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Metal-based supports require specific pre-treatments to reach the surface quality needed for achieving thin Pd layers deposition without defects. Hastelloy X supports with high surface roughness and large pore diameter are acquired and pre-treated via polishing and chemical etching. They are then asymmetrically filled with α-Al 2 O 3 of decreasing particle size (18 μm, 5 μm and 1.5 μm) and equipped with a γ-Al 2 O 3 interdiffusion barrier. Each pre-treatment step is thoroughly characterized and elucidated with ANalysis Of VAriance (ANOVA) as statistical tool, introducing a hybrid observational-statistical approach to infer on a population of membrane supports. The analysis allowed to set average surface roughness (Ra) < 0.8 μm, average profile height (Rz) < 7 μm, in-pore leveling (Δ) < 6 μm, as targets for support pre-treatments reproducibility. The target average pore diameter after asymmetric filling was identified as 100–500 nm, while the target average pore diameter after interdiffusion barrier deposition was below 100 nm. The most effective particle size for in-pore leveling was identified as ≤ 5 μm, and the most effective particle size for average pore diameter reduction as 18 μm. [Display omitted] • 20 Hastelloy X porous supports, were successfully pre-treated to increase their suitability for Pd deposition via electroless plating. • The operated pre-treatments were polishing, etching, symmetric and asymmetric filling with α-Al 2 O 3 particles and γ-Al 2 O 3 interdiffusion barrier deposition. • A Design of Experiment coupled with ANalysis of VAriance as statistical analysis tool was successfully applied. • Suitable targets: Ra <0.8 μm, Rz < 7 μm, average pore diameter after asymmetric filling ∼100–500 nm. [ABSTRACT FROM AUTHOR]

The theoretical approach for the bubble-to-emulsion phase mass exchange in bubbling gas-solid fluidized beds developed by Davidson and Harrison in the early 60’s is still widely applied in phenomenological models, mainly because of lack of more detailed experimental data to improve the description. In this study a novel infrared transmission technique that allows the direct and non-invasive measurement of gas concentration profiles inside bubbles with a high temporal resolution has been used for the validation of the theoretical description for the gas exchange. At first, the experimental technique has been further improved concerning the selective removal of particles raining through the bubbles, as well as the reconstruction of tracer gas concentration profiles throughout the gas bubble. The bubble-to-emulsion phase mass transfer coefficients have been measured by injecting tracer gas bubbles into incipiently fluidized beds and beds at freely-bubbling conditions, for beds consisting of glass beads of different particle size and with different injected bubble diameters. The results show that the Davidson and Harrison approach can reasonably well describe the mass exchange for isolated bubbles injected into a bed at minimum fluidization conditions. However, experiments carried out in a freely bubbling bed have shown that the mass exchange rate is considerably enhanced due to the increased gas through-flow through the bubbles. An empirical correlation (with deviations within only 20%) for the volumetric bubble-to-emulsion phase mass transfer coefficient has been developed based on the bubble size and superficial gas velocity, where it is noted that in this work the convective contribution in the mass exchange is dominant. [ABSTRACT FROM AUTHOR]

Copper oxide on alumina is often used as oxygen carrier for chemical looping combustion owing to its very high reduction rates at lower temperatures and its very good mechanical and chemical stability at temperatures below 1000 °C. In this work, the redox behaviour of CuO/Al 2 O 3 has been studied in great detail together with the redox behaviour of CuO/SiO 2 to identify the main phenomena affecting the observed redox kinetics. Combination of TGA results with detailed characterisation with XRD of the oxygen carriers at different stages during the redox cycling allowed elucidating the causes for the sudden decrease in the reaction rate observed at higher conversions for the CuO/Al 2 O 3 oxygen carriers. The main results of the study can be summarized as: i) oxidation reaction reaches always full conversion independent of the reaction temperature; ii) reduction reaction reaches only full conversion at very high temperatures, showing a significant decrease in the reaction rate at lower temperatures at higher particle conversions; iii) the observed sudden decrease in the reduction rate is related to the spinel reduction of CuAl 2 O 4 and CuAlO 2 . [ABSTRACT FROM AUTHOR]

Copper oxide on alumina is often used as oxygen carrier for chemical looping combustion owing to its very high reduction rates at lower temperatures and its very good mechanical and chemical stability at not too high temperatures. In this work, the redox kinetics of CuO/Al 2 O 3 have been studied at elevated pressures and temperatures. All the experiments have been started under the same initial conditions to assure the same starting point. While other studies reported a negative effect of the total pressure on the redox kinetics, this study shows that this negative effect of the pressure is most probably caused by external mass transfer limitations in previous studies. Additionally, as long as external mass transfer limitations are prevented, the total pressure at which the reduction is performed does not affect the redox kinetics nor the morphological and chemical structure of the oxygen carrier. The sudden decrease in the reduction rate at higher particle conversions was not influenced by the operating pressure and was attributed to limitations in the spinel reduction kinetics. [ABSTRACT FROM AUTHOR]

To enable the investigation of the hydrodynamics of gas–solid fluidized bed reactors at high-temperatures and reactive conditions, a new non-invasive experimental technique has been developed, based on the extension of Particle Image Velocimetry (PIV) coupled with Digital Image Analysis (DIA) using dedicated high-temperature endoscopes for image recording and laser illumination. The new endoscopic-laser PIV/DIA technique (ePIV/DIA) allows to determine simultaneously information from the emulsion and bubble phase with high spatial and temporal resolution in a pseudo-2D columns. The ePIV/DIA technique with single-source laser illumination has first been thoroughly validated at cold-flow conditions by comparison with a standard PIV/DIA technique with LED-illumination, showing very good agreement of the results in terms of particle velocity and solids mass flux profiles. The technique has subsequently been applied to fluidized beds in the bubbling fluidization regime at elevated temperatures to demonstrate its unique possibilities to measure detailed bed hydrodynamics at elevated temperatures. [ABSTRACT FROM AUTHOR]

