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Current multistage CCU technologies using renewable electricity to yield fuels suffer from low energy efficiency and require large capital expenditures. To increase the efficiency of the whole process and reduce its cost, a possible innovative solution is represented by the combined capture and hydrogenation of CO2. The idea is to trap CO2 from a CO2-containing stream (e.g. combustion flue gases) using a dual functioning material (DFM) composed of a highly dispersed supported adsorbent which provides at the same time the CO2 storage function and methanation active element to produce CH4 upon reaction with renewable H2 [1-2]. This process is operated cyclically by alternating phases where the DFM is exposed to the flue gas and CO2 is selectively adsorbed, and phases where H2 is fed and the stored CO2 is hydrogenated to methane [2]. Notably, by eliminating a thermal swing process, the conversion of CO2 to SNG using DFMs constrains the energy input to only renewable sources (in the form of H2), thus allowing the CO2 capture and utilization processes to approach carbon neutrality while integrating more renewable energy into the grid [2]. In a highly innovative scheme aimed at the process intensification, the DFM represents a CO2 carrier that is continuously circulated from a sorption reactor to a methanation reactor and vice versa [3]. Dual interconnected fluidized bed technology appears perfectly suited to perform the chemical looping CO2 Capture and Methanation process since it allows the recirculation of DFM particles between two reactors and ensures their efficient and independent temperature control. Therefore, we set out to experimentally investigate the key features capable to boost the overall performance of DFMs based on Ru and alkali metal (oxides) supported on high surface area aluminas with suitable mechanical and attrition resistance to be used in interconnected fluidized bed reactors. The general scope is to produce synthetic methane via an innovative, renewable energy driven, catalytic looping process, demonstrating effectiveness and reduction of greenhouse gas emissions while also addressing economic, regulatory, environmental and (critical) raw material constraints, as well as socio-economic impact related to the proposed technological pathway.

The industrial processing of tomato leads to substantial amounts of residues, typically known as tomato pomace or by-products, which can represent as much as 10% by weight of fresh tomatoes. At present, these residues are either used as feedstock for animals or, in the worst case, disposed of in landfills. This represents a significant waste because tomato pomace contains high-value compounds like lycopene, a powerful antioxidant, cutin, which can be used as a starting material for biopolymers, and pectin, a gelling agent. This article presents an overview of technologies that valorize tomato by-products by recovering added-value compounds as well as generating fuel for energy production. These technologies include operations for extraction, separation, and exploitation of lycopene, cutin and pectin, as well as the processes for conversion of the solid residues to fuels. Data collected from the review has been used to develop a biorefinery scheme with the related mass flow balance, for a scenario involving the tomato supply chain of Regione Campania in Italy, using tomato by-products as feedstock.

According to RED II targets by 2030 the renewable energy consumption must be raised up to 32%, particularly 14% of the energy supplied for road and rail transport must be renewable. As part of renewable energy sources, residual biomass plays a significant role, because of its availability and the possibility of obtaining advanced biofuels and biochemical trough several thermochemical and biochemical processes, such as pyrolysis, gasification and aerobic digestion. The main challenge of using residual biomass is its properties variability (e.g., O/C ratio, ashes content, extractives, cellulose, hemicellulose, lignin and so on) according to type, geographic localization and seasonality. For this reason, properties and yields of the products are highly variable. Furthermore, the complexity of the processes involved in biomass valorization often makes the classical chemical-physical modelling approach very challenging. In this framework, the research community as well as the industrial sector are focusing their attention on the adoption of new provisional tools, based on advanced statistical methods, machine learning techniques and operative research techniques for decision-making support, in order to improve the sustainability utilization of the biomass resources. In particular, this work represents the first attempt to this new modelling approach, focusing its attention on the thermochemical valorization of residual biomass. The principal components analysis (PCA), which projects the original data in principal component (PC) space for assessing which input parameters have the highest score on the PC reducing the input data dimension, without losing valuable information, is used for the fast pyrolysis process. A broad database with about 450 observations is developed collecting data from scientific literature. The database includes both qualitative and quantitative information regarding main biomass characteristics (e.g., type, proximate and ultimate analysis), operative parameters (e.g., temperature, pressure, type of reactor) pyrolysis products and byproducts (e.g., yields, quality). PCA is applied to a subset of the original data considering only fast pyrolysis process, non-catalytic, in a fluidized-bed reactor with a temperature range of 450-550°C.

