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Rare earth elements (REEs) are strategic materials widely used in different applications from Information and Communication Technologies (ICT) to catalysis, which are expected to grow more in the future. In order to reduce the impact of market price and reduce the environmental effect from soil extraction, recovery/purification strategies should be exploited. This paper presents a combined acid-leaching/oxalate precipitation process to recover lanthanum from spent FCC catalyst using nitric acid. Preferred to hydrochloric and sulphuric acid (preliminary assessed), HNO3 showed a good capability to completely leach lanthanum. The combination with an oxalate precipitation step allowed demonstrating that a highly pure (&gt, 98% w/w) lanthanum solid can be recovered, with a neglectable amount of poisoning metals (Ni, V) contained into the spent catalyst. This could open a reliable industrial perspective to recover and purify REE in the view of a sustainable recycling strategy.

Biomass gasification for energy purposes has several advantages, such as the mitigation of global warming and national energy independency. In the present work, the data from an innovative and intensified steam/oxygen biomass gasification process, integrating a gas filtration step directly inside the reactor, are presented. The produced gas at the outlet of the 1 MWth gasification pilot plant was analysed in terms of its main gaseous products (hydrogen, carbon monoxide, carbon dioxide, and methane) and contaminants. Experimental test sets were carried out at 0.25–0.28 Equivalence Ratio (ER), 0.4–0.5 Steam/Biomass (S/B), and 780–850 °C gasification temperature. Almond shells were selected as biomass feedstock and supplied to the reactor at approximately 120 and 150 kgdry/h. Based on the collected data, the in-vessel filtration system showed a dust removal efficiency higher than 99%-wt. A gas yield of 1.2 Nm3dry/kgdaf and a producer gas with a dry composition of 27–33%v H2, 23–29%v CO, 31–36%v CO2, 9–11%v CH4, and light hydrocarbons lower than 1%v were also observed. Correspondingly, a Low Heating Value (LHV) of 10.3–10.9 MJ/Nm3dry and a cold gas efficiency (CGE) up to 75% were estimated. Overall, the collected data allowed for the assessment of the preliminary performances of the intensified gasification process and provided the data to validate a simulative model developed through Aspen Plus software.

The production of DME via one-pot CO2 hydrogenation is a strategic way of recycling CO2 with the production of a high-value added product. This work aims to investigate the effect of the main zeolite features, e.g. structure or acidity, on the activity, selectivity and stability of the catalyst for DME production via both methanol dehydration and one-pot CO2 hydrogenation. Several zeolites (i.e. FER and MFI) were synthesized and deeply characterized with XRD, B.E.T, NH3-TPD and FTIR. Obtained crystals were used as catalysts for methanol dehydration as well as for one-pot CO2-to-DME process. Obtained results allow giving new insights about the role of the interaction between metals and acid sites for an efficient DME production via one-pot CO2 hydrogenation. In particular, zeolite acidity plays a crucial role in methanol dehydration step and Lewis acid sites seems to be more active than Brønsted sites. Furthermore, metal/acid proximity plays are a key factor in one-pot CO2 hydrogenation; in fact, the catalytic performances of multifunctional catalytic bed improve by increasing the metal/acid sites proximity. The findings of this research allow to highlight the main factors to be taken into account in terms of design and optimization of new catalytic systems for DME synthesis.

Production of energy or chemicals from biomass and several waste substrates appears a concrete strategy for replacing fossil fuels and reducing carbon dioxide emissions in the atmosphere. In particular, methanol from biomass or bio-waste is considered a reliable energy vector and key intermediate for industrial chemistry. Currently, methanol is industrially produced via syngas conversion using natural gas as the main feedstock. Bio-methane produced via anaerobic digestion (AD) of Organic Fraction Municipal Solid Wastes (OFMSW) may be used as an alternative to natural gas for production of syngas with optimal composition via commercialized reforming processes. In this work, a techno-environmental assessment for methanol production from biogas is presented and discussed. In particular, three case studies were assessed to minimize the environmental impact of bio-methanol production.