Chemical-looping combustion is an emerging technology for power production with integrated CO 2 capture. With this combination, the energy penalty is expected to be relatively low, provided that the reactors are operated at elevated pressures (20 bar). Packed bed reactors can better accommodate high pressures compared with interconnected fluidized bed systems, while the challenging gas/solid separation is circumvented. In this work, CLC is demonstrated in a lab scale pressurized packed bed reactor using NiO/CaAl 2 O 4 as oxygen carrier material. H 2 and syngas with a typical composition obtained from coal gasification are used as fuel in the reduction step. The pressure has been varied between 2 and 7.5 bar, while it is demonstrated that the pressure has quite a small effect on the overall performance of the CLC reactor. The experiments are well described by a one-dimensional pseudo-homogeneous reactor model, with which it is shown that the required high temperatures for power production can be reached in case the reactor is scaled-up (decreasing the heat losses). A drawback of the oxygen carrier used is that the reduction kinetics depend on the temperature during the previous oxidation, which has been fixed during all the experiments. The reduction kinetics decrease with the oxidation temperature, which is probably caused by interaction with the support material and therefore some further modifications on the support material are required for high temperature applications. In case the process is carried out with syngas and steam, the heat management strategy has to be adapted because of the heat produced by the water gas shift reaction. [ABSTRACT FROM AUTHOR]

The hydrodynamic behaviour of a pseudo-2D Two-Section Two-Zone Fluidized Bed Reactor (TS-TZFBR) with an immersed tube bundle in its lower zone has been studied using non-invasive Particle Image Velocimetry (PIV) and Digital Image Analysis (DIA). Coupled porosity distribution maps from DIA post-processing and solids velocity vector fields from PIV analysis allowed the reconstruction of the transient and time-averaged solid fluxes along the bed. Six different tube bank configurations at several different superficial gas velocities have been tested to evaluate the hydrodynamic behaviour within the lower zone of the TS-TZFBR. The solids axial mixing along the vertical bed position has been quantified for this novel reactor configuration. Besides, the effect of the internals on the gas-solid mass transfer has been estimated by means of bubble size. A five-staggered tube bundle configuration was able to diminish the average bubble size by 30% within the lower bed zone at usual TS-TZFBR gas flow rates, u gas / u mf =3.0, without increasing the solids circulation time dramatically. [ABSTRACT FROM AUTHOR]

Chemical looping combustion of syngas has been investigated in a pressurized dynamically operated packed bed reactor using ilmenite as oxygen carrier. The combustion of both hydrogen and CO separately and in a typical syngas mixture over ilmenite have been experimentally tested in a relatively large laboratory-scale set-up and supported by numerical simulations. It has been found that wet syngas has to be used as reducing fuel to avoid excessive carbon deposition that reduces the CO 2 capture efficiency of the system. The oxygen carrier particles have been demonstrated to be active for the CLC of syngas and the experimental results can be well described by a pseudo-homogeneous reactor model when properly accounting for the heat losses and the heat exchange with the reactor walls and thermocouples. The reactor system has been used up to 7 bar demonstrating that pressurized CLC can be easily accommodated in packed bed reactors. A maximum temperature rise of 340 °C has been obtained in the reactor, which is in good agreement with the theoretical prediction when accounting for the heat losses toward the reactor and thermocouple bodies. [ABSTRACT FROM AUTHOR]

• Biomass from contaminated soils to renewable energy production. • Study for the choice of the most performing material for a fluidized bed gasifier. • The metals release from bed materials was never properly assessed up to now. • Study of TGA – ICP/MS method to predict the syngas contamination from heavy metals. The interaction between biomass from plant assisted bioremediation processes PABR contaminated with heavy metals and the bed materials used in Fluidized Bed Gasifier FBG systems was experimentally studied to identify the origin of the metals detected in syngas and/or solid residues, and affecting the quality of the produced fuels and biochar. The characteristics of an arboreal (poplar pruning) and an herbaceous biomass (Arundo Donax), both previously used in phytoremediation processes, were evaluated. The bed materials have been identified among those most used in pyrogasification processes, such as olivine, K-feldspar, kaolinite and calcite. The simulation of the process and the sampling of the syngas was carried out by means of an instrumental apparatus composed of TGA-DSC connected with a system of bubblers for the capture of heavy metals HM. The analysis of the matrices and the bubbled solutions in ICP-MS allowed to experimentally evaluate quantity and composition of HM released. The analyses showed that calcite gives the best results for both arboreal and herbaceous biomass but it has the disadvantage of losing about 55 % in weight during the process, releasing CO and CO 2 and becoming CaO. The criteria for choosing the most suitable material for the bed of an arboreal or herbaceous biomass gasification were carried out mainly on the basis of the heavy metals released during the process. The study provides useful results for the assessment of the bed materials in FBG conversion process using PABR biomass. From a comparison between all the parameters considered and the Principal Component Analysis (PCA) results, it emerges that K-feldspar represent the best optimization for the materials that can be used in FBG beds both in the case of arboreal and herbaceous plants, while olivine is particularly effective only with arboreal biomass. [ABSTRACT FROM AUTHOR]

A novel experimental technique using a high speed Infrared (IR) camera combined with an improved Digital Image Analysis (DIA) method for non-invasive concentration measurement with high spatial and temporal resolution has recently been developed by Dang et al. (2013). This paper reports the extension of the IR technique to freely bubbling and turbulent fluidization regimes to investigate and quantify lateral gas mixing characteristics in gas-solid fluidized beds. The mechanism of lateral gas mixing in the bubbling regime studied with the novel technique is in good agreement with values reported in the literature. The experimental results, interpreted with a plug flow model with superimposed dispersion for a homogeneous flow, show that the lateral gas mixing coefficient first increases with the increase of superficial gas velocities from the bubbling to the turbulent flow regime and then decreases for even higher velocities, which is consistent with earlier literature studies. The dependency of the lateral gas mixing coefficient on the Reynolds number using Amos׳ correlation (Amos and Mineo, 1993) has shown large discrepancies at low gas velocities (where the equation was extrapolated), while a good match was obtained at higher gas velocities. The experimental findings reported in this paper indicate that the novel IR/DIA technique can successfully be applied for mass transfer and gas mixing studies in gas-solids multiphase flows. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different particles have been developed and tested for application in a packed-bed CLC reactor. [•] Ilmenite was chosen as base material due to its good reactivity with syngas, the natural availability and related low cost. [•] A suitable oxygen-carrier was developed using ilmenite as base material and Mn2O3 as additive. [•] No significant differences in the reduction and oxidation reactivity of the different granules were observed. [ABSTRACT FROM AUTHOR]