Bulk flow properties from shear analysis of compacted powders can be evaluated following different approaches. Experimental values of shear stresses obtained by conventional shear cells are traditionally used to build yield loci, from which the most relevant flow properties could be found. Such flow properties play an important role in determining their performance under fluidization conditions. In this work, a useful app, named cYield, was developed by using the new Matlab&rsquo, s App Developer environment. This tool enables users to calculate both linear (Coulomb) and non-linear (Warren&ndash, Spring) yield loci as the best fitting of the &sigma, &tau, experimental shear points. It also provides a wide range of statistical information related to the quality of the outcomes obtained. The different features of the tool are presented, and the crucial steps for the execution of its calculations are illustrated. Moreover, it has been applied for the yield loci analysis of four different materials traditionally used in manufacturing processes. The results confirm that the flow behavior of many industrial powders, especially if cohesive, is better described by a non-linear yield locus.

In order to understand the factors responsible for changes in the fluidization behaviour of industrial particles at high temperatures, an experimental campaign was performed using a 140 × 1000 mm heated gas fluidized bed. Five powder cuts sieved out of the same mother powder covering Group B, A and C of Geldart's classification were investigated over a range of temperatures from ambient to 500 °C. The results show that the mean size distribution affects significantly the fluidization behaviour of the materials investigated. In particular, significant differences were observed in the fluidization behaviour of the coarsest samples (Group B-A) and finest samples (Group A-C). The minimum fluidization conditions were compared with the prediction of the Ergun equation. The comparison was satisfactory only when accounting for the experimental values of the bed voidage. In fact, the non-monotonic trend of the minim velocity for fluidization with increasing temperature cannot be explained only with the effects of temperature on the bed fluid dynamics. But several others are the observed effects on the fluidization behaviour due to the temperature rise that can be ascribed to the enhanced interparticle forces: 1) the increase of the peak of pressure drops, close to the minimum for fluidization, in the fluidization curve at increasing gas velocities; 2) the increase for the finest samples of the hysteresis in the fluidization curves, considering the fluidization and defluidization branches of the curve; 3) a greater tendency of the bed to expand homogeneously; 4) the increasing difference between the parameters of the Richardson-Zaki equation found with a fitting procedure on the experiments and those found using the Richardson-Zaki correlations and the theoretical terminal velocity. Furthermore, in the cases where larger interparticle forces were expected, the X-Ray facility allowed to identify different internal structures within the bed. Mostly vertical channels but also, in the case of the finest powder tested, horizontal channels.

Two ceramic powder samples having different compositions of surface impurities and particle size distributions were considered. These two samples resulted from a high temperature fluidized bed reactor which in its operation showed changes of working condition that might be attributed to the onset of strong interparticle forces. The flow behaviour of these powders was characterized by the High Temperature Annular Shear Cell (HT-ASC), between ambient temperature and 500 °C. Furthermore, a model is developed to relate the change of the powder flowability to the formation of a liquid phase due to the melting of particle impurities present on the particle surface. In particular, the model is used to predict, on the base of the salt composition, the intensity of the interparticle forces at different temperatures. The interparticle forces predicted by the model can be compared with those that can be inferred from the powder flow properties measured with the HT-ASC. Therefore, it is demonstrated that it is possible to derive a theoretical model to predict interparticle forces in a particulate material relevant to fluidized bed reactor, on the basis of the impurities composition. Furthermore, it is demonstrated the possibility to correctly estimate the intensity of average interparticle forces in the same kind of material by the interpretations of bulk flow properties measured with a shear tester, even in the case in which capillary forces take the place of the much weaker van der Walls forces. More in general, the paper suggests a method by which powder rheology can be used to indirectly evaluate the effects of the interparticle forces on fluidization processes even in case in which strong capillary interaction occur.

The removal of carbon dioxide from flue gases can be achieved through adsorption separation technologies. In this framework, zeolites have shown promising results for the separation of CO 2 from gas mixtures and can potentially be used for both TSA/PSA processes. In particular, natural zeolites are inexpensive and can be viable sorbents. The aim of this work is the characterization of a non-synthetic tuff zeolite that could be used as carbon dioxide adsorbent. In order to assess changes in its structural and gas adsorption properties, the tuff was treated with acid solutions. Both the natural and acid treated samples were fully characterized from a chemico-physical point of view: pore size distribution, specific surface, SEM and XRD analyses were performed. The CO 2 adsorption capacity of the samples was measured in a lab-scale fixed bed reactor. Breakthrough curves were determined at a fixed flow rate (15Nl/h) using mixtures of CO 2 and N 2 with different CO 2 concentrations (5-20%vol.). Then, the adsorption isotherms were obtained from experimental data. The experimental results show that tuff, in particular if properly pre-treated, is a promising alternative to synthetic zeolites in adsorption processes for CO 2 removal.

