with H2 / CO ratios of 1 and 1.25, respectively, the gas flow rates were controlled at 80 ml / min and 90 ml / min (STP). A higher CO conversion (66.3%) was obtained with H2 / CO of 1.25 compared to H2 / CO equal to 1 (CO conversion of 60%), which corresponds to a slightly higher CO conversion (18.12 vs. 16.41 g CO convert / g). cat / h).

[0096] As seen in FIG. 13, slightly higher CH4 selectivity was obtained at a H2 / CO ratio of 1.25 compared to the selectivity at a feed H2 / CO ratio of 1. Nevertheless, very low CH4 selectivity (<5%) was achieved at 255° C. under both H22 / CO feed ratios, which is consistent with the wax observed in the liquid sample vial (hatched sample shown in FIG. 14). In this case, an alpha number of about 0.81 was calculated based on the analysis of the liquid sample provided by high temperature distillation. This sample was taken from an experiment with a H2 / CO ratio of 1. Additionally, a slightly higher selectivity towards alcohols was observed at the lower H2 / CO ratio of 1.

[0097] There was a system upset that interrupted (stopped) the H2 flow between 554 and 568 hours TOS. During this window, only CO was fed to the reactor. Specifically, the catalyst test was run overnight at 250°C and 20 barg (nominal H2: 90 cm 3 minutes -1 , CO:50cm 3 minutes -1 The pressure in the hydrogen cylinder was reduced to 20 barg and the H2 gas flow rate in the reactor was allowed to go to zero for approximately 12 hours. The problem was identified early the next day and the H2 cylinder was replaced. The catalyst bed was then heated at 250°C and 20 barg for 4 hours with a H2 flow (80 cm3). 3 minutes -1 ), followed by CO at 50 cm while keeping other reaction conditions constant. 3 minutes -1 The catalyst performance before and after the replacement of the H2 cylinder is shown in the table below. As shown in Table 11.2, no significant change in CO conversion or CO conversion rate was observed. [Table 13]

[0098] Example 12. Stability of pellet catalyst To gain insight into the stability of the pellet catalyst, the reaction performance at two times on stream (TOS), namely 259h and 665h, was compared under identical reaction conditions: 225°C, 20 barg, H2 / CO of 2, and total gas flow rate of 30ml / min (STP). This comparison was done after testing the pellet catalyst at temperatures as high as 260°C and at feed H2 / CO ratios as low as 1 from TOS of 259h to TOS of 665h. Moreover, the catalyst did not undergo regeneration, as can be seen in Figure 15. The CO conversion increased from 5.61 to 4.57 g converted / g CO. cat / h (from 82% to 67% CO conversion) with negligible change in product selectivity, including maintaining CH4 selectivity below 10%.

[0099] It is well known that Fischer-Tropsch (FT) catalysts exhibit reduced conversion at TOS due to increased wax or liquid hydrocarbons condensing within the catalyst pores. Typically, the initial reactor operating temperature starts at a low level (e.g., 200-210°C) and the temperature is increased stepwise during operation (e.g., up to 215-225°C) to compensate for slow deactivation and thereby span the period between catalyst regeneration and / or replacement. Conventional FT catalysts have an upper reaction temperature limit due to thermal runaway or excessive methane formation.

[0100] The catalytic performance demonstrated herein suggests that commercial FT systems operated with the catalysts of the present invention may begin operation at higher temperatures (e.g., 210-250°C) for higher productivity and then incrementally increase the temperature to even higher temperatures, such as 10-50°C above the starting temperature, to compensate for wax deactivation without experiencing thermal runaway or excessive methane formation.

[0101] These results suggest that the pellet catalyst is stable at very high temperatures for cobalt-based Fischer-Tropsch catalysts. The stability results are consistent with the characterization data of the spent pellet catalyst using TEM, XRD, and Raman, as described in Example 13. All techniques show no evidence of cobalt (Co) sintering, no Co2AlO4 spinel formation, and significantly less carbon deposition compared to the spent powder catalyst. Separate SEM analysis also shows no flaking or delamination of the catalyst coating on the pellets.

