Derivative carbon porous material, preparation method and application thereof, and atmospheric water collection device and method

Abstract

The present invention relates to the technical field of photothermal atmospheric water collection, and discloses a derived carbon porous material, a preparation method and application thereof, and an atmospheric water collection device and method. The derived carbon porous material comprises carbon, oxygen, hydrogen, and nitrogen. Based on the total amount of the derived carbon porous material, the nitrogen content is 12-20 wt %, based on the total molar amount of the nitrogen element, the molar content of pyrrolic nitrogen and / or pyridinic nitrogen is above 50%, and the micropore volume of the derived carbon porous material is 0.2-0.7 cm 3 The derived carbon porous material provided by the present invention has a good adsorption capacity for water vapor and has an excellent thermal conversion capacity under certain light conditions, thereby achieving rapid water desorption.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermal atmospheric water collection, and in particular to a derivative carbon porous material, a preparation method and application thereof, and an atmospheric water collection device and method. Background Art

[0002] "Water is the driving force of nature." With global warming, population growth, and water pollution, the demand for freshwater resources is surging. A United Nations report predicts that by 2050, due to surface water pollution and the depletion of groundwater reservoirs, more than half of the world's population will face life-threatening freshwater shortages. To address this, water desalination technologies such as flash evaporation and distillation have been proposed. However, these technologies require complex infrastructure and high energy consumption, hindering their widespread adoption. The atmosphere is rich in water resources, existing in the form of vapor and water droplets. According to statistics, the total amount of water in the atmosphere is 129 trillion liters, six times the total volume of water in the world's rivers. This vast natural reservoir, atmospheric water harvesting, is an effective strategy to alleviate water shortages and has attracted widespread attention from scholars both domestically and internationally. To address this global water shortage, researchers have developed a range of atmospheric freshwater production technologies, with fog collection, dewpoint harvesting, and adsorption-based atmospheric water harvesting being the three main atmospheric water harvesting (AWH) technologies. Fog harvesting technology uses biomimetic principles to collect fog using various mesh structures and condense it into liquid water. However, this technology only works in high-altitude, foggy, and windy environments, severely limiting its universal applicability. Dew-point water harvesting is a passive cooling method that requires no external energy input. However, it is highly dependent on environmental factors such as ambient temperature, relative humidity, and wind speed, and the condenser requires high process technology, making it unsuitable for large-scale application. Adsorption-based water harvesting technology has developed rapidly in recent years. This technology can be applied to atmospheric water harvesting in environments with varying temperatures and humidities, depending on the properties of the adsorbent, and can operate under extremely low relative humidity conditions. Water vapor in the atmosphere is adsorbed by the adsorbent, gradually reaching saturation. The water vapor attached to the adsorbent's surface and pores is then released into the environment through heating treatment such as light exposure. The released water vapor then condenses into water under the influence of the temperature difference, achieving the goal of water production.

[0003] Research trends in atmospheric water harvesting technology are primarily focused on the development of novel adsorbents that can effectively adsorb water vapor even at very low relative humidity and rapidly release it under low heat or light intensity. Commonly used water adsorbent materials include hygroscopic salts, zeolites, porous silicon-based materials, metal-organic frameworks, and carbon-based compounds. Hygroscopic salts can absorb over 95% of their mass in water. However, inorganic metal salts face the problem of particle agglomeration during hydration and are prone to forming a passivation layer on the surface of the salt particles, further reducing their water absorption capacity. Zeolites, as cage-like structures, can adsorb a large number of molecules, but they suffer from high regeneration temperatures, low adsorption capacity, and low thermal conductivity. Porous silicon-based materials offer advantages such as low cost, high specific surface area, rapid adsorption-desorption kinetics, and environmental friendliness. However, they suffer from high overall desorption energy consumption. Metal-organic frameworks (MOFs) are a new type of porous material with a framework structure self-assembled by inorganic metal ions and organic ligands through coordination bonds. They have the characteristics of high porosity, large specific surface area, adjustable pore size and diverse topological structures. Therefore, they have great potential in the field of atmospheric water harvesting. However, the proportion of MOF's nitrogen and oxygen functional groups, which are highly water-absorbing active sites, is generally low, which limits the water absorption capacity of MOF. In addition, because MOFs themselves have extremely low photothermal conversion capabilities, they usually need to be mixed with solar absorbers such as carbon black and graphite powder to achieve solar thermal desorption function. Due to the extremely low thermal conductivity between MOFs and solar absorbers, the overall energy utilization rate of MOFs adsorbents is low, which greatly limits the development of MOFs adsorption in the field of atmospheric water harvesting.

[0004] Currently, an effective strategy to overcome the inherently weak water absorption and lack of light absorption properties of MOFs is to carbonize them through pyrolysis to form derived carbons. This thermal conversion process allows some of the MOF's metal clusters to be easily separated from the framework, allowing nitrogen heterocyclic functional groups to be distributed around the remaining metal clusters, thereby enhancing the MOF's water absorption properties. The zeolitic imidazole framework, a flagship member of the MOF family, boasts high nitrogen content, simple synthesis, and structural stability. After carbonization and pyrolysis, it retains its original porous crystalline structure and contains a significantly higher nitrogen percentage than other MOF-derived carbons, significantly boosting the adsorption and desorption kinetics of the derived carbons. Importantly, the black color of the derived carbons eliminates the need for physical mixing with light absorbers such as carbon black, allowing for photothermal conversion and increasing the material's heat transfer efficiency. Therefore, MOF-derived carbons only need to operate in conjunction with a condenser during dehydration to achieve efficient water production. However, most current MOF-derived carbons struggle to combine a high surface area with numerous active sites for heteroatom water adsorption. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and provide a derivative carbon porous material, a preparation method and application thereof, and an atmospheric water collection device and method. The preparation method of the derivative carbon porous material is simple, and it has a good adsorption capacity for water vapor, and has excellent thermal conversion capacity under certain lighting conditions, thereby achieving rapid water desorption.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a derived carbon porous material, wherein the derived carbon porous material comprises carbon, oxygen, hydrogen and nitrogen. The content of nitrogen is 12-20 wt % based on the total amount of the derived carbon porous material, and the molar content of pyrrolic nitrogen and / or pyridinic nitrogen is above 50% based on the total molar amount of nitrogen. The micropore volume of the derived carbon porous material is 0.2-0.7 cm 3 / g.

