CN109967038B

CN109967038B - Ce-MOFs material for adsorbing VOCs released in wood drying process and use method

Info

Publication number: CN109967038B
Application number: CN201910098611.7A
Authority: CN
Inventors: 张晓涛; 贺勤; 王霞; 李淑静; 于建芳; 李丽丽; 王哲; 姚利宏; 王雅梅; 郝一男; 王喜明
Original assignee: Inner Mongolia Agricultural University
Current assignee: Inner Mongolia Agricultural University
Priority date: 2019-01-31
Filing date: 2019-01-31
Publication date: 2021-10-01
Anticipated expiration: 2039-01-31
Also published as: CN109967038A

Abstract

The invention discloses a Ce-MOFs material for adsorbing VOCs released in a wood drying process and a using method thereof. methyl-alpha-D-galactopyranoside and phthalic anhydride are used as two ligand raw materials, serrated methyl-alpha-D-galactopyranoside aromatic acid ester (GBE) with coordination capacity is synthesized under the catalytic action of DIEA to serve as an organic ligand for constructing the MOFs adsorbing material, and then the GBE and a rare earth metal cerous nitrate solution are subjected to self-assembly coordination to synthesize the Ce-MOFs benzene adsorbing material. The Ce-MOFs material for adsorbing VOCs released in the wood drying process provided by the invention has the advantages of large adsorption capacity, good adsorption effect, strong adsorption capacity for benzene which is a specific VOCs gas pollutant released in the wood high/normal temperature drying, wide raw material source, no toxicity, no harm, low recovery cost, capability of being recycled for multiple times, simplicity and convenience in operation, stable structure, no secondary environmental pollution and the like, and has good application prospect in the wood drying industrial process.

Description

Ce-MOFs material for adsorbing VOCs released in wood drying process and use method

Technical Field

The invention belongs to the technical field of adsorption materials, and particularly relates to a Ce-MOFs material for adsorbing VOCs released in a wood drying process and a using method thereof.

Background

Volatile Organic Compounds (VOCs) are volatile organic compounds having a boiling point of less than 260 ℃ and a saturated vapor pressure of more than 133.322Pa at normal temperature and pressure. VOCs are organic gaseous pollutants with strong volatility, special irritation, toxicity and harm, and some of the VOCs have been listed as carcinogens, such as vinyl chloride, benzene, polycyclic aromatic hydrocarbons, and the like. The harm of VOCs to the atmospheric environment is mainly that the VOCs promote the formation of ozone photochemical oxidants and generate secondary pollution to the atmospheric environment, and when the VOCs in the air reach a certain concentration, people can feel symptoms such as headache and vomit, and respiratory disturbance and respiratory system diseases of the human body are caused, and people can die when the symptoms are serious.

Different types of Volatile Organic Compounds (VOCs) can be generated by drying wood, although the amount of gas generated in the process is not large, the harm of the VOCs to human beings and the environment is more and more emphasized along with the enhancement of the environmental awareness of people, and the research on the application of an adsorption technology to the treatment of the VOCs is one of the hot problems of the current environmental pollution treatment. From the research on wood drying at home and abroad, it is found that the VOCs generated in the wood drying process are roughly divided into two categories of terpenoids and non-terpene volatiles. Volatile substances other than terpenes are often harmful gases such as aldehydes, benzene, acids, etc. Some of which are inherent in wood and others are formed byGenerated by chemical reaction. Table 1 shows the release of major VOCs in the wood drying industry. As shown in Table 1, the benzene content was highest (39.023 mg/m) among the VOCs released by the high/ambient drying industry³) Therefore, a suitable method for purifying benzene in VOCs needs to be found.

TABLE 1 Release of part of VOCs in Wood drying

Benzene (C)₆H₆) The regular hexagon structure is aromatic hydrocarbon with the simplest composition structure, is colorless, sweet and oily transparent liquid at normal temperature and normal pressure, has the density less than that of water and strong aromatic smell, and chemical bonds between carbon and carbon in six-membered rings are between single bonds and double bonds and are called large pi bonds. Benzene is flammable, toxic, and is listed as the first carcinogen in IARC. Benzene is characterized by easy volatilization, flammability, easy explosion of vapor and the like. Benzene is insoluble in water, can be mixed with ethanol, diethyl ether, acetone, carbon tetrachloride, carbon disulfide and glacial acetic acid, and can be used as an organic solvent. The melting point of benzene was 5.5 ℃, the boiling point was 80.1 ℃, the relative molecular mass was 78.11g/mol, the relative density was 0.8786g/mL, and the vapor density was 2.77 g/L. Benzene has great toxicity to human body, typical carcinogenic teratogenicity and mutagenicity, and can cause genetic material damage of human and animal. After a person inhales high-concentration benzene vapor, central nervous system anesthesia can occur, light people have dizziness, headache, nausea, chest distress, hypodynamia and vague consciousness, and severe people can cause aplastic anemia and leukemia to die.

