AU2020104343A4 - SPECIAL RARE EARTH METAL La-MOFs ADSORPTION MATERIAL FOR α-PINENE TARGETED INTELLIGENT ADSORPTION AND PREPARATION METHOD THEREOF - Google Patents

Abstract

The invention discloses a special rare earth metal La-MOFs adsorption material for a-pinene targeted intelligent adsorption and a preparation method thereof. In the invention, the rare earth metal La" is used as the ion center, and methyl-a-D-galactopyranoside and phthalic anhydride are used as the two ligand raw materials; under the catalysis of triethylamine, a coordinating dentate methyl-a-D-galactopyranoside aromatic acid ester (GE) is synthesized as an organic ligand for the construction of MOFs intelligent adsorption materials; and the GE and rare earth metal lanthanum nitrate solution are subjected to molecular rearrangement and coordination self-assembly to synthesize a series of new La-MOFs intelligent a-pinene adsorption materials. Analyze the structure of La-MOFs through FTIR, SEM/EDS, BET, TGA and other characterization methods, and the result shows that the structure of the La-MOFs intelligent adsorption material fully meets the design requirements for the intelligent adsorption of a-pinene gas, and has an excellent adsorption effect on the a-pinene gas, which is one of the specific VOCs released during domestic Pinus sylvestris high temperature/normal temperature drying process. 1 DRAWINGS b 1 45 .. .1287 1705 31440 580 3420 3077 157 1486 1548 145 1487 1278 1702 4000 3500 300 2500 2000 1500 100 Wave Number/cm! FIG. 4 c eV ta~ 2 4 6 8 10 12 14 16 18 20 keY FIG. 5 2

Description

DRAWINGS

b 1 45 .. .1287

1705 31440

580 3420 3077 157 1486

1548 145 1487 1278 1702 4000 3500 300 2500 2000 1500 100 Wave Number/cm!

FIG. 4

c eV

ta~

2 4 6 8 10 12 14 16 18 20 keY

FIG. 5

DESCRIPTION

SPECIAL RARE EARTH METAL La-MOFs ADSORPTION

MATERIAL FOR a-PINENE TARGETED INTELLIGENT

ADSORPTION AND PREPARATION METHOD THEREOF FIELD OF THE INVENTION

[0001] The invention belongs to the technical field of functional materials.

BACKGROUND OF THE RELATED ART

[0002] Volatile organic compounds (VOCs) refer to volatile organic compounds with a

boiling point lower than 260°C and a saturated vapor pressure higher than 133.322 Pa at

room temperature and pressure. Many countries have their focus on the definition of VOCs,

which are roughly divided into two categories: the first category is the US ASTMD3960-98

standard and the US Federal Environmental Protection Agency (EPA) defines whether to

participate in atmospheric photochemical reactions. The second category is the World Health

Organization (WHO, 1989), the international standard of general terms for paints and

varnishes, the German DIN 55649-2000 standard and the German DIN 55649-2000 standard

which define volatility. At present, industrialized VOCs pollution has become a major source

of air pollutants.

[0003] VOCs mainly contain organic gaseous pollutants such as oxygen/nitrogen/sulfur

organics, pinenes, aromatic hydrocarbons and halogenated hydrocarbons, which have the

characteristics of strong volatility, irritation, and toxic and harmful properties, and have

become one of the main causes of human cancer. The harm of VOCs to the human body

mainly includes the following aspects: 1. under sunlight, nitrogen oxides NOx can easily react

with VOCs in the atmosphere to generate ozone, peroxyacetyl nitrate (PAN), aldehydes and

other photochemical smog, which causes secondary pollution, stimulates human eyes and

respiratory system, endangers human health, endangers the growth of crops, and causes the

death of crops; 2. most VOCs are toxic and foul-smelling, making people easy to contract

cumulative respiratory diseases, which may cause acute poisoning and even death under the

sudden action of high concentrations; 3. VOCs are flammable and explosive, and easily cause

DESCRIPTION explosion when discharged in high concentration; 4. some VOCs can destroy the ozone layer.

Therefore, the effective prevention and control of VOCs has attracted widespread attention

from the government and the public.

[0004] Specific VOCs gas pollutants can be released during the wood high/normal

temperature drying process, including terpenoids, mainly monoterpenes, such as a-pinene,

myrcene, camphene, p-pinene, etc., and non-terpene substances, such as carbon tetrachloride,

aromatic hydrocarbons, carboxylic acids and other organic substances, accompanied by toxic

and harmful substances such as formaldehyde and acetaldehyde. Among the specific VOCs

gases released during the wood high/normal temperature drying process, some of the gas

components are inherent to wood, and some are produced through certain chemical reactions;

for example, a-pinene is one of the main terpenes released during domestic Pinus sylvestris

high/normal temperature drying process, and it is easily oxidized to form aldehydes, ketones,

acids and other compounds with a ring structure.

[0005] a-Pinene is a colorless and transparent liquid under normal temperature and pressure,

which has the odor of turpentine, toxic, slightly soluble in water, insoluble in propylene

glycol, glycerin, and soluble in most organic solvents such as ethanol, ether, chloroform, and

glacial acetic acid; the molecular formula thereof is C1 0 H 16 , the molecular weight is 136.234

g/mol, the density is 0.86 g/cm3 (20 °C ), the boiling point is 156.0 °C , the saturated vapor

pressure is 0.63 kPa (27°C), and the vapor density is 4.7 g/L. a-Pinene can form an explosive

mixture with air, which will cause combustion and explosion when exposed to open flames

and high thermal energy, and will react strongly with oxidants and produce carbon dioxide

and toxic carbon monoxide gas after combustion. The human body's susceptibility to

a-pinene toxicity varies greatly. Inhalation, ingestion, or absorption through the skin is

harmful to the body. High-concentration a-pinene vapor has a strong irritating effect on the

eyes, respiratory tract mucosa, and skin, which can quickly show burning sensation, shortness

of breath, headache, confusion, vomiting, coma, anesthesia, acute liver necrosis and renal

failure in severe cases, and a few may have myocardial damage.