[0007] A second aspect of the present invention provides a method for preparing a derived carbon porous material, the method comprising the following steps:

[0008] (1) subjecting a zeolite imidazole framework precursor to high-temperature pyrolysis to obtain a carbonized precursor;

[0009] (2) treating the carbonized precursor with an acid solution;

[0010] The conditions of the high-temperature pyrolysis treatment include: in an inert atmosphere, a heating rate of 2-7°C / min, and a temperature of 700-850°C;

[0011] The conditions for the acid treatment include: the acid is an inorganic acid, and the concentration of the acid solution is 1-5 mol / L.

[0012] The third aspect of the present invention provides an application of the derived carbon porous material described in the first aspect or the derived carbon porous material prepared by the method described in the second aspect in atmospheric water collection.

[0013] A fourth aspect of the present invention provides an atmospheric water collection device, comprising:

[0014] an absorption / desorption unit, at least a portion of the absorption / desorption unit supporting at least one adsorbent; wherein the at least one adsorbent absorbs water from ambient air when the absorption / desorption unit is in an absorption mode and desorbs the water as water vapor when the absorption / desorption unit is in a desorption mode;

[0015] at least one condensing unit configured to condense water vapor into liquid water;

[0016] The adsorbent is selected from the derivative carbon porous material described in the first aspect or the derivative carbon porous material prepared by the method described in the second aspect.

[0017] A fifth aspect of the present invention provides a method for collecting atmospheric water, the method comprising:

[0018] a) Using adsorbents to absorb water from the surrounding air;

[0019] b) desorbing at least a portion of the water absorbed by the adsorbent in the form of water vapor;

[0020] c) condensing the water vapor to produce liquid water;

[0021] The adsorbent is selected from the derivative carbon porous material described in the first aspect or the derivative carbon porous material prepared by the method described in the second aspect.

[0022] The derivative carbon porous material of the present invention adopts a zeolite imidazole framework with high porosity, numerous active adsorption sites and a certain hydrolytic stability as a precursor, and forms a porous derivative carbon with a high nitrogen doping amount through thermal conversion and acid treatment to achieve excellent atmospheric water collection function. In the process of thermally converting MOFs into derivative porous carbon, metal ions can be easily separated from the ligands, leaving nitrogen-rich active sites around the metal clusters, thereby improving the water adsorption capacity. On the other hand, the microporous properties of the material will be further increased by acidifying the derivative carbon. More importantly, the black color of the derivative carbon itself can give the material its own photothermal conversion ability. Therefore, the MOFs derivative carbon only needs to work in conjunction with the condenser during the dehydration process to achieve efficient atmospheric water production performance.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention starts from the design level of active adsorption molecules. It first uses a room temperature solvent method to synthesize a zeolite imidazole skeleton precursor with a regular pore structure, then obtains a carbonized product by a high-temperature pyrolysis method, and then removes free metal clusters through acidification treatment to obtain a derivative carbon with a high nitrogen doping amount and a high specific surface area. The synthesized derivative carbon porous material can quickly capture water molecules in the atmosphere through the synergistic effect of highly active adsorption sites such as pyrrole nitrogen and pyridinic nitrogen and irregular pores, and the derivative carbon material has excellent water adsorption performance. The present invention is simple to synthesize and has a high yield, and the resulting derivative carbon porous material has the characteristics of high water absorption, fast adsorption and desorption rate, and strong recyclability. Specifically, the present invention has the following advantages:

[0025] (1) The nitrogen content of the derived carbon porous material prepared by the present invention is as high as 12% or more (preferably 14% or more), of which strong water-absorbing groups such as pyridinic nitrogen and pyrrolic nitrogen account for more than 50% of the total nitrogen, providing a large number of adsorption sites for the attachment of water molecules, ensuring the rapid adsorption and enrichment of water vapor.

[0026] (2) The derived carbon porous material prepared by the present invention has a light absorption rate of more than 95%, and thanks to its outstanding photothermal conversion ability, it can reach a surface temperature of 80°C within 10 minutes, providing sufficient power for the rapid desorption of the adsorbent.

[0027] (3) The derived carbon porous material of the present invention is simple to synthesize and has a high yield. It can be combined with hydrogels, sponges, etc. to prepare adsorption blocks, thereby increasing the practical applicability and durability of the adsorbent.

[0028] (4) The atmospheric water collection device of the present invention is simple, convenient, and easy to carry. The device can be assembled from lightweight acrylic materials, with low raw material and process costs. The device is easy to operate, the adsorbent can be replaced at any time, and it is highly compatible with various adsorbents. After optimizing the thermodynamic and kinetic parameters of the device, a water production efficiency of up to 80% was achieved.

[0029] (5) The application of the derived carbon porous material and atmospheric water collection device of the present invention in atmospheric water collection is highly universal. The derived carbon porous material of the present invention can be applied to various climate environments. Due to the strong hydrolytic stability and stable chemical properties of the derived carbon, temperature, humidity and other conditions have little effect on the working efficiency of the adsorbent. This material is widely applicable to water production in various environments, solving the problem of water shortage in various regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of a condensation wall and a light-transmitting cover in an atmospheric water collection device according to a specific embodiment of the present invention;

[0031] Figure 2 Schematic diagram of the water production process of the atmospheric water collection device using derived carbon porous materials as adsorbents. DETAILED DESCRIPTION

[0032] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0033] The first aspect of the present invention provides a derived carbon porous material, wherein the derived carbon porous material comprises carbon, oxygen, hydrogen and nitrogen. The content of nitrogen is 12-20 wt % based on the total amount of the derived carbon porous material, and the molar content of pyrrolic nitrogen and / or pyridinic nitrogen is greater than 50% based on the total molar amount of nitrogen. The micropore volume of the derived carbon porous material is 0.2-0.7 cm 3 / g.

