Preparation of carbon molecular sieve membrane derived from phenolic resin over macroporous clay-alumina based support for hydrogen separation

An asymmetric carbon membrane was prepared by coating alcoholic solution of industrial grade phenol formaldehyde novolac resin (PFNR) directly over indigenously prepared macroporous clay-alumina based ceramic support without using any microporous intermediate layer. The initial three coatings of 40 wt% PFNR solution was carried out using vacuum assisted dip coating method followed by fourth coating of same solution by normal dip coating method and final fifth coating of 60 wt% PFNR solution also by normal dip coating method. After each coating, the coated support was air dried in room temperature for 24 h and was subjected to pinhole test with nitrogen gas, failing which the coating process was repeated. The finally coated support was carbonized at 780 A degrees C in nitrogen atmosphere to obtain a layer of carbon molecular sieve membrane (CMSM) over the support. FESEM and EDX analysis confirmed the formation of CMSM membrane directly over the support. HK method of pore size analysis revealed the presence of ultramicropores in the range of 4-8 in the prepared CMSM. Single gas permeation test through the CMSM showed that it exhibits selectivities of 9.00, 14.28 and 10.21 for H-2/N-2, H-2/CO2 and H-2/CH4 systems respectively with H-2 permeability of 27 x 10(-9) mol.m(-2).s(-1).Pa-1.