[0006] At present, the processing technology of VOCs is roughly divided into two types:

recovery technology and destruction technology. The recovery technology includes:

condensation recovery method, membrane separation method, adsorption method and

DESCRIPTION solution absorption method; the destruction technology includes catalytic combustion method, thermal combustion method, plasma method and biodegradation. These technologies have achieved good adsorption effects in the treatment of industrial VOCs, but each has certain limitations. For example, the condensation recovery method is suitable for the treatment of atmospheric and medium-concentration VOCs, which has a high cost of use and can also be used to recover useful components; however, the absorbent is difficult to select, the range of absorption is limited, and the absorbed liquid needs to be further processed, otherwise it may cause secondary environmental pollution. The combustion method has the advantages of high efficiency, thorough treatment, elimination of malodors, and low pollution; however, because the final products of combustion and oxidation of VOCs are C0 2, H 20, etc., useful substances cannot be recovered by this method, and the cost of catalysts used in catalytic combustion is high, which leads to high costs. The plasma technology has the characteristics of simple process, low energy consumption, short process, and good operability, especially in terms of energy saving, and has a wide range of applications; however, due to its complex reaction process, it is susceptible to many external factors, and the discharge process will produce polymerization reaction to generate polymer, accompanied by a small amount of incomplete combustion product CO, etc., so further research and improvement are needed. The photocatalytic degradation technology is mainly suitable for the treatment of VOCs with low concentration (less than 1000 ppm) and small gas volume; its advantages are rapid and efficient reaction process, low energy consumption and no secondary pollution; however, there are some disadvantages; for example, the photocatalytic reaction quantum yield is relatively low, the catalyst has strict requirements on the characteristic wavelength of the excitation source, and when the pollutant concentration is high, a large catalytic area is required, which makes it uneconomical compared with other methods. The adsorption method has mature technology, simple operation, low energy consumption, high purification efficiency and high recovery rate, which is a VOCs treatment technology that is currently applied and promoted. The most important thing in the adsorption method is to select the adsorption material. Currently, the adsorption materials reported in the literature generally include activated carbon and its modified materials, molecular sieves, montmorillonite-based mesoporous materials and MOFs; however, because the preparation process of activated

DESCRIPTION carbon and its modified materials is relatively cumbersome, and various preparation processes such as high-temperature drying and carbonization are required; moreover, its adsorption performance is greatly affected by the carbonization time; prolonged burning under high temperature conditions will easily cause graphitization of the amorphous fixed carbon, resulting in difficulty in activation; in addition, high temperature will destroy the internal pore structure, surface active sites and surface chemical properties of activated carbon materials, which reduces the adsorption quantity, thus limiting its promotion and application in the treatment of industrial VOCs gas pollution. The preparation process of molecular sieves has problems such as high price, energy loss and secondary environmental pollution, and cannot be used for adsorption under strong inorganic acid and strong alkali conditions, which makes it difficult to effectively remove part of the VOCs released by wood drying, and results in limited application. In the preparation process of montmorillonite-based mesoporous materials, the acidity (pH value) of the solution needs to be strictly controlled, and the pH value will be affected by many factors; if the optimal acidity value of the system cannot be adjusted accurately, the adsorption performance of montmorillonite-based materials will easily decrease, which is not conducive to the effective removal of VOCs; therefore, there are certain limitations in the adsorption application field of VOCs released by wood drying.

[0007] Metal organic framework materials (MOFs) are a new type of porous framework materials, which are crystalline materials with a periodic three-dimensional network framework formed by the self-assembly process of organic ligands and metal ions. As a new type of functional molecular material, MOFs material has the advantages of huge specific surface area, adjustable pore size, ordered micropore structure, diverse pore size and skeleton structure, modifiable pore surface functional groups, and unsaturated metal coordination points compared with other adsorption materials, which has attracted much attention in the field of VOCs gas adsorption research and has shown great application potential. Since Professor Yaghi first synthesized MOF-5 hydrogen storage material in 1995, its catalytic performance, fluorescence characteristics and adsorption properties have attracted the attention of scientific researchers, and have gradually been used in various fields of social life and industrial production. With the continuous exploration of scientific research and analysis

DESCRIPTION from the perspective of different metal ions, the synthesis of MOFs has experienced the

selective construction of central metal ions from transition metal ions, rare earth metal ions to

d-f mixed metal ions, light metals, etc. Among them, the number of reported structures of

MOFs adsorbing materials containing rare earth metal ions is much smaller than that of

transition metal ions. In the existing literature, most of the ligands are nitrogen-containing

and oxygen-containing heterocyclic compounds; this type of MOFs materials synthesized

with metal ions by conventional single-containing O/N heterocyclic organic compounds as

ligands have disordered atomic arrangement in their pore size, porosity and open space; in

addition, the density and regularity are low, which leads to a small adsorption force on the

organic gaseous pollutants terpene molecules in the exhaust gas of wood drying industry.

[0008] The application uses organic biological materials that are good for the human

environment - sugars and glycosides and organic benzo-containing 0 rings as ligands;

however, there are few reports on the three-dimensional porous network framework material

MOFs constructed by molecular rearrangement and self-assembly with rare earth metal ions

La3 +.

SUMMARY OF THE INVENTION

[0009] The purpose of the invention is to overcome the above shortcomings in the prior art,

and provide a special rare earth metal La-MOFs adsorption material for a-pinene targeted

intelligent adsorption and a preparation method thereof.

[0010] The invention first studied the types and contents of specific VOCs released by

domestic Pinus sylvestris during high temperature/normal temperature drying process, and

the result shows that the VOCs released by pine wood during the drying process include

aldehydes, terpenes, aromatics, alkanes, halogenated hydrocarbons, etc. Therefore, the

a-pinene gas with the highest content and the most representative terpenes is selected as the

main research object. According to the molecular structure and chemical properties of

a-pinene gas, a new type of intelligent targeted intelligent adsorption material for rare earth

metal La-MOFs is designed.

