CN115975369A - Organic foam-based MOF (metal organic framework) block moisture absorbent, and thermal in-situ synthesis method and application of mixed solvent thereof - Google Patents
Organic foam-based MOF (metal organic framework) block moisture absorbent, and thermal in-situ synthesis method and application of mixed solvent thereof Download PDFInfo
- Publication number
- CN115975369A CN115975369A CN202211656651.7A CN202211656651A CN115975369A CN 115975369 A CN115975369 A CN 115975369A CN 202211656651 A CN202211656651 A CN 202211656651A CN 115975369 A CN115975369 A CN 115975369A
- Authority
- CN
- China
- Prior art keywords
- moisture absorbent
- mof
- organic
- organic foam
- mixed solvent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention discloses an organic foam-based MOF (metal organic framework) block moisture absorbent, a mixed solvent thermal in-situ synthesis method and application thereof. The method comprises the following steps: mixing DMF solution of organic dicarboxylic acid and aqueous solution of aluminum salt under stirring at room temperature to obtain uniform reaction liquid; adding the reaction liquid into a polytetrafluoroethylene lining kettle, immersing the organic foam block in the reaction liquid, sealing the reaction kettle, and reacting at the temperature of 90-130 ℃ for 10-13h; and taking out the block, washing, drying and activating to obtain the organic foam-based MOF block moisture absorbent. According to the organic foam MOF bulk moisture absorbent synthesized in situ by mixed solvent heat, MOF crystal grains are uniformly distributed and tightly combined (without powder falling) on the foam surface and in pores, and the loading rate is high (70%); has the characteristics of high water vapor adsorption capacity, low desorption temperature, good cycle stability and the like under low humidity (RH is less than or equal to 40 percent), and can be applied to an adsorption heat pump system.
Description
Technical Field
The invention belongs to the field of air conditioning dehumidification, and particularly relates to an organic foam-based MOF (metal organic framework) block moisture absorbent, a mixed solvent thermal in-situ synthesis method and application thereof.
Background
With the continuous aggravation of the energy crisis, the development of new energy and the improvement of the energy utilization rate become the key points of energy conservation and emission reduction. Among them, the adsorption heat pump technologies (AHPs) are the most widely studied for energy saving and consumption reduction. In AHPs, common adsorbates include water, methanol, ethanol, ammonia, and the like, which are widely used due to the fact that water is non-toxic and harmless, and has high evaporation enthalpy. As for the adsorbent, it is required that the adsorbent has a higher water vapor adsorption amount at a low humidity (. Ltoreq.40% RH). Therefore, the key to high adsorption heat pump technology efficiency is the adsorbent. The traditional adsorbent zeolite, silica gel and the like can not meet the application requirements. The zeolite has good adsorption performance, but the desorption temperature is high (250 ℃), and the energy consumption of the system is high; silica gel has an extremely low water absorption (0.03 g/g) at low humidity, and the like. In recent years, a novel Metal Organic Framework (MOF) adsorbent has attracted attention. The material is a porous crystal material formed by self-assembly connection of metal ions and organic ligands, has the advantages of high water vapor adsorption quantity, adjustable water vapor adsorption curve, low desorption temperature, good hydrothermal stability and the like, and has become a current research hotspot.
At present, many MOFs for AHPs have been reported, such as Al-fumarates (A520), MIL-303, MIL-160, CAU-10 of aluminum series, KMF-1, etc., which are MOFs adsorbents formed by coordination reaction of aluminum ions and different organic dicarboxylic acids (or sodium carboxylates). These adsorbents are expected to exhibit potential applications in AHP. However, these MOFs usually appear in powder form during the synthesis process, and in practical applications, there are disadvantages of large heat and mass transfer resistance, difficult recovery, and easy environmental pollution caused by dust. Therefore, it is necessary to design a MOFs carrier strategy, i.e. the MOFs adsorbent and the carrier (substrate) are organically combined into a whole, called a bulk adsorbent, so as to effectively solve the above problems. Preparation techniques for porous adsorbent carriers have been widely reported, and mainly include dip coating and in-situ growth. The dip coating method is a method of immersing a carrier in a mixed solution containing an adsorbent and a binder to adhere the adsorbent to the surface of a substrate by utilizing the adhesive property of the binder. The method is simple and practical, but the existence of the binder reduces the loading rate of the adsorbent, and can block the pore passages of the adsorbent to reduce the adsorption performance. In contrast, the in situ growth method is highly practical. The MOF is uniformly and compactly distributed on the base material only by directly placing the base material in the reaction liquid and crystallizing at a certain temperature. And the gaps (pores) of the substrate can reduce the heat and mass transfer resistance of the adsorbent to the maximum extent. At present, the base materials for carrying the adsorbent mainly comprise inorganic ceramic fibers, glass fibers, cordierite and the like, and metal bases such as aluminum foils, copper foils and the like. For example, chinese patent application for a honeycomb ceramic-based aluminum-fumaric acid MOF adsorbent and an in-situ synthesis method thereof, and Chinese patent application for an aluminum foil-based aluminum-fumaric acid MOF adsorbent coating and a mixed solvent in-situ synthesis method and application thereof, the former adopts a honeycomb ceramic substrate, on one hand, the former can be manufactured by a special processing technology, and the aluminum-fumaric acid MOF adsorbent prepared by a hydrothermal in-situ synthesis technology has weak bonding force with the substrate, is easy to fall off powder and the like; the latter aluminum foil-based aluminum-fumaric acid MOF adsorbent adopts a mixed solvothermal scheme, and mainly has the defects of low adsorbent loading rate (below 40%), single-side coating and the like.
