Process and apparatus for removing solid catalyst

Abstract

Spent catalyst 500 is removed from the process microchannels 310 of a Fischer-Tropsch reactor by directing air jets 4 from an air knife 1 through slots in a guard member 2. The air knife traverses successive rows of process microchannels 310 in a direction A. The spacer member 2 protects the internal microchannel architecture 315 of the process microchannels against damage from the air jets 4, which may approach or exceed sonic speeds as they are directed into the process microchannels.

Description

[Technical Field]

[0001] The present invention relates to a process for the removal of spent catalyst from a microchannel reactor. The present invention particularly, but not exclusively, relates to a process for the removal of spent Fischer-Tropsch catalyst from the process microchannels of a Fischer-Tropsch reactor. [Background technology]

[0002] The Fischer-Tropsch process is widely used to produce fuel from carbon monoxide and hydrogen and can be represented by the following equation: (2n+1)H2+nCO→C n H 2n+2 +nH2O

[0003] The reaction is highly exothermic and is catalyzed by a Fischer-Tropsch catalyst, typically a cobalt-based catalyst, under conditions of high temperature (typically at least 180°C, e.g., 200°C or higher) and pressure (e.g., at least 10 bar). A product mixture is obtained, where n typically ranges from 1 to about 90. It is desirable to minimize methane selectivity in the product mixture, i.e., the proportion of methane (n=1), and maximize selectivity to C5 and higher (n≧5) paraffins, typically to levels of 90% or higher. Maximizing carbon monoxide conversion is also desirable. Preferably, at least about 70% w / w of the product mixture is distributed between n=10 and n=30.

[0004] The hydrogen and carbon monoxide feedstock is typically synthesis gas.

[0005] During the Fischer-Tropsch reaction, the catalyst gradually deactivates, reducing its effectiveness and requiring a gradual increase in temperature to maintain acceptable carbon monoxide conversion. This is described by Steynberg et al., "Fischer-Tropsch catalyst deactivation in commercial microchannel reactor operation," Catalysis Today 299 (2018), pp. 10-13.

[0006] It is possible to regenerate the catalyst periodically over a period of time, which can be done in situ, for example, by subjecting the catalyst to dewaxing, oxidation, and reduction processes. However, there comes a point in the life of the catalyst when the accumulation of non-renewable pollutants such as sulfur and other non-renewable deactivation mechanisms such as sintering render the catalyst ineffective. At this point, the catalyst must be discharged from the reactor and replaced with fresh catalyst.

[0007] A number of different reactor types are known for performing Fischer-Tropsch synthesis, including fixed-bed reactors, slurry bubble-column reactors (SBCRs), and microchannel reactors (Rytter et al., "Deactivation and Regeneration of Commercial Type Fischer-Tropsch Co-Catalysts - A Mini-Review," Catalysts 2015, 5, pp. 478-499 at pp. 482-483).

[0008] Microchannel reactors are disclosed in applicant's WO2016201218, which is incorporated by reference, as well as in LeViness et al., "Velocys Fischer-Tropsch Synthesis Technology - New Advances on State-of-the-Art," Top Catal 2014 57, pp 518-525. Such reactors have the particular advantage of allowing very efficient heat removal due to the high ratio of heat exchange surface area to microchannel (and therefore catalyst) volume.

[0009] However, microchannel reactors present special challenges when it is necessary to evacuate catalyst, especially spent catalyst that may have deteriorated within the microchannels over thousands of hours of plant operation. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] WO2016201218 [Patent Document 2] U.S. Patent Application Publication No. 2009252658 [Patent Document 3] WO2008030467 [Patent Document 4] U.S. Patent Application Publication No. 20120095268 [Non-patent literature]

[0011] [Non-Patent Document 1] Steynberg et al., “Fischer-Tropsch catalyst deactivation in commercial microchannel reactor operation,” Catalysis Today 299(2018), pp10-13 [Non-patent document 2] Rytter et al., "Deactivation and Regeneration of Commercial Type Fischer-Tropsch Co-Catalysts - A Mini-Review", Catalysts 2015, 5, pp478-499 at pp482-483 [Non-patent document 3] LeViness et al., "Velocys Fischer-Tropsch Synthesis Technology - New Advances on State-of-the-Art", Top Catal 2014 57, pp518-525 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention particularly, but not exclusively, relates to the removal of spent catalyst from microchannel reactors. Microchannel reactors typically include a microchannel architecture. Multiple The process layer includes a microchannel architecture, for example, a corrugated ridge located within the process layer. Multiple Process layer Multiple It effectively divides the process into a linear array of process channels (process microchannels). The microchannel architecture is typically thinner than the pressure boundary (and may be of a different material than the pressure boundary) and may be more easily damaged in harsh physical conditions, such as those that may be required to evacuate spent catalyst from the microchannels.

[0013] Due to the relatively small cross-section of the microchannels of such reactors, it has proven difficult to remove spent catalyst from the microchannels of these reactors. Attempts to remove spent catalyst by mechanical means (e.g., hammering) or using steam or high-pressure hot water, as described in applicant's U.S. Patent Application Publication No. 2009252658, have resulted in insufficient catalyst recovery, typically less than 50% of the original catalyst load.

