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Biomass is a highly versatile renewable resource for decarbonizing energy systems. Gasification is a promising conversion technology that can transform biomass into multiple energy carriers to produce heat, electricity, biofuels, or chemicals. At present, identifying the best gasification route for a given biomass relies on trial and error, which involves time-consuming experimentation that, given the wide range of biomass feedstocks available, slows down the deployment of the technology. Here, we use a supervised non-parametric machine-learning method, Gaussian process regression (GPR), that provides robust predictions when working with small datasets, to develop a model to find the optimal application of a particular biomass in gasification processes. Leave-one-out cross-validation (LOOCV) is used to validate the model's predictive performance. Our model can select the suitable gasification pathway from the characteristics of the biomass, and also identify the optimal operating conditions for a selected application of the produced gas. In addition, with this model, we can obtain insights into the relationships between biomass properties and gasification results, leading to a better understanding of the process. A relevant aspect of this work is that these results rely on a relatively small dataset, representative of those typically collected by research groups using different types of gasifiers worldwide. This study opens the path for future integration of such data, which would allow addressing the complexity of biomass and conversion process simultaneously. With this work, we aim to increase the flexibility of biomass gasification processes and promote the development of bioenergy technologies, considered crucial in the energy transition context.

Pine cone leaves (PCL) and pine kernel shells (PKS), abundant by-products of the Spanish food industry, were selected as precursors for activated carbons (ACs) to adsorb CO2 selectively at industrial post-combustion capture conditions. The goal was to maximize the development of narrow microporosity in the final carbons to boost the CO2 adsorption capacity. We have designed kinetics and equilibrium of adsorption experiments with CO2/H2O/N2 on a selected AC derived from PCL in a thermogravimetric analyzer (TGA) at 50 °C and three partial pressures of CO2 to prove the suitability to capture CO2 from industrial off-gases. When humid flue gas streams were tested, competitive adsorption of CO2 and H2O occurred; however, the difference in the uptake rates favored CO2 adsorption in the early stages. The joint CO2 + H2O uptake was around 2 mmol g−1 at 50 °C in humid conditions, where CO2 reached the equilibrium uptake at the corresponding partial pressure for 15 and 32 vol% CO2 in the feed stream. Moreover, the dynamic performance was addressed by cyclic adsorption–desorption experiments representing different industrial post-combustion capture scenarios in a lab-scale fixed-bed rig. The selected AC showed a stable performance in adsorption-regeneration cycles and very remarkable CO2 capture capacity under dry conditions (up to 1.08 mmol g−1 at 50 ˚C for 30 vol% CO2). Kinetics analysis also supported the faster adsorption of CO2 under cement flue gas conditions.

Adsorption using bio-based adsorbents has been pointed out as an economical and environmentally benign technology for CO₂ gas separation and storage. A bio-based adsorbent can be fabricated from low-cost worldwide available biomass feedstock and bio-wastes from different industries (e.g., dairy manure, forestry, agriculture). As a result, it is a carbon rich material of hydrophobic nature, activated to gain high porosity development, and requires mild regeneration conditions. However, large-scale deployment of bio-based adsorption processes remains challenging. Our group has been intensively developing biomass-based adsorbents in conjunction with the design of tailored CO₂ adsorption-based cyclic processes for the envisioned application. Herein, key concepts on adsorption technology, biomass waste management, and different activation techniques for biomass-based adsorbent precursors are discussed. This review addresses the most relevant studies in the literature, from lab experimentation on a milligram scale (volumetric and gravimetric tests) to dynamic tests in bench or large-scale cyclic adsorption processes (i.e., pressure swing adsorption, temperature swing adsorption, vacuum swing adsorption). Therefore, the main target is to give a holistic view of the industrial applications where CO₂ separations with these materials are more suitable. Finally, concluding remarks and future perspectives of bio-based adsorbents in carbon capture are presented. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