Abstract: Membrane-assisted micro-structured fluidized beds have been proposed as efficient membrane reactors and in particular for hydrogen production. However, very little information is available on the effects of gas permeation through the membrane on the gas back-mixing and mass transfer rates in this type of reactors. This study carefully investigates the gas back-mixing characteristics in a micro-fluidized bed and the influence of gas permeation (both addition and extraction) through flat membranes installed in the left and right walls confining the fluidized bed. The tracer gas injection (stimulus-response) method has been used combined with Particle Image Velocimetry and Digital Image Analysis techniques for additional insightful information on the solids flux profiles that strongly influence the gas back-mixing. The results of this study demonstrate that micro-structuring of the fluidized bed results in reduced gas back-mixing and thus in a more efficient membrane reactor configuration for hydrogen production because of the increased driving force for gas permeation. The results also provide some guidelines for the design of micro-structured fluidized bed membrane reactors in terms of preferred specific membrane area and particle size. [Copyright &y& Elsevier]

Highlights: [•] CLC with CuO/Al2O3 and syngas and air has been demonstrated experimentally. [•] Model predicts accurately only if kinetics describe the complete solid reduction. [•] CuO/Al2O3 is proven to catalyze the reversed water gas shift reaction. [•] H2O is more effective to suppress carbon deposition on CuO/Al2O3 than CO2. [•] The OC reaction rate is not permanently affected by exposure to H2S. [ABSTRACT FROM AUTHOR]

Highlights: [•] The feasibility of packed bed CLC with syngas as the fuel is assessed. [•] New operation strategies are discussed to use ilmenite as oxygen carrier. [•] High efficiency process can be obtained also with less active oxygen carriers. [Copyright &y& Elsevier]

Summary: Intraductal papillary mucinous neoplasms (IPMNs) are rare pancreatic tumors, accounting for less than 1-2% of all neoplasms of the pancreas. The main characteristic of IPMNs is their favorable prognosis, as these pre-malignant or malignant lesions are usually slow-growing tumors and radical surgery is frequently possible. According to the localization of the lesions, three different tumor types have been identified: the main-duct IPMN, the branch-duct IPMN and the mixed-type IPMN (involving both the main pancreatic duct and the side branches). IMPNs do not present pathognomonic signs or symptoms. The obstruction of the main pancreatic duct system may cause abdominal pain and acute pancreatitis (single or recurrent episodes). The tumor may be incidentally discovered in asymptomatic patients, particularly in those with branch-duct IPMNs. In clinical practice, any non-inflammatory cystic lesion of the pancreas should be considered as possible IPMN. Computed tomography, magnetic resonance imaging with cholangiopancreatography and endoscopic ultrasonography can localize an IPMN and assess its morphology and size. The choice between non-operative and surgical management depends on the risk of malignancy and on the definitive distinction between benign and malignant IPMNs. Main-duct IPMNs have a high risk of malignant degeneration, especially in older patients. The clinical and radiological features, as well as treatment and outcome, of eight patients with IPMN (five with main-duct, two with branch-duct and one with mixed-type) observed by the authors over the last ten years are presented. [Copyright &y& Elsevier]

Abstract: The Two-Zone Fluidized Bed Reactor (TZFBR) is an effective solution to integrate reactions and catalyst regeneration in a single fluidized bed reactor. In the present study an experimental investigation on the fluid dynamics of a Two Section TZFBR is presented. Bubble and particle fluidization properties have been analyzed for this new reactor concept using a combination of two non-invasive techniques, viz. Digital Image Analysis (DIA) coupled with Particle Image Velocimetry (PIV) in a pseudo-2D TS-TZFBR. Results show how the reactor geometry affects the average equivalent bubble diameter and bubble velocity profiles, as well as the particle circulation patterns (between the two zones). It has been found that channeling and local defluidization phenomena are strongly influenced by the particle diameter, which therefore plays a key role in the design of an optimal geometry of a TS-TZFBR. [Copyright &y& Elsevier]

Abstract: A combined reactor and particle model was developed with which the effect of mass and heat transfer limitations inside the oxygen carrier particles on the axial concentration and temperature profiles in packed bed CLC could be correctly accounted for. It was concluded that during the oxidation cycle, the relevance of heat transfer limitations is negligible, but that resistances due to internal diffusion may play a significant role. This effect was found to be even stronger with the reduction cycles, where the effectiveness of the oxygen carrier particle was affected by higher activation energies and a low reaction order. With these models, more reliable predictions of the axial concentration and temperature profiles in packed bed CLC can be given, which are necessary to arrive at a proper design and a quantitative assessment of the suitability of packed bed CLC. [Copyright &y& Elsevier]

Abstract: The characteristics of the rate of reduction and oxidation that oxygen carrier particles undergo in chemical looping combustion processes are investigated from a theoretical point of view. An advanced numerical model was developed in which the effects of reaction kinetics and internal and external mass and heat transfer processes were incorporated in detail. It was found that with traditional models describing non-catalytic gas–solid reactions, e.g. the shrinking core or the homogeneous model, several important features of the process cannot be thoroughly captured. For the oxygen carrier system studied, it was found that the effect of Knudsen diffusion will usually be far more important than that of molecular diffusion. Finally, suggestions were made for the improvement of the average reaction rate via the implementation of a non-uniform distribution of the active solid material over the particle. With these results, improved understanding of the effect of mass and heat transfer processes on the rate at which oxygen carriers are reduced and oxidized has been obtained, which is essential for predicting the performance of CLC processes at larger scales. [Copyright &y& Elsevier]