The intermittent nature of renewable resources requires for most applications the development of efficient and cost-effective technologies for steady supply of electrical energy. The storage of energy in the form of hydrogen chemically bound within organic molecules (rather than physically as compressed gas or cooled liquid) represents an alternative approach that is attracting great research interest. Compared to other liquid organic hydrogen carriers (LOHCs), dimethyl ether (DME) appears to have the largest potential impact on society, especially if inserted in technological chains of CO2 sequestration and utilization, so to determine an effective mitigation of environmental issues, without any net effect on the carbon footprint. Specifically, the steps of H2 storage and H2 release can take place in two coupled chemical processes, constituted by the exothermic synthesis of DME via CO2 hydrogenation and the endothermic steam reforming of DME, respectively. Herein, the latest advances in the development of heterogeneous bifunctional and hybrid catalysts for the direct hydrogenation of CO2 to DME are thoroughly reviewed, with special emphasis on thermodynamics, catalyst design and process feasibility. Despite many aspects behind the mechanism of DME synthesis from H2-CO2 streams are still to be uncovered, the recent progress in the research on H2 release by DME steam reforming is increasing the interest for effectively closing this binary H2 loop, in view of future green deals and sustainable research developments.

This paper addresses the study of a pyro-gasification plant designed, built, and operated to recover inert metals from different types of solid waste. Experimental tests were carried out using pulper as the solid waste. However, while a reliable composition analysis of the produced syngas was carried out, a precise composition evaluation of the pulper used during the experimental activities was not performed and the related data were characterized by unacceptable uncertainty. Therefore, with the aim of reliably characterizing the plant operation, a thermochemical model of the gasification process was setup to simulate the equilibrium operation of the plant and a vector optimization methodology was used to calibrate the numerical model. Then, a decision-making problem was solved to identify the most suitable optimal solution between those belonging to the Pareto optimal front, thus obtaining reliable composition data for the adopted pulper waste. In particular, four different identification criteria were applied for the selection of small subset of solutions over the 3138 dominant solutions found. Among them, the solution (i.e., set of calibration parameters) that minimizes the experimental-numerical difference between the lower heating value of the produced syngas seemed to provide the most reliable approximation of the real plant operation. Finally, a possible plant configuration is proposed for the energetic valorization of the pulper waste and its overall conversion process efficiency is estimated.

In this study, a new configuration where syngas produced by downdraft gasifier is feed directly in an externally fired air turbine is discussed. Attention was posed towards the critical component of this configuration: the heat exchanger. To achieve acceptable electrical efficiencies, high temperature of the air at the inlet turbine section was imposed. A code for heat exchanger design was built by using Matlab, while the geometrical optimization was performed by using modeFRONTIER by imposing a multi-objective function to maximize the overall heat transfer coefficient and minimize both costs and pressure drops across the equipment. İ 2018 The Authors. Published by Elsevier Ltd.

Commercial buildings or shopping malls are characterized by large thermal and electrical energy consumptions with high variability of energy demand. Therefore, there is a large interest to explore novel renewable energy generation systems for these applications. A novel flexible configuration of biomass-fired CHP system with organic Rankine cycle (ORC) is here proposed and applied to the case study of food retail buildings in the UK. The proposed configuration adopts a molten salt (MS) circuit to transfer heat from the biomass furnace to the ORC plant. A thermal Energy Storage (TES) is proposed to improve the flexible operation of the plant and reduce the size of the biomass boiler. Molten salts have been preferred to thermal oil as they have no fire risks and low environmental impact and can be used as medium for a Two Tank TES with a “direct heating” scheme. The plant has been analysed using real input data from a biomass boiler installation, conversion efficiency and heat demand from the store. The model is informed by hourly energy costs and electricity feed in tariff in order to define optimal size and operation of the bottoming ORC for the specific case study of large commercial energy end user in the UK. The results show that the use of thermal storage in a biomass-fired ORC plant can improve the boiler efficiency and reduce the biomass consumption in thermal-load following operating mode and increase the investment profitability.

