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The Pd-based double-skin (DS) membrane has high potential to be implemented in various industrial processes. However, its multi-layer structure makes it difficult to model and understand the limiting transport mechanisms through each of these layers. In this work an extensive set of experiments on several membranes with different configurations was performed with the purpose of deriving a detailed model for the double-skin Pd-based membrane. This is important for the general understanding of the mass-transport taking place within each of the membrane layers, namely the support, the selective and the protective layer. Characterization, permeation tests and data-fitting led to the construction and validation of a multi-layer model for the DS-membrane. The experimental results also pointed out that the protective layer of HT or YSZ/Al2O3 has only a minor or negligible effect on the overall transport resistance of the membrane. The influence of the support was found to be small but not negligible compared to the dominating resistance of the dense selective PdAg layer. Experiments and simulations of the membrane permeation in multi-component mixtures also highlighted the large importance of concentration polarization and H2 depletion, which were successfully described in the model using a film-layer model together with a Sherwood correlation.

As respiratory syncytial virus (RSV) vaccine distribution gains traction in Europe and Italy, healthcare workers (HCWs) can strategize about vaccine promotion to increase uptake among patients at risk of RSV consequences, such cardiac patients. This cross-sectional survey investigated the knowledge about and attitude towards RSV and RSV vaccines, and the intention to recommend vaccination within a cardiological hospital in Italy. To explore factors associated with the outcomes of interest, multivariate logistic regression analyses were conducted. Of 197 invited HCWs, 78.2% returned the survey. The knowledge about market authorisation for new RSV vaccines for older adults (present in 46.9% of respondents) was significantly associated with the HCWs’ age, education, and previous update on vaccinations. HCWs with a higher educational level and those with a positive attitude towards RSV vaccines safety reported a higher attitude towards the importance of vaccinating people at risk. The willingness of recommending RSV vaccination to patients (70.5% of respondents) was more likely in HCWs who were knowledgeable about market authorisation for RSV vaccines and in physicians. This tempestive research sheds light on current factors influencing the strategies of cardiac HCWs regarding RSV vaccination. The results suggest the need for training events on the protective role of RSV vaccination in cardiac patients.

The energy efficiency of two novel process designs for the production of ultra-pure hydrogen with simultaneous capture of CO2 using CH4 as the feedstock, namely membrane-assisted chemical looping reforming (MA-CLR) and membrane-assisted sorption-enhanced reforming (MA-SER) has been compared. The modelling of the integrated network for mass and heat balances has been carried out using the ASPEN® Plus V10 process simulation tool to quantify the benefits and disadvantages of integrating hydrogen perm-selective membranes with either chemical looping or sorption-enhanced reforming. The evaluation of the MA-CLR process is carried out for a range of the following operating conditions: 10 < pR < 60 bar, 500 < TR < 900°C, and 1.5 < H2O/CH4 < 3.0. On the other hand, for the MA-SER process the operation ranges of 1.0 < pR < 10 bar, 400 < TR < 900°C, and 2.5 < H2O/CH4 < 4.0 were considered. Within the operation window of the MA-SER process, no carbon formation is observed, as any carbon present in the system reacts with CaO in the form of CO2. However, in the case of the MA-CLR process, carbon formation can occur during the pre-reforming stage, particularly at low H2O/CH4 ratios. In terms of hydrogen yield, energy utilization and carbon capture, the MA-CLR outperforms the MA-SER plant. However, the MA-SER plant offers certain advantages over the MA-CLR system, such as a pure CO2 product stream and lower reactor design temperatures. In the MA-CLR system, a carbon capture rate of 99.8% and a hydrogen product yield of 74.4% are achieved, whereas the MA-SER plant achieves a carbon capture rate of 98.5% and a hydrogen product yield of 69.7%.

The applicability of PdAg membranes in the propane dehydrogenation process has been evaluated in this work. The integration of membranes into the propane dehydrogenation process has the potential of making a significant step forward in energy and resource efficiency of the selective production of propylene. To assess the compatibility of the PdAg membrane with the process conditions of propane dehydrogenation, two double-skin PdAg membranes were exposed to the emulated process conditions of two cases: 1. A fully integrated membrane-reactor system (higher temperature) and 2. A cascade of catalyst and membrane separator units (lower temperature). The results of this study showed that at high temperature (475–500 °C) strong reduction of the hydrogen flux is observed during exposure to reactant and product containing mixtures. The reason for this is the deposition of carbonaceous species on the active sites of the membrane. Additionally, also the lifetime of the membrane (in terms of selectivity) was significantly lower due to the regeneration performed at high temperature in diluted air. The lower temperature experiments (300–350 °C) showed a much lower degree of deactivation and at the same time the membrane could be regenerated in air repeatedly without visible reduction of its selectivity. These findings show that the DS-PdAg membrane can be repeatedly exposed to reaction-regeneration cycles at acceptable activity and without significant loss of selectivity when operated in a cascade configuration at a temperature at or below 350 °C.

Sustainable aviation fuel (SAF) production from captured carbon dioxide and green hydrogen, is referred to as the key to decarbonize the hard-to-abate aviation sector. Fischer-Tropsch is a mature and reliable pathway for hydrocarbon synthesis, with a wide spectrum of technological options and high plant efficiency extending to more than 80 % of e-kerosene selectivity. In this work, an Aspen Hysys model, coupled with different Matlab simulations for Fischer-Tropsch, Hydrocracker and SOEC, was set up to estimate efficiency and selectivity. The results show that global efficiency is mainly linked to the efficiency of the production of H2. Energetic efficiency reaches 48.06 % using the already existing commercial electrolyte supported cell in a SOEC electrolyser, but it could increase to 65.74 % if cathode supported cell was considered.

The use of Carbon Molecular Sieve Membranes (CMSM) for selective CO2 separation from post-combustion CO2-rich streams from steel plant was experimentally evaluated and reported in this paper. Efficient CMSMs were developed for such application and their promising potentials in operating at elevated temperatures and pressures were experimentally demonstrated. The best performance in terms of flux as well as perm-selectivity, above the Robeson upper bound, was obtained using a CMSM developed with ethylenediamine in the dip-coating stage of the fabrication. In fact, adding ethylenediamine was proven to be particularly important in narrowing down the pore size distribution to ultra-micropore and establishing effective CO2 adsorption site over the membrane surface and the pores wall. It was shown that using a tailored CMSM with a precursor synthesized by co-polymerization of ethylenediamine with Novolac can improve the CO2/N2 ideal perm-selectivity from 33 to 97 at operational conditions of 200 °C and 20 bar.