[0014] It is also known from U.S. Patent Application Publication No. 2009252658 to remove spent catalyst from the microchannels of a Fischer-Tropsch reactor by placing an ultrasonic generating head in sonic contact with the microchannel and applying ultrasonic energy to the microchannel. However, this method also has certain practical disadvantages. In particular, it has been found that existing ultrasonic equipment and techniques are excessively slow and / or incomplete in removing spent catalyst from the microchannels. [Means for solving the problem]

[0015] The present invention provides a process for removing a particulate catalyst from a packed catalyst bed in a process channel of a microchannel reactor, comprising: Multiple Process Channel One consisting of A linear array of (linear array) hermetically sealing the distal end of The relevant In the array Multiple forming a blocked process channel; Multiple The process includes directing a high velocity gas stream into the open proximal end of the process channel, the velocity of the gas stream being sufficient to raise the pressure in at least a portion of the closed process channel to at least about 5 psig (34,473 Pa gauge), thereby creating a pressure gradient within the catalyst bed and / or between the catalyst bed and any void space adjacent to the catalyst bed within the closed process channel effective to displace particulate catalyst from the catalyst bed.

[0016] In another aspect, the present invention provides a process for removing a particulate catalyst from a process channel of a microchannel reactor, comprising: Multiple Hermetically sealing the distal end of the linear array of process channels The relevant In the array Multipleforming a closed process channel; directing a high velocity gas stream into the open proximal end of the process channel, the velocity of the gas stream being sufficient to raise the pressure in at least a portion of the closed process channel to at least about 5 psig; i. then removing the gas stream such that the concomitant release of pressure from the blocked process channel is effective to expel the particulate catalyst from the process channel; and / or ii. creating a pressure differential between the undrained and drained channel portions in the channel from which the catalyst has been partially drained, by the gas flow, effective to drive the particulate catalyst from the undrained channel portion to the drained channel portion; The present invention provides a process including:

[0017] Multiple The means provided for directing a high velocity gas stream into the open proximal end of the process channel may be referred to as an "air knife" for convenience, a term which should not be construed as limiting in any way.

[0018] Air Knife One at either end of the process channel arrangement while end From the other end The "proximal end" of a process channel is the end where the "air knife" is deployed (where the high velocity gas flow is directed), and the "distal end" is the end that is sealed off by an airtight seal. By definition, these ends are the ends where the "air knife" is relocated from one end of the process channel to the other. arrangement If so, the positions are reversed.

[0019] Most suitably, step i) may be initially deployed when the process channel is fully or at least largely emptied, whereas step ii) is subsequently deployed appropriately to expel the particulate catalyst in a free form into the emptied channel portion for subsequent removal from the process channel. Step ii) is believed to be effective in expelling the particulate catalyst from a partially emptied process channel because application of a gas flow to the channel increases the pressure in the undrained portion of the channel above the pressure of the (downstream, substantially empty) emptied channel portion. This pressure difference expels the packed catalyst in the undrained channel portion in a free form into the (downstream, substantially empty) emptied channel portion from which the catalyst can then be easily removed.

[0020] In the process of the present invention, an undrained process channel can be partially evacuated by a means including step i) and then further evacuated by a means including step ii), in which case the process can include in step ii) hermetically sealing an end of the process channel array opposite that sealed in step i) and directing a high velocity gas flow into the process channel at the end opposite that in step i).

[0021] In some embodiments of the invention, the velocity of the gas flow is sufficient to raise the pressure in at least a portion of the blocked process channel to about 5 to about 20 psig (34,473 to about 137,895 Pa gauge), preferably about 8 to about 15 psig (55,158 to about 103,421 Pa gauge), and can be, for example, at least about 10 psig (68,947 Pa gauge). The pressure will not be uniform in the process channel unless the process channel is at least substantially completely emptied of catalyst.

[0022] The relative rate at which pressure is increased (and / or subsequently released) in a blocked process channel, such as between a packed catalyst bed and any void space adjacent to the catalyst bed, can also be an important factor in successfully purging spent catalyst from the channel. Preferably, the pressure in the blocked process channel is increased by at least about 0.01 psi per msec, more preferably in the range of about 0.05 to about 0.5 psi per msec, in the processes of the present invention. Removal of the gas flow, as in step i) above, can similarly rapidly reduce the pressure in any vacant portion of the process channel, e.g., by at least about 0.01 psi per msec, more preferably in the range of about 0.05 to about 0.5 psi per msec, creating a pressure differential between the slow depressurization portion of the process channel (at the catalyst bed) and the fast depressurization portion of the process channel (in any vacant space adjacent to the catalyst bed), facilitating the expulsion of catalyst particles. When a gas flow is introduced into the channel, as in step ii) above, thereby increasing the pressure in the undrained portion of the channel above the pressure in the evacuated (downstream, substantially empty) channel portion, this pressure differential can be gradually generated by the pressure increase in the catalyst bed prior to any concomitant pressure increase in the vacant space adjacent the end of the catalyst bed downstream from application of the gas flow.

[0023] The mechanism for expelling spent catalyst is believed to be at least partially related to the inherent resistance to air flow through the tightly packed particles. Once high pressure is achieved within the process channel, removal of the high-velocity gas source encourages the pressurized gas within the process channel to exit the channel. The inherent flow resistance of the catalyst bed creates a pressure gradient across the catalyst particles, which exerts a force on the particles in the direction of the gas escape, resulting in the expulsion of the catalyst.