In view of the above, the present invention is directed to finding suitable substrates for carrying MOF-forming hygroscopic agents by in situ synthesis methods, which are capable of binding MOF-adsorbing agents tightly and achieving high loading on the substrate.
Disclosure of Invention
In order to overcome the defects of powder falling and low load rate of the moisture absorbent in the prior art, the invention aims to provide an organic foam-based MOF bulk moisture absorbent, a mixed solvent thermal in-situ synthesis method and application thereof. The invention takes hydrophilic organic high polymer foam (organic foam) with high porosity (not less than 95 percent) as a base material, and adopts a mixed solvothermal method to synthesize the organic foam-based MOF block moisture absorbent in situ.
The organic foam MOF block moisture absorbent synthesized in situ by mixed solvent heat provided by the invention has the characteristics of tight combination of base materials and MOF particles (no powder falling), high load rate (more than 70%), high adsorption amount of the MOF moisture absorbent under low humidity, low desorption temperature, good stability and the like.
The invention relates to a Metal Organic Framework (MOF) porous moisture absorbent, more precisely, MOF powder is carried and organic foam is used as a substrate, and a mixed solvent thermal process is adopted to synthesize an organic foam MOF bulk moisture absorbent in situ. The synthesized organic foam-based MOF block moisture absorbent can be used in the field of adsorption heat pumps to realize energy conservation of air conditioners.
The object of the present invention is achieved by the following means.
The invention provides a mixed solvent thermal in-situ synthesis method of an organic foam-based MOF block moisture absorbent, which comprises the following steps:
(1) Preparation of reaction solution: under the condition of stirring, mixing an organic dicarboxylic acid solution dissolved in DMF (N, N-dimethylformamide) and an aluminum salt solution dissolved in water, and stirring to obtain a uniform reaction solution;
(2) In-situ synthesis of a block moisture absorbent by solvent heating: adding the reaction liquid obtained in the step (1) into a reaction kettle with a polytetrafluoroethylene lining, completely immersing the organic foam block into the reaction liquid, and sealing the reaction kettle; and (3) reacting at the temperature of 90-130 ℃, naturally cooling after the reaction is finished, taking out the block, washing, drying and activating to obtain the organic foam MOF block moisture absorbent.
Preferably, the DMF of step (1) is reacted with water (H) 2 The volume ratio of O) is 1 (3-10).
Further preferably, DMF is capable of efficiently dissolving the organic dicarboxylic acid, and DMF and H are 2 O can be mutually dissolved, so that the organic dicarboxylic acid is uniformly dispersed in the reaction solution; the total amount of the fixed solvent, less DMF, poor solubility of the organic dicarboxylic acid and poor system dispersion; DMF poly, H 2 O is relatively less, the migration rate of aluminum ions to the foam base material is high, the acting force of the formed MOF and the base material is weak, and powder falling is easy; preferably DMF and water (H) 2 The volume ratio of O) is 1 (4-7).
Preferably, the organic dicarboxylic acid in the step (1) includes one of fumaric acid, 2, 5-furandicarboxylic acid, 3, 5-pyrazoledicarboxylic acid, isophthalic acid and 2, 5-pyrroledicarboxylic acid; in the step (1), the aluminum salt is one of water-soluble aluminum chloride, water-soluble aluminum sulfate, water-soluble aluminum nitrate and water-soluble aluminum acetate.