CO2 adsorption on solid sorbents under dynamic conditions is driven by a number of factors, among them textural features (pore volumes, pore size distribution, surface area...), surface chemistry (polarity, presence of active site and/or unsaturated coordinative sites...) and the overall active sites accessibility. Depending on the strength of the interaction with CO2 (chemisorption or physisorption), solid sorbents are broadly divided in two groups, although a sharp distinction between the two phenomena (in many cases concurrent) is obviously not possible. CO2 adsorption data acquired in a lab-scale fixed bed reactor under dynamic conditions and in typical conditions of post-combustion CO2 capture on materials produced from the work-up of carbonized rice husk were here reported and compared with pertinent literature on commercial and ad- hoc synthetized sorbents. Some attempts to correlate adsorption capacities and materials' textural properties or other relevant adsorption parameters have been also proposed.

Even though the performances of CO2 adsorbent materials for temperature swing adsorption (TSA) are typically assessed based on the equilibrium adsorption capacity, the actual feasibility of a sorbent in real applications cannot be reliably inferred from only this parameter. Indeed, more than the maximum CO2 uptake achievable at equilibrium, it is necessary to know the actual amount of CO2 that can be captured in a full adsorption/desorption cycle, namely the difference between the amount of CO2 adsorbed under adsorption and desorption conditions, which is defined as the CO2 working capacity. In this work, dynamic breakthrough and regeneration tests have been performed using a commercial activated carbon in a lab-scale TSA sound-assisted fluidized bed apparatus in order to experimentally evaluate the CO2 working capacity. In particular, the effect of adsorption/desorption temperatures (18 - 150 °C) and CO2 partial pressure (0.05 - 0.20 atm) has been evaluated.

CO2 adsorption on a yellow tuff has been studied, by performing dynamic breakthrough experiments in fixed bed, focusing on the thermodynamics and kinetics of the process. The effect of both temperature (25 - 150 °C) and CO2 partial pressure (0.01 - 0.20 atm) has been assessed. The CO2 adsorption isotherms in the low pressure region typical of combustion flue gases are more accurately described by the Freundlich equation than by the Langmuir one, thus indicating a multilayer and heterogeneous surface binding. The obtained values of the main thermodynamic parameters suggested that the adsorption process is spontaneous, exothermic and physical in nature. The pseudo-first order kinetic model better fitted the experimental data at all the investigated adsorption temperatures than the pseudo-second order does. Based on the thermodynamic properties, some insights into the process strategy for post-combustion capture (i.e. pressure vs vacuum swing) are derived.

Thermochemical energy storage (TCES) is considered as a promising technology to accomplish high-energy storage efficiency in concentrating solar power (CSP) plants. The high temperatures achievable by CSP are used to drive an endothermic chemical reaction, whose products are stored separately to be employed when needed for carrying out the exothermic reverse reaction, which releases the heat previously used. Among all the alternatives, the calcium-looping (CaL) process, based on the reversible calcination-carbonation of CaCO3, is one of the most promising solution due to the high energy density achievable and the extremely low price, nontoxicity, and wide availability of natural CaO precursors such as limestone. It is typically performed in two interconnected fluidized beds, one acting as carbonator and the other as calcinator. In particular, aiming at achieving high overall efficiency for TCES and electricity generation in CSP plants, carbonation would be carried out at high CO2 partial pressure and high temperature (around or above 800 °C), whereas, calcination could be performed at relatively low temperature (~700 °C). As regards the fast phase of the carbonation reaction, the use of fine particles (

The flow properties of five samples of a ceramic powder, characterized by different particle size distributions were measured at ambient temperature and at 500 °C with the High Temperature Annular Shear Cell. A significant increase of powder cohesion was observed at high temperature. A model combining a continuum approach and a particle–particle interaction description was used to correlate the powder tensile strength with the interparticle forces. The dependence of the tensile strength on powder consolidation and temperature is correctly described by the model.

