Simulation of binary gas separation through multi-tube molecular sieving membranes at high temperatures

Binary gas mixture and hydrothermal stability investigation of cobalt silica membranes

“…It is worthwhile mentioning that a high feed flow rate was used in this work to maintain a relatively constant driving force along the membrane length. This parameter is crucial in generating a steady state condition of the binary gas testing to reduce any concentration gradient along the membrane module [34]. After HT exposure, the membrane showed similar behaviour compared to the as-synthesised membrane, although a slight reduction of He flux was observed.…”

“…For example, a cobalt oxide silica membrane showed a H 2 permeance of 1.8 Â 10 À 7 mol m À 2 s À 1 Pa À 1 with H 2 /N 2 values of $730 at 500°C [31], whilst a niobia silica membrane delivered 3.8 Â 10 À 8 mol m À 2 s À 1 Pa À 1 (H 2 ) and 22 (H 2 /CO 2 ) at 200°C [33]. Single gas permeation is an easy and rapid way to carry out experimental work and to provide fundamental understanding of the performance of membranes, but the results cannot be directly applied to real industrial separation processes due to gas flow effects and changes in driving force [34], and competitive sorption [35] among other reasons. As a consequence, membrane engineers require gas mixture results in order to gain important information on how the membranes would perform in industrial deployment.…”

Temperature dependent transition point of purity versus flux for gas separation in Fe/Co-silica membranes

“…Further, Yacou and co-workers [32] reported that H 2 purity, obtained by gas mixture separation though a large multi-tube membrane module, was not affected by temperature, contrary to the permselectivity for single gases. Recently, Ji et al [33] demonstrated that fluid flow dynamics played a major role in large membrane modules, thus affecting the driving force for gas mixtures and subsequent H 2 fluxes and separation factors. Hence, single gas permeation data may not fulfil the requirements to predict mixed gas permeation and separation, even at high temperature.…”

Zeolite membranes – a review and comparison with MOFs

“…Various models have been proposed in the literature to include its effect by introducing a mass transfer coefficient, 192,201,202 or solving the full concentration profile in the boundary layer. 203,204 The effects can be suppressed by introduction of sweep gas, mixing and making flow turbulent. Another common assumption in modeling zeolite membranes is that they are defect free.…”