[0024] In step i), once the pressurized gas penetrates the packed component, it tends to escape from that component (toward the proximal end) as soon as the source of pressurized gas is removed. This tendency, combined with the airflow resistance of the tightly packed component, results in catalyst expulsion, as the pressurized gas attempts to escape the tightly packed component at a rate greater than would be accounted for by the natural escape path through the component. This can be most easily understood by considering a half-evacuated process channel, where catalyst particles reside only toward the undrained distal end. When gas flow is applied to a half-evacuated process channel, pressure rises throughout the entire channel, including through the undrained portion of the channel. When the gas flow is removed, pressure is quickly released from the evacuated proximal end of the channel, and the subsequent escape of gas from the undrained distal end results in expulsion as described above.

[0025] The same principles may apply to step ii), with the difference that removing the gas flow may not be necessary for the expulsion to occur. Partially evacuating the channel by step i) (or by some other means) results in a channel that is tightly packed with catalyst at one of its ends and substantially empty (evacuated) at the other. Hermetically sealing the substantially empty end and applying a gas flow to the filled end increases the pressure within the packed catalyst relative to the downstream, empty channel portion. This pressure difference drives the packed catalyst in the undrained channel portion in free form into the (downstream, substantially empty) evacuated channel portion, from which the packed catalyst can then be easily removed.

[0026] Microchannel reactors often contain fragile architecture within the process channels, such as corrugated structures that house particulate catalysts. In this case, to prevent or minimize damage to the process channel architecture, the process of the present invention utilizes spacer members that: Multiple Opening the proximal end of a linear array of process channels toThe method can include positioning a spacer member adjacent to the opening with at least one overlapping aperture or gap, and directing a high velocity gas flow into the process channel through the at least one aperture or gap.

[0027] Microchannel reactors typically include: Multiple Process Channel One consisting of A linear array of (linear array) Form One Includes microchannel architecture.

[0028] Typically, the particulate catalyst removed in the process of the present invention is spent catalyst.

[0029] Preferably, the reactor comprises: Multiple Process Channel Multiple In cases where a fragile microchannel architecture is included within the process channel and thus is desired to include spacer members, preferably Multiple Each layer of process channels is provided with such spacer members that extend across the width of the layer. Both of these features facilitate rapid and effective catalyst removal.

[0030] Preferably, the gas flow is Multiple Continuous layer of process channel Multiple This feature facilitates rapid and effective catalyst removal.

[0031] Preferably, the gas flow is generated by an elongated slot opening, the slot opening comprising: Multiple elongated in the direction of said linear array of process channels; One layer of multiple process channels, 2 or more, preferably 10 or more, more preferably 20 or more, most preferably all Nopu This feature equalizes the pressure within the process channel, and therefore the forces acting on the process channel walls, protecting them from damage by gas flow.

[0032] The lateral dimensions of the slot openings may be smaller than the corresponding lateral dimensions of the apertures or voids in the spacer members, if present, this feature providing additional protection for the process channel walls.

[0033] In certain embodiments of the present invention, the spacer elements provide an important technical protection. Without the spacer elements, high-velocity gas flows directed into the process channels tend to damage any microchannel architecture in those channels. Thus, for example, if the microchannel architecture includes corrugated inserts or corrugations, such as those described in applicant's WO2008030467, which is incorporated herein by reference, they may be damaged if the spacer elements used in the process of the present invention are omitted.

[0034] Multiple Process Channel One consisting of A linear array is One It forms the process layer. Multiple The process layer typically has a length, a height, and a width, and a rectangular configuration. Typical lengths are about 100 mm to about 1000 mm, or about 200 mm to about 600 mm. Typical heights are about 3 mm to about 10 mm, or about 5 mm to about 7 mm. Typical widths are about 50 mm to about 800 mm, or about 100 mm to about 300 mm. The microchannel architecture within the process layer typically has an approximate width of 0.5 to 2 mm, or 0.75 to 1.5 mm, and an approximate length and height of the process layer. Multiple Process channel ( Multiple Process Microchannel One Channels with widths of 2 mm or less are generally considered micro-process channels, or microchannels, and have a particularly high surface area to volume ratio that favors heat exchange with the reactor during production and facilitates process control and selectivity.

[0035] Preferably, the velocity of the gas stream entering the open proximal end of the process channel or aperture or void in the spacer member is at least about 250 m / s, preferably at least about 300 m / s, and most preferably at least about 330 m / s, which may be supersonic. These values ​​have been found to result in a rapid and efficient buildup of pressure within the process channels for effective and rapid catalyst removal from those channels upon pressure release, while preventing damage to the microchannel architecture of the process channels due to the presence of the spacer member in certain embodiments of the present invention.

[0036] The process channels are closed at their distal ends, thereby increasing the pressure within the process channels when gas flow enters them at their proximal ends. Typically, the pressure within the process channels prior to operation of the process of the present invention is ambient, i.e., atmospheric pressure. The pressure within the process channels typically increases from ambient to greater than 5 psig (34,473.5 Pa gauge), preferably to or greater than 20 psig (137,895 Pa gauge), upon application of the gas flow.

[0037] The distal end may optionally be sealed by any suitable means, such as by durable aluminum adhesive tape or other sealant means.