Renewable clean H2 has a very promising potential for the decarbonization of energy systems. Sorption enhanced steam reforming (SESR) is a novel process that combines the steam reforming reaction and the simultaneous CO2 removal by a solid sorbent, such as CaO, which significantly enhances hydrogen generation, enabling high-purity H2 production. The CO2 sorption reaction (carbonation) is exothermic, but the sorbent regeneration by calcination is highly endothermic, which requires extra energy. Biogas is one of the available carbon-neutral renewable H2 production sources. It can be especially relevant for the energy integration of the SESR process since, due to the exothermic sorption reaction, the CO2 contained in the biogas provides extra heat to the system, which can help to balance the energy requirements of the process. This work studies different process configurations for the energy integration of the SESR process of biogas for high-purity renewable H2 production: (1) SESR with sorbent regeneration using a portion of the produced H2 (SESR+REG_H2), (2) SESR with sorbent regeneration using biogas (SESR+REG_BG), and (3) SESR with sorbent regeneration using biogas and adding a pressure swing adsorption (PSA) unit for hydrogen purification (SESR+REG_BG+PSA). When using biogas as fuel (Cases 2 and 3), these configurations were studied using air and oxy-fuel combustion atmospheres in the sorbent regeneration step, resulting in five case studies. A thermodynamic approach for process modeling can provide the optimal process operating conditions and configurations that maximize the energy efficiency of the process, which are the basis for subsequent optimization of the process at the practical level needed to scale up this technology. For this purpose, process simulations were performed using a steady-state plant model developed in Aspen Plus, incorporating a complex heat exchanger network (HEN) to optimize heat integration. A comprehensive parametric study assessed the

We are currently facing a new energy scenario, in which it is necessary to implement new negative emission technologies to eliminate CO₂ from the atmosphere. These technologies include the BECCUS processes (bioenergy with carbon capture, utilization, and storage). Due to their relevance in the context of bioenergy, both biogas and biomethane are postulated as important renewable energy sources. The use of biomethane contained in biogas, as a substitute for methane of fossil origin (natural gas), necessarily requires a purification, or upgrading, which is a process that separates the CO₂. In order to evaluate the environmental benefit of this technology, a Life Cycle Assessment (LCA) of the biogas purification process is proposed. This process integrates a PSA (pressure swing adsorption) unit, which is a fundamental part of the CO₂/CH₄ separation process. Whether considering the recovered CO₂ as a waste or as a product, the results obtained showed that, regardless of the energy source used (renewable or fossil), biogas purification with CO₂ capture results in a negative environmental impact value, since, firstly, carbon dioxide emissions are reduced (which is not emitted into the atmosphere), and also the captured CO₂ could have a second useful life. It is, therefore, a clear example of a circular economy.

Large-language models (LLMs) such as GPT-4 caught the interest of many scientists. Recent studies suggested that these models could be useful in chemistry and materials science. To explore these possibilities, we organized a hackathon. This article chronicles the projects built as part of this hackathon. Participants employed LLMs for various applications, including predicting properties of molecules and materials, designing novel interfaces for tools, extracting knowledge from unstructured data, and developing new educational applications. The diverse topics and the fact that working prototypes could be generated in less than two days highlight that LLMs will profoundly impact the future of our fields. The rich collection of ideas and projects also indicates that the applications of LLMs are not limited to materials science and chemistry but offer potential benefits to a wide range of scientific disciplines.

Pharmaceuticals are able to evade conventional wastewater treatments and therefore, are recurrently found in the environment with proven potential to cause harm to human and wildlife. Adsorption onto activated carbon (AC) is a promising complement. However, AC production from non-renewable resources and its difficult after-use recuperation are prohibitive. Hence, a waste-based magnetic activated carbon (MAC) was produced from paper mill sludge, via an ex-situ synthesis, for the adsorptive removal of carbamazepine (CBZ), sulfamethoxazole (SMX) and ibuprofen (IBU) from ultrapure water and wastewater. The MAC was obtained through the promotion of electrostatic interactions between magnetic and activated carbon particles in a water suspension at controlled pH between the points of zero charge of both surfaces. The optimized condition (MACX3) presented remarkable properties regarding specific surface area (SBET=795 m2 g-1) and saturation magnetization (MS=19 emu g-1). Kinetic and equilibrium adsorption studies were performed under batch conditions. Adsorption equilibrium was reached in up to 30 min for all pharmaceuticals in both matrices, proving the low dependence on the adsorbate and the broad applicability of MACX3 in pharmaceutical adsorption. Regarding equilibrium experiments, high Langmuir maximum adsorption capacities (qm) were achieved in ultrapure water (up to 711 ± 40 µmol g-1). Equilibrium studies in wastewater revealed a decay in qm when compared to ultrapure water: 28% for CBZ (468 ± 20 µmol g-1 (111 ± 5 mg g-1)), 78% for SMX (145 ± 10 µmol g-1 (37 ± 3 mg g-1)) and 62% for IBU (273 ± 8 µmol g-1 (56 ± 2 mg g-1)), attributed to the wastewater pH, which dictates the speciation of the pharmaceuticals and controls electrostatic interactions between pharmaceuticals and MAC, and to competition effects by organic matter. It was demonstrated the promising applicability of a waste-based ex-situ MAC, rapidly retrievable from water, as an alternative tertiary wastewate

