Transport Properties of Zeolite Na‐X–Nafion Membranes: Effect of Zeolite Loadings and Particle Size

Abstract

Na-X zeolites particles, synthesized in two size ranges,\ud namely 200–300 nm and 30–100 nm, were used to prepare\ud Nafion/Na-X zeolite composite membranes by recast\ud method. The physical, chemical, and morphological properties\ud of the zeolite powders and composite membranes were\ud examined by XRD, N2 adsorption isotherms, FTIR, SEM,\ud and SAXS analysis. Furthermore, the effect of zeolite particles\ud size and loadings (i.e., 5 and 10% w/w) on the water,\ud methanol, and proton transport properties was investigated.\ud It has been found that the size of the Na-X zeolite particles\ud plays a key role in the proton and methanol transport\ud behavior since it rules the zeolite hydrophilic behavior, the\ud morphology of polymer–filler interphase, and also the nature\ud of water established in the composite membrane.\ud The results show that the membranes loaded with a 5%\ud w/w of submicron-sized Na-X zeolite exhibit a proton conductivity\ud and selectivity significantly higher than Nafion. In\ud particular the proton conductivity at 120 °C is around eight\ud times and the selectivity at 25 °C is around 40% higher than\ud those exhibited by recast Nafion

Enhancement of Nafion based membranes for direct methanol fuel cell applications through the inclusion of ammonium-X zeolite fillers

“…1; The XRD patterns match the patterns obtained for submicron and nano Na-X which can be assigned to hydrated Na-X with a nominal composition of Na 88 (H 2 O) 220 [Si 104 Al 88 O 384 ] (pdf: 00-037-0218) [17] (see Supplementary Fig. S1).…”

“…The membranes loaded with a 5 wt.% of submicron-sized Na-X zeolite exhibit a selectivity value at 25 C that is around 40% higher, due to the hindered transport of methanol through the zeolite, than that exhibited by recast Nafion [17]. The effect of particle size has also had been studied using phosphotungstic acid as filler, and the results showed that the performance of Nafion/phosphotungstic acid composite membranes was dependant on the particle size of the phosphotungstic acid [18].…”

“…Comparatively, the former one is more favored because of simple preparation and improved performances. Numerous inorganic materials had been reported as effective fillers to improve the properties of Nafion, including TiO 2 [7], organomodified silica [9], zirconium phosphate [10], SiO 2 [15], phosphotungstic acid [16], and Na-X zeolite [17].…”

A Nafion-Ceria Composite Membrane Electrolyte for Reduced Methanol Crossover in Direct Methanol Fuel Cells

“…Figure 1a shows the XRD pattern which displays diffraction peaks at 2θ of 28 [23,24]. By using the Scherrer formula, the crystallite size of CeO 2 was calculated from the (111) diffraction and it is found to be 52.62 nm.…”

“…[28]. The addition of nanofillers to the Nafion matrix without any phase separation increases the proton conductivity due to the higher water uptake capacity and hinders the methanol transport across the membrane.…”