[0034] According to a preferred embodiment of the present invention, based on the total amount of the derived carbon porous material, the content of nitrogen is 14-20 wt %.

[0035] According to a preferred embodiment of the present invention, based on the total molar amount of nitrogen element, the molar content of pyrrolic nitrogen is 14-16%, preferably 15-16%, and the molar content of pyridinic nitrogen is 36-43%, preferably 41-43%.

[0036] The derived carbon porous material provided by the present invention has a high nitrogen content and a high pyrrolic nitrogen and pyridinic nitrogen content, which is conducive to rapid water vapor capture in low humidity areas.

[0037] In the present invention, unless otherwise specified, the contents of carbon, oxygen, hydrogen and nitrogen are measured by using an elemental analyzer through an adsorption-desorption column to separate different elements.

[0038] In the present invention, unless otherwise specified, the contents of pyrrolic nitrogen and pyridinic nitrogen are obtained by analyzing the photoelectrons excited by the sample using an energy analyzer using X-ray photoelectron spectroscopy.

[0039] According to a preferred embodiment of the present invention, the micropore volume of the derived carbon porous material is 0.3-0.5 cm 3 / g.

[0040] According to a preferred embodiment of the present invention, the specific surface area of the derived carbon porous material is 900-2000m 2 / g, more preferably 1500-2000m 2 / g.

[0041] The derived carbon porous material provided by the present invention has increased microporous properties and a high specific surface area, which is more conducive to quickly capturing water molecules in the atmosphere.

[0042] In the present invention, unless otherwise specified, the specific surface area and micropore volume of the derived carbon porous material are calculated by using a specific surface area and porosity analyzer and density functional theory.

[0043] The present invention has a wide range of selection for the content of other elements in the derived carbon porous material. Preferably, based on the total amount of the derived carbon porous material, the content of nitrogen is 14-20wt% (for example, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, or any range composed of any two), and the content of carbon is 35-70wt% (for example, 35wt%, 40%, 45wt%, 50wt%, 55wt%, 60wt%). , 65wt%, 70wt%, or any range consisting of any two), the content of oxygen element is 15-45wt% (for example, it can be 15wt%, 20wt%, 25wt%, 30%, 35wt%, 40wt%, 45wt%, or any range consisting of any two), and the content of hydrogen element is 0.5-7wt% (for example, it can be 0.5wt%, 1wt%, 2wt%, 3%, 4wt%, 5wt%, 6wt%, 7wt%, or any range consisting of any two).

[0044] According to the present invention, preferably, the derived carbon porous material is obtained by subjecting a zeolite imidazole framework precursor to high-temperature pyrolysis and acidification treatment; the conditions of the high-temperature pyrolysis treatment include: in an inert atmosphere, a heating rate of 2-7°C / min, and a temperature of 700-850°C;

[0045] The conditions for the acid treatment include: using an acid solution for the acid treatment, the acid is an inorganic acid, and the concentration of the acid solution is 1-5 mol / L.

[0046] In this preferred embodiment, a zeolitic imidazole framework precursor with a regular pore structure is first used to obtain a carbonized product through high-temperature pyrolysis. This product is then subjected to an acidification treatment to remove free metal clusters, resulting in a derived carbon with a high nitrogen doping content and a high specific surface area. This further improves the water absorption capacity, adsorption / desorption rate, and recyclability of the resulting derived carbon porous material.

[0047] In the present invention, there is no particular limitation on the specific selection of the zeolitic imidazole framework precursor. Various zeolitic imidazole framework precursors conventionally used in the art can be used in the present invention, such as ZIF-67, ZIF-7, ZIF-69, etc. Preferably, the chemical formula of the zeolitic imidazole framework precursor is Zn(MeIM)2. MeIM represents 2-methylimidazole. This preferred embodiment is more conducive to improving the water absorption capacity, adsorption and desorption rate, and recycling performance of the resulting derived carbon porous material.

[0048] It should be noted that the derived carbon porous material provided by the present invention may also contain residual metals (such as Zn), and its content is not particularly limited. It is understood that the sum of the contents of each element present in the derived carbon porous material is 100%.

[0049] The specific preparation method, high-temperature pyrolysis treatment and acid treatment conditions of the zeolite imidazole framework precursor can be as described in the second aspect below, and will not be repeated here.

[0050] A second aspect of the present invention provides a method for preparing a derived carbon porous material, the method comprising the following steps:

[0051] (1) subjecting a zeolite imidazole framework precursor to high-temperature pyrolysis to obtain a carbonized precursor;

[0052] (2) treating the carbonized precursor with an acid solution;

[0053] The conditions of the high-temperature pyrolysis treatment include: in an inert atmosphere, a heating rate of 2-7°C / min, and a temperature of 700-850°C;

[0054] The conditions for the acid treatment include: the acid is an inorganic acid, and the concentration of the acid solution is 1-5 mol / L.

[0055] According to a preferred embodiment of the present invention, the conditions for the high-temperature pyrolysis treatment include: being carried out in an inert atmosphere, a heating rate of 3-6°C / min, and a temperature of 700-850°C, more preferably 700-800°C. Adopting this preferred embodiment is more conducive to the synergistic increase in the specific surface area and water adsorption sites of the MOF-derived carbon. If the temperature of the high-temperature pyrolysis treatment is too low, it is not conducive to improving the specific surface area and porosity of the MOF-derived carbon. If the temperature of the high-temperature pyrolysis treatment is too high, it may cause the number of water adsorption sites for heteroatoms such as nitrogen and oxygen to decrease.

[0056] Preferably, the temperature of the high-temperature pyrolysis treatment is 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, or any range therebetween.

[0057] Preferably, the high-temperature pyrolysis treatment time is 1-5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or any range therebetween, preferably 1-3 hours.

[0058] Preferably, the inert atmosphere includes at least one of nitrogen, helium, argon and neon. The embodiments of the present invention are described using nitrogen as an example, but the present invention is not limited thereto.