The MOF in the step (2) comprises Al-fumarate (A520), MIL-160 (Al), MOF-303, CAU-10-H6 and KMF-1 which are respectively formed by matching the organic dicarboxylic acid, namely fumaric acid, 2, 5-furandicarboxylic acid, 3, 5-pyrazoledicarboxylic acid, isophthalic acid and 2, 5-pyrroledicarboxylic acid, with aluminum salt.
Further preferably, the organic dicarboxylic acid is fumaric acid in consideration of the price of the organic dicarboxylic acid and the aluminum salt, the compatibility of the organic dicarboxylic acid and the aluminum salt with a solvent, the reaction difficulty and the like; the aluminum salt is aluminum sulfate, and MOF formed by matching fumaric acid and aluminum sulfate is Al-fumarate (A520).
Preferably, in the step (1), the molar ratio of the organic dicarboxylic acid to aluminum ions in the aluminum salt is (0.8-1.4): 1.
further preferably, the organic dicarboxylic acid is more, the system dispersibility is poor, and the MOF moisture absorbent loading rate is low; the organic dicarboxylic acid is less, the system is uniformly dispersed, and the MOF is tightly combined on the foam. The molar ratio of the organic dicarboxylic acid to the aluminum ions in the aluminum salt is preferably (0.9-1.2): 1.
preferably, the organic foam in step (2) includes more than one of hydrophilic Polyurethane (PU) foam, hydrophilic Melamine (MF) foam, and hydrophilic polyvinyl alcohol (PVA) foam.
Preferably, the porosity of the organic foam obtained in the step (2) is more than or equal to 95 percent.
Further preferably, hydrophilic polyurethane foam is preferred in view of mechanical strength, solvent resistance and the like of the organic foam.
Preferably, in the step (2), the reaction temperature in the reaction kettle is 90-120 ℃. The reaction temperature is low, the crystallization rate is slow, and the reaction time is long; the reaction activation energy is insufficient, uniform MOF growth is not facilitated, and the load rate is low; the reaction temperature is high, the reaction speed is high, and the formed crystal has defects; the formed crystals are dissolved reversely, so that the coating is not uniform and easy to fall off. Preferably, the temperature of the reaction in the reaction kettle is 100 to 120 ℃.
Preferably, in the step (2), the reaction time in the reaction kettle is 10-13h. The reaction time is short, the crystallization is incomplete, and the load rate is not high; if the time is too long, reverse dissolution is easy to occur, and crystals fall off. Preferably, the reaction time in the reaction kettle is 12h.
Preferably, the drying activation in the step (2) is carried out for 5 to 8 hours by blowing at the temperature of between 110 and 130 ℃.
Preferably, the drying activation in the step (2) is forced air drying at 120 ℃ for 6h.
The invention provides an organic foam-based MOF bulk moisture absorbent synthesized by the synthesis method.
The invention also provides application of the organic foam-based MOF bulk moisture absorbent in adsorption heat pump technology.
Preferably, the organic foam-based MOF bulk moisture absorbent acts as an adsorbent for adsorptive heat pump technology.
The invention provides a mixed solvent thermal in-situ synthesis method, which adopts hydrophilic organic foam as a base material to ensure that organic dicarboxylic acid and Al 3+ Can be smoothly coordinated on a substrate to form MOF crystal grains which are deposited on the surface of the substrate and a large number of pores, so that the substrate and the MOF crystal grains are tightly combined and are not easy to fall off. The organic foam-based MOF moisture absorbent is used as an integral moisture absorbent, effectively reduces the heat transfer and mass transfer resistance of the moisture absorbent, is easy to recycle MOF, and is applied to AHPs.
According to the invention, acetic acid is not added in the step of mixing the organic dicarboxylic acid solution dissolved in DMF with the aluminum salt solution dissolved in water and stirring to obtain a uniform reaction solution, because the addition of the acetic acid is found in the research to easily change the mechanical property of organic foam, the MOF is not fully grown on a carrier, and the growth of the hygroscopic agent can be more uniform without adding the acetic acid.
Compared with the prior art (dip coating/in-situ growth), the invention has the following advantages and beneficial effects:
(1) According to the mixed solvent in-situ thermal synthesis method provided by the invention, the prepared organic foam MOF block moisture absorbent has high mechanical property, the MOF and a base material have strong binding force, and the phenomenon of falling off is not easy to occur.
