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Membrane-based gas separation processes are currently being implemented at different scales for several industrial applications. The optimal design of such processes, which is of key importance for their large-scale commercial deployment, has been extensively studied through parametric analyses and optimisation procedures. Nevertheless, the applicability of such design methodologies is generally limited by the large computational time and effort they require. In this work, surrogate models based on artificial neural networks are developed to circumvent the lengthy optimisation of a one-stage and two-stage cascade membrane-based gas separation process. In 200 ms, the surrogate model generates a Pareto front that describes the optimal trade-off between the process specific electricity consumption and productivity based on given input data, i.e., membrane material properties, feed composition and separation target. Whereas the surrogate model is applicable to any binary gas mixture, here its features are illustrated by creating process performance maps for post-combustion CO2 capture. Such maps provide valuable insights on: (i) attainable gas separation regions in term of CO2 recovery and CO2 purity, and (ii) the impact of membrane material, feed composition and separation target on the Pareto fronts and the optimal operating conditions. International Journal of Greenhouse Gas Control, 122 ISSN:1750-5836 ISSN:1878-0148

In hydrogen production, the syngas streams produced by reformers and/or coal gasification plants contain a large amount of H2 and CO in need of upgrading. To this purpose, reactors using Pd-based membranes have been widely studied as they allow separation and recovery of a pure hydrogen stream. However, the high cost of Pd-membranes is one of the main limitations for scaling up technology. Therefore, many researchers are now pursuing the possibility of using supported membranes with as thin as possible Pd-alloy layers. In this work, the upgrading of a syngas stream is experimentally investigated in a water gas shift membrane reactor operated in a high temperature range with an ultra-thin supported membrane (3.6 micron-thick). The membrane permeance was measured before and after catalyst packing and also after reaction for 2100 h of operation in total. Membrane reactor performance was evaluated as a function of operating conditions such as temperature, pressure, gas hourly space velocity, feed molar ratio, and sweep gas. A CO conversion significantly higher than the thermodynamics upper limit of a traditional reactor was achieved, even at high gas hourly space velocities and a 25% less reaction volume than that of a traditional reactor was enough to achieve a 90% equilibrium conversion.

Membrane operations nowadays drive the innovative design of important separation, conversion, and upgrading processes, and contribute to realizing the main principles of “green process engineering” in various sectors. In this perspective, we propose the re-design of traditional plants for biogas upgrading and integrating and/or replacing conventional operations with innovative membrane units. Bio-digester gas streams contain valuable products such as biomethane, volatile organic compounds, and volatile fatty acids, whose recovery has important advantages for environment protection, energy saving, and waste valorization. Advanced membrane units can valorize biogas by separating its various components, and establishing environmentally friendly and small-scale energivorous novel separation processes enables researchers to pursue the requirements of circular economy.

Abstract The recent roadmap of SPIRE initiative includes the development of “new separation, extraction and pre-treatment technologies” as one of the “key actions” for boosting sustainability, enhancing the availability and quality of existing resources. Membrane condenser is an innovative technology that was recently investigated for the recovery of water vapor for waste gaseous streams, such as flue gas, biogas, cooling tower plumes, etc. Recently, it has been also proposed as pre-treatment unit for the reduction and control of contaminants in waste gaseous streams (SOx and NOx, VOCs, H2S, NH3, siloxanes, halides, particulates, organic pollutants). This perspective article reports recent progresses in the applications of the membrane condenser in the treatment of various gaseous streams for water recovery and contaminant control. After an overview of the operating principle, the membranes used, and the main results achieved, the work also proposes the role of this technology as pre-treatment stage to other separation technologies. The potentialities of the technology are also discussed aspiring to pave the way towards the development of an innovative technology where membrane condenser can cover a key role in redesigning the whole upgrading process.