Determining the dehydration performance of a hydrophobic DDR zeolite membrane
Advancing the chemical engineering fundamentals
Membranes and Membrane Science - I (T2-8a)
Keywords: DDR, zeolite, membrane, dehydration, pervaporation
The polarity of a zeolite is an important parameter determining the transport and separation properties in zeolite packed beds and membranes. Conventionally hydrophilic membranes are used for dehydration of solvents. For zeolite membranes this usually implies a low silica to aluminium ratio. The high aluminum content, however, results in decreased chemical stability [1] and reduced membrane quality causing intercrystalline transport [2].
All-silica DDR is a hydrophobic zeolite, with a pore size of 3.6 x 4.4 Å, able to separate water from many solvents based on size exclusion [3]. All-siliceous DDR membranes (NGK, Japan) have been used to study the permeation of pure water, methanol and ethanol, as well as water/ethanol mixtures in pervaporation mode. The membrane showed to be insensitive to increased feed side pressure (up to 12 bar), indicating the absence of viscous flow contribution. High fluxes of pure water (up to 4.6 kg.m-2.hr-1) and excellent selectivities for water/ethanol (up to 10.000) have been measured. However, the presence of ethanol strongly influences the water permeance, and vice versa. The permeation results are modeled using Maxwell-Stefan based equations.
1 Y. Cui, H. Kita, and K. I. Okamoto, Journal of Membrane Science, vol.236, 17 (2004)
2 M. Noack, P. Kolsch, V. Seefeld, P. Toussaint, G. Georgi, and J. Caro, Microporous and Mesoporous Materials, vol.79, 329 (2005)
3 Yajima, K., Nakayama, K., Niino, M., Tomita, T., and Yoshida, S., Proceedings of the 9th ICIM9, 401, (2006)
Presented Tuesday 18, 16:00 to 16:20, in session Membranes and Membrane Science - I (T2-8a).
