ZSM-5 zeolite membranes prepared from a clear template-free solution

Template-free nanosized ZSM-5 seeds were prepared from commercially available ZSM-5 powder. By use of these seeds, thin and hydrophilic ZSM-5 zeolite membranes were prepared on the outer surface of a porous a-alumina tube in a clear solution free from organic template. The membranes showed high thermal stability to withstand pretreatment at 400 degreesC, At 270 degreesC, the ideal selectivities for H-2/i-butane and N-2/SF6 were 61 and 20, respectively. The membrane was effective to separate butane isomers at high temperatures. The maximum of the n/i-butane ideal selectivity was 36 at 300 degreesC. The separation factors for a 50/50 n/i-butane mixture were as high as 13 in the temperature range from 300 to 400 degreesC. (C) 2003 Elsevier Science Inc. All rights reserved.