[0011] In the experiment, the rare earth metal La 3* is used as the ion center, and

methyl-a-D-galactopyranoside and phthalic anhydride are used as the two ligand raw

DESCRIPTION materials; under the catalysis of triethylamine, a coordinating dentate

methyl-a-D-galactopyranoside aromatic acid ester (GE) is synthesized as an organic ligand

for the construction of MOFs intelligent adsorption materials; and the GE and rare earth

metal lanthanum nitrate solution are subjected to molecular rearrangement and coordination

self-assembly to synthesize a series of new La-MOFs intelligent a-pinene adsorption

materials. Analyze the structure of La-MOFs through FTIR, SEM/EDS, BET, TGA and other

characterization methods, and the result shows that the structure of the La-MOFs intelligent

adsorption material fully meets the design requirements for the intelligent adsorption of

a-pinene gas, and has an excellent adsorption effect on the a-pinene gas, which is one of the

specific VOCs released during domestic Pinus sylvestris high temperature/normal

temperature drying process.

[0012] Technical Solution of the Invention

[0013] A preparation method of a special rare earth metal La-MOFs adsorption material for

a-pinene targeted intelligent adsorption, comprising the following steps:

[0014] first, synthesis of methyl-a-D-galactopyranoside aromatic acid ester (GE): pouring

phthalic anhydride into a container, adding acetone, magnetically stirring, then adding

methyl-a-D-galactopyranoside, heating up to 62-70°C; the mixture is refluxed under stirring

and heating; cooling the obtained liquid to room temperature, adding P 2 0 5 to dry and filter,

and evaporating the obtained filtrate to remove the solvent acetone to obtain a colorless

viscous liquid GE;

[0015] the adding amount ratio of phthalic anhydride and methyl-a-D-galactopyranoside is

1:1-5:1; the adding amount of the catalyst triethylamine is 5-15 mL.

[0016] Second, synthesis of the La-MOFs intelligent adsorption material: using the solvent

synthesis method; placing the ligand GE obtained in the previous step in a container, and

adding acetone to fully dissolve it to obtain a GE solution; dissolving lanthanum nitrate in

distilled water to obtain a lanthanum nitrate solution; adding the GE solution and the

lanthanum nitrate solution into the container in a volume ratio of 1:1-5:1, mixing uniformly,

and magnetically stirring, then adding triethylamine dropwise to adjust the pH of the solution

to 7.0-8.0, stirring at room temperature, and filtering the lanthanum nitrate/GE mixture in

vacuum; the obtained solid is the La-MOFs intelligent adsorption material.

DESCRIPTION

[0017] The obtained La-MOFs intelligent adsorption material is washed with deionized water

(2-5 times) and acetone (3-5 times), and dried under vacuum at 60°C to a constant weight.

[0018] The invention further provides a special rare earth metal La-MOFs adsorption

material for a-pinene targeted intelligent adsorption prepared by the method above.

[0019] Advantages and beneficial effects of the invention:

[0020] 1. In recent years, my country's timber drying industry has concentrated on timber

production and import bases. Manzhouli, Erenhot in Inner Mongolia and Suifenhe in

Heilongjiang are the main port cities where my country imports timber from Russia. In 2017,

the import volume exceeded 30 million cubic meters, and 70% of the imported wood needs to

be dried at the port. VOCs emitted during the wood drying process have become the focus of

the reporting department.

[0021] 2. Inner Mongolia Autonomous Region is the hometown of rare earths, and the rare

earth metal lanthanum selected in the invention reflects regional advantages; one of the

selected ligands is methyl-a-D-galactopyranoside, belonging to polyhydroxy acetal

glycosides and has the properties of non-ionic surfactants, which is an environmentally

friendly biomass raw material with a wide range of sources, and its industrial application has

been favored and valued. In addition, the selected raw materials have a wide range of sources,

with non-toxic and harmless, and low recycling costs. The La-MOFs intelligent adsorption

material obtained by molecular rearrangement and self-assembly has many advantages such

as simple operation, stable structure, no secondary environmental pollution, and multiple

recycling.

[0022] 3. The invention uses phthalic anhydride and methyl-a-D-galactopyranoside to

prepare organic ligand GE containing ester carbonyl sugar ring, wherein phthalic anhydride

contains a benzene ring, and methyl-a-D-galactopyranoside is a unique cyclic tetrahydroxy

polyol and acetal structure. The hydroxyl group on the ring is very easy to react with

carboxylic acid or acid anhydride, and the combination of the two increases the length of the

ligand and the three-dimensional framework. In addition, the lone pair of electrons in the

carbonyl group of the GE ester is easy to combine with the empty d orbitals of the rare earth

metal ions through coordination bonds and electrostatic attraction and other interaction forces

to form a hinged hole-shaped skeleton structure. This special topological structure has a

DESCRIPTION larger pore skeleton, which is in line with the volume size of a-pinene (molar volume: 154.9

cm/mol) gas. Moreover, because a-pinene is a bridged ring compound, the structure contains

a six-membered ring, the main unit is cyclohexene, and there is a carbon-carbon double bond

in the structure. The n bond is formed by two carbon atoms with sp2 hybrid orbital, and there

are n electrons that are easy to flow. When adsorbing with La-MOFs intelligent adsorption

material with empty orbitals, n electrons can also be filled into the empty 4f, 5d, and 6s

orbitals of La+([Xe]4f°5d6s), and a certain coordinate bonding occurs, which enables

La-MOFs to have excellent adsorption performance for a-pinene gas.

[0023] 4. For the first time, the invention designs a new type of intelligent a-pinene gas

adsorption material for the molecular structure and corresponding physical and chemical

properties of a-pinene, which is one of the specific VOCs gases released during wood drying,

and obtains an excellent adsorption effect. In addition, the La-MOFs intelligent adsorption

material can be reused for many times after desorption experiment, and its adsorption

quantity is not significantly reduced after multiple use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a molecular structure diagram of a-pinene, wherein a is a three-dimensional

diagram of a-pinene molecule, and b is a plan view of a-pinene molecule.

