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A systematic study on the use of noble metals (Pd, Pt, Au) supported on titanate nanotubes (NT-Ti) for selectively producing BTX and p-cymene from waste tire pyrolysis is provided here. All the materials were characterized for chemical, textural and structural properties using a range of analytical techniques. The M/NT-Ti (M: Pd, Pt, or Au) catalysts exhibit low nanoparticle sizes (1.8 Pt ≈ Au > support > non-catalyst. The Py-GC/MS suggest that the catalysts participate in the secondary reactions of dealkylation, dehydrogenation, isomerization, aromatization, and cyclization leading to a higher formation of BTX than the uncatalyzed reaction. Finally, a comprehensive reaction pathway describing the catalytic pyrolysis of WT over Pd/NT-Ti was proposed by studying the catalytic pyrolysis of individual polymers constituting the waste tires, and D, L -Limonene.

The production of renewable chemicals using lignocellulosic biomass has gained significant attention in green chemistry. Among biomass-derived chemicals, secondary amines have emerged as promising intermediates for synthetic applications. Here, we report a systematic study on the reductive amination of phenolics with cyclohexylamine using Pd/C and Rh/C as catalysts. The catalytic tests were performed in batch reactors under different reaction conditions (various: amine concentration (0.1–0.4 mol/L), hydrogen pressure (0–2.5 bar), temperature (80–160 °C), and substituted phenols (phenol, o-cresol, p-cresol, and methoxyphenol)) and using tert-amyl alcohol as a solvent. The experimental observations were consistent with a multi-step mechanism, where hydrogenation of phenol to cyclohexanone is followed by condensation of the ketone with cyclohexylamine to form an imine, which is finally hydrogenated to produce secondary amines. In addition, there was evidence of parallel self-condensation of the cyclohexylamine. The study also supported a limited dehydrogenation capacity of Rh/C, unlike Pd/C, which increases this capacity at higher temperatures generating a higher yield of cyclohexylaniline (up to 15%). The study of the alkylated phenols demonstrated that the nature and propensity of hydrogenation of the phenolic controls their amination. Kinetic analysis revealed reaction orders between 0.4 and 0.7 for H2, indicating its dissociative adsorption. Meanwhile, phenol’s order (between 1–1.8) suggests a single participation of this compound in the hydrogenation step. The order of 0.4 for cyclohexylamine suggests its participation as a surface-abundant species. The apparent activation energies derived from a power law approximation were of 37 kJ/mol and 10 kJ/mol on Pd/C and Rh/C, respectively.

Iron-catalyzed tar decomposition is studied by inspecting changes in catalytic activity and its correlation to the metal oxidation numbers. A carbon-aerogel-supported iron (Fe/CAG) catalyst was used herein to decompose toluene (model tar) at between 500 °C and 700 °C. The catalytic decomposition was studied in a conventional reaction system, and the catalyst was characterized prior to and after the reaction to understand the effect of the structural changes in the catalytic activity. The results demonstrated that the iron oxidation state and coke deposition strongly depend on the reaction temperature. The X-ray diffraction patterns confirmed that at T

Catalytic pyrolysis has been used to upgrading the quality of pyrolytic liquids. Herein, we report a comprehensive study on the catalytic pyrolysis of waste tires using Ni/SiO2 as catalysts. The analyses were carried out by combining thermogravimetry (TGA), TGA interfaced to a Fourier transform infrared spectrometer (TGA–FTIR), and pyrolysis coupled to gas chromatography/mass spectrometer (Py–GC/MS) techniques. During waste tire decomposition, the main functional groups detected in the FTIR were alkenes, aromatics, and heteroatoms-containing groups such as nitrogen, sulfur, and oxygen. Meanwhile, by Py–GC/MS were identified mainly D,L-limonene, isoprene, benzene, toluene, xylenes (BTX), and p-cymene. The Py–GC/MS experiments at three different temperatures (350, 400, and 450 °C) suggested an effect of the catalyst on product distribution. The Ni catalyst promoted cyclization reactions and subsequently aromatization, leading to an improved vapors composition. The use of iso-conversional kinetic models along with master plots allows proposing a multiple-step reaction mechanism, which was well described by the Avrami–Erofeev, Random Scission, and truncated Sestak–Berggren models. The values of activation energies show differences for the catalyzed and uncatalyzed pyrolysis (111.0 kJ mol−1 and 168.4 kJ mol−1), validating the effectivity of Ni/SiO2. Finally, the thermal Biot (> 1) and PyI and PyII numbers (10–3

Extrinsic self-healing of bituminous materials using encapsulated rejuvenators is a hot topic within road materials. Based on a circular economy vision for more sustainable and resilient asphalt pa...

Tar removal from gasification gases is a determinant step to guarantee the operational feasibility of gasification-to-chemicals/energy systems. However, this is a very complex process requiring catalytic materials to proceed under reasonably low temperatures and to convert the tars into fuel gases (i.e., CHx). The use of Fe-based catalysts for application has been reported before, however, there are still unsolved questions related to its stability and interaction with some species of gasification gases. Therefore, we evaluated carbon-supported Fe for the decomposition of tar using simulated gasification gases, and toluene, naphthalene, and benzene as models for tar. The effects of temperature (565 < T < 665 °C) and co-feeding CO on the catalytic activity and stability were inspected at laboratory and bench scales. The activity of catalysts for decomposing tars was in the following order: benzene > toluene e > naphthalene. Moreover, there was evidence validating a reversible elemental step toluene⇔benzene over the Fe surface. The characterization of the spent catalysts evidenced the oxidation of the active phase and the carbon deposition on the surface. The formation of FexOy caused a marked loss of activity. Conversely, the carbides were stable and still active for tar decomposition.

