Patent ID: 12251758

DETAILED DESCRIPTION OF THE DISCLOSURE

As used herein, the term “reactionary process” refers to a process that occurs when at least one active agent is exposed to at least one reactant. For example and without limitation, reactionary processes include catalytic processes, adsorption processes, and photocatalytic processes.

As used herein, the term “ink” refers to a substance used for a printing process such as an additive manufacturing or 3-dimensional printing process. For example, an ink may comprise a hydrophobic substance that is deposited onto a surface to form a 3-dimensional object.

In this disclosure, systems and methods for additively manufacturing structures are described. For example, the additively manufactured structures may include one or more materials formed from a binder and metal or metal oxide particles. The structures may be used for reactionary process such as adsorption and/or catalytic processes. The structures may provide improved performance (e.g., increased adsorption or a more efficient catalytic conversion) in comparison to known structures for reactionary processes.

FIG.1is a schematic diagram of an exemplary embodiment of an additive manufacturing system10for forming a structure such as a structure12, a structure30(shown inFIG.2), and a multi-material structure200(shown inFIG.6). The additive manufacturing system10includes a build platform14and a dispenser16. The dispenser16is configured to dispense a material, e.g., an ink, onto the build platform14. In some embodiments, the additive manufacturing system10includes a consolidation device, such as a heat source or a binder jet, configured to consolidate the material dispensed by the dispenser16.

The dispenser16is configured to dispense one or more materials18,20onto the build platform14. For example, the dispenser16may dispense a first material18and a second material20in a series of layers. In addition, the dispenser16may dispense the materials18,20in a desired pattern on the build platform14. Also, in some embodiments, the additive manufacturing system10may include a recoater assembly configured to distribute the materials18,20across the build platform14.

The materials18,20dispensed by the dispenser16may be any materials suitable for forming the structure12. In some embodiments, each material18,20includes a binder that causes the material to solidify, i.e., cure, as the structure12is exposed to the environment. In further embodiments, the additive manufacturing system10may include a heat source to at least partially control the curing of the material18,20.

In the illustrated embodiment, the dispenser16includes a plurality of nozzles22. Each nozzle22may be configured to dispense one of the materials18,20onto the build platform14. Accordingly, the dispenser16is configured to dispense a plurality of materials18,20onto the build platform14. In other embodiments, at least one nozzle22may be configured to dispense more than one material. For example, at least one of the nozzles22may be coupled to a plurality of material supplies and a valve or control device may control which material(s) are supplied to the nozzles. In alternative embodiments, the material18,20may be provided to the build platform14in any suitable manner. For example, in some embodiments, the material18,20is transferred from a hopper to the build platform14using a recoater assembly.

During operation of the additive manufacturing system10, the dispenser16is operated to deposit one or more of the materials18,20onto the build platform in a series of layers. For example, the first nozzle22of dispenser16may deposit a first material18onto the build platform14in a first layer. The second nozzle22may deposit a second material20onto or adjacent the first material18on the build platform14in a second layer. Additive manufacturing system10repeatedly deposits the materials18,20in the layers until the structure12includes a desired number of layers.

In the exemplary embodiment, the first material18and the second material20each include binders that cause the materials to solidify, i.e., cure, as the structure12is exposed to the environment. For example, in some embodiments, the materials18,20are each formed by mixing an active agent in a solvent including the respective binder and thereby forming a paste. The first material18and the second material20are able to be extruded and deposited on the build platform14in the paste form. In addition, the first material18and the second material20are configured to adhere together when the materials contact each other. For example, in some embodiments, the binder in the first material18and/or the binder in the second material20adheres to the other of the first material and the second material. The materials form a solid, contiguous structure when the materials cure. In alternative embodiments, the first material18and the second material20are adhered together in any suitable manner. For example, in at least some embodiments, a separate binder material is deposited between the first material18and the second material20.

Also, during operation of the additive manufacturing system10, the dispenser16is configured to move in vertical and horizontal directions (X-direction and Y-direction) relative to the build platform14in reference to the orientation of the additive manufacturing system10shown inFIG.1. In addition, the build platform14is configured to move in a horizontal direction (Z-direction) relative to the dispenser16. Accordingly, the dispenser16is able to deposit the materials in desired patterns and shapes on the build platform14and deposit the materials in a series of layers. In alternative embodiments, the build platform14may be moved in the vertical direction (Y-direction) relative to the dispenser16when the dispenser16deposits the layers of the materials18,20.

Moreover, in the exemplary embodiment, the additive manufacturing system10may include a computer control system, or controller24. For example, the controller24may include a processor, a memory, and a user interface including an input device and a display. The controller24may control operation of components of the additive manufacturing system10, such as one or more actuator systems26,28and the dispenser16, to fabricate the structure12. For example, the controller24controls the amount of the material18,20that is dispensed through each nozzle22of the dispenser16.

In the exemplary embodiment, the additive manufacturing system10is operated to fabricate the structure12from a computer modeled representation of the 3D geometry of the component. The computer modeled representation may be produced in a computer aided design (CAD) or similar file. The CAD file of the structure12is converted into a format that includes a plurality of build parameters for one or more layers of the structure12. In the exemplary embodiment, the structure12is modeled in a desired orientation relative to the origin of the coordinate system used in the additive manufacturing system10. The geometry of the structure12is sliced into one or more layers. Once the process is completed, an electronic computer build file (or files) is generated, including all of the layers. The build file is loaded into the controller24of the additive manufacturing system10to control the system during fabrication of each layer.

After the build file is loaded into the controller24, the additive manufacturing system10is operated to generate the structure12by implementing the additive manufacturing process. The exemplary additive manufacturing process does not use a pre-existing article as the precursor to the final structure; rather, the process produces structures from a raw material in a configurable form, such as particulate or paste. Additive manufacturing system10enables fabrication of structures using a broad range of materials, for example, and without limitation, metals, metal oxides, and group II metal carbonates, ceramics, glass, and polymers.

Moreover, in the exemplary embodiment, during operation of the additive manufacturing system10, the controller24is able to control the operation of the actuator system26,28to adjust the height and position of the dispenser16and/or the build platform14. In the exemplary embodiment, the dispenser16is moved vertically and horizontally using the actuator system26. In addition, the build platform14is moved horizontally using the actuator system28. In alternative embodiments, the dispenser16and/or the build platform14is moved in any manner that enables the additive manufacturing system10to operate as described herein.

FIG.2is a top view of a structure30formed using an additive manufacturing system.FIG.3is a perspective view of the additively manufactured structure30. The additively manufactured structure30includes a plurality of layers32and a material34formed from a binder and an active agent.

In the exemplary embodiment, the active agent is configured to cause a reaction when exposed to a reactant and includes a metal such as a metal oxide, a group II metal carbonate, and/or a metal nanoparticle. For example and without limitation, the active agent may include copper oxide, chromium oxide, nickel oxide, titanium oxide, tungsten oxide, magnesium oxide (derived from calcined magnesium carbonate), calcium oxide (derived from calcined calcium carbonate), porous carbon, silicon dioxide, yttrium oxide, molybdenum oxide, zirconium oxide, zinc oxide, gallium oxide, vanadium oxide, niobium oxide, iron oxide, indium oxide, tin oxide, lanthanum oxide, copper nanoparticles, aluminum oxide, cerium oxide, manganese oxide, cobalt oxide, lead oxide, cadmium oxide, rhodium oxide, scandium oxide, technetium oxide, ruthenium oxide, rhenium oxide, tantalum oxide, germanium oxide, thallium oxide, iridium oxide, palladium nanoparticles, palladium oxide, gold nanoparticles, silver nanoparticles, silver oxide, platinum nanoparticles, barium oxide (derived from calcined barium carbonate), strontium oxide (calcined strontium carbonate), and/or beryllium oxide (derived from calcined beryllium carbonate). As a result, the additively manufactured structure30is configured for use in reactionary processes such as a reactionary process involving catalytic conversion.

The material34may have a higher loading of the active agent than materials of an incipient impregnation process because the active agent is directly printed in the material34. Accordingly, the structure30is precisely customizable to provide desired reactive characteristics. For example, in some embodiments, the material34has a loading of the active agent that is greater than 10%. In some embodiments, the material34has a loading of the active agent that is in a range of about 15% to about 85%. In addition, the structure30may have greater disbursement of the active agent and improved activity during a reactionary process because the active agent is directly printed in the material34and is not formed from a precursor in the material34.