The fermentation of syngas is an attractive technology that can be integrated with gasification of lignocellulosic biomass. The coupling of these two technologies allows for treating a great variety of raw materials. Lignin usually hinders microbial fermentations; thus, the thermal decomposition of the whole material into small molecules allows for the production of fuels and other types of molecules using syngas as substrate, a process performed at mild conditions. Syngas contains mainly hydrogen, carbon monoxide, and carbon dioxide in varying proportions. These gases have a low volumetric energy density, resulting in a more interesting conversion into higher energy density molecules. Syngas can be transformed by microorganisms, thus avoiding the use of expensive catalysts, which may be subject to poisoning. However, the fermentation is not free of suffering from inhibitory problems. The presence of trace components in syngas may cause a decrease in fermentation yields or cause a complete cessation of bacteria growth. The presence of tar and hydrogen cyanide are just examples of this fermentation’s challenges. Syngas cleaning impairs significant restrictions in technology deployment. The technology may seem promising, but it is still far from large-scale application due to several aspects that still need to find a practical solution.

To achieve net zero carbon emissions from energy systems, biogas has become an attractive renewable resource for hydrogen production. The sorption enhanced steam reforming (SESR) process is proposed to produce high-purity hydrogen from biogas, enabled by combining the catalytic reforming reaction with the simultaneous CO2 removal by sorption in a single reactor. One of the most critical challenges in using biogas in conventional reforming processes is the presence of H2S since it may deactivate the reforming catalyst. Here we experimentally study the effect of the biogas H2S concentration on the H2 production by SESR, i.e., accounting for the presence of a CaO-based solid sorbent. This work was performed in a fixed-bed reactor using a Pd/Ni-Co hydrotalcite-like material (HT) catalyst and dolomite as CO2 sorbent. Biogas (60CH4/40CO2 vol.%) with different concentrations of H2S (150, 350, 500 and 1000 ppm) was evaluated. The catalyst did not deactivate for biogas H2S concentrations of 150 and 350 ppm during five cycles of the SESR process. However, a slight decrease in the catalyst activity was detected under higher sulfur concentrations after the third SESR cycle. Sulfur was detected in the spent catalyst and sorbent materials, with a higher proportion in the sorbent for the highest H2S concentration tested (1000 ppm). H2 yield decreased by 10.8% and 4.5% points for biogas H2S concentrations of 500 and 1000 ppm after five cycles, respectively, while H2 purity decreased by only 3 vol.% and 2 vol.% points, respectively.

H2 production by sorption enhanced steam reforming (SESR) of bio-oil/biogas blends was demonstrated in a fluidized bed reactor. It combines steam reforming (SR) with simultaneous CO2 capture by a solid sorbent. SESR was performed on a Pd/Ni-Co catalyst derived from a hydrotalcite-like material (HT) using dolomite as CO2 sorbent. Bio-oil from fast pyrolysis of biomass is a carbon–neutral and renewable energy source with great potential for clean H2 production by steam reforming processes. Biogas is also a promising renewable bio-based resource for hydrogen generation that can be used to increase the H2 production of a biomass-based plant. In turn, it could improve the energy efficiency of the process due to the exothermic reaction of the CO2 contained in biogas with the sorbent. Bio-oil composed of acetic acid and acetone (1/1 mol/mol) and biogas composed of CH4 and CO2 (60/40 vol%) were used as fuels. They were blended (50 wt% bio-oil + 50 wt% CH4) to study the SESR process. Effects of temperature, steam/C molar ratio, and pressure on the process performance were evaluated. SESR results showed an effective reforming of bio-oil/biogas blends and an enhancement in the H2 production and fuel conversion compared to conventional SR. Higher temperature and steam/C ratio, but lower pressure, favored H2 yield and purity. High H2 yield (87.1%) and H2 purity (98.6 vol%) were obtained at 625 °C and 2.5 bar (steam/C molar ratio three times higher than the stoichiometric value). The thermodynamic energy analysis of the SESR of bio-oil/biogas blends rendered 1.34% higher cold gas efficiency (CGE) than bio-oil SESR.

