Abstract
Ceramic membranes have been considered as potential candidates for several gas separation processes of industrial interest, due to their increased thermal and chemical stability compared to polymeric ones. In the present study, commercial Hybrid Silica (HybSi®) membranes have been evaluated and modified accordingly, to enhance their gas separation performance for targeted applications, including CO2 removal from flue gas and H2 recovery from hydrogen-containing natural gas streams. The developed membranes have been characterized before and after modification by relative permeability, single gas permeation, and equimolar separation tests of the respective gas mixtures. The modification procedures, involving in situ chemical vapor deposition and superficial functionalization, aim for precise control of the membranes’ pore size and surface chemistry. High performance membranes have been successfully developed, presenting an increase in H2/CH4 permselectivity from 12.8 to 45.6 at 250 °C. Ultimately, the modified HybSi® membrane exhibits a promising separation performance at 250 °C, and 5 bar feed pressure, obtaining above 92% H2 purity in the product stream combined with a notable H2 recovery of 65%, which can be further improved if a vacuum is applied on the permeate side, leading to 94.3% H2 purity and 69% H2 recovery.
Highlights
Taking into account that around twothirds of greenhouse gas (GHG) emissions globally come from energy production and consumption activities [1], signifies the need for taking action on energy decarbonization
H2/N2, H2/CH4, and H2/SF6 permselectivities were considerably higher than the corresponding theoretical Knudsen values, while at the same time, the HybSi® membrane seemed to have a strong affinity for CO2, indicated by the significantly Membranes 2022, 12, x FOR PEER REVhIiEgWh CO2/N2 and the low H2/CO2 values
The scope of this work was to evaluate the performance of commercial organic−inorganic hybrid silica (HybSi®) membranes for CO2/N2 and H2/CH4 separations and to investigate whether their efficiency can be enhanced by applying simple post-synthesis Chemical Vapor Deposition (CVD) treatments and adjusting operational parameters, mainly the feed to permeate pressure ratio, Pf/Pp
Summary
The intense concerns about global warming and climate change were stressed again during the recent COP26 conference in Glasgow. Taking into account that around twothirds of greenhouse gas (GHG) emissions globally come from energy production and consumption activities [1], signifies the need for taking action on energy decarbonization. Within this scope, renewable and low-carbon technologies should be broadly deployed so that they end up significantly contributing to the global energy demand. Renewable energy sources such as solar and wind will need to be implemented in abundance in order to meet the global energy demands, they are currently covering only a small share, mainly due to limitations regarding the readiness of energy generation, transportation, and storage infrastructures [2]. Sun and wind do not provide reliable and continuous energy outputs over time, while surplus electricity is often wasted due to limited storage capacities
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