(2) According to the invention, the MOF block moisture absorbent is generated in situ, no additional adhesive is added, the porosity of the organic foam is high (more than 95%), and MOF crystal grains are uniformly distributed on the surface and in the pores of the foam, so that the MOF moisture absorbent generated in situ is high in loading amount (more than 70%), and a large number of pores exist in the organic foam, thereby being beneficial to reducing the heat and mass transfer resistance of the MOF moisture absorbent.
(3) Compared with MOF powder, the organic foam-based MOF bulk moisture absorbent prepared by the mixed solvent thermal in-situ synthesis method provided by the invention has lower desorption temperature.
(4) The organic foam-based MOF bulk moisture sorbents prepared in accordance with the present invention have a high water vapor sorption at low humidity (≦ 40% rh).
Description of the figures
Fig. 1 is an XRD spectrum of the moisture absorbents prepared in examples 1 to 3 and comparative example.
FIG. 2 is an SEM image of example 1 and a PU foam.
Fig. 3 is a graph showing the dynamic isothermal water vapor adsorption and desorption curves of the moisture absorbents prepared in example 1 and comparative example.
Fig. 4 is a graph showing 50 continuous water vapor adsorption and desorption cycles of the moisture absorbents prepared in example 1 and comparative example.
Detailed Description
The following description of the embodiments of the present invention is provided in connection with the accompanying drawings and examples, but the invention is not limited thereto. It is noted that the processes described below, if not specifically detailed, are all those that can be realized or understood by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer, and are considered to be conventional products available by commercial purchase.
Comparative example
(1) According to fumaric acid with Al 3+ The molar ratio of DMF to H is 1 2 O volume ratio 1; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 O solutionFormation of Al in 30mL deionized water 2 (SO 4 ) 3 The aqueous solution of (a); adding fumaric acid solution in DMF dropwise to Al 2 (SO 4 ) 3 The mixture was stirred for 10min to obtain a homogeneous reaction solution.
(2) And (2) adding the reaction solution prepared in the step (1) into a 100mL polytetrafluoroethylene lining reaction kettle, sealing, placing in a muffle furnace for reaction at 110 ℃ for 12h, and cooling to room temperature after the reaction is finished. And (3) centrifugally separating solids, centrifugally washing the solids for three times by using deionized water, and drying and activating the solids for 6 hours in a blast drying oven at 120 ℃ to obtain Al-fumarateMOF moisture absorbent powder.
Example 1
(1) According to fumaric acid with Al 3+ The molar ratio of DMF to H is 1 2 O volume ratio 1; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 Dissolving O in 30mL of deionized water to form Al 2 (SO 4 ) 3 The aqueous solution of (a); add fumaric acid in DMF dropwise to Al 2 (SO 4 ) 3 The mixture was stirred for 10min to obtain a homogeneous reaction solution.
(2) Adding the reaction liquid prepared in the step (1) into a 100mL polytetrafluoroethylene reaction kettle, completely immersing a polyurethane foam block with the size of 1cm multiplied by 0.5cm into the reaction liquid, sealing, placing the reaction liquid in a muffle furnace at 110 ℃ for reaction for 12h, cooling to room temperature after the reaction is finished, taking out the block, washing with deionized water for three times, and drying and activating at 120 ℃ in a blast drying oven for 6h to obtain the polyurethane foam Al-fumarateMOF block moisture absorbent.
Example 2
(1) According to fumaric acid with Al 3+ The molar ratio of DMF to H is 1 2 Dissolving 0.928g (8 mmol) of fumaric acid powder in 7mL of DMF in a 50mL beaker at room temperature under magnetic stirring in a volume ratio of O to 1 to form a DMF solution of fumaric acid; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 O dissolved in 28mL deionized water to form Al 2 (SO 4 ) 3 Is dissolved in waterLiquid; add fumaric acid in DMF dropwise to Al 2 (SO 4 ) 3 Stirring the aqueous solution for 10min to obtain a uniform reaction solution.
(2) Adding the reaction liquid prepared in the step (1) into a 100mL polytetrafluoroethylene reaction kettle, completely immersing a polyurethane foam block with the size of 1cm multiplied by 0.5cm into the reaction liquid, sealing, placing in a muffle furnace at 110 ℃ for reaction for 12h, cooling to room temperature after the reaction is finished, taking out the block, washing with deionized water for three times, and drying and activating at 120 ℃ in a blast drying oven for 6h to obtain the polyurethane foam Al-fumarateOF block moisture absorbent.