[0102] Example 13. Powder and pellet analysis of fresh and used catalysts TEM characterization of both the unused and used powder and pellet catalysts showed no obvious sintering of Co particles (circles), both of which were less than 20 nm in size. XRD analysis of both the unused and used powder and pellet catalysts is shown in FIG. 16. From the XRD diffraction pattern, the used powder catalyst shows the formation of Co-aluminate spinel, which may lead to the formation of predominant CH4. Compared to the used pellet catalyst, the used powder catalyst has a much stronger graphitic carbon peak, suggesting that coke deposition on the used powder catalyst is more severe compared to the used coated pellets. Raman analysis of both the unused and used powder and pellet catalysts is shown in FIG. 17. Significantly more carbon formation was observed on the used powder catalyst due to thermal runaway events compared to the used pellet catalyst. SEM cross sections of the unused and used FT catalysts are shown in FIG. 18.

[0103] Example 14. Transient thermal response of catalyst pellets The catalyst coated pellets include an intermediate layer with a larger porosity than the pellet core, and exhibit robust performance against transient heat transfer. High catalyst productivity can be achieved without thermal runaway. The lower effective thermal conductivity of the highly porous intermediate layer compared to the core results in larger transient thermal gradients along which heat spreads laterally. In fact, the internal temperature of the pellets rises more uniformly. However, the transient temperature rise remains controlled, and the internal temperature rise in the interfacial layer remains below about 15° C. for about 5 seconds or less, which is sufficient time to transfer heat from the pellets partially to the reactant and product streams, and partially through the array of packed pellets, and through the heat transfer wall.

[0104] As measured in Example 9, g per hour cat The catalyst productivity of 19.7 g CO conversion per m was 4147 kg / m 3 Using a coating catalyst density of about 2675 W / m2 and an average coating thickness measured at about 20 μm, 2 This value is estimated using the heat of reaction of 165 kJ / mol released per mole of CO converted by this highly exothermic reaction. th The unsteady-state heat transfer described by equation 5.62 from the (2002) Physical Review (2002) edition was used for a constant heat flux scenario and is shown below. This equation is valid for Fourier numbers (Fo) < 0.2 and underestimates the temperature rise of the spherical pellet catalyst.

number

[0105] The value of alpha (a) is the thermal diffusivity defined below, where k is the thermal conductivity, ρ is the density, and Cp is the specific heat capacity. The effective layer properties of the interface layer are used in the transient equations to describe the transient temperature changes therein.

number

[0106] For a constant heat flux, the temperature increases faster in the porous interlayer, as can be seen in Table 14.1. [Table 14]

[0107] As seen in FIG. 19, the transient temperature of the pellet increases faster with higher porosity. In the illustrative case of Example 9, which has high catalyst productivity, the temperature increases by about 2.2° C. over one second, while the less porous interfacial layer increases by only about 1.5° C. The higher temperature of the interfacial layer spreads the temperature around the pellet, helping to increase the temperature and reaction rate throughout the catalyst. This temperature increase remains thermally controlled without causing thermal runaway. There is sufficient time for heat to be removed from the system through gas-phase heat transfer to the flowing reactant and product mixtures, and through effective radial conduction through the pellet(s) to the reactor wall, where it is removed from the exothermic reactor system.

[0108] Example 15. Transient thermal response with increasing catalyst thickness The catalysts tested in Examples 6 to 12 have a measured catalyst thickness of about 20 μm. To further increase productivity, a thicker catalyst may be advantageous, but excessive thickness is expected to reduce robustness or cause thermal runaway of the reactor.

[0109] For a comparative catalyst productivity of 19.7 g CO conversion per gram of catalyst per hour, where the average catalyst thickness coated on the porous interfacial layer is estimated to be 50 mm, the predicted transient temperature rise is shown in FIG. 20.

[0110] The exemplary catalyst system having a more porous interfacial layer heats up more quickly and is balanced with external heat removal around the pellet to remove the highly exothermic reaction heat and maintain thermal control.

[0111] Example 16. Transient thermal response of conventional pellets A comparison is made with a conventional pellet catalyst having an average diameter of 300 μm, with active catalyst distributed throughout the pellet, and with the same catalyst productivity measured in Example 9 (19.7 g CO converted per g catalyst per hour), and the predicted transient temperature rise is shown in Figure 21. The results suggest that this pellet is capable of thermal runaway under conditions where the catalyst of the present invention operates productively. 2 g CO converted / g cat The low catalyst productivity in 1000 / h indicates that there may be enough time to remove the heat of reaction in a much less active catalyst pellet FT system. This conventional pellet system with low catalyst productivity is more likely to operate under stable conditions.

