Preparation Of PEBA2533/Nano-5A Molecular Sieves Mixed Matrix Membranes And The Study Of Their Separation Performance Of Ethylene/Propylene Mixture

Ethylene and propylene are important chemical raw materials,the main sources of ethylene and propylene include: oil brain cracking,coal conversion,natural gas synthesis.In the process of industrial production,the separation process of ethylene and propylene mixture is cryogenic separation,and its energy consumption accounts for more than 2/3 of the whole production process.The energy consumption of membrane separation technology is low,so this method has drawn more attention.In this paper,a mixed gas of ethylene and propylene was separated by preparing a PEBA / nano-5A molecular sieve mixed matrix membrane.Firstly,the effects of n(H2O):n(Na2O),crystallization time,aging time,dropping method and basic condition on the particle size of molecular sieves were investigated in the preparation of 5A molecular sieves with small particle size.The PEBA / 5A molecular sieve mixed matrix membrane was prepared by doping the 5A molecular sieve as inorganic filler particles into the PEBA matrix film,and the mixture was characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM)were used to analyze the structure of the membrane.Finally,the mixed matrix membranes were used to seperate ethylene and propylene mixture gas at a temperature of-35 ? ~ 20 ? and pressure of 0.2MPa ~ 0.4MPa.The specific results are as follows:1.Preparation of 5A molecular sieves with small particle size.The effects of n(H2O):n(Na2O),aging time,crystallization time,dropping method,ion exchange frequency and molecular sieve activation temperature on the particle size were investigated.N(H2O):n(Na2O)=70,aged 2d,crystallized for 6h,and activated by four times of solution at a temperature of 310 ? to obtain a particle size of about 500 nm 5A molecular sieve.2.Preparation of PEBA / 5A molecular sieve mixed matrix membrane.In the process of preparing a mixed matrix membrane,the chemical properties of the substance did not change,and a simple physical fusion.3.The effect of operating conditions on the separation performance of PEBA / 5A molecular sieve mixed matrix membrane.The PEBA / 5A molecular sieve mixed matrix membrane was prepared by doping the 5A molecular sieve with large particle size into the PEBA matrix material and under the condition of blast drying.The effects of the mixed matrix membrane mixed with 1: 1 molar ratio ethylene / propylene mixed gas at the temperature(-35 ? ~ 20 ?)and pressure(0.2MPa ~ 0.4MPa)were investigated.When the temperature is-35 ? and the pressure is 0.2MPa,the separation performance of PEBA / 5A molecular sieve is the best.The separation factor is 3.96,the permeability coefficient of ethylene is 736 Barrer,and the permeability coefficient of propylene is 2914 Barrer.4.Effects of Different Drying Methods on the Separation Performance of Mixed Matrix Membrane.It was investigated that a large particle size 5A molecular sieve was doped as an inorganic filler particle into a mixed matrix membrane and dried in diffrerent way respectively.At a pressure of 0.2MPa and a temperature of-35 ?,the separation factor of the mixed matrix membrane prepared by vacuum drying was4.09,and the separation effect was better.5.The effect of particle size on the separation performance of mixed matrix membrane.The mixed matrix films prepared on the particle size of the doped 5A molecular sieves(1.5?m,500nm)at the pressure of 0.2MPa and vacuum drying were investigated.The mixed matrix membrane separation factor prepared by doping 500 nm 5A molecular sieves was4.36.6.Effect of doping amount on the separation performance of mixed matrix membrane.When the doping amount of 5A molecular sieve with particle size of 500 nm was 2wt%,3wt%,5wt%,6wt%,7wt% and 10wt%,the prepared PEBA / 5A molecular sieve mixed matrix membrane was prepared at a temperature of-35 ? ~ 20 ?,the pressure of 0.2 ~0.4MPa,the evaluation of its 1: 1 ethylene propylene mixed gasseparation performance.The permeability coefficient of the mixed matrix membrane to ethylene and propylene gas increases,and the separation factor increases first and then decreases.At-35 ?,0.2MPa separation factor of 4.36,ethylene permeability coefficient of 639 Barrer,propylene coefficient of 2786 Barrer.