The production of DME from CO2 hydrogenation is a way of recycling CO2 and it requires the use of a hybrid multifunctional catalyst to efficiently catalyze the two consecutive reaction paths of methanol synthesis and methanol dehydration directly in one single step. The aim of this work is to investigate the utilization of zeolite-based catalysts for dimethyl ether synthesis by assessing the role of catalyst features in both methanol dehydration and one-pot CO2 hydrogenation. Obtained results, discussed in terms of turnover frequency reveal that FER-type zeolite prepared with Si/Al=10 exhibits the best performances during vapor-phase methanol dehydration whilst the efficiency of CO2-to-DME process strongly depends on the way in which metallic and acidic materials are coupled. Single grain prepared via gel-oxalate precipitation of CuZnZr over zeolite crystals exhibit the best performances in terms of CO2 conversion and DME productivity.

An innovative 1000 kWth pilot plant based on a bubbling fluidized bed gasifier with internal recirculation was operated in experimental campaigns of biomass gasification. The evaluations were focused on the gasifier performances and quality of the product gas. To this aim, tests were carried out at atmospheric pressure using almond shells as a feedstock and three defined gasification mediums (i.e. steam/O2 mixture, 35wt.% and 50wt.% O2 enriched air); process temperature was in the range 820-880 °C. The result assessment allowed to evaluate the system flexibility to the gasifying agent and acquire data on the gas producible with this specific configuration. Based on the dry compositions, LHVs in the range 5.9-6.7 MJ/Nm3 dry, 6.3-8.4 MJ/Nm3 dry and 10.9-11.7 MJ/Nm3 dry were respectively calculated for the three product gases. Correspondingly, an increase in the cold gas efficiency from 0.5 up to 0.7 was also estimated. Concerning the contaminant loads, in the case of the tests related to steam/O2 biomass gasification, particle and tar contents were found in the range 6-10 g/Nm3 dry and 12-18 g/Nm3 dry, respectively, while H2S, HCl and NH3 were at concentrations below 100 ppms (v). © 2015 Elsevier B.V. All rights reserved.

A hybrid system based on lignocellulosic biomass gasification and syngas fermentation represents a second-generation biorefinery approach that is currently in the development phase. Lignocellulosic biomass can be gasified to produce syngas, which is a gas mixture consisting mainly of H2, CO, and CO2. The major challenge of biomass gasification is the syngas’s final quality. Consequently, the development of effective syngas clean-up technologies has gained increased interest in recent years. Furthermore, the bioconversion of syngas components has been intensively studied using acetogenic bacteria and their Wood–Ljungdahl pathway to produce, among others, acetate, ethanol, butyrate, butanol, caproate, hexanol, 2,3-butanediol, and lactate. Nowadays, syngas fermentation appears to be a promising alternative for producing commodity chemicals in comparison to fossil-based processes. Research studies on syngas fermentation have been focused on process design and optimization, investigating the medium composition, operating parameters, and bioreactor design. Moreover, metabolic engineering efforts have been made to develop genetically modified strains with improved production. In 2018, for the first time, a syngas fermentation pilot plant from biomass gasification was built by LanzaTech Inc. in cooperation with Aemetis, Inc. Future research will focus on coupling syngas fermentation with additional bioprocesses and/or on identifying new non-acetogenic microorganisms to produce high-value chemicals beyond acetate and ethanol.

This paper presents a numerical study of the influence of piston shape and injector geometry on combustion and emissions characteristics of a direct-injection spark-ignition engine fueled by syngas (50% by volume of hydrogen, 50% by volume of carbon monoxide) under low/medium load conditions. Three different piston cup geometries namely: High-clearance Combustion Cup (HCC), Low-clearance Combustion Cup (LCC) and Omega Combustion Cup (OCC) have been considered with a compression ratio of 14. An axial full-cone gas jet injector has been considered together with a hollow-cone gas jet injector with several included half-angles, i.e. 30°, 45°, 52.5°and 60°. Computational fluid dynamics modelling has been performed to simulate the combustion process. The results indicate that, in terms of performance, OCC shape is favorable, even if OCC generates relatively higher NOx than the other two configurations. A further analysis has been performed by simulating an engine with OCC piston shape and an included half-angle of injection of 30°, by varying the Start Of Injection (SOI). The results show that the flame propagation velocity reduces as the SOI advances, since the fuel distribution becomes more homogeneous approaching to a premixed case. However, the flame speed reduction is partially balanced by the disappearance of very lean regions thanks to fuel convection and diffusion. İ 2018 The Authors. Published by Elsevier Ltd.