[0025] FIG. 2 is a connection model of La" and the ligand GE and a molecular simulation

diagram of La-MOFs, wherein a is a simulation diagram of

methyl-a-D-galactopyranoside:phthalic anhydride=1:1, b is

methyl-a-D-galactopyranoside:phthalic anhydride=1:2, c is

methyl-a-D-galactopyranoside:phthalic anhydride=1:3, and d is a simulation diagram of the

structure of the La-MOFs intelligent adsorption material.

[0026] FIG. 3 is a flow chart of the La-MOFs intelligent adsorption material preparation and

adsorption characterization experiment.

[0027] FIG. 4 is an infrared spectrum of the ligand GE and La-MOFs- intelligent adsorption

material, wherein curve a represents the ligand GE and b represents the La-MOFs-1

intelligent adsorption material.

[0028] FIG. 5 is an EDS diagram of the La-MOFs-1 intelligent adsorption material.

DESCRIPTION

[0029] FIG. 6 is a nitrogen adsorption-desorption curve of the La-MOFs-1 intelligent

adsorption material.

[0030] FIG. 7 is a pore size distribution curve of the La-MOFs-1 intelligent adsorption

material.

[0031] FIG. 8 is an SEM image of the La-MOFs-1 intelligent adsorption material.

[0032] FIG. 9 is a TGA diagram of the La-MOFs-1 intelligent adsorption material.

[0033] FIG. 10 is a diagram showing the influence of GE preparation time on the adsorption

quantity of a-pinene, wherein curve a represents La-MOFs-4, b represents La-MOFs-5, and c

represents La-MOFs-1.

[0034] FIG. 11 is a diagram showing the influence of the feeding ratio of the two raw

materials on the adsorption quantity of a-pinene.

[0035] FIG. 12 is a diagram showing the influence of the molar ratio of Ce 3 to GE on the

adsorption quantity of a-pinene.

[0036] FIG. 13 is a diagram showing the influence of the La-MOFs-1 intelligent adsorption

material on the adsorption quantity of p-pinene.

[0037] FIG. 14 is a diagram showing the influence of the La-MOFs-1 intelligent adsorption

material on the adsorption quantity of carbon tetrachloride.

[0038] FIG. 15 is a diagram showing the influence of the La-MOFs-1 intelligent adsorption

material on the adsorption quantity of benzene.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Design of the La-MOFs Intelligent Adsorption Material

[0040] The structure design of the La-MOFs adsorption material: taking the molecular

structure (FIG. 1 is a molecular structure diagram of a-pinene, wherein FIG. la is a

three-dimensional diagram of a-pinene molecule, and FIG. lb is a plan view of a-pinene

molecule) of a-pinene gas and its physical and chemical properties as the research content, to

design and synthesize a special intelligent adsorption material for La-MOFs for treating

a-pinene gas. The adsorption material is composed of metal La" and GE through

coordination or chelation force, electrostatic attraction, etc., and molecules rearrange and

self-assemble to synthesize La-MOFs intelligent adsorption material. Its structure contains

DESCRIPTION benzene ring, polyhydroxy hexatomic ring and other structures, and it has coordinate bonding

and electrostatic force interaction with the empty orbital 4f, 5d and 6s of rare earth metal

La3 +([Xe]4f'5d6s') {La[Xe]4f5d 6s 1 2 }. The structure of the new La-MOFs intelligent

adsorption material has a typical topological structure rich in a large number of mesopores

and porosity, which is most conducive to the adsorption of a-pinene gas with a molar volume

of 154.9 cm3 /mol, and the adsorption quantity is significant. The application uses Chemoffice

Professional16.0Suite software to establish a structural simulation diagram with GE as an

organic ligand, that is, the two molecules of methyl-a-D-galactopyranoside and phthalic

anhydride are connected in a molar ratio of 1:1 (FIG. 2a), 1:2 (FIG. 2b), and 1:3 (FIG. 2c),

respectively, and FIG. 2d is a molecular simulation structure diagram of the La-MOFs

intelligent adsorption material.

[0041] Experimental Route and Process

[0042] The preparation scheme of the La-MOFs intelligent adsorption material, the route and

experimental flow chart of adsorption/desorption experiment and material characterization

analysis experiment are shown in FIG. 3.

[0043] 1. Preparation of a special rare earth metal La-MOFs adsorption material for a-pinene

targeted intelligent adsorption.

[0044] Embodiment 1

[0045] 1. Synthesis of the ligand GE: weighing 19.08 g of phthalic anhydride and pouring it

into a flat-bottomed flask, adding 50 mL of acetone, magnetically stirring, and stirring at

°C to fully dissolve it, then adding 5 g of methyl-a-D-galactopyranoside, heating up to

66 °C , adding 5 mL of catalyst triethylamine, and the mixture is refluxed for 9 hours with

stirring and heating, and cooling the obtained liquid to room temperature; adding an

appropriate amount of P 2 0 5 to dry and filter, and evaporating the obtained filtrate to remove

the solvent acetone at 60°C to obtain a colorless viscous liquid (GE). The obtained product is

tested by thin layer chromatography, and the developing solvents are ethyl acetate and

cyclohexane (Vethylacetate:Vcyclohexane=1:9), which proves that the product does not contain

unreacted phthalic anhydride.

[0046] 2. Synthesis of the La-MOFs intelligent adsorption material: using the solvent

synthesis method; accurately weighing 25.36 g of the ligand GE into an Erlenmeyer flask,

DESCRIPTION adding 20 mL of acetone to fully dissolve it; weighing 2.11 g of lanthanum nitrate and

dissolving it in 10 mL of distilled water. Measuring 10 mL of GE solution and 10 mL of

lanthanum nitrate solution and adding them to the Erlenmeyer flask, mixing uniformly and

magnetically stirring; adding 10 mL of triethylamine dropwise to adjust the pH of the

solution to about 8.0, stirring at room temperature for 4 hours, and filtering the lanthanum

nitrate/GE mixture in vacuum; the obtained solid is the La-MOFs-1 intelligent adsorption

material. Washing with deionized water and acetone for several times, and drying at 60°C in

vacuum to a constant weight.

