PHOTOCATALYTIC REACTORS AND RELATED METHODS

Abstract

Some of the present reactors and systems include a reactor body having a substantially-planar bottom and one or more sidewalls extending from the bottom to define a recess, the reactor body defining inlet(s) and outlet(s) for liquid and gas, and a lid configured to be coupled to the reactor body to cover the recess such that the interface between the reactor body and the lid is substantially sealed, where at least one of the reactor body and the lid is configured to transmit incident ultraviolet light into the recess, and where the reactor body is configured to receive a photocatalyst in the recess such that at least a portion of liquid delivered to the recess through the liquid inlet(s) can react with the photocatalyst in the presence of the ultraviolet light to generate gas. Some reactors and systems include liquid and gas circulation systems having pumps and conduits.

Claims

1. A photocatalytic reactor, comprising: a reactor body comprising a substantially-planar bottom and one or more sidewalls extending from the bottom to define a recess, the reactor body defining: at least one liquid inlet, at least one liquid outlet, at least one gas inlet that is distinct from the at least one liquid inlet, and at least one gas outlet that is distinct from the at least one liquid outlet, wherein each of the inlets and outlets of the reactor body are in fluid communication with the recess; and a lid configured to be coupled to the reactor body to cover the recess such that the interface between the reactor body and the lid is substantially sealed; wherein at least one of the reactor body and the lid is configured to transmit incident ultraviolet light into the recess; and wherein the reactor body is configured to receive a photocatalyst in the recess such that at least a portion of liquid delivered to the recess through the at least one liquid inlet can react with the photocatalyst in the presence of the ultraviolet light to generate gas.

2. The reactor of claim 1, wherein the recess of the reactor body has a maximum height and a maximum transverse dimension that is greater than the maximum height.

3. The reactor of claim 2, wherein the maximum transverse dimension is at least 5 times greater than the maximum height.

4. The reactor of claim 1, wherein the recess is configured such that the liquid is in direct contact with the photocatalyst when the liquid reacts with the photocatalyst in the presence of the ultraviolet light to generate gas.

5. The reactor of claim 1, comprising an aerogel layer disposed on an interior surface of at least one of the lid and the reactor body, wherein the aerogel layer comprises a photocatalyst.

6. A photocatalytic reactor system, comprising: a reactor of claim 1; a liquid delivery system comprising a pump, a first conduit configured to be coupled to an outlet of the pump and the at least one liquid inlet of the reactor body, and a second conduit configured to be coupled to an inlet of the pump and the at least one liquid outlet of the reactor body; and a gas circulation system comprising a pump, a first conduit configured to be coupled to an outlet of the pump and the at least one gas inlet of the reactor body, and a second conduit configured to be coupled to an inlet of the pump and the at least one gas outlet of the reactor body, wherein at least one of the reactor body and the lid is configured to transmit incident ultraviolet light into the recess, and wherein the reactor body is configured to receive a photocatalyst in the recess such that reaction of at least a portion of the liquid with the photocatalyst in the presence of the ultraviolet light can generate gas.

7. The system of claim 6, wherein the gas circulation system comprises a valve coupled to at least one of the first and second conduits and configured to selectively interrupt the flow of gas through the at least one of the first and second conduits.

8. The system of claim 6, wherein the recess is configured such that the at least a portion of the liquid directly contacts the photocatalyst when the liquid reacts with the photocatalyst in the presence of the ultraviolet light to generate gas.

9. The system of claim 6, wherein the liquid delivery system is configured to continuously circulate liquid through the recess via the at least one liquid inlet and the at least one liquid outlet or fill a majority of the recess with liquid.

10. The system of claim 6, wherein a photocatalyst is disposed on an interior surface of at least one of the lid and the reactor body, and wherein the photocatalyst comprises an aerogel layer, a film coating, an electroconductive material and a metal oxide, or a combination thereof.

11. (canceled)

12. The system of claim 6, wherein a liquid is disposed in the liquid delivery system and the liquid comprises a reactant and a sacrificial agent.

13. The system of claim 6, wherein the reactor is configured to be positioned at an angle relative to a surface above which the reactor is supported.