In addition, the active agent may be insoluble and may include particles that are sized to combine with the binder and facilitate printing of the metal. For example, the active agent may include particles having a diameter in a range of about 0.05 micrometers to about 100 micrometers. In some embodiments, the active agent includes particles having a diameter in a range of about 0.05 micrometers to about 0.1 micrometers. The smaller particles may provide better fluidity for printing the material34.

The material34may include bentonite, kaolinite clay, and/or any other suitable binder. In the exemplary embodiment, bentonite is used as a binder in the material34to provide increased adhesion and strength for the additively manufactured structure30.

The material34may also include a catalyst component and/or a dispersion solvent. For example and without limitation, the catalyst component may include zeolite socony mobil-5 (ZSM-5), porous carbon, silicon dioxide, metal oxide, and/or metal nanoparticles. For example and without limitation, the dispersion solvent may include distilled water and/or alcohol.

In some embodiments, the material34includes a plasticizer such as methylcellulose and/or a co-binder such as polyvinyl alcohol. In alternative embodiments, the material34may include any components that enable the material34to function as described herein.

In the exemplary embodiment, the additively manufactured structure30includes a first layer36, a second layer38, a third layer40, and a fourth layer42. In the illustrated embodiment, the additively manufactured structure30includes at least four layers each including the material34. In alternative embodiments, the additively manufactured structure30may include any layer that enables the additively manufactured structure to function as described herein. For example, in some embodiments, at least one layer32of the additively manufactured structure30includes a second material.

The layers32are arranged in a stacked configuration such that the material of each layer32is in contact with and adhered to the material of an adjacent layer(s)32(i.e., each layer32contacts a layer that is above or below the layer). In the exemplary embodiment, the layers32are adhered together such that the layers32are permanently joined together, i.e., the layers32cannot be separated without damaging the additively manufactured structure30. Accordingly, the additively manufactured structure30is a monolith and may be more durable than other structures that include separate components attached together. In addition, the additively manufactured structure30may be more compact than at least some known structures for reactionary processes.

The additively manufactured structure30is configured to provide a reaction when the additively manufactured structure30is exposed to at least one reactant. The reaction is caused by the active agent in the material34being exposed to a reactant. In the exemplary embodiment, the active agent of the additively manufactured structure30is in an unreduced state and includes a metal oxide, a group II metal carbonate, and/or a metal nanoparticle. The active agent is configured to provide a catalytic conversion of at least one reactant during the at least one reactionary process.

In some embodiments, the additively manufactured structure30is constructed for use in an adsorption process. For example, the additively manufactured structure30may be configured to receive a fluid flow including at least two gasses and process the fluid flow to remove at least one of the gasses. Specifically, the material34may be configured to absorb a first gas from the fluid flow. Accordingly, a second gas will be left in the fluid flow after reactions with the additively manufactured structure30. The first gas may be removed from the additively manufactured structure30by temperature control or any other suitable desorption process.

Each layer32of the additively manufactured structure30has a lattice or grid shape and defines a plurality of channels52extending through the thickness of the layer. For example, the first layer36includes ribs54extending longitudinally in the Z-direction and spaced apart in the X-direction to define the channels52therebetween. The second layer38includes ribs56extending longitudinally in the X-direction and spaced apart in the Z-direction to define the channels52therebetween. The channels52are in flow communication with each other and form a plurality of fluid flow paths for fluid to flow through the additively manufactured structure30. The fluid may include one or more reactants that interact with the material34as the fluid flows through the channels.

The grid patterns in adjacent layers32are offset such that the channels52define tortuous flow paths through the additively manufactured structure30. For example, in the illustrated embodiment, the grid pattern of the first layer36is offset from the grid pattern of the second layer38by 90°, i.e., the ribs54are perpendicular to the ribs56. The third, fifth, and seventh layers each include the same grid pattern as the first layer36. The fourth, sixth, and eighth layers each include the same grid pattern as the second layer38. Accordingly, the channels52are at least partly occluded by the ribs54,56in an adjacent layer32to form the tortuous flow paths. The tortuous flow paths may increase the contact between the reactants entrained in the fluid flow and the material34. In alternative embodiments, the layers32may have any patterns that enable the additively manufactured structure30to function as described herein. For example, in some embodiments, each layer32includes a plurality of cells or cells of unconventional geometric designs such as rhombohedral, trigonal, or open cellular configurations. For example,FIGS.18-21illustrate different configurations of additively manufactured structures300,302,304,306. The additively manufactured structure300shown inFIG.18includes at least 200 cells per square inch arranged in a grid pattern. The additively manufactured structure302shown inFIG.19includes an open geometric design with trigonal channels. The additively manufactured structure304shown inFIG.20includes at least 400 cells per square inch arranged in a grid pattern. The additively manufactured structure306shown inFIG.21includes at least 600 cells per square inch arranged in a grid pattern.

Referring toFIGS.1-3, in the illustrated embodiment, the additively manufactured structure30is a cylinder. The shape and size of the additively manufactured structure30may allow the additively manufactured structure to fit within an apparatus for a reactionary process such as in a conduit for fluid flow. The shape and size of the additively manufactured structure30may be precisely controlled and customized for specific applications because the additively manufactured structure30is fabricated using an additive manufacturing process which does not have the same design constraints as other methods to fabricate structures. In alternative embodiments, the additively manufactured structure30may have any shape that enables the multi-material structure to function as described herein.

FIG.4is a flow chart of an example method100of fabricating an additively manufactured structure such as the structure12(shown inFIG.1), the additively manufactured structure30(shown inFIG.2), and the multi-material structure200(shown inFIG.6). With reference toFIGS.1-4, the method100includes forming102an ink (e.g., the material34) from metal or metal oxide particles, a dispersion solvent, and a binder. For example, in some embodiments, the ink is formed by mixing the active agent in a solvent including the binder to form a paste.

The metal or metal oxide particles are configured to cause a reaction when exposed to a reactant. For example and without limitation, the metal or metal oxide particles may include copper oxide, chromium oxide, nickel oxide, titanium oxide, tungsten oxide, magnesium oxide (derived from calcined magnesium carbonate), calcium oxide (derived from calcined calcium carbonate), porous carbon, silicon dioxide, yttrium oxide, molybdenum oxide, zirconium oxide, zinc oxide, gallium oxide, vanadium oxide, niobium oxide, iron oxide, indium oxide, tin oxide, lanthanum oxide, copper nanoparticles, aluminum oxide, cerium oxide, manganese oxide, cobalt oxide, lead oxide, cadmium oxide, rhodium oxide, scandium oxide, technetium oxide, ruthenium oxide, rhenium oxide, tantalum oxide, germanium oxide, thallium oxide, iridium oxide, palladium nanoparticles, palladium oxide, gold nanoparticles, silver nanoparticles, silver oxide, platinum nanoparticles, barium oxide (derived from calcined barium carbonate), strontium oxide (calcined strontium carbonate), and/or beryllium oxide (derived from calcined beryllium carbonate). In some embodiments, the first material includes more than one metal.

The method100may allow for an increased oxide loading in the material because the metal or metal oxide particles are in the material during printing and are not formed by treating the structure after printing. For example, the structure may include a loading of the active agent in the material that is greater than 10%. In some embodiments, the loading of the active agent in the material is in a range of about 15% to about 85%.

The method100includes depositing104the ink onto a build platform (e.g., the build platform14). In some embodiments, the method100includes depositing two or more layers onto the build platform. The layers may be deposited in a desired shape such as a grid pattern on the build platform.

The method100includes curing106the ink to form a structure (e.g., the structure30) for use in a reactionary process. The cured structure includes the metal or metal oxide particles and is configured to provide a reaction when exposed to a reactant. The structure may be cured106by placing the structure in a controlled environment for a selected time. The temperature, pressure, moisture content and other environmental characteristics may be controlled during the curing process. In some embodiments, the method100includes heat treating the structure. Heat treating the structure may control the curing process for the ink. When the ink is cured, the structure may be a solid monolith structure. In addition or alternatively, heat treating the structure may provide a desired characteristic to the structure such as a hardness. In alternative embodiments, the structure may undergo any suitable treatment processes.

