Development of adsorption selective carbon membrane using cellulose acetate for separation of O2/N2 and C1-C4 hydrocarbons/N2

Abstract

The objective of this study is to develop a new kind of carbon membrane which could separate gas based on the adsorption concept. This study was subjected to encounter challenges imposed by general trade off between permeability and selectivity of membrane. Membrane was prepared from a thermosetting polymer that acts as a carbon precursor in this type of membrane. The membrane is formed by pyrolysis of cellulose acetate supported over a microporous ceramic membrane used for microfiltration at 3000C, 3250C, 3500C, 4000C, 4500C, and 5000C under N2 flowrate equal to 200 ml/min. The membrane then was further subjected to an oxidative treatment at temperature between 1500C to 4000C with an interval of 500C. The pyrolysis temperature was found plays an important role in changing the morphology of the carbon membrane been developed. Increasing the pyrolysis temperature produces more pores with smaller diameter, thus reducing the permeability of the penetrates. The optimum pyrolysis temperature for O2/N2 separation is at 4000C which give the value of the selectivity about 3.92. This value has exceeded an excellent value that is selectivity above 3.0 as suggested by Kulprathinja (1988). A hierarchal way to developed the adsorption selective carbon membrane has been done. The prepared membrane shows high permeabilities and selectivity towards separation of gas mixtures formed by hydrocarbons and N2. Membrane prepared at 4000C was further subjected to an air oxidation at 3000C and gave the value for single gas experiment, C2H6/N2; 2.52, C3H8/N2; 2.44, n-C4H10/N2; 2.35. For binary gas experiment, the selectivity for C2H6/N2; 3.3, C3H6/N2; 14.4, n- C4H10/N2; 26.05. A selective and high permeability carbon membrane based on cellulose acetate could be developed