15. The system of claim 13, further comprising a stand configured to support the reactor body above a surface in at least a first position in which the reactor body is substantially level, and a second position in which the reactor body is angled relative to the surface.

14. The system of claim 6, further comprising a gasket configured to be disposed between the lid and the one or more sidewalls of the reactor body to seal the interface between the reactor body and the lid.

15. The system of claim 14, wherein at least one of the reactor body and the lid defines a groove configured to receive the gasket, and wherein at least one of the reactor body and the lid comprises one or more polymers, a transparent material, or both.

16. (canceled)

17. The system of claim 6, wherein the recess has a quadrilateral shape, a rectangular shape, or a square shape.

18. The system of claim 6, wherein liquid is disposed in the recess, and a photocatalyst is suspended in and/or on the liquid.

19. The system of claim 6, further comprising: a light source configured to deliver light to the reactor, wherein the light comprises ultraviolet light.

20. A method of producing hydrogen gas (H.sub.2) using a reactor of claim 1, comprising: delivering a liquid to the recess through the liquid inlet of the reactor body such that the liquid contacts a photocatalyst in the recess in the presence of ultraviolet light to produce gas; and removing at least a portion of the produced gas from the recess through the gas outlet of the reactor as a gas stream; wherein the lid is coupled to the reactor body such that the lid covers the recess and the interface between the reactor body and the lid is substantially sealed; and wherein at least a portion of the gas stream comprises H.sub.2.

21. The reactor of claim 1, wherein the reactor body includes a protrusion extending across the recess such that, when liquid flows through the at least one liquid inlet, the liquid passes over the protrusion before reaching the at least one liquid outlet.

22. The reactor of claim 21, wherein: the bottom of the reactor body defines a depression; and the at least one liquid outlet is defined within the depression and/or by a sidewall of the reactor body that is adjacent to the depression.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The following drawings illustrate by way of example and not limitation. For the sake of brevity and clarity, every feature of a given structure is not always labeled in every figure in which that structure appears. Identical reference numbers do not necessarily indicate an identical structure. Rather, the same reference number may be used to indicate a similar feature or a feature with similar functionality, as may non-identical reference numbers. The figures are drawn to scale (unless otherwise noted), meaning the sizes of the depicted elements are accurate relative to each other for at least the embodiment depicted in the figures.

[0032] FIG. 1A is a perspective view of one embodiment of the present reactors.

[0033] FIG. 1B-1C are top and perspective views, respectively, of the reactor of FIG. 1A.

[0034] FIG. 1D is a perspective view of the reactor of FIG. 1A, showing a removable lid.

[0035] FIG. 2A and 2B are perspective and cutaway perspective views, respectively, of the reactor of FIG. 1A showing an adjustable stand.

[0036] FIG. 3A is a perspective view of one embodiment of the present systems.

[0037] FIG. 3B is a top view of the system of FIG. 3A.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0038] Photocatalytic reactors can be suitable for a variety of purposes (e.g., with applications ranging from environmental clean up to hydrogen production) [7-14].

[0039] The photo-assisted dissociation (e.g., splitting) of water into hydrogen and oxygen can be achieved with external bias and without the need for such an external bias. Currently, however, only relatively low hydrogen evolution rates have been achieved. Additionally, in systems employing wide-bandgap semiconductor photocatalysts (e.g., TiO.sub.2 and other related materials), ultraviolet light (e.g., with an energy greater than 3 electron volts (eV)) may be needed to excite photocatalytic reactions, and this need may pose issues for practical applications. Attempts to improve the photocatalytic reaction include the use of modified photocatalysts which, unlike pure TiO.sub.2, respond to visible light (e.g., sunlight), but have met with relatively limited success.

[0040] Conventional reactors can be configured for photocatalysts in a variety of configurations, such as, for example, a thin layer coated on an interior surface of the reactor, suspended particles (e.g., within and/or including a liquid, such as forming part of a slurry), aerogels (e.g., within a liquid and/or floating on a liquid interface), and/or the like. As used in this disclosure, liquid includes, but is not limited to, water, sacrificial agents, organic compounds, particulate matter, slurries, mixtures thereof, and/or the like.