Abstract: The response of the meiofauna communities to the discharge of synthetic-based mud (SBM) cuttings from an exploratory drill was analyzed in a deep-sea site (mean depth of 890m) in the Campos Basin, southeast Brazil. A total of 159 samples were taken on three sampling cruises: one pre- and two post-drilling (1 month and 1 year after drilling). One month after drilling, significant decreases in the meiofauna density and number of taxa were observed, as well as in nematode density and richness (number of families and genera); conversely, relative abundances of non-selective deposit-feeding nematodes, particularly the genus Sabatieria, increased significantly. Univariate and multivariate analyses indicate that the impacts on meiofauna were not restricted to a potential area of impact predicted by a model of cuttings dispersal; meiofauna changes just after the drilling agreed with the model in showing northward dispersal but over a larger area. The meiofauna, however, showed a weak correlation with the analyzed chemical parameters, such as hydrocarbon and metal concentrations. The results suggest that the effects of SBM drill cutting discharge on the meiofauna were probably related to physical changes in the substrate. Twelve months after drilling, most of the values of the meiofauna descriptors had returned to pre-impact period values. Nonetheless, the multivariate structure of meiofauna community was still significantly different, and the number of meiofauna taxa, densities of copepods, and epigrowth-feeder nematodes increased significantly. The increase of superficial forms of meiofauna in the deep sea may last until complete disaggregation of the cuttings. [Copyright &y& Elsevier]

Nailfold videocapillaroscopy (NVC) is one of the best diagnostic non-invasive imaging techniques to evaluate microcirculation in vivo and is increasingly employed in the field of rheumatology. Indeed, at present, the most important utility of NVC is in the identification of microvascular involvement in many rheumatic diseases, particularly in systemic sclerosis. More recently, this technique has been shown to be applicable to the study of many other extra-rheumatic diseases, such as arterial hypertension, diabetes mellitus, acromegaly, hyperthyroidism, cardiac syndrome X, primary biliary cirrhosis, Crohn's disease, psoriasis, familial Mediterranean fever. This article sets down the methodology of examination and normal pattern of capillary vessels and reviews the applications of NVC in clinical practice and its results in rheumatic and non-rheumatic diseases. [ABSTRACT FROM AUTHOR]

Two fluidized bed membrane reactor concepts for hydrogen production via autothermal reforming of methane with integrated CO2 capture are proposed. Ultra-pure hydrogen is obtained via hydrogen perm-selective Pd-based membranes, while the required reaction energy is supplied by oxidizing part of the CH4 in situ in the methane combustion configuration or by combusting part of the permeated H2 in the hydrogen combustion configuration (oxidative sweeping). In this first part, the technical feasibility of the two concepts has been studied experimentally, investigating the reactor performance (CH4 conversion, CO selectivity, H2 production and H2 yield) at different operating conditions. A more detailed comparison of the performance of the two proposed reactor concepts is carried out with a simulation study and is presented in the second part of this work. [ABSTRACT FROM AUTHOR]

The reactor performance of two novel fluidized bed membrane reactor configurations for hydrogen production with integrated CO2 capture by autothermal reforming of methane (experimentally investigated in Part 1) have been compared using a phenomenological reactor model over a wide range of operating conditions (temperature, pressure, H2O/CH4 ratio and membrane area). It was found that the methane combustion configuration (where part of the CH4 is combusted in situ with pure O2) largely outperforms the hydrogen combustion concept (oxidative sweeping combusting part of the permeated H2) at low H2O/CH4 ratios (<2) due to in situ steam production, but gives a slightly lower hydrogen production rate at higher H2O/CH4 ratios due to dilution with combustion products. The CO selectivity was always much lower with the methane combustion configuration. Whether the methane combustion or hydrogen combustion configuration is preferred depends strongly on the economics associated with the H2O/CH4 ratio. [ABSTRACT FROM AUTHOR]

Abstract: The ethanol steam-reforming reaction to produce pure hydrogen has been studied theoretically. A mathematical model has been formulated for a traditional system and a palladium membrane reactor packed with a Co-based catalyst and the simulation results related to the membrane reactor for both co-current and counter-current modes are presented in terms of ethanol conversion and molar fraction versus temperature, pressure, the molar feed flow rate ratio and axial co-ordinate. Although the counter-current mode does not always give an ethanol conversion higher than the one obtained in membrane reactor operated in co-current mode, in the first case it is always possible to extract more hydrogen from the reaction zone. With this theoretical analysis, different values of the operating parameters that allow to have a CO-free hydrogen stream and a complete recovery of the hydrogen from the lumen side of the reactor are investigated. [Copyright &y& Elsevier]

Abstract: This paper focuses on methane reaction with carbon dioxide to perform the dry reforming reaction in the temperature range 350–450°C. It is well known that CO2 in the atmosphere is the main cause of the greenhouse effect world-wide: several strategies are proposed for its consumption, for example pumping into subsoil (exhaust oil reservoirs) or into sea background. In this work, we propose CO2 consumption via chemical reaction with methane. In particular, the reaction of dry reforming of methane to produce syngas was carried out firstly in a traditional reactor, and subsequently in two different membrane reactors. A porous and a dense Pd–Ag tubular membranes have been used for this purpose. The reactors have been compared in terms of: experimental results regarding methane, carbon dioxide conversions, reaction products selectivities and hydrogen recovery. The experimental results achieved have also been compared with what we found in the specialised literature. [Copyright &y& Elsevier]

Abstract: In this experimental work, the acetic acid steam reforming reaction for producing pure hydrogen was studied in a Pd–Ag dense membrane reactor (MR). Two kinds of catalytic bed patterns have been considered: in the first pattern a Ni-based commercial catalyst has been packed inside the membrane lumen while, in the second one both a Ru-based and a Ni-based commercial catalysts have been packed together in the membrane lumen. The experimental tests have been performed in the temperature range 400–450°C and in the pressure range 1.5–2.5bar. The results are reported in terms of acetic acid conversion, hydrogen recovery and products selectivities. It has been found that the MR is able to give a rather high acetic acid conversion with a 30–35% hydrogen recovery. Moreover, the second catalytic bed pattern is able to increase the hydrogen production and to decrease the methane production with respect to the first pattern. [Copyright &y& Elsevier]

Abstract: The simulation of a dense Pd-based membrane reactor for carrying out the methane, the methanol and the ethanol steam reforming (SR) reactions for pure hydrogen production is performed. The same simulation is also performed in a traditional reactor. This modelling work shows that the use of membrane reactor is effective for carrying out the methane SR reaction, giving in the best conditions a conversion increase of 800% with respect to a traditional system, and can be really useful for carrying out the methanol SR reaction (25% conversion increase). Vice versa, the use of the membrane reactor in the ethanol SR reaction is still affected by the low catalytic activity. However, also for the ethanol SR reaction system, the use of the membrane reactor gives an increase of the ethanol conversion (30%) and a relatively high increase of the hydrogen yield. [Copyright &y& Elsevier]