[0038] Preferably, the gas stream is air, but any other suitable, preferably inert, gas may be used.

[0039] Multiple The process channel openings are linear arrays (linear) Preferably, the gas streams are generated by nozzles having elongated openings parallel to the linear array and mounted on a carriage for lateral linear movement, the carriage being supported by the reactor. This feature allows for a relatively compact device that can be easily attached and detached from the reactor.

[0040] According to the present invention, a particulate catalyst is contained Multiple Also provided is a microchannel reactor comprising a linear array of process channels, the linear array having at its distal end means for hermetically sealing the process channels, and at its proximal end having an opening, a spacer member having at least one aperture or void overlapping the opening, and means for movably mounting a nozzle for directing a high velocity gas stream into the process channels through the at least one aperture or void.

[0041] It is also contemplated within the scope of the present invention that multiple high velocity gas flow nozzles may be used simultaneously, where the nozzles may be used together to discharge catalyst from a single core of the reactor and / or may be used to discharge catalyst from multiple cores of the reactor simultaneously.

[0042] The air flow through the nozzle may be pulsed or continuous.

[0043] Further preferred features are defined in the dependent claims.

[0044] A preferred embodiment of the present invention will now be described, by way of example only, with reference to Figures 1 to 7 of the accompanying drawings. [Brief explanation of the drawings]

[0045] [Figure 1] 1 is a schematic perspective view of a microchannel reactor used in a preferred embodiment. [Figure 2] FIG. 2 is a schematic perspective view of a reactor core used in the reactor of FIG. 1. [Figure 3] FIG. 3 is a schematic perspective view of a portion of the process channel including the microchannel architecture used in the reactor core of FIGS. 1 and 2. [Figure 4] FIG. 4 is a schematic perspective view of an air knife and spacer member used to remove spent catalyst from the reactor core of FIG. 3. [Figure 5] 5 is a schematic elevation view from below showing the air knife of FIG. 4 traversing multiple layers of process microchannels of the reactor core of FIG. 2. [Figure 6] FIG. 5 is a schematic side view showing the air knife of FIG. 4 traversing multiple layers of process microchannels of the reactor core of FIG. 2. [Figure 7] FIG. 3 is a schematic perspective view from below showing the installation of spacer members on the underside of the reactor core of FIG. 2. [Figure 8] FIG. 7 is a schematic perspective view of the air knife of FIGS. 4 and 6 mounted on a linear carriage assembly. [Figure 9] FIG. 3 is a schematic perspective view of a linear carriage assembly in a retracted configuration mounted on the underside of the reactor core of FIG. 2. [Figure 10] FIG. 3 is a schematic perspective view of a linear carriage assembly in an extended configuration mounted on the underside of the reactor core of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0046] Details of one suitable microchannel Fischer-Tropsch reactor from which catalyst may be removed by a process according to the present invention are shown below with reference to FIGS.

[0047] Referring to FIG. 1 , microchannel reactor 200 includes containment vessel 210 that houses or accommodates three microchannel reactor cores 220. In other embodiments, containment vessel 210 can be used to house or accommodate from 1 to about 16 microchannel reactor cores, or from 1 to about 8 microchannel reactor cores, or from 1 to about 4 microchannel reactor cores. Containment vessel 210 can be a pressurizable vessel. Containment vessel 210 includes inlets and outlets 245 that allow reactants to flow into and out of microchannel reactor core 220. Heat exchange fluid is supplied to the microchannel reactor cores through inlets 230 and is withdrawn from similarly positioned outlets on the opposite side of the reactor.

[0048] Inlet 245 may be connected to a header or manifold (not shown) provided for flowing reactants to the process microchannels in each of the microchannel reactor cores. Inlet 230 may be connected to a header or manifold (not shown) provided for flowing a heat exchange fluid, such as saturated water, to the heat exchange channels in each of the microchannel reactor cores. One of outlets 245 may be connected to a manifold or footer (not shown) provided for flowing products from the process microchannels in each of the microchannel reactor cores. One of heat exchange fluid outlets 230 may be connected to a manifold or footer (not shown) provided for flowing heat exchange fluid from the heat exchange channels in each of the microchannel reactor cores.

[0049] The containment vessel 210 may be constructed of any suitable material sufficient to withstand the operating pressures that may develop within the microchannel reactor core. For example, the shell 240 and reinforcing ribs 242 of the containment vessel 210 may be constructed from cast steel or stainless steel. The flanges, couplings, and pipes may be constructed from stainless steel, for example. The containment vessel 210 may have a diameter of, for example, 1.5 m. The axial length of the containment vessel 210 may be, for example, 1.5 m for each reactor core positioned in the containment vessel, i.e., 5.5 m for a four-core reactor.

[0050] Referring to FIG. 2, the microchannel reactor core 220 contains alternating stacks of layered units 300 of process microchannels 310 and layered units 350 of heat exchange channels 355 .

[0051] The microchannel reactor core 220 may optionally include multiple plates in a stack that defines multiple process layers and multiple heat exchange layers, each plate having a periphery, and the periphery of each plate or shim welded to the periphery of the next adjacent plate to provide a periphery seal for the stack, as shown in U.S. Patent Application Publication No. 20120095268, which is incorporated herein by reference.