In some embodiments, the structure may be heated to calcine the binder in the ink. For example, the structure may be heated at a controlled rate to a selected temperature. The selected temperature may be equal to or greater than the calcination temperature of the binder. In some embodiments, the structure is heated in a two stage process to prevent collapse of the structure and/or burnout of the active agent in the material. For example, the structure may be heated to a first temperature and maintained isothermally at the first temperature for at least a selected time. After the selected time, the structure may be heated to a second temperature greater than the first temperature. The structure may be cured prior to heating to calcine the binder. When the ink is cured and the binder is calcined, the structure may be a solid monolith structure with an upper limit of metal or metal oxide loading of, for example, 85 percentage weight. The structure may include pores formed by the calcined binder.

In some embodiments, the structure is formed with metal particles and the structure is heated in an inert atmosphere instead of calcination to prevent reoxidation of the metal particles.

FIG.5is a flow chart of an example method108of using an additively manufactured structure such as the structure (shown inFIG.1), the additively manufactured structure30(shown inFIG.2), and the multi-material structure200(shown inFIG.6) in a reactionary process. With reference toFIGS.2,3, and5, the method108includes providing110an additively manufactured structure (e.g., the structure30) formed from a binder, a dispersion solvent, and an active agent. The active agent may include metal or metal oxide particles that are configured to provide a reaction when the additively manufactured structure is exposed to a reactant. For example, the active agent may include a metal oxide, a group II metal carbonate, and/or a metal nanoparticle.

The method108includes channeling112a fluid flow including at least one reactant through the structure such that the metal or metal oxide particles are exposed to the reactant. The metal or metal oxide particles cause a reaction when the fluid flow is directed through the structure. Accordingly, the method108can be used for reactionary processes including, for example and without limitation, carbon dioxide reduction, oxidative dehydrogenation of propane, n-hexane cracking, and methanol (MeOH) conversion to dimethyl ether (DME). The additively manufactured structure used in the method108may have a higher loading percentage of metal or metal oxide particles than other additively manufactured structures because the particles are directly printed in the additive manufacturing process. Also, the additively manufactured structures used in the method108may be resistant to deactivation (e.g., coking) and have a higher conversion rate and higher selectivity during the reactionary process than previous structures because the additively manufactured structures include the metal or metal oxide particles and are able to be precisely tuned for the reactions. In addition, the insoluble metal particles are suspended within the structure as opposed to formed them by impregnation and the suspended particles may enhance the contact between the heterogeneous active sites (i.e., ZSM-5 and the metal particles). As a result, retention of dentate compounds is reduced on the surface, thereby enhancing the stability of the catalyst and the reactant conversion and desired product selectivity.

FIG.6is a top view of a multi-material structure200formed using an additive manufacturing system.FIG.7is a perspective view of the multi-material structure200. The multi-material structure200includes a plurality of layers202and two or more different materials. Accordingly, the multi-material structure200is able to provide simultaneous reactions when exposed to at least one reactant. As a result, the multi-material structure200is configured for use in reactionary processes involving multiple reactions and is able to provide multiple reactions when the multi-material structure is exposed to one or more reactants.

The multi-material structure200includes a plurality of materials in a plurality of layers202. For example, the multi-material structure200includes a first layer204including a first material206formed from a first binder and a first active agent, and a second layer208including a second material210formed from a second binder and a second active agent. The first active agent and/or the second active agent may include metal or metal oxide particles. For example, the first active agent and/or the second active agent may comprise a metal oxide, a group II metal carbonate, and/or a metal nanoparticle.

In addition, the multi-material structure200includes a third layer212, a fourth layer214, a fifth layer216, a sixth layer218, a seventh layer220, and an eighth layer222. In the exemplary embodiment, each layer202includes the first material206or the second material210. Specifically, the materials206,210in the layers202are arranged in an alternating pattern (e.g., the first, third, fifth, and seventh layers include the first material206, and the second, fourth, sixth, and eighth layers include the second material210). In the illustrated embodiment, the multi-material structure200includes eight layers. In alternative embodiments, the multi-material structure200may include any layer that enables the multi-material structure to function as described herein. For example, in some embodiments, the multi-material structure200includes at least one layer including a third material formed from a third binder and a third active agent. In further embodiments, at least one of the layers202includes the first material206and the second material210.

The multi-material structure200is configured to provide multiple reactions when the multi-material structure200is exposed to at least one reactant. For example, the first material206has a first property that provides a first reaction during the at least one reactionary process. The first reaction is caused by the first active agent in the first material206being exposed to a reactant. For example, in some embodiments, the first agent is configured to absorb at least one reactant during the at least one reactionary process. In further embodiments, the first active agent is configured to provide a catalytic conversion of at least one reactant during the at least one reactionary process. In alternative embodiments, the first material206provides any reaction that enables the multi-material structure200to function as described herein.

The second material210has a second property that provides a second reaction during the at least one reactionary process. The second reaction is caused by the second active agent in the second material210being exposed to a reactant. For example, in some embodiments, the second agent is configured to absorb at least one reactant during the at least one reactionary process. In further embodiments, the second active agent is configured to provide a catalytic conversion of at least one reactant during at least one reactionary process.

In the exemplary embodiment, at least one of the first active agent and the second active agent includes metal or metal oxide particles that are configured to cause a reaction when exposed to a reactant. The particles are directly printed in the first material206and/or the second material210and the cured multi-material structure200includes the particles. The metal or metal oxide particles in the multi-material structure200are unreduced and are configured to cause a reaction when exposed to a reactant.

In some embodiments, the multi-material structure200is a photocatalyst and at least one of the first material206and the second material210is configured to interact with light. In alternative embodiments, the multi-material structure200provides any reaction that enables the multi-material structure200to function as described herein.

In further embodiments, the multi-material structure200is constructed for use in a multi-component adsorption process. For example, the multi-material structure200may be configured to receive a fluid flow including at least three gasses and process the fluid flow to remove at least two of the gasses. Specifically, the first material206may be configured to absorb a first gas from the fluid flow and the second material210may be configured to absorb a second gas from the fluid flow. Accordingly, a third gas will be left in the fluid flow after reactions with the multi-material structure200. The first and second gasses may be removed from the multi-material structure200by temperature control or any other suitable desorption process.

FIG.8is an enlarged view of a portion of a surface300of an example reactive structure302formed from a paste including metal or metal oxide particles. For example, the reactive structure includes gallium oxide particles. The surface300has a relatively even dispersion of crystalline phases because the metal or metal oxide particles are directly printed in the paste which causes the metal or metal oxide particles to be disbursed relatively evenly throughout the structure302. Moreover, the surface300of the structure302exhibits less clustering than structures formed using incipient impregnation. Additionally, the structure302provides enhanced catalytic activity during the reactionary process because accessibility of active sites in the structure302is increased in comparison to structures formed using incipient impregnation.

Example

In one embodiment, additively manufactured structures were formed using the additive manufacturing system10(shown inFIG.1). A first additively manufactured structure was fabricated using zeolite socony mobile-5 (ZSM-5) as a catalyst and gallium oxide (Ga2O3) as an active agent. A second additively manufactured structure was fabricated using ZSM-5 as a catalyst and zirconium oxide (ZrO) as an active agent. A third additively manufactured structure was fabricated using ZSM-5 as a catalyst and vanadium pentoxide (V2O5) as an active agent. A fourth additively manufactured structure was fabricated using ZSM-5 as a catalyst and chromium oxide (Cr2O3) as an active agent. A fifth additively manufactured structure was fabricated using ZSM-5 as a catalyst and gallium oxide, zirconium oxide, vanadium pentoxide, and chromium oxide as active agents. Initially, the ZSM-5 was activated. Binders and solvents were selected for each of the materials. For example, bentonite clay (BC) was used as an inorganic binder and methylcellulose (MC) was used as a plasticizing organic binder. Deionized (DI) water or DI water mixed with methanol (MeOH) was used as a solvent. Table 1 provides the weight and percentages for the binders, active agents, and catalyst for each additively manufactured structure.