Abstract: In this experimental work the influence of co-existing gases on the hydrogen permeation through a Ti–Ni–Pd membrane was studied. It was found that nitrogen, carbon dioxide and helium do not influence the hydrogen permeation through the dense membrane. However, carbon monoxide influences the hydrogen flux at each temperature investigated (400–500°C). The results show that for low CO concentration (i.e. at H2 upstream >80%), the hydrogen flux through the membrane decreases faster than linearly, while, at H2 upstream <80%, the slope is linear but smaller than the theoretical one. [Copyright &y& Elsevier]

Abstract: The ethanol steam-reforming reaction for the production of synthesis gas has been studied theoretically. A mathematical model has been formulated for a traditional reactor packed with a Co-based catalyst and then applied to a membrane reactor (MR) in which the hydrogen production is increased by removing the hydrogen produced from the reaction mixture through a highly selective (100%) palladium-based membrane. Our simulation results show that with MR it is possible to obtain both higher conversions of ethanol and higher hydrogen selectivities compared to those obtained in a traditional reactor operating at the same experimental conditions. The theoretical analysis provides a set of parameters allowing to maximize the (pure) hydrogen production and/or ethanol conversion if adopted in an experimental device. [Copyright &y& Elsevier]

Abstract: In this theoretical work the effects of the parameters governing the hydrogen permeation through the dense palladium membranes on the membrane reactor performances are studied. The model for the methane steam reforming was used as test reaction system and the effects of the parameters of the Richardson equation (, and ), on the reactor performances were studied. The effect of the hydrogen flux pressure and temperature dependence factors on the methane conversion and on the hydrogen recovery for both the co-current and counter-current modes are reported and discussed. [Copyright &y& Elsevier]

Abstract: Hydrogen permeation through a palladium membrane has been measured in the presence of several gases, such as CO, , , and Ar, both in the feed side and in the shell side of the (membrane) module. It has been found that CO molecules, remarkably inhibit hydrogen permeation. In particular, in the presence of carbon monoxide the permeation decreases with two different slopes: (I) for low CO concentrations, the hydrogen permeation decreases quickly (surface effects), whereas (II) for higher ones it decreases smoothly (dilute effect). Permeation of hydrogen, in the presence of the other gases, i.e. , and Ar, always decreases with the same slope (dilute effect). In order to describe the CO inhibition, a theoretical investigation has been proposed. In particular, the framework of the Density Functional Theory has been used. CO and Density Functional full optimisations on palladium clusters show that CO and molecules present two minima on the cluster surfaces with bond lengths of 2.0 and 3.8Å, respectively. The CO minima are much stable than minima, resulting in a surface effect on the hydrogen permeation through the membrane. [Copyright &y& Elsevier]

In this work a comparison between methanol steam reforming (MSR) reaction and ethanol steam reforming (ESR) reaction to produce hydrogen in membrane reactors (MRs) is discussed from an experimental point of view. Both reaction systems have been investigated by considering the influence of the membrane characteristics as well as the influence of the operating temperature. In the case of a dense membrane, the sweep gas flow rate and the different flux configurations have also been analysed. Experimental results, in terms of reactant conversions as well as hydrogen production and gases selectivity in MRs and in a traditional reactor (TR), are presented. Catalyst stability in both reaction systems has also been tested. [Copyright &y& Elsevier]

Background: Septic arthritis (SA) of the sternoclavicular joint (SCJ) is an uncommon form of arthritis, generally described in patients with predisposing risk factors such as primary or secondary immunosuppressive disorders, systemic or localized infections and central venous catheters. More rarely the infection occurs in patients without these risk factors, thus rendering difficult an early diagnosis. Material and methods: We report two cases of SA of the SCJ occurred in two patient, without known predisposing risk factors, hospitalized in our Internal Medicine Unit. Results: The clinical characteristics didn't significantly differ from clinical course of the disease occurring in patients with predisposing risk factors. Imaging techniques were useful to suspect diagnosis, but only fine-needle aspiration biopsy with culture of specimens leaded to identify the pathogen and its antibiotic sensitivity (in both patients Staphylococcus aureus). One patient was treated with surgical adequate curettage, drainage and intravenous methicillin, while the other one received only medical treatment with intravenous teicoplanin and ceftazidime. The outcome was uneventful with a complete recovery in both cases. Conclusions: Even if SA of SCJ is uncommon in subjects without predisposing risk factors, the clinician must have a high index of suspicion to consider this disease in differential diagnosis of arthritis also in previously healthy subjects with negative or unsettling instrumental investigations. In fact, prompt diagnosis is essential to obtain a successful outcome, avoiding the prolongation of the hospitalization and the sequelae of a chronic infection. [ABSTRACT FROM AUTHOR]

Purpose: This study was addressed to assess the clinical characteristics of patients presenting with chronic hyperamylasemia unrelated to pancreatic diseases (CHUPD). Almost all patients presenting with chronic hyperamylasemia undergo expensive, long, difficult, and often unnecessarily repeated diagnostic procedures. This is in conjunction with the poor knowledge of the fact that besides hyperenzymemia secondary to pancreatic diseases and systemic illnesses, various non-pathological forms of chronic hyperamylasemia without relevant pathologic consequence can occur in clinical practice.Material and Methods: Data of all patients with CHUPD were retrospectively reviewed (June 1997-December 2009). Fifty one patients were included in the study; median follow up was 48 months (range 8-112 months). Their pre-enrolment diagnoses were: chronic pancreatitis in 31 cases (60.7%) and recurrent pancreatitis in 13 cases (25.4%); the remaining 7 patients (13.7%) were without a specific diagnosis.Results: Our observations, supported by diagnostic procedures (Ca19-9 serum levels, abdominal ultrasonography, computed tomography and magnetic resonance, endoscopic retrograde cholangiopancreatography, and endoscopic ultrasonography) revealed that CHUPD was secondary to: a) benign pancreatic hyperamylasemia, 20 patients (39.2%); b) macroamylasemia, 18 patients (35.2 %) and c) salivary hyperamylasemia, 13 patients (25.4%).Conclusions: Due to the poor familiarity with CHUPD, the occurrence of this condition quite frequently leads to unnecessarily repeated diagnostic procedures. [ABSTRACT FROM AUTHOR]