[0112] The net result shows that an FT system with a highly active coated catalyst on a highly thermally conductive core can achieve stable levels of catalyst productivity that are unlikely to be achieved with conventional pellets, even when the pellets are small (approximately 150 μm diameter, or greater than 300 μm in diameter, as shown in FIG. 21). Such highly active conventional pellets are unlikely to maintain thermal control at the high productivity rates exhibited by the FTS coated pellet catalyst of the present invention, even when these small particles are placed inside a highly thermally efficient reactor such as a microchannel or similar configuration. At this high productivity, it is the interior of the catalyst particle itself that limits heat transfer. The coated FT catalyst system of the present invention overcomes this heat transfer limitation, operating on a highly thermally conductive core with a preferred catalyst coating range of about 10 to about 100 μm, with a more preferred range of about 20 to about 50 μm coating thickness, and is expected to have a thermal conductivity in the range of 2 to 50 W / m·K, with a more preferred range of 5 to 25 W / m·K.

[0113] Example 17. FT performance comparison with other catalysts The Fischer-Tropsch performance of the coated catalyst described in Example 9 is compared to the performance of other Fischer-Tropsch reactors and catalysts. In Table 17.1, the catalyst of the present invention is compared on a reactor volume basis (m of reactor volume per hour). 3 Hit C 5+The coated pellet catalyst of the present invention has a higher volumetric productivity than the conventional reactor. [Table 15]

[0114] Comparison of the catalysts based on g CO converted per gram of catalyst per hour, as shown in Table 17.2, shows that the FT catalyst of the present invention is significantly superior to the prior art. The catalytic activity per gram of catalyst in this exemplary case is significantly higher than the microchannel FT catalyst. The catalytic productivity of the catalyst of the present invention of 19.7 g / g / h is more than three times higher than the best results published by Inatec (2020) and the highest theoretical case (Daly et al, WO2012 / 107718). [Table 16]

[0115] Each of the prior art catalysts has a different amount of cobalt in the formula, and when normalized per gram of cobalt, the catalysts of the invention are significantly higher. The published catalyst productivities compared to the present invention are shown in Table 17.4. [Table 17]

[0116] Example 18. Improvement of catalyst coating using glycerol and polyvinyl alcohol (PVA) solutions versus pure aqueous solutions To further improve the coating uniformity and catalyst performance for the Fischer-Tropsch reaction, the catalyst coating process was modified. The new method #2 results in improved coating thickness uniformity due to more complete surface coating, fewer areas with coating gaps around the pellet, and improved coating quality. The net result of the second coating method is improved FT synthesis performance, where the produced hydrocarbons, as indicated by the calculated alpha value, are in the range of about 0.88 to 0.94, compared to less than about 0.84 for the coating of method #1 used in the previous example.

[0117] Materials and Chemicals γ-alumina support (98% Al2O3, PURALOX® TH 100 / 150 L4) was obtained from Sasol. Co(NO3)2·6H2O (98%) and perrhenic acid solution (HO4Re, 75-80 wt% in H2O) were purchased from Sigma-Aldrich and used as received. Pellets were the core material as described in Example 1 using the synthesis protocol of Case 2.

[0118] Synthesis of catalyst: 30 wt% Co / 4.5 wt% Re / γ-Al2O3 catalyst was synthesized using incipient wetness impregnation method. The Al2O3 support was pre-calcined at 500 °C for 2 h in air and stored in a desiccator. Then, 46 g of Co(NO3)2-6 H2O and 1.1 mL of HO4Re solution were dissolved in 22 mL of H2O as a stock solution. 8 mL of the stock solution was added to 20 g of pre-calcined Al2O3 support by incipient wetness impregnation method, followed by drying at 90 °C for 8 h and calcination at 350 °C for 3 h in air. The same procedure was repeated twice, adding 7 mL of the stock solution to the solid mixture each time, until all of the stock solution was added. The weight of the obtained powder was about 35 g and was expressed as Co-Re / Al2O3 for further preparation of catalyst. The loading ratios of Co and Re were estimated to be 30.3 wt.% and 4.8 wt.%, respectively.