[0047] Embodiment 2

[0048] The specific steps are the same as in Embodiment 1, wherein the adding amount of

"phthalic anhydride" in step 1 is changed to 3.81 g. (La-MOFs-2)

[0049] Embodiment 3

[0050] The specific steps are the same as in Embodiment 1, wherein the adding amount of

"phthalic anhydride" in step 1 is changed to 7.74 g. (La-MOFs-3)

[0051] Embodiment 4

[0052] The specific steps are the same as in Embodiment 1, wherein the adding amount of

"phthalic anhydride" in step 1 is changed to 11.45 g. (La-MOFs-4)

[0053] Embodiment 5

[0054] The specific steps are the same as in Embodiment 1, wherein the adding amount of

"phthalic anhydride" in step 1 is changed to 15.33 g. (La-MOFs-5)

[0055] Embodiment 6

[0056] The specific steps are the same as in Embodiment 1, wherein the acetone dissolution

temperature in step 1 is changed to 40°C. (La-MOFs-6)

[0057] Embodiment 7

[0058] The specific steps are the same as in Embodiment 1, wherein the acetone dissolution

temperature in step 1 is changed to 50°C. (La-MOFs-7)

[0059] Embodiment 8

[0060] The specific steps are the same as in Embodiment 1, wherein in step 1, after adding

methyl-a-D-galactopyranoside, the temperature is increased to 62C. (La-MOFs-8)

[0061] Embodiment 9

DESCRIPTION

[0062] The specific steps are the same as in Embodiment 1, wherein in step 1, after adding

methyl-a-D-galactopyranoside, the temperature is increased to 70°C. (La-MOFs-9)

[0063] Embodiment 10

[0064] The specific steps are the same as in Embodiment 1, wherein the reflux time after

heating in step 1 is changed to 8 hours. (La-MOFs-10)

[0065] Embodiment 11

[0066] The specific steps are the same as in Embodiment 1, wherein the reflux time after

heating in step 1 is changed to 10 hours. (La-MOFs-11)

[0067] Embodiment 12

[0068] The specific steps are the same as in Embodiment 1, wherein the mass of the ligand

GE in step 2 is changed to 6.25 g. (La-MOFs-12)

[0069] Embodiment 13

[0070] The specific steps are the same as in Embodiment 1, wherein the mass of the ligand

GE in step 2 is changed to 16.81 g. (La-MOFs-13)

[0071] Embodiment 14

[0072] The specific steps are the same as in Embodiment 1, wherein the mass of the ligand

GE in step 2 is changed to 37.04 g. (La-MOFs-14)

[0073] Embodiment 15

[0074] The specific steps are the same as in Embodiment 1, wherein the mass of the ligand

GE in step 2 is changed to 43.23 g. (La-MOFs-12)

[0075] Embodiment 16

[0076] The specific steps are the same as in Embodiment 1, wherein the volume of

triethylamine added in step 2 is changed to 5 mL. (La-MOFs-16)

[0077] Embodiment 17

[0078] The specific steps are the same as in Embodiment 1, wherein the volume of

triethylamine added in step 2 is changed to 15 mL. (La-MOFs-17)

[0079] Embodiment 18

[0080] The specific steps are the same as in Embodiment 1, wherein the stirring time after

adding triethylamine in step 2 is changed to 3.0 hours. (La-MOFs-18)

[0081] Embodiment 19

DESCRIPTION

[0082] The specific steps are the same as in Embodiment 1, wherein the stirring time after

adding triethylamine in step 2 is changed to 5.5 hours. (La-MOFs-19)

[0083] 2. Structure Characterization of the La-MOFs Intelligent Adsorption Material

[0084] Embodiment 20: FTIR Analysis

[0085] FIG. 4 is an infrared spectrum of the ligand GE (curve a in FIG. 4) and La-MOFs-1

intelligent adsorption material (curve b in FIG. 4). It can be seen from curve a in FIG. 4 that

the broad and strong peak of GE at 3360 cm-1 place is attributed to the incompletely reacted

hydroxyl group or free hydroxyl peak and hydrogen bond on the

methyl-a-D-galactopyranoside molecule; the 2976 cm-1 place is the C-H absorption peak of

methyl -CH 3 or -CH 2 on the aromatic ring of phthalic anhydride; the 1705 cm-1 place is the

characteristic absorption peak of carbonyl; the 1580 cm-1, 1545 cm-1, 1486 cm-1 and 1445

cm-1 places all correspond to the characteristic absorption peaks of benzene ring; the 1287

cm-1 place is the flexural vibration absorption peak of C-O in the carboxyl structure; the

double shoulder peaks at 1000 cm-1 and 1100 cm-1 places are the characteristic absorption

peaks of sugar rings. Compared with the infrared spectrum of the ligand GE, the absorption

peak of the La-MOFs intelligent adsorption material (curve b in FIG. 4) at 1705 cm-1 place is

almost completely suppressed, which indicates that the carbonyl group participates in the

reaction during molecular rearrangement and self-assembly site, and the rare earth metal La

successfully coordinated with the organic ligand GE.

[0086] Embodiment 21: EDS Analysis

[0087] FIG. 5 is an EDS diagram of the La-MOFs-1 intelligent adsorption material. It can be

seen from FIG. 5 that the La-MOFs intelligent adsorption material mainly contains six

elements: C, 0, N, La and Zr, wherein N, 0 and La are elements contained in metal

compounds, which can further prove that self-assembled assembly site reactions occurred

between -C=0 and La3 +; C and0 are elements contained in methyl-a-D-galactopyranoside

and phthalic anhydride, and Zr is an impurity in the process of sample testing and sample

preparation.

