CN-117101422-B - Preparation method of Zr-BDC film and organic matter separation application

Abstract

The invention provides a preparation method of a Zr-BDC film and an organic matter separation application. The method directly uses zirconium propoxide as the sole zirconium source in the mother liquor for the first time, synthesizes the continuous Zr-BDC film by a solvothermal method, controls the content of a metal source in the mother liquor to be extremely low, ensures that the film thickness is still thinner after three solvothermal growth, and is favorable for realizing the preparation of the high-flux film. The ligand/metal molar ratio used in the present invention is as high as 20, providing the use of Zr-BDC membranes with fewer defective sites for MeOH/MTBE separation. The Zr-BDC film prepared by the invention shows the optimal MeOH/MTBE separation performance, at 40 ℃, 5wt.% MeOH/MTBE is separated, the film flux can reach 5.68 kg.m ‑2 ·h ‑1 , the separation factor is as high as 25802, and the operation stability is more than 5 days.

Inventors

• LIU XINLEI
• LUO CHENGLIAN

Assignees

• 天津大学

Dates

Publication Date

20260508

Application Date

20230810

Claims (3)

1. 1. A preparation method for separating a methanol/methyl tertiary butyl ether Zr-BDC membrane is characterized by preparing the Zr-BDC membrane by a three-time solvothermal method, and comprises the following steps: 1) Dispersing an organic ligand and zirconium propoxide solution in a mixed solvent of methanol, N-dimethylformamide and acetic acid, and performing ultrasonic dispersion at room temperature to prepare a synthetic solution; 2) Placing a porous alpha-Al 2 O 3 carrier in a reaction kettle, pouring the synthetic solution prepared in the step 1), reacting for 10-12 hours at 110-130 ℃, flushing particles scattered on the surface of the film by using ethanol, soaking the film in the ethanol, and naturally drying at room temperature to obtain a seed crystal layer film; 3) Placing the seed crystal layer film obtained in the step 2) in a reaction kettle, pouring the freshly prepared synthetic liquid, reacting at 110-130 ℃ for 48+/-2 h, flushing particles scattered on the surface of the film by using ethanol, soaking the film in the ethanol, and naturally drying at room temperature to obtain a film subjected to secondary solvothermal growth; 4) Placing the film obtained in the step 3) after the secondary solvothermal growth in a reaction kettle, pouring the freshly prepared synthetic solution, reacting for 20-30 hours at 110-130 ℃, flushing particles scattered on the surface of the film by using ethanol, soaking the film in the ethanol overnight, and naturally drying at room temperature to obtain the Zr-BDC film after the tertiary solvothermal growth; The organic ligand is terephthalic acid or amino terephthalic acid, the molar ratio of the organic ligand to zirconium propoxide is 2:0.2-0.1, the molar ratio of the mixed solvent methanol, N-dimethylformamide and acetic acid is 7.6:4:1, and the molar ratio of acetic acid to zirconium propoxide is 100:0.2-0.1.
2. 2. The method for preparing a Zr-BDC film according to claim 1, wherein the step 2) or 3) is naturally dried at room temperature for 6 to 24 hours.
3. 3. The method for preparing a Zr-BDC film according to claim 1, wherein the step 4) is naturally dried at room temperature for 24 to 48 hours.

Description

Preparation method of Zr-BDC film and organic matter separation application Technical Field The invention relates to the technical field of membrane preparation, in particular to a novel method for preparing a zirconium-based-phthalic acid (Zr-BDC) membrane, which is suitable for separating an organic-organic mixture by a pervaporation membrane technology. In particular to a preparation method of a Zr-BDC film and application of organic matters in separation. Background Methyl tert-butyl ether (MTBE) is an ideal blending component for producing lead-free, high-octane and oxygenated gasoline, and is an important chemical raw material. In the production of MTBE, which involves mainly the reaction of isobutylene with methanol (MeOH), an excessive amount of methanol is usually added to increase the conversion rate of the reaction, which inevitably causes separation problems, whereas 14.3wt.% of methanol can form an azeotrope with methyl tert-butyl ether at 51 ℃ under normal pressure, increasing the difficulty of separation thereof. The principle of pervaporation is to use the vapor pressure difference at two sides of the membrane as driving force, and to realize separation by means of the difference of adsorption and diffusion rates of two components in the membrane material, the separation effect is not limited by the gas-liquid balance of the components, and the pervaporation method is very suitable for separating near-boiling matters and constant-boiling matters. Pervaporation technology is widely applied to dehydration of organic solvents and separation of organic matters and organic mixtures in water, wherein the preparation of alcohol-ether separation membranes is a subject of attention of a plurality of researchers. MeOH/MTBE separation membrane materials include organic, inorganic and hybrid organic/inorganic membranes. The organic film has lower preparation cost, but is easy to expand, has poor stability and is difficult to overcome the trade-off effect between permeability and selectivity. Currently commercial polymer membranes (PERVAP 2256) are used to separate the system, but the membrane performance is not high (flux <1 kg-m -2·h-1, selectivity < 200). Although the inorganic membrane has excellent separation performance and better stability, the cost is higher, and the preparation process is relatively complex, so the development of a membrane with the advantages of both the organic membrane and the inorganic membrane is one of the hot spots in the research of the current membrane technical field. Zr-BDC is a highly stable organic/inorganic hybrid membrane material by constructing a high connectivity coordination structure, and has great application prospect in membrane separation of organic mixtures. A typical formula for preparing the Zr-BDC film uses zirconium chloride as a metal source, however, the zirconium chloride is unstable at normal temperature and normal pressure, is easy to absorb moisture, has strong hygroscopicity, is difficult to store, is easy to generate safety problems, and generates volatile organic compound hydrogen chloride (HCl) in the film preparation process. There is therefore a need to explore methods for preparing Zr-BDC films of lower thickness, continuous, and defect free, using other zirconium sources. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a novel preparation method of a Zr-BDC film. The method controls the content of the metal source in the solution to be extremely low (1:12600), so that the film thickness is thinner (500 nm) even after three solvothermal growth. On one hand, nutrition required in the film forming process can be supplemented, on the other hand, nucleation and growth can be independently controlled, the film structure can be regulated and controlled, and the film forming repeatability can be improved. At the same time, the high stability of the Zr-BDC membrane and the suitable pore size facilitate the methanol/methyl tert-butyl ether (MeOH/MTBE) separation. In order to achieve the aim, the invention provides a preparation method of a Zr-BDC film, which comprises the following steps of: A preparation method of a Zr-BDC film comprises the following steps of: 1) Dispersing an organic ligand and zirconium propoxide solution in a mixed solvent of methanol, N-dimethylformamide and acetic acid, and performing ultrasonic dispersion at room temperature to prepare a synthetic solution; 2) Placing a porous alpha-Al 2O3 carrier in a reaction kettle, pouring the synthetic solution prepared in the step 1), reacting for 10-12 hours at 110-130 ℃, flushing particles scattered on the surface of the film by using ethanol, soaking the film in the ethanol, and naturally drying at room temperature to obtain a seed crystal layer film; 3) Placing the seed crystal layer film obtained in the step 2) in a reaction kettle, pouring the freshly prepared synthetic solution, reacting for 48+/-2 hours at 110-130 ℃, flushing pa