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/Al 2 O 3 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 H 2 depletion, which were successfully described in the model using a film-layer model together with a Sherwood correlation. • A new comprehensive model was developed to describe the hydrogen flux through Pd-based membranes. • Data for permeation through supports are also presented • A set of permeation tests in different mixtures was performed with different membranes • The permeation data of the tests of each membrane is made available for other investigators via Zenodo [ABSTRACT FROM AUTHOR]

In this work, external mass transfer phenomena around hydrogen selective Pd-based membranes were analyzed experimentally and mathematically modelled. A supported Pd-Ag membrane was tested in pure hydrogen and in hydrogen/nitrogen mixtures using three different membrane lengths. Pressure, temperature, gas flow rate and feed composition were varied to obtain an elaborate dataset that could be used for analysis and modelling. Strong influences of concentration polarization and hydrogen depletion were observed. Various empirical correlations describing gas phase mass transfer around a tubular membrane from literature were tested, but none of them yielded a sufficiently accurate prediction of concentration polarization observed in the experiments. Therefore, a new Sherwood correlation was fitted using the dataset. The obtained correlation (Sh = 1.846 ∙ G z 0.60) showed significantly improved predictive behavior for the system used in this work and represents a potentially powerful tool for the modelling of membrane separators for pure hydrogen production. • H2 separation of Pd-based membranes is influenced by concentration polarization and hydrogen depletion. • In this work, extensive experiments were performed with a PdAg membrane at three different lengths. • The experimental dataset was used to evaluate the accuracy of multiple mass transfer correlations. • The new Sherwood correlation(s) showed significant improvement compared to literature. [ABSTRACT FROM AUTHOR]

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 H 2. 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. • An energy analysis of the Power-to-Liquid process has been performed. • The system reaches a global efficiency of 48.06 % and up to 38.71 % of Power-to-Kerosene efficiency. • It is possible to increase global efficiency up to 65.74 % and Power to kerosene efficiency to 53.60 %. [ABSTRACT FROM AUTHOR]

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. This work has been selected by the Editors as a Featured Cover Article for this issue. [ABSTRACT FROM AUTHOR]

Chemical looping combustion is especially competitive for electrical power generation with integrated CO 2 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/Al 2 O 3 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 (CuAl 2 O 4 and CuAlO 2 ), 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 H 2 -N 2 mixture) have been carried out in a lab-scale packed bed reactor with a 12.5 wt% CuO/Al 2 O 3 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, final amount of Cu present in the bed and the temperature rise in the reactor after reduction/oxidation reactions for packed-bed chemical looping combustion with a CuO/Al 2 O 3 oxygen carrier. [ABSTRACT FROM AUTHOR]

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/SiO 2 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/SiO 2 . Subsequently, the study was extended to investigate the reduction kinetics of CuO/Al 2 O 3 , where it was observed that the formation of tenorite spinel (CuAl 2 O 4 ) and cuprite spinel (CuAlO 2 ) 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 Al 2 O 3 , 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 Al 2 O 3 support and the relatively small amount of CuO (13%). However, for CuO/SiO 2 (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/oxidation of CuO/SiO 2 and CuO/Al 2 O 3 has been elucidated; (ii) a grain model that can describe the oxygen uncoupling and reduction reactions of CuO for different operating conditions has been developed; (iii) a pseudo-homogeneous grain model that can describe the redox kinetics of CuO/SiO 2 and CuO/Al 2 O 3 has been developed. [ABSTRACT FROM AUTHOR]

Metallic supports with sufficient surface quality to achieve highly selective thin Pd–Ag membranes require specific pre-treatments, are not readily available on the market and are generally very expensive. To reduce costs, rough and large media grade Hastelloy X filters have been acquired and pre-treated via polishing and chemical etching. The loss in gas permeance given by the polishing treatment proved fully recovered after chemical etching. A method to fill the large pores of the filters via aspiration of α-Al 2 O 3 water-powder suspension has been applied and characterized via imaging of the filled pores, inferential statistics, and capillary flow porometry measurements. The most suitable filler particle size for pore size distribution reduction has been identified as 18 μm, while a 5 μm filler proved optimal for further pore morphology improvement. The wide pore size distribution of the filters has thus been reduced up to 200 nm by filling with α-Al 2 O 3 particles of decreasing size, similarly to the ceramic supports used for thin Pd–Ag membranes deposition. A boehmite based interdiffusion barrier has been deposited, achieving further surface roughness reduction. A highly H 2 selective membrane has been obtained via simultaneous Pd–Ag plating on the pre-treated filter. [Display omitted] • A method to fill the pores of Hastelloy filters via aspiration of α-Al 2 O 3 water suspension has been developed. • The effect of α-Al 2 O 3 particle size on the surface quality has been studied with a statistical method. • The asymmetrical filling method can reduce the average pore size of the filters from 1.1 μm up to 200 nm. • A boehmite-based layer is used to change the surface quality and as interdiffusion barrier. • A highly H 2 -selective Pd–Ag membrane (∼40 000) has been obtained on the asymmetrically filled support. [ABSTRACT FROM AUTHOR]