[0088] Embodiment 22: N 2 Adsorption-Desorption Results Analysis

[0089] FIG. 6 is an N2 adsorption-desorption curve of the La-MOFs-1 intelligent adsorption

material, and FIG. 7 is a pore size distribution curve of the La-MOFs-1 intelligent adsorption

DESCRIPTION material; Table 1 shows the specific surface area and related parameters of the La-MOFs-1

intelligent adsorption material. It can be seen from FIG. 6a that the N 2 adsorption-desorption

isothermal curve has a relatively obvious hysteresis loop, which indicates that there are a

large number of mesoporous and microporous structures in the La-MOFs-1 intelligent

adsorption material, and the curve conforms to the composite IV isotherm of the

adsorption-desorption isotherm curve, which is conducive to the adsorption of gas. When the

relative pressure (P/Po) reaches 0.60, the capillary aggregation of the adsorbate occurs in the

mesopores, and the adsorption quantity rises sharply. The gas in the low partial pressure

region also has a partial adsorption effect, which indicates that there is a strong adsorption

effect between the La-MOFs-1 intelligent adsorption material and N 2 . FIG. 7 is a pore size

distribution curve of the La-MOFs-1 intelligent adsorption material. It can be seen that the

pores of the La-MOFs-1 intelligent adsorption material are mainly concentrated between

-35 nm, and the relevant specific surface area and pore structure parameters are listed in

Table 1. It can be seen from Table 1 that the Langmuir specific surface area is higher, 205.54

m2/g, the micropore volume is 0.67 cm3 /g, the adsorption volume is 1.19 cm3 /g, the molar

volume of a-pinene gas molecule is 154.9 cm3/mol, and the molecular weight is 136.23 g/mol;

therefore, the molecular molar volume of a-pinene gas is 1.137 cm3 /g, which is consistent

with the cumulative adsorption volume of the La-MOFs-1 intelligent adsorption material of

1.19 cm/g, and is beneficial to the conduct of the adsorption reaction.

[0090] Table 1 Pore Size Distribution and Specific Surface Area of The La-MOFs intelligent

Adsorption Material

[0091]

BET Langmuir Cumulative Average Micropore Micropore Mesopore Specific Specific Adsorption Pore Sample Volume Diameter Diameter Surface Surface Volume Diameter (cm 3/g) (nm) (nm) Area Area (cm 3 /g) (nm) (m 2/g) (m 2/g)

La-MOFs 1.19 0.67 17.27 0.86 15.07 153.76 205.54

[0092] Embodiment 23: SEM Analysis

DESCRIPTION

[0093] The Scanning Electron Microscope (SEM) image of the La-MOFs-1 intelligent

adsorption material is shown in FIG. 8. It can be seen from thefigure that the La-MOFs-1

intelligent adsorption material is composed of a large number of irregular laminar or cluster

structures, and the surface has porous and pore structure morphology, which greatly increases

the specific surface area and porosity of La-MOFs-1, and is conducive to the adsorption of

a-pinene gas molecules with corresponding pore sizes.

[0094] Embodiment 24: TGA Analysis

[0095] The Thermo Gravimetric Analysis (TGA) diagram of the La-MOFs-1 intelligent

adsorption material is shown in FIG. 9. It can be seen form FIG. 9 that the TGA curve

distribution of the La-MOFs intelligent material is not uniform, the reason may be that when

the natural biomass material methyl-a-D-galactopyranoside reacts with the organic

compound phthalic anhydride, the structure of the obtained ligand GE and the ratio of the

coordination between GE and the rare earth metal La" solution are different, and the

obtained La-MOFs-1are diverse. It can be seen from the figure that the weight loss of

La-MOFs-1 is divided into three stages; after 630 °C , most of the remaining mass is

lanthanum nitrate oxide. The first stage of weight loss is caused by the evaporation of water

or crystal water in the structure of La-MOFs-1 and small solvent molecules in the pores

under heated conditions; the second stage of weight loss is mainly caused by the

decomposition of sugar rings and the decomposition of groups in a low-polarity chemical

environment; the third stage of weight loss is caused by the thermal decomposition of

aromatic rings and groups in a high-polarity chemical environment. It can be seen from the

above analysis that the overall thermal stability of the La-MOFs-1 intelligent adsorption

material has good thermal stability within 50°C -200°C, but the overall thermal stability of the

whole process is not high.

[0096] According to the analysis of FTIR and EDS diagrams, molecular rearrangement and

coordination self-assembly reactions have occurred between the organic ligands GE and La";

according to the analysis of specific surface area and average pore size, the La-MOFs-1

intelligent adsorption material belongs to mesoporous and microporous adsorption material,

comprising some microporous pores; according to the results of SEM analysis, the surface of

the La-MOFs-1 intelligent adsorption material is rough; the Langmuir specific surface area is

DESCRIPTION 205.54 m 2/g, the aperture and pore volume size, namely, the micropore volume is 0.67 cm/g

the accumulative adsorption volume is 1.19 cm3 /g, the molar volume of a-pinene gas

molecule is 1.137 cm3/mol, which is consistent with the cumulative adsorption volume of the

La-MOFs-1 intelligent adsorption material, and is beneficial to the conduct of the adsorption

reaction. The bio-friendly raw materials methyl-a-D-galactopyranoside and phthalic

anhydride are used, the ligand GBE is prepared under neutral and alkaline conditions, and the

La-MOFs-1 intelligent adsorption material obtained by the coordination self-assembly

reaction with La+ has good thermal stability within 50 °C -200 °C . Based on the above

characterization results, it can be known that the La-MOFs-1 intelligent adsorption material

has successfully achieved the expected design purpose and requirements for adsorbing

a-pinene gas.

[0097] 3. Adsorption of a-Pinene in Wood Drying VOCs by the La-MOFs Intelligent

Adsorption Material

[0098] Principle of Adsorption Experiment

[0099] Accurately weighing a certain amount of the La-MOFs intelligent adsorption material

and placing it in the test position of the instrument (3H-2000P, multi-station gravimetric

vapor adsorption instrument, Best Instrument Technology Co., Ltd., Beijing); after the

La-MOFs intelligent adsorption material is heated and degassed in vacuum, the sample

chamber is in a vacuum environment; the adsorbed benzene gas evaporates from the liquid in

the reagent tube to become vapor; after being adsorbed by the La-MOFs material, the weight

change of the La-MOFs sample before and after adsorption under a certain relative partial

pressure is weighed by a microbalance to measure the amount of adsorption and desorption

of the specific gas by the sample. The adsorbate is the same gas. Up to four samples can be

tested in parallel in one adsorption experiment, and the average value is used.