This study aimed to determine an optimal dosage of sunflower oil (i.e., Virgin Cooking Oil, VCO) as a rejuvenator for asphalt self-healing purposes, evaluating its effect on the chemical (carbonyl, and sulfoxide functional groups), physical (penetration, softening point, and viscosity), and rheological (dynamic shear modulus, and phase angle) properties of long-term aged (LTA) bitumen. Five concentrations of sunflower oil (VCO) were used: 1%, 2%, 3%, 4%, and 5% vol. of LTA bitumen. VCO was encapsulated in alginate biopolymer under vibrating jet technology using three biopolymer:oil (B:O) mass ratios: 1:1, 1:5, and 1:9. The physical, thermal, and mechanical properties of the capsules were studied, as well as their effect on the physical properties of dense asphalt mixtures. The main results showed that an optimal VCO content of 4% vol. restored the chemical, physical, and rheological properties of LTA bitumen to a short-term ageing (STA) level. VCO capsules with B:O ratios of 1:5 presented good thermal and mechanical stability, with high encapsulation efficiency. Depending on the B:O ratio, the VCO capsule dosage to rejuvenate LTA bitumen and asphalt mixtures varied between 5.03–15.3% wt. and 0.24–0.74% wt., respectively. Finally, the capsule morphology significantly influenced the bulk density of the asphalt mixtures.

About 25.7 million tons of waste tires (WT) are discarded each year worldwide causing important environmental, and health problems. This waste is difficult to manage and dispose due to its huge rate of generation and its extremely slow biodegradation. Therefore, many efforts are being made to valorise WTs into a series of marketable products under a circular economy framework. In the attempt to convert WT into higher-value products, thermochemical decomposition by pyrolysis has emerged as a promising process. The pyrolysis is a thermochemical transformation (under an oxygen-depleted atmosphere) of the tire´s polymeric constituents: natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR) into three major fractions. These fractions are a gas (10–35%, TPG) which is usually used as a heat source (50 MJ kg⁻¹), a solid consisting mainly of recovered carbon black (12–45%, rCB), and a liquid fraction (35-65%, TPO) containing a complex mixture of organic compounds. Among the high-value compounds that can be found in the TPO are D,L-limonene, isoprene, benzene, toluene, mixed-xylene, ethylbenzene, styrene, p-cymene, and some polycyclic aromatic hydrocarbons. This mixture is commonly used as a diesel substitute and owing to its complex composition it rarely is seen as a source for more valuable products. To overcome such a complexity, and selectively produce specific chemical identities, different types of catalysts have been used. Herein, we provide a dataset from a systematic study about catalytic pyrolysis of WT for selectively producing benzene, toluene, and xylenes (BTX) and p-cymene on noble metals (Pd, Pt, Au) supported on titanate nanotubes (NT-Ti). The comprehensive analysis of this data was recently published, thus, the analytical techniques, experimental conditions and dataset are given in the present paper as a complement to that publication. The reaction was evaluated in an analytical pyrolysis unit consisting in a micropyrolizer coupled to a mass spectrometer (Py-GC/MS) operating at temperatures between 400 and 450 °C in a fast pyrolysis regime (12 s). The effectivity of catalysts was measured in terms of selectivity to monoaromatics as BTX and p-cymene, under non-catalytic and for catalytic pyrolysis conditions. Moreover, the reaction was conducted on individual rubbers (Polyisoprene, Polybutadiene, and Styrene-Butadiene) and DL-limonene, to get deep insights into the transformation behaviour and reaction pathways. Therefore, the reader will find a data-in-brief paper containing some characterizations of the WTs used for the investigation, along with a complete dataset of Py-GC/MS results. Finally, the original files for the interpretation of the MS results are also provided, so that the reader can easily use this information to further expand the study to their own interest (industrial or scientific)., Puede accederse a los datos primarios de este trabajo haciendo clic en "Documentos relacionados"., Centro de Investigación y Desarrollo en Ciencias Aplicadas

This study evaluated the effect of two encapsulation methods (i.e., dropping funnel and syringe pump), two concentrations of the alginate-based encapsulating material (2%, and 3%), and three oils as bitumen rejuvenators (virgin sunflower oil, waste cooking oil, and virgin engine oil) on the morphological, physical, chemical, thermal, and mechanical properties of encapsulated rejuvenators for asphalt self-healing purposes. A general factorial design 2 × 2 × 3 was proposed to design 12 different Ca-alginate capsules. Significant differences on the morphological, physical, and mechanical properties of the capsules were analysed by three-way ANOVA and Tukey HSD Post Hoc analyses. The effect of the type of oil on the self-healing capacity of cracked bitumen samples was also evaluated. The main results showed that the design parameters and their interactions significantly affected the morphological, physical, and mechanical properties of the capsules. Capsules synthesised via syringe pump method, with virgin cooking oil and 2% alginate was the most appropriate for asphalt self-healing purposes since its uniform morphology, encapsulation efficiency up to 80%, thermal degradation below 5% wt., and compressive strength above the reference asphalt compaction load of 10 N. Finally, the healing tests showed that virgin cooking oil can be potentially used as a rejuvenator to promote asphalt crack-healing.