[0059] According to a preferred embodiment of the present invention, the high-temperature pyrolysis treatment is carried out in a flowing inert gas atmosphere. The present invention has no particular limitation on the rate of the flowing inert gas.

[0060] According to a preferred embodiment of the present invention, the inorganic acid is selected from at least one of hydrochloric acid, nitric acid, and hydrofluoric acid, more preferably hydrochloric acid. This preferred embodiment is more conducive to removing metal oxides and improving porosity in MOF-derived carbon.

[0061] The present invention has a wide range of acid solution concentrations. Preferably, the acid solution concentration is 1-3 mol / L, more preferably 2-3 mol / L. This preferred embodiment is more conducive to ensuring the yield of synthesized MOF-derived carbon and improving acid washing efficiency.

[0062] Specifically, analytically pure hydrochloric acid solution can be added to deionized water for dilution to obtain a hydrochloric acid aqueous solution with a concentration of 2-3 mol / L.

[0063] The present invention has a wide range of time for the acid treatment, based on the purpose of achieving complete removal of metal oxides in the derived carbon. Preferably, the acid treatment time is 20-30 hours, preferably 22-26 hours.

[0064] The present invention has a wide range of selections for the specific method of the acid treatment. Preferably, the carbonized precursor is added to the acid solution, immersed and stirred, and then centrifuged.

[0065] Preferably, the method further comprises washing the precipitate obtained by centrifugation after the acid treatment. The conditions for the water washing are not particularly limited. For example, the precipitate can be added to deionized water, stirred, and then centrifuged to obtain the final product. The number of water washings is not particularly limited, and for example, can be 2-6 times.

[0066] The selection range of the type of the zeolite imidazole framework precursor can be the same as that of the first aspect above, and will not be repeated here.

[0067] The present invention has no particular limitation on the preparation method of the zeolite imidazole framework precursor, as long as the zeolite imidazole framework precursor can be prepared, for example, a solvent method can be used.

[0068] Preferably, the preparation method of the zeolite imidazole framework precursor comprises: contacting a compound containing an M element with an imidazole ligand in the presence of an organic solvent, and performing solid-liquid separation on the product after the contact reaction, wherein the M is selected from at least one of Zn, Co, Zr and Cr.

[0069] Preferably, the compound containing element M can be selected from at least one of the carboxylates, carbonates, sulfates and nitrates of element M.

[0070] According to a preferred embodiment of the present invention, M is Zn. The compound containing the element M is preferably zinc nitrate. The compound containing the element M may optionally contain water of crystallization, which is not particularly limited in the present invention.

[0071] Preferably, the imidazole ligand is at least one selected from 2-methylimidazole, 1-methylimidazole, benzimidazole and tris(4-(1-imidazole)phenyl)amine, more preferably 2-methylimidazole.

[0072] Preferably, the molar ratio of the compound containing the M element to the imidazole ligand is 0.1-0.3:1.

[0073] The present invention has a wide range of selections for the type of the organic solvent, for example, it can be at least one of alcohols, amides and aromatic hydrocarbons, preferably at least one of methanol, N,N-dimethylformamide and toluene, more preferably methanol.

[0074] According to the method provided by the present invention, preferably, the preparation method of the zeolite imidazole framework precursor comprises:

[0075] (1-1) providing a solution A comprising an organic solvent and a compound containing an M element, and providing a solution B comprising an organic solvent and an imidazole ligand;

[0076] (1-2) Dropping solution B into solution A to carry out the contact reaction. In the prior art, direct mixing of solution B and solution A is often employed in the preparation of zeolite imidazole framework precursors. However, the present invention utilizes a method of dropping solution B into solution A to carry out the contact reaction, which is more conducive to forming a MOF-derived carbon precursor with a regular morphology and a small crystal diameter.

[0077] The types of organic solvents in solution A and solution B of the present invention may be the same or different, and are preferably the same.

[0078] The present invention has no particular limitation on the concentrations of solution A and solution B. The amount of organic solvent used is determined based on the requirement that the solvent method can proceed smoothly. Preferably, the concentrations of solution A and solution B are independently 0.05-0.09 mol / L and 0.5-0.7 mol / L.

[0079] According to the method provided by the present invention, preferably, the contact reaction is carried out under stirring conditions. The present invention has no particular limitation on the stirring rate, and those skilled in the art can carry out the reaction according to conventional technical means.

[0080] According to the method provided by the present invention, preferably, the contact reaction time is 24-36 hours.

[0081] According to the method provided by the present invention, preferably, the dripping rate of the solution B is 2-5 mL / min, preferably 3-4 mL / min. This preferred embodiment is more conducive to the full crystallization and regular morphology of MOF.

[0082] The method provided by the present invention also preferably includes separating (e.g., filtering) the product of the contact reaction to obtain a solid product. The method provided by the present invention also preferably includes washing the solid product. The present invention does not particularly limit the specific washing method or the type of washing agent. For example, methanol is used for washing. The number of washing times is also not particularly limited. Preferably, the solid product is washed with methanol 2-6 times.

[0083] The method provided herein also preferably involves drying the washed product. The drying step is not particularly limited and may be performed by any conventional drying method, including but not limited to oven drying and air drying. Preferably, the drying temperature is between room temperature and 80°C, and the drying time may be 2 to 48 hours.

[0084] The third aspect of the present invention provides a use of the derivative carbon porous material described in the first aspect or the derivative carbon porous material prepared by the method described in the second aspect in atmospheric water collection. The derivative carbon porous material provided by the present invention has high atmospheric water collection performance in the atmospheric water collection process.

[0085] A fourth aspect of the present invention provides an atmospheric water collection device, comprising:

[0086] an absorption / desorption unit, at least a portion of the absorption / desorption unit supporting at least one adsorbent; wherein the at least one adsorbent absorbs water from ambient air when the absorption / desorption unit is in an absorption mode and desorbs the water as water vapor when the absorption / desorption unit is in a desorption mode;

[0087] at least one condensing unit configured to condense water vapor into liquid water;

[0088] The adsorbent is selected from the derivative carbon porous material described in the first aspect or the derivative carbon porous material prepared by the method described in the second aspect.

