New designs of ceramic hollow fibres toward broadened applications

Abstract

Three structural designs for ceramic membranes have been achieved for the first time through the co-extrusion of polymeric and ceramic layers. During co-extrusion, micro-channels are initiated due to the Rayleigh-Taylor instability and they propagate through the different layers.The polymeric layer(s) is then calcined off during the heat treatment step, which opens the microchannels and following sintering a ceramic membrane with open micro-channels ranging from a few to a few tens of micrometres in diameter can be formed. These long, straight and nontortuous micro-channels can be controlled to be open at any or all of the surfaces. Design 1 has open micro-channels passing through the entire membrane wall, Design 2 has a separation layer at the lumen and open micro-channels at the shell side, and Design 3 has open micro-channels from both lumen and shell sides sandwiching a separation layer of sponge-like structure. Aside from having much improved mass transfer property due to the reduced effective membrane thickness, they can be easily incorporated into hybrid systems with anticipated improvements in unit compactness and performance. The pure water permeation of Design 2 reached up to 159, 000 L/m 2 h bar with pore sizes in the micro-filtration range. The micro-channels are easily accessible from the shell/lumen side; therefore catalysts or adsorbents can be easily deposited into the micro-channels. Examples of possible applications include a high-efficiency dispersing device realised with Design 1; a gas chromatography column for gas separation with very low pressure drop realised with Design 2 and a highly compact membrane micro-reactor for consecutive reactions proposed with Design 3.

Fabrication of Graphene‐Covered Micro‐Tubes for Process Intensification

“…The outer diameter also reduced to 1.8 mm, which can give an area to volume ratio of about 2200 m 2 m −3 at the modular level. The cross‐section of the micro‐tube showed a typical finger‐like structure (Figure c), which was commonly seen in phase‐inversion membranes, and the formation mechanism of such a structure has been intensively discussed in previous studies [10a,12,13]. A more detailed observation at the boundary between the outer and inner layers (Figure d) revealed that the two layers were perfectly sintered together, and it was free of delamination or cracks.…”

Influência do solvente na estrutura de membranas cerâmicas do tipo fibra oca

“…A composição da suspensão cerâmica das fibras produzidas foi de (% em massa): 60% de material cerâmico; 33,6% de solvente (DMSO ou NMP); 0,4% em peso de Arlacel e 6% de PESf. Esta composição foi baseada nos estudos de Lee et al (2016). A extrusão foi realizada utilizando duas bombas seringas (PHD/Ultra HarvardApparatus) conectadas cada uma em uma seringa de aço inoxidável, na qual uma bomba seringa bombeou a suspensão cerâmica na vazão de 15 mL/min e a outra bombeou a água deionizada (coagulante interno) na vazão de 7 mL/min.…”

“…Já com relação ao material da membrana, as membranas cerâmicas apresentam maior resistência térmica, química e mecânica, quando comparadas às poliméricas. A alumina (Al2O3) se trata de um material cerâmico que oferece uma boa combinação entre suas propriedades elétrica e térmica, e que tem sido recomendado na literatura para produção de membranas cerâmicas do tipo fibras ocas utilizando o método de inversão de fases seguido de sinterização Lee et al, 2016). A flexibilidade na combinação dos métodos de inversão de fases e de sinterização permite a produção de estruturas na seção transversal das fibras ocas que podem ser concebidas e adaptadas conforme o desejado, podendo apresentar regiões filamentosas e/ou esponjosas (Lee et al, 2015).…”

Micropatterned Ultrathin MOF Membranes with Enhanced Molecular Sieving Property

“…In this work, we employed lithographic moulding, followed by a phase‐inversion technique,, to prepare patterned porous YSZ substrates. Figure a illustrates how the patterned ceramic substrates were fabricated.…”