TABLE 1Cr2O3Ga2O3V2O5ZrOH-ZSM-5BentoniteMethylcelluloseMonolith(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)ZSM-5/Ga150.012.70.00.072.012.72.5ZSM-5/Zr150.00.012.70.072.012.72.5ZSM-5/V150.00.00.012.772.012.72.5ZSM-5/Cr1512.70.00.00.072.012.72.5ZSM-5/MMO4.28.58.58.555.112.72.5

The catalyst (ZSM-5), active agents (Ga2O3, ZrO, V2O5, and Cr2O3), and binders (BC and MC) were dispersed into respective solvent mixtures to form a paste. For example, the components were mixed with distilled water inside of a polytetrafluoroethylene (PTFE) bottle until the powders dispersed and formed a paste. The pastes were then rolled at 20 rpm for 48 hours at 25° Celsius (C) to achieve binding. Additional solvent (e.g., about 3-5 drops of DI water) was mixed in the pastes to prepare the pastes for extrusion (e.g., provide proper fluidity of the pastes).

An additive manufacturing system (e.g., an aluminum prusa I3A pro 3D printer sold by Geetech Electronics Inc.) was used to form the structures. CAD software was used to design the monolith structures and a controller was used to read the generated CAD files and control operation of the printer. The pastes were loaded into separate syringes for extrusion. For example, about 3 to 10 cubic centimeters (cc) were loaded into each syringe. A piston head was placed into each syringe after the syringe was loaded with the paste. When the printer was ready to deposit each material onto the build platform, a pressurized air flow having a pressure in a range of 0-5 bar (depending on viscosity of the material) was supplied to the syringe to extrude the material through a 0.85 mm nozzle connected to the syringe.

The materials were deposited in a series of layers to form the desired height and shape of each structure. For example, a syringe was connected to the printer and used to deposit each layer of the material. The layers were formed with unit cells defining a plurality of apertures. Each layer included approximately 100 cells per square inch (cpsi). The completed structures each had a height of approximately 1.5 centimeters (cm).

The structures underwent heat treating to prevent cracking and improve strength. Specifically, the structures were dried at ambient temperature overnight at 25° C. and then heated to 750° C. for 6 hours to calcinate the structures. Once cooled, the composites were removed from the build platform and calcined to form monolithic structures including unreduced metal oxides. Accordingly, the samples provided unitary structures which were configured to provide desired reactions when the structures were exposed to a reactant.

The structures were used for a reactionary process including n-hexane cracking to determine reactive properties. Tables 2 and 3 show reactive properties of the structures. For example, the additively manufactured structures were activated with 150 mL/min air at 750° C. for 1 hour. The activated structures were exposed to 30 mL/min of hexane/N2fluid flow for 6 hours at temperatures of 550° C. (Table 2) and 600° C. (Table 3). An outlet product stream was analyzed every 30 min using a gas chromatograph, equipped with flame ionization and thermal conductivity detectors. The hexane conversion rates and the selectivity for products of the cracking reaction were determined for each structure, as shown in Tables 2 and 3.

TABLE 2HexaneProductMonolithConversion (%)ProductSelectivity (%)ZSM-5/Ga1545-49Methane17-20Ethane5-10Propane2Butane0C5+0BTX2-10Ethylene20-23Propylene28-29Butene3ZSM-5/V1530-31Methane32-65Ethane5-12Propane0Butane2-5C5+0BTX5-7Ethylene22-29Propylene9-15Butene1-3ZSM-5/Zr1545-49Methane12-29Ethane9-10Propane0-1Butane7C5+0BTX2-10Ethylene19-25Propylene29-30Butene3-4ZSM-5/Cr1579-85Methane10-23Ethane10-11Propane2-3Butane4-5C5+0BTX0Ethylene22-29Propylene38-40Butene3ZSM-5/MMO35-45Methane5-55Ethane4-5Propane0Butane5-11C5+0BTX2-3Ethylene10-30Propylene20-40Butene0

TABLE 3HexaneProductMonolithConversion (%)ProductSelectivity (%)ZSM-5/Ga1560-62Methane18Ethane8Propane0Butane5C5+0BTX14-15Ethylene28-29Propylene24-25Butene3ZSM-5/V1519-25Methane18-19Ethane9-10Propane0-1Butane14-15C5+0-3BTX0Ethylene33Propylene20-21Butene0-1ZSM-5/Zr1549-58Methane12-15Ethane5-9Propane0-2Butane3-5C5+0BTX9-15Ethylene25-31Propylene24-29Butene2-3ZSM-5/Cr1551-52Methane19-21Ethane8-9Propane0-1Butane5C5+0-1BTX5-8Ethylene27-29Propylene29-30Butene3-5ZSM-5/MMO38-49Methane20-24Ethane10-11Propane0Butane0-5C5+0BTX0-3Ethylene28-33Propylene25-27Butene3-4s

Table 4 (below) provides the turnover frequency (TOF) and the hexane reaction rate per catalyst surface area. The TOF was calculated using Equation (1).

TOF=nc⁢⁢6⁢H14×Hexane⁢⁢Conversion×Migcatalyst×XiEquation⁢⁢(1)

where nc3H14is the molar flow rate of hexane, Miis the catalyst molecular weight, and Xiis the weight fraction of the catalyst in the printed monolith.

The hexane reaction rate per catalyst surface area was calculated using Equation (2).

QC⁢6⁢H⁢1⁢4=1⁢01325⁢⁢Pa×0.21×30⁢⁢mLmin8.3⁢14⁢⁢kg×m2K×mol×s2×1000⁢⁢mLm⁢3Equation⁢⁢(2)Rate=QC⁢3⁢H⁢8×Hexane⁢⁢Conversion×gcatalystSB⁢E⁢TEquation⁢⁢(3)

where the molar flowrate of hexane (Qc6H14, mol/min) was derived from the ideal gas law, SBETis the catalyst surface area from N2physisorption, and gcatalystis the weight of the sample used in each reaction.

TABLE 4Reaction Rate × 103TemperatureTOF(mol C6H14/Monolith(° C.)(s−1)min · m2cat.)ZSM-5/Ga155505.382.46004.763.0ZSM-5/V155509.1147.760012.4338.5ZSM-5/Zr155508.682.460011.582.8ZSM-5/Cr1555016.554.760011.172.9ZSM-5/MMO5506.309.96006.4610.8

The additively manufactured structures provide examples of customizable heterogeneous catalysts. The additively manufactured structures in the example provided high conversion rates and high selectivity for hexane cracking. Moreover, the additively manufactured structures may be produced at scale using additive manufacturing processes.

Example

In one embodiment, additively manufactured structures were formed using the additive manufacturing system10(shown inFIG.1). A first additively manufactured structure was fabricated using zeolite socony mobile-5 (ZSM-5) as a catalyst and gallium oxide (Ga2O3) and zirconium oxide (ZrO) as active agents. A second additively manufactured structure was fabricated using ZSM-5 as a catalyst and gallium oxide and vanadium pentoxide (V2O5) as active agents. A third additively manufactured structure was fabricated using ZSM-5 as a catalyst and zirconium oxide and gallium oxide as active agents. A fourth additively manufactured structure was fabricated using ZSM-5 as a catalyst and gallium oxide, zirconium oxide, and vanadium pentoxide as active agents. Initially, the ZSM-5 was activated. Binders and solvents were selected for each of the materials. For example, bentonite clay (BC) was used as an inorganic binder and methylcellulose (MC) was used as a plasticizing organic binder. Deionized (DI) water or DI water mixed with methanol (MeOH) was used as a solvent. Table 5 provides the weight and percentages for the binders, active agents, and catalyst for each additively manufactured structure.

TABLE 5Ga2O3V2O5ZrOH-ZSM-5BentoniteMethylcelluloseMonolith(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)ZSM-5/Ga15/Zr1512.30.012.358.215.12.1ZSM-5/V15/Ga1512.312.30.058.215.12.1ZSM-5/Zr15/Ga150.012.312.358.215.12.1ZSM-5/Ga10/Zr15/V158.28.28.258.215.12.1

The catalyst (ZSM-5), active agents (Ga2O3, ZrO, and V2O5), and binders (BC and MC) were dispersed into respective solvent mixtures to form a paste. For example, the components were mixed with distilled water inside of a polytetrafluoroethylene (PTFE) bottle until the powders dispersed and formed a paste. The mixtures were then rolled at 20 rpm for 48 hours at 25° Celsius (C) to achieve binding. The mixtures were densified at 50° C. and 300 rpm to generate pastes.