In this paper a small Organic Rankine Cycle (ORC) plant was tested under different operating conditions and by using refrigerants (R245fa) as working fluids. In particular, attention was posed towards the scroll expander of the power plant in order to identify experimental parameters to use in its predictive semi-empirical model. Experimental results obtained by imposing different operating conditions at the expander inlet section (i.e. temperature, pressure, mass flow rate) and different temperature at the condensation section, were used to validate the mathematical model. An in-house code (MatLab/Scilab based) using CoolProp library for the accurate evaluation of fluid properties, was optimized by using a genetic algorithm implemented in modeFrontier software. Thus, the validated model was used in predictive mode to evaluate the machine performances. İ 2018 The Authors. Published by Elsevier Ltd.

This review paper analyses the potential environmental impacts and economic viability of producing biofuel from lignocellulosic biomass resources in various countries of the world. In many developed and developing countries, lignocellulosic biomass is a significant feedstock for bioenergy used in industrial sector for power generation but the fact remains that the detail study on current status of lignocellulosic utilization for bioenergy industry is still estimated and partial. In this context, the present study focuses its efforts to have country based database able to provide a detail and comprehensive information on country specific agricultural policies, residue production and their utilization in different energy sectors. Much more information will have to be gathered on the use and availability of residues, and also, taking into consideration the strong need for R&D on lignocellulosic resources based biofuel production, a comprehensive survey of innovative technologies based on both thermochemical and biochemical processes, able to convert lignocellulosic biomass resources into green biofuel, is discussed.

This paper provides a multi-objective optimization of a hybrid organic Rankine plant for solar and low-grade energy sources. In this plant, water, with a mass flow rate of 1 kg/s at a temperature of 90 °C, preheats the working fluid. The objective of this work is to search for solutions with the highest first and second law efficiencies of the plant and the lowest LEC (levelized energy cost). The design parameters are i) the working fluid, ii) the evaporating and condensing pressure, iii) the maximum temperature of the collector thermal fluid and iv) a parameter representative of the temperature profiles in the heat exchangers. A NSGAII (non-dominated sorting genetic algorithm) has been used. The Pareto front solutions provide Cyclopropane, R143a and R32 as working fluids. The lowest LEC (0.114 $/kWh) and the highest first law efficiency (9.65%) are achieved by using Cyclopropane, with a power output greater than 100 kW. The highest second law efficiency (44%) is obtained by employing R143a, with a low contribution of the solar source and a power output greater than 10 kW. Finally, R32 solutions have comparable performance with respect to R143a solutions. © 2015 Elsevier Ltd.

The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed.

The aim of the paper is to provide thermodynamic evaluations for the production of synthetic natural gas from biomasses in order to determine parameters such as purity and productivity obtained with different configurations process. Analysis results showed that, fixed biomethane productivity, with a single stage of methanation, the use of a water gas shift reactor (WGS) prior to the methanation stage, may contribute to increase of purity in methane, although modest, increasing from 65% to 80 vol.% The final effect is the increase of the heating value of SNG from 23 to 26 MJ/Nm3. Numerical results showed that with a single stage methanation for SNG production, in isothermal conditions, it is possible to obtain a productivity of about 0.30 Nm3biomethane/Nm3syngas with a purity of 80 vol.% but with different complications for the process, such as introduction of WGS stage and/or double CO2 adsorption stage. Other evaluations are proposed in the paper in order to improve the performance of the process, such as the use of isothermal reactor although more difficult to manage compared to the pseudo adiabatic configuration plant. Using isothermal configuration it is possible to have higher conversion levels with smaller dimensions plant and therefore it may be an alternative to conventional systems at the end to create demo as driving force for technological development. © 2014 Elsevier Ltd. All rights reserved.