VOCs has great harm to human bodies and the environment, and the purification treatment of the VOCs in the exhaust gas discharged in the wood drying industry is very important. Common purification methods are: the method comprises a combustion method, a condensation method, an absorption method, a catalysis method, a biodegradation method and a low-temperature plasma technology, wherein the methods have good treatment effects on VOCs gas to a certain extent, but have certain disadvantages. If the cost of the absorption technology is high, the operation process is complex; the condensation technology is not suitable for toxic gas with low concentration, can not be used independently, and is often used for assisting other technologies; membrane separation technology is a selective permeation technology that is not suitable for all gases because not all gases can pass through the membrane element; the direct combustion destruction technology can only aim at a part of gas with higher concentration, but can not directly combust gas with low concentration, and in the combustion process, the combustion temperature needs to be kept about 1000 ℃, so that the energy consumption is higher; the photocatalytic degradation technology, whether the secondary pollution is caused in the catalytic process or not, is not yet determined and is not mature; the biodegradation technology mainly aims at a part of VOCs gas with low concentration, and for VOCs gas with high concentration, the degradation difficulty is high and the degradation effect is not ideal. At present, the adsorption method is widely applied to treatment of VOCs in the wood drying process, and has good environmental and economic benefits due to the advantages of high removal efficiency, thorough purification, low energy consumption, mature process, recyclability, easy popularization and the like. The adsorption method is to treat gaseous polluted VOCs by using porous solid adsorbents, and select different adsorbents to have different adsorption effects on different gas molecules in the VOCs. The documents report active carbon, modified active carbon, molecular sieve, montmorillonite-based mesoporous material and the like, and the adsorption materials all have certain defects and limitations in the use process. For example, activated carbon is easy to desorb in a high-temperature environment, the recycling rate is low, the use cost is high, and the like; zeolite molecular sieve, which can not be used for adsorption under strong inorganic acid and strong alkali conditions; the pH value of the solution needs to be strictly controlled in the process of chemically modifying the surface of the montmorillonite, so that various factors are easy to change, and the adsorption performance of the montmorillonite is reduced. Benzene gas differs from conventional atmospheric VOCs gas in that there are two key points in the adsorption process with benzene gas molecules with the adsorbent: 1. benzene has a special spatial annular structure, and the adsorbing material is required to have a large number of pore diameters and pore volume structures which are similar to the molecular volume of benzene so as to enhance the physical adsorption effect on benzene gas; 2. because high-density electron cloud distribution exists above and below the benzene molecule closed conjugated six-membered ring, the benzene molecule closed conjugated six-membered ring can be more easily combined with an adsorption center with positive charges, and the chemical adsorption efficiency of the benzene molecule can be enhanced to a great extent. However, the conventional adsorbing materials do not have these two advantages.

The MOFs material is formed by combining metal ions and organic ligands, is a novel multifunctional crystal adsorption material, has the characteristics of a special topological structure, a pore channel with a specific size and a specific shape and the like, has a wide application prospect in the field of adsorption, and is paid attention to by researchers. Different adsorption effects on different kinds of VOCs are achieved, wherein the MOFs material has obvious adsorption effects on aldehydes, organic acids, alcohols and other substances, and for example, the IRMOF material combined by the Yaghi project has good adsorption effects on formaldehyde, methane and toluene; research on n-hexane, toluene, methanol, butanone, dichloromethane, n-butylamine and inorganic gases (CO) was conducted on the MILs series material combined by Ferey project of university of Versailles, France₂) The adsorption effect of (1). The adsorption of the MOFs material to organic gases is not only related to the pore structure of the MOFs material, but also related to pressure and a combination mode (hydrogen bond, supramolecular action and the like) in an adsorption process. The application mainly takes benzene of a special closed ring-shaped conjugated system as a research object to prepare the novel intelligent rare earth metal-organic framework Ce-MOFs adsorbing material.

Disclosure of Invention

The invention aims to provide a metal-organic framework Ce-MOFs adsorbing material taking rare earth metal cerium ions as central ions, which is used for adsorbing VOCs released in a wood high/normal temperature drying process and particularly has an obvious benzene adsorbing effect.

The Ce-MOFs material for adsorbing VOCs released in the wood drying process is characterized by being obtained by carrying out molecular rearrangement and self-assembly on serrated methyl-alpha-D-galactopyranoside aromatic acid ester with coordination capacity and a cerium nitrate solution.

