Meso-Porous Alumina Capillary Tube as a Support for High-Temperature Gas Separation Membranes by Novel Pulse Sequential Anodic Oxidation Technique

Abstract

A meso-porous anodic alumina capillary tube (MAAC) having highly oriented radial meso-pore channels with a minimum diameter of 3 nm has been successfully synthesized using a novel pulse sequential anodic oxidation technique at 100 Hz of pulse frequency. A value resulting in a high channel-pore formation rate at 1 V of the pulse sequential voltage was determined to be the optimum pulse frequency for the anodization. Transmission electron microscopy observation and N2 sorption analysis revealed that controlling the minimum pore channel diameter at 3 nm was possible by the voltage of 1 V. The gas permeance according to Knudsen’s diffusion mechanism was demonstrated at 500 °C, by evaluating gas permeation properties through the meso-porous anodic alumina capillary tube with radial meso-pore channels with minimum diameter of 3 nm, achieving hydrogen permeance of 1.8 × 10−6 mol/m2 s Pa.

Highly Ordered Anodic Porous Alumina Formation by Self‐Organized Anodizing

“…A completely novel anodizing technique which employed a pulse sequential voltage with a pulse frequency of 100 Hz was proposed by Inada et al [340]. The technique was used for the strict control of pore diameter in the range of low anodizing potentials (below 3 V) where a linear dependence between pore diameter and forming voltage does not exist.…”

Carbon nanotubes prepared by anodic aluminum oxide template method

“…The smallest pores formed by conventional anodizing have a diameter of ~7 nm [144]. Recently, Inada et al [145] developed a novel anodizing technique which employed a pulse sequential voltage with a frequency of 100 Hz. Low anodizing potentials (below 3 V) were used, and the linear dependence between pore diameter and voltage does not exist in this case.…”

Liquid permeation and chemical stability of anodic alumina membranes

“…AAO membranes are abundantly used as solid porous supports for asymmetric gas separation membranes [6–7] and have been tested in industrial applications as porous condensing layers for on-site associated gas conditioning [8–9]. However, most of AAO membrane functions are associated with gas separation processes [3,5,7–8 10–12], while only few reports can be found for liquid media [1,13–15]. In contrast, the narrow pore size distribution of anodic alumina membranes should result in a sharp cut-off curve and excellent filtration characteristics [1].…”