[0041] Referring now to the drawings, and more particularly to FIGS. 1A-1D, shown therein and designated by the reference numeral 10 is one embodiment of the present reactors. In the embodiment shown, reactor 10 includes a reactor body 14 having a substantially-planar bottom 18 and one or more sidewalls 22 that extend from the bottom to define a recess 26.

[0042] In this embodiment, reactor body 14 defines at least one liquid inlet (e.g., opening) 30 (e.g., two (2) liquid inlets), and at least one liquid outlet (e.g., opening) 34 (e.g., one (1) liquid outlet). In the embodiment shown, liquid outlet 34 is defined within or adjacent to (e.g., by a sidewall 22 adjacent to) a depression 36 defined by bottom 18, which can encourage liquid flow through liquid outlet 34. In the depicted embodiment, liquid outlet 34 has a larger cross-sectional flow area than liquid inlets 30 (e.g., to maintain a mass flow rate of liquid through reactor 10, if desired). As shown, the liquid inlet(s) are defined on an opposite side of reactor body 14 from the liquid outlet(s) (e.g., the liquid inlet(s) are defined on an opposing sidewall 22 from the liquid outlet(s)). In this way, for example, flow of liquid through a majority of recess 26 can be facilitated.

[0043] In the embodiment shown, reactor body 14 defines at least one gas inlet (e.g., opening) 38 and at least one gas outlet (e.g., opening) 42. In this embodiment, the gas inlet(s) are defined on an opposite side of reactor body 14 from the gas outlet(s) (e.g., the gas inlet(s) are defined on an opposing sidewall 22 from the gas outlet(s)). In the embodiment shown, each of the gas and/or liquid inlet(s) and/or outlet(s) (e.g., 30, 34, 38, 42, and/or the like) are configured to be in fluid communication with recess 26.

[0044] As shown, reactor body 14 of reactor 10 includes a step or protrusion 46 that extends into recess 26. In this embodiment, step or protrusion 46 can function to agitate, mix, and/or accelerate gas and/or liquid flow into and/or through reactor 10 (e.g., by reducing the vertical cross-sectional (e.g., flow) area of a portion of recess 26, for example, near liquid inlet(s) 30 and/or gas inlet(s) 38), which can facilitate photocatalytic reactions within the reactor as described below.

[0045] In the embodiment shown, recess 26 of reactor body 14 has a maximum height 50 (e.g., excluding depression 36 and step or protrusion 46) and a maximum transverse dimension 54 that is greater than the maximum height. For example, in the depicted embodiment, maximum transverse dimension 54 is greater than any one of or between any two of 1.1, 1.2, 1.3, 1.4, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, or more times greater than (e.g., five (5) times greater than) maximum height 50. In the embodiment shown, reactor 10 has a height 58 of 15 centimeters (cm), a length 62 of 100 (cm), and a width 66 of 100 (cm). For example, in this embodiment, reactor 10 and/or recess 26 can include a square shape; however, in other embodiments, the reactors and/or recesses can include any suitable shape, such as, for example, rectangular, quadrilateral, and/or otherwise polygonal, circular, elliptical, and/or otherwise round.

[0046] In this embodiment, recess 26 is defined by body 14 such that if a photocatalyst is disposed within the recess and liquid is flowing through the reactor, at least a portion (up to and including all) of the liquid (e.g., remaining in a liquid state) is in direct contact with the photocatalyst. For example, in this embodiment, a single recess 26 extends the entire distance between sidewalls 22 (e.g., as a single chamber, in direct fluid communication with bottom 18, liquid inlet(s) 30 and outlets 34, and gas inlet(s) 38 and outlet(s) 42, and open to at least a majority of the interior surface of each sidewall 22). As described below, photocatalysts suitable for use in the present reactors can include a variety of materials and/or configurations. By way of example, region 72, which is a suitable location for a photocatalyst (e.g., or liquid) within reactor 10 and/or recess 26, extends completely across the recess and includes interior surfaces of bottom 18, sidewalls 22, reactor body 14, lens 94, and lid 74.