Example 3
(1) According to fumaric acid with Al 3+ 1, DMF to H 2 O volume ratio of 1; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 O dissolved in 30.625mL deionized water to form Al 2 (SO 4 ) 3 The aqueous solution of (a); adding fumaric acid solution in DMF dropwise to Al 2 (SO 4 ) 3 Stirring the aqueous solution for 10min to obtain a uniform reaction solution.
(2) Adding the reaction liquid prepared in the step (1) into a 100mL polytetrafluoroethylene reaction kettle, completely immersing a polyurethane foam block with the size of 1cm multiplied by 0.5cm into the reaction liquid, sealing, placing the reaction liquid in a muffle furnace at 110 ℃ for reaction for 12h, cooling to room temperature after the reaction is finished, taking out the block, washing with deionized water for three times, and drying and activating at 120 ℃ in a blast drying oven for 6h to obtain the polyurethane foam Al-fumarateMOF block moisture absorbent.
Example 4
(1) According to fumaric acid with Al 3+ 1, DMF to H 2 O volume ratio 1; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 Dissolving O in 30mL deionized water to form Al 2 (SO 4 ) 3 The aqueous solution of (a); adding fumaric acid solution in DMF dropwise to Al 2 (SO 4 ) 3 The mixture was stirred for 10min to obtain a homogeneous reaction solution.
(2) Adding the reaction liquid prepared in the step (1) into a 100mL polytetrafluoroethylene reaction kettle, completely immersing a polyurethane foam block with the size of 1cm multiplied by 0.5cm into the reaction liquid, sealing, placing the reaction liquid in a muffle furnace at 110 ℃ for reaction for 12h, cooling to room temperature after the reaction is finished, taking out the block, washing with deionized water for three times, and drying and activating at 120 ℃ in a blast drying oven for 6h to obtain the polyurethane foam Al-fumarateMOF block moisture absorbent.
Example 5
(1) According to fumaric acid with Al 3+ 1.2 molar ratio of DMF to H 2 O volume ratio of 1; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 Dissolving O in 30mL of deionized water to form Al 2 (SO 4 ) 3 An aqueous solution of (a); adding fumaric acid solution in DMF dropwise to Al 2 (SO 4 ) 3 The mixture was stirred for 10min to obtain a homogeneous reaction solution.
(2) Adding the reaction liquid prepared in the step (1) into a 100mL polytetrafluoroethylene reaction kettle, completely immersing a polyurethane foam block with the size of 1cm multiplied by 0.5cm into the reaction liquid, sealing, placing the reaction liquid in a muffle furnace at 110 ℃ for reaction for 12h, cooling to room temperature after the reaction is finished, taking out the block, washing with deionized water for three times, and drying and activating at 120 ℃ in a blast drying oven for 6h to obtain the polyurethane foam Al-fumarateMOF block moisture absorbent.
Example 6
(1) According to fumaric acid with Al 3+ The molar ratio of DMF to H is 1 2 Taking a 50mL beaker, dissolving 0.928g (8 mmol) of fumaric acid powder in 5mL of DMF under magnetic stirring at room temperature under the condition that the volume ratio of O is 1; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 Dissolving O in 30mL of deionized water to form Al 2 (SO 4 ) 3 An aqueous solution of (a); add fumaric acid in DMF dropwise to Al 2 (SO 4 ) 3 The mixture was stirred for 10min to obtain a homogeneous reaction solution.
(2) Adding the reaction liquid prepared in the step (1) into a 100mL polytetrafluoroethylene reaction kettle, completely immersing a polyurethane foam block with the size of 1cm multiplied by 0.5cm into the reaction liquid, sealing, placing the reaction liquid in a muffle furnace at 90 ℃ for reaction for 12h, cooling to room temperature after the reaction is finished, taking out the block, washing with deionized water for three times, and drying and activating at 120 ℃ in a blast drying oven for 6h to obtain the polyurethane foam Al-fumarateMOF block moisture absorbent.
Example 7
(1) According to fumaric acid with Al 3+ 1, DMF to H 2 O volume ratio 1; another 50mL beaker was charged with 2.66g (4 mmol) of Al 2 (SO 4 ) 3 ·18H 2 Dissolving O in 30mL deionized water to form Al 2 (SO 4 ) 3 An aqueous solution of (a); add fumaric acid in DMF dropwise to Al 2 (SO 4 ) 3 The mixture was stirred for 10min to obtain a homogeneous reaction solution.