Preferably, Ce³⁺The molar ratio of the aromatic acid ester of the serrated methyl-alpha-D-galactopyranoside ranges from 1: 1-5.

Preferably, the serrated methyl-alpha-D-galactopyranoside aromatic acid ester with coordination capacity is synthesized by methyl-alpha-D-galactopyranoside and phthalic anhydride under the catalysis of DIEA.

Preferably, the molar ratio of methyl-alpha-D-galactopyranoside to phthalic anhydride in DIEA is in the range of 1: 1-5.

Preferably, the serrated methyl-alpha-D-galactopyranoside aromatic ester with coordination capability is synthesized by methyl-alpha-D-galactopyranoside and phthalic anhydride under the catalysis of DIEA for 8-9 hours.

Preferably, Ce³⁺The molar ratio of the aromatic acid ester to the serrated methyl-alpha-D-galactopyranoside is 1: 3.

preferably, the molar ratio of methyl-alpha-D-galactopyranoside to phthalic anhydride in DIEA is 1: 3.

Preferably, the jagged methyl-alpha-D-galactopyranoside aromatic ester with coordination capability is synthesized by methyl-alpha-D-galactopyranoside and phthalic anhydride under the catalysis of DIEA for 8 hours.

A method for using Ce-MOFs material for adsorbing VOCs released in the drying process of wood comprises the step of measuring the relative partial pressure (P/P) of gas in the adsorption process₀) And is controlled in the range of 0.60 to 0.95.

Preferably, the relative partial pressures of the gases in the adsorption process (P/P)₀) The control is at 0.90.

The organic ligand GBE containing ester carbonyl sugar ring is prepared from phthalic anhydride and methyl-alpha-D-galactopyranoside, wherein the phthalic anhydride contains benzene ring, the methyl-alpha-D-galactopyranoside is a unique cyclic tetrahydroxy polyol and acetal structure, the hydroxyl on the ring is easy to react with carboxylic acid or anhydride substances, and the combination of the two increases the space structure of the three-dimensional skeleton of the ligand; and the lone pair electrons in the GBE ester carbonyl group are easy to mutually combine with the empty orbit of the rare earth metal ions by acting forces such as coordination bond, electrostatic attraction and the like to form a hinge type hole-shaped framework structure, and the hole framework of the special topological structure is larger and has a larger molar volume of 89.16cm³Per mol) gas volume size is identical, and the ligand skeleton of the adsorbent has a large number of ester groups, carboxyl groups, carbonyl groups and the like, so that the types of active functional groups and effective adsorption sites are increased, and the benzene structureThe material contains a special annular closed conjugated system, has large pi bonds of full delocalized flowable six-center six electrons, and can be filled with delocalized pi electrons when being adsorbed with a Ce-MOFs adsorbing material with an empty orbit³⁺[Xe]4f¹5d⁰6s⁰([Xe]4f¹5d¹6s²) Certain coordination bonding effect occurs in the empty 5d and 6s orbits and the rest empty 4f orbits, so that the Ce-MOF adsorbing material has obvious effect on adsorbing benzene which is a specific VOCs gas in wood drying.

In addition, the Ce-MOFs material for adsorbing VOCs released in the wood drying process provided by the invention has the advantages of large adsorption capacity, good adsorption effect, strong adsorption capacity for benzene which is one of specific VOCs gas pollutants released in wood high/normal temperature drying, wide raw material source, no toxicity, no harm, low recovery cost, capability of being recycled for multiple times, simplicity and convenience in operation, stable structure, no secondary environmental pollution and the like, and has good application prospect in the wood drying industrial process.

Drawings

FIG. 1 is a flow chart of the preparation experiment and the test experiment of the present invention.

FIG. 2 is a schematic molecular structure diagram of methyl-alpha-D-galactopyranoside aromatic acid ester, wherein, in a to c, the different molar ratios of methyl-alpha-D-galactopyranoside and phthalic anhydride are 1:1,1: 2,1: 3.

FIG. 3 is a structural simulation diagram of the Ce-MOFs adsorbent material.

FIG. 4 is an infrared spectrum of ligand GBE and Ce-MOFs adsorbing materials, curve a represents ligand GBE, and curve b represents Ce-MOFs.

FIG. 5 is an EDS diagram of a Ce-MOFs adsorbent material.

FIG. 6(a) shows N of Ce-MOFs adsorbent material₂And (b) is a pore size distribution curve of the Ce-MOFs adsorbing material.

FIG. 7 is an SEM image of a Ce-MOFs adsorbent material.

FIG. 8 is a TGA graph of Ce-MOFs adsorbent materials.

FIG. 9 is an XRD pattern of the Ce-MOFs adsorbent material.

FIG. 10 is a graph showing the effect of GBE production time on benzene adsorption.

