The Preparation And Gas Separation Properties Of Porous Organic Framework Based Mixed-matrix Membrane

Compared with other separation technique,membrane separation technology has the characteristics of convenient operation,high efficiency,small footprint and low energy consumption.However,the used membrane materials are mostly polymers currently,and because of the dense internal structure of the polymer film,it is usually not possible to have both high permeability and high selectivity,That is,when the permeability is high,the selectivity is low;when the selectivity is high,the permeability is not high.Porous organic skeleton material is a new and excellent porous material with high porosity,low density,large specific surface area and excellent adsorption performance.It is widely used in gas separation,adsorption and storage.The addition of a porous organic skeleton material with high adsorption separation performance but not easy to be formed in the polymer film can have both the easy film-forming property of the polymer material and the selective adsorption separation performance of the porous organic skeleton material.this paper mainly studies the preparation of mixed matrix membrane of porous organic skeleton material and uses it for CO2/N2 and CO2/CH4 separation.The main research contents include:1)Preparation and Separation Performance of Porous organic polymer mixed matrix membrane.The porous organic frameworks(named MA)was synthesized by polycondensation of melamine and terephthalaldehyde.The porous organic framework material MA with high adsorption performance to CO2 was added to the Polysulfone and polydimethylsiloxane matrix to obtain MA/PSF and MA/PDMS mixed matrix membrane,the membrane used for CO2/N2,CO2/CH4 two groups of mixed gas separation test.The results show that MA is a network composed of nanometer spherical particles,and the diameter of the particles is very small.The surface area is 595.8 m2/g,the thermal stability of the material is better,that can achieve the preparation of mixed film on the thermal stability of the filler requirements;in the single component gas separation test of CO2,N2,CH4 for The synthesis of MA/PSF(12 wt%)mixed matrix membrane,the ideal separation index of CO2/CH4 and CO2/N2 reached the maximum,The respectively,2.1 and 5.0,and the CO2 permeation coefficient was only 35 Barrer.In the MA/PDMS(1.2 wt%)mixed matrix membrane test for single component gas separation,CO2/CH4 and CO2/N2 The ideal separation index to reach the maximum,respectively,4.4 and 16.1,CO2 permeability coefficient was 5512 Barrer.The separation indices of CO2/CH4 and CO2/N2 were 6.0 and 19.2,respectively,the CO2 permeability reached up to 8100 Barrer,much higher than the pure PDMS membrane.The MA/PDMS(1.2 wt.%)MMM surpasses the Roberson upper bound for CO2/N2 separation..2)The coated matrix film was prepared by coating with a PDMS on the surface of the MA,and the mixture was filled into the PDMS.The mixed matrix membrane was prepared by the same method and the separation performance of the mixed matrix membrane was studied.The experimental results show that The internal pore structure of the MA after the coating did not change significantly,and the mixed matrix membrane of Coating-MA/PDMS is more time-saving than that of MA/PDMS,and the separation index is almost unchanged.At the same time,when the filling amount is too large,the separation factor of the mixed matrix membrane does not decrease rapidly.This may be because the MA material of the PDMS on the surface coating can be combined with the PDMS,due to the large gap between the two phases And the defects were filled.