[0119] Coating method #1: Dip-coating procedure of catalyst slurry onto pellets using aqueous slurry. To prepare the catalyst slurry, 3 g of Co / Re / Al2O3 catalyst was ball milled with 17 mL of water for 3 h. The pellets (usually 5-10 pellets at a time) were then dip-coated into the slurry and dried at 80 °C to create a thin coating. The dip-coating and subsequent drying process was repeated about six times to obtain about 2.5 mg of catalyst coating on each pellet. The pellets were then calcined at 550 °C for 4 h in air at a ramp rate of 5 °C / min.

[0120] Procedure for dip-coating catalyst slurry onto pellets using glycerol and PVA-based slurry Coating Method #2: Catalyst slurry was prepared by ball milling 2.5 g of Co-Re / Al2O3 catalyst with 0.12 g of PVA in 16 mL of 40 wt% glycerol solution for 4 hours. Typically, 100 pellets were dip-coated into the catalyst slurry at 80°C to create a thin coating. The dip-coating and subsequent drying process was repeated about three times to obtain about 2.5 mg of catalyst coating on each pellet. The pellets were then calcined at 550°C for 4 hours in air at a ramp rate of 5°C / min.

[0121] Catalyst Evaluation: The Fischer-Tropsch (FT) reaction was carried out as described in Example 3. The activation of the catalyst involved two redox cycles in a tube furnace, each of which consisted of two steps: in the first step, the catalyst was heated to 1 bar (50 cm 3 minutes -1 The catalyst was reduced with 10% H2 in N2 at 1 bar (50 cm3). The temperature was programmed as follows: from room temperature to 250 °C at 0.5 °C / min, held for 30 min, then increased to 400 °C at 0.5 °C / min and held for 10 h. N2 was then introduced while cooling to room temperature. The second step was reduced with 1 bar (50 cm3). 3 minutes -1The catalyst was oxidized with 1% O in N at 25° C. The reactor was heated at a rate of 2° C. / min to 350° C., which was maintained for 2 hours. The reactor was then cooled to room temperature under flowing N.

[0122] After completing two redox cycles by repeating the above two steps, the catalyst was transferred to the isothermal region of the reactor and the final reduction was carried out in situ at 1 bar (25 cm 3 minutes -1 ) H2 at a rate of 0.5 °C / min up to 400 °C for 12 h. The temperature was then reduced to 160 °C, the total pressure was increased to 20 barg with H2, and switched to a H2 and CO mixture. The synthesis temperature was reached at a heating rate of 0.1 °C min / min. Catalyst activity and product selectivity data were obtained when the system reached steady state using chromatography-mass spectrometry (GC-MS, Agilent 7890A-5975) equipped with two sampling loops, after an initial stabilization phase of more than 100 h, after a change in state took at least 12 h TOS. The GC-MS system and the reactor outlet were connected through a capillary tube and maintained at 200 °C with a heating tape to avoid condensation of heavy products. Light gases (up to C3) were determined by a thermal conductivity detector (TCD) with two connected columns, 3 Foot and 9 Foot Hayesep Q 80 / 100 (backflush mode), while C 4+ Hydrocarbons and alcohols were analyzed by MS detector and DB-1 capillary column. The CO conversion was calculated from the sum of all carbon products and carbon balance as described in Example 5.

[0123] Results and Discussion: The SEM images in Figure 22 showed that Coating Method #2 resulted in a much more uniform coating compared to Coating Method #1, which used an aqueous slurry that led to the formation of "islands" in the coated catalyst layer, shown in brackets in Figure 22(A), and on the uncoated surface of the pellet, shown by the arrows. Cross-sectional SEM images overlaid with EDX elemental mapping showed that the catalyst coating resulting from Method #2 improved coating uniformity with a coating thickness range of about 15-23 μm, narrowed from the thickness range of about 5.6-37 microns for Method #1 shown in Table 18.1. [Table 18]