Background: The burden of cardiovascular (CV) complications in patients hospitalised for community-acquired pneumonia (CAP) is still uncertain. Available studies used different designs and different criteria to define CV complications. We assessed the cumulative incidence of acute of CV complications during hospitalisation for CAP in Internal Medicine Units (IMUs). Methods: This was a prospective study carried out in 26 IMUs, enrolling patients consecutively hospitalised for CAP. Defined CV complications were: newly diagnosed heart failure, acute coronary syndrome, new onset of supraventricular or ventricular arrhythmias, new onset hemorrhagic or ischemic stroke or transient ischemic attack. Outcome measures were: in-hospital and 30-day mortality, length of hospital stay and rate of 30-day re-hospitalisation. Results: A total of 1266 patients were enrolled, of these 23.8% experienced at least a CV event, the majority (15.5%) represented by newly diagnosed decompensated heart failure, and 75% occurring within 3 days. Female gender, a history of CV disease, and more severe pneumonia were predictors of CV events. In-hospital (12.2% vs 4.7%, p < 0.0001) and 30-day (16.3% vs 8.9%, p = 0.0001) mortality was higher in patients with CV events, as well as the re-hospitalisation rate (13.3% vs 9.3%, p = 0.002), and mean hospital stay was 11.4 ± 6.9 vs 9.5 ± 5.6 days (p < 0.0001). The occurrence of CV events during hospitalisation significantly increased the risk of 30-day mortality (HR 1.69, 95% CI 1.14–2.51; p = 0.009). Conclusion: Cardiovascular events are frequent in CAP, and their occurrence adversely affects outcome. A strict monitoring might be useful to intercept in-hospital CV complications for those patients with higher risk profile. Trial registration: NCT03798457 Registered 10 January 2019 - Retrospectively registered

With a growing interest in hydrogen as energy carrier, the efficient purification of hydrogen from gaseous mixtures is very important. This paper addresses the separation of hydrogen using Carbon Molecular Sieves Membranes (CMSM), which show an attractive combination of high permeability, selectivity and stability. Supported CMSM containing various amounts of aluminium have been prepared from novolac and aluminium acetyl acetonate (Al(acac)3) as carbon and alumina precursors. The thickness of the CMSM layers depend on the content of Al(acac)3 in the dipping solution, which also has influence in the pore size and pore size distribution of the membranes. The permeation properties of the membranes against the Al content in the membrane follows a volcano shape, where the membrane containing 4 wt (%) of Al(acac)3 has the best properties and was stable during 720 h for hydrogen at 150 °C and 6 bar pressure difference. All the CMSM have permeation properties well above the Robeson Upper limit.

Tubular supported carbon molecular sieve membranes (CMSMs) with high hydrophilicity and perm-selectivities for water suitable for ethanol dehydration were developed from a Novolac oligomer phenolic resin as precursor. Alpha alumina supported CMSMs resulted in 1.69 times higher surface roughness than zirconia supports. The higher surface roughness resulted in 48% higher selective layer thickness. According to pervaporation results, water permeance decreased by the increase in selective layer thickness and mole based selectivity of water- ethanol was enhanced. The oligomer with 3982 g/mol molecular weight enabled membrane to reach high selectivity with one-layer coating. Performance of the membranes are compared with literature data in terms of mole-based selectivity vs. water permeance. CMSMs could be a potential substitution for traditional ethanol dehydration methods with offering higher performance and as a result reducing the final price of bioethanol to be used as a sustainable energy source.

In this work, a novel Pd–Ag double-skinned (DS-) membrane is used for the first time in conditions typical of propane dehydrogenation (PDH). This membrane presents a protective layer on top of the H2-selective one, which acts as shield against chemical deactivation and mechanical erosion under reaction conditions. While the protective layer is already been proven as an efficient barrier against membrane erosion in fluidized beds, there is no validation yet under PDH reaction. The DS- membrane performance is compared with a conventional (C-) Pd–Ag membrane under alkane/alkene exposure, at 400–500 °C and 3 bar, to investigate whether the incorporation of the protective layer would be suited for H2 separation in PDH systems, and if coking rate would be affected. The novel membrane shows a H2 permeance of 2.28 × 10−6 mol∙m−2 s−1∙Pa−1 at 500 ᵒC and 4 bar of pressure difference, overcoming the performance of the conventional PdAg one (1.56x∙10−6 mol m−2 s−1∙Pa−1). Both membranes present a stable H2 flux under alkane exposure, while deactivation occurs under exposure to alkenes. A model able to describe the H2 flux through Pd-based membranes is presented to fit the experimental data and predict membrane performance. The model includes mass transfer limitations in the retentate and a corrective inhibition factor to account for the competitive adsorption of hydrocarbon species in the H2 selective layer. The experimental results obtained under alkene exposure deviates from model predictions; this can be attributed to carbon deposition on the surface of the selective layer, as further detected on the DS-membrane by Scanning Electron Microscopy (SEM)/Energy Dispersive X-Ray Analysis (EDX), which is the main factor for membrane deactivation.

With a growing interest in hydrogen as energy carrier, the efficient purification of hydrogen from gaseous mixtures is very important. This paper addresses the separation of hydrogen using Carbon Molecular Sieves Membranes (CMSM), which show an attractive combination of high permeability, selectivity and stability. Supported CMSM containing various amounts of aluminium have been prepared from novolac and aluminium acetyl acetonate (Al(acac)3) as carbon and alumina precursors. The thickness of the CMSM layers depend on the content of Al(acac)3 in the dipping solution, which also has influence in the pore size and pore size distribution of the membranes. The permeation properties of the membranes against the Al content in the membrane follows a volcano shape, where the membrane containing 4 wt (%) of Al(acac)3 has the best properties and was stable during 720 h for hydrogen at 150 °C and 6 bar pressure difference. All the CMSM have permeation properties well above the Robeson Upper limit.

In this work, a novel Pd–Ag double-skinned (DS-) membrane is used for the first time in conditions typical of propane dehydrogenation (PDH). This membrane presents a protective layer on top of the H2-selective one, which acts as shield against chemical deactivation and mechanical erosion under reaction conditions. While the protective layer is already been proven as an efficient barrier against membrane erosion in fluidized beds, there is no validation yet under PDH reaction. The DS- membrane performance is compared with a conventional (C-) Pd–Ag membrane under alkane/alkene exposure, at 400–500 °C and 3 bar, to investigate whether the incorporation of the protective layer would be suited for H2 separation in PDH systems, and if coking rate would be affected. The novel membrane shows a H2 permeance of 2.28 × 10−6 mol∙m−2 s−1∙Pa−1 at 500 ᵒC and 4 bar of pressure difference, overcoming the performance of the conventional PdAg one (1.56x∙10−6 mol m−2 s−1∙Pa−1). Both membranes present a stable H2 flux under alkane exposure, while deactivation occurs under exposure to alkenes. A model able to describe the H2 flux through Pd-based membranes is presented to fit the experimental data and predict membrane performance. The model includes mass transfer limitations in the retentate and a corrective inhibition factor to account for the competitive adsorption of hydrocarbon species in the H2 selective layer. The experimental results obtained under alkene exposure deviates from model predictions; this can be attributed to carbon deposition on the surface of the selective layer, as further detected on the DS-membrane by Scanning Electron Microscopy (SEM)/Energy Dispersive X-Ray Analysis (EDX), which is the main factor for membrane deactivation.