Yttrium is a strategical material for its several usages in a wide range of industrial production. For this reason, improving the recovery of Yttrium has become a crucial focus for international research. In this scientific activity, the utilization of two extractants, 2-ethylhexyl-mono 2-ethylhexyl ester phosphonic acid (P-507) and sec-octylphenoxy acetic acid (CA-12), working in a synergistic extracting system, has been tested. A series of trials have been carried out to optimize the experimental conditions in order to separate yttrium from a mix of heavy rare earths in chloride media. Tests with different relative concentrations of extractants and a phase modifier (TPB, trybutyl phosphate), with different presaponification rate, have been performed to evaluate the behavior of the synergistic system. Results are very promising to recover and separate yttrium with a high purity. © 2017, The Minerals, Metals & Materials Society.

The solvent extraction technique is the only industrial way used to separate and purificate yttrium from other rare earths. In order to improve this process several extractants have been tested during last years. In this work, the behavior of sec-octylphenoxy acetic acid (CA-12) in Yttrium recovery from high concentrated heavy rare earth mixture was investigated. Sodium hydroxide solution was used in order to presaponify organic phase composed by CA-12 and Tributyl phosphate (TBP) diluted in kerosene. In the investigated condition, TBP confirmed its role of phase modifier not significantly altering the extraction behavior of CA-12. The CA-12-TBP system showed a high affinity in extraction for lighter rare earths such as Sm, Eu, and Gd, leaving yttrium in aqueous phase. Using a feed concentration (∑ [RE]) of 1M, organic mixture is capable to extract around the 70% of metals in a single extraction test showing this extraction sequence Y < Lu < Yb < Tm < Er < Ho < Dy < Tb < Gd < Eu < Sm. Moreover for [CA-12] = 1.79 M and [RE] = 2M the instability of extraction system occurs. © 2017, The Minerals, Metals & Materials Society.

In this work the effect of acidity on catalytic performances of zeolitic catalysts with FER structure in methanol dehydration reaction for DME production is presented. Synthesis condition are tuned in order to obtain a Si/Al ratio in the range of 7-47. NH3-TPD and FT-IR measurements show that aluminum content affect both aluminum incorporation and both strength and distribution of acid sites. Catalytic evaluation suggest that acidity affect methanol conversion while all catalysts exhibit a very high selectivity toward DME suggesting FER structure as a reliable catalyst for DME production. © 2017 American Scientific Publishers All rights reserved.

Aim of the paper is the analysis of experimental data from digestate from buffalo sewage gasification carried out at high pressure, close water critical condition. Experiments were performed in a semi-continuous reactor, by loading the biomass, continuously feeding the pressurised water and removing the gas product from the reaction vessel. At a fixed value of temperature (310 °C), two pressure levels were investigated across the water critical pressure (110 bar and 320 bar). According to the expectation, from the treatment of this type of biomass a liquid fraction, containing some components that can be used as chemicals for the "green industries", was obtained. Aldehydes and carboxylic acids were the main product obtained and the liquid phase composition was revealed to be sensitive to the pressure level, since a more concentrated product was obtained at lower pressure level. In addition, a reaction pathways is proposed coherently to the observed evolution of the liquid phase composition. © 2014 Elsevier Ltd. All rights reserved.

The stringent regulations on the reduction of both pollutant emissions and dependence from crude oil have increased the interest toward alternative energy resources. Transport and energy production sectors are strongly involved in the pollutions net environmental balance and, at the same time, their primary energy requirements are significant. In this scenario, several efforts are carried out to identify new solutions. In the last two decades, in the automotive industry, the use of several alternative fuels for internal combustion engine applications has been investigated. Specifically, this work focuses on syngas and its use in spark ignition (SI) engines. First, a comprehensive analysis of the syngas combustion process has been carried out and accurate laminar flame speed correlations are proposed to characterize the fuel oxidation. Then, these correlations have been implemented in a CFD model to simulate a CFR engine combustion process. Different H2/CO-air mixtures (fuel molar ratio ranging from 50:50 to 100:0 of H2:CO) at different engine operating conditions (compression ratio from 6:1 to 10:1 and fuel equivalence ratio from 0.6 to 0.8) have been considered and the results have been compared with available experimental data. A good agreement has been observed in all conditions, in terms of pressure trace, heat release and other parameters that are useful to characterize the combustion process in SI engines, i.e. burn duration, ignition lag and rapid burn angle. © 2014 Elsevier Ltd.