(2) Adding the reaction liquid prepared in the step (1) into a 100mL polytetrafluoroethylene reaction kettle, completely immersing a polyurethane foam block with the size of 1cm multiplied by 0.5cm into the reaction liquid, sealing, placing in a muffle furnace at 120 ℃ for reaction for 12h, cooling to room temperature after the reaction is finished, taking out the block, washing with deionized water for three times, and drying and activating at 120 ℃ in a blast drying oven for 6h to obtain the polyurethane foam Al-fumarateOF block moisture absorbent.
Test conditions and methods
Load factor calculation for bulk moisture absorber (example):
let the mass of the polyurethane foam not loaded with Al-fumarateMOF be m 1 And after the reaction is finished and the drying is carried out, the total mass of the obtained polyurethane foam-based Al-fumarateMOF block moisture absorbent is m 2 Negative of polyurethane foam based Al-fumarateMOF block moisture absorbentThe loading rate a can be expressed as:
x-ray diffraction analysis
Grinding the prepared bulk moisture absorbent into a powder sample, and performing crystal phase analysis on the sample by adopting a full-automatic X-ray powder diffractometer (XRD) with the model of D8Advance of Germany Bruker company; the test conditions were a Cu target, the diffraction angle range was 5-60 °, the scan rate was 0.1 sec/step, and the step size was 0.02 °.
Scanning Electron Microscope (SEM)
The surface morphology of the bulk moisture absorbent sample was observed using a Scanning Electron Microscope (SEM) model SU8220 from Hitachi corporation, japan. The scanning voltage is 5kV, and the surface of the sample is sprayed with gold before testing.
Dynamic isothermal water vapor adsorption curve:
the test adopts a gravimetric dynamic adsorption analyzer with the model of AQUADYNEDVS of Quantachrome instruments of America to analyze the adsorption and desorption performances of the block moisture absorbent and the powder Al-fumarate. Differential thermogravimetric analysis (DTG) analysis:
the desorption properties of the samples were tested using a TG209F3 thermogravimetric analyzer (TG) from Netzsch, germany. The temperature rising rates of the desorption program are respectively 4 ℃/min, 6 ℃/min, 8 ℃/min, 10 ℃/min and 12 ℃/min, and the temperature is raised from the room temperature to 150 ℃. Before measurement, the sample is heated to 120 ℃ to remove moisture and impurities, then cooled to 25 ℃ and saturated with water vapor at a relative humidity of 60%. The measured mass of the sample was 10mg. Calculating the Desorption activation energy (E) according to the Cinge equation d )。
Wherein Ed is desorption activation energy and has a unit of kJ. Mol- 1 (ii) a R is a gas constant, 8.314J/(mol.K); t represents the desorption temperature (K); beta is the rate of temperature rise (K/min), and K is a constant.
Analysis of cycling stability
The cycle stability test is divided into two parts of adsorption and desorption, and firstly, a dry sample (about 100 mg) is weighed to have the mass M 1 Placing in a constant temperature and humidity cabinet, weighing the mass M after reaching adsorption saturation in an RH (relative humidity) environment of 25 ℃ and 60% 2 And then transferring the sample after moisture absorption to a blast drying oven to be dried for 6h at 120 ℃ for moisture removal, and repeating moisture absorption and moisture removal, wherein an average value is taken every 5 times of circulation, and the circulation is performed for 50 times in total.
The water vapor adsorption amount R of the moisture absorbent can be expressed as
R＝(M 2 -M 1 )/M 1 (3)
Fig. 1 is an XRD spectrum of the moisture absorbents prepared in examples 1 to 3 and comparative example. As can be seen from fig. 1, XRD diffraction peak shapes and peak positions of the mixed solvent hot in-situ synthesized polyurethane foam-based Al-fumarateMOF bulk moisture absorbents (examples 1 to 3) were consistent with Al-fumarateMOF moisture absorbent powders (comparative example), demonstrating that the Al-fumarateMOF bulk moisture absorbents can be successfully prepared in situ on Polyurethane (PU) foam substrates using the mixed solvent hot method.
FIG. 2 is an SEM image of a polyurethane foam based Al-fumarateMOF bulk moisture absorber and Polyurethane (PU) foam prepared in example 1. As can be seen from FIG. 2, a great deal of pores exist in the polyurethane foam as a carrier, al-fumarateOF grows perfectly in the pore structure of the polyurethane foam substrate, al-fumarateOF crystals are in a cauliflower-shaped structure and grow regularly and uniformly in an arrayed manner, and the substrate and MOF crystal grains are tightly combined without a shedding phenomenon.