Tubular supported carbon molecular sieve membranes (CMSMs) with high hydrophilicity and perm-selectivities for water suitable for ethanol dehydration were developed from a Novolac oligomer phenolic resin as precursor. Alpha alumina supported CMSMs resulted in 1.69 times higher surface roughness than zirconia supports. The higher surface roughness resulted in 48% higher selective layer thickness. According to pervaporation results, water permeance decreased by the increase in selective layer thickness and mole based selectivity of water- ethanol was enhanced. The oligomer with 3982 g/mol molecular weight enabled membrane to reach high selectivity with one-layer coating. Performance of the membranes are compared with literature data in terms of mole-based selectivity vs. water permeance. CMSMs could be a potential substitution for traditional ethanol dehydration methods with offering higher performance and as a result reducing the final price of bioethanol to be used as a sustainable energy source.

In this work an experimental proof-of-concept of the Ca-Cu process has been carried out. The Ca-Cu process combines sorption-enhanced steam reforming of methane with a Ca-based sorbent with chemical looping of a Cu-based oxygen carrier to provide the energy for the sorbent regeneration. Each process step has been studied separately for different operating pressures and inlet gas compositions, and addition complete cycles (including all three consecutive process steps, viz. the sorption-enhanced reforming step, oxidation step and regeneration step) have been performed to evaluate the technical feasibility of the complete process. The pressure influences the sorption-enhanced reforming step negatively, while the steam-to-carbon ratio does not influence the average outlet H2 (dry) fraction. When increasing the inlet O2 concentration during the oxidation step, the amount of CO2 released increases, whereas increasing the pressure decreases the amount of CO2 released. In the regeneration step, increasing the H2 fraction in the feed increases the amount of sorbent that is regenerated, reaching 70 wt% of the sorbent in the bed with 60 vol% H2 in the feed. More than 285 complete cycles were performed, the solids were still chemically performing well, and the results were still reproducible. Simulations with a pseudo-homogeneous reactor model were performed for all the separate steps. The model does not describe the experimental data well, which was attributed to problems with the packing of the bed at the bottom of the reactor (solids maldistribution), which was confirmed after opening the reactor after the experimental campaign. The problems with the packing of the bed was caused by problems with the chemical–mechanical stability of the oxygen carrier, which became a powder after the experiments due to the high mechanical stresses it was exposed to.

In this work an experimental proof-of-concept of the Ca-Cu process has been carried out. The Ca-Cu process combines sorption-enhanced steam reforming of methane with a Ca-based sorbent with chemical looping of a Cu-based oxygen carrier to provide the energy for the sorbent regeneration. Each process step has been studied separately for different operating pressures and inlet gas compositions, and addition complete cycles (including all three consecutive process steps, viz. the sorption-enhanced reforming step, oxidation step and regeneration step) have been performed to evaluate the technical feasibility of the complete process. The pressure influences the sorption-enhanced reforming step negatively, while the steam-to-carbon ratio does not influence the average outlet H2 (dry) fraction. When increasing the inlet O2 concentration during the oxidation step, the amount of CO2 released increases, whereas increasing the pressure decreases the amount of CO2 released. In the regeneration step, increasing the H2 fraction in the feed increases the amount of sorbent that is regenerated, reaching 70 wt% of the sorbent in the bed with 60 vol% H2 in the feed. More than 285 complete cycles were performed, the solids were still chemically performing well, and the results were still reproducible. Simulations with a pseudo-homogeneous reactor model were performed for all the separate steps. The model does not describe the experimental data well, which was attributed to problems with the packing of the bed at the bottom of the reactor (solids maldistribution), which was confirmed after opening the reactor after the experimental campaign. The problems with the packing of the bed was caused by problems with the chemical–mechanical stability of the oxygen carrier, which became a powder after the experiments due to the high mechanical stresses it was exposed to.

Biogas plants are a widespread renewable energy technology. However, the use of digestate for agronomic purposes has often been a matter of concern. It is controversial whether biogas plants might harbor some pathogenic clostridial species, which represent a biological risk. Moreover, the inhabitance of Clostridium hard-cheese spoiling species in anaerobic digesters can be problematic for hard-cheese manufacturing industries, due to the issue of cheese blowing defects. This study investigated the effect of mesophilic anaerobic digestion processes on the Clostridium consortia distribution over time. Specifically, three lab-scale CSTRs treating agricultural biomass were characterized by considering both the whole microbial community and the cultivable clostridial spores. It is assessed an overall reduction of the Clostridium genus during the anaerobic digestion process. Moreover, it was evidenced a slight, but steady decrease of the cultivable clostridial spores, mainly represented by two pathogenic species, C. perfringens and C. bifermentans, and one hard-cheese spoiling species, C. butyricum. Thus, it is revealed an overall reduction of the clostridial population abundance after the mesophilic anaerobic digestion treatment of agricultural biomass.

A techno-economic analysis of a natural gas combined cycle integrated with a pre-combustion CO2 capture process based on the Ca-Cu process has been carried out. An extensive calculation of the balances of the entire power plant has been done, including the results obtained from a 1-D pseudo homogeneous model for the fixed bed reactors that compose the Ca-Cu process. Moreover, a methodology developed by the authors is here presented for calculating the cost of the electricity produced and of the CO2 avoided. This methodology has been used to perform the economic analysis of the Ca-Cu based power plant and to optimize the size of the Ca-Cu reactors and the pressure drop in critical heat exchangers. An electricity cost of 82.6 €/MWh has been obtained for the Ca-Cu based power plant, which is 2.2 €/MWh below the benchmark power plant based on an Auto Thermal Reformer with an MDEA absorption process for CO2 capture. The improved performance of the Ca-Cu based power plant in terms of electric efficiency and reduced capital cost expenditure is the reason for the reduced electricity costs. Moreover, a lower cost of CO2 avoided is also obtained for the Ca-Cu plant with respect to the benchmark (80.75 €/tCO2 vs. 85.38 €/tCO2), which features 89% of CO2 capture efficiency.

Membrane reactor processes are being increasingly proposed as an attractive solution for pure hydrogen production due to the possibility to integrate production and separation inside a single reactor vessel. High hydrogen purity can be obtained through dense metallic membranes, especially palladium and its alloys, which are highly selective to hydrogen. The use of thin membranes seems to be a good industrial solution in order to increase the hydrogen flux while reducing the cost of materials. Typically, the diffusion through the membrane layer is the rate-limiting step and the hydrogen permeation through the membrane can be described by the Sieverts’ law but, when the membrane becomes thinner, the diffusion through the membrane bulk becomes less determinant and other mass transfer limitations might limit the permeation rate. Another way to increase the hydrogen flux at a given feed pressure, is to increase the driving force of the process by feeding a sweep gas in the permeate side. This effect can however be significantly reduced if mass transfer limitations in the permeate side exist. The aim of this work is to study the mass transfer limitation that occurs in the permeate side in presence of sweep gas. A complete model for the hydrogen permeation through Pd–Ag membranes has been developed, adding the effects of concentration polarization in retentate and permeate side and the presence of the porous support using the dusty gas model equation, which combines Knudsen diffusion, viscous flow and binary diffusion. By studying the influence of the sweep gas it has been observed that the reduction of the driving force is due to the stagnant sweep gas in the support pores while the concentration polarization in the permeate is negligible.