This paper addresses the possibility of carrying out Selective laser sintering (SLS) using powders obtained as mixtures of particles of different size. The beam source used in the experiments was a CO2 laser tube with a nominal power of 40 W. The materials used were model Glass beads and a real ceramic material characterized by irregular shape of the particles. Bimodal distributed powders were generated by mixing samples characterized by different narrow particle size distributions. Single layer sintered specimens were obtained with a laser scanning speed of 50 mm/s and 8 W beam. The sintered specimens were studied by means of microphotography and were characterized in terms of bulk density and tensile strength. Results show that the strength of the sintered specimen is significantly dependent upon the amount of fines in the powder mixture, in spite of the limited effects on the specimen thickness and density. In particular, the highest strength of the sintered material are observed with the highest fraction of fines in the originating powder mixture. In order to estimate the value of the forces between particles of different size produced by the sintering action, the model developed by Liu et al. (2017), based on the Rumpf (1958) approach, was purposely adapted. The application of the model revealed that in our process conditions the connection between large and fines particles is significantly weaker than the force between particles of the same size. The model also indicates that the strength of the sintered materials from mixtures can potentially increase up to values significantly higher than those of the materials sintered starting from the unimodal powder components.

In recent years an increasing numbers of industries (e.g. interested in the manufacture of cosmetics, foods, plastics, catalysts, energetic materials, biomaterials, micro-electromechanical systems have been attracted to fine and ultrafine particles fluidization, particularly thanks to their special chemical and physical properties. It has become gradually more and more important to understand how to control and to process these particles. Although several studies have been carried out on the effect of IPFs on the fluidization, satisfactory understanding of the phenomena that governed the dynamics of the bed has not yet been achieved. Moreover, a direct measure of the particle-particle interactions and their dependency on the particle properties and on the process conditions in a fluid bed reactor is challenging. In the last years many researches started to look at the rheological measurements as a possible way to understand the fluidization behaviour. The aim of the work is to connect flow properties of the bulk solid evaluated with shear cell shear testing and with interparticle interactions in fluidization. In particular, IPFs of fine/ultrafine powders under actual fluidization conditions are obtained by using sound assisted fluidization. With this technique proper fluidization of these cohesive particles is achieved and the results obtained from the experimental tests are analysed in the view of the cluster/subcluster model to calculate IPFs. The obtained values of the IPF intensities were then compared to those evaluated by using direct powder shear testing characterization, analysed with the help of the Rumpf-Molerus approach. An excellent quantitative agreement between the forces found with these two completely independent techniques was found.

La presente relazione riporta la sintesi finale della campagna sperimentale volta alla caratterizzazione della fattibilità del processo di combustione di un fango biologico, essiccato e pellettizzato, fornitoci dalla MM S.p.A. Acque Reflue e Depurazione - Servizio Idrico proveniente dall'impianto di depurazione Milano San Rocco. Particolare attenzione è stata dedicata alla determinazione ed alla caratterizzazione chimico fisica dei macro e micro inquinanti generati dalla combustione dei pellet di fango.

CO2 adsorption on solid sorbents under dynamic conditions is driven by a number of factors, among them textural features (pore volumes, pore size distribution, surface area...), the surface chemistry (polarity, active site, unsaturated coordinative sites...) and the overall active sites accessibility. Depending on the strength of the interaction with CO2 (chemisorption or physisorption), solid sorbents are broadly divided in two groups, although of course a sharp distinction between the two phenomena (in many cases concurrent) is not possible. Starting from CO2 adsorption data acquired in dynamic conditions in a lab-scale fixed-bed reactor or in a fluidized-bed reactor on commercial and ad-hoc synthetized sorbents, a first attempt to correlate adsorption capacities and materials textural properties or relevant adsorption parameters (breakthrough times, ?????) was here reported. Typical conditions of post-combustion CO2 capture were selected. Literature data available on CO2 uptake acquired on solid sorbent under experimental conditions comparable to those considered in this work were also included.