The paper reports on gasification of almond shells with water at high pressure (above critical value) and temperature. The experimental set up was a semi-continuous reactor, an innovative configuration allowing to continuously remove the gas product from the reaction vessel. The adoption of pressure conditions well above water critical value (30 MPa) and relatively low temperature (300 C) confirmed suitable reaction pathways for biomass conversion with high efficiency leading to a liquid phase rich of some interesting compounds (HMF, furfural). In order to increase the process performances, sodium hydroxide was added as promoter of the gasification reactions. According to an already proposed reaction scheme, results confirmed a positive impact of the additional compound to the liquid yield and quality, while the gaseous phase was enriched in carbon dioxide. © 2013 Elsevier Ltd. All rights reserved.

This article provides the dataset of operating conditions of a hybrid organic Rankine plant generated by the optimization procedure employed in the research article “A genetic optimization of a hybrid organic Rankine plant for solar and low-grade energy sources” (Scardigno et al., 2015) [1]. The methodology used to obtain the data is described. The operating conditions are subdivided into two separate groups: feasible and unfeasible solutions. In both groups, the values of the design variables are given. Besides, the subset of feasible solutions is described in details, by providing the thermodynamic and economic performances, the temperatures at some characteristic sections of the thermodynamic cycle, the net power, the absorbed powers and the area of the heat exchange surfaces. Keywords: Organic Rankine cycle, Low-grade energy, Solar energy, Thermo-economic analysis

The pretreatment step has a key role in the enzymatic conversion of lignocellulosic biomass to bioethanol. Steam pulping of biomass has long been recognized as being effective in producing high biomass fractionation. In this step, the preliminary impregnation of biomass with acid catalysts, including SO2, has been shown to further improve the hydrolytic effect and increase the digestibility of the fibers by enzymes. This work focused on developing an experimental setup for the SO2 impregnation, enabling accurate control of the process variables. The final purpose was the assessment of a method to minimize the quantity of SO2 used, and that could be applicable to continuous operations. Aspen chips were impregnated with the acid catalyst at room temperature in a stainless steel batch reactor, and the influence of the biomass humidity and contact time on SO2 uptake was explored. After the catalyst adsorption, biomass was fed into the steam explosion batch reactor and steamed at 205 °C for 3 and 10 min to obt...

We investigated ethanol production from mixed sugar syrups. Hydrolysates were prepared from enzymatic saccharification of steam-pretreated aspen chips. Syrups containing 45 g/L of glucose and 12 g/L of xylose were detoxified through two ion-exchange resins and then fermented with Pichia stipitis and Saccharomyces cerevisiae immobilized in Ca-alginate gel beads. Combinations of different gel fractions in the fermentation volume, amount of yeast cells, and ratios of P. stipitis vs S. cerevisiae within each bead were compared. In the best conditions, by using a total beads volume corresponding to 25% of the working volume, we obtained a yield of 0.39 g(ethanol)/g(initial sugars). This amount of gel entrapped an initial cell concentration of 6 x 1012cells/L with ratio of S. cerevisiae/P. stipitis of 0.25 g/g. Modified stirred-tank reactors were obtained either by adding marbles or by inserting a perforated metal cylinder, which reduced considerably the rupture of beads while visibly improving oxygenation of the medium.

Water desalination technologies and their possible coupling with solar energy have been evaluated. The topic is of particular interest, especially for countries located within the Southern Mediterranean belt, generally characterized with vast arid and isolated areas having practically no access to electric power from the national grid. Economic factors being one of the main barriers to diffusion of solar devices so far, an attempt has been made to estimate the water production cost for two different seawater desalination systems: reverse osmosis and multiple effect, powered by a solar thermal and a photovoltaic field, respectively. The results obtained for plants of capacity varying between 500 and 5000 m 3 /d have been compared to results concerning a conventional desalination system. In addition, the influences of various parameters, such as depreciation factor, economic incentives, PV modules cost and oil price, have also been considered.