An additive manufacturing system (e.g., an aluminum prusa I3A pro 3D printer sold by Geetech Electronics Inc.) was used to form the structures. CAD software was used to design the monolith structures and a controller was used to read the generated CAD files and control operation of the printer. The pastes were loaded into separate syringes for extrusion. For example, about 3 to 10 cubic centimeters (cc) were loaded into each syringe. A piston head was placed into each syringe after the syringe was loaded with the paste. When the printer was ready to deposit each material onto the build platform, a pressurized air flow having a pressure in a range of 0-5 bar (depending on viscosity of the material) was supplied to the syringe to extrude the material through a 0.85 mm nozzle connected to the syringe.

The materials were deposited in a series of layers to form the desired height and shape of each structure. For example, a syringe was connected to the printer and used to deposit each layer of the material. The layers were formed with unit cells defining a plurality of apertures. Each layer included approximately 100 cells per square inch (cpsi). The completed structures each had a height of approximately 1.5 centimeters (cm).

The structures underwent heat treating to prevent cracking and improve strength. Specifically, the structures were dried at ambient temperature overnight at 25° C. and then heated to 750° C. for 6 hours to calcinate the structure and burn out the methylcellulose. Once cooled and dried, the composites were removed from the build platform and calcined to form a monolithic structure including unreduced metal oxide. Accordingly, the samples provided unitary structures which were configured to provide desired reactions when the structures were exposed to a reactant.

The structures were used for a reactionary process including an oxidative dehydrogenation of propane (ODHP) reaction. For example, the additively manufactured structures were activated with 150 mL/min air at 750° C. for 1 hour. The activated structures were exposed to 60 mL/min of feed gas fluid flow for 6 hours at temperatures of 550° C. The feed gas included 2.5 mol % propane and 5 mol % of carbon dioxide balanced with dinitrogen. An outlet product stream was analyzed every 30 min using a gas chromatograph, equipped with flame ionization and thermal conductivity detectors. The reactive properties for oxidative dehydrogenation of propane were determined for each structure. Table 6 shows reactive properties of the reactive structures.

TABLE 6C3H8CO2C3H6C2H4CH4ReactionConversionConversionSelectivitySelectivitySelectivityTOFRate × 105Monolith(%)(%)(%)(%)(%)(s−1)(kmol/gcats)ZSM-5/Ga15/Zr1536.746.588.26.35.50.0114.6ZSM-5/V15/Ga1538.848.758.926.614.50.0165.1ZSM-5/Zr15/Ga1537.748.289.55.15.40.0144.8ZSM-5/Ga10/Zr10/V1037.247.785.98.06.10.0134.7

The additively manufactured structures in the example provided high conversion rates and high selectivity for catalytic reactions. Accordingly, the additively manufactured structures provide examples of customizable heterogeneous catalysts.

Example

In one embodiment, additively manufactured structures were formed using the additive manufacturing system10(shown inFIG.1). A first additively manufactured structure was fabricated using zeolite socony mobile-5 (ZSM-5) as a catalyst and gallium oxide (Ga2O3) as an active agent. A second additively manufactured structure was fabricated using ZSM-5 as a catalyst and vanadium pentoxide (V2O5) as an active agent. A third additively manufactured structure was fabricated using ZSM-5 as a catalyst and zirconium oxide as an active agent. A fourth additively manufactured structure was fabricated using ZSM-5 as a catalyst and chromium oxide (Cr2O3) as an active agent. A fifth additively manufactured structure was fabricated using ZSM-5 as a catalyst and gallium oxide, zirconium oxide, and vanadium pentoxide as active agents. In addition, a sixth structure was fabricated using H-ZSM-5 without a separate active agent. Initially, the ZSM-5 was activated. Binders and solvents were selected for each of the materials. For example, bentonite clay (BC) was used as an inorganic binder and methylcellulose (MC) was used as a plasticizing organic binder. Deionized (DI) water or DI water mixed with methanol (MeOH) was used as a solvent. Table 7 provides the weight and percentages for the binders, active agents, and catalyst for each additively manufactured structure.

TABLE 7Cr2O3Ga2O3V2O5ZrOH-ZSM-5BentoniteMethylcelluloseMonolith(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)ZSM-5/Ga150.012.70.00.072.012.72.5ZSM-5/V150.00.012.70.072.012.72.5ZSM-5/Zr150.00.00.012.772.012.72.5ZSM-5/Cr1512.70.00.00.072.012.72.5ZSM-5/Ga10/Zr10/V104.28.58.58.555.112.72.5H-ZSM-50.00.00.00.082.514.52.9

The catalyst (ZSM-5), active agents (Cr2O3, Ga2O3, ZrO, and V2O5), and binders (BC and MC) were dispersed into respective solvent mixtures to form a paste. For example, the components were mixed with distilled water inside of a polytetrafluoroethylene (PTFE) bottle until the powders dispersed and formed a paste. The pastes were then rolled at 20 rpm for 48 hours at 25° Celsius (C) to achieve binding.

An additive manufacturing system (e.g., an aluminum prusa I3A pro 3D printer sold by Geetech Electronics Inc.) was used to form the structures. CAD software was used to design the monolith structures and a controller was used to read the generated CAD files and control operation of the printer. The pastes were loaded into separate syringes for extrusion. For example, about 3 to 10 cubic centimeters (cc) were loaded into each syringe. A piston head was placed into each syringe after the syringe was loaded with the paste. When the printer was ready to deposit each material onto the build platform, a pressurized air flow having a pressure in a range of 0-5 bar (depending on viscosity of the material) was supplied to the syringe to extrude the material through a 0.85 mm nozzle connected to the syringe.

The materials were deposited in a series of layers to form the desired height and shape of each structure. For example, a syringe was connected to the printer and used to deposit each layer of the material. The layers were formed with unit cells defining a plurality of apertures. Each layer included approximately 100 cells per square inch (cpsi). The completed structures each had a height of approximately 1.5 centimeters (cm).

The structures underwent heat treating to prevent cracking and improve strength. Specifically, the structures were dried at ambient temperature overnight at 25° C. and then heated to 750° C. for 6 hours to calcinate the structure and burn out the methylcellulose. Once cooled and dry, the composites were removed from the build platform and calcined to form monolithic structures including unreduced metal oxide. Accordingly, the samples provided unitary structures which were configured to provide desired reactions when the structures were exposed to a reactant.

The structures were used for a reactionary process including carbon dioxide reduction in tandem with oxidative dehydrogenation of propane (ODHP). For example, the additively manufactured structures were activated with 150 mL/min air at 750° C. for 1 hour. The activated structures were exposed to 60 mL/min of feed gas fluid flow for 6 hours at temperatures of 550° C. The feed gas included 2.5 mol % propane and 5 mol % of carbon dioxide balanced with dinitrogen. An outlet product stream was analyzed every 30 min using a gas chromatograph, equipped with flame ionization and thermal conductivity detectors. The conversion rates and the selectivity for products of the reaction were determined for each structure, as shown in Table 8.

TABLE 8C3H8CO2ProductConversionConversionSelectivityTOFReaction Rate × 103Monolith(%)(%)Product(%)(s−1)(molC3H6min−1m−2cat.)ZSM-5/Ga153760-70Propylene570.0108.1Ethene25Methane18BTX0ZSM-5/V1538-4048Propylene810.01111.8Ethene18Methane1BTX0ZSM-5/Zr153545-50Propylene960.010435.7Ethene4Methane0BTX0ZSM-5/Cr1536-4050Propylene850.01115.1Ethene6Methane9BTX0ZSM-5/3950Propylene95-970.00962.6Ga10/Zr10/V10Ethene3-5Methane0-2BTX0H-ZSM-520-3035Propylene25-500.00879.6Ethene15-25Methane25-60BTX0

The propane conversion, the CO2conversion, and the hydrocarbon (HC) selectivity were calculated using Equations (4), (5), and (6), respectively.