This work is focused on the investigation of the mechanism (isotherm), nature/strength (thermodynamics) and rate (kinetics) of CO2 adsorption on a commercial activated carbon in a sound assisted fluidized bed. Langmuir and Freundlich equations were used to model the CO2 adsorption isotherm in the low pressure region (i.e. typical of a combustion flue gas). The results revealed that Freundlich equation was more accurate for predicting the adsorbed amount than the Langmuir one, which indicates a heterogeneous surface binding. Then, adsorption behaviour was elucidated by energy function such as standard Gibbs free energy, enthalpy and entropy, suggesting the spontaneity and feasibility of adsorption of CO2 by activated carbon, and its exothermic and physical nature. The isosteric heat of adsorption was also evaluated; its decrease with surface loading further indicated the heterogeneity of adsorption sites and also variation in adsorbate-adsorbent interactions. Finally, this study also presented a kinetic analysis of CO2 adsorption, from which CO2 binding on activated carbon was deduced to follow pseudo-first order kinetic.

Enzymatic reactive absorption has been investigated in the last decade as novel strategy to develop environmental friendly technology for post-combustion CO2 capture [1, 2]. The process is based on CO2 absorption in aqueous solutions, the absorption rate is enhanced by the catalytic action of the enzyme carbonic anhydrase (E.C. 4.2.1.1). At temperature lower than 40°C, CO2 hydration reaction is the slowest reaction (10-2 s-1) among those occurring during CO2 reactive absorption in conventional alkaline and amine solvents: hydroxylation rate at pH 10 ranges between 10-1 and 1 s-1 and carbamate formation rate at 3M MEA is about 103 s-1. Carbonic anhydrase is the ubiquitous enzyme devoted to CO2 hydration catalysis in Nature. Depending on enzyme form, about 10-5 M carbonic anhydrase are able to speed up CO2 hydration to bicarbonate so that first order rate constant results between 1 and 103 s-1 [1]. The present contribution reports survey of recent results on the development of CO2 capture processes based on enzymatic reactive absorption from lab to pilot scale. Main investigated issues were: kinetics of thermostable carbonic anhydrase [4], development of solid biocatalyst for industrial application through carbonic anhydrase immobilization [3], proposed reactor configurations for CO2 enzymatic reactive absorption [1, 2], theoretical models CO2 enzymatic reactive absorption unit [5].

CO2 adsorption with solid sorbents is a possible and promising option for post-combustion CO2 capture strategies. With the aim to reach a cost- effective overall process, sorbents are required to be low-cost and versatile in typical post-combustion conditions (CO2 1-15% vol. and atmospheric pressure). In this framework, sorbents derived from re-cycle and/or re-use of wastes used as starting valued material as alternatives for their disposal are particularly welcome. The development of technologies devoted to cost reduction by using lignocellulosic biomasses generated from the industrial processing of agricultural raw materials is a hot research topic. Agroindustry annually generates enormous amounts of residues and their reduction by utilization might mitigate environmental pollution and increase energy savings. Rice husk (RH) is one of the most widely available agricultural waste in rice-producing countries all around the world. RH contains around 75-90 wt.% of organic matter as cellulose, lignin etc. Mineral components are mostly composed of silica (87-97 wt.% of total ashes). A fruitful utilization of RH is helpful to mitigate the disposal problem and to reduce the cost of waste treatment. A possible new life for RH is its re-use for manufacturing new materials as sorbents for CO2 capture. In a view of exploiting the advantages and shortcomings of using a real biomass as starting material for the preparation of sorbent for CO2 capture applications, we prepared different hybrid materials starting from our experience in the production of hybrid carbon- ferric oxide materials containing as carbonaceous support a model and non-porous material (carbon black) [Alfè, PROCI, 2015]. To this aim carbonized RH (cRH) was coated with different amount of ferric oxide particles (FM) as raw FM and as nano disperse FM particles (nFM). A first set of cRH/FM hybrids was produced by varying the amount of cRH from 20 to 80 wt.% following the same approach presented in [Alfè, PROCI, 2015; Gargiulo, App Surf Sci, 2016]. A second set of cRH/nFM hybrids was produced by varying the amount of cRH from 20 to 80 wt.% and by conducting the co-precipitation of nFM in strong alkalinic conditions and in presence of an appropriate surfactant to prevent nFM agglomeration [Utkan, J Colloid Interface Sci, 2011]. The CO2 sorption performances have been evaluated in a lab-scale fixed bed reactor. The materials of the two sets were structural characterized and a careful attention to the modification of cRH in the applied reaction conditions was payed (moderate alkaline medium in the case of FM co-precipitation and strong alkaline medium in the case of nFM coprecipitation). Preliminary data have been acquired and reviewed to understand the effects of composite preparation and morphology on the CO2 sorption capacity.