FIG. 11 is a graph showing the effect of the feed ratio of two feedstocks on benzene adsorption for GBE preparation.

FIG. 12 is Ce³⁺Graph of the effect of molar ratio to GBE on benzene adsorption.

FIG. 13 is a graph showing the effect of the Ce-MOFs adsorbent on the adsorption amount of β -pinene.

FIG. 14 is a graph showing the influence of the Ce-MOFs-adsorbing material on the amount of carbon tetrachloride adsorbed.

FIG. 15 is a graph showing the effect of Ce-MOFs adsorbent material on the adsorption amount of alpha-pinene.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following will describe in detail a rare earth Ce-MOFs material for adsorbing benzene released from high temperature drying of wood provided by the present invention with reference to the examples. The following examples are intended to illustrate the invention only and are not intended to limit the scope of the invention.

The adsorbing material provided by the invention is made of metal Ce³⁺GBE is connected with GBE through coordination or chelation acting force, electrostatic attraction and the like, the Ce-MOFs adsorbing material is synthesized by molecular rearrangement and coordination self-assembly, wherein the GBE structure contains benzene ring, polyhydroxy six-membered ring and other structures and rare earth metal Ce³⁺([Xe]4f¹5d⁰6s⁰){La[Xe]4f¹5d¹6s²The empty orbits 5d and 6s of the new Ce-MOFs material structure have typical topological structures rich in a large number of mesopores and multiple pores, and the adsorption molar volume is most favorably 89.16cm³Benzene gas per mol, and excellent adsorption performance.

FIG. 2 is a structural simulation diagram of GBE as an organic ligand, namely a complex unit structure formed by connecting two molecules of methyl-alpha-D-galactopyranoside and phthalic anhydride at a molar ratio of 1:1 (FIG. 2a), 1:2 (FIG. 2b) and 1:3 (FIG. 2c), and FIG. 3 is a structural diagram of a simulated molecule of the Ce-MOFs adsorbent material.

1. Preparation of ligand GBE: 11.5g phthalic anhydride was weighed into a flat bottom flask and 50mL was addedMagnetically stirring acetone solution, stirring at 46 deg.C to dissolve completely, adding 5g methyl-alpha-D-galactopyranoside, heating to 65 deg.C, adding 5mL catalyst DIEA, mixing the solutions, heating and stirring for reflux reaction for 8 hr, cooling the obtained liquid to room temperature, and adding appropriate amount of P₂O₅Drying, filtering, and evaporating the obtained filtrate at 60 deg.C to remove acetone solvent to obtain viscous colorless liquid, i.e. organic ligand methyl-alpha-D-galactopyranoside aromatic acid ester (GBE). The obtained product is checked by thin layer chromatography, and developing agent is ethyl acetate and cyclohexane (V)_{Acetic acid ethyl ester}:V_Cyclohexane1:9) to verify that the product contains no unreacted phthalic anhydride.

2. Ce-MOFs materials: adopting a conventional solvent method, accurately weighing 6.25g of GBE, placing the GBE in a conical flask, adding 20mL of acetone to fully dissolve the GBE, and weighing 2.10g of cerium Ce Nitrate (NO)₃)₃·6H₂Dissolving O in 10mL of deionized water, and respectively measuring 10mLGBE solution and Ce³⁺Adding the solution into a conical flask, stirring and mixing uniformly, dropwise adding DIEA to adjust the pH value (about pH 7.00), stirring and reacting for 4 hours at room temperature, carrying out suction filtration on the mixed solution, washing the obtained solid with deionized water and acetone for several times, and drying in vacuum at 60 ℃ to constant weight.

3. Ce-MOFs adsorption experiment: weighing 0.2000g of Ce-MOFs test sample, putting the test sample into a sample tube of a test chamber of an adsorption apparatus (3H-2000PW, multi-station gravimetric steam adsorption apparatus, Bechard apparatus science and technology Limited, Beijing), heating and degassing in vacuum, weighing the sample Ce-MOFs to constant weight, evaporating adsorbate benzene vapor to a sample chamber from a liquid sample in a reagent tube, stabilizing the benzene vapor under a certain partial pressure, measuring the weight change of the sample at different times, and calculating the adsorption quantity, wherein the temperature of the test chamber is constant at 25 ℃ during testing.

4. Ce-MOFs desorption experiment: the desorption process is just opposite to the adsorption process, and the desorption process is that after the relative partial pressure of gas in the adsorption process reaches 0.90, the benzene gas in the adsorption container is pumped out by a vacuum pump so as to reduce the partial pressure of the gas in the container, and then the adsorption capacity is also reduced. When the partial pressure of benzene gas is reduced to a certain degree, the adsorption quantity at the moment is tested by a weighing method, namely the desorption quantity of the benzene gas by the Ce-MOFs adsorption material.