[0052] The microchannel reactor core 220 may optionally have the form of a solid block having six sides that are square or rectangular. The microchannel reactor core 220 may optionally have the same cross section along its length. The microchannel reactor core 220 may optionally be in the form of a parallelepiped or solid block or prism. The microchannel reactor core 220 may have a length, width, and height of, for example, 1 m.

[0053] Located within the process microchannels 310 is a Fischer-Tropsch catalyst 500, which may be in any suitable form, for example, a fixed bed of particulate solids.

[0054] 3 shows a microchannel architecture in the form of a corrugated sheet 315 sandwiched between plates 316 and 317, defining process microchannels 310 on either side of the sheet 315. For clarity, a Fischer-Tropsch catalyst 500 is shown in only one of the microchannels, but in reality each microchannel 310 would be filled with a Fischer-Tropsch catalyst 500. Further details of this construction are disclosed in WO2008030467, which is incorporated herein by reference.

[0055] The Fischer-Tropsch catalyst 500 may optionally comprise cobalt and a support. The catalyst may optionally have a cobalt loading in the range of about 10 to about 60 wt%, or about 15 to about 60 wt%, or about 20 to about 60 wt%, or about 25 to about 60 wt%, or about 30 to about 60 wt%, or about 32 to about 60 wt%, or about 35 to about 60 wt%, or about 38 to about 60 wt%, or about 40 to about 60 wt%, or about 40 to about 55 wt%, or about 40 to about 50 wt% cobalt.

[0056] The Fischer-Tropsch catalyst 500 may optionally further comprise a precious metal. The precious metal may be, for example, one or more of Pd, Pt, Rh, Ru, Re, Ir, Au, Ag, and Os. The precious metal may be one or more of Pt, Ru, and Re. The precious metal may be Ru. Alternatively, or additionally, the precious metal may be Pt. The Fischer-Tropsch catalyst may optionally comprise from about 0.01 to about 30% total precious metal (based on the combined weight of all precious metals present as a total weight percent of the catalyst precursor or activated catalyst), or optionally from about 0.05 to about 20% total precious metal, or optionally from about 0.1 to about 5% total precious metal, or optionally about 0.2% total precious metal.

[0057] The Fischer-Tropsch catalyst 500 may optionally include one or more other metal-based components as promoters or modifiers. These metal-based components may also optionally be present in the catalyst precursor and / or activated catalyst as carbides, oxides, or elemental metals. Suitable metals for the one or more other metal-based components may be, for example, one or more of Zr, Ti, V, Cr, Mn, Ni, Cu, Zn, Nb, Mo, Tc, Cd, Hf, Ta, W, Re, Hg, Tl, and a 4f-block lanthanide. Suitable 4f-block lanthanides may be La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and / or Lu. The metal of the one or more other metal-based components may be, for example, one or more of Zn, Cu, Mn, Mo, and W. The metal of the one or more other metal-based components can be, for example, one or more of Re and Pt. The catalyst may optionally include from about 0.01 to about 10% total other metals (based on the combined weight of all other metals as a total weight percent of the catalyst precursor or activated catalyst), or optionally from about 0.1 to about 5% total other metals, or optionally about 3% total other metals.

[0058] The Fischer-Tropsch catalyst 500 may optionally be derived from a catalyst precursor that can be activated to produce the Fischer-Tropsch catalyst by, for example, heating the catalyst precursor in hydrogen and / or a hydrocarbon gas (e.g., methane) or in hydrogen and / or a hydrocarbon gas diluted with another gas, such as nitrogen and / or methane, to convert at least a portion of the carbide or oxide to elemental metal. In the active catalyst, cobalt may optionally be at least partially in the form of its carbide or oxide.

[0059] The Fischer-Tropsch catalyst 500 may optionally include a catalyst support. The support may optionally include a refractory metal oxide, carbide, carbon, nitride, or a mixture of two or more thereof. The support may optionally include alumina, zirconia, silica, titania, or a mixture of two or more thereof. The surface of the support may optionally be modified by treating the surface with silica, titania, zirconia, magnesia, chromia, alumina, or a mixture of two or more thereof. The materials used for the support and the materials used to modify the support may differ. The support may optionally include silica, and the surface of the silica may optionally be treated with a refractory solid oxide, such as titania. The material used to modify the support may be used to increase the stability of the supported catalyst (e.g., by reducing deactivation).

[0060] The catalyst support may optionally contain up to about 30 wt. % of an oxide (e.g., silica, titania, magnesia, chromia, alumina, zirconia, or a mixture of two or more thereof) used to modify the surface of the support, or, for example, from about 1 wt. % to about 30 wt. %, or from about 5 wt. % to about 30 wt. %, or from about 5 wt. % to about 25 wt. %, or from about 10 wt. % to about 20 wt. %, or from about 12 wt. % to about 18 wt. The catalyst support may optionally be in the form of a structured shape, pellet, or powder. The catalyst support may optionally be in the form of a particulate solid. While not wishing to be bound by theory, it is believed that the surface treatments described herein help to protect the Co from sintering during Fischer-Tropsch operation.

[0061] The deactivation rate of the Fischer-Tropsch catalyst 500 may optionally be such that it can be used in Fischer-Tropsch synthesis for more than about 300 hours, or more than about 3,000 hours, or more than about 12,000 hours, or more than about 15,000 hours, all before recovery or regeneration of the catalyst is required.