Propane⁢⁢conversion⁢⁢(%)=C3⁢H8i⁢⁢n-C3⁢H8outC3⁢H8i⁢⁢n×100Equation⁢⁢(4)CO2⁢⁢conversion⁢⁢(%)=CO2i⁢⁢n-CO2outCO2i⁢⁢n×100Equation⁢⁢(5)HC⁢⁢selectivity⁢⁢(%)=HCoutC3⁢H6out+CH4out+C2⁢H4out+BTXoutEquation⁢⁢(6)
where HCoutrefers to desired hydrocarbon molar flow in the outlet stream, C3H8inrefers to propane molar flow in the inlet stream, C3H8outrefers to propane molar flow in the outlet stream, CO2inrefers to carbon dioxide molar flow in the inlet stream, CO2outrefers to carbon dioxide molar flow in the outlet stream, C3H6outrefers to methyl ethylene molar flow in the outlet stream, CH4outrefers to methane molar flow in in outlet stream, C2H4outrefers to acetylene in the outlet stream, and BTXoutrefers to benzene toulene exlylene mixture in the outlet stream. All of the parameters in the equations were in molar flow rate of the individual compounds. The monolith's average molecular weights were considered to be the weighted average of the individual component's molecular weights based on their calcined fractions.

Table 8 also provides the turnover frequency (TOF) and the reaction rate per catalyst surface area. The TOF was calculated using Equation (7).

TOF=nc⁢3⁢H⁢8×Propane⁢⁢Conversion×Migcatalyst×XiEquation⁢⁢(7)

where nc3H8is the molar flow rate of propane, Miis the catalyst molecular weight, and Xiis the weight fraction of the catalyst in the printed monolith.

The reaction rate per catalyst surface area was calculated using Equations (8) and (9).

QC⁢3⁢H⁢8=1⁢01325⁢⁢Pa×0.025×60⁢⁢mLmin8.3⁢14⁢⁢kg×m2K×mol×s2Equation⁢⁢(8)Rate=QC⁢3⁢H⁢8×Propane⁢⁢Conversion×C⁢⁢3⁢H⁢⁢6⁢⁢Selectivity×gcatalystSBET×1⁢0⁢0⁢0⁢0Equation⁢⁢(9)

where the molar flowrate of propane (Qc3H8, mol/min) was derived from the ideal gas law, SBETis the catalyst surface area from N2physisorption, and gcatalystis the weight of the sample used in each reaction.

The additively manufactured structures in the example provided high conversion rates and high selectivity for catalytic reactions. In addition, the additively manufactured structures experienced little to no coking. In contrast, catalysts formed by incipient impregnation can experience significant coking which effects the reaction processes that the catalyst are used for. Accordingly, in contrast to catalyst formed by incipient impregnation, the described additively manufactured structures are precisely customizable within a larger range of potential oxide loadings and provide more efficient catalytic reactions.

Example

In one embodiment, additively manufactured structures were formed using the additive manufacturing system10(shown inFIG.1). A first additively manufactured structure was fabricated using zeolite socony mobile-5 (ZSM-5) as a catalyst without an active agent. A second additively manufactured structure was fabricated using ZSM-5 as a catalyst and gallium oxide (Ga2O3) as an active agent. A third additively manufactured structure was fabricated using ZSM-5 as a catalyst and gallium oxide and zirconium oxide (ZrO) as active agents. A fourth additively manufactured structure was fabricated using ZSM-5 as a catalyst and gallium oxide and vanadium pentoxide (V2O5) as active agents. Initially, the ZSM-5 was activated. Binders and solvents were selected for each of the materials. For example, bentonite clay (BC) was used as an inorganic binder and methylcellulose (MC) was used as a plasticizing organic binder. Deionized (DI) water or DI water mixed with methanol (MeOH) was used as a solvent. Table 9 provides the weight and percentages for the binders, active agents, and catalyst for each additively manufactured structure.

TABLE 9Ga2O3ZrO2V2O5H-ZSM-5BentoniteMethylcelluloseMonolith(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)ZSM-500084.812.72.5ZSM-5/Ga43.40081.412.72.5ZSM-5/Ga4/Zr43.43.407812.72.5ZSM-5/Ga4/V43.403.47812.72.5

The catalyst (ZSM-5), active agents (Ga2O3, ZrO, V2O5, and Cr2O3), and binders (BC and MC) were dispersed into respective solvent mixtures to form a paste. For example, the components were mixed with distilled water inside of a polytetrafluoroethylene (PTFE) bottle until the powders dispersed and formed a paste. The pastes were then rolled at 20 rpm for 48 hours at 25° Celsius (C) to achieve binding. Additional solvent (e.g., about 3-5 drops of DI water) was mixed in the pastes to prepare the pastes for extrusion (e.g., provide proper fluidity of the pastes).

An additive manufacturing system (e.g., an aluminum prusa I3A pro 3D printer sold by Geetech Electronics Inc.) was used to form the structures. CAD software was used to design the monolith structures and a controller was used to read the generated CAD files and control operation of the printer. The pastes were loaded into syringes for extrusion. For example, about 3 to 10 cubic centimeters (cc) were loaded into each syringe. A piston head was placed into each syringe after the syringe was loaded with the paste. When the printer was ready to deposit each material onto the build platform, a pressurized air flow having a pressure in a range of 0-5 bar (depending on viscosity of the material) was supplied to the syringe to extrude the material through a 0.85 mm nozzle connected to the syringe.

The materials were deposited in a series of layers to form the desired height and shape of each structure. For example, a syringe was connected to the printer and used to deposit each layer of the material. The layers were formed with unit cells defining a plurality of apertures. Each layer included approximately 100 cells per square inch (cpsi). The completed structures each had a height of approximately 1.5 centimeters (cm).

The structures underwent heat treating to prevent cracking and improve strength. Specifically, the structures were dried at ambient temperature overnight at 25° C. and then heated to 550° C. for 6 hours to calcinate the structure. Once cooled and dry, the composites were removed from the build platform and calcined to form monolithic structures including unreduced metal oxide. Accordingly, the samples provided unitary structures which were configured to provide desired reactions when the structures were exposed to a reactant.

The structures were used for a reactionary process including methanol (MeOH) conversion to dimethyl ether (DME). Table 10 shows reactive properties of the reactive structures. For example, the additively manufactured structures were pretreated with 30 mL/min air at 500° C. for 2 hours. The structures were then exposed to 30 mL/min of N2fluid flow for 5 hours at temperatures of 200° C., 300° C. and 400° C. An outlet product stream was analyzed every 30 min using a gas chromatograph, equipped with a flame ionization detector. The reactive properties for a reactionary process including methanol conversion to dimethyl ether were determined for each structure, as shown in Table 10.

TABLE 10ReactionReaction Rate × 103TemperatureMeOHDME(molDME/Sample(° C.)ConversionSelectivitymin · m2catalyst)ZSM-520069.280.67.330081.125.02.740086.820.02.3Ga4/20085.273.99.6ZSM-530090.539.05.440096.538.65.7Ga4—Zr4/20081.925.03.3ZSM-530084.124.63.440071.41.10.1Ga4—V4/20081.432.34.9ZSM-530082.530.34.740062.72.90.3

The reaction rates per catalyst surface area were calculated by Equation 10:

Rate=WHSV×MeOH⁢⁢Conversion×DME⁢⁢Selectivity×60⁢⁢min×1⁢⁢mol⁢⁢MeOH10,000×SBET×1⁢⁢h×32.04⁢⁢gMeOHEquation⁢⁢(10)

where WHSV is the weight hour space velocity, and SBETis the monoliths' surface areas gathered from N2physisorption.

The additively manufactured structures provided high conversion rates and high selectivity for the tested reactionary processes. In addition, the structures had a stability and were resistant to deactivation. For example, the structures did not experience coking even when exposed for 6 hours.

Example

In one embodiment, additively manufactured structures were formed using the additive manufacturing system10(shown inFIG.1). A first additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts without an active agent. A second additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and In2O3as an active agent. A third additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and CeO2as an active agent. A fourth additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and MoO3as an active agent. A fifth additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and Cr2O3as an active agent. Initially, the ZSM-5 and CaO derived from calcined CaCO3were activated. Binders and solvents were selected for each of the materials. For example, bentonite clay (BC) was used as an inorganic binder and methylcellulose (MC) was used as a plasticizing organic binder. Deionized (DI) water or DI water mixed with methanol (MeOH) was used as a solvent. Table 11 provides the weight and percentages for the binders, active agents, and catalyst for each additively manufactured structure.