[0047] In the embodiment shown, reactor 10 includes a lid 74 (shown in transparent fashion in FIGS. 1C and 1D) configured to be coupled to reactor body 14 to cover recess 26 such that the interface between the reactor body and the lid is substantially sealed. For example, in this embodiment, reactor 10 includes a gasket 78 configured to be disposed between lid 74 and one or more sidewalls 22 of reactor body 14 to seal the interface between the rector body and the lid (e.g., in an air- and/or liquid-tight fashion). Gasket 78 can include any suitable material, such as, for example, rubber, silicone, cork, paper, metal, and/or the like.

[0048] In this embodiment, gasket 78 can be received within a groove 82 (e.g., having a 5 millimeter (mm) depth), defined by at least one of reactor body 14 and lid 74, and surrounding recess 26. For example, in this embodiment, body 14 includes a flange 86 coupled to sidewalls 22 opposite bottom 18, wherein groove 82 is defined. As shown, gasket 78 can be resealable (e.g., reusable) in order to facilitate introduction and/or removal of catalyst(s) into and/or out of reactor 10 and/or maintenance, modification, and/or the like of reactor 10 and/or associated components. In other embodiments, however, gasket 78 may not be resealable, and may instead be configured to be replaced each time lid 74 is removed from reactor body 14. In this embodiment, an air- and/or liquid-tight seal can be provided by compressing gasket 78 between reactor body 14 and lid 74, for example, by inserting fasteners through a plurality of holes 90 configured to couple the lid to the body.

[0049] Reactor bodies (e.g., 14) and/or lids (e.g., 74) of the present reactors can include any suitable material, such as, for example, one or more: polymers (e.g., thermoplastic polymers), acrylates, polyacrylates, polymethacrylates, polyvinyl alcohols, polyolefins, and/or the like.

[0050] In this embodiment, at least one of reactor body 14 and lid 74 is configured to transmit incident light (e.g., visible light, UV light, and/or the like) into recess 26. For example, reactor body 14 and/or lid 74 (e.g., lid 74, in this embodiment) can comprise a lens 94 (e.g., comprising a material that is translucent and/or transparent). For example, lens 94 can include any suitable material, such as, for example, silica, polymeric material, quartz, borosilicate, acrylate polymers (e.g., Pyrex), copolymers, polymethylmethacrylate (e.g., PMMA), polycarbonate, mixtures thereof, and/or the like.

[0051] As shown, in this embodiment, lens 94 can be coupled to lid 74 in a sealed fashion, for example, through a flange 106 having a groove 102 configured to receive a gasket 98, similarly as to described above for the sealed interface between lid 74 and reactor body 14 (e.g., such that lens 94 is sealed and/or secured between flange 106 of lid 74 and flange 86 of reactor body 14). However, in other embodiments, lens 94 can be nonremovably coupled to and/or unitary with lid 74. In this embodiment, lens 94 is not configured to substantially modify incoming light (e.g., is window-like), however, in other embodiments, lens 94 can be configured to focus, disperse, and/or otherwise modify incoming light (e.g., through concave or convex features, whether included in a conventional or Fresnel-type structure).

[0052] In this embodiment, reactor body 14 is configured to receive a photocatalyst in recess 26 such that at least a portion of liquid delivered to the recess through at least one liquid inlet 30 can react with the photocatalyst in the presence of the light (e.g., transmitted through lens 94) to generate gas. The present reactors can work with any suitable liquid, such as, for example, water, sacrificial agents, organic compounds, particulate matter, slurries, mixtures thereof, and/or the like.

