Preparation and analysis of high capacity polysulfone capsules

Since the concept of solvent impregnated resins was introduced in the early 1980s, the technique has been applied to a limited amount of applications. The main disadvantage of the resins was that the amount of solvent inside was limited to approximately 1.5 ml/g polymer. A new generation of solvent impregnated resins is introduced. These capsules can contain up to 11.8 ml solvent/g polymer and were prepared using a modified dry impregnation technique. Due to the high solvent loading, the capacity per volume of capsule for extracting products from aqueous phases is therefore dramatically increased.     

Solvent impregnated resins for the removal of low concentration phenol from water

The focus of this investigation is the development of a solvent impregnated resin for phenol removal from dilute aqueous solutions. Using a solvent impregnated resin (SIR) eliminates the problem of emulsification encountered in liquid–liquid extraction. Impregnated MPP particles and impregnated XAD16 particles are successfully used for phenol extraction. Impregnated MPP particles are preferred, as impregnated XAD16 particles show less mechanical strength and are more expensive. Impregnated MPP particles perform better compared to other synthetic adsorbents and basic ion exchangers. The maximum phenol capacity of impregnated MPP particles with 0.99 mol Cyanex 923 kg⁻¹ SIR is 4.1 mol kg⁻¹ SIR (386 mg g⁻¹ SIR) and of MPP particles containing 1.47 mol Cyanex 923 kg⁻¹ SIR it is 5.08 mol kg⁻¹ SIR (478 mg g⁻¹ SIR). The regenerability of impregnated MPP particles is easy and complete, and the particles are stable during several cycles. The equilibrium constants for the extraction of phenol are determined as K_chem = 37 L mol⁻¹ and K_phys = 18 (mol L⁻¹) (mol L⁻¹)⁻¹. With these values the SIR isotherms can be satisfactorily described.The results indicate that SIR technology is a promising alternative for the conventional phenol removal technologies at low phenol concentration levels.     

New process concepts for CO2 post-combustion capture process integrated with co-production of hydrogen

This work describes a study in advanced post-combustion based on CO₂-capture technologies to be integrated within the Hypogyny concept (electricity generation with co-hydrogen production). Two different Hypogen concepts based on integrating IGCC (Integrated Gasification Combined Cycle) and post-combusting CO₂ capture are proposed and investigated: the first concept, hydrogen production based on syngas shifting with high-pressure CO₂ capture, while the second concept, hydrogen is produced based on membrane separation from syngas.In the first concept, combining a high-pressure and an ambient-pressure CO₂ absorber in one flow sheet and one regeneration column is found to be feasible. However, the advantage of the high CO₂ partial pressure in the high-pressure absorber is more obvious if an advanced solvent like 2-amino-2-methyl-1-propanol (AMP) is used instead of monoethanolamine (MEA) solvent kind.The second concept of using polymeric membrane for hydrogen production is considered feasible and comparing to the first concept, cost competitive with around 10% higher overall capital cost. However, the membrane unit does not achieve high hydrogen purity because the investigated concept is limited to a maximum purity of around 95%. Therefore, hydrogen selective membrane technically requires an extra hydrogen purification step e.g. further membrane separations or a pressure swing adsorption (PSA).In addition to these two concepts, the influence of flue gas circulation, gasifier selection and an advanced solvent based on the sterically hindered amine AMP was investigated. Flue gas circulation (higher CO₂-concentrations) has no influence on the regeneration energy requirements when a high binding-energy solvent like MEA is used. The main benefit is that flue gas circulation results with more compact absorption equipment. For AMP type of solvents flue gas circulation results in a substantial reduction in regeneration energy and the overall cost of CO₂ avoided. 37% reduction in the avoided cost with a flue gas recycle ratio of 45% is achieved using AMP as a solvent comparing to 10% using MEA solvent.These Hypogen strategies appear to be feasible and the overall cost of these concepts is comparable with the conventional post-combustion capture process. However, there is a significant potential for further improvement by applying more developed solvents, processes, and membranes.     

Kinetics of carbon dioxide removal from water in flat membrane contactor

The problem of regeneration of a carbon dioxide physical absorbent in gas-liquid membrane contactor has been addressed using water as the absorbent. An analytical solution for the mass transfer equation has been obtained with taking into account not only axial, but also radial diffusion of the solute in the liquid flow and thereby significantly extending the area of applicability of the solution. The kinetics of carbon dioxide desorption from aqueous solutions has been described for the membrane contactor based on asymmetric gas separation membrane made of polyvinyltrimethylsilane (PVTMS). It has been shown that the model agrees well with experimental data for different pressures of water saturation with carbon dioxide and desorption temperatures.     

Methane pyrolysis in a molten gallium bubble column reactor for sustainable hydrogen production: Proof of concept & techno-economic assessment

Nowadays, nearly 50% of the hydrogen produced worldwide comes from Steam Methane Reforming (SMR) at an environmental burden of 10.5 t_CO2,eq/t_H2, accelerating the consequences of global warming. One way to produce clean hydrogen is via methane pyrolysis using melts of metals and salts. Compared to SMR, significant less CO₂ is produced due to conversion of methane into hydrogen and carbon, making this route more sustainable to generate hydrogen. Hydrogen is produced with high purity, and solid carbon is segregated and deposited on the molten bath. Carbon may be sold as valuable co-product, making industrial scale promising. In this work, methane pyrolysis was performed in a quartz bubble column using molten gallium as heat transfer agent and catalyst. A maximum conversion of 91% was achieved at 1119 °C and ambient pressure, with a residence time of the bubbles in the liquid of 0.5 s. Based on in-depth analysis of the carbon, it can be characterized as carbon black. Techno-economic and sensitivity analyses of the industrial concept were done for different scenarios. The results showed that, if co-product carbon is saleable and a CO₂ tax of 50 euro per tonne is imposed to the processes, the molten metal technology can be competitive with SMR.     

Thermo pervap: The next step in energy efficient pervaporation

Thermo pervaporation (PV) is a pervaporation process that makes use of low quality heat to recover or purify solvents from water. Based on this technology it is possible to integrate the condensation energy for the direct heating of the feed during pervaporation in one single module.This concept was experimentally investigated for the separation of ethanol from a mixture of ethanol-water. It was possible to obtain a heat recovery of 33% (meaning that 33% of the heat transferred to the feed stream is condensation heat) and fluxes up to 0.5 kg/m² h at high ethanol concentration.