TABLE 11BentoniteMethyl-ZSM-5CaCO3ClaycelluloseIn2O3CeO2MoO3Cr2O3Sample(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)CaO—29.059.010.02.00.00.00.00.0ZSM-5CaO—In@27.455.59.11.96.10.00.00.0ZSM-5CaO—Ce@27.455.59.11.90.06.10.00.0ZSM-5CaO—Mo@27.455.59.11.90.00.06.10.0ZSM-5CaO—Cr@27.455.59.11.90.00.00.06.1ZSM-5

The catalyst (CaCO3and ZSM-5), active agents (In2O3, CeO2, MbO3, and Cr2O3), and binders (BC and MC) were dispersed into respective solvent mixtures to form a paste. For example, the components were mixed with distilled water inside of a polytetrafluoroethylene (PTFE) bottle until the powders dispersed and formed a paste. The pastes were then rolled at 60 rpm for 48 hours at 25° Celsius (C) to achieve binding. Additional solvent (e.g., about 3-5 drops of DI water) was mixed in the pastes to prepare the pastes for extrusion (e.g., provide proper fluidity of the pastes).

An additive manufacturing system (e.g., an aluminum prusa I3A pro 3D printer sold by Geetech Electronics Inc.) was used to form the structures. CAD software was used to design the monolith structures and a controller was used to read the generated CAD files and control operation of the printer. The pastes were loaded into syringes for extrusion. For example, about 3 to 10 cubic centimeters (cc) were loaded into each syringe. A piston head was placed into each syringe after the syringe was loaded with the paste. When the printer was ready to deposit each material onto the build platform, a pressurized air flow having a pressure in a range of 0-5 bar (depending on viscosity of the material) was supplied to the syringe to extrude the material through a 0.85 mm nozzle connected to the syringe.

The materials were deposited in a series of layers to form the desired height and shape of each structure. For example, a syringe was connected to the printer and used to deposit each layer of the material. The layers were formed with unit cells defining a plurality of apertures. Each layer included approximately 100 cells per square inch (cpsi). The completed structures each had a height of approximately 1.5 centimeters (cm).

The structures underwent heat treating to prevent cracking and improve strength. Specifically, the structures were dried at ambient temperature for 12 hours at 25° C. and then heated to 550° C. for 6 hours to calcinate the structure. Once cooled and dried, the composites were removed from the build platform and calcined to form monolithic structures including unreduced metal oxide. Accordingly, the samples provided unitary structures which were configured to provide desired reactions when the structures were exposed to a reactant.

The structures were used for a reactionary process including adsorption and catalytic conversion reactions.FIGS.9-14and Table 12 show reactive properties of the reactive structures. For example, the additively manufactured structures were exposed to 20 mL/min of Ar and heated at 10° C./min to 700° C. under gas for hour to desorb CO2and activate the CaO adsorbent. Next, the environment of the additively manufactured structures was cooled to 600° C. and 20 mL/min of 10% CO2/Ar was allowed to flow into the system for 1 h to saturate the adsorbent phase upon reaching the target temperature. Then, the system was heated at 10° C./min to the desired reaction temperature (600, 650 or 700° C.) while maintaining a flow of CO2. Once reaching the desired temperature, the flow of CO2was terminated and 20 mL/min of 5% C3H8/Ar was delivered into the reactor. The concentration profiles of the species were collected with an MKS Cirrus II Mass Spectrometer throughout the entirety of the experiment, and the CO2adsorption capacities of the different samples were assessed with thermogravimetric analysis (TGA) on a Q500 thermogravimetric gas analyzer (TGA). Therein, the samples were heated at 10° C./min to 750° C. with exposure to 40 mL/min of N2to remove CO2from the CaO phase. After 1 h, the system was cooled to 600° C. and 60 mL/min of 10% CO2/N2was passed over the sample for 90 min.

FIGS.9-14illustrate the adsorption and catalysis results for the additively manufactured structures. Specifically,FIG.9is a bar graph indicating the CO2adsorption capacities of the additively manufactured structures. The additively manufactured structures displayed adsorption capacities of 5.0-5.2, signifying that there were minimal effects from the metal dopants on the affinity for CO2. The additively manufactured structures displayed higher propane conversion but reduced CO2conversion and propylene yield as the temperature was increased. Also, the additively manufactured structures demonstrated that combined adsorption/catalysis for ODHP can occur solely at 600° C. Performing ODHP over the additively manufactured structures reduces or eliminates the adsorption and catalysis thermal swing, and, thereby, enhances process output and lowers the energy requirement for the reactions.

Regarding the actual propylene yields, the results inFIGS.10-14indicate that selection of the metal dopant is important for optimizing the ODHP behavior, but is of lesser importance compared to the effects on product selectivity. For example, the undoped sample (FIG.10) displayed the highest CO2conversion at 600° C., but also generated the lowest propylene yield (i.e., 15%). In contrast, at the same temperature the metal-doped samples all displayed some degree of enhancement in both propane conversion and propylene yield. Specifically, the highest propylene yields were observed in CaO—In@ZSM-5 (FIG.11), CaO—Mo@ZSM-5 (FIG.13), and CaO—Cr@ZSM-5 (FIG.14) which achieved 22%, 20.4%, and 24% yields, respectively. For example, CaO—Mo@ZSM-5 provided a good balance of CO2conversion and propylene yield for dual-functional CO2adsorption and ODHP catalysis. As seen inFIGS.9-14, the additively manufactured structures are viable dual-functional materials (DFMs) and provided reactions, for example, where propylene was generated whilst CO2was consumed.

In addition, the selectivity for products of the reaction were determined for each structure, as shown in Table 12.

TABLE 12ReactionC3H6C2H4CH4COH2H2OTemperatureSelectivitySelectivitySelectivitySelectivitySelectivitySelectivitySample(° C.)(%)(%)(%)(%)(%)(%)CaO—60036.70.018.426.47.511.0ZSM-565013.221.615.615.825.18.77006.2326.521.720.621.14.0CaO—In@60040.70.112.723.55.517.6ZSM-565023.713.312.027.120.83.270014.228.426.48.817.44.9CaO—Ce@60037.22.218.413.911.416.8ZSM-565031.81.721.619.98.716.37009.923.421.721.619.93.6CaO—Mo@60028.30.117.422.83.228.3ZSM-565012.323.319.819.222.82.67006.324.020.026.220.33.2CaO—Cr@60034.52.112.224.613.612.7ZSM-565015.616.917.619.723.27.070010.625.720.217.821.74.1

In addition, the structures were used for a reactionary process including adsorption of CO2and for oxidative dehydrogenation of ethane (ODHE). For example, the additively manufactured structures were exposed to 40 mL/min of N2and heated at 10° C./min to 750° C. for 1 hour. Next, the environment of the additively manufactured structures was cooled to 600° C. and 60 mL/min of 10% CO2/N2was allowed to flow into the system for 90 minutes to saturate the adsorbent phase. To determine ODHE properties, the additively manufactured structures were exposed to 40 mL/min of Ar and heated at 10° C./min to 750° C. for 1 hour. Next, the environment of the additively manufactured structures was cooled to 600° C. and 25 mL/min of 10% CO2/Ar was allowed to flow into the system for 1 h. Then, the system was heated at 10° C./min to the desired reaction temperature 700° C. while maintaining a flow of CO2/Ar. Upon reaching the desired temperature, the flow of CO2was terminated and 25 mL/min of 7% C2H6/Ar was delivered into the reactor. The concentration profiles of the species were collected with an MKS Cirrus II Mass Spectrometer throughout the entirety of the experiment, and the CO2adsorption capacities of the different samples were assessed with thermogravimetric analysis (TGA) on a Q500 thermogravimetric gas analyzer (TGA).

FIG.15and Table 13 show reactive properties of the additively manufactured structures. Specifically,FIG.15is a bar graph indicating the CO2adsorption capacities of the additively manufactured structures. Table 13 includes the CO2adsorbed, CO2conversion, C2H6conversion, the C2H4selectivity, and the C2H4yield.

TABLE 13CO2CO2C2H6C2H4C2H4adsorbedConversionConversionSelectivityYieldSample(mmol/g)(%)(%)(%)(%)CaO—1.327.134.379.827.4ZSM-5CaO—Ce/1.333.733.298.532.7ZSM-5CaO—Mo/1.722.634.989.431.2ZSM-5CaO—Cr/1.056.037.191.233.8ZSM-5CaO—In/1.518.230.791.628.1ZSM-5

The additively manufactured structures provided high conversion rates and high selectivity for the tested reactionary processes.

