The Separative Performance of Modules with Polymeric Membranes for a Hybrid Adsorptive/Membrane Process of CO2 Capture from Flue Gas

Synthesis and Characterization of Microwave-Assisted Copolymer Membranes of Poly(vinyl alcohol)-g-starch-methacrylate and Their Evaluation for Gas Transport Properties

Poly(vinyl alcohol) (PVA) is an excellent membrane-forming polymer and can be modified with potato starch and methyl acrylate monomers to obtain copolymers with improved physical and chemical properties. The study presents the synthesis of poly(vinyl alcohol)-g-starch-poly(methyl acrylate) PVA-g-St-g-PMA copolymers using microwave irradiation technique and potassium persulfate initiator. Solution casting and solvent evaporation methods were adopted for the fabrication of polyvinyl alcohol-g-starch-acrylamide composite membranes. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal analysis. The modified nanocomposite membranes were showed very promising results with the parameters permeability and selectivity. The nanocomposite membranes exhibited the advantages of easy handling and reuse.

Upgrading Biogas from Small Agricultural Sources into Biomethane by Membrane Separation

The agriculture sector in Poland could provide 7.8 billion m³ of biogas per year, but this potential would be from dispersed plants of a low capacity. In the current study, a membrane process was investigated for the upgrading biogas to biomethane that conforms to the requirements for grid gas in Poland. It was assumed that such a process is based on membranes made from modified polysulfone or polyimide, available in the market in Air Products PRISM PA1020 and UBE UMS-A5 modules, respectively. The case study has served an agricultural biogas plant in southern Poland, which provides the stream of 5 m³ (STP) h⁻¹ of biogas with a composition of CH₄ (52 vol.%), CO₂ (46.3 vol.%), N₂ (1.6 vol.%) and O₂ (0.1 vol.%), after a pretreatment. It was theoretically shown that this is possible to obtain the biomethane stream of at least 96 vol.% of CH₄ purity, with the concentration of the other biogas components below their respective thresholds, as required in Poland for gas fuel “E”, with methane recovery of up to 87.5% and 71.6% for polyimide and polysulfone membranes, respectively. The energetic efficiency of the separation process is comparable for both membrane materials, as expressed by power excess index, which reaches up to 51.3 kW_th kW_el⁻¹ (polyimide) and 40.7 kW_th kW_el⁻¹ (polysulfone). In turn, the membrane productivity was significantly higher in the case of the polyimide membrane (up to 38.3 kW_th m⁻²) than those based on the polysulfone one (up to 3.13 kW_th m⁻²).

A comparative review of potential ammonia-based carbon capture systems

Carbon capturing technologies are recognized as a cornerstone solution in reducing greenhouse gas emissions to meet the 2050 emissions targets set during the past Paris agreement. Recently, ammonia has become a major carbon-free chemical to absorb CO₂ emissions from flue gases. In this regard, this paper concerns the recently developed novel ammonia-based carbon capturing systems in the open literature and comparatively evaluates them from various perspectives in addition to discussing their advantages and disadvantages. The systems considered are basically classified into three categories, namely renewable energy-based systems, energy savings-focused systems, and Integrated Gasification Combined Cycle (IGCC)-based systems. Then, comparative assessments of the novel systems are conducted to see their advantages and weaknesses as compared to the typical chilled ammonia process. Generally, the novel systems have significantly lower energy requirements. The highest reduction is 37.3%. Another result of the comparative study is that renewable energy-based systems of carbon capturing have higher operational costs that can reach up to C$136 ton^-1 of CO₂ captured. Future efforts are expected to focus on reducing these costs since renewable energy-based systems are also used to co-produce chemical commodities, such as urea and ammonium bicarbonate. These high-value commodities have the potential to generate enough economic value to compensate for the operational costs of carbon capturing using ammonia as a chemical solvent.