Among all the CCS strategies, post-combustion capture provides a near-term solution for stationary fossil fuel-fired power plants, eliminating the need for substantial modifications to existing combustion processes and facilities. In this respect, adsorption using solid sorbents has the potential, in terms of energy saving, to complement or replace the current absorption technology. Therefore, the design of highly specific CO2 adsorbents materials is requested. In this framework, great interest is focused on nanomaterials, whose chemico-physical properties can be tuned at the molecular level. As regards the handling of such materials, sound-assisted fluidization is one of the best technological options to improve the gas–solid contact by promoting a smooth fluidization regime. The present work is focused on the CO2 capture by sound-assisted fluidized bed of fine activated carbon. Tests have been performed in a laboratory scale experimental set-up at ambient temperature and pressure, pointing out the effect of CO2 partial pressure, superficial gas velocity, sound intensity and frequency. Effectiveness of CO2 adsorption has been assessed in terms of the moles of CO2 adsorbed per unit mass of adsorbent, the breakthrough time and the fraction of bed utilized at breakpoint. The results show, on one hand, the capability of the sound in enhancing the adsorption process and, on the other hand, confirm that sound assisted fluidization of fine solid sorbents is a valid alternative to the fixed bed technology, which require also an additional previous step of pelletization.

The Ca-Looping (CaL) technology, based on a dual gas-fluidized bed system of CaO/CaCO 3 particles operated at high temperature, is a viable technological process for highly efficient pre-combustion and post-combustion CO 2 capture. In this paper we show a lab-scale experimental study on the carbonation/decarbonation of a fluidized bed of CaO particles at CaL conditions as affected by the application of a high-intensity acoustic field. The results obtained demonstrate that both carbonation and decarbonation are remarkably enhanced for sound intensity levels above 140 dB and frequencies of about 100 Hz. Fine particles (of size smaller than d p ∼ 100 μm) are entrained in the oscillating gas flow induced by an acoustic field of such low frequency, which yields a strong agitation of the bed and improves the gas–solid contact efficiency. On the other hand, an intense convection of gas flow (acoustic streaming) is generated on the surface of larger particles unmovable by the sound wave, which promotes the heat/mass transfer at the gas–solid boundary in this case. Either of these mechanisms, whose relative importance will depend on the average particle size and sound frequency, will contribute to increase the carbonation and decarbonation rates of CaO fluidized beds in the CaL technology.

Recent studies of CO2 sorption on low-cost metal oxides strongly encourage their use as sorbents [Alfè, PROCI, 2015] in CO2 capture and storage (CCS) strategies. Magnetite (Fe3O4, FM) and CO2 interaction proceeds through acid-base interactions involving unsaturated metal and O sites exposed on FM surface. The FM sorption capacity is lowered by the tendency of magnetite particles to agglomerate causing a decrease of the exposed surface area. The dispersion of magnetic particles on carbon-based solid matrices has been proposed to face this limitation. Thanks to their low-cost, high surface area and porosity, carbonized biomasses are good candidates for supporting FM phase. Rice husk (RH) is an agricultural residue abundantly available in rice producing countries, obtained during the milling of paddy (22 wt. % of the weight of unmilled rice is received as husk). It presents a high ash content, which is 92 to 95% silica, highly porosity and a high surface area. RH is a green material that has a great potential for technological applications since it can be converted to different types of fuels and chemical feedstocks through a variety of thermochemical conversion processes. Following the same approach presented in our previous works on the CO2 capture performances of FM supported on a carbon-based reference material (carbon black) [Alfè, PROCI, 2015; Gargiulo, App. Surf. Sci. 2016], the synthesis and characterization of RH/FM composite materials were performed. A set of RH/FM composites were produced by varying the amount of carbonized RH from 20 to 80 wt.% in order to optimize the sorbent properties for CO2 adsorption applications. Preliminary data about the CO2 sorption capacity were also obtained.