The results obtained from efficiency tests conducted on a flat plate solar collector, according to the ISO 9806/1 test procedure, have been used to determine the uncertainty in the curve fitting parameters. The said standard, though requiring certain levels of accuracy in the measuring process, doesnot provide any method to determine the uncertainty of the efficiency curve parameters. The methodology used in the present paper (not provided by the ISO standard) allows solving the above mentioned problem and evaluating not only the parameters and their uncertainties but also the reliability of the test procedure and its goodness toward fitness. In order to evaluate the effects of measurement errors on the values of the uncertainty in estimated parameters, a sensitivity analysis has also been conducted. Strong dependence of some uncertainties, involving a larger accuracy level in the estimation of the measured parameters, is a clear indication of the present investigations.

This paper investigates the production of ethanol from steam pretreated aspen. The optimal conditions for both the pretreatment and ethanol production were determined. In the former step the parameters investigated were temperature (180−220 °C) and residence time (2−6 min). The most effective combination was 214 °C and 6 min. The exploded substrates were detoxified in three ways, washing with water at 65 °C proving to be the most effective. The substrate was then converted into ethanol via simultaneous saccharification and fermentation. Influences of the reactor type (shaken flasks and stirred bioreactors) and process parameters (solid-to-liquid ratio, enzyme loading, and stirrer speed) have been investigated. The highest ethanol yield obtained from solid-to-liquid ratios of 0.20 g/g was 85% in shaken flasks and 79% in helical stirred bioreactors. In the former case, the ethanol concentration in the broth was 47 g/L. The fermentation unit returns a solid residue with a calorific value of 5612 kcal/kg. The...

Anaerobic Digestion (AD) is a biological process that takes place naturally when bacteria break down organic matter in environments with or without oxygen. Controlled anaerobic digestion of organic waste in enclosed landfill will generate methane. Almost any organic material can be processed with AD, including waste paper and cardboard (of a grade that is too low to recycle because of food contamination), grass clippings, leftover food, industrial effluents, sewage and animal waste. AD produces biogas which is comprised of around 60% methane (CH4) and 40% carbon dioxide (CO2). This biogas can be used to generate heat or electricity and/or can be used as a vehicular fuel. If the intended use is for power generation the biogas must be scrubbed to remove a number of impurities. After conditioning the biogas can be used for onsite power generation, to heat homes or can be added to the national natural gas grid. In recent years several research groups have shown the possibility of upgrading the biogas for biomethane production [1]. This study will show the feasibility of integrating anaerobic digestion plant with onsite polymeric membrane purification system for conditioned biomethane production. © 2012 Elsevier Ltd. All rights reserved.

Fuel grade bioethanol can be produced from a number of lignocellulosic biomass sources. In the present paper the enzymatic hydrolysis of giant reed (Arundo donax) at high biomass loadings up to 20% (w/v) was investigated. Two pretreatment technologies were used: one step steam explosion (SE) with and without acid catalyst and the novel pilot process from Chemtex consisting in a two steps pretreatment. The results of the biomass composition after different pretreatment conditions along with the corresponding enzymatic hydrolizability at low solids loading, indicated that the best pretreatments were the acid catalyzed steam explosion (ACSE) at 200 °C and the Chemtex process in which the SE step was carried out at 206 for 4. min. Various process configurations, including biomass and enzymes fed-batch, were investigated to avoid excessive viscosities and increase the cellulose conversion. Novel enzymatic preparations from Novozymes, Cellic™ Ctec1 and Cellic™ Ctec2, were used for the biomass saccharification. Concerning the analysis of the factors that limited the hydrolysis yields at high DM content, some evidences indicated that product inhibition by xylooligomers could have an important role. The highest solids loading investigated in the present paper was 21%. Under these conditions and by using an enzymes loading of 0.28. g Ctec2/g glucan, an overall sugars concentration of 91. g/L (glucose. +. xylose) can be obtained after 48. h from ACSE at 200 °C. © 2012 Elsevier Ltd.

The paper show the techno economical indications for the upgrading process started from biogas with the scope to produce biomethane for the grid injection and delivered to households and industry or alternatively, it can be used as a fuel for CNG-vehicles. The present work give the numerical simulation with a commercial polymeric membrane, PEEK-SEP™ hollow fiber membranes of the PoroGen Corporation, a US based company that specializes in industrial separation process. The membrane, for the numerical simulation, was fueled with methane, carbon dioxide, hydrogen and nitrogen with a composition similar to the real biogas derived from anaerobic digestion of the organic waste. This study will show the feasibility of integrating anaerobic digestion plant with on site polymeric membrane purification system for conditioned biomethane production. © 2012 Elsevier Ltd. All rights reserved.