[0089] The atmospheric water collection device provided by the present invention can achieve good light collection and efficient atmospheric water condensation, and has the characteristics of low energy consumption, high energy utilization rate and high water production rate.

[0090] The absorption / desorption unit has different working modes of absorbing water and desorbing water. The present invention has no special limitation on its specific setting method, as long as it can be ensured that when the absorption / desorption unit is in the absorption mode, the adsorbent can absorb water from the surrounding air, and when the absorption / desorption unit is in the desorption mode, it can desorb water in the form of water vapor.

[0091] The present invention does not particularly limit the location and type of the condensing unit, as long as it can condense the water vapor desorbed by the absorption / desorption unit into liquid water. The condensing unit can be a condenser. The condensing unit can be installed on the wall of the atmospheric water collection device.

[0092] According to a preferred embodiment of the present invention, the device further comprises a photothermal desorption unit, which is configured to achieve photothermal desorption of water captured by the adsorbent. This preferred embodiment achieves atmospheric water collection through sunlight irradiation.

[0093] Preferably, the curvature of the light-transmitting cover of the photothermal desorption unit is 30-60°. This preferred embodiment is more conducive to concentrating sunlight on the adsorbent surface, thereby increasing the desorption rate.

[0094] In the present invention, the curvature of the light-transmitting cover refers to the downward bending angle of the plane where the vertex of the light-transmitting cover of the photothermal desorption unit is located.

[0095] The present invention does not specifically limit the material selection for the atmospheric water collection device, but acrylic is preferred. The device is primarily assembled from lightweight acrylic, resulting in low raw material and process costs. The device is easy to operate, allows for the immediate replacement of adsorbents, and is highly compatible with various adsorbents. By optimizing the device's thermodynamic and kinetic parameters, it can achieve a water production efficiency of up to 80%.

[0096] A fifth aspect of the present invention provides a method for collecting atmospheric water, the method comprising:

[0097] a) Using adsorbents to absorb water from the surrounding air;

[0098] b) desorbing at least a portion of the water absorbed by the adsorbent in the form of water vapor;

[0099] c) condensing the water vapor to produce liquid water;

[0100] The adsorbent is selected from the derivative carbon porous material described in the first aspect or the derivative carbon porous material prepared by the method described in the second aspect.

[0101] The schematic diagram of the water production process of the atmospheric water collection device using the derived carbon porous material as an adsorbent is as follows: Figure 2 shown.

[0102] The adsorbent provided by the present invention is applicable to environments with a wide humidity range. Preferably, the humidity of the ambient air is 30-50% RH. The atmospheric water collection method provided by the present invention can be applied to various climate environments and has strong universality.

[0103] According to a preferred embodiment of the present invention, the single water absorption time of step a) is 10-30 minutes; and / or the single dehydration time of step b) is 10-30 minutes. The adsorbent in the method provided by the present invention has a fast adsorption and desorption rate.

[0104] Preferably, in step b), a photothermal desorption unit is used to desorb at least part of the water absorbed by the adsorbent in the form of water vapor, and the curvature of the light-transmitting cover of the photothermal desorption unit is 30-60°.

[0105] Due to the strong hydrolytic stability and chemical stability of the derived carbon porous material provided by the present invention, temperature, humidity, and other conditions have little effect on the adsorbent's operating efficiency. This material is widely applicable to water production in various environments, addressing water shortages in various regions.

[0106] The present invention will be described in detail below through examples.

[0107] The composition and property parameter testing methods of the derived carbon porous materials are as described above and will not be repeated here.

[0108] Unless otherwise specified, room temperature refers to 25℃±2℃.

[0109] Example 1

[0110] 1. Preparation of zeolite imidazole framework precursor:

[0111] (1) Add 1.68 g (5.6 mmol) of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) to 80 mL of methanol solvent and stir at room temperature until completely dissolved to obtain metal solution A.

[0112] (2) Weigh 4.64 g (56 mmol) of 2-methylimidazole (2-mIM) and add it to 80 mL of methanol solvent. Stir at room temperature until it is completely dissolved to obtain ligand solution B.

[0113] (3) Solution B was added to the metal solution A at a dropwise rate of 3-4 mL / min (the molar ratio of zinc source to imidazole ligand in the mixture was 0.1:1), and the mixture was rapidly stirred at 400 rpm for 24 h at room temperature.

[0114] (4) The suspension after the reaction was filtered through filter paper to obtain a white crystalline product, which was washed three times with methanol solvent and dried at room temperature for 24 hours to obtain a zeolite imidazole framework precursor with a yield of 87%. The chemical structure of the zeolite imidazole framework is Zn(MeIM)2.

[0115] 2. Preparation of MOF-derived carbon:

[0116] (1) Weigh 500 mg of the precursor obtained above and place it in a quartz boat. Then, place the quartz boat containing the sample in a tube furnace and heat it from room temperature to 800°C at a heating rate of 5°C / min in a flowing nitrogen atmosphere. Maintain it at 800°C for 2 h. After it is naturally cooled to room temperature, a derivative carbon product is obtained.

[0117] (2) The derived carbon product obtained above was added to a 2 mol / L hydrochloric acid aqueous solution and stirred for 24 hours, and then centrifuged at a rate of 12000 r / min. The powder obtained by centrifugation was then added back to deionized water and stirred for 5 hours, centrifuged again, and then re-immersed in deionized water. The above steps were repeated three times. Finally, the product was placed in an oven and dried at 70°C to obtain the final derived carbon porous material.

[0118] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0119] Comparative Example 1

[0120] The derived carbon porous material was prepared according to the method of Example 1, except that, during the preparation of the MOF-derived carbon, the high-temperature pyrolysis treatment temperature in step (1) was 900°C.

[0121] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0122] Comparative Example 2

[0123] The derived carbon porous material was prepared according to the method of Example 1, except that the preparation process of the MOF-derived carbon did not include the acid treatment process in step (2).