Hydrogels of TEMPO-oxidized nanocellulose were stabilized for dry-jet wet spinning using a shell of cellulose dissolved in 1,5-diazabicyclo[4.3.0]non-5-enium propionate ([DBNH][CO2Et]), a protic ionic liquid (PIL). Coagulation in an acidic water bath resulted in continuous core-shell filaments (CSFs) that were tough and flexible with an average dry (and wet) toughness of similar to 11 (2) MJ.m(-3) and elongation of similar to 9 (14) %. The CSF morphology, chemical composition, thermal stability, crystallinity, and bacterial activity were assessed using scanning electron microscopy with energy-dispersive X-ray spectroscopy, liquid-state nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, pyrolysis gas chromatography-mass spectrometry, wide-angle X-ray scattering, and bacterial cell culturing, respectively. The coaxial wet spinning yields PIL-free systems carrying on the surface the cellulose II polymorph, which not only enhances the toughness of the filaments but facilities their functionalization.

The present study reports on the technical, economic and environmental analysis of small-scale gasification-ICE systems integrated into sawmills in Chile. Two scenarios were considered, (i) a 100 kWe system for self-consumption in a sawmill and (ii) a 1000 kWe system for using residues from different sawmills. The gasification system was technically assessed by a comprehensive mathematical model implemented on Aspen One 10.0, while economics were studied by the Levelized cost of electricity (LCOE) and environmental impacts were quantified by a Life cycle assessment of forestry, sawmills and power plant processes. Results demonstrate that heat recovery is critical for the process economy, which exhibits an LCOE between 0.15 and 0.32 USD/kWh, and a return on investment of 6.4 years. Nevertheless, the gasification system is far for being an economically-feasible alternative for Chile, where electricity price is 0.08–0.10 USD/kWh. In contrast to economic assessment, the implementation of the gasification-ICE power plant would be a promising alternative for decarbonization of the Chilean energy matrix, showing a reduction of 93% of carbon emissions versus actual practices (viz. co-firing process). From the environmental point of view, biomass harvesting and transport are the critical stages during the whole life cycle of energy production, regardless of the scenario.

Defense-related metabolome traits in pine species after infestation by Sirex noctilio are largely unknown, despite, in most cases, trees being overwhelmed. Using LC-MS-based untargeted metabolomics, we revealed the systemic metabolic changes induced by this insect in 14-year-old Pinus radiata trees, the most affected species worldwide. An immediate metabolome alteration was expressed in needles after infestation, including the up-regulation of flavonols, flavan-3-ols, oxyneolignans, auxins, proline, and tryptophan, among others. The flavan-3-ols (catechin and procyanidin B1) suggested a rapidly induced photoprotection mechanism aided by diverting proline as an alternative substrate for respiration to compensate for the progressive chlorosis that degrades photosystems. Meanwhile, glutathione, glutamate, and ascorbate levels significantly dropped in needles, which may indicate the critical oxidative stress that trees had to face since the onset of the infestation. They were not fully replenished after long-term infestation, and redox homeostasis was probably not achieved, compromising tree survival. Nevertheless, a huge auxins overexpression detected in needles throughout the infestation may reflect tolerance against the premature senescence caused by the woodwasp venom. In contrast, the metabolome of wood tissues remained initially unchanged, although it seems to collapse after three months. Overall, the metabolomics strategy adopted in this work evidenced its usefulness in uncovering the fundamental roles of plants' chemical defense that govern interactions with specific stressors.

Purpose This study aims to assess environmentally three different alternatives related to the valorization of Dichrostachys cinerea (L.) Wight & Arm. (marabou), identified as an invasive tree, as a feedstock for cogeneration facilities installed in the sugarcane industry in Cuba. The alternatives are (A-1) Electricity generation from marabou in a conventional back-pressure steam turbine cycle, (A-2) Electricity generation from torrefied marabou in a back-pressure steam turbine cycle, and (A-3) Electricity generation from torrefied marabou using extraction-condensing turbines.Methods SimaPro 9.0.0.35 software was used for the modeling of the inventory, based on different operational parameters. The ReCiPe environmental impact assessment method was used in the hierarchical perspective, assessing 18 impact categories (midpoint), and 3 damage categories (endpoint).Results and discussion The results demonstrated that A-3 shows the lower environmental impacts (Fine Particulate Matter Formation, Terrestrial Acidification, and Water Consumption) as compared to A-2 and A-1. This performance is explained by a lower normalized marabou consumption (1.85 kg marabou/kWh generated), and lower emissions associated with marabou harvesting, transportation, and processing. The cogeneration stage was the main contributor to the environmental burdens in Water Consumption (100% in A-1; 87% in A-2 and A-3). Marine Ecotoxicity was the impact category with better environmental performance due to the substitution of synthetic mineral fertilizers by ashes produced during combustion. The human health damage category reached the higher impacts on the torrefaction subsystem in the A-3 scenario, representing over 94% of the total environmental burden of the process. PM2, and SO2 contributed the most over this damage category, mainly in marabou combustion, causing injuries in respiratory systems by aspiration of organic compounds.Conclusions The use of more efficient technology (extraction-condensing steam turbine), using torrefied marabou as feedstock, compared with the previous alternatives, impacts beneficially on the environment. Thus, a combination of marabou torrefaction with cogeneration facilities in sugarcane industries can be considered as an environmental-friendly technology in the Cuban context. The current study results will help decision-makers implement more sustainable policies in the Cuban energy sector, using marabou as feedstock as an attractive bioenergy route pathway.

Metal catalysts based on Ni, Co, and Pd supported on SiO2 were evaluated in the catalytic pyrolysis of waste tires using pyrolysis experiments coupled to gas chromatography/mass spectrometry (Py–GC/MS) and thermogravimetric analysis coupled with Fourier Transform Infrared spectrometer (TGA–FTIR) techniques. The effect of temperature and the nature of metals on the product distribution and reaction pathways was determined. Catalytic pyrolysis promoted aromatization and cracking reactions at particularly low temperatures ca. 350 °C, leading mainly to the formation of alkenes (isoprene), aromatic terpenes (p-cymene), aliphatic terpenes (d,l-limonene), and other aromatic compounds such as benzene, toluene, and xylenes (BTX). The Pd/SiO2 catalyst was the most selective toward aromatic compounds (around 40 %), owing to its well-known hydrogenation/dehydrogenation capacity, while CC bond cleavage reactions, leading to alkenes, were more favored on the Ni/SiO2 and Co/SiO2 catalysts. In all cases, high selectivity to limonene and isoprene was observed at low temperature. Above 400 °C, no significant differences in product distribution were observed between catalyzed and uncatalyzed pyrolysis. Herein, selectivity toward high-value hydrocarbons (i.e., d , l -limonene, isoprene, BTX, and p-cymene) during the catalytic pyrolysis of waste tires was tuned by the nature of the supported transition metals (i.e., Ni, Co, Pd) and the reaction temperature (e.g., Centro de Investigación y Desarrollo en Ciencias Aplicadas

This study aimed to characterise polynuclear biocapsules containing low-cost rejuvenating agents for asphalt self-healing. Capsules consisted of a biopolymeric matrix of calcium alginate containing cooking oil and mineral oil as rejuvenating agents, being synthesised using ionic gelation through the pumping dripping technique. The physical-chemical properties of the oil-in-biopolymer emulsions and their stability over time were studied. The morphological and thermophysical properties of the biocapsules, as well as the encapsulation efficiency of the rejuvenating agents, were quantified and characterised by microscopic techniques and laboratory tests. Main results showed that emulsions should be used for encapsulation purposes within a period no longer than 3h, reducing the effect of instability phenomena. Besides, the biopolymer-based polynuclear capsules presented uniform size, internal multicavity microstructure resulting in high encapsulation efficiencies and thermal stability at high temperatures, proving that cooking oil and mineral oil can be potentially used as low-cost rejuvenating agents and thermally stable additives for asphalt self-healing purposes.

The CO hydrogenation reaction was studied under methanation conditions (H2/CO >3, 250–300 °C) on Co/SiO2 catalysts with different mean Co nanoparticle size (dp = 4 nm, 13 nm and 33 nm). The catalysts were prepared by incipient wetness impregnation; the cobalt loading and reduction conditions were suitably selected in order to produce catalysts with different dp. Operando FTIR and kinetic measurements provided consistent data for the heat of CO adsorption at low and full coverage. The results confirm the structural sensitivity of the CO hydrogenation reaction on supported cobalt catalysts and demonstrate the energetic heterogeneity of the cobalt surface. A model derived from the Temkin formalism accurately fits the kinetic data and renders the heterogeneity of the cobalt surface by capturing the change in the heat of CO adsorption with the CO coverage. This change is normalized by the heat of CO adsorption at high coverage (ΔQCO/Q1) in order to quantify and compare the heterogeneity of cobalt surfaces. The CO hydrogenation turnover rates are lower on the catalyst with smaller nanoparticles. This surface shows higher heterogeneity and lower apparent activation energy, which is attributed to a larger amount of the more active B5-B sites in this catalyst.

The effects of leaching (25 °C and 1 h) sugarcane trash (SCT) and sugarcane bagasse (SCB) with citric acid (CA) on the yields and quality of fast pyrolysis bio-oils were studied. A comparison was made with commonly used leaching agents such as water or solutions of HCl and H2SO4. The quality of the obtained bio-oils was assessed using a set of analytical techniques including elemental analysis, total acid number (TAN) and water content determinations, combustion calorimetry and gas chromatography-mass spectrometry (GC/MS) analysis. Results from the fast pyrolysis of SCT or SCB pretreated with acids reveal higher yields on raw-feedstock basis (38–45 wt.%) of the organic bio-oil fraction than those from raw and water–leached feedstock, but lower yields of water (7.6–10.2 wt.%) and char (13.1–14.9 wt.%). More than 90% of non-condensable gases were CO and CO2. The most important observations related to the effect of leaching with CA on the chemical composition of the bio-oil are a significant increase of the relative abundance of sugars from 15.1% in raw SCT to 44.7% in CA-pretreated SCT, as well as a decrease in carboxylic acids, ketones, furans and phenols with respect to the raw biomasses. These results were close to those obtained from well-known leaching agents such as HCl and H2SO4. The bio-oil from the pyrolysis of CA–leached SCT and SCB have slightly higher HHVs than those obtained from reference leaching solutions (HCl and H2SO4). In addition, the TAN showed the lowest acidity among all pretreated SCB samples.

A comprehensive study of carbon aerogel-supported nickel (Ni/CAG) in the catalytic fast pyrolysis (CFP) of torrefied Eucalyptus globulus was performed in a micropyrolysis unit (Py-GCMS). Effects of pyrolysis temperatures (450–600 °C), catalyst-to-biomass ratio (1:1 pi 2 adsorption-desorption at 77 K, X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). Regardless the use of catalysts, the pyrolysis vapors produced from torrefied biomass were depleted in carboxylic acids (selectivity 2 -depleted atmosphere, presumably by a synergistic effect between water gas shift and reforming reactions with transalkylation and decarbonylation of phenolics and furanics. It was demonstrated that metal cluster sizes influenced the reaction routes by favoring hydrogenation on metal facets and deoxygenation on step/corners sites.

Sugarcane trash (SCT) and sugarcane bagasse (SCB) are prospective feedstock materials for fast pyrolysis. However, their relatively high inorganic content, especially alkali and alkaline earth metals (AAEMs), affects the quality of the produced bio-oil. This study evaluates the effect of SCT and SCB leaching by citric acid (CA) on the chemical composition of pyrolysis vapors, viz. by applying micro-pyrolysis (Py-GC/MS). Comparison was made between CA and well-known leaching agents including H2SO4, HCl and water. Accordingly, biomass samples were previously leached at different temperatures and leaching times. The results indicate that leaching with either citric acid or well-known inorganic acids causes the yields of levoglucosan in the pyrolysis vapors to increase by 5–8 fold. The mild structural changes in the lignocellulosic matrix, caused by hydrolysis during leaching, demonstrated to be as important for subsequent thermal degradation behavior (and thus increased anhydrosugars production) as the suppression of the intrinsic catalytic effect of the inorganic constituents by their removal during leaching. CA treatment generally favored the reduction in the total production of ketones and furans independently of leaching conditions (temperature, time). Differences in the range of leaching conditions tested (T = 25–50 °C; t = 1–12 h) had only minor influence on the composition of the pyrolysis vapors derived from CA pretreated sugarcane residues.

The effect of leaching with citric acid on the ash fraction removed and the resulting changes in thermal degradation behavior of sugarcane trash (SCT) and sugarcane bagasse (SCB), was studied. A comparison between citric acid and well-known leaching agents including H2SO4, HCl and water, was made considering their effects on chemical, structural and thermal properties of the leached SCT and SCB. Demineralization and potential biomass hydrolysis was evaluated based on proximate and elemental analyses, Fourier transform infrared spectroscopy (FTIR-ATR) and thermogravimetric analysis (TGA). For citric acid and the reference leaching solutions, the mass fraction of ash removed was in a narrow range (between 38.9 and 54.1%) regardless of biomass type and leaching conditions (temperature and time) tested. The nonparametric bifactorial analysis of results revealed that the nature of leaching solution and its interaction with contact time are of major significance when demineralizing both SCT and SCB. Interestingly, no significance of temperature and its interaction with contact time was found. In acid-treated samples, the 1730 cm−1 IR-band was sharpened while the signal at 1600 cm−1 was largely attenuated, which could be attributed to the modification of the xylan fraction and to the substitution of C=O by OH groups. These mild structural changes, caused by hydrolysis, demonstrated to be very important for subsequent thermal degradation. The later was confirmed by the disappearance of the hemicellulose decomposition peak in the derivative thermogravimetric (DTG) curve.

This paper investigates the exergoenvironmental aspects of a Municipal Solid Wastes (MSW)-fueled Gasification Integrated Combined Cycle (WICC). Accordingly, the environmental impacts associated to exergy destruction, total environmental impact, exergoenvironmental factor and the electricity environmental impacts (EEI) are studied. A sensitivity analysis is carried out in order to have a good insight into WICC plant performance, focusing on MSW environmental impacts (0.1–0.9 millipoints (mPts)/kg MSW) and considering only CO2 emissions as pollutant formation. The results show that the largest environmental impacts are associated to gasification and are mainly caused by chemical exergy destruction (44%) and pollutants formation (61%). The highest total environmental impact (Btot) corresponds to the highest MSW impact, due to the impacts produced by the changes in the specific exergy of the streams. Discarding CH4 and CO from pollutants formation, reduced the Btot and EEI by nearly 55%. Furthermore, the calculated EEI values (13.5 mPts/kWh) are lower than that reported for conventional energy systems (i.e. Natural gas: 22–26 mPts/kWh). Therefore, this technology could be a promising alternative for energetic valorization of MSW in the Chilean conditions.

Nickel and iron supported on thermostable cellulose-derived carbon aerogels (CAG), were used for the catalytic fast pyrolysis (CFP) of crude and torrefied Eucalyptus globulus . Pyrolysis vapors produced from torrefied biomass under non-catalytic conditions were reduced by 70% in carboxylic acids with respect to vapors originating from crude biomass, but also were richer in ketones and aromatics. In the case of CFP of both crude and torrefied E.globulus on CAG-supported iron and nickel (Fe/CAG and Ni/CAG), the metallic clusters were activated for ketonization, while Ni 0 provided additional hydrogenation sites, increasing the production of monoaromatics (c.a.18% selectivity), leading to a high acids-to-ketone (ξ A-K = 1.3) and heavy-to-light (ξ H-L = 1.0) ratios. Accordingly, Ni/CAG and Fe/CAG were more effective than HZSM-5 –a traditional cracking catalysts– for upgrading CFP vapors to light compounds. The combination of zeolite acid sites with the oxophilic Ni 0 and Fe 0 allows the deoxygenation of vapors while the ratio of polyaromatics to light aromatics (ξ PAHs ) was reduced by nearly 50%.

The effects of using (NH4)2SO4 as a carbonization promoter for producing cellulose-derived carbon aerogels (CAG) was studied. The effects of pretreatment on the textural, morphological, and chemical properties of pristine cellulose nanofibers (CNF) were analyzed through N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), elemental analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), and Fourier transform infrared spectroscopy (FT-IR). Furthermore, the thermal behaviors of raw CNF and those impregnated with (NH4)2SO4 were investigated by coupling thermogravimetric analysis with mass spectrometry (TGA-MS). The results suggested that the pretreatment did not cause any morphological/structural changes in the nanofibers. However, the presence of (NH4)2SO4 affected their pyrolysis by favoring intermolecular dehydration, thereby reducing the formation of levoglucosan and increasing the carbon yield during pyrolysis. Interestingly, above certain impregnation level, the concentration of sulfate-derived species in the gas phase increased. This phenomenon was attributed to an excess of salt within the fiber structure and on their surfaces. Consequently, the levoglucosan-to-carbon route was inhibited, and the mechanisms of intra- and inter-molecular dehydration, chain scission, and crosslinking reactions were affected, leading to a reduced char yield. The chemical effects of ammonia-based salts is elucidated supported on the interpretation of MS signals and kinetic modeling results.

The fast pyrolysis of waste tires (WTs) is studied by quasi-isothermal thermogravimetric (TGA) analysis, kinetic modelling and an analytical pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS). The TGA demonstrated that the WTs pyrolysis is ruled by devolatilization/condensation and depropagation reactions, up to 482 °C. At higher temperatures, the cyclization and aromatization of primary products take place to form mostly monoaromatics. Py-GC/MS experiments were performed under kinetic regime according to the thermal map established by the ratio between Biots (31.25) and Py-numbers (7.7⋅106). Limonene (51%) and isoprene (20.5%) were the major compounds detected at temperatures below 435 °C, while above 600 °C limonene was converted to mono-aromatics (SBTX = 28.7%). The approach to equilibrium of Diels-Alder reaction demonstrated that there is an equilibrium-ruled behavior between isoprene and limonene, particularly at T > 600 °C. The Ea values calculated by the Starinḱs model ranged from 101.5 to 176.7 kJ/mol, while for model-based kinetics it was 152.7 kJ/kmol. The integration of TGA, kinetic modelling and Py-GC/MS provided insights into pyrolysis reaction mechanism.

The liquid phase amination of the cyclohexanone (CyO) with aniline (PhNH2) was studied on a Pd/C catalyst using NaCO2H as a H-donor. Catalytic tests were performed in batch reactors by varying reactant concentrations (0, 0.1, 0.2 and 0.4 mol/L), the temperature (80–160 °C) and H2-equivalents availability (0, 2 and 4 H2-equivalents with respect to CyO). The results indicate that, the use of NaCO2H barely affect the reactivity (measured as initial reaction rate) while it does influence the selectivity to secondary amines. This effect was ascribed to the limited effectivity of the H2 transfer, which was controlled by the water formed after the condensation of the CyO with the PhNH2, hydrogen solubility in toluene, and the mass transfer from the liquid to the catalyst surface. The experimental observations were consistent with a multi-step mechanism consisting in: a first step of condensation of the ketone and the amine to form an imine, followed by the disproportionation of the imine into secondary amines. The kinetic measurements at initial rate conditions were well interpreted by a Langmuir Hinshelwood (L-H) kinetic model, which suggest that the surface reaction to form the intermediary imine is the rate limiting step (R.L.S).

In this paper, we report on the economic and environmental issues associated with a pyrolysis plant for processing sugarcane residues. The analyses consider four scenarios: (i) raw sugarcane bagasse (SCB), (ii) raw sugarcane trash (SCT) and acid-leached (iii) sugarcane bagasse (L-SCB) and (iv) sugarcane trash (L-SCT). The systems were studied by integrating a comprehensive mathematical model and experimental data. The environmental impact assessment was performed using the Life Cycle Assessment (LCA) methodology, including agriculture and sugar industry stages into the system boundaries. The results demonstrate that the process economy heavily depends on the bio-oil composition, yield, feedstock cost, and leaching conditions. Bio-oil from L-SCT and L-SCB contained more than 30 wt%. levoglucosan, which made it a candidate to produce fermentable sugars or other valuable chemicals instead of being burnt in low-efficiency boilers. The unitary cost of bio-oil produced from L-SCT (0.89 USD/L) and L-SCB (0.75 USD/L) was below that obtained for raw biomass, even when the Total Investment Costs behaved differently. The environmental impacts, expressed in damage categories, associated with L-SCB and L-SCT, were nearly 86% higher than for SCB and SCT. The highest impact could be attributed to the citric acid (CA) production chain, biomass transport, and harvesting operations.