FIG. 4 shows the IR spectra of organic ligand GBE (a) and Ce-MOFs adsorbent material (b). As can be seen from a, GBE is 3401cm^-1Broad and strong peaks ascribed to incompletely reacted hydroxyl groups or free hydroxyl group peaks and hydrogen bonds on the methyl-alpha-D-galactopyranoside molecule; 2977cm^-1In the form of a methyl-CH on the aromatic ring of phthalic anhydride₃or-CH₂C-H absorption peak above; 1702cm^-1Is the characteristic absorption peak of carbonyl; 1579cm^-1、1561cm^-1、1487 cm^-1And 1445cm^-1All correspond to characteristic absorption peaks of the benzene ring; 1290cm^-1Is the bending vibration absorption peak of C-O in the carboxyl structure; at 1075cm^-1And 1044cm^-1The double shoulder peak is the characteristic absorption peak of the sugar ring. Compared with the infrared spectrum of the ligand GBE, the characteristic absorption peak of the carbonyl in the Ce-MOFs adsorbing material (b) is red-shifted to 1718cm^-1The absorption peak is almost completely inhibited, which shows that carbonyl participates in the reaction in the molecular rearrangement and self-assembly coordination process, and rare earth metal Ce³⁺Successfully coordinates with organic ligand GBE.

FIG. 5 is an EDS energy spectrum of the Ce-MOFs adsorbing material. As can be seen from the figure, the Ce-MOFs adsorbent mainly contains six elements of C, N, O, Ce, Zr and Al, wherein N, O and Ce are elements contained in the cerium nitrate solution, and it can be further demonstrated that-C ═ O and Ce³⁺Self-assembly coordination reaction occurs, C and O are elements contained in methyl-alpha-D-galactopyranoside and phthalic anhydride, and Zr and Al are impurities in the sample measurement and preparation process.

FIGS. 6a and 6b and Table 2 show the N content of the Ce-MOFs adsorbent material₂Adsorption-desorption curves, pore size distribution curves and related parameters. As can be seen in FIG. 6a, N₂An adsorption-desorption isothermal curve has a relatively obvious hysteresis loop, which shows that a large number of mesoporous and microporous structures exist in the Ce-MOFs adsorption material, and the curve conforms to a composite IV-type isothermal line of the adsorption-desorption isothermal curve, so that the adsorption of gas is facilitated. When relative pressure (P/P)₀) When the adsorption amount reaches 0.70, the adsorbate generates a capillary condensation phenomenon in the mesopores, and the adsorption amount rises steeply. Gas in low partial pressure regionThe body also has partial adsorption effect, which shows that the Ce-MOFs adsorption material and N₂Has stronger adsorption effect. FIG. 6b is a pore distribution curve of the Ce-MOFs adsorbent material, from which it can be seen that the pores of the Ce-MOFs adsorbent material are mainly concentrated between 10-20nm, and the relevant specific surface area and pore structure parameters are listed in Table 1. As can be seen from Table 1, the Langmuir specific surface area is 151.37m²Per g, pore volume of the micropores 0.87cm³G, adsorption volume 1.08cm³G, benzene gas molecules (molar volume 89.16 cm)³Mol), molecular weight of 78.11g/mol, so that the molecular volume of benzene gas is 1.141cm³(g) the adsorption cumulative volume of the Ce-MOFs adsorption material is 1.08cm³The concentration/g is identical, which is beneficial to the progress of the adsorption reaction.

TABLE 2 pore size distribution and specific surface area of Ce-MOFs adsorbent materials

FIG. 7 is a Scanning Electron Microscope (SEM) spectrum of the Ce-MOFs adsorbing material. As can be seen from the figure, the Ce-MOFs adsorbing material is formed by stacking a large number of irregular sheet-shaped or rod-shaped structures, and the surface of the Ce-MOFs adsorbing material has porous and pore structure morphology, so that the specific surface area and the porosity of the Ce-MOFs are greatly increased, and the adsorption of benzene gas molecules with corresponding pore sizes is facilitated.

FIG. 8 is a thermogravimetric plot (TGA) of the Ce-MOFs adsorbent material. The TGA profile of Ce-MOFs materials is not uniform, probably due to the structure of the resulting ligand GBE and the GBE reacting with the rare earth Ce metal when reacting both the natural biomass material methyl-alpha-D-galactopyranoside and the organic compound phthalic anhydride³⁺The solution coordination ratio is different, and the variety diversity of the obtained Ce-MOFs is caused. As can be seen from the figure, the whole-course weight loss of the Ce-MOFs is divided into three stages, and most of the residual mass after 610 ℃ is cerium nitrate oxide. Wherein the weight loss in the first stage is caused by evaporation of moisture or crystal water in the Ce-MOFs structure and solvent micromolecules in pore channels under the heated condition; the weight loss in the second stage is mainly caused by the decomposition of sugar rings and the decomposition of groups in a low-polarity chemical environment; the third stageWeight loss is a result of thermal decomposition of aromatic rings and groups in a highly polar chemical environment. From the above analysis, the overall thermal stability of the Ce-MOFs adsorbent material is not high throughout.