Fig. 3 is a graph showing the dynamic isothermal water vapor adsorption and desorption curves of the moisture absorbents prepared in example 1 and comparative example. As can be seen from the dynamic adsorption and desorption curves, the polyurethane foam-based Al-fumarateMOF bulk moisture absorbent (example 1) and Al-fumarateMOF moisture absorbent powder (comparative example) both maintain consistent adsorption and desorption behaviors, and have higher adsorption rate and moisture absorption performance under low humidity conditions (40% RH or less). As can also be seen from FIG. 3, the adsorption amount of Al-fumarateMOF moisture absorbent powder (comparative example) was 338mg/g and that of polyurethane foam Al-fumarate bulk moisture absorbent (example 1) was 303mg/g, which is higher than the theoretical adsorption amount of 241.9mg/g, at 30% RH, because the moisture absorption property of the polyurethane foam Al-fumarate bulk moisture absorbent (example 1) was maintained due to the hydrophilicity of the PU foam substrate.
Fig. 4 is a graph showing 50 continuous water vapor adsorption and desorption cycles of the moisture absorbent prepared in comparative example of example 1. As can be seen from FIG. 4, after continuous water vapor adsorption-desorption cycles, no significant loss of saturated adsorption capacity exists in both, which indicates that the polyurethane foam based Al-fumarateOF block moisture absorbent prepared in situ by mixed solvent heat has excellent cycle stability.
TABLE 1
Table 1 shows the loading ratios of the polyurethane foam-based Al-fumarateMOF bulk moisture absorbents prepared in examples 1 to 7. It can be obviously seen that the load ratios of the polyurethane foam-based Al-fumarateMOF bulk moisture absorbents synthesized in situ by the mixed solvent thermal method are all higher (> 70%).
TABLE 2
Table 2 shows desorption temperatures (T) and desorption activation energies (E) of the moisture absorbents prepared in example 1 and comparative example at different temperature increasing rates d ). By comparison, the desorption temperature of the polyurethane foam Al-fumarateOF block moisture absorbent (example 1) is far lower than that of Al-fumarateOF moisture absorbent powder (comparative example) under the same temperature rising rate, which shows that the polyurethane foam substrate can effectively improve the heat and mass transfer rate of the moisture absorbent. The desorption activation energies of the polyurethane foam-based Al-fumarateOF bulk moisture absorbent (example 1) and Al-fumarateOF moisture absorbent powder (comparative example) are respectively 51.68kJ/mol and 66.6kJ/mol according to the calculation of Kissinger equation, which shows that the former can realize energy-saving desorption, and further shows that the Al-fumarateOF carrier is an effective way for realizing energy-saving desorption.
The above examples are only preferred embodiments of the present invention, which are intended to be illustrative and not limiting, and those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention.
Claims (10)
1. A mixed solvent thermal in-situ synthesis method of an organic foam-based MOF block moisture absorbent is characterized by comprising the following specific steps:
(1) Preparation of reaction solution: under the condition of stirring, mixing an organic dicarboxylic acid solution dissolved in DMF with an aluminum salt solution dissolved in water, and stirring to obtain a uniform reaction solution;
(2) In-situ synthesis of a block moisture absorbent by solvent heating: and (2) immersing the organic foam block in the reaction liquid prepared in the step (1) for heating reaction, cooling after the reaction is finished, taking out the block, washing, drying and activating to obtain the organic foam MOF block moisture absorbent.
2. The method for the mixed solvent thermal in-situ synthesis of the organic foam-based MOF bulk moisture absorbent according to claim 1, wherein the volume ratio of DMF to water in the step (1) is 1 (3-10).
3. The method for the mixed solvent thermal in-situ synthesis of the organic foam-based MOF bulk moisture absorbent according to claim 1, wherein the organic dicarboxylic acid of step (1) comprises one of fumaric acid, 2, 5-furandicarboxylic acid, 3, 5-pyrazoledicarboxylic acid, isophthalic acid and 2, 5-pyrroledicarboxylic acid.
4. The method for the mixed solvent thermal in-situ synthesis of the organic foam-based MOF bulk moisture absorbent according to claim 1, wherein the aluminum salt in step (1) is one of aluminum chloride, aluminum sulfate, aluminum nitrate and aluminum acetate.
5. The method for the mixed solvent thermal in-situ synthesis of the organic foam-based MOF bulk moisture absorbent according to claim 1, wherein the molar ratio of the organic dicarboxylic acid to aluminum ions in the aluminum salt in the step (1) is (0.8-1.4): 1.
6. The method for the mixed solvent thermal in-situ synthesis of the organic foam-based MOF bulk moisture absorbent according to claim 1, wherein the organic foam in the step (2) comprises one or more of polyurethane, melamine and polyvinyl alcohol.