CO2 is one of the major greenhouse gases responsible for global warming. To face the problems related to the large amount of CO2 released into the atmosphere, a number of carbon capture and storage (CCS) strategies are formulated [Yang, Environ. Sci., 2008]. Post-combustion capture offers considerable advantages because it prevents the need for substantial modifications of the combustion process and on the technologies usually used [Bhown, Environ. Sci. Technol. 2011]. Metal-organic frameworks (MOFs) are technologically advanced solid sorbents for post-combustion capture strategy [Raganati, CEJ, 2014], combining large surface area, permanent porosity, tunable pore size/functionality, selectivity, ease of handling, renewability for repeated cycles, [Stock, Chem. Rev. 2012]. MOFs are coordination polymers typically synthesized, under mild conditions, by a self-assembly reaction between metal ions (nodes) and organic ligands (linkers). This work focuses on an aluminum-based MOF known as MIL-96 in which aluminum ions are coordinated with benzene tricarboxylic acid linkers [Loiseau, JACS, 2006]. We performed the synthesis of MIL-96 as pure phase and also in presence of growing amounts of carbonaceous material in form of graphene-like layers [Alfè, App. Surf. Sci. 2015]. The pure MIL-96 phase and four MIL96/GL composites were characterized in terms of elemental composition, thermal behavior and porosity. The ability of those materials to act as CO2 sorbents was evaluated on the basis of the breakthrough curves performed in a lab-scale fixed bed microreactor. The evaluation of CO2 capture performances indicated that the composites are better CO2 sorbents compared to the pure MOF. Studies for the comprehension of the effect of the introduction of GL layers on CO2 adsorption capacity are ongoing.

In the last 50 years the CO2 emission from combustion of fossil fuels increased more and more being responsible for climate changes. According to Protocol of Doha the European Union decided 20% reduction of CO2 emission levels of 1990 by 2020. This paper describes and analyzes the overall scenario of greenhouse gases emissions from urban, industrial and agricultural activities in the reference year 2011 of a covenant of 13 small towns located in Valle Caudina (about 50.000 citizens) area and proposes strategies to sustainable energy production by valorization of organic wastes locally produced. Strategies to reduce greenhouse gases emissions were based on improving energy efficiency of public and private buildings through thermal insulation, promotion of car sharing and substation of old and polluting cars, promotion of use of bikes, public education campaign etc. Nevertheless, here we limit the discussion to proposals basically aimed at substituting fossil for renewable fuels thus enhancing local production of energy from biomass in order to exploit agricultural and wooded waste which represent a large heritage of the valley. Among projects proposed one involves the chipping of wooded waste and their use as fuel for heating of school buildings. Others involve collection and use of floricultural waste or animal livestock manure for anaerobic digestion to produce biogas to be transformed into thermal and/or electrical energy.

The aeration and mixing behaviours of two nano-sized powders, Al(2)O(3) (40 nm) and CuO (33 nm), have been investigated in a laboratory scale fluidized bed. The fluidization quality of both powders is very poor without application of acoustic fields. Sound intensities larger than 135 dB and frequencies in the range 100-125 Hz improve their fluidization quality resulting into a homogeneous fluidization regime with high bed expansion. Under the effect of sound, mixing between powders has been qualitatively characterized by the visual observation of the bed and the SEM analysis of captured samples. Under the operating conditions tested, mixing between aggregates of the two powders takes only few minutes. However, mixing also occurs inside aggregates but this process requires larger times, of the order of 80-150 min. (C) 2010 Elsevier B.V. All rights reserved.

CO 2 adsorption with solid sorbents is one of the most promising options for post-combustion CO 2 capture strategies. Typical post-combustion flue-gas conditions are CO 2 1–15% vol. and atmospheric pressure and the performances of solid sorbents under typical flue gas conditions have been poorly investigated. In that condition the CO 2 uptake capacity is influenced primarily by material functionality effects rather than material pore metrics so materials with a distinctive surface chemistry (presence of activated surface atoms or sites) could find applications in adsorption technologies. Hence the sorbent selection became a key point because the materials should be convenient from the economic point of view but versatile in post-combustion conditions. Recent studies of CO 2 adsorption on low-cost iron metal oxide surfaces strongly encourage the possible use of metal oxide as sorbents, but the tendency of magnetite particles to agglomerate causes a lowering of CO 2 uptake capacity. The dispersion of magnetite nanoparticles on carbonaceous matrix appears to be a promising strategy to overcome this shortcoming. This work investigates the adsorption behavior of CO 2 on composite materials prepared coating a low-cost commercial carbon black (CB) with magnetite fine particles. The CO 2 capture capacity of composites produced at different CB load was evaluated on the basis of the breakthrough times measured at atmospheric pressure and room temperature in a lab-scale fixed bed micro-reactor. A CB–FM composite has been selected to verify the possibility of carrying out a two-stage operation and the thermochemical stability in a sound assisted fluidized bed. To this aim the reactor has been firstly operated for CO 2 adsorption and then for regeneration. The effect of multiple cycles of adsorption and desorption steps has been also quantified.