[0124] As shown in Figure 23, more uniformly coated pellets were obtained by method #2 under similar conditions at temperatures between 180 and 200 °C, compared with C2-C 12 The products had higher overall alpha values. The pellets from Coating Method #1 showed alpha values ​​ranging from 0.65 to 0.83, while the pellets from Coating Method #2 showed alpha values ​​ranging from 0.88 to 0.94. Additionally, the pellets from Method #2 showed a higher C2-C4 ratio compared to their Method #1 counterparts due to suppressed CO2 selectivity (<1.8%) and CH4 selectivity (<14.3%) over the entire temperature range tested. 12 The selectivity of paraffins was much improved. C2-C on pellets in Method #2 12 The selectivities for olefins and alcohols are also generally lower than those on the pellets in Method #1. These results suggest that a more uniformly coated catalyst layer on the pellets provides a better catalyst layer for C2-C3 compared to the non-uniformly coated catalyst layer. 12 Significant improvements in more selective production of paraffins are demonstrated.

[0125] The CO conversion for the test conditions and flow rates after a total of 100 hours of operation, with at least 12 hours of operation at each condition, is shown in Table 18.2. The total amount of catalyst coated was 4.04 cm2, coated onto the pellet cores as described in the previous examples. 3 The reactor volume tested was 108 mg of active material including Co, Re, and support material. [Table 19]

[0126] Example 19. Decreasing the operating pressure of FT synthesis It is generally known that to obtain high quality performance of Fischer-Tropsch catalysts, the operating pressure is required to be at least about 20 barg. It is desirable to operate the FT synthesis reactor at a low pressure to match the SMR or DRM front-end process for synthesis gas production, where the reduction in front-end pressure allows for higher equilibrium conversion. In an ideal process, the pressure is sufficient to operate without intermediate compression between the front-end DRM / SMR and the FT synthesis. Furthermore, it is desirable to operate the FT synthesis in two stages, where water and liquids are condensed between the first and second FT stages. The pressure of the second stage FT synthesis is preferably lower than that of the first stage FT synthesis reactor to avoid an additional boost compressor. In this case, the CH4 and / or CO2 produced in the FT synthesis process are converted to C 5+ The overall carbon efficiency for conversion to hydrocarbons is greater than 60%, more preferably greater than 65%, even more preferably greater than 70%, and may range from about 60% to 90%.

[0127] In conventional FT synthesis fixed bed catalysts, the catalyst has low conductivity and the temperature of the internal catalyst site is up to several tens of degrees Celsius higher than the recorded wall or gas temperature. The highly conductive catalyst of the present invention generates less heat and has a lower catalyst temperature. Due to the reduced local temperature resulting from the FT catalyst of the present invention coated on the highly conductive pellets, the liquid film formed in the catalyst pores is expected to remain stable at lower pressures than would be expected from a conventional catalyst pellet.

[0128] The results of the exemplary catalyst showed a CO conversion of 61.3%, methane selectivity of 10.3%, C2 selectivity of 2.7%, C3 selectivity of 1.4%, and C 5+ The product composition was calculated based on a feed syngas ratio of 2:1 without diluent for a hydrocarbon selectivity of 7.6%. The remaining C 5+ The selectivity was 76.6%, with the remaining carbonaceous species being CO2 or other trace amounts of alcohols and aldehydes. 5+ The fraction of C5-C was calculated using α determined by Anderson-Schulz-Flory (ASF) distribution. 30 The resulting compositions were analyzed using VLE flash calculations to estimate the percentage of liquid remaining as a function of reactor temperature and pressure.

[0129] In Figure 24, a typical alpha for a liquid volume fraction of 0.8 is predicted to be 4 to 20 barg for temperatures of 215 to 240°C. For a catalyst operating at an alpha of 0.8 at 230°C, it is predicted that the catalyst of the present invention can reduce the operating pressure from 20 barg to approximately 16 barg.

[0130] In Figure 25, a typical alpha for a liquid volume fraction of 0.825 is predicted to be 4 to 20 barg for temperatures of 215 to 255°C. For a catalyst of the present invention operating at an alpha of 0.825 at 230°C, it is expected that the operating pressure can be reduced from 20 barg to about 8 barg for the catalyst of the present invention while still obtaining excellent results.

[0131] In Figure 26, a typical alpha of 0.85 in terms of liquid volume fraction is predicted to be 4 to 20 barg for temperatures of 215 to 265°C. For a catalyst of the present invention operating at an alpha of 0.85 at 230°C, it is predicted that the operating pressure can be reduced from 20 barg to approximately 4 barg.