[0053] Photocatalysts suitable for use in the present disclosure can include any suitable material, such as, for example metal oxides, electroconductive materials, and/or the like, and perhaps more importantly, can include any suitable structure. For example, photocatalysts can be configured as a thin layer (e.g., or aerogel) or film coated on an interior surface of the recess and/or reactor (e.g., via spray coating, drop casting, and/or the like, on, for example, an interior surface of bottom 18, lens 94, lid 74, and/or the like), suspended particles (e.g., within and/or comprising a liquid that can be communicated into recess 26, such as, for example, forming party of a slurry), aerogels (e.g., suspended within a liquid and/or on a liquid interface within recess 26), and/or the like. Particularly, photocatalysts comprising an aerogel may allow maximization of reactive surface area, and can have thicknesses tailored to harvest light with maximum efficiency.

[0054] As shown in FIG. 2A and 2B, reactor 10 is configured to be positioned at an angle 110 relative to a surface 114 above which the reactor is supported. For example, in this embodiment, reactor 10 includes a stand 118 (e.g., tri-pod) configured to support reactor body 14 above surface 114 in any of at least a first position in which the reactor body is substantially level (e.g., as shown) and a second position in which the reactor body is angled relative to the surface (e.g., at an angle 110, which is greater than any one of or between any two of 1, 2, 3, 4, 5, 7.5, 10, 12.5, 15, 20, 25 degrees or larger). For example, in this embodiment, stand 118 includes a plurality of legs 122 each slidably coupled to reactor body 14 (e.g., via a support frame 126 to which reactor body 14 may be secured or otherwise supported, as shown).

[0055] In the embodiment shown, stand 118 includes a plurality of handles 130, each configured to releasably secure a portion of reactor body 14 relative to a leg 122. For example, one or more handles 130 can be actuated to allow reactor body 14 (and/or support frame 126) to slide relative to one or more legs 122 to place reactor 10 in a desired orientation (e.g., an angle 110 relative to surface 114). In this embodiment, one or more handles 130 can be actuated to releasably secure the reactor in the desired orientation. In this way, the orientation of the reactor relative to the surface can be adjusted, for example, to maximize and/or otherwise adjust the amount of light incident on recess 26 (e.g., to maximize and/or otherwise adjust photocatalytic reactions within reactor 10). Such orientation adjustments can be facilitated by the provision of a plurality of wheels 134, each coupled to a leg 122 at an end that is adjacent to surface 114.

[0056] As shown in FIGS. 3A and 3B, reactor 10 can form part of a system 138. In this embodiment, system 138 includes a liquid delivery system 142 and a gas circulation system 146 (described below). Liquid delivery system 142 includes a liquid pump 150. Pumps of the present systems can include any suitable pumps, such as, for example, positive displacement pumps (e.g., diaphragm pumps, peristaltic pumps, screw pumps, and/or the like), centrifugal pumps, and/or the like. In this embodiment, liquid delivery system 142 includes a first liquid conduit 154 (e.g., tubing, piping, and/or the like) configured to be coupled to an outlet 158 of the liquid pump and at least one liquid inlet 30 of reactor body 14 (e.g., two liquid inlets 30, as shown). In this embodiment, at least a portion of the liquid delivery system forms a closed loop system. For example, as shown, liquid delivery system 142 includes a second liquid conduit 162 configured to be coupled to an inlet 166 of liquid pump and at least one liquid outlet 34 of the reactor body. In the embodiment shown, liquid delivery system 142 includes a liquid reservoir 174, which can be configured to store liquid. In this embodiment, one or more liquid valve(s) 170 can be configured to selectively activate or deactivate liquid flow into, out of, and/or through reactor 14 (e.g., via valve 170a), liquid reservoir 174 (e.g., via valve 170b), and/or the like, as well as function as a pressure relief valve (e.g., to assure safe operation of system 138).

