CN110605097A

CN110605097A - Binder-free MIL-100Cr forming method

Info

Publication number: CN110605097A
Application number: CN201910884500.9A
Authority: CN
Inventors: 杨江峰; 张飞飞; 李晋平
Original assignee: Taiyuan University of Technology
Current assignee: Taiyuan University of Technology
Priority date: 2019-09-19
Filing date: 2019-09-19
Publication date: 2019-12-24
Anticipated expiration: 2039-09-19
Also published as: CN110605097B

Abstract

The invention relates to the field of forming of metal organic framework materials MIL-100Cr, in particular to a method for forming binder-free MIL-100 Cr. The method comprises the following steps: firstly, uniformly mixing MIL-100Cr powder with water, then pelletizing the mixture by a pelletizing machine, and then placing the ball in a 220 ℃ oven for heating for 8 hours to obtain the MIL-100Cr ball. The invention makes full use of the self-adhesive property of the MIL-100Cr material to successfully realize the molding of the MIL-100Cr without adding any adhesive, makes up for the problem of the shortage of the MIL-100Cr molding technology, and does not add any adhesive in the molding process, thereby furthest retaining the gas adsorption and separation performance of the material, having great industrial application prospect and having great guiding effect on the molding of other metal organic framework materials.

Description

Binder-free MIL-100Cr forming method

Technical Field

The invention relates to the field of molding of metal organic framework materials MIL-100Cr, in particular to a method for molding MIL-100Cr without an adhesive.

Background

In a plurality of metal organicAmong frame materials, the MOFs material with unsaturated metal sites is always the focus of research, and due to the strong interaction between the unsaturated metal sites and gas, the MOFs material often has better gas adsorption and separation performance. Wherein, the three-dimensional spatial structure MIL-100Cr formed by piling two hole cages with different sizes is always the key point of research, and after the material is treated by high temperature and high vacuum, water molecules coordinated with a metal center can be fully removed to generate about 1.1-2.6 mmol.g^-1The research shows that the unsaturated metal site pair N in the MIL-100Cr₂Has strong affinity, N at normal temperature and normal pressure₂Has an adsorption capacity greater than CH₄The material has a wide application prospect in the aspects of natural gas denitrification, air separation and the like.

The MIL-100Cr material synthesized in a laboratory at present is a powder crystal, if the powder crystal is directly filled into an adsorption bed, the flow speed of gas to be separated in the bed layer can be greatly reduced, the treatment efficiency is reduced, and a powder adsorbent easily flows out of the adsorption bed along with the gas, so that the loss of the adsorbent and dust pollution can be caused, and the forming of the MIL-100Cr material is an important step in the industrial application of the MIL-100Cr material.

The research of the powder adsorbent forming technology in the field of molecular sieve materials is relatively mature at present, and the powder adsorbent forming technology is mainly formed by bonding in a manner of adding a binder, but when the research on the forming of an MIL-100Cr material is carried out, the fact that the density of the material is low and the adsorption performance of the material is often greatly influenced by using a common binder is discovered, so that the manner of adding the binder for forming is not beneficial to exerting the adsorption and separation performance of the material to the maximum extent.

Disclosure of Invention

The invention provides a binder-free MIL-100Cr molding method on the premise that the MIL-100Cr molding technology is in shortage at present and the defects of adding a binder are large.

The most common method for forming metal organic frame material at present is a method of forming by adding binder, which uses different binders for forming molecular sieve to achieve the purpose of bonding and forming, but in the course of researching the existing research results, it is found that the method of adding binder often greatly reduces the gas adsorption and separation performance of metal organic frame material, mainly because after adding binder, because the metal organic frame material has poor thermal stability, the binder can not be fully burned out by high temperature treatment like molecular sieve, resulting in excessive binder remaining in the formed material, and compared with the binder, the density of metal organic frame material is generally smaller, so the performance of the formed metal organic frame material is greatly reduced compared with the original powder.

The method for molding MIL-100Cr has not been reported at present, and in order to keep the adsorption separation performance of the molded material to the maximum extent in the research process, the inventor firstly thinks whether the material has self-adhesion performance, the MIL-100Cr material is formed by coordination assembly of chromium and trimesic acid, the trimesic acid is rich in carboxyl, the carboxyl can be dehydrated and connected with each other if being fully processed at high temperature, secondly, the existence of defects is inevitable in the process of MIL-100Cr coordination assembly, so that incompletely connected metal chromium centers and carboxyl are inevitably present in the material, and the heating treatment can also promote the reassembly of the incompletely connected metal chromium centers and carboxyl in the material.

Based on the above idea, the inventor has performed a series of verification, and provides the following technical solutions: a method for forming binder-free MIL-100Cr comprises the following steps:

firstly, uniformly mixing MIL-100Cr powder with water, then pelletizing the mixture by a pelletizing machine, and then placing the ball in a 220 ℃ oven for heating for 8 hours to obtain the MIL-100Cr ball.

As a further improvement of the technical scheme of the invention, the mass-volume ratio of the MIL-100Cr powder to the water is 2: 1.

Comparing and analyzing the color and the chemical and physical properties of the molded MIL-100Cr sphere sample prepared by the invention and the unformed original powder, and concluding that: the MIL-100Cr sphere obtained by the method is dark green, the specific surface area of the sphere is not obviously reduced compared with that of the original powder, and the N of the sphere is not obviously reduced₂、CH₄And N₂/CH₄The selectivity is not obviously reduced compared with the original powder, and when the MIL-100C is adoptedWhen the mass volume ratio of the r powder to the water is 2:1, the hardness of the sphere reaches 28N, and the sphere has good mechanical strength.