[0132] Figure 27 shows the effect of alpha on the retained liquid fraction at 215°C for pressures (barg) from alpha 0.8 to 0.85. The higher the alpha, the greater the reduction in pressure is expected to be to retain a stable liquid film, as enabled by the catalyst structure of the present invention.

[0133] The results of Example 9 showed that for the reactor operating at a pressure of 20 barg, the experimental alpha levels measured were 0.806 at 255° C., 0.816 at 245° C., and 0.838 at 240° C. Higher alpha values ​​at elevated temperatures suggest that further reduction in pressure may occur, with higher alpha values ​​predicting greater reductions.

[0134] The modified catalyst coating protocol described in Example 18 shows an alpha of up to about 0.94. It is expected that coated FT synthesis catalysts operating at high alpha levels should be able to operate at lower operating pressures. The reduction in operating FT pressure may allow for a DRM and / or SMR once-through process to produce synthesis gas followed by one or two stage FT synthesis in succession. Alternatively, the FT synthesis and / or SMR / DRM process using the catalyst of the present invention may be operated in a recycle mode which may also alternatively include inter-stage separation and heat exchange.

[0135] FT synthesis catalysts made using the Method #2 coating process are expected to function at higher temperatures, around 280°C, due to the higher process alpha. Operating pressures are expected to be as low as 6 barg. Liquid volume fractions of around 1×10 under FT synthesis reaction conditions are expected to be around 1×10 -5 It is further expected that if a sufficient liquid film is maintained on the surface of the catalyst when above 0.15 g / cm 2 , the pressure can be lowered more at low temperatures and operated in a stable manner.

[0136] Example 20. Activity test Performance tests to measure catalyst productivity in g / g / h should be performed using FT synthesis catalysts containing cobalt. The catalyst in pellet form is packed into a tubular reactor and sufficient heat is removed along the length of the reactor, as achieved by either partial boiling of water, where the mass fraction of water undergoing phase change is maintained below about 10% at most, or by convection of hot oil or heat transfer fluid (oil velocity is greater than about 1 m / s). The catalyst pellets are packed well with an average particle size of about 3 per tube diameter. The test tube should accommodate about 1 gram of active catalyst, measured by the cobalt or other metal and the high surface area support material on which the active catalyst is placed. Prior to operation, the catalyst is reduced using multiple alternating reduction and oxidation steps described below.

[0137] Activation of the catalyst was carried out in a tube furnace using two redox cycles, each of which consisted of two steps: the first step was performed with 10% H2 in N2 at 1 bar (0.5 L min per gram of catalyst). -1 The catalyst is reduced at 1 bar (0.5 L min per gram of catalyst). The temperature is programmed as follows: from room temperature to 250 °C at 0.5 °C / min, hold for 30 min, then increase to 400 °C at 0.5 °C / min and hold for 10 h. N2 is introduced during cooling to room temperature. The second step is at 1 bar (0.5 L min per gram of catalyst). -1 The catalyst is oxidized with 1% O in N at 1 bar (0.25 L min per gram of catalyst). The reactor is heated to 350° C. at a rate of 2° C. / min and held for 2 h. The reactor is then cooled to room temperature by flowing N at at least 1 liter per min. After repeating the above two steps to complete two redox cycles, the catalyst is transferred to the isothermal region of the reactor and the final reduction is carried out in situ at 1 bar (0.25 L min per gram of catalyst). -1 ) H2 at a rate of 0.5°C / min up to 400°C for 12 hours.

[0138] After the final reduction step, the temperature is ramped down to 160°C and the total pressure is increased to 20 barg with H2 before replacing with a H2 and CO syngas mixture at a feed ratio of 2:1. The start-up flow rate of syngas should be about 18 L / h per gram of catalyst. The temperature is increased from 160°C to 180°C at a rate of 0.5°C / min and held for 100 hours. The temperature is then increased to 5°C at the same rate and held repeatedly for another 24 hours until the temperature reaches 210°C and the conversion of CO is measured. After start-up, the catalyst performance is slowly increased in an iterative manner. After each change in either flow rate or temperature, the reactor is held for 24 hours to stabilize the performance.