FIG. 9 is an XRD spectrum of the Ce-MOFs adsorbent material. As can be seen from FIG. 9, the main diffraction peak of the Ce-MOFs adsorption material appears at the position where 2 θ is less than 10 °, which indicates that the Ce-MOFs material has poor crystallinity and a large amount of amorphous substances exist in the structure.

From FTIR and EDS profiling analysis, organic ligands GBE and Ce³⁺Molecular rearrangement and coordination self-assembly reaction are carried out between the two groups; the specific surface area and the average pore diameter are analyzed, so that the Ce-MOFs adsorption material belongs to a mesoporous and microporous adsorption material and comprises partial microporous pores; the result of SEM atlas analysis can show that the surface of the Ce-MOFs adsorbing material is rough, and the Langmuir specific surface area is 151.37m²The pore diameter and pore volume size thereof, namely the pore volume of the micropores, are 0.87cm³(g) cumulative volume of adsorption of 1.08cm³G, benzene gas molecular molar volume 1.141cm³The volume/g is matched with the adsorption accumulation volume of the Ce-MOFs adsorption material, thereby being beneficial to the proceeding of the adsorption reaction. Preparing ligand GBE from methyl-alpha-D-galactopyranoside and phthalic anhydride as biologically friendly raw materials under neutral alkalescence condition, and reacting with Ce³⁺The Ce-MOFs adsorbing material obtained by the coordination self-assembly reaction has poor crystallinity and low whole-process thermal stability. By combining the characterization results, the Ce-MOFs adsorbing material successfully achieves the purpose and the requirement of the expected design of benzene gas adsorption.

Principle of adsorption experiment

A certain amount of Ce-MOFs adsorption material is accurately weighed and placed at a test position of an instrument (3H-2000P, a multi-station gravimetric steam adsorption instrument, Betsard instruments science and technology Limited, Beijing), the Ce-MOFs adsorption material is heated, vacuum degassing is carried out on the Ce-MOFs adsorption material, a sample chamber is in a vacuum environment, adsorbed benzene gas is evaporated to be steam from liquid in a reagent tube, after the adsorbed benzene gas is adsorbed by the Ce-MOFs material, the change of the weight of the Ce-MOFs sample before and after adsorption under a certain relative partial pressure is weighed by a microbalance, and the adsorption and desorption amount of the sample to specific gas is measured. The adsorbate is the same gas, at most four samples can be tested in parallel in one adsorption experiment, and the average value of the results is taken.

Adsorption of Ce-MOFs adsorption material to benzene

Influence of GBE preparation time on benzene adsorption amount

FIG. 10 is a graph showing the influence of Ce-MOFs on the amount of adsorbed benzene gas when GBE production time is different. As can be seen from FIG. 10, the relative partial pressures (P/P) during the adsorption process₀) 0.90, Ce³⁺The molar ratio of the synthesized GBE and the ligand GBE is 1:3, the molar ratio of the synthesized raw materials of the GBE, namely methyl-alpha-D-galactopyranoside and phthalic anhydride is 1:3, 1:4 and 1:5 respectively, shows that when the preparation time of the GBE is 8 hours, the adsorption capacity of the Ce-MOFs adsorption material to benzene is higher than that of 9 hours.

Effect of the feed molar ratio of the two feedstocks for GBE preparation on benzene adsorption

FIG. 11 is a graph showing the influence of the feed mole ratio of two ligand raw materials on the benzene adsorption amount at the GBE production time of 8 hours. As can be seen from FIG. 11, the relative partial pressures (P/P) during the adsorption process₀) 0.90, Ce³⁺When the molar ratio of the ligand to GBE is 1:3 and the GBE preparation time is 8h and the molar ratio of the synthetic raw materials of GBE, namely methyl-alpha-D-galactopyranoside and phthalic anhydride is 1:3, the adsorption effect of the obtained Ce-MOFs adsorption material on benzene gas is optimal.