A techno-economic analysis of a natural gas combined cycle integrated with a pre-combustion CO2 capture process based on the Ca-Cu process has been carried out. An extensive calculation of the balances of the entire power plant has been done, including the results obtained from a 1-D pseudo homogeneous model for the fixed bed reactors that compose the Ca-Cu process. Moreover, a methodology developed by the authors is here presented for calculating the cost of the electricity produced and of the CO2 avoided. This methodology has been used to perform the economic analysis of the Ca-Cu based power plant and to optimize the size of the Ca-Cu reactors and the pressure drop in critical heat exchangers. An electricity cost of 82.6 €/MWh has been obtained for the Ca-Cu based power plant, which is 2.2 €/MWh below the benchmark power plant based on an Auto Thermal Reformer with an MDEA absorption process for CO2 capture. The improved performance of the Ca-Cu based power plant in terms of electric efficiency and reduced capital cost expenditure is the reason for the reduced electricity costs. Moreover, a lower cost of CO2 avoided is also obtained for the Ca-Cu plant with respect to the benchmark (80.75 €/tCO2 vs. 85.38 €/tCO2), which features 89% of CO2 capture efficiency.

Membrane reactor processes are being increasingly proposed as an attractive solution for pure hydrogen production due to the possibility to integrate production and separation inside a single reactor vessel. High hydrogen purity can be obtained through dense metallic membranes, especially palladium and its alloys, which are highly selective to hydrogen. The use of thin membranes seems to be a good industrial solution in order to increase the hydrogen flux while reducing the cost of materials. Typically, the diffusion through the membrane layer is the rate-limiting step and the hydrogen permeation through the membrane can be described by the Sieverts’ law but, when the membrane becomes thinner, the diffusion through the membrane bulk becomes less determinant and other mass transfer limitations might limit the permeation rate. Another way to increase the hydrogen flux at a given feed pressure, is to increase the driving force of the process by feeding a sweep gas in the permeate side. This effect can however be significantly reduced if mass transfer limitations in the permeate side exist. The aim of this work is to study the mass transfer limitation that occurs in the permeate side in presence of sweep gas. A complete model for the hydrogen permeation through Pd–Ag membranes has been developed, adding the effects of concentration polarization in retentate and permeate side and the presence of the porous support using the dusty gas model equation, which combines Knudsen diffusion, viscous flow and binary diffusion. By studying the influence of the sweep gas it has been observed that the reduction of the driving force is due to the stagnant sweep gas in the support pores while the concentration polarization in the permeate is negligible.

Hand-foot syndrome (HFS) is a common skin toxicity of traditional chemotherapies. Some studies showed that HFS has an association with progression-free survival (PFS) and the overall survival (OS). So far, there is not available any systematic literature reviews or meta-analysis aimed to assess the associations between HFS, PFS and OS. For this reason, this study aims to quantitatively summarize, critically review, and interpret the recent literature related to the associations between HFS and efficacy of chemotherapy in terms of PFS and OS. Queries shaped by PICOM framework, a systematic search of three electronic databases (PubMed, Scopus, and Science Direct) was carried out for the period between January 2010 and December 2017. Quantitative data pooling was based on the calculation of Hazard Ratio (HR) with 95% Confidence Interval (95% CI) for the OS and PFS associated to the presence of HFS, through the data of original publications. Five papers were included in this systematic review for the quantitative data pooling. Patients with HFS showed improved PFS (HR = 0.532 [0.431-0.656]; p = 0.000) and improved OS (HR = 0.522 [0.427-0.638]; p = 0.000). HFS causes a reduction of compliance with oncology treatments. Healthcare providers should use this result as a trigger to foster patients' coping and the one of their family caregivers, enhancing their adherence to cancer treatments.

Introduction The biological process of anaerobic digestion cannot totally prevent the recontamination and regrowth of pathogenic bacteria. The presence of some clostridial species could also be controversial for the hard-cheese manufacturing industries, which also utilize biogas plants for energy recovery. Indeed, some species of Clostridium (i.e., C. tyrobutyricum, C. butyricum, C. sporogenes) are known to be responsible for the blowing defects of hard cheeses. Since Clostridium spp. are known to be among the main players during the hydrolytic and acidogenic phases of anaerobic digestion, it is important to assess whether the presence of some clostridial species in the digestate of biogas plants could be problematic in terms of biological risk for both agronomic purposes and food industry processes. The aim of this study was to investigate the effect of the anaerobic digestion process on the Clostridium consortia distribution.

A comprehensive kinetic model was developed for the description of the sorption behavior of CO2, H2O and their interactions on potassium-promoted hydrotalcite-based sorbents. An Elovich-type equation has been used to describe the interactions of gas molecules with heterogeneous surface sites on the sorbent, accounting for the change in activation energy of desorption as a function of the surface coverage. The ability of the sorbent to desorb more CO2 while adsorbing H2O and vice versa was modeled with an additional adsorption site, assuming equimolar exchange between CO2 and H2O. A Freundlich isotherm was used to describe the change in adsorption capacity of CO2 and H2O as a function of the partial pressure of CO2 and H2O respectively, while the sorption capacity of the exchange site depends on both the CO2 and H2O partial pressures and could be described with a Freundlich type dependency for both CO2 and H2O. A good description of the desorption kinetics of both CO2 and H2O measured by extensive thermogravimetric analysis experiments has been obtained. The model is shown to adequately describe the complex sorption behavior at various experimental conditions between 300 and 500 °C and different partial pressures of the sorbate species CO2 and H2O and their mixtures. This is the first time that a kinetic model has been developed that can describe the adsorption and desorption kinetics of both CO2 and H2O including their complex interactions.

This work reports the integration of thin (∼3–4 μm thick) Pd-based membranes for H2 separation in a fluidized bed catalytic reactor for ethanol auto-thermal reforming. The performance of a fluidized bed membrane reactor has been investigated from an experimental and numerical point of view. The demonstration of the technology has been carried out over 50 h under reactive conditions using 5 thin Pd-based alumina-supported membranes and a 3 wt%Pt-10 wt%Ni catalyst deposited on a mixed CeO2/SiO2 support. The results have confirmed the feasibility of the concept, in particular the capacity to reach a hydrogen recovery factor up to 70%, while the operation at different fluidization regimes, oxygen-to-ethanol and steam-to-ethanol ratios, feed pressures and reactor temperatures have been studied. The most critical part of the system is the sealing of the membranes, where most of the gas leakage was detected. A fluidized bed membrane reactor model for ethanol reforming has been developed and validated with the obtained experimental results. The model has been subsequently used to design a small reactor unit for domestic use, showing that 0.45 m2 membrane area is needed to produce the amount of H2 required for a 5 kWe PEM fuel-cell based micro-CHP system.

Pd-Ag supported membranes have been prepared by coating a ceramic interdiffusion barrier onto a Hastelloy X (0.2 µm media grade) porous support followed by deposition of the hydrogen selective Pd-Ag (4–5 µm) layer by electroless plating. To one of the membranes an additional porous Al2O3-YSZ layer (protective layer with 50 wt% of YSZ) was deposited by dip-coating followed by calcination at 550 °C on top of the Pd-Ag layer, and this membrane is referred to as a double-skin membrane. Both membranes were integrated at the same time in a single reactor in order to assess and compare the performance of both membranes under identical conditions. The membranes have first been tested in an empty reactor with pure gases (H2 and N2) and afterwards in the presence of a catalyst (rhodium onto promoted alumina) fluidized in the bubbling regime. The membranes immersed in the bubbling bed were tested at 400 °C and 500 °C for 115 and 500 h, respectively. The effect of the protective layer on the permeation properties and stability of the membranes were studied. The double-skinned membraned showed a H2 permeance of 1.55·10−6 mol m−2 s−1 Pa−1 at 500 °C and 4 bar of pressure difference with an ideal perm-selectivity virtually infinite before incorporation of particles. This selectivity did not decay during the long term test under fluidization with catalyst particles.

For the first time, 12 different supported deep eutectic solvent (DES) liquid membranes were prepared and characterized. These membranes consist of a polymeric support impregnated with a hydrophobic DES. First, the different membranes were characterized and their stability in water and air was determined. Subsequently, the supported DES liquid membranes were applied for the recovery of furfural (FF) and hydroxymethylfurfural (HMF) from aqueous solutions. The effects of substrate properties (e.g. pore size), DES properties (e.g. viscosity) and concentrations of FF and HMF in the feed phase on the observed diffusivities and permeabilities were assessed. It was found that the addition of DES enhances the transport of FF and HMF through the polymeric membrane support. In particular, the use of the DES consisting of thymol + lidocaine (in the molar ratio 2 : 1) impregnated in a polyethylene support resulted in enhanced transport for both FF and HMF, and is most interesting for (in situ) isolation of FF and HMF from aqueous solutions, e.g. in biorefinery processes.

This paper reports the preparation and performance characterization of new PdAg supported membranes with a porous protecting layer to protect the membrane surface from particles in a fluidized bed membrane reactor. Supported membranes with a selective layer of 1 µm and a protective layer have been prepared. Outstanding H2 permeance (5·10−6 mol m−2 s−1 Pa−1) and H2/N2 perm-selectivity (over 25,000) were measured at 400 °C and 1 bar of pressure difference. One membrane has been tested for more than 750 h in the presence of fluidized glass beads showing a decay in the perm-selectivity to approximately 5000, mainly due to sealing leakage. However, the protective layer was removed during this long-term test. Another membrane has been tested for more than 2000 h in a fluidized bed membrane reactor with a Rh reforming catalyst supported on promoted alumina in the bubbling fluidization regime. During tests with binary mixtures mass transfer limitations toward the membrane were observed due to large H2 permeance of the membranes.

Membrane reactors, combining production and separation of pure hydrogen in one vessel, outperform conventional fuel processors for small-scale hydrogen production. Among different membrane reactor concepts, the fluidized bed membrane reactor shows advantages in terms of optimal gas-catalyst contact, heat management and reduced bed-to-membrane mass transfer limitations; the drawbacks are the limits of the fluidization regimes which set minimum and maximum feed flowrates. In this work, a comprehensive model of a fluidized bed membrane reactor is developed. The reactor produces hydrogen (around 3 Nm3/h) for the 5 kWel-class PEMFC-based m-CHP systems using natural gas or bio-ethanol as feedstocks. Two different permeate options have been analyzed, namely vacuum and sweep gas configurations, together with detailed fluid-dynamics at the feed side. For the vacuum case the hydrogen output simulated with an ideal approach, i.e. without bubble-emulsion phase distinction, kinetic and mass transfer limitations, is overestimated by 10% with respect to the full detailed model. In the sweep gas configuration the detailed models haves the hydrogen produced by the ideal model. The gas diffusion through the thick porous support of the membranes is the most limiting phenomena, and the reactor size and operation conditions must be selected carefully considering this to reach the desired output.

In this work, the oxidation reaction of high loaded CuO-based materials was investigated under atmospheric and pressurized conditions. The oxygen transport capacity of the materials was firstly tested in the TGA and no losses greater than 5% were observed along 100 oxidation/reduction cycles. The kinetic parameters governing the oxidation reactions of the selected CuO-based materials were determined using a shrinking core model with chemical reaction control. The experimental results suggested that a SCM with chemical reaction control is able to predict the oxidation conversion of high loaded CuO-based materials in powder and pellet form. On the other hand, the effect of total pressure on materials reactivity was analyzed. The kinetic parameters obtained under atmospheric conditions were applied to fit the experimental data obtained under pressurized conditions. The results confirmed that the pressure has not an important effect on the oxidation kinetics of high loaded CuO-based materials and the parameters obtained at atmospheric pressure can be applied to study the oxidation under pressurized conditions.

This paper presents a new membrane reactor concept for ultra-pure hydrogen production with integrated CO2 capture: the membrane-assisted gas switching reforming (MA-GSR). This concept integrates alternating exothermic and endothermic redox reaction stages in a single fluidized bed consisting of catalytically active oxygen-carrier particles, by switching the feed between air and methane/steam, where the produced hydrogen is selectively removed via Pd-based membranes. This concept results in overall autothermal conditions and allows easier operation at high pressure compared to alternative novel technologies. In this work, the MA-GSR concept is demonstrated at lab scale using four metallic supported membranes (Pd–Ag based) immersed into a fluidized bed consisting of a Ni-based oxygen carrier. The performance of the reactor has been tested under different experimental operating conditions and high methane conversions (>50%) have been obtained, well above the thermodynamic equilibrium conversion of a conventional fluidized bed as a result of the selective H2 extraction, with (ultra-pure) H2 recoveries above 20% at relatively low temperatures (<550 °C). These results could be further improved by working at elevated pressures or by integrating more membranes. Even though the concept has been successfully demonstrated, further research is required to develop suitable membranes since post-mortem membrane characterization has revealed defects in the membrane selective layer as a consequence of the frequent exposure to thermal cycles with alternating oxidative and reducing atmospheres.

The hydrodynamic behavior of a bubbling gas-solid fluidized bed with vertically immersed membrane tubes has been studied using an endoscopic-laser PIV/DIA technique. The solids mass flux and hold-up profiles were determined together with the bubble phase properties (equivalent bubble diameter and bubble rise velocity) for different operating conditions and different membrane bundle configurations. The obtained results revealed that the lateral solids motion can be significantly hampered due to the presence of the membrane tubes resulting in a very high solids hold-up near the walls and much diluted regions in the middle of the bed. The obtained results from the experiments with a different number of membranes, membranes with a different outer diameter, and positioned with the bottom of the bundle at different axial positions in the bed, give guidelines to optimize the membrane configurations to achieve the highest lateral gas dispersion and optimal bubble breakage. These experimental results have also demonstrated the very important effect of tube spacers on the hydrodynamics. Moreover, the analysis of the bubble phase properties confirmed the enormous decrease in equivalent bubble diameter (up to a factor 3.5) for fluidized beds with immersed vertical membranes with spacers in comparison with a fluidized bed without internals, showing the great potential for improvement of the bubble-to-emulsion phase mass transfer rate.

Traces of CO in hydrogen rich gas streams poison the anode of proton exchange membrane fuel cells reducing their power output and decreasing the cell life. This paper investigates the CO selective oxidation in simulated reformate gas by using catalytic zeolite membranes. In particular, the CO removal efficiency was explored using catalytic membranes characterized by different permeation properties (prepared using different protocols) and loaded with the catalyst by means of cationic exchange and reduction process. The most promising experimental results are obtained with membranes prepared with small crystals and low concentration of zeolite suspension (during the seeding step) and with a hydrothermal treatment of 90 °C for 24 h. These membranes are characterized by lower permeance and showed interesting catalytic performance in terms of CO reduction and selectivity.

The sorption kinetics and capacities of CO2 and H2O were investigated for two different potassium-promoted hydrotalcite sorbents and potassium-promoted alumina. Thermogravimetric analysis (TGA) and packed-bed reactor (PBR) breakthrough experiments were performed using sequences of adsorption and desorption steps in different gas mixtures containing CO2 and H2O. Experiments were carried out at an operating temperature of 400 °C with different partial pressures ranging from 0.025 bar to 0.3 bar for CO2 and 0.1 to 0.3 bar for H2O respectively. It was found that a sorption mechanism with different adsorption sites, developed for one of the sorbents, also applies for the other sorbents where capacities are different and depending on the sorbent. From experimental results it was deduced that K2CO3 promotion is mainly responsible for a reactive CO2 adsorption site, which can only be regenerated with steam. The adsorption capacity for this site is enhanced for K2CO3 promoted alumina compared to K2CO3 promoted hydrotalcite. A second adsorption site for CO2, which can be regenerated with N2 is dominant on the K2CO3 promoted hydrotalcite with a high MgO content. This indicates that MgO is probably responsible for the formation of basic sites on the surface of the sorbent, which are relatively easily regenerated at the investigated experimental conditions. The results also show that the sorbent with the highest MgO loading has the highest cyclic working capacity under dry adsorption conditions, whereas the hydrotalcite-based adsorbent with a lower MgO content has the highest cyclic working capacity for CO2 at wet conditions and is therefore the preferred sorbent for sorption-enhanced water-gas shift applications.

The performance of perovskite membrane-assisted fluidized bed reactors for ultra-high purity hydrogen production through autothermal reforming of methane has been investigated using numerical simulations. Two different three-phase phenomenological models have been developed differing in their description of the mass transfer between the membranes and the emulsion, cloud and bubble phases, where the parameters in the oxygen permeation flux expression were determined from new experimental data. The calculation of the required oxygen-to-carbon ratio is based on overall enthalpy balance. The reactor performance without and with O2 permeable perovskite membranes have been investigated and compared. The two models of perovskite membrane-assisted fluidized bed reactors produce basically the same results, indicating that the external mass transfer from the membranes to the bulk of the fluidized bed is not rate limiting, but clearly show that the fluidized bed membrane reactor can largely outperform ordinary fluidized bed reactors for the autothermal reforming of methane. It has been demonstrated that with perovskite membrane-assisted fluidized bed reactors autothermal operation with a high CH4 conversion and H2 yield can be achieved with a relatively small catalyst inventory.

In this work a novel reactor concept referred to as Membrane-Assisted Chemical Looping Reforming (MA-CLR) has been demonstrated at lab scale under different operating conditions for a total working time of about 100 h. This reactor combines the advantages of Chemical Looping, such as CO2 capture and good thermal integration, with membrane technology for a better process integration and direct product separation in a single unit, which in its turn leads to increased efficiencies and important benefits compared to conventional technologies for H2 production. The effect of different operating conditions (i.e. temperature, steam-to-carbon ratio or oxygen feed in the reactor) has been evaluated in a continuous chemical looping reactor, and methane conversions above 90% have been measured with (ultra-pure) hydrogen recovery from the membranes. For all the cases a maximum recovery factor of around 30% has been measured, which could be increased by operating the concept at higher pressures and with more membranes. The optimum conditions have been found at temperatures around 600 °C for a steam-to-carbon ratio of 3 and diluted air in the air reactor (5% O2). The complete demonstration has been carried out feeding up to 1 L/min of CH4 (corresponding to 0.6 kW of thermal input) while up to 1.15 L/min of H2 was recovered. Simultaneously, a phenomenological model has been developed and validated with the experimental results. In general, good agreement is observed, with overall deviations below 10% in terms of methane conversion, H2 recovery and separation factor. The model allows better understanding of the behavior of the MA-CLR concept and the optimization and design of scaled-up versions of the concept.

In-situ IR technique was used to study the reversible adsorption of CO2 and H2O at elevated temperatures on a potassium-promoted hydrotalcite for its use in sorption-enhanced water-gas shift (SEWGS). It was found that mainly bidentate carbonate species are responsible for the reversible (cyclic) adsorption capacity of the sorbent. The presence of H2O can enhance the decomposition of bidentate carbonates bond to the stronger basic surface-sites. The basic strength of the involved adsorption sites for bidentate formation appears to be highly heterogeneous. At higher operating temperatures, reversible formation of bulk carbonates seem to participate in the reversible adsorption for CO2. The presence of H2O on the sorbent can lead to the formation of bi-carbonate, especially at lower operating temperatures of 300 °C. The transient absorbance of the main absorption bands for carbonate species identified during this study can be used in the development of a detailed description of the reversible adsorption/desorption kinetics reported before using thermogravimetric analyses.

Chemical looping combustion is especially competitive for electrical power generation with integrated CO2 capture when it is operated at high temperatures (1000–1200 °C) and high pressures (15 bar or higher). For these demanding conditions, dynamically operated packed bed reactors have been proposed, providing a good alternative to fluidized bed technology. This work addresses the importance of including the formation and reduction kinetics of spinel compounds to proper predict the packed bed reactor performance by validating a pseudo-homogeneous packed-bed reactor model to describe the redox kinetics of a CuO/Al2O3 oxygen carrier with experiments in a lab-scale packed bed reactor setup. A grain model describing the reaction kinetics of all solid species, including both spinel compounds (CuAl2O4 and CuAlO2), was included in a particle model and used to develop correlations for the effectiveness factor as a function of the particle conversion in order to account for internal solids concentration profiles and mass transfer limitations. The particle effectiveness factors were subsequently included in the source terms of the component mass balances of the reactor model accounting for all the reactions of the spinel compounds. Cyclic experiments (oxidation with air and reduction with a H2-N2 mixture) have been carried out in a lab-scale packed bed reactor with a 12.5 wt% CuO/Al2O3 oxygen carrier at different temperatures ranging from 600 to 1000 °C. The experimental results are well described by the packed bed reactor model, only when including the developed particle effectiveness factors to fully account for the kinetics of the formation and reduction of the spinel compounds. The results confirm that it is neccesary to include a detailed description of the redox kinetics at the particle level to be able to accurately estimate the breakthrough time, cycle time

Two different potassium-promoted hydrotalcite (HTC)-based adsorbents and a potassium-promoted alumina sorbent were investigated using thermogravimetric analysis (TGA) and different characterization methods in order to study CO2 and H2O adsorption capacity and kinetics. A higher Mg content improves the cyclic working capacity for CO2 due to the higher basicity of the material. The initial adsorption rate for CO2 is very fast for all sorbents, but for sorbents with higher MgO content, this fast-initial adsorption is followed by a slower CO2 uptake probably caused by the slow formation of bulk carbonates. A longer half-cycle time can therefore increase the CO2 cyclic working capacity for sorbents with a higher MgO content. Potassium-promoted alumina has a very stable CO2 cyclic working capacity at different operating temperatures compared to the potassium-promoted HTC's. Usually a higher operating temperature increases the desorption kinetics for a HTC-based adsorbent, but not for potassium-promoted alumina. HTC-based adsorbents show the highest cyclic working capacity for H2O. The adsorption kinetics for H2O are not influenced by the material composition, indicating that the mechanism behind the adsorption of H2O is different compared to CO2. Depending on the material composition, adsorption of steam at high operating temperatures (>500 °C) results in an irreversible decomposition of carbonate species. Steam can reduce the temperature where usually K2CO3 is irreversibly decomposed resulting in a significantly reduced cyclic working capacity, which is very important concerning the use of these sorbents for sorption-enhanced water-gas shift processes.

Palladium-based membrane-assisted fluidized bed reactors have been proposed for the production of ultra-pure hydrogen at small scales. Due to the improved heat and mass transfer characteristics inside such reactors, it is commonly believed that they can outperform packed bed membrane reactor configurations. It has been widely shown that the performance of packed bed membrane reactors can suffer from serious mass transfer limitations from the bulk of the catalyst bed to the surface of the membranes (concentration polarization) when using modern highly permeable membranes. The extent of concentration polarization in fluidized bed membrane reactors has not yet been researched in detail. In this work, we have quantified the concentration polarization effect inside fluidized bed membrane reactors with immersed vertical membranes with high hydrogen fluxes. A Two-Fluid Model (TFM) was used to quantify the extent of concentration polarization and to visualize the concentration profiles near the membrane. The concentration profiles were simplified to a mass transfer boundary layer (typically 1 cm in thickness), which was implemented in a 1D fluidized bed membrane reactor model to account for the concentration polarization effects. Predictions by the TFM and the extended 1D model showed very good agreement with experimental hydrogen flux data. The experiments and models show that concentration polarization can reduce the hydrogen flux by a factor of 3 even at low H2 concentrations in the feed (10%), which confirms that concentration polarization can also significantly affect the performance of fluidized bed membrane reactors when integrating highly permeable membranes, but to a somewhat lesser extent than packed bed membrane reactors. The extraction of hydrogen also affects the gas velocity and solids hold-up profiles in the fluidized bed.

Copper oxide supported on silica and supported on alumina are often used as oxygen carriers for chemical looping combustion owing to their very high reduction rates at lower temperatures and their very good mechanical and chemical stability at temperatures below 1000 °C compared to other oxygen carriers. In this work, a comprehensive experimental study has been carried out to better understand the reaction mechanism and quantitatively describe the reaction kinetics of the oxygen uncoupling reaction and the reduction and oxidation reactions under different reaction conditions. First, the oxygen uncoupling and reduction reaction kinetics of the CuO/SiO2 oxygen carrier was studied. A shrinking core type model (SCM) was developed that can well describe the oxygen uncoupling reaction rate and final conversion. Subsequently, a SCM and a simplified pseudo-homogeneous model was developed to describe the reduction kinetics of CuO/SiO2. Subsequently, the study was extended to investigate the reduction kinetics of CuO/Al2O3, where it was observed that the formation of tenorite spinel (CuAl2O4) and cuprite spinel (CuAlO2) strongly affects the overall reduction kinetics. Assuming that the reduction of CuO to Cu is independent of the support, the pseudo-homogeneous model was extended to include the reduction and oxidation kinetics of the spinel compounds, with which the experimentally determined redox kinetics could be well described. Regarding the CuO on Al2O3, The maximum temperature reached was 1000 °C in thermogravimetric analysis (TGA) without observing any sintering or melting effects. It can be due to the good stability with the Al2O3 support and the relatively small amount of CuO (13%). However, for CuO/SiO2 (70% CuO), the maximum temperature tested in the TGA was 900 °C, since at higher temperatures the sample was melting, due to the lower melting point of Cu. The main results of the study can be summarized as: i) the oxygen uncoupling and reduction/oxid

Pd-Ag supported membranes have been prepared by coating a ceramic interdiffusion barrier onto a Hastelloy X (0.2 µm media grade) porous support followed by deposition of the hydrogen selective Pd-Ag (4–5 µm) layer by electroless plating. To one of the membranes an additional porous Al2O3-YSZ layer (protective layer with 50 wt% of YSZ) was deposited by dip-coating followed by calcination at 550 °C on top of the Pd-Ag layer, and this membrane is referred to as a double-skin membrane. Both membranes were integrated at the same time in a single reactor in order to assess and compare the performance of both membranes under identical conditions. The membranes have first been tested in an empty reactor with pure gases (H2 and N2) and afterwards in the presence of a catalyst (rhodium onto promoted alumina) fluidized in the bubbling regime. The membranes immersed in the bubbling bed were tested at 400 °C and 500 °C for 115 and 500 h, respectively. The effect of the protective layer on the permeation properties and stability of the membranes were studied. The double-skinned membraned showed a H2 permeance of 1.55·10−6 mol m−2 s−1 Pa−1 at 500 °C and 4 bar of pressure difference with an ideal perm-selectivity virtually infinite before incorporation of particles. This selectivity did not decay during the long term test under fluidization with catalyst particles.

Traces of CO in hydrogen rich gas streams poison the anode of proton exchange membrane fuel cells reducing their power output and decreasing the cell life. This paper investigates the CO selective oxidation in simulated reformate gas by using catalytic zeolite membranes. In particular, the CO removal efficiency was explored using catalytic membranes characterized by different permeation properties (prepared using different protocols) and loaded with the catalyst by means of cationic exchange and reduction process. The most promising experimental results are obtained with membranes prepared with small crystals and low concentration of zeolite suspension (during the seeding step) and with a hydrothermal treatment of 90 °C for 24 h. These membranes are characterized by lower permeance and showed interesting catalytic performance in terms of CO reduction and selectivity.

This paper reports the preparation and performance characterization of new PdAg supported membranes with a porous protecting layer to protect the membrane surface from particles in a fluidized bed membrane reactor. Supported membranes with a selective layer of 1 µm and a protective layer have been prepared. Outstanding H2 permeance (5·10−6 mol m−2 s−1 Pa−1) and H2/N2 perm-selectivity (over 25,000) were measured at 400 °C and 1 bar of pressure difference. One membrane has been tested for more than 750 h in the presence of fluidized glass beads showing a decay in the perm-selectivity to approximately 5000, mainly due to sealing leakage. However, the protective layer was removed during this long-term test. Another membrane has been tested for more than 2000 h in a fluidized bed membrane reactor with a Rh reforming catalyst supported on promoted alumina in the bubbling fluidization regime. During tests with binary mixtures mass transfer limitations toward the membrane were observed due to large H2 permeance of the membranes.

Membrane reactors, combining production and separation of pure hydrogen in one vessel, outperform conventional fuel processors for small-scale hydrogen production. Among different membrane reactor concepts, the fluidized bed membrane reactor shows advantages in terms of optimal gas-catalyst contact, heat management and reduced bed-to-membrane mass transfer limitations; the drawbacks are the limits of the fluidization regimes which set minimum and maximum feed flowrates. In this work, a comprehensive model of a fluidized bed membrane reactor is developed. The reactor produces hydrogen (around 3 Nm3/h) for the 5 kWel-class PEMFC-based m-CHP systems using natural gas or bio-ethanol as feedstocks. Two different permeate options have been analyzed, namely vacuum and sweep gas configurations, together with detailed fluid-dynamics at the feed side. For the vacuum case the hydrogen output simulated with an ideal approach, i.e. without bubble-emulsion phase distinction, kinetic and mass transfer limitations, is overestimated by 10% with respect to the full detailed model. In the sweep gas configuration the detailed models haves the hydrogen produced by the ideal model. The gas diffusion through the thick porous support of the membranes is the most limiting phenomena, and the reactor size and operation conditions must be selected carefully considering this to reach the desired output.

In this work a novel reactor concept referred to as Membrane-Assisted Chemical Looping Reforming (MA-CLR) has been demonstrated at lab scale under different operating conditions for a total working time of about 100 h. This reactor combines the advantages of Chemical Looping, such as CO2 capture and good thermal integration, with membrane technology for a better process integration and direct product separation in a single unit, which in its turn leads to increased efficiencies and important benefits compared to conventional technologies for H2 production. The effect of different operating conditions (i.e. temperature, steam-to-carbon ratio or oxygen feed in the reactor) has been evaluated in a continuous chemical looping reactor, and methane conversions above 90% have been measured with (ultra-pure) hydrogen recovery from the membranes. For all the cases a maximum recovery factor of around 30% has been measured, which could be increased by operating the concept at higher pressures and with more membranes. The optimum conditions have been found at temperatures around 600 °C for a steam-to-carbon ratio of 3 and diluted air in the air reactor (5% O2). The complete demonstration has been carried out feeding up to 1 L/min of CH4 (corresponding to 0.6 kW of thermal input) while up to 1.15 L/min of H2 was recovered. Simultaneously, a phenomenological model has been developed and validated with the experimental results. In general, good agreement is observed, with overall deviations below 10% in terms of methane conversion, H2 recovery and separation factor. The model allows better understanding of the behavior of the MA-CLR concept and the optimization and design of scaled-up versions of the concept.

The hydrodynamic behavior of a bubbling gas-solid fluidized bed with vertically immersed membrane tubes has been studied using an endoscopic-laser PIV/DIA technique. The solids mass flux and hold-up profiles were determined together with the bubble phase properties (equivalent bubble diameter and bubble rise velocity) for different operating conditions and different membrane bundle configurations. The obtained results revealed that the lateral solids motion can be significantly hampered due to the presence of the membrane tubes resulting in a very high solids hold-up near the walls and much diluted regions in the middle of the bed. The obtained results from the experiments with a different number of membranes, membranes with a different outer diameter, and positioned with the bottom of the bundle at different axial positions in the bed, give guidelines to optimize the membrane configurations to achieve the highest lateral gas dispersion and optimal bubble breakage. These experimental results have also demonstrated the very important effect of tube spacers on the hydrodynamics. Moreover, the analysis of the bubble phase properties confirmed the enormous decrease in equivalent bubble diameter (up to a factor 3.5) for fluidized beds with immersed vertical membranes with spacers in comparison with a fluidized bed without internals, showing the great potential for improvement of the bubble-to-emulsion phase mass transfer rate.

For the first time, 12 different supported deep eutectic solvent (DES) liquid membranes were prepared and characterized. These membranes consist of a polymeric support impregnated with a hydrophobic DES. First, the different membranes were characterized and their stability in water and air was determined. Subsequently, the supported DES liquid membranes were applied for the recovery of furfural (FF) and hydroxymethylfurfural (HMF) from aqueous solutions. The effects of substrate properties (e.g. pore size), DES properties (e.g. viscosity) and concentrations of FF and HMF in the feed phase on the observed diffusivities and permeabilities were assessed. It was found that the addition of DES enhances the transport of FF and HMF through the polymeric membrane support. In particular, the use of the DES consisting of thymol + lidocaine (in the molar ratio 2 : 1) impregnated in a polyethylene support resulted in enhanced transport for both FF and HMF, and is most interesting for (in situ) isolation of FF and HMF from aqueous solutions, e.g. in biorefinery processes.

The performance of perovskite membrane-assisted fluidized bed reactors for ultra-high purity hydrogen production through autothermal reforming of methane has been investigated using numerical simulations. Two different three-phase phenomenological models have been developed differing in their description of the mass transfer between the membranes and the emulsion, cloud and bubble phases, where the parameters in the oxygen permeation flux expression were determined from new experimental data. The calculation of the required oxygen-to-carbon ratio is based on overall enthalpy balance. The reactor performance without and with O2 permeable perovskite membranes have been investigated and compared. The two models of perovskite membrane-assisted fluidized bed reactors produce basically the same results, indicating that the external mass transfer from the membranes to the bulk of the fluidized bed is not rate limiting, but clearly show that the fluidized bed membrane reactor can largely outperform ordinary fluidized bed reactors for the autothermal reforming of methane. It has been demonstrated that with perovskite membrane-assisted fluidized bed reactors autothermal operation with a high CH4 conversion and H2 yield can be achieved with a relatively small catalyst inventory.