The solids mass flux distribution and internal solids circulation rates in freely-bubbling gas-solid fluidized beds has been studied in detail in a pseudo-2D column. A non-invasive Particle Image Velocimetry (PIV) combined with Digital Image Analysis (DIA) technique has been further extended to investigate and quantify the gas and solids phase properties simultaneously for different particle types and sizes (all Geldart B type) at different fluidization velocities. It is found that the solids fluxes increase strongly, practically linearly, as a function of the vertical position and depend on the excess gas velocity but not on the particle size, while the most often used phenomenological two-phase fluidized bed models assume the vertical solids fluxes to be constant. To further investigate this important discrepancy, the underlying assumptions of the phenomenological models have been validated, especially concerning the average solids fraction inside the bubbles, the laterally and time-averaged axial bubble fraction profile (or visual bubble flow rate) and the wake parameter (the amount of solids carried along a bubble relative to the bubble volume). To this end, the PIV/DIA technique was further extended and a new method for the determination of the wake parameter is proposed. From the experimental results, it was concluded that i) the average solids fraction inside the bubbles is about 2.5–3% for glass beads and alumina particles and is practically independent of the excess gas velocity and particle size; ii) the measured laterally and time-averaged bubble fractions are considerably lower compared to often used correlations from literature, which would lead to a significant over-prediction of the visual bubble flow rate and iii) the wake parameter depends strongly on the bubble size and with the developed correlation the axial solids mass fluxes as a function of the vertical position can be well described. Finally, the influence of these findings was evaluated by performing a sensitivity analysis with an existing phenomenological model for fluidized beds with the new values and closures considering the case of the heterogeneously catalyzed steam methane reforming. With the developed findings and correlations the predictions with the two-phase phenomenological models can be further improved, especially concerning the hydrodynamics of the solids phase. [ABSTRACT FROM AUTHOR]

Oxidative coupling of methane (OCM) has been investigated as an interesting way to obtain higher hydrocarbons from natural gas. The aim of this article is to evaluate the reactor concepts for oxidative coupling of methane, from the 1980s through the current state of the art, giving a general insight into the reactor engineering possibilities and perspectives of application of OCM in large scale reactors. The concepts were classified according to the type of reactor bed, the heat management system, the oxygen feeding policy, the degree of integration with separation units, the relative cost, and the current demonstration on industrial scale. [ABSTRACT FROM AUTHOR]

This paper addresses the experimental demonstration and model validation of chemical looping reforming in dynamically operated packed-bed reactors for the production of H 2 or CH 3 OH with integrated CO 2 capture. This process is a combination of auto-thermal and steam methane reforming and is carried out at high pressure, as typical for reforming processes, and at relatively low to intermediate temperatures (ranging from 600 to 900 °C). The oxidation of the oxygen carrier is performed with air and the hot depleted air stream is fed to a gas turbine, which contributes to reduce the electricity demand. After oxidation, a low-grade fuel is used for the reduction of the oxygen carrier, e.g. off-gas from a PSA unit or non-condensable species from methanol synthesis and, when the bed is completely reduced, natural gas diluted with H 2 O and CO 2 is reformed while the reactor is cooled down. An experimental campaign has been carried out in a 2 kW th packed-bed reactor using 500 g of NiO supported on CaAl 2 O 4 as reforming catalyst and oxygen carrier. This material has demonstrated very high stability over > 400 h of consecutive redox and reforming cycles. Due to the flexibility of the process, dry, wet and steam reforming compositions have been tested during the reforming phase. A 1D reactor model has been validated with the obtained experimental results, including also a detailed thermal model to account for the inevitable heat losses of the system. The experimental and model results are in good agreement in terms of breakthrough curves and temperature profiles. The experimental campaign during reforming also confirmed the possibility to carry out the heat removal phase by means of endothermic methane reforming. The validated reactor model has subsequently been used for the simulation of different configurations in terms of heat management in which the different phases (oxidation, reduction and reforming) are simulated in series. In these analyses, the reactor design and performance have been compared for two plant configurations based on H 2 and CH 3 OH production integrated with CO 2 capture. For the case of H 2 production, the CH 4 conversion is 92% and all the CO 2 is captured from the plant, while for CH 3 OH production the CH 4 conversion reaches 90% and all carbon species, except CH 3 OH, are converted into CO 2 , which is separated with high purity. [ABSTRACT FROM AUTHOR]

Copper oxide on alumina is often used as oxygen carrier for chemical looping combustion owing to its very high reduction rates at lower temperatures and its very good mechanical and chemical stability at not too high temperatures. In this work, the redox kinetics of CuO/Al 2 O 3 have been measured and analysed with many consecutive reduction (50% H 2 , 50% N 2 ) and oxidation (air) cycles at different temperatures using thermogravimetric analysis. In all the redox cycles, a cyclic steady state in the redox kinetics is observed after several redox cycles, where a sudden decrease in the reaction rate is observed after a certain solids conversion, typically around 75%, depending in particular on the operating temperature. Models developed in the literature fail at predicting these redox kinetics and they are mostly shrinking core/grain type models with an ad-hoc combination and modification of chemical reaction and gas phase diffusion. The oxygen carrier was characterized in detail with different techniques including N 2 physisorption, XRD and SEM-EDX to investigate morphological changes in the particle over the redox cycles in order to better understand why all the models developed in literature fail. After the study we can conclude that i) gas-phase diffusion is not playing a limiting role on the redox kinetics despite significant morphological changes in the particle; ii) migration of copper from the inside of the particle to the surface of the particle does not occur or does not influence the kinetics; iii) oxygen uncoupling is not influencing the kinetics being equally fast for Cu 2 O and CuO, although it can be significant for the final maximum particle conversion; iv) solid phase oxygen diffusion limitations may be responsible for the observed drop in reaction rate. [ABSTRACT FROM AUTHOR]

The calcium-copper looping process is a novel concept proposed for hydrogen production from methane with integrated CO 2 capture. The heat required to drive the endothermic steam-methane reforming is supplied by in-situ simultaneous heat production from calcium carbonate formation, by which also CO 2 capture is achieved (calcium looping process). In the regeneration step, the heat required to regenerate the CO 2 sorbent is matched with in situ heat production through the reduction of copper oxide to copper (chemical looping process). The process is carried out in adiabatic fixed bed reactors and consists of three main process steps: (i) sorption enhanced reforming, (ii) oxidation of copper and (iii) calcination of CaCO 3 combined with the reduction of CuO. In this paper the process has been simulated in detail with a one-dimensional pseudo-homogeneous reactor model (PHM) and a reduced model has been developed (computationally enormously much faster and still sufficiently accurate) based on a sharp front approach to simplify further reactor and process design and optimization. Simulations with the PHM have been performed for the three steps of the process varying the temperature, pressure, solid composition, gas composition and flow rates. The outcomes of the model have been compared with calculations performed with the sharp-front approach. The reaction and heat exchange front velocities calculated with both models are in very good agreement. Process operability windows for all three process steps have been identified. The overall thermal efficiency and the carbon capture efficiency have been calculated, resulting in 73% and 80%, respectively. [ABSTRACT FROM AUTHOR]