The main results, in the frame of co-gasification in fluidized bed reactor, obtained at IRC/CNR - in the last years are reported. The results confirm that co-gasification is a suitable strategy for end-life plastic waste conversion and this in turn may contribute on the reduction of plastic landfill disposal as well as to realize a plastic sustainable life cycle

The activity, commissioned by the Company TERNA S.A. and performed at the laboratories of the Institute for Research on Combustion, has as its objective the assessment of the quality of a sample of natural gas

This paper describes and analyzes the overall scenario of greenhouse gases emissions from urban, industrial and agricultural activities in the reference year 2011 of a covenant of 13 small towns located in Valle Caudina area (about 50.000 citizens) and proposes, on the base of the emissions inventory data, strategies to reduces emissions by 20-30%. The work was carried out in the context of Piani di Azione per l'Energia Sostenibile (PAES) representing a European movement where local/regional authorities voluntarily commit to increasing energy efficiency and use of renewable energy.

In this work we have tested the fluidized bed desulfurization performance of an activated carbonate sorbent obtained with a limestone pre-treatment/activation technique. This performance was compared with that of the parent untreated limestone particles. The occurrence of particle fragmentation and attrition during the fluidized bed operation was also investigated with a specific test protocol for both limestone and activated carbonate sorbent. Two particle size ranges were tested under typical fluidized bed coal combustion conditions (T = 850°C; SO2 = 1800 ppm). Results showed that the treatment/activation technique was able to preserve after calcination the initial particle size distribution of the parent particles. In addition, high calcium reactivity and final conversion were observed for the activated carbonate particles, leading to a much better SO2 capture capacity per unit mass of sorbent than that obtained with the untreated limestone. Simple economic evaluations suggest that the use of this pre-treated sorbent in place of limestone can involve significant savings for fluidized bed coal combustor operators.

Two different wet sewage sludges have been characterized under fluidized bed combustion conditions with reference to their devolatilization behavior and ash comminution with the aid of different and complementary experimental protocols. Analysis of the devolatilization process allowed to determine the size of fuel particle able to achieve effective lateral spreading of the volatile matter across the cross-section of medium-scale combustors. Primary fragmentation and primary ash particle characterization pointed out the formation of a significant amount of relatively large fragments. The mechanical properties of these fragments have been characterized by means of elutriation/abrasion tests using both quartz and sludge ash beds.

A new concept system is presented for the combined production of heat and electric power. Two renewable energy sources are used, i.e., direct solar (thermodynamic solar) and biomass (indirect solar energy). Biomass combustion is conducted using a fluidized bed combustor. A second source of energy, given by the direct irradiation of the bed with a concentrated solar radiation, is integrated in the same system. A Scheffler mirror is planned to carry out sunlight irradiation of the fluidized bed in a fixed focal point. A Stirling engine, integrated in the fluidized bed, converts heat into electricity. A working prototype, referred to as MEGARIS, has been developed very recently and is presently under test. The proposed paper is mainly devoted to automatic control and load regulation of the MEGARIS prototype. A simple dynamic mathematical model has been developed for the fluidized bed acting at the same time as solid biomass combustor, solar light receiver and heat exchanger toward the Stirling engine. For control and regulation purposes, the bed temperature has been taken as the controlled variable; the process variables acting as disturbances have been identified, e.g., the sunlight power; the main manipulated variable has been considered the solid biomass feed rate; the system parameters that are subject to uncertainty have been identified, e.g., the power dissipated through insulation. The control and regulation strategy relies on a feedback architecture. Different theoretical approaches and sophistication levels have been proposed and tested for the loop controller, i.e., PID, Fuzzy Logic and predicting model-based. Both the dynamic model and the controller algorithms have been developed in Matlab scripts and implemented in Simulink codes. A systematic simulation has been carried out for both the open loop and closed loop system responses to those changes that are realistically expected in the main process variables or in uncertain parameters. In parallel, the dynamical analysis of the mathematical model of the prototype has been carried out with Matcont. The results obtained so far are very encouraging to achieve flexibility and controllability of the MEGARIS prototype.