7. The method for the mixed solvent thermal in-situ synthesis of the organic foam-based MOF bulk moisture absorbent according to claim 1, wherein the heating reaction in the step (2) is 90-130 ℃ for 10-13h.
8. The method for the mixed solvent thermal in-situ synthesis of the organic foam MOF bulk moisture absorbent according to claim 1, wherein the drying activation in the step (2) is 110-130 ℃ air drying for 5-8h.
9. An organic foam-based MOF bulk moisture absorbent synthesized by the mixed solvent thermal in-situ synthesis method of any one of claims 1 to 8.
10. Use of the organic foam-based MOF bulk moisture absorber of claim 9 in adsorption heat pump technology.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211656651.7A CN115975369A (en) | 2022-12-22 | 2022-12-22 | Organic foam-based MOF (metal organic framework) block moisture absorbent, and thermal in-situ synthesis method and application of mixed solvent thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211656651.7A CN115975369A (en) | 2022-12-22 | 2022-12-22 | Organic foam-based MOF (metal organic framework) block moisture absorbent, and thermal in-situ synthesis method and application of mixed solvent thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115975369A true CN115975369A (en) | 2023-04-18 |
Family
ID=85973420
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211656651.7A Pending CN115975369A (en) | 2022-12-22 | 2022-12-22 | Organic foam-based MOF (metal organic framework) block moisture absorbent, and thermal in-situ synthesis method and application of mixed solvent thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115975369A (en) |
-
2022
- 2022-12-22 CN CN202211656651.7A patent/CN115975369A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101721556B1 (en) | Adsorbents comprising organic-inorganic hybrid nanoporous materials for sorption of water or alcohol and use thereof | |
| CN112915969B (en) | Metal organic framework/halide composite ammonia adsorbent and preparation method thereof | |
| CN108404868B (en) | Based on doping of NH by alkali metal cations2-MIL-125(Ti) material and preparation method thereof | |
| CN112755965B (en) | Preparation method of composite dehumidification adsorbent paper sheet made of MOF material and lithium chloride | |
| Chen et al. | Experimental investigation of the dehumidification performance of a metal-organic framework MIL-101 (Cr)/ceramic fibre paper for use as a desiccant wheel | |
| CN112844326B (en) | Magneto-thermal composite material, preparation method and application thereof | |
| CN113231009B (en) | Ammonia adsorbent and preparation method thereof | |
| CN110787584A (en) | Application of cerium-based metal organic framework structure material in CO2Adsorption separation application of | |
| CN111375385A (en) | Preparation method and application of bimetallic organic framework adsorbent | |
| CN113736432B (en) | Metal oxide heat storage material, metal oxide heat storage unit and preparation method | |
| CN109192526A (en) | A kind of porous carbon/metal oxide sandwich and its preparation method and application | |
| CN105617978B (en) | Room temperature CO absorption2Support type MgO/ γ-Al2O3The preparation method of adsorbent | |
| CN110975817B (en) | Aluminum foil-based aluminum-fumaric acid MOF adsorbent coating and mixed solvent in-situ synthesis method and application thereof | |
| CN113371730A (en) | Modified calcium low-silicon zeolite molecular sieve and preparation method thereof | |
| Bonaccorsi et al. | Synthesis of SAPO-34/graphite composites for low temperature heat adsorption pumps | |
| CN115975369A (en) | Organic foam-based MOF (metal organic framework) block moisture absorbent, and thermal in-situ synthesis method and application of mixed solvent thereof | |
| CN111978922B (en) | Hydrated salt-based medium-low temperature chemical heat storage material and preparation method thereof | |
| Tan et al. | A solar-driven adsorbent based on Al-fumarate metal-organic framework coating with high water cycle efficiency | |
| CN117225376A (en) | Porous solid adsorbent for carbon dioxide and preparation method thereof | |
| CN108607512B (en) | Method for modifying MOF material by molybdenum-based sulfide | |
| CN107088401B (en) | Rapid CO production using ionic liquid additives2Method for producing adsorbent | |
| KR20160033644A (en) | Uses of mof in an adsorption cooling/heating system | |
| WO2022088675A1 (en) | Carbon dioxide adsorbent, and preparation method and use method therefor | |
| CN113617327B (en) | Synthesis method of nano single crystal manganese lithium adsorbent | |
| CN111617806B (en) | g-C with sodium citrate as matrix 3 N 4 MOFs composite photocatalytic material and preparation method and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |