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In the current study, sugarcane bagasse-derived biochar catalysts were synthesized by doping with metal-free heteroatoms including nitrogen, phosphorus, oxygen, and boron and their efficacy was tested for catalytic co-pyrolysis of walnut shells (WS) and palm oil fatty acid distillate (PFAD) using Py-GC/MS. The biochar catalysts' properties and their effectiveness on co-pyrolytic bio-oil (overall product distribution, selectivity towards aliphatic and aromatic hydrocarbons, and carbon number ranges) were extensively examined. Among the various catalysts considered, boron-doped biochar (BCB) demonstrated effective performance due to an improved surface area, porosity, and acidity and resulted in a significantly increased hydrocarbon yield, particularly in the gasoline and diesel range, and preference for aromatic over aliphatic hydrocarbons. The optimum bio-oil quality was achieved at a feedstock-to-catalyst ratio of 2:1 and a pyrolysis temperature of 750 °C, with a hydrocarbon yield of 90.8 % and aromatic hydrocarbon selectivity of 63.5 %. Overall, the study underscores the role of BCB in fostering deoxygenation, decarboxylation, and aromatic selectivity via thermal and catalytic pathways, highlighting the potential of non-metallic doped biochars for bio-oil upgrading. [Display omitted] • Catalytic co-pyrolysis of walnut shells (WS) and PFAD was examined. • Pioneering use of PFAD for enhanced bio-oil production via co-pyrolysis. • First study to use boron-doped biochar (BCB) as an effective co-pyrolysis catalyst. • BCB significantly increased hydrocarbon yield and aromatic selectivity. • Feedstock to catalyst ratio of 2:1 provided highest aromatic hydrocarbon yield. [ABSTRACT FROM AUTHOR]

The interesterification of rapeseed oil was performed in a batch reactor using for the first time low surface area massive tin(II) oxide as heterogeneous catalyst and methyl acetate as acyl acceptor. The effect of reaction temperature, methyl acetate to oil molar ratio and catalyst loading on the performances of the process were investigated. Yields in fatty acid methyl esters (FAMEs) and triacetin (TA) up to 90% and 70% respectively, were achieved after 4 h of reaction time at 483 K in the presence of 0.69 mol of SnO per mole of rapeseed oil using a methyl acetate to oil molar ratio of 40. Quite interestingly, the catalyst performances improved when water was added to the reactions system. Moreover the same catalyst sample was used three consecutive times without observing any depletion of the catalytic activity. Collected results indicate that SnO is a promising heterogeneous catalyst for the interesterification of triglycerides with methyl acetate. [ABSTRACT FROM AUTHOR]

Nanostructured Li-delafossite based catalysts were prepared via solution combustion synthesis (SCS) method and investigated under realistic conditions as catalysts for the carbon gasification in a reducing environment. LiFeO 2 catalyst was selected as the most promising candidate for the soot gasification catalyst on a soot trap application close coupled to a biogas autothermal reforming (ATR) reactor for syngas post-treatment process. LiFeO 2 was coated on a wall-flow monolith filter (15/20 μm mean pore size and 46% porosity) via solution combustion deposition (SCD) method and the coated filters' performance was evaluated during the soot particles loading. The pressure drop across the filters was very low (< 8 mbar), showing that the method of coating on the filters was successfully applied. [ABSTRACT FROM AUTHOR]

The replacement of inert gas by CO 2 in pyrolysis has piqued a great deal of interest in recent years due to its numerous positive effects on end products. The reactive nature of CO 2 at higher pyrolysis temperatures (above 700 °C) during pyrolysis improves pyrolytic gas production (H 2 , CO, and CH 4) by increasing thermal cracking of tar, inhibiting secondary char formation, and enhancing char gasification, thereby reducing char yield. The existing review articles focus on the impact of CO 2 on tar and gaseous products during pyrolysis, with little information on its impact on biochar production and properties via slow pyrolysis of various organic wastes. Therefore, it is worthwhile to investigate the effect of CO 2 on biochar production during slow pyrolysis for industrial purposes, because CO 2 from flue gas can be used as the pyrolysis gas environment, which can ultimately improve biochar production in terms of economic viability, environmental impact, and modified properties. The goal of this review is to conduct a thorough investigation of the effect of CO 2 atmosphere on slow pyrolysis performance (400–700 °C), with a particular emphasis on biochar yield and properties for environmental and agricultural applications in comparison to inert atmosphere by highlighting the existing challenges and future opportunities. [Display omitted] • Impact of CO 2 on biochar production via slow pyrolysis is deeply investigated. • Agro-environmental properties of biochar is reviewed. • CO 2 increases biochar yield within the temperature 400 and 600 °C. • CO 2 greatly improves biochar's surface area, carbon and aromatic contents. • CO 2 could be used to alter the agro-environmental properties of biochars. [ABSTRACT FROM AUTHOR]

The [Ru(bpy) 3 ] 2+ /persulfate photosystem is the most common dye/sacrificial reagent pair used to study the catalyzed water oxidation half-reaction. Recently, we developed a bubbling reactor along with its modelling, and we used it with the aforementioned photosystem to measure the actual rate of reaction ( R O 2 ) over time. In the present work, the same method is employed to investigate the kinetics of the reaction occurring through several steps, i.e. not only water oxidation, but also parasitic reactions due to chemical instability of the intermediate [Ru(bpy) 3 ] 3+ species, which degrade over time finally decreasing the reaction rate. O 2 evolution as catalyzed by Mn 2 O 3 is examined at three irradiance conditions, and for three different catalyst contents. Qualitatively, whereas the increase of catalyst amount yields the expected increase of O 2 production and evolution rate, the increase in irradiance enhances the degradation processes, thus giving a “paradoxical” effect of decreasing the chemical yields. Chemical kinetics are applied, and predictions are compared to experimental data derived from bubbling-reactor. The development of the kinetic model imposing steady state condition on transient species yields as expression of R O 2 a simple linear combination of two exponentials. It is found that the main activity indicators obtained from the bubbling reactor tests can be related in an expression that is independent of the amount catalytic sites, i.e. the ratio between the O 2 evolution rate and the total amount of O 2 evolved during the reaction. Results show that the ratio between the kinetic constants of the desired ( i.e. O 2 formation) and undesired path ( i.e. dye degradation) decreases at increasing irradiance, evidencing how the role of parasitic reactions, far from being negligible, tends to be overwhelming. [ABSTRACT FROM AUTHOR]

Hydrothermal liquefaction is a promising technology for producing renewable advanced biofuels. However, some weaknesses could undermine its large-scale application, such as the significant carbon loss in the aqueous phase (AP) and the necessity of biocrude upgrading. In order to deal with these challenges, in this work the techno-economic feasibility of coupling hydrothermal liquefaction (HTL) with aqueous phase reforming (APR) was evaluated. APR is a catalytic process able to convert water-dissolved oxygenates into a hydrogen-rich gas that can be used for biocrude upgrading. Two cases were proposed, based on different lignocellulosic feedstocks: corn stover (CS) and lignin-rich stream (LRS) from cellulosic ethanol production. HTL-APR plants operating with the same mass flow (3.6 t/h) at 10 wt% solid loading were herein evaluated, resulting in an input size of 20 MW (LRS) and 16.5 MW (CS). Based on experimental and literature data, the mass and energy balances were performed; subsequently, the main equipment was designed; finally, the capital and operating costs were evaluated. The analysis showed that the minimum selling prices for the biofuel (0% internal rate of return) were 1.23 (LRS) and 1.27 €/kg (CS). The heat exchangers accounted for most of the fixed capital investment, while electricity and feedstock had the highest impact on the operating costs. The implementation of APR was particularly profitable with CS, as it produced 107% of the hydrogen required for biocrude upgrading. In this case, APR was able to significantly reduce the H 2 production cost (1.5 €/kg) making it a competitive technology compared to conventional electrolysis. [Display omitted] • A conceptual design and TEA of an HTL-APR integrated plant are performed. • APR produced the H 2 required for the corn stover HTL-derived biocrude upgrade. • Minimum biofuel selling prices are 1.23–1.27 €/kg depending on the feed. • Heat exchangers, feedstock and electricity account for 38–49% of production costs. • H 2 production cost by APR is 77% lower than by electrolysis using corn stover. [ABSTRACT FROM AUTHOR]

The effects of using a 30% by volume blend of a renewable fuel, called Farnesane, and fossil diesel in a small Euro 5 displacement passenger car diesel engine have been evaluated in this paper. Farnesane is a 15-carbon long molecule that can be obtained from the fermentation of biomass-derived sugars (such as sugar cane, amidaceous and cellulosic crops), which are first fermented to Farnesene and then hydrogenated to Farnesane. Farnesane has similar chemical and physical properties to diesel fuel, as far as its viscosity and density are concerned. Its higher Lower Heating Value (LHV) and cetane number mean that the biofuel has better combustion properties, and the lack of aromatics and sulfur could contribute to a decrease in smoke and particulate matter emissions. Tests were carried out on a small displacement Euro5 automotive diesel engine for passenger car applications. The impact that the Farnesane blend could have on engine performance was first evaluated at full load. The effects of the use of the Farnesane blend on engine emissions and fuel consumption were then evaluated at seven different part load operating points, considered representative of the New European Driving Cycle. Other experimental investigations have been carried out to fully exploit the benefits that could be obtained by adjusting the Exhaust Gas Recirculation (EGR) rates in order to take into account the different Soot–NO x and CO–NO x biofuel blend trade-offs. When the engine was fueled with the Farnesane blend in diesel at full load operating conditions, without any modifications of the ECU calibration, brake torque output levels that were comparable with the reference diesel could be observed over almost the entire speed range. At part load operating conditions, which are representative of the New European Driving Cycle, no significant variations in fuel consumption were found on a mass basis, for the same fuel conversion efficiency and CO 2 emissions for the Farnesane blend compared to the diesel. The specific CO and HC emissions were reduced significantly for the biofuel blend at low and medium loads, while only modest or even insignificant variations were registered at higher loads. The NO x emissions with the biofuel blend were generally comparable with those of the reference diesel fuel, while a noticeable reduction in smoke level was generally observed for medium and high load operating conditions. Finally, the Soot–NO x and CO–NO x trade-off, obtained from EGR sweeps, has highlighted the possibility of obtaining some further emission benefits through a better exploitation of the biofuel characteristics by means of a more extensive ECU recalibration. [ABSTRACT FROM AUTHOR]

Abstract: This study focuses on the valorization of biomass wastes in the Piedmont Region, in Italy, with the aim of producing synthetic liquid fuels. On the basis of a territorial survey, the selected fractions from the separate collection of municipal solid wastes (organic fraction, pruning residues and wood refuses) and, to a lesser extent, the residues of the agro-industry, were considered potentially important, due to their abundance and availability throughout the year. Dedicated arborous cultivations, evaluated on the basis of the land that is currently cultivated, also showed a great potential. The sum of the potential recoverable energy from these three categories reaches 35.99×106 GJ/year, i.e. 6.79% of the total final energy consumption of the Piedmont Region. The target of this valorization is here the conversion of these low energy density biomasses into valuable liquid fuels. The direct liquefaction technology was chosen due to its flexibility towards the feed and the possibility of working with wet substrates, these being typical constraints which are difficult to be overcome in the other thermo-chemical processes. In the direct liquefaction process, a pulp of organic material, with a water content ranging from 50% to 90%, is fed to a reactor at around 330°C and 180bar, with a residence time of 4–10min, according to the biomass pulp composition. The resulting bio-oil can be fed to the upgrading section of a refinery, in order to reach standard fuel-grade specifications, which allows it to be blended with currently sold transportation fuels, or it could be used as a source of valuable chemicals in an alternative scenario. A 50ktons/year plant (based on the dry biomass content) was considered, and the balance of plant was sized in order to estimate the energy requirements of the plant and the bio-oil yield. A very convenient configuration was designed, and a bio-oil net production of 37.1wt% was reached (referring to the dry matter of the biomass), which takes into account all the fuel needs of the plant. The specific power consumption was equal to 0.258kWh/kgOil, which corresponds to a ratio between the output and input energy of 35.8 (excluding the biomass lower calorific value). Finally, it should be mentioned that this target was obtained using simple and economic equipment, thus responding to the need to devise a process which could be profitable, even at a medium scale, for local applications. [Copyright &y& Elsevier]

Abstract: Thermo-Electric (TE) power generation is an attractive method for the direct conversion of thermal energy into electrical one. Both the TE material properties and the power generator architecture play a fundamental role in the achievement of high energy conversion efficiencies. The paper focuses on the TE module architecture design, as well as on the sub-components manufacturing and assembly. Segmented TE power generators, characterized by a counter-current arrangement of the hot and cold gaseous streams, and a catalytic combustion chamber to ignite an air/fuel mixture, were designed and manufactured (SiC monolith heat exchangers, catalysts and supports for the combustion chamber, system housing). As TE materials, commercial Bismuth Telluride cells were adopted. Pd/NiCrO4 and Pt/Al2O3 catalysts were investigated to ignite H2, CH4 and H2/CH4 mixtures, at different gas flow rates and fuel concentrations. The results led to the design of a TE generator architecture providing flexible electrical loads through a modular assembly, with an improved thermal management which enhanced the energy conversion efficiency. [Copyright &y& Elsevier]

Abstract: The numerous benefits offered by diesel engines, compared to gasoline ones, are balanced by a drawback of increasing concern, namely soot emissions. Nowadays, soot emissions can be reduced by physically trapping the particles within on-board diesel particulate filters (DPF). The filter gets progressively loaded by filtering the soot laden flue gases, thus causing an increasing pressure drop, until regeneration takes place. The aim of this work is to develop a fully predictive three-dimensional mathematical model able to accurately describe the soot deposition process into the filter, the consequent gradual modification of the properties of the filter itself (i.e. permeability and porosity), the formation of a soot filtration cake, and the final regeneration step. The commercial computational fluid dynamics (CFD) code Fluent 6.2.16, based on a finite-volume numerical scheme, is used to simulate the gas and particulate flow fields in the DPF, whereas particle filtration sub-models and regeneration kinetics are implemented through user-defined-subroutines (UDS). Model predictions highlight uneven soot deposition profiles in the first steps of the filtration process; however, the very high resistance to the gas flow of the readily formed cake layer determines the evolution into an almost constant layer of soot particles. The ignition of the loaded soot was simulated under different operating conditions, and two regeneration strategies were investigated: a “mild regeneration” at low temperature and oxygen concentration, that operated a spatially homogeneous ignition of the deposited soot, and a “fast regeneration”, with an uneven soot combustion along the axial coordinate of the filter, due to strong temperature gradients inside the filter itself. These findings are supported by comparison and validation with experimental data. [Copyright &y& Elsevier]

Power-to-gas is a pathway for the storage of intermittent renewable energy in a chemical form; energy surpluses can be exploited to produce hydrogen (via electrolysis) that can then react with carbon dioxide to produce synthetic methane by using catalytic cooled reactors. Methanation unit has been designed and optimized, defining the number of involved reactors, the number of parallel tubes for each reactor and the staged CO 2 injection to moderate the maximum temperature throughout the reactors. The produced synthetic natural gas (SNG) must have a methane content at least equal to 95 mol.-%, achieved by involving a series of 3 cooled reactors. Dynamic behavior of the as-designed system has been investigated for two cases that can occur when a power-to-gas system is operated intermittently: start-up from reactor hot standby and system operated at partial load. Methanation system requires about 130 s to reach the targeted methane content when it is started up from hot standby. In order to broaden the system rangeability (the minimum percentage of full load), different CO 2 staged injection should be carried out: part of carbon dioxide bypasses first and second reactor and it is directly conveyed to the third one. [Display omitted] • Design of CO 2 methanation unit based on fixed-bed cooled reactors. • Dynamic behavior: start up after hot standby and partial load operation. • Synthetic natural gas quality is achieved after about 130 s from start up. • Carbon dioxide staging should be modified to widen the rangeability (45–100%). [ABSTRACT FROM AUTHOR]

• Oscillations in the N 2 O decomposition on Cu-ZSM-5 depend on the nature of Cu species. • Distribution among different Cu sites is affected by the catalyst preparation method. • The activity basically depends on Cu and Al contents, regardless the preparation method. • Abundance of isolated exchanged Cu sites confers activity but not oscillatory behaviour. • Oscillations occur over oligomeric Cu x O y species with extra-lattice oxygen. A set of Cu-ZSM-5 samples (Si/Al = 25) was synthesized by wetness impregnation, aqueous phase ion exchange and solid-state ion exchange, SSIE. Copper(II) acetate was used as precursor during both wetness impregnation and aqueous phase ion exchange to prepare excessively-exchanged samples (i.e. Cu/Al > 1), whereas SSIE was carried out by sublimating copper(I) chloride. Additionally, a Cu-ZSM-5 sample with extremely low Al content (Si/Al = 500) was prepared by impregnation. The samples were tested in the catalytic decomposition of N 2 O, with the aim of studying possible effects of the preparation technique on the isothermal oscillatory behavior of the reaction rate in a series of tests carried out by varying both the temperature and the residence time. The SSIE sample led to a non-oscillating system, whereas the highest Cu content samples prepared by the two aqueous procedures exhibited clear oscillations of the reaction rate. The Cu-ZSM-5 with Si/Al = 500 was quite inactive, but, surprisingly, gave rise to oscillations of both unconverted N 2 O and produced O 2 concentrations at the reactor outlet. A combined IR spectroscopy and H 2 -TPR study showed the role of oligomeric Cu x O y species with extra-lattice oxygen close to the Al atoms on the observed oscillations. Such species are much more abundant in the samples prepared by either impregnation or ion-exchange, when Cu/Al > 1. In contrast, the sample prepared by SSIE resulted to be rich in Cu+ isolated species, active for the reaction, but not inducing oscillation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of CO 2 atmosphere on biochar production and properties was studied. • Compared to inert N 2 , CO 2 significantly affects the pyrolysis products. • CO 2 promotes biochar yields (400–600 °C) for all feedstocks. • Surface area and porosity of biochar can be improved using CO 2 in pyrolysis. • CO 2 biochar contained higher C, lower O/C and O/H ratios. Slow pyrolysis, a widely recognized thermochemical technique, is employed to produce biochar usually under inert atmospheres. Recently, there is a growing interest in utilizing CO 2 as a carrier gas during pyrolysis as an alternative to inert atmospheres, aiming to modify the resulting pyrolytic products and make them suitable for different applications. This study investigated and compared the impact of CO 2 atmosphere with N 2 on pyrolysis of food waste, rice husk, and grape tree branches waste via slow pyrolysis at temperatures of 400, 500, and 600 °C at 5 and 15 °C/min for 1 h, to evaluate biochar production and its properties. The results demonstrate that CO 2 atmosphere increased the biochar yield for all feedstocks and significantly influenced the physicochemical properties of biochar. Compared to N 2 , CO 2 -derived biochar exhibited less volatile matter, higher carbon content, lower O/H and O/C molar ratios and enhanced textural properties. This study highlighted the potential of utilizing CO 2 for biochar production and tailoring biochar properties for specific applications and the findings contribute to the establishment of sustainable and efficient waste management systems and the production of value-added biochar products. [ABSTRACT FROM AUTHOR]