Zeolite Hollow Fibers
Taking advantage of coaxial electrospinning, zeolite hollow fibers were fabricated by Jiang and Yu’s group using coelectrospinning followed by calcination, in 2008 (Di et al., 2008). Coreeshell fibers were obtained first, using a suspension of silicalite-1 NPs in PVP/ethanol solution as the outer fluid, while paraffin oil was used as the inner liquid. An appropriate proportion of PVP and silicalite-1 was necessary because the silicalite-1 suspension could not be electrospun alone, while the viscous PVP solution could make the blend feasible for fluent electrospinning and served as an adhesive to bond the silicalite-1 NPs together. By subsequent calcination in air at 550C for 6 h, these composite fibers transformed into zeolite hollow fibers with removal of paraffin oil, tetrapropylammonium hydroxide, and PVP. The zeolite hollow fibers had good mechanical strength with great performance of self-standing. Moreover, the zeolite hollow fibers had a hierarchical intersecting channel structure and rough wall constructed by the NPs. The morphology and chemical composition of the as-spun fibers composed of silicalite-1 and PVP by coelectrospinning are shown in Fig. 5.10.