[0139] If the conversion of CO is less than 30%, increase the temperature by 0.5 °C / min in increments of 5 °C and hold for 24 h until the conversion is greater than 30% but not greater than 60%. If the conversion is greater than 30%, the total gas flow rate is doubled, i.e., from 18 to 36 L / h / g. cat Increase the temperature to 5°C at the same rate of 0.5°C / min and hold for 24 hours until the conversion is again above 30% but not above 60%. Continue this cycle with a 20-50% increase in total gas flow rate to at least 300 L / h / gram of catalyst. Increase the temperature to at least 240°C and hold for 24 hours until the conversion is again above 30% but not above 60%. 5+ The catalyst productivity in grams of CO converted is at least greater than 2. Further increases in temperature and gas flow rate are maintained such that the catalyst productivity is about 2-30 g / g / h. If the conversion of CO exceeds 30%, further temperature increases should be limited to about 2° C., followed by a 24 hour hold. The measured methane selectivity is less than about 15%. Catalyst productivity should be measured when the CO conversion is at least about 60% to less than about 80%.

[0140] Liquids are collected when the catalyst is operating at a productivity of at least 2 g / g / h and analyzed using a high temperature distillation column for FTS. The alpha of the liquid hydrocarbons is calculated from the hydrocarbon distribution data described in Example 5, and for high productivity catalysts, the alpha is greater than 0.8 and the methane selectivity is less than 15%.

[0141] References: Altalto Project 2020,https: / / www.velocys.com / projects / altalto / . Cao et al.,2009,Intensified Fischer-Tropsch Synthesis Process with Microchannel Catalytic Rectors,Catalysis Today,140(3-4),149-156. Daly et al.,2012,Fischer-Tropsch Catalysts and Method of Preparation Thereof,WO 2012 / 107718. Daly et al.,2016,US 2016 / 0304789. Desmukh,et al.,2016,Commercializing an Advanced Fischer-Tropsch Synthesis Technology:Advances and Applications,in Fischer-Tropsch Synthesis,Catalysts and Catalysis,361-378. Dittmeyer,R.,Synthetic Fuels from Carbon Dioxide and Renewable Electrical Energy (e-fuels) enabled by Compact Microchannel Reactors,9 th International Freiberg Conference IGCC / XTL Technologies Berlin,June 4-8,2018. Ermolaev,et al.,2013,US 8,525,787. flucrum Bioergy,2020,Sierra Biofuels Plant,https: / / fulcrum-bioenergy.com / facilities / . Glebova,O.,2013,Gas To Liquids:Historical Development and Future Prospects,The Oxford Institute for Energy Studies,https: / / www.oxfordenergy.org / wpcms / wp-content / uploads / 2013 / 12 / NG-802.pdf. Ineratec GMbH,Compact Fischer-Tropsch Synthesis In Gas-To-Liquid Applications,2 nd COMSYN workshoe- Future of BTL products in Europe,Prague and Litvinov,Czech Republic,May 23-23,2019. Ineratec,Power-to-Liquid Pioneer Plant 2022,https: / / ineratec.de / en / power-to-liquid-pioneer-plant-2022 / . LeViness,et al.,2013,Velocys Fischer-Tropsch Synthesis Technology-New Advances on State-of-the-Art,Topics in Catalysis,57(6-9):518-525. Loewert,et al.,2019,Microstructured Fischer-Tropsch Reactor Scale-up and Opportunities for Decentralized Application,Chemical Engineering & Technology,doi:10.1002 / ceat.201900136 Loewert,et al.,2020,Dynamically Operated Fischer-Tropsch Synthesis in PtL-Part 1:System Response on Intermittent Feed,Chem Engineering 4(2),21. Loewert,et al.,2020,Dynamically Operated Fischer-Tropsch Synthesis in PtL-Part 2:Coping with Real PV Profiles,Chem Engineering 4(2),27. Mordkovich,et al.,2012,Support for Catalyst of Exothermic Processes and Catalyst Prepared Theron,US 2012 / 0122674 A1. Oxford Catalysts,2008,https: / / www.velocys.com / arcv / financial / other / re_admission_document_3nov08.pdf Peacock,et al.,2020,Innovation in Fischer-Tropsch:Developing Fundamental Understanding to Support Commercial Opportunities,Topics in Catalysis,63,328-339.