[0057] Liquid delivery systems of the present reactors and/or systems can be configured to work in batch (e.g., a certain volume of liquid communicated into reactor 10 and/or recess 26) and/or continuous mode (e.g., continuous communication of liquid through reactor 10 and/or recess 26, for example, via continuous operation of liquid pump 150). To illustrate, in batch mode, liquid delivery system 142 can configured to fill a majority of (up to and including all of) recess 26 with liquid. For example, valve 170a can be closed to prevent liquid from leaving recess 26 through liquid outlet(s) 34, and liquid pump 150 can be operated to pump liquid into recess 26 through liquid inlet(s) 30 (e.g., and can communicate liquid to and/or from liquid reservoir 174, if desired, depending on position of valve 170b) thus filling recess 26 with liquid. Once a desired volume of liquid is within (e.g., or the liquid has reached a desired depth within) recess 26, liquid pump 150 can be deactivated. In continuous mode, liquid delivery system 142 can be configured to continuously circulate liquid through recess 26. For example, valve 170a can be opened and liquid pump 150 can be actuated to communicate liquid into recess 26 through liquid inlet(s) 30, wherein the liquid may flow out of recess 26 through liquid outlet(s) 34 and can return to the pump (e.g., through second liquid conduit 162).

[0058] In the embodiment shown, gas circulation system 146 of system 138 includes a gas pump 176, a first gas conduit 178 configured to be coupled to an outlet 182 of the pump and at least one gas inlet 38 of reactor body 14. In this embodiment, gas circulation system 146 includes a second gas conduit 186 configured to be coupled to an inlet 190 of gas pump 176 and at least one gas outlet 42 of reactor body 14. In the embodiment shown, gas circulation system 146 includes one or more gas valves 194, which can be configured to selectively activate or deactivate gas flow into, out of, and/or through reactor 14, and/or the like, as well as function as a pressure relief valve (e.g., to assure safe operation of system 138).

[0059] For example, a gas valve 194 can be configured to selectively direct gas to a gas chromatograph 198. To illustrate, when valve 194 is in a first (e.g., opened) position, a gas stream can be continuously recirculated by gas pump 176 (e.g., through recess 26), and when valve 194 is in a second (e.g., closed) position, a volume of gas can be sent to gas chromatograph 198 (e.g., for analysis). Gas chromatograph 198 can be configured to determine an amount of gas (e.g., H.sub.2) generated (e.g., whether the amount has reached a desired threshold).

[0060] In the embodiment shown, system 10 includes a light source 202 configured to deliver light (e.g., 206) (e.g., visible light, UV light, and/or the like). Light source 202 can include any suitable light source, such as, for example, the sun, a lamp, a radiation source, and/or the like.

[0061] Some embodiments of the present methods for producing hydrogen gas (H.sub.2) using a reactor of the present disclosure (e.g., 10) include delivering a liquid to the recess (e.g., 26) through the liquid inlet (e.g., 30) of the reactor body (e.g., 14) such that the liquid contacts a photocatalyst in the recess in the presence of ultraviolet light to produce gas, and removing at least a portion of the produced gas from the recess through the gas outlet (e.g., 42) of the reactor as a gas stream, where the lid (e.g., 74) is coupled to the reactor body such that the lid covers the recess and the interface between the reactor body and the lid is substantially sealed, where at least a portion of the gas stream includes H.sub.2.

[0062] In some embodiments, the photocatalyst is disposed on an interior surface of at least one lid (e.g., 74) and the reactor body (e.g., 14). In some embodiments, the photocatalyst includes an aerogel layer. In some embodiments, the photocatalyst includes a film coating. In some embodiments the photocatalyst is suspended in and/or on the liquid.

[0063] In some embodiments the liquid includes water and a sacrificial agent. In some embodiments the contacting includes continuously circulating the liquid through the reactor. Some embodiments include delivering the liquid to the recess (e.g., 26) such that the liquid reaches a desired depth in the recess.

[0064] Some embodiments include analyzing a portion of the gas stream (e.g., with gas chromatograph 198) to determine the amount of H.sub.2. Some embodiments include circulating the gas stream through the at least one gas inlet (e.g., 38) and the at least one gas outlet (e.g., 42) until an amount of H.sub.2 reaches a predetermined threshold.

[0065] The above specification and examples provide a complete description of the structure and use of illustrative embodiments. Although certain embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. As such, the various illustrative embodiments of the methods and systems are not intended to be limited to the particular forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and embodiments other than the one shown may include some or all of the features of the depicted embodiment. For example, elements may be omitted or combined as a unitary structure, and/or connections may be substituted. Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples having comparable or different properties and/or functions, and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments.

[0066] The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.