Preparation Of Polymer-based Composite Membranes And Its Dehydration Performance Of Natural Gas

The presence of water vapor in natural gas may cause corrosion of pipes and equipment,and may even form ice plugs,block pipes,so affect normal gas transmission.Therefore,dehydration is required before natural gas is delivered.Membrane separation method is an effective method for dehydration of natural gas.The key to the membrane separation method is the membrane separation material.The single membrane material originally selected has not been able to meet the separation needs.Organic polymer membranes have trade-offs in permeability and selectivity,while inorganic molecular sieve membranes are expensive to manufacture and prone to defects.The polymer-based composite film combines the advantages of both,which not only improves the gas transportability of the polymer film,but also effectively utilizes the selectivity of the inorganic substance,and has been widely used in the field of gas separation.There have been no reports on the use of polymer-based composite membranes for the dehydration of natural gas.In this paper,a series of cellulose acetate/A zeolite molecular sieve mixed matrix membranes were successfully prepared by phase inversion method using A zeolite molecular sieve as filler.The natural gas dehydration performance of mixed matrix membranes with different molecular sieve content,different molecular sieves types and different film thicknesses was investigated.The res ults showed that when the cation in the molecular sieve was potassium ion,the composite films exhibited superior separation performance.When the KA zeolite molecular sieve loading was 7.5 wt%,the mixed matrix membrane had a selectivity to H₂O/CH₄ of 26.29.And as the thickness of the film increases,the permeability of the film to the gas decreases but the selectivity increases.In addition,the nylon/KAUST-8 composite membranes were prepared by seed pre-coating method.The KAUST-8 loaded on the membrane surface was more,but the presence of pores on the surface resulted in lower selectivity.Stacking of two-layer composite membranes improved gas selectivity.