[0124] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0125] Example 2

[0126] The derived carbon porous material was prepared according to the method of Example 1, except that, in the preparation process of the zeolite imidazole framework precursor, the amount of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) used was 3.36 g (11.3 mmol), so that the molar ratio of the zinc source and the imidazole ligand in the mixed solution was 0.2:1; in the preparation process of the MOF-derived carbon, the high-temperature pyrolysis treatment temperature of step (1) was 700°C.

[0127] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0128] Example 3

[0129] The derived carbon porous material was prepared according to the method of Example 1, except that, in the preparation process of the zeolite imidazole framework precursor, the amount of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) used was 5.04 g (16.9 mmol), so that the molar ratio of the zinc source and the imidazole ligand in the mixed solution was 0.3:1; in the preparation process of the MOF-derived carbon, during the high-temperature pyrolysis treatment in step (1), the heating rate was 5°C / min and the temperature was 750°C.

[0130] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0131] Example 4

[0132] The derived carbon porous material was prepared according to the method of Example 1, except that during the preparation of the MOF-derived carbon, during the acid treatment in step (2), the concentration of the hydrochloric acid aqueous solution was 3 mol / L, and the treatment time was 24 h.

[0133] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0134] Example 5

[0135] The derived carbon porous material was prepared according to the method of Example 1, except that, during the preparation of the zeolite imidazole framework precursor, solution B was directly poured into the metal solution A.

[0136] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0137] Example 6

[0138] The derived carbon porous material was prepared according to the method of Example 1, except that in the preparation of the zeolite imidazole framework precursor, the amount of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) used was 6.72 g (22.59 mmol), so that the molar ratio of the zinc source and the imidazole ligand in the mixed solution was 0.4:1.

[0139] Example 7

[0140] The derived carbon porous material was prepared according to the method of Example 1, except that during the preparation of the MOF-derived carbon, the heating rate during the high-temperature pyrolysis treatment in step (1) was 10° C. / min.

[0141] Example 8

[0142] The derived carbon porous material was prepared according to the method of Example 1, except that during the acid treatment in step (2), the concentration of the hydrochloric acid aqueous solution was 4 mol / L.

[0143] Example 9

[0144] The derived carbon porous material was prepared according to the method of Example 1, except that, during the preparation of the MOF-derived carbon, the acid solution used for the acid treatment was a nitric acid aqueous solution with a concentration of 2 mol / L.

[0145] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0146] Example 10

[0147] The derived carbon porous material was prepared according to the method of Example 1, except that the zeolite imidazole framework precursor was prepared by synthesizing ZIF-67. The specific steps included:

[0148] (1) Weigh 0.25 g (0.85 mmol) of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) and dissolve it in 25 mL of methanol to obtain solution A.

[0149] (2) Weigh 0.99 g (12 mmol) of 2-methylimidazole and dissolve it in 25 mL of methanol to obtain solution B;

[0150] (3) The above solutions A and B were mixed and stirred for 30 minutes, and then the resulting mixture was transferred to a high-pressure reactor at 160°C for 24 hours;

[0151] (4) The product was centrifuged (8000 rpm, 10 min), washed with deionized water and ethanol solution, and dried to obtain a zeolite imidazole framework ZIF-67 precursor.

[0152] The composition and property parameters of the derived carbon porous materials are listed in Tables 1 and 2 below.

[0153] Table 1

[0154]

[0155]

[0156] Table 2

[0157] Pyrrolic nitrogen, mol% Pyridinic nitrogen, mol% <![CDATA[Micropore pore volume, cm 3 / g]]> <![CDATA[Specific surface area, m 2 / g]]> Example 1 15.94 42.62 0.48 1759 Comparative Example 1 9.18 5.13 0.44 2145 Comparative Example 2 13.61 37.39 0.29 1234 Example 2 15.52 42.17 0.34 1546 Example 3 15.42 41.59 0.31 1582 Example 4 15.14 41.37 0.63 1974 Example 5 14.27 38.86 0.38 1372 Example 6 14.89 36.62 0.41 2016 Example 7 14.26 36.86 0.45 1989 Example 8 15.23 36.51 0.39 2237 Example 9 14.27 40.17 0.36 1577 Example 10 13.59 39.15 0.39 1267

[0158] Test Example 1

[0159] This test example is used to test the atmospheric water absorption performance of the derived carbon porous material of Example 1.

[0160] 1. Determine the hygroscopic properties of derived carbon porous materials by simulating outdoor temperature and humidity environments

[0161] The test object is derived carbon porous material, and the sample container has a diameter of 26mm and a height of 5mm. The specifications of the designed atmospheric water collection device are as follows: Figure 1 , where Figure a is a schematic diagram of the dimensions of the condensation side wall, Figure b is a plan view of the light-transmitting cover, and Figure c is a top view of the light-transmitting cover.

[0162] The simulated temperature and humidity device is a constant temperature and humidity chamber, and deionized water is added to the chamber as the adsorbent. The hygroscopic performance test is to place the sample dish containing the derivative carbon porous material into the constant temperature and humidity chamber, where the sample stacking density will affect the water adsorption performance, the temperature conditions will affect the water adsorption amount of the sample and the water vapor diffusion rate generated by the constant temperature and humidity chamber, and the humidity conditions will affect the regeneration time. The applied variables are the sample amount of the adsorbent (100mg-300mg), temperature, humidity and adsorption time. A total of 9 condition groups are set for this test, as shown in Table 3; the average daily adsorption amount of the sample is obtained according to the above test methods, where the average daily adsorption amount is calculated based on the adsorption time of 4 hours a day. The test data are summarized in Table 4.

[0163] Table 4 shows that the derived carbon porous material exhibits good water absorption performance under different conditions of sample loading, temperature, humidity, and adsorption time. The best average daily adsorption capacity was achieved when the sample loading was 100 mg, the test temperature was 27°C, the test humidity was 40% RH, and the adsorption time was 10 minutes.

[0164] The test results of the adsorbents obtained in various embodiments and comparative examples under the conditions of test group 1 in Table 3 are shown in Table 5.