The scope of this paper is the development and implementation of a safety risk assessment methodology to highlight hazards potentially prevailing during autothermal reforming of natural gas for hydrogen production in a membrane reactor, as well as to reveal potential accidents related to hydrogen under certain conditions. The newly developed methodology is able to cover all possible risk scenarios. The methodology was applied to a novel autothermal membrane fluidized bed reactor integrated within a micro-CHP system of 5 kWel with a PEM fuel cell. The system modelled is based on a prototype developed within the European ReforCELL project. A thorough safety risk assessment methodology was applied examining and evaluating the final outcomes of hydrogen release accident scenarios. The main conclusion of this analysis is that hydrogen may lead to a series of accident types that may pose a threat to the public safety, however, all considered scenarios fall well within the standard criteria, which indicates the adequate safety of this novel technology. [ABSTRACT FROM AUTHOR]

Recently, a novel two-stage reactorconfiguration for packed bedchemical-looping combustion (CLC) has been proposed and studied bynumerical simulations. This two-stage CLC consists of two pressurizedpacked bed reactors connected in series, where the first bed containsan oxygen carrier material which is reactive at relatively low temperatures(450 °C) such as CuO/Cu, while the second bed contains an oxygencarrier which is resistant to relatively high temperatures (typically1200 °C) such as NiO/Ni. In this work, this two-stage CLC concepthas been experimentally demonstrated using CuO/Al2O3and NiO/CaAl2O4as bed materials ina high-pressure, high-temperature packed bed reactor. The influenceof the operating conditions has been examined, and a validated reactormodel has been used to scale up the process to industrial scale. Thetwo-stage CLC concept is successfully demonstrated with a maximumtemperature of 839 °C in the second bed. The operating pressure,the throughput during the reduction cycle, and the fuel concentrationshave been found to result in small or negligible influences on themaximum temperature rise. This means that they do not affect the TS-CLCperformance as long as the cycle time is adopted such that the heatproduced in the first reactor bed is exactly transferred to the secondbed. It has also been demonstrated that operation at higher pressures(to reach a higher overall process efficiency) does not affect theperformance of the TS-CLC reactor. However, the fuel type (H2, syngas, CO, or CH4) strongly influences the temperatureincrease in the reactor, since it influences to what extent the oxygencarriers can be reduced. The experimental results could be well describedby a one-dimensional packed bed reactor model provided that the extentof heat losses and the response time of the thermocouples are properlytaken into account. The validated reactor model shows that the desiredgas flow rate at 1200 °C can indeed be produced after some smallchanges in the operating conditions and the active weight contentof the oxygen carriers. Therefore, TS-CLC can be regarded as a feasibletechnology for power production with inherent CO2capturewith high LHV efficiency. [ABSTRACT FROM AUTHOR]

Thin Pd–Ag layers have been successfully deposited on ceramic supports with controlled surface characteristics. The need for less fragile membranes and ease of sealing and connection leads to the study of metallic supports for thin Pd-based membrane development. Metallic supported membranes are prone to intermetallic diffusion issues so an interdiffusion barrier must be introduced. However, metallic supports with sufficient surface quality for direct membrane deposition are expensive and not readily available in the market. It is thus important to study how to improve surface roughness of commercially available rough metallic filters, in order to allow deposition of a smooth, delamination-free Pd–Ag layer. This work reports a first attempt towards a standardized preparation procedure for Pd-based membranes on cheap, rough, and unrefined Hastelloy X tubular filters. The focus is on surface roughness reduction, in order to allow the deposition of a smooth, uniform Pd–Ag selective layer. The surface roughness of the tubes is tuned via 1) polishing and 2) addition of a smoothening interdiffusion barrier layer based on a boehmite dip-coated dispersion. The polishing time was assessed by studying the average support's roughness variation, permeation behavior and ability to retain ceramic coating. It was found that the best trade-off between polishing extent and gas permeance of the support amounts to 6 h. Moreover, it was assessed that increasing the boehmite load in the interdiffusion barrier precursor solution leads to thicker layers and larger surface roughness reduction, but greater solution instability. 1,2%wt of boehmite load proved the best trade-off between layer reproducibility and support coverage. Different dipping-sintering routes were evaluated in order to improve surface's suitability for electroless plating: a single interdiffusion layer deposition route proved the most suitable for Pd–Ag deposition. The electroless plating performed onto the treated supports results in a continuous Pd–Ag layer, proving Pd–Ag deposition possible on the selected filters. • The surface characteristics of rough tubes have been tuned to a media grade that allows membrane deposition. • The polishing time was assessed by studying the average support's roughness. 6 h are enough to produce good supports. • Boehmite-based interdiffusion layers are used to change the surface quality and as interdiffusion barrier. • Thin Pd–Ag layers can be deposited on the modified supports. [ABSTRACT FROM AUTHOR]

Mathematical models of transesterification commonly assume that oil is a mixture of triacylglycerols, where each component has only one type of acid attached. This article aims to show how a different assumption on acid distribution affects the results of acylglycerols fraction composition. Experiments of fish oil ethanolysis have been performed at different enzyme loadings and ethanol concentrations, leading to enrichments from 35 % to 52 % of ω3 mass fraction in acylglycerols, by losing 12.1 % of ω3 as ethyl esters. A kinetic model is developed assuming both all acids of the same type on each acylglycerol and all acids randomly distributed on the available positions. The two different assumptions showed strong discrepancies on the acylglycerols fraction compositions predictions, demonstrating how the initial fatty acids distribution is important when an accurate description of the acylglycerols fraction is desired. • Fish oil ethanolysis experiments at different enzyme loadings and ethanol fractions. • Acylglycerol fraction is enriched in ω3 from 35 % to 52 %, losing 12.1 % of them. • Mathematical macro-kinetic model validated and used to optimize performance index. • New formulation of the model assumes random acids distribution on the acylglycerols. • Glycerides predictions are strongly influenced by assumptions on acids distribution. [ABSTRACT FROM AUTHOR]