Exergy and exergoeconomics assessment tools were applied to a municipal solid waste (MSW) gasification system integrated with a combined cycle (WICC). The techno-economic feasibility of the system was studied using a typical MSW produced in southern Chile and a combined experimental-modeling approach. Results suggested that gasifier should operate between 850 °C and 950 °C, in order to produce a syngas with the required energy content (LHV>3 MJ/kg) to feed power and steam cycles. Operation at lower temperatures and equivalence ratios, reduced the exergy efficiencies (

Asphalt self-healing by encapsulated rejuvenating agents is considered a revolutionary technology for the autonomic crack-healing of aged asphalt pavements. This paper aims to explore the use of Bio-Oil (BO) obtained from liquefied agricultural biomass waste as a bio-based encapsulated rejuvenating agent for self-healing of bituminous materials. Novel BO capsules were synthesized using two simple dripping methods through dropping funnel and syringe pump devices, where the BO agent was microencapsulated by external ionic gelation in a biopolymer matrix of sodium alginate. Size, surface aspect, and elemental composition of the BO capsules were characterized by optical and scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermal stability and chemical properties of BO capsules and their components were assessed through thermogravimetric analysis (TGA-DTG) and Fourier-Transform Infrared spectroscopy (FTIR-ATR). The mechanical behavior of the capsules was evaluated by compressive and low-load micro-indentation tests. The self-healing efficiency over time of BO as a rejuvenating agent in cracked bitumen samples was quantified by fluorescence microscopy. Main results showed that the BO capsules presented an adequate morphology for the asphalt self-healing application, with good thermal stability and physical-chemical properties. It was also proven that the BO can diffuse in the bitumen reducing the viscosity and consequently self-healing the open microcracks.

This paper reports on the environmental issues associated with the manufacturing of a new insulation material (panel) produced with fibers from Eucalyptus bark. The analyses consider four types of eucalyptus bark panels with different bulk densities (25, 50, 75 and 100 kg/m3). For each type of panel, the environmental impact assessment is performed using Life Cycle Assessment (LCA) methodology and considering system boundaries from cradle to gate. Major environmental impacts were associated to the panel with a density of 100 kg/m3, due to the higher mass required for the same functional unit (R = 1 m2K/W). The panel manufacturing, forest management and biomass transport were the stages with the highest significance, mainly due to: the contribution of the synthetic fiber used for binding the bark-derived fibers, intensive use of agrochemicals in forest management and long traveled distances for biomass transportation. Furthermore, the eucalyptus bark panels with densities of 25 and 50 kg/m3 shown the lower embodied energy and carbon emissions than traditional insulation materials (expanded polyurethane, polystyrene, glass fibers and glass wool). Therefore, it could be an attractive insulation material for a more sustainable building sector.

Biomass gasification is a promising way to obtain &ldquo, green energy&rdquo, but the gas composition makes it unsuitable for use in traditional technologies (i.e., IC engine). Gas purification over nickel and/or iron catalysts is an attractive alternative. Cellulose-based carbon aerogels (CAGs) have shown suitable physical chemical properties for use as catalyst supports. In this work, nickel and iron catalysts are supported on CAG made from cellulose microfibers. Microfibers were impregnated with (NH4)2SO4 to increase the mass yield. Carbonization was evaluated at different heating rates, maximum temperatures, and dwell times to generate CAGs. Resulting chars were characterized by N2 adsorption, X-ray diffraction (XRD), and Raman spectroscopy. The CAG with better properties (specific surface, pore size, thermal resistance) was impregnated with the metal precursor salt via incipient wetness and treated with H2. Catalysts were characterized by transmission electron microscopy (TEM), XRD, N2 adsorption, and inductively coupled plasma optical emission spectrometry (ICP-OES). Ammonia adsorption was studied over CAG and catalysts to estimate the thermodynamic parameters. The impregnation with ((NH4)2SO4 improves thermal resistance of the char obtained from carbonization. The catalysts exhibit higher adsorption capacity than CAG (without metal), indicating chemical interaction between ammonia and metals. The metal-ammonia interaction is stronger on Fe than on Ni catalyst, which is consistent with reported theoretical calculations.

The feasibility of integrating a solid oxide fuel cell (SOFC) technology into the Cuban energy sector is analyzed. In this context, two scenarios for power generation are assessed: the first (existing) combines a bagasse cogeneration unit and diesel combustion engines and for the second (future), diesel engines are replaced by a SOFC feed with ethanol and integrated into the sugar factory. The environmental impact (greenhouse gases), exergy efficiency, and a renewability parameter are considered as indicators for the assessment of the studied scenarios through a multifunctional unit (9.86t/h sugar, 2.195t/h of hydrated ethanol (96% w/w) and 847kWh of electricity) approach. The SOFC scenario shows significant advantages from an environmental point of view, obtaining a reduction of 55% greenhouse emissions and 60% fossil fuel consumption. At the same time, the overall process efficiency (38%) and renewability index (0.93) are higher than for the existing scenario. Furthermore, health impacts and their corresponding external cost related to airborne emissions (primary and secondary pollutant) are estimated applying the Uniform World Model (UWM). In this sense, the results show that the use of a SOFC technology involves a reduction of health impacts in 25.76 YOLL yr-1 (12%) and external costs of 52175 US$ yr-1 (12%). The potentiality of SOFC technology implementation into Cuban energy sector is assessed using a Strengths, Weaknesses, Opportunities and Threats (SWOT) approach. Nowadays, the main threat of implementation of this technology is associated to competitive energy market.