[0062] The Fischer-Tropsch catalyst 500 may optionally be used for an extended period of time (e.g., greater than 300 hours) at a deactivation rate of less than about 1.4% per day, or less than about 1.2% per day, or between about 0.1% and about 1% per day, or between about 0.03% and about 0.15% per day.

[0063] The Fischer-Tropsch catalyst 500 can have any size and geometric configuration that fits within the process microchannel 310. The catalyst may optionally be in the form of a particulate solid (e.g., pellets, powder, fiber, etc.) having a median particle size of about 1 to about 1000 μm (microns), or about 10 to about 750 μm, or about 25 to about 500 μm. The median particle size may optionally be in the range of 50 to about 500 μm, or about 100 to about 500 μm, or about 125 to about 400 μm, or about 170 to about 300 μm. In one example, the catalyst may be in the form of a fixed bed of particulate solid.

[0064] The microchannel reactor core 220 can include, for example, six layers 350 of heat exchange channels 355 .

[0065] 3, each process microchannel 310 can have, for example, a height (h) of 6.35 mm and a width (w) of 1 mm. The length of each process microchannel can be, for example, 610 mm.

[0066] Multiple Each unit or layer 300 of process microchannels 310 may have, for example, hundreds of process microchannels 310. The process microchannels 310 may have a cross section having any shape, e.g., square, rectangular, circular, semicircular, etc. The clearance height of each process microchannel 310 may be considered to be the smaller of the clearance dimensions perpendicular to the direction of flow of reactants and products through the process microchannel.

[0067] Each unit or layer 350 of heat exchange channels 355 may have, for example, hundreds of heat exchange channels. The heat exchange channels 355 may be microchannels or may have larger dimensions that are classified as non-microchannels.

[0068] The microchannel reactor core 220 can be made from any material that provides sufficient strength, dimensional stability, and heat transfer properties to enable the operation of the desired process. These materials can include, for example, aluminum, titanium, nickel, platinum, rhodium, copper, chromium, alloys of any of the foregoing metals, brass, steel (e.g., stainless steel), quartz, silicon, or combinations of two or more thereof. Each microchannel reactor can optionally be constructed from stainless steel, with one or more corrugated copper or aluminum used to form the channels.

[0069] The microchannel reactor core 220 may optionally be fabricated using known techniques, including, for example, wire electrical discharge machining, conventional machining, laser cutting, photochemical machining, electrochemical machining, molding, water jet, stamping, etching (e.g., chemical etching, photochemical etching, or plasma etching), and combinations thereof.

[0070] The microchannel reactor core 220 may optionally be constructed by forming plates with portions removed to allow flow passage. Stacks of plates can be assembled to form an integrated device, for example, by diffusion bonding, laser welding, diffusion brazing, conventional welding, additive manufacturing, and similar methods. The microchannel reactor can be assembled, for example, using a combination of plates and partial plates or strips. In this method, channels or void areas can be formed by assembling strips or partial plates to reduce the amount of material required.

[0071] The microchannel reactor core 220 may optionally include multiple plates in a stack defining multiple process layers and multiple heat exchange layers, each plate having a periphery, and the periphery of each plate or shim being welded to the periphery of the next adjacent plate to provide a periphery seal for the stack, as shown in U.S. Patent Application Publication No. 20120095268, which is incorporated herein by reference.

[0072] Containment vessel 210 may optionally include a control mechanism that maintains the pressure within the containment vessel at a level that is at least as high as the internal pressure within microchannel reactor core 220. The internal pressure within containment vessel 210 may optionally be in a range of about 10 to about 60 atmospheres, or about 15 to about 30 atmospheres, during operation of a syngas conversion process (e.g., a Fischer-Tropsch process). The control mechanism that maintains the pressure within the containment vessel may optionally include a check valve and / or a pressure regulator. The check valve or regulator may optionally be programmed to function at any desired internal pressure for the containment vessel. Any or all of these may be used in conjunction with a system of piping, valves, controllers, etc. to ensure that the pressure within containment vessel 210 is maintained at a level that is at least as high as the internal pressure within microchannel reactor core 220. This is done in part to protect the welds used to form microchannel core 220. A significant drop in pressure within containment vessel 210 without a corresponding drop in internal pressure within microchannel reactor core 220 can result in costly fracture of welds within microchannel reactor core 220. The control mechanism may optionally be designed to allow bypass of one or more process gases to the containment vessel when the pressure exerted by the containment gas is reduced.

[0073] The apparatus and process for removing spent Fischer-Tropsch catalyst from the process microchannels 310 of the reactor will now be described with reference to Figures 4-10.

[0074] Referring to FIG. 4, an air knife 1 is shown which is connected to a compressed air source (not shown) and has a slit having a width approximately equal to the width of the process microchannel unit or layer 300 which defines a high velocity air jet 4.

[0075] An elongated guard or spacer 2 having two parallel slots 3 is shown aligned with the air knife 1 so that an air jet 4 passes through one of the parallel slots. The length of the air knife slit is equal to or slightly longer than the length of the slots 3, and in either case corresponds to the overall width W (FIG. 2) of the reactor core 220. In use, the guard or spacer 2 is Multiple 7, an array of such guard members 2 is configured such that the air jets 4 pass through successive slots in successive guard members and thence through successive slots in the reactor core 220. Multiple The column is provided with a process microchannel 310 into which the liquid enters.