Example

In one embodiment, additively manufactured structures were formed using the additive manufacturing system10(shown inFIG.1). A first additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts without an active agent. A second additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and V2O5as an active agent. A third additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and Ga2O3as an active agent. A fourth additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and TiO2as an active agent. A fifth additively manufactured structure was fabricated using CaO derived from calcined CaCO3and ZSM-5 as catalysts and NiO as an active agent. Initially, the ZSM-5 and CaO3were activated. Binders and solvents were selected for each of the materials. For example, bentonite clay (BC) was used as an inorganic binder and methylcellulose (MC) was used as a plasticizing organic binder. Deionized (DI) water or DI water mixed with methanol (MeOH) was used as a solvent. Table 14 provides the weight and percentages for the binders, active agents, and catalyst for each additively manufactured structure.

TABLE 14BentoniteMethyl-ZSM-5CaCO3ClaycelluloseV2O5Ga2O3TiO2NiOSample(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)(wt. %)CaO—29.059.010.02.00.00.00.00.0ZSM-5CaO—V/27.455.59.11.96.10.00.00.0ZSM-5CaO—GA/27.455.59.11.90.06.10.00.0ZSM-5CaO—Ti/27.455.59.11.90.00.06.10.0ZSM-5CaO—Ni/27.455.59.11.90.00.00.06.1ZSM-5

The catalyst (CaCO3and ZSM-5), active agents (V2O5, Ga2O3, TiO2, and NiO), and binders (BC and MC) were dispersed into respective solvent mixtures to form a paste. For example, the components were mixed with distilled water inside of a polytetrafluoroethylene (PTFE) bottle until the powders dispersed and formed a paste. The pastes were then rolled at 60 rpm for 48 hours at 25° Celsius (C) to achieve binding. The pastes were heated at 60° C. for 4 hours to extract water and obtain a self-standing rheology. As used herein, self-standing rheology refers to a material which retains layer separation after printing without fluidic spreading.

An additive manufacturing system (e.g., an aluminum prusa I3A pro 3D printer sold by Geetech Electronics Inc.) was used to form the structures. CAD software was used to design the monolith structures and a controller was used to read the generated CAD files and control operation of the printer. The pastes were loaded into syringes for extrusion. For example, about 3 to 10 cubic centimeters (cc) were loaded into each syringe. A piston head was placed into each syringe after the syringe was loaded with the paste. When the printer was ready to deposit each material onto the build platform, a pressurized air flow having a pressure in a range of 0-5 bar (depending on viscosity of the material) was supplied to the syringe to extrude the material through a 0.85 mm nozzle connected to the syringe.

The materials were deposited in a series of layers to form the desired height and shape of each structure. For example, a syringe was connected to the printer and used to deposit each layer of the material.

The structures underwent heat treating to prevent cracking and improve strength. Specifically, the structures were dried at ambient temperature for 12 hours at 25° C. and then heated to 550° C. for 6 hours to calcinate the structure. Once cooled and dried, the composites were removed from the build platform and calcined to form monolithic structures including unreduced metal oxide. Accordingly, the samples provided unitary structures which were configured to provide desired reactions when the structures were exposed to a reactant.

The structures were used for a reactionary process including adsorption of CO2. For example, the additively manufactured structures were exposed to 20 mL/min of N2and heated at 10° C./min to 750° C. for 1 hour. Next, the environment of the additively manufactured structures was cooled to 600° C. and 60 mL/min of 10% CO2/N2was allowed to flow into the system for 1 h to saturate the adsorbent phase. To prepare for the adsorption/catalysis experiments, the additively manufactured structures were exposed to 20 mL/min of Ar and heated at 10° C./min to 700° C. for 1 hour. Next, the environment of the additively manufactured structures was cooled to 600° C. and 20 mL/min of 10% CO2/Ar was allowed to flow into the system for 1 h. Then, the system was heated at 10° C./min to the desired reaction temperature (600, 650 or 700° C.) while maintaining a flow of CO2. Upon reaching the desired temperature, the flow of CO2was terminated and 20 mL/min of 5% C3H8/Ar was delivered into the reactor. The concentration profiles of the species were collected with an MKS Cirrus II Mass Spectrometer throughout the entirety of the experiment, and the CO2adsorption capacities of the different samples were assessed with thermogravimetric analysis (TGA) on a Q500 thermogravimetric gas analyzer (TGA).

FIG.16and Table 15 show reactive properties of the additively manufactured structures. Specifically,FIG.15is a bar graph indicating the CO2adsorption capacities of the additively manufactured structures. Table 14 includes the C3H8conversion, CO2conversion, C3H6yield, and the selectivity for products of the reaction for each of the additively manufactured structures at the tested temperatures.

TABLE 15ReactionC3H8CO2C3H6C3H6C2H4CH4COH2H2OTemperatureConversionConversionYieldSelectivitySelectivitySelectivitySelectivitySelectivitySelectivitySample(° C.)(%)(%)(%)(%)(%)(%)(%)(%)(%)CaO—60019.178.116.336.70.018.426.47.511.0ZSM-565029.462.319.313.221.615.615.825.18.770036.057.523.26.2326.521.720.621.14.0CaO—V/60025.665.622.825.20.112.723.55.517.6ZSM-565036.460.32416.313.312.027.120.83.270041.555.2268.928.426.48.817.44.9CaO—Ni/60024.271.217.89.72.218.413.911.416.8ZSM-565028.860.020.35.81.721.619.98.716.370039.133.320.23.823.421.721.619.93.6CaO—Ti/60023.175.719.039.00.117.422.83.228.3ZSM-565032.467.621.919.823.319.819.222.82.670036.556.723.67.524.020.026.220.33.2CaO—Ga/60025.570.223.042.02.112.224.613.612.7ZSM-565030.860.724.422.516.917.619.723.27.070037.258.625.37.025.720.217.821.74.1

In addition, the structures were used for a reactionary process including adsorption of CO2and for oxidative dehydrogenation of ethane (ODHE). For example, the additively manufactured structures were exposed to 40 mL/min of N2and heated at 10° C./min to 750° C. for 1 hour. Next, the environment of the additively manufactured structures was cooled to 600° C. and 60 mL/min of 10% CO2/N2was allowed to flow into the system for 90 minutes to saturate the adsorbent phase. To determine ODHE properties, the additively manufactured structures were exposed to 40 mL/min of Ar and heated at 10° C./min to 750° C. for 1 hour. Next, the environment of the additively manufactured structures was cooled to 600° C. and 25 mL/min of 10% CO2/Ar was allowed to flow into the system for 1 h. Then, the system was heated at 10° C./min to the desired reaction temperature 700° C. while maintaining a flow of CO2/Ar. Upon reaching the desired temperature, the flow of CO2was terminated and 25 mL/min of 7% C2H6/Ar was delivered into the reactor. The concentration profiles of the species were collected with an MKS Cirrus II Mass Spectrometer throughout the entirety of the experiment, and the CO2adsorption capacities of the different samples were assessed with thermogravimetric analysis (TGA) on a Q500 thermogravimetric gas analyzer (TGA).

FIG.17and Table 16 show reactive properties of the additively manufactured structures. Specifically,FIG.16is a bar graph indicating the CO2adsorption capacities of the additively manufactured structures. Table 15 includes the CO2adsorbed, CO2conversion, C2H6conversion, the C2H4selectivity, and the C2H4yield.

TABLE 16CO2CO2C2H6C2H4C2H4adsorbedConversionConversionSelectivityYieldSample(mmol/g)(%)(%)(%)(%)CaO—1.327.134.379.827.4ZSM-5CaO—V/1.365.236.598.035.8ZSM-5CaO—Ni/1.066.028.996.828.0ZSM-5CaO—Ti/1.129.733.997.533.1ZSM-5CaO—Ga/3.311.233.791.330.7ZSM-5

The additively manufactured structures provided high conversion rates and high selectivity for the tested reactionary processes.

The systems and methods described herein may be used to form structures for any reactionary processes and not just those described herein. For example, the additively-manufactured structures may be used for photocatalytic absorbents in borosilicate glass and metal organic frameworks (MOF) composites, photocatalytic absorbents in borosilicate and zeolite composite systems, simultaneous adsorption and catalytic conversion of carbon dioxide on zeolite structures, for Zeolite/metal oxide systems, and for enhanced methane storage capacity for copper MOF and graphene oxide composites.

When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.