[0165] Table 3 Test conditions for each test group

[0166] Test Group Adsorbent loading amount temperature humidity Adsorption time Test Group 1 100mg 27℃ 40% RH 10min Test Group 2 200mg 27℃ 40% RH 10min Test Group 3 300mg 27℃ 40% RH 10min Test Group 4 100mg 25℃ 40% RH 10min Test Group 5 100mg 30℃ 40% RH 10min Test Group 6 100mg 27℃ 30% RH 10min Test Group 7 100mg 27℃ 50% RH 10min Test Group 8 100mg 27℃ 40% RH 20min Test Group 9 100mg 27℃ 40% RH 30min

[0167] Table 4 Moisture absorption of each test group

[0168]

[0169]

[0170] Table 5 Moisture absorption of each embodiment under optimal test conditions

[0171] Test Group Average water absorption per time Moisture absorption times Average daily water absorption Example 1 <![CDATA[358mg·g -1 ]]> 24 <![CDATA[8.59g·g -1 ·day -1 ]]> Comparative Example 1 <![CDATA[132mg·g -1 ]]> 24 <![CDATA[3.17g·g -1 ·day -1 ]]> Comparative Example 2 <![CDATA[118mg·g -1 ]]> 24 <![CDATA[2.84g·g -1 ·day -1 ]]> Example 2 <![CDATA[313mg·g -1 ]]> 24 <![CDATA[7.51g·g -1 ·day -1 ]]> Example 3 <![CDATA[289mg·g -1 ]]> 24 <![CDATA[6.93g·g -1 ·day -1 ]]> Example 4 <![CDATA[273mg·g -1 ]]> 24 <![CDATA[6.55g·g -1 ·day -1 ]]> Example 5 <![CDATA[256mg·g -1 ]]> 24 <![CDATA[6.14g·g -1 ·day -1 ]]> Example 6 <![CDATA[230mg·g -1 ]]> 24 <![CDATA[5.53g·g -1 ·day -1 ]]> Example 7 <![CDATA[220mg·g -1 ]]> 24 <![CDATA[5.28g·g -1 ·day -1 ]]> Example 8 <![CDATA[242mg·g -1 ]]> 24 <![CDATA[5.81g·g -1 ·day -1 ]]> Example 9 <![CDATA[277mg·g -1 ]]> 24 <![CDATA[6.64g·g -1 ·day -1 ]]> Example 10 <![CDATA[247mg·g -1 ]]> 24 <![CDATA[5.92g·g -1 ·day -1 ]]>

[0172] 2. Determine the water production performance of derived carbon porous materials and atmospheric water collection devices in outdoor environments

[0173] To fully demonstrate the water collection performance of the adsorbent and device, atmospheric water production was conducted on days with an average humidity range of 30-50% RH and sunshine duration exceeding 8 hours. Temperature, humidity, and sunlight intensity were recorded throughout the test using a thermohygrometer and a light intensity meter. To improve the water production efficiency of the atmospheric water collection device, a condensation element was added to the device wall to create a temperature gradient, with a condensation temperature of 1-5°C.

[0174] First, place the sample dish containing the derived carbon porous material in a light-proof environment with a certain humidity for atmospheric water absorption, and the moisture absorption time is 10-30 minutes. After the moisture absorption is completed, weigh the sample and record the weight gain of the sample. During the atmospheric dehydration stage, place the sample in the box of the atmospheric water collection device and install a light-transmitting cover. Wrap sealant around the cover to ensure the sealing of the device. The curvature of the light-transmitting cover is 30°-60°, and the size of the curvature will affect the intensity of light irradiated on the sample surface. Then place the device in sunlight and turn on the condenser assembly. At this time, liquid water begins to condense on the wall of the device, and the water production time is 10-30 minutes. After the water production is completed, take out the derived carbon porous material and weigh it. At the same time, collect the condensed liquid water and weigh it, and record the water production of the process.

[0175] This experiment set up a control group and an experimental group. The control group was an atmospheric water collection device without adding the derivative carbon porous material; the experimental group was an atmospheric water collection device with the derivative carbon porous material prepared in Example 1. The amount of derivative carbon added was 100 mg, and the bulk density of the sample in the sample dish was 131.53 mg·cm -3 .

[0176] (1) Weight gain experiment: First, the derivatized carbon was weighed using an electronic analytical balance before water adsorption. Then, the derivatized carbon sample after water adsorption was weighed after a certain moisture absorption time, and the weight gain was calculated. Three equilibrium experiments were performed for each experimental condition, and the results were averaged.

[0177] (2) Water Quality Test: During the water production process, the derived carbon placed directly below the light-transmitting cover is fully exposed to sunlight and converted into heat. The illumination time is 10-30 minutes. During this time, the water absorbed into the derived carbon porous material is evaporated. When the water vapor condenses into liquid, the liquid water is collected and the total amount of water collected is recorded using an electronic analytical balance, and the water quality is analyzed.

[0178] This test set up a total of 4 condition groups, as shown in Table 6. According to the above test methods, the average daily water production was obtained, and the test data is summarized in Table 7:

[0179] The test results in Table 7 show that the derived carbon atmospheric water collection material of the present invention has the characteristics of strong recycling and high water production rate, and has significant application value and broad market prospects.

[0180] Table 6 Test conditions for each test group

[0181] Test Group Moisture absorption time Light exposure time Average humidity Curvature of the light cover Condenser temperature Test Group 1 10min 10min 40% RH 60° 1℃ Test Group 2 20min 10min 40% RH 60° 1℃ Test Group 3 30min 10min 40% RH 60° 1℃ Test Group 4 10min 20min 40% RH 60° 1℃ Test Group 5 10min 30min 40% RH 60° 1℃ Test Group 6 10min 10min 40% RH 30° 1℃ Test Group 7 10min 10min 40% RH 45° 1℃ Test Group 8 10min 10min 40% RH 60° 3℃ Test Group 9 10min 10min 40% RH 60° 5℃

[0182] Table 7 Water production of each test group

[0183]

[0184]