Torrefaction is a thermal pretreatment leading to the improvement of most of the fuel properties of biomass, namely energy density, HHV (higher heating value), grindability and hydrophobicity. The aim of this study is to identify the most feasible temperature to carry out torrefaction of Eucalyptus globulus and nitens , based on chemical evidences associated to the release of volatiles during thermal treatment of biomass. With that end: (i) Devolatilization kinetics, (ii) Effects of temperature and residence time and (iii) volatiles composition during torrefaction of both wood and bark were analyzed. In all cases DTG (derivative thermogravimetric curves) exhibited the typical shape of lignocellulosic materials, with three decomposition phases and two reaction zones. Values of activation energies for hemicellulose decomposition, were in agreement with those reported in the literature (121–170 kJ/mol). Carboxylic acids, water and phenolic compounds showed two peaks, which were associated to torrefaction (below 310 °C) and pyrolysis (310–410 °C) respectively. The most feasible temperatures for torrefaction were estimated as a function of these peaks, and it ranged between 295 °C and 310 °C for all samples. Main volatile species at the torrefaction peaks were distributed as Water > Acetic Acid > CO 2 > Others, while Levoglucosan formation was marginal, due to the catalytic effect of inorganics.

The use of wood as feedstock for the production of energy and chemicals is a strategy used by both developing and developed countries because it increases the sustainability of their energy infrastructure. Torrefaction of forest resources for co-firing and densification of biomass energy is among the most prominent alternatives. This study is focused on technical aspects of torrefaction technology by analyzing both energy and exergy changes through a comprehensive physico-chemical model (Aspen One v8.6 software) of a plant operating in mild (250 °C) and severe (280 °C) regimes. The main wood species in Chilean plantations, Eucalyptus globulus and Pinus radiata , were processed in a lab-scale apparatus to obtain the data for model calibration. We found that xylan composition in hemicelluloses has a considerable effect on global thermal efficiency, volatiles energy content, energy density, and exergy yield of torrefied product. The highest efficiency (96%) is obtained for Eucalyptus at 250 °C when moisture in the feedstock is ≤ 20%. Combustion of volatile products (torgas) for drying does not result in substantial technical benefits for the overall process; however, their post-combustion does lead to lower exergy losses.

A SOFC (solid oxide fuel cell) system integrated with an ethanol steam reforming unit is evaluated using exergoeconomic analysis. The exergy destruction cost, total production cost, relative cost difference, exergoeconomic factor and thermoeconomic cost of electricity are studied. The TCOE (thermoeconomic cost of electricity) is compared with electricity cost from similar processes and fuels. A sensitivity analysis has been carried out in order to have a good insight into SOFC power plant performance, focusing on ethanol steam reformer temperature (823

In this article, the environmental impacts associated to cofiring coal with forest biomass for electricity production in Chile are analyzed for: (i) untreated pine pellets and (ii) torrefied-pretreated pine pellets. Results show that energy production from cofiring coal/untreated wood pellets or coal/torrefied pellets, featured significant reductions in environmental impacts, as compared with pure coal plants. Indeed, reductions in acidification (28–26%), abiotic depletion (15–7%), eutrophication potential (15–12%), global warming potential (16–6%), photochemical oxidation (28–23%), human toxicity (17–15%), terrestrial ecotoxicity (12–9%), and marine aquatic ecotoxicity (17–15%) were obtained when untreated or treated pellets were used as a substitute for coal. Moreover, the environmental profile of torrefied pine evidenced its low impact per energy unit, in most of the studied categories except for eutrophication and marine aquatic ecotoxicity, for which the harvesting, logistic chain and torrefaction processes were the most important contributors.

The objective of this study was to develop a comprehensive mathematical model of bagasse gasification integrated with a gas turbine combined cycle (BIGCC). The model uses a quasi-equilibrium approach to evaluate the thermodynamic performance of the plant, considering both first and the second law of thermodynamics. The influence of pressure ratio in the compressor (1:4

The health external costs of the electricity generation alternatives associated to a sugar ethanol factory are investigated. Two scenarios of power generation facilities have been analyzed in this study: the first scenario (existing) combines a bagasse cogeneration unit with a diesel combustion engines and the second scenario (future) the diesel engines are substituted by a solid oxide fuel cell (SOFC) fed with ethanol and integrated into the sugar factory. The health impacts referred as Years of Life Loss (YOLL) for the two proposed scenarios are estimated applying the Uniform World Model (UWM). Monetary values of damage costs related to human health per kW h of generated electricity are determined, as well as its influence on the total production cost. Therefore, the results of the external costs evaluation, shows that the use of a SOFC technology involves a reduction of health impacts in 25.76 YOLL year−1 (12%) and external costs of 52,175 US$ year−1 (12%), as well as a reduction of the electricity cost of 0.05 US$ cent per kW h in comparison with the existing scenario (bagasse cogeneration and diesel combustion engines). The internalization of this external cost would increase the production cost and the electricity price by more than 30% and 10%, respectively.