Xylene vapor mixture separation in nanocomposite MFI-alumina tubular membranes: influence of operating variables

Daramola, M. O., Burger, A. J., Pera-Titus, M., Giroir-Fendler, A., Lorenzen, L. and Dalmon, J. -A. 2010. Xylene vapor mixture separation in nanocomposite MFI-alumina tubular membranes: influence of operating variables. Separation Science and Technology 45 (1) , pp. 21-27. 10.1080/01496390903402141

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Abstract

In this study, we present the results of a preliminary investigation on the influence of operating variables (temperature, sweep gas flow rate, and total feed vapor pressure) on xylene vapor mixture separation using tubular nanocomposite MFI-alumina zeolite membrane prepared by the pore-plugging synthesis technique. Within the detection limit of our analytical system, neither m- nor o-xylene was detected in the permeate stream, the membranes displaying therefore “infinite” p-xylene selectivity. The mixture's p-xylene flux displayed a maximum value of ca. 3.5 µmol·m−2·s−1, corresponding to a mixture permeance of 11 nmol·m−2·s−1·Pa−1, at 473 K and for a feed composition 0.63 kPa p-xylene/0.27 kPa m-xylene/0.32 kPa o-xylene, being almost unchanged for sweep gas flow rates (N2) higher than 20 mL(STP)/min and increasing with the total xylene vapor pressure at 1 : 1 : 1–3 p/m/o-xylene composition. The experimental p-xylene fluxes can be well predicted by a Maxwell-Stefan model, as expected for a mass transfer process driven by competitive adsorption / surface diffusion. Unlike film-like MFI membranes, the membranes presented here preserved their selectivity to p-xylene for total xylene pressures as high as 150 kPa. This behavior is attributed to the intimate contact between the alumina confining pores and MFI nanoparticles, reducing long-term stresses and thus preventing distortion of the MFI framework during p-xylene adsorption. These results open up potential applications of nanocomposite MFI-alumina for selective p-xylene separations at high loadings, for instance in pervaporation, where the use of film-like MFI membranes is discouraged.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Publisher:	Taylor & Francis: STM, Behavioural Science and Public Health Titles
ISSN:	0149-6395
Date of Acceptance:	31 August 2009
Last Modified:	13 Oct 2020 13:15
URI:	https://orca.cardiff.ac.uk/id/eprint/135411

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