Claims

1. 1. A catalyst support comprising three distinct layers: The catalyst support a core comprising Al, Si, and O; a first layer adjacent to the core, the first layer comprising a first metal oxide; a second layer adjacent to the first layer, the second layer comprising a second metal oxide; wherein the concentration of O in the core is at least 2.5 wt % less O than in the first layer; or a core comprising Si, Al, and O, and comprising at least 2 volume percent of a metallic Al alloy; a first layer adjacent to the core comprising a first metal oxide, the first layer comprising 1% or less by volume of a metallic phase; a second layer adjacent to the first layer comprising a second metal oxide, the second layer comprising 1 vol % or less of a metal phase; the concentration of O in the core is at least 2.5 wt % less O than in the first layer; The catalyst support.

2. 10. The catalyst support of claim 1 further comprising an outer protective layer of Al and O disposed outside said second layer.

3. 3. A Fischer-Tropsch catalyst comprising a support as defined in claim 2, wherein Co metal particles dispersed on an oxide powder are disposed on a layer deposited on the outer protective layer of Al and O.

4. The catalyst described in claim 1, wherein the core further contains C.

5. The core, the first layer, and the second layer are made of SiC and Al, respectively. 2 O 3 The catalyst support of claim 1 comprising:

6. 1. A method for conducting a Fischer-Tropsch reaction, comprising: CO and H 2 passing a gas mixture of The method of claim 1, wherein the thermally conductive catalyst comprises Co metal disposed on the exterior of a catalyst pellet comprising a core comprising Al, Si, and O, and an outer protective alloy-derived coating layer surrounding and adjacent to the core; the alloy-derived coating being disposed between the core and the Co metal.

7. 7. The method of claim 6, wherein the thermally conductive catalyst comprises a bed of pellets disposed in a reactor having an internal diameter of at least 0.7 cm.

8. The method of claim 6 , wherein the core further comprises C.

9. The method described in claim 6, wherein the thermally conductive catalyst further comprises an outer catalyst layer comprising Co metal in the form of metal particles arranged on a porous alumina layer, and the thickness of the outer catalyst layer is 10 to 100 μm.

10. 10. The method of any one of claims 6 to 9, wherein the core and the outer protective alloy-derived coating layer define a core pellet, the core pellet having a thermal conductivity of between 2 and 50 W / m·K.

11. The method according to any one of claims 6 to 9, wherein the temperature is between 210 and 280°C.

12. H 2 10. The method of claim 6, wherein the feed ratio of CO to CO is in the range of 1:2 to 3:

1.

13. 10. The method of any one of claims 6 to 9, wherein the gas mixture is pre-treated to remove sulfur and / or ammonia to 1 ppm or less.

14. A method described in any one of claims 6 to 9, wherein passing the gas mixture through the thermally conductive catalyst is carried out in a reactor, and the pressure in the reactor is in the range of 10 to 40 barg, or at least 20 barg.

15. 10. The method of any one of claims 6 to 9, wherein the reaction is carried out for 500 hours without regeneration; or regenerated every 1000 or 2000 hours.

16. The method of any one of claims 6 to 9, wherein the reaction is carried out at 240°C or above to produce a wax.

17. The process according to any one of claims 6 to 9, wherein the methane selectivity is 15% or less.

18. A pellet comprising a central region furthest from an outer surface of the pellet, comprising Al, occupying 10% by weight of the pellet, and an outer alumina region corresponding to the volume of the pellet furthest from the central region and occupying 10% by weight of the pellet, wherein the outer alumina region comprises Al and O, and the outer alumina region has an oxygen concentration at least 5% higher than that of the central region.

19. 20. The pellet of claim 18, wherein the central region further comprises C and / or Si.

20. Pellets according to claim 18 or 19, having a hydraulic diameter of 1 to 10 mm.

21. 1. A method for producing a catalyst, comprising: Providing a catalytic core according to claim 1; coating the core with a slurry comprising Co or Re; an organic binder, and a plasticizer.

22. 22. The method of claim 21, wherein the organic binder is selected from the group consisting of polyvinyl alcohol, methyl cellulose, ethyl cellulose, starch, gum, polyvinyl butyral, and combinations thereof.

23. 23. The method of claim 21 or 22, wherein the plasticizer is selected from the group consisting of glycerol, glycerin, ethylene glycol, polyethylene glycol, and combinations thereof.

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