[0076] As best seen in FIG. 6 , the protective member or spacer 2 is positioned below the coolant panel 350, with the slots in the protective member or spacer 2 aligned with the process microchannels 310. The coolant panel 350 includes coolant channels (not shown). The length of the spacer strip below the coolant panel spans the entire installed reactor core, determining the width of the reactor. The depth of the protective member (vertical in FIG. 6 ) is suitably 10 mm to 50 mm, e.g., 25 mm. The alignment of the slots with the process microchannels also results in alignment of the spacer strips with the corrugation-coolant panel contacts, which, in use, serve to protect those contacts from the full force of the gas flow directed through the body of the slot. The depth of the protective member can also be appropriately selected with respect to this most vulnerable location within the process channel.

[0077] Referring to FIG. 6A, in a modified protective member, the slots 3 can be omitted and each protective member 2 shown in FIG. 5 can be replaced by three narrower, spaced apart protective members 2A, 2B and 2C positioned individually across each coolant layer 350, with air jets 4 directed through gaps g between the protective members.

[0078] As shown in FIG. 5, the air knife 1 is a continuous Multiple The catalyst 500 is extruded across the column. The width W of the micro-process channel is suitably 1 mm and the clearance height h is suitably 6.35 mm.

[0079] When air knife 1 is positioned in line with any given guard, the distance from the air knife slit to guard 2 is as short as possible within practical tolerances, typically between 0.5 and 19 mm. The length of the air knife slit is equal to or slightly longer than the width of the process layer for all cores corresponding to the overall reactor width.

[0080] The dimensions of the air knife slit and the upstream air pressure are set so that air flows through the slit at near-sonic, near-sonic, or even supersonic speeds. The slit width is typically in the range of 150-180 mm, but can be up to or slightly wider than the width of the process layer.

[0081] When in use, the air knife 1 should be moved from one end of the reactor to the other in 0.01 to 0.2 ms. -1 After traversing the entire length of the underside of the reactor core 220 or a selected portion of the reactor core, the air knife moves at a similar speed back to its starting position at the other end or portion of the reactor core 220. This movement is repeated with a continuous flow of air through the air knife slits until catalyst flow from the channels stops. The reactor is then inspected to determine if complete catalyst evacuation has been achieved.

[0082] For any partially undrained channels, the process of the invention can then be deployed in step ii) by unsealing the sealed end of the process channel and then hermetically sealing the opposing end of the linear array of process channels to form a sealed process channel in the array, and by using spacer members Multiple By positioning a spacer member adjacent to the openings of the (currently) open ends of the linear array of process channels with at least one aperture or void overlapping the openings, and directing a high velocity gas stream into the process channels through the at least one aperture or void, the velocity of the gas stream being sufficient to raise the pressure in the closed process channel to at least about 5 psig in at least a portion of the closed process channel, the concomitant increase in pressure in the undrained catalyst causes the packed catalyst in the undrained channel portion to be expelled in free form into the (downstream, substantially empty) drained channel portion. Preferably, the pressure differential between the pressure in the packed catalyst bed and the pressure in the adjacent unpacked portion of the process microchannel is at least about 1 psig, and preferably at least about 2 psig.

[0083] Alternatively to step ii), the process of the present invention in step i) can be performed by applying the process of the present invention from the opposite side of the process channel, i.e., by unsealing the sealed end of the process channel and then Multiple hermetically sealing opposite ends of the linear array of process channels to form closed process channels in the array; and spacer members MultipleThis can be repeated by positioning a spacer member adjacent to the opening with at least one aperture or void overlapping the opening of the (then) open end of the linear array of process channels, directing a high velocity gas stream into the process channels through the at least one aperture or void, the velocity of the gas stream being sufficient to raise the pressure in the closed process channel to at least about 34,473 Pa gauge (about 5 psig), and then removing the gas stream such that the concomitant release of pressure from the closed process channel is effective to expel the particulate catalyst from the process channel.

[0084] If there are a few remaining channels that contain some catalyst, non-automated methods such as solvent washing and / or mild physical excitation can be applied to those channels.

[0085] As best seen in Figure 8, the air knife 1 is carried on a slide 6, which is attached to four support arms 7, the ends of which have fasteners (e.g., machine screws) that secure the resulting assembly 5 to the underside of the reactor core 220. The protective member 2 is not shown in this view.

[0086] In operation, the air knife 1 is moved along the length of the reactor, sequentially directing an air flow into the gaps between the spacer strips, causing air to pass successively upward through the air knife slits, which extend across all of the process microchannels 310 at 315.

[0087] As the air flow traverses the depth of the protective member 2 (FIGS. 5 and 6) and reaches the process microchannels 310, an air blast impinges on the catalyst 500 in each reactor channel, increasing the pressure within the channel (which is sealed at its distal end) to greater than 5 psig (34,473 Pa gauge), or up to or above 10 psig (68,947 Pa gauge). As the air knife passes across the channel, the pressure is released, forcing at least a portion of the catalyst within the channel into the released flow. The air knife continues to move back and forth along the length of the reactor at a preset speed, propelled by the automated air knife movement system, until no more catalyst is removed from the reactor.

[0088] The extruded catalyst can be collected in a vacuum-drawn chamber (not shown) located below the reactor core 200 .