Ce³⁺Influence of molar ratio to GBE on benzene adsorption amount

FIG. 12 is Ce at a GBE production time of 8h³⁺Influence curve of the adsorption amount of the benzene gas when the molar ratio is different from GBE. As can be seen from FIG. 12, the relative partial pressures (P/P) during the adsorption process₀) 0.90, GBE preparation time is 8h, and when the molar ratio of the GBE raw materials for synthesis of methyl-alpha-D-galactopyranoside to phthalic anhydride is 1:3, Ce is in³⁺The adsorption capacity of the prepared Ce-MOFs adsorption material to benzene gas is maximum 128.9870mg/g under the condition that the molar ratio of the prepared Ce-MOFs adsorption material to the ligand GBE is 1: 3.

Comparison of gas adsorption amounts of representative VOCs in wood drying by Ce-MOFs adsorption material

Adsorption of Ce-MOFs adsorption material to beta-pinene gas

FIG. 13 shows a Ce-MOFs adsorbentThe influence curve of the material on the beta-pinene adsorption capacity under the condition of different relative gas partial pressures. As can be seen from fig. 13, when the adsorption conditions are the optimum conditions: the preparation time of GBE is 8h, the molar ratio of the synthesized raw materials of GBE, namely methyl-alpha-D-galactopyranoside and phthalic anhydride is 1:3, and Ce is³⁺The molar ratio of the ligand GBE is 1:3, when the relative partial pressure (P/P) of the adsorption process is₀) When the adsorption quantity of the Ce-MOFs adsorption material to the beta-pinene is 0.90, the maximum adsorption quantity of the Ce-MOFs adsorption material to the beta-pinene is 116.5260 mg/g.

Adsorption of carbon tetrachloride by Ce-MOFs adsorption material

FIG. 14 is a graph showing the influence of Ce-MOFs adsorbing material on the carbon tetrachloride adsorption amount under different relative gas partial pressures. As can be seen from fig. 14, when the adsorption conditions are the optimum conditions: the preparation time of GBE is 8h, the molar ratio of the synthesized raw materials of GBE, namely methyl-alpha-D-galactopyranoside and phthalic anhydride is 1:3, and Ce is³⁺The molar ratio of the ligand GBE is 1:3, when the relative partial pressure (P/P) of the adsorption process is₀) When the adsorption amount is 0.90, the adsorption amount of the Ce-MOFs adsorption material to carbon tetrachloride is 104.1860mg/g at the maximum value.

Adsorption of Ce-MOFs adsorption material on alpha-pinene

FIG. 15 is a curve showing the influence of the Ce-MOFs adsorbent material on the alpha-pinene adsorption amount under different relative gas partial pressures. As can be seen from fig. 15, when the adsorption conditions are the optimum conditions: the preparation time of GBE is 8h, the molar ratio of the synthesized raw materials of GBE, namely methyl-alpha-D-galactopyranoside and phthalic anhydride is 1:3, and Ce is³⁺The molar ratio of the ligand GBE is 1:3, when the relative partial pressure (P/P) of the adsorption process is₀) When the adsorption quantity of the Ce-MOFs adsorption material to alpha-pinene is 0.90, the maximum adsorption quantity of the Ce-MOFs adsorption material to the alpha-pinene is 57.6780 mg/g.

In summary, under the optimal preparation conditions: relative partial pressure of gas (P/P)₀) 0.90, the preparation time of the ligand GBE is 8h, the feeding molar ratio of two ligand raw materials (methyl-alpha-D-galactopyranoside and phthalic anhydride) is 1:3, and the central rare earth ion Ce³⁺When the molar ratio of the Ce-MOFs adsorbing material to the ligand GBE is 1:3, the comparison of the adsorption quantity data of the prepared Ce-MOFs adsorbing material to specific VOCs (benzene, beta-pinene, carbon tetrachloride and alpha-pinene) released in the high/normal temperature drying process of the wood shows that Ce-The adsorption amount of the MOFs adsorption material to the benzene gas is the maximum value. Therefore, the Ce-MOFs adsorbing material is a targeted adsorbing material for benzene gas. The analysis of the experimental data can lay a certain theoretical basis for the treatment of VOCs gaseous pollutants released in the wood drying industry in China.

Comparative data of adsorption capacities of different materials to benzene gas

Table 3 compares the maximum adsorption data for benzene for several different adsorbents.

TABLE 3 comparison of adsorption capacities for benzene for different adsorbents

Adsorbent and process for producing the same	Maximum adsorption of benzene (mg/g)
		Ce-MOFs adsorption material	128.9870
La-MOFs	2.7930
		Nd-MOFs	102.2270
Nano lignocellulose/montmorillonite composite adsorption material	0.9420
		Monolithic porous carbon	117
Acid activated palygorskite	9.72
		FeSO₄-ACF₂	35.00
Al₂O₃	19.7

It can be known from the comparison values of the maximum adsorption amounts of benzene in the four different adsorption materials in table 3 that the adsorption capacity of the novel Ce-MOFs adsorption material designed in the application to benzene vapor of one of specific VOCs gases released in the wood high/normal temperature drying process is obviously stronger than that of the other adsorption materials. Therefore, the Ce-MOFs adsorbing material provided by the invention has wide application prospect in the field of treatment of benzene gas released in the high/normal temperature drying process of industrial wood.