[0100] Principle of Desorption Experiment

[0101] The desorption process is the opposite of the adsorption process. The desorption

process is that when the relative partial pressure (P/Po) of gas gradually decreases from the

optimal value of 0.95 to the relative partial pressure of 0 during the adsorption experiment

(specific operation: a vacuum pump is used to extract part of the benzene gas from the

instrument to reduce the partial pressure, and at the same time the adsorption quantity is also

DESCRIPTION reduced, and the desorption quantity is correspondingly increased.). When the partial

pressure drops to a certain level, measure the adsorption quantity at this time by weighing,

which is the desorption quantity of the material to the gas.

[0102] Embodiment 25: Adsorption of a-Pinene by the La-MOFs Intelligent Adsorption

Material

[0103] FIG. 10 is the curve of the influence of La-MOFs on the adsorption quantity of

a-pinene when the preparation time of GE is different. It can be seen from FIG. 10 that in the

adsorption process, when the relative partial pressure (P/Po) is 0.95, and the molar ratio of

La" to the ligand GE is 1:3, under the condition that the molar ratio of GE's synthetic raw

material methyl-a-D-galactopyranoside and phthalic anhydride is 1:3, 1:4, and 1:5, it shows

that when the GE preparation time is 9 hours, the adsorption quantity of the three intelligent

adsorption materials on a-pinene is higher than that at 8 hours.

[0104] Embodiment 26: Influence of the Feeding Molar Ratio of the Two Raw Materials for

the Preparation of GE on the Adsorption Quantity of a-Pinene

[0105] FIG. 11 is a curve of the influence of the molar ratio of the two ligand raw materials

on the adsorption quantity of a-pinene when the preparation time of GE is 9 hours. It can be

seen from FIG. 11 that when the relative partial pressure (P/Po) of the adsorption process is

0.95, the molar ratio of La" to the ligand GE is 1:3, and the preparation time of GE is 9 hours,

under the condition that the molar ratio of the synthetic raw material

methyl-a-D-galactopyranoside and phthalic anhydride of GE is 1:5, the obtained La-MOFs-1

intelligent adsorption material has the best adsorption effect on a-pinene than La-MOFs-4

and La-MOFs-5.

[0106] Embodiment 27: Influence of the Molar Ratio of La" to GBE on the Adsorption

Quantity of a-Pinene

[0107] FIG. 12 is a curve showing the influence of a-pinene gas adsorption quantity when the

molar ratio of La" to GE is different when the preparation time of GE is 9 hours. It can be

seen from FIG. 12 that when the relative partial pressure (P/Po) of the adsorption process is

0.95, the preparation time of GE is 9 hours, and the molar ratio of the synthetic raw material

methyl-a-D-galactopyranoside and phthalic anhydride of GE is 1:5, under the condition that

the molar ratio of La" to GE is 1:3, the prepared La-MOFs-1 intelligent adsorption material

DESCRIPTION has higher adsorption quantity for a-pinene than La-MOFs-14 and La-MOFs-15 materials,

and the maximum adsorption quantity is 178.7220 mg/g..

[0108] 4. Adsorption Comparison of the La-MOFs Intelligent Adsorption Material on Other

Wood Drying VOCs Gas

[0109] Comparative Embodiment 1: Adsorption of p-Pinene Gas by the La-MOFs Intelligent

Adsorption Material

[0110] FIG. 13 is the curve of the influence of the La-MOFs-1 intelligent adsorption material

on the adsorption quantity of p-pinene under different gas relative partial pressure conditions.

It can be seen from FIG. 13 that when the adsorption conditions are optimal: the preparation

time of GE is 9 hours, the molar ratio of the synthetic raw material

methyl-a-D-galactopyranoside and phthalic anhydride of GE is 1:5, the molar ratio of La" to

GE is 1:3, and the relative partial pressure (P/Po) of the adsorption process is 0.95, the

adsorption quantity of the La-MOFs-1 intelligent adsorption material for j-pinene is the

maximum value of 148.0560 mg/g.

[0111] Comparative Embodiment 2: Adsorption of Carbon Tetrachloride by the La-MOFs

Intelligent Adsorption Material

[0112] FIG. 14 is the curve of the influence of the La-MOFs-1 intelligent adsorption material

on the adsorption quantity of carbon tetrachloride under different gas relative partial pressure

conditions. It can be seen from FIG. 14 that when the adsorption conditions are optimal: the

preparation time of GBE is 9 hours, the molar ratio of the synthetic raw material

methyl-a-D-galactopyranoside and phthalic anhydride of GBE is 1:5, the molar ratio of La"

to GE is 1:3, and the relative partial pressure (P/Po) of the adsorption process is 0.95, the

adsorption quantity of the La-MOFs-1 intelligent adsorption material for carbon tetrachloride

is the maximum value of 154.3750 mg/g.

[0113] Comparative Embodiment 3: Adsorption of Benzene by the La-MOFs Intelligent

Adsorption Material

[0114] FIG. 15 is the curve of the influence of the La-MOFs-1 intelligent adsorption material

on the adsorption quantity of benzene under different gas relative partial pressure conditions.

It can be seen from FIG. 15 that when the adsorption conditions are optimal: the preparation

time of GE is 9 hours, the molar ratio of the synthetic raw material

DESCRIPTION methyl-a-D-galactopyranoside and phthalic anhydride of GE is 1:5, the molar ratio of La" to

GE is 1:3, and the relative partial pressure (P/Po) of the adsorption process is 0.95, the

adsorption quantity of the La-MOFs-1 intelligent adsorption material for benzene is the

maximum value of 2.7930 mg/g.