Three solid catalysts have been tested in the transesterification of fried oils: CaO, SrO, K 3PO 4. For CaO and SrO the different efficiency, between their use as powder or granules, has been examined. Another investigated aspect has been the catalytic activity at different catalyst loadings and recycles. At the end granules have been employed in a catalytic bed reactor, comparing results with batch systems. Results have shown that using catalyst as granule does not affect the yields after 3 h of reaction. The use of the catalytic bed reactor has given the possibility to perform the transesterification maintaining the catalyst separated from the reactants, without loss of efficiency; in fact the comparison between trials in batch reactor and in catalytic bed system has not shown differences in yields. After 3 h of reaction, at 65°C, 5 wt% of catalyst, we have had the following FAME yields: 92% for CaO, 86% for SrO, 78% for K 3PO 4. The transesterification reaction has shown a sensitive influence respect to K 3PO 4 granules amount used; in fact the yield has reached the 85% using 10 wt% of catalyst. The reutilization of the catalyst, without regeneration, has shown a loss of efficiency of about 10-20% in decreasing yield. © 2011 Elsevier B.V. All rights reserved.

Biomass pretreatement is a key and energy-consuming step for lignocellulosic ethanol production; it is largely responsible for the energy efficiency and economic sustainability of the process. A new approach to biomass pretreatment for the lignocellulosic bioethanol chain could be mild torrefaction. Among other effects, biomass torrefaction improves the grindability of fibrous materials, thus reducing energy demand for grinding the feedstock before hydrolysis, and opens the biomass structure, making this more accessible to enzymes for hydrolysis. The aim of the preliminary experiments carried out was to achieve a first understanding of the possibility to combine torrefaction and hydrolysis for lignocellulosic bioethanol processes, and to evaluate it in terms of sugar and ethanol yields. In addition, the possibility of hydrolyzing the torrefied biomass has not yet been proven. Biomass from olive pruning has been torrefied at different conditions, namely 180–280°C for 60–120 min, grinded and then used as substrate in hydrolysis experiments. The bioconversion has been carried out at flask scale using a mixture of cellulosolytic, hemicellulosolitic, β-glucosidase enzymes, and a commercial strain of Saccharomyces cerevisiae. The experiments demonstrated that torrefied biomass can be enzymatically hydrolyzed and fermented into ethanol, with yields comparable with grinded untreated biomass and saving electrical energy. The comparison between the bioconversion yields achieved using only raw grinded biomass or torrefied and grinded biomass highlighted that: (1) mild torrefaction conditions limit sugar degradation to 5–10%; and (2) torrefied biomass does not lead to enzymatic and fermentation inhibition. Energy consumption for ethanol production has been preliminary estimated, and three different pretreatment steps, i.e., raw biomass grinding, biomass-torrefaction grinding, and steam explosion were compared. Based on preliminary results, steam explosion still has a significant advantage compared to the other two process chains.

The MOFs materials containing copper, zinc or both metals together combined with benzenetricarboxilate linkers have been prepared in solvothermal process and characterized. The products were tested as catalysts for low temperature oxidation of cyclohexene. They showed considerable activity and selectivity which depended markedly on kind of metal contributing in the structure. The samples containing copper and zinc together are more active than that with the only copper, whereas the latter one shows higher selectivity to cyclohexenone.

This work is based on the data collected during trials of a continuous steam explosion (SE) plant, with a treatment capacity of about 350 kg/h, including the biomass fractionation section. The energy and water consumption, equipment cost, and manpower needed to run this plant have been used as the base case for a techno-economic evaluation of productive plants. Three processing plant configurations have been considered: (I) SE pretreatment only; (II) SE followed by the hemicellulose extraction; (III) SE followed by the sequential hemicellulose and lignin extractions. The biomass treatment cost has been evaluated as a function of the plant scale. For each configuration, variable and fixed cost breakdown has been detailed in the case of a 50,000 t/y plant.