[0185] In summary, the present invention is based on the highly porous structure and active adsorption site properties of the zeolite imidazole skeleton, and constructs a MOF-derived carbon photothermal hygroscopic material through pyrolysis carbonization and acid treatment strategies, and designs a novel integrated atmospheric water collection device based on the derived carbon material. The porous derived carbon material can be applied to the field of atmospheric water collection in arid areas. In the water absorption stage, the derived carbon uses its rich pore structure and nitrogen-containing active sites to absorb water vapor and lock water molecules inside its pores as a storage space. In the dehydration stage, due to its unique photothermal conversion ability, when the MOFs-derived carbon is exposed to sufficient sunlight, the sample will receive rapid heat transfer to increase its overall temperature, thereby increasing the saturated vapor pressure and driving the absorbed water to evaporate into water vapor and escape from the pore structure of the derived carbon. Finally, the free water vapor is condensed under the temperature difference provided by the condenser of the device to achieve atmospheric water production, and the metal ion content of the water collected by the device is detected by ICP inductively coupled plasma emission spectroscopy, proving that the produced water meets the drinking water standards of the World Health Organization (WHO). It can be seen that the zeolite imidazole framework-derived carbon material and the atmospheric water collection device thereof of the present invention are simple to prepare, highly recyclable, and have high water production efficiency, and have great application value and broad market prospects.

[0186] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for atmospheric water harvesting, comprising: a) Using adsorbents to absorb water from the surrounding air; b) desorbing at least a portion of the water absorbed by the adsorbent in the form of water vapor; c) condensing the water vapor to produce liquid water; The adsorbent is a derived carbon porous material, which includes carbon, oxygen, hydrogen and nitrogen. The content of nitrogen is 12-20 wt % based on the total amount of the derived carbon porous material. The micropore volume of the derived carbon porous material is 0.2-0.7 cm 3 / g; Based on the total molar amount of nitrogen element, the molar content of pyrrolic nitrogen is 15-16%, and the molar content of pyridinic nitrogen is 41-43%; The specific surface area of the derived carbon porous material is 900-2000m 2 / g; The derived carbon porous material is obtained by subjecting a zeolite imidazole framework precursor to high-temperature pyrolysis and acid treatment; The chemical structural formula of the zeolite imidazole framework precursor is Zn(MeIM)2, where MeIM represents 2-methylimidazole; In step b), a photothermal desorption unit is used to desorb at least part of the water absorbed by the adsorbent in the form of water vapor.

2. The method according to claim 1, wherein Based on the total amount of the derived carbon porous material, the content of nitrogen is 14-20 wt %.

3. The method according to claim 1, wherein The micropore volume of the derived carbon porous material is 0.3-0.5 cm 3 / g.

4. The method according to claim 1, wherein Based on the total amount of the derived carbon porous material, the content of nitrogen is 14-20 wt%, the content of carbon is 35-70 wt%, the content of oxygen is 15-45 wt%, and the content of hydrogen is 0.5-7 wt%.

5. The method according to claim 1, wherein The conditions of the high-temperature pyrolysis treatment include: being carried out in an inert atmosphere, a heating rate of 2-7°C / min, and a temperature of 700-850°C.

6. The method according to claim 1, wherein The conditions for the acid treatment include: using an acid solution for the acid treatment, the acid is an inorganic acid, and the concentration of the acid solution is 1-5 mol / L.

7. The method according to any one of claims 1 to 6, wherein: The humidity of the ambient air is 30-50% RH.

8. The method according to any one of claims 1 to 6, wherein: The single water absorption time in step a) is 10-30 minutes.

9. The method according to any one of claims 1 to 6, wherein: The single dehydration time in step b) is 10-30 minutes.

10. The method according to any one of claims 1 to 6, wherein: The curvature of the light-transmitting cover of the photothermal desorption unit is 30-60°.

11. An atmospheric water collection device, comprising: an absorption / desorption unit, at least a portion of the absorption / desorption unit supporting at least one adsorbent; wherein the at least one adsorbent absorbs water from ambient air when the absorption / desorption unit is in an absorption mode and desorbs the water as water vapor when the absorption / desorption unit is in a desorption mode; at least one condensing unit configured to condense water vapor into liquid water; The adsorbent is a derived carbon porous material, which includes carbon, oxygen, hydrogen and nitrogen. The content of nitrogen is 12-20 wt % based on the total amount of the derived carbon porous material. The micropore volume of the derived carbon porous material is 0.2-0.7 cm 3 / g; Based on the total molar amount of nitrogen, the molar content of pyrrolic nitrogen is 15-16%, and the molar content of pyridinic nitrogen is 41-43%; The specific surface area of the derived carbon porous material is 900-2000m 2 / g; The derived carbon porous material is obtained by subjecting a zeolite imidazole framework precursor to high-temperature pyrolysis and acid treatment; The chemical structural formula of the zeolite imidazole framework precursor is Zn(MeIM)2, where MeIM represents 2-methylimidazole; The device further includes a photothermal desorption unit configured to achieve photothermal desorption of moisture captured by the adsorbent.

12. The atmospheric water collection device according to claim 11, wherein: Based on the total amount of the derived carbon porous material, the content of nitrogen is 14-20 wt %.

13. The atmospheric water collection device according to claim 11, wherein: The micropore volume of the derived carbon porous material is 0.3-0.5 cm 3 / g.

14. The atmospheric water collection device according to any one of claims 11 to 13, wherein: Based on the total amount of the derived carbon porous material, the content of nitrogen is 14-20 wt%, the content of carbon is 35-70 wt%, the content of oxygen is 15-45 wt%, and the content of hydrogen is 0.5-7 wt%.

15. The atmospheric water collection device according to any one of claims 11 to 13, wherein: The conditions of the high-temperature pyrolysis treatment include: being carried out in an inert atmosphere, a heating rate of 2-7°C / min, and a temperature of 700-850°C.

16. The atmospheric water collection device according to any one of claims 11 to 13, wherein: The conditions for the acid treatment include: using an acid solution for the acid treatment, the acid is an inorganic acid, and the concentration of the acid solution is 1-5 mol / L.

17. The atmospheric water collection device according to any one of claims 11 to 13, wherein: The curvature of the light-transmitting cover of the photothermal desorption unit is 30-60°.

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