Tailored hydrophobic carbon molecular sieve membrane||Tailored hydrophobic carbon molecular sieve membrane

It is provided a hydrophobic carbon molecular sieve membrane (CMSM) characterized by comprising pores with a pore size distribution in which at least 20 % of the pores have a pore size from 0.5 to 0.6 nm, measured by perm-porosimetry; and having a C/O ratio higher than 8 and a C/H ratio higher than 20; the membrane being obtainable by dip- coating a support with a dipping solution comprising a carbon precursor, a non-aqueous solvent, a curing agent, and a pore forming agent, wherein the pore forming agent is in an amount from 0.5 wt% to 8 wt% related to the weight of carbon precursor; followed by carbonization at a temperature higher than 700 ºC and lower than 1000 ºC; and wherein the carbon molecular sieve membrane has a higher hydrophobicity than a membrane prepared by the same process but without the addition of the pore forming agent. It is also provided a method for the preparation of the CMSM, and its use for the selective separation of propionic acid from a mixture with water and acetic acid and as a membrane reactor or part of a membrane reactor.