Desorption experiments

The desorption process is exactly opposite to the adsorption process, and the desorption process is the relative partial pressure (P/P) of gas in the process of carrying out the adsorption experiment₀) Gradually decrease from the optimum value of 0.90 to the point where the relative partial pressure is 0 (specific operation: partial benzene gas in the instrument is pumped out by utilizing a vacuum pump so as to reduce partial pressure, the adsorption quantity is also reduced, and the desorption quantity is correspondingly increased. ) And measuring the adsorption quantity at the moment by a weighing method, namely the desorption quantity of the Ce-MOFs material to the gas.

The experimental result shows that the adsorption quantity of the Ce-MOFs adsorption material to the benzene gas is gradually increased along with the increase of the relative partial pressure of the gas in the adsorption experimental process; the optimal preparation process parameters of the Ce-MOFs adsorption material are as follows: relative partial pressure (P/P)₀) 0.90, the preparation time of the ligand GBE is 8h, the feeding molar ratio of two ligand raw materials (methyl-alpha-D-galactopyranoside and phthalic anhydride) is 1:3, and the central rare earth ion Ce³⁺The molar ratio to the ligand GBE is 1: 3. The adsorption capacity of the novel Ce-MOFs adsorption material prepared under the optimal conditions on the specific benzene gas released in the high/normal temperature drying process of the wood reaches the maximum value of 128.9870 mg/g.

The present invention is not limited to the above-described examples, and various changes can be made without departing from the spirit and scope of the present invention within the knowledge of those skilled in the art.

Claims

1. The Ce-MOFs material for adsorbing VOCs released in the wood drying process is characterized by being obtained by carrying out molecular rearrangement and self-assembly on serrated methyl-alpha-D-galactopyranoside aromatic acid ester with coordination capacity and a cerium nitrate solution, wherein the methyl-alpha-D-galactopyranoside aromatic acid ester is synthesized by methyl-alpha-D-galactopyranoside and phthalic anhydride under the catalytic action of N, N-diisopropylethylamine.

2. The Ce-MOFs material according to claim 1, wherein the Ce is selected from the group consisting of Ce, Ce-MOFs, for the adsorption of VOCs released during the drying of wood, and Ce-MOFs, for the adsorption, Ce-MOFs, and/V, Ce-MOFs, for the adsorption of the adsorption, Ce-MOFs, wherein the adsorption is selected from the release VOCs released during the drying of the wood³⁺The molar ratio of the aromatic acid ester of the serrated methyl-alpha-D-galactopyranoside ranges from 1: 1-1: 5.

3. the Ce-MOFs material for the adsorption of VOCs released by wood drying process according to claim 1, wherein the molar ratio of methyl- α -D-galactopyranoside and phthalic anhydride in DIEA is in the range of 1: 1-5.

4. The Ce-MOFs material according to claim 3, wherein said jagged methyl- α -D-galactopyranoside arylate with coordination capacity is synthesized by methyl- α -D-galactopyranoside and phthalic anhydride under DIEA catalysis for 8-9 hours.

5. The Ce-MOFs material according to claim 1, wherein the Ce is selected from the group consisting of Ce, Ce-MOFs, for the adsorption of VOCs released during the drying of wood, and Ce-MOFs, for the adsorption, Ce-MOFs, and/V, Ce-MOFs, for the adsorption of the adsorption, Ce-MOFs, wherein the adsorption is selected from the release VOCs released during the drying of the wood³⁺The molar ratio of the aromatic acid ester to the serrated methyl-alpha-D-galactopyranoside is 1: 3.

6. the Ce-MOFs material according to claim 5, wherein the molar ratio of methyl- α -D-galactopyranoside to phthalic anhydride in DIEA solvent is 1: 3.

7. the Ce-MOFs material for the adsorption of VOCs released during the drying of wood according to claim 6, wherein said jagged methyl- α -D-galactopyranoside aromatic acid ester with coordinating ability is synthesized by methyl- α -D-galactopyranoside and phthalic anhydride under the catalytic action of DIEA over 8 hours.

8. The use of Ce-MOFs material for the adsorption of VOCs released during the drying of wood according to claim 1, wherein the relative gas partial pressure during adsorption is controlled in the range of 0.60 to 0.95.

9. The use of Ce-MOFs material for the adsorption of VOCs released during the drying of wood according to claim 1, wherein the relative gas partial pressure during adsorption is controlled to 0.90.