[0089] As best seen in Figures 2, 3, and 5, each row of process microchannels 310 is defined by a corrugated sheet 315 positioned between the facing walls of adjacent cooling panels 350. The corrugated sheet is made of a heat-conducting material, typically copper, and is shaped to form a plurality of vertical reactor channels 310. The walls of the coolant panels are typically parallel stainless steel plates. The parallel plates are usually internally cooled by a coolant fluid. During operation, the reactor channels are filled with a particulate catalyst material.

[0090] After the spent catalyst 500 is removed, it can be replaced with a new catalyst.

[0091] The catalyst removal method described may be applied to chemical reactors other than Fischer-Tropsch reactors to remove spent catalyst from that chemical reactor.

[0092] The variations presented above may be combined in any combination.

Claims

1. 1. A process for removing catalyst from a packed catalyst bed in a process channel of a microchannel reactor, comprising: hermetically sealing a distal end of a linear array of the process channels to form a sealed process channel in the linear array, the linear array of process channels forming a process layer; directing a high velocity gas stream toward the proximal end forming an open opening of each of the plurality of process channels toward the distal end, the velocity of the gas stream being sufficient to raise the pressure in at least a portion of the closed process channel to at least 34,473 Pa gauge (5 psig); thereby creating a pressure gradient within the catalyst bed and / or between the catalyst bed and any void space adjacent the catalyst bed in the enclosed process channel effective to displace particulate catalyst from the catalyst bed. Including, The process channels of the linear array are configured such that the openings at the proximal ends of the process channels are arranged consecutively in a straight line.

2. 1. A process for removing particulate catalyst from a process channel of a microchannel reactor, comprising: hermetically sealing a distal end of a linear array of the process channels to form a sealed process channel in the linear array, the linear array of process channels forming a process layer; directing a high velocity gas stream toward the proximal end forming an open opening of each of the plurality of process channels toward the distal end, the velocity of the gas stream being sufficient to raise the pressure in at least a portion of the closed process channel to at least 34,473 Pa gauge (5 psig); i. then removing said gas stream such that the concomitant release of pressure from said blocked process channel is effective to expel particulate catalyst from said process channel; and / or ii. causing said gas flow to create a pressure differential between an undrained process channel portion and an emptied process channel portion in a process channel from which catalyst has been partially emptied, said pressure differential effective to drive particulate catalyst from said undrained process channel portion to said emptied process channel portion. Including, The process channels of the linear array are configured such that the openings at the proximal ends of the process channels are arranged consecutively in a straight line.

3. i. removing the gas stream such that the concomitant release of pressure from the blocked process channel is effective to expel particulate catalyst from the process channel; and / or ii. causing said gas flow to create a pressure differential between an undrained process channel portion and an emptied process channel portion in a process channel from which catalyst has been partially emptied, said pressure differential effective to drive particulate catalyst from said undrained process channel portion to said emptied process channel portion.

2. The process of claim 1, comprising:

4. 3. The process of claim 2, wherein in step ii), the particulate catalyst is expelled in free form into the evacuated process channel portion for subsequent removal from the process channel.

5. 3. The process of claim 2, wherein the undrained process channel is partially evacuated by the means comprising step i) and then further evacuated by the means comprising step ii).

6. In step ii), hermetically sealing the ends of the linear array of process channels opposite those sealed in step i); directing said high velocity gas stream into said plurality of process channels at said ends opposite to those in step i); 6. The process of claim 5, comprising:

7. 3. The process of claim 2, wherein the gas flow is moved across a plurality of openings in a plurality of successive process layers that are arranged in a direction perpendicular to the direction in which the openings at the proximal ends of the plurality of process channels are arranged in a linear sequence.

8. 3. The process of claim 2, wherein the reactor comprises a plurality of the process layers arranged in series in a direction perpendicular to the direction in which the openings at the proximal ends of the plurality of process channels are arranged in series in a straight line.

9. The process described in Claim 8, wherein each of the plurality of process layers is provided with a spacer member extending across the width of the process layer in a direction in which the proximal end openings are arranged in a linear sequence.

10. positioning a spacer member adjacent the proximal end opening of the linear array of process channels, the spacer member having at least one aperture or void overlapping the proximal end opening; directing the high velocity gas stream through the at least one aperture or gap into the plurality of process channels; 3. The process of claim 2, comprising:

11. The process of claim 10 , wherein the gas flow is generated by an elongated slotted opening, the lateral dimension of the slotted opening being smaller than the corresponding lateral dimension of the aperture or gap in the spacer member.

12. The process of claim 10, wherein the aperture or void in the spacer member is elongated in a direction in which the proximal end openings of the plurality of process channels are arranged in a linear sequence and extends across two or more of the openings of the plurality of process channels of the one process layer.

13. 3. The process of claim 2, wherein the velocity of the gas stream entering the process channel is at least 250 m / s.

14. 3. The process of claim 2, wherein the pressure in the process channel increases from ambient pressure to or greater than 20 psig (137,895 Pa gauge) upon application of the gas flow.

15. 3. The process of claim 2, wherein the gas flow is generated by a nozzle having an elongated opening parallel to a direction in which the openings at the proximal ends of the plurality of process channels are arranged in a linear sequence and mounted on a carriage for linear movement in a direction perpendicular to that direction, the carriage being supported by the reactor.

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