[0115] According to FIG. 10-15, when it is in the optimal preparation conditions: the relative

partial pressure (P/Po) of the adsorption process is 0.95, the preparation time of GE is 9 hours,

the feeding molar ratio of the two synthetic raw materials (methyl-a-D-galactopyranoside and

phthalic anhydride) is 1:5, and the molar ratio of the central rare earth ion La" to the ligand

GE is 1:3, it can be seen from the comparison of the prepared La-MOFs-1 intelligent

adsorption material to the specific VOCs gas (a-pinene, p-pinene, carbon tetrachloride, and

benzene) released in domestic Pinus sylvestris high/normal temperature drying process that

the adsorption quantity of the La-MOFs intelligent adsorption material to a-pinene gas is the

maximum. Therefore, the La-MOFs intelligent adsorption material is a targeted adsorption

material for a-pinene gas. The above experimental data analysis can lay a certain theoretical

foundation for the treatment of VOCs gaseous pollutants released in wood drying industry.

[0116] Comparative Embodiment 4: Comparative Data of Adsorption Capacity of a-Pinene

Gas with Different Materials

[0117] Table 2 shows the comparison of the maximum adsorption quantity data of a-pinene

with several different adsorbents.

[0118] Table 2 Comparison Data of Adsorption Quantity of a-Pinene with Different

Adsorbents

[0119]

Maximum Adsorption Quantity of a-Pinene Adsorbents (mg/g) La-MOFs-1 Intelligent Adsorption Material 178.7220

Nd-MOFs 42.4350

Ce-MOFs 57.6780

Nano-Lignocellulose/Montmorillonite 16.6100 Composite Adsorption Material

DESCRIPTION

[0120] It can be seen from the comparison value of the maximum adsorption quantity of a-pinene with four different adsorption materials in Table 2 that the new La-MOFs-1 intelligent adsorption material designed in the application has a significantly stronger adsorption quantity for a-pinene gas, which is one of the specific VOCs gases released in domestic Pinus sylvestris high/normal temperature drying process, than other adsorption materials. Therefore, the La-MOFs-1 intelligent adsorption material provided in the invention has broad application prospects in the treatment of a-pinene gas released during industrial wood high/normal temperature drying process.

[0121] Summary

[0122] The research on the adsorption performance of the La-MOFs-1 intelligent adsorption material synthesized in the application on a-pinene, which is one of the specific VOCs gases released during domestic Pinus sylvestris high/normal temperature drying process, shows that: the adsorption performance of the La-MOFs-1 intelligent adsorption material for a-pinene is affected by the preparation time of the ligand GE, the molar ratio of the two ligand raw materials, the molar ratio of the central ion La" to the ligand GE, the relative partial pressure of the gas in the adsorption experiment, and other factors. The experimental results show that with the increase of the relative partial pressure of the gas during the adsorption experiment, the adsorption quantity of the La-MOFs-1 intelligent adsorption material of a-pinene gas gradually increases; the optimal preparation process parameters of the La-MOFs-1 intelligent adsorption material are: the relative partial pressure (P/Po) of the adsorption process is 0.95, the preparation time of the ligand GE is 9 hours, the feeding molar ratio of the two synthetic raw materials (methyl-a-D-galactopyranoside and phthalic anhydride) is 1:5, and the molar ratio of La" to GE is 1:3. The new La-MOFs-1 intelligent adsorption material prepared under the above optimal conditions has a maximum adsorption quantity of 178.7220 mg/g for the specific a-pinene gas released during domestic Pinus sylvestris high/normal temperature drying process.

Claims (5)

1. CLAIMS 1. A preparation method of a special rare earth metal La-MOFs adsorption material for

   a-pinene targeted intelligent adsorption, comprising the following steps:

   first, synthesis of methyl-a-D-galactopyranoside aromatic acid ester (GE): pouring

   phthalic anhydride into a container, adding acetone, magnetically stirring, then adding

   methyl-a-D-galactopyranoside, heating up to 62-70°C; the mixture is refluxed under stirring

   and heating; cooling the obtained liquid to room temperature, adding P 2 0 5 to dry and filter,

   and evaporating the obtained filtrate to remove the solvent acetone to obtain a colorless

   viscous liquid GE;

   second, synthesis of the La-MOFs intelligent adsorption material: using the solvent

   synthesis method; placing the ligand GE obtained in the previous step in a container, and

   adding acetone to fully dissolve it to obtain a GE solution; dissolving lanthanum nitrate in

   distilled water to obtain a lanthanum nitrate solution; adding the GE solution and the

   lanthanum nitrate solution into the container in a volume ratio of 1:1-5:1, mixing uniformly,

   and magnetically stirring, then adding triethylamine dropwise to adjust the pH of the solution

   to 7.0-8.0, stirring at room temperature, and filtering the lanthanum nitrate/GE mixture in

   vacuum; the obtained solid is the La-MOFs intelligent adsorption material.
2. 2. The preparation method of a special rare earth metal La-MOFs adsorption material for

   a-pinene targeted intelligent adsorption according to claim 1, wherein in the first step, the

   adding amount ratio of phthalic anhydride and methyl-a-D-galactopyranoside is 1:1-5:1; the

   adding amount of the catalyst triethylamine is 5-15 mL.
3. 3. The preparation method of a special rare earth metal La-MOFs adsorption material for

   a-pinene targeted intelligent adsorption according to claim 1, wherein in the first step, the

   magnetic stirring temperature when the phthalic anhydride is dissolved is 40-50°C; the time

   for heating the mixed solution to reflux is 8-10 hours.
4. 4. The preparation method of a special rare earth metal La-MOFs adsorption material for

   a-pinene targeted intelligent adsorption according to claim 1, wherein in the second step, the

   concentration of the GE solution is 0.10-0.35 g/mL; the concentration of the lanthanum

   nitrate solution is 0.10-0.30 g/mL, and the stirring time when adding triethylamine is 3.0-5.5

   hours.
5. 5. A special rare earth metal La-MOFs adsorption material for a-pinene targeted

   CLAIMS intelligent adsorption prepared by the method of any one of claims I to 4.

   D R AW I N G S 24 Dec 2020 2020104343

   FIG. 1

   FIG. 2

   FIG. 3

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   FIG. 4

   FIG. 5

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   FIG. 6

   FIG. 7

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   FIG. 8

   FIG. 9

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   FIG. 10

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   FIG. 11

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   FIG. 12

   FIG. 13

   D R AW I N G S 24 Dec 2020 2020104343

   FIG. 14

   FIG. 15