Further, the surface areas of the MIL-100Cr powder and the molded sphere were calculated, and the detailed data are shown in Table 1.

TABLE 1

In table S_LLangmuir surface area; s_BETSpecific surface area;

in addition, the inventor uniformly mixes 50g of MIL-100Cr powder with water with different volumes, then balls are formed by a pill making machine, the obtained balls are placed into a 220 ℃ oven to be heated for 8 hours, the balls are respectively treated according to the parameters in the table 2, and the hardness of the sample is shown in the table 2 below.

TABLE 2

Serial number	H₂O addition/mL	MIL-100Cr powder addition/g	Hardness of
				1	12.5	50	15N
2	25	50	28N
				3	50	50	17N

Further, the inventor uniformly mixes 50g of MIL-100Cr powder with 25mL of water, 25mL of ethanol and 25mL of methanol respectively, then balling the mixture by a pill making machine, putting the obtained spheres into a 220 ℃ oven for heating and treating for 8 hours, and treating the spheres according to the parameters in the table 2 respectively, wherein the hardness table of the samples is shown in the following table 3.

TABLE 3

Serial number	Solvent(s)	Solvent addition/mL	MIL-100Cr powder addition/g	Hardness of
					1	Water (W)	25	50	28N
2	Ethanol	25	50	13N
					3	Methanol	25	50	11N

Compared with the prior art, the invention has the following beneficial effects: the invention makes full use of the self-adhesive property of the MIL-100Cr material to successfully realize the molding of the MIL-100Cr without adding any adhesive, makes up for the problem of the shortage of the MIL-100Cr molding technology, and does not add any adhesive in the molding process, thereby furthest retaining the gas adsorption and separation performance of the material, having great industrial application prospect and having great guiding effect on the molding of other metal organic framework materials.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic view of the molding method. The pale green powder used in the figure was not subjected to other treatments before molding, the water used for molding was distilled water, the pelletizer used was a tiltable multi-functional pelletizer, and the diameter of the molded spheres was about 2 mm.

FIG. 2 is a schematic diagram showing the comparison of XRD (as synthesized) spectrum of the MIL-100Cr spheres prepared by the present invention and XRD spectrum (simulated) of the original powder by an x-ray diffractometer. The main peak positions of the XRD diffraction peaks of the two are consistent, and the peak intensities are not greatly different, which indicates that the MIL-100Cr powder material is not damaged in the forming process.

FIG. 3 is a comparison graph of the nitrogen adsorption of MIL-100Cr spheres prepared by the invention and the nitrogen adsorption of the MIL-100Cr product of the original powder. The specific surface area of the MIL-100Cr sphere prepared by the method is basically the same as that of the original powder, and further illustrates that the forming method does not damage the original powder material.

FIG. 4 shows MIL-100Cr spheres prepared by the present invention at normal temperature N₂Adsorption and original powder MIL-100Cr product normal temperature N₂The adsorption contrast graph shows that compared with the original powder, the N of the formed sphere is higher than that of the original powder₂The slight decrease in the amount of adsorption was probably due to insufficient activation of the spheres after molding.

FIG. 5 shows MIL-100Cr sphere normal temperature CH prepared by the present invention₄Adsorption and original powder MIL-100Cr product normal temperature CH₄The adsorption contrast graph shows that compared with the original powder, the CH of the formed sphere is shown in the adsorption isotherm₄The adsorption amount is slightly decreased, and the result is associated with N₂The results obtained by normal temperature adsorption were consistent.

FIG. 6 shows the comparison of N at normal temperature₂And CH₄The adsorption isotherm of (a) is fitted with a double langmuir model and then calculated using the IAST theory to obtain N₂/CH₄A selectivity profile. Wherein N is₂And CH₄The volume ratio is 50:50, and the N of the original powder and the molded sphere is compared₂/CH₄The selectivity curve shows that the N of the formed sphere₂/CH₄The selectivity curve is slightly reduced, and the N of the original powder material is greatly reserved₂/CH₄The properties are selected.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

Shaping of MIL-100Cr

Chemical substance material: MIL-100Cr powder, deionized water, absolute ethyl alcohol and absolute methyl alcohol, wherein the dosage is as follows: taking g and ml as measurement unit

Example 1

Uniformly mixing 50g of MIL-100Cr powder (see CN 109535437A for a preparation method) with 12.5mL of deionized water, 25mL of deionized water and 50mL of deionized water respectively, fully kneading to ensure that the water and the powder are fully mixed, and then pelletizing by a pelletizer; and (3) putting all the three spheres obtained in the step (A) into a 220 ℃ oven for heating for 8h, taking out, cooling to normal temperature in an air atmosphere, respectively putting the three prepared MIL-100Cr spheres into three numbered transparent glass containers, and hermetically storing.

Example 2

Respectively and uniformly mixing 50g of MIL-100Cr powder (see CN 109535437A for a preparation method) with 25mL of deionized water, 25mL of anhydrous ethanol and 25mL of anhydrous methanol, fully kneading to ensure that the solvent and the powder are fully mixed, and then pelletizing by a pelletizer; and (3) putting all the three spheres obtained in the step (A) into a 220 ℃ oven for heating for 8h, taking out, cooling to normal temperature in an air atmosphere, respectively putting the three prepared MIL-100Cr spheres into three numbered transparent glass containers, and hermetically storing.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A method for forming binder-free MIL-100Cr is characterized by comprising the following steps:

firstly, uniformly mixing MIL-100Cr powder with water, then balling by a pill making machine, and then placing the ball body in a 220 ℃ oven for heating treatment for 8 hours to obtain the MIL-100Cr ball body.

2. The method of claim 1, wherein the binder-free MIL-100Cr powder to water mass to volume ratio is 2: 1.