In this study, a waste-based magnetic activated carbon (MAC) was used for the first time in a continuous-flow stirred tank reactor (CSTR). The aim was to evaluate the dynamic removal of diclofenac (DCF) from water and wastewater. Firstly, the breakthrough curves corresponding to DCF adsorption from distilled water at different feed flow rates and doses of MAC were determined. After selecting the most favourable conditions, namely 0.18 h L-1 flow rate and 400 mg L-1 of MAC, the effect of different aqueous matrices was studied, with the breakthrough curves evidencing a performance decline in wastewater in comparison with distilled water. Finally, the exhausted MAC was magnetically recovered, regenerated by microwave-assisted heating and applied in two subsequent adsorption cycles. The regeneration studies pointed to a decrease of the specific surface area and an improvement of the magnetic retrievability of MAC. After the first regeneration step, just mild effects were observed in the dynamic adsorptive performance of MAC. However, after a second regeneration step, the performance declined ca. 50%. Overall, the results highlight the feasibility of producing waste-based magnetic composites that simultaneously combine high adsorption efficiency under dynamic operation in a CSTR, with easy retrievability and successful one-stage regeneration for further reutilization.

This study aimed at optimizing the one-step chemical activation and microwave pyrolysis of an agro-industrial waste to obtain a microporous activated carbon (AC) with superior textural and adsorptive properties by a fast, low-reagent and low-energy process. Spent brewery grains were used as precursor, and the antibiotics sulfamethoxazole (SMX), trimethoprim (TMP) and ciprofloxacin (CIP) were considered as target adsorbates. A fractional factorial design was applied to evaluate the effect of the main factors affecting the preparation of AC (activating agent, activating agent:precursor ratio, pyrolysis temperature and residence time) on relevant responses. Under optimized conditions (K2CO3 activation, pyrolysis at 800 °C during 20 min and a K2CO3:precursor ratio of 1:2), a microporous AC with specific surface area of 1405 m2 g-1 and large adsorption of target antibiotics (82-94%) was obtained and selected for further studies. Equilibrium times up to 60 min and maximum Langmuir adsorption capacities of 859 µmol g-1 (SMX), 790 µmol g-1 (TMP) and 621 µmol g-1 (CIP) were obtained. The excellent textural and adsorptive properties of the selected material were achieved with a very fast pyrolysis and low load of activating agent, highlighting the importance of optimization studies to decrease the environmental and economic impact of waste-based AC.

This work aimed at producing easily recoverable magnetic iron-oxide functionalized activated carbons (AC) through environmentally and energetically sustainable methods, evaluating their efficacy towards the removal of the pharmaceuticals diclofenac (DCF) and venlafaxine (VEN) from different aqueous matrices (ultrapure water and wastewater treatment plant effluents). Two AC were prepared by chemical activation of a biomassic industrial waste followed by either conventional (CP) or microwave (MW) pyrolysis. Then, magnetic iron oxide nanoparticles were loaded onto the produced AC. Differences related to the production procedure were not especially remarkable, since both the resulting magnetic composites (MAC-CP and MAC-MW) presented well-developed micropore structures with specific surface areas of 644 and 548 m2 g−1 and saturation magnetization of 32.9 and 22.5 emu g−1, respectively, which conferred them a high adsorptive performance and efficient magnetic recovery from solution. The kinetic data were well described by both pseudo-first and pseudo-second order models. As for the equilibrium data, Langmuir isotherm provided a good fitting, with maximum adsorption capacities ranging between 97 ± 2 and 215 ± 4 µmol g−1 for MAC-CP and between 80 ± 2 and 172 ± 3 µmol g−1 for MAC-MW. Additionally, in binary (DCF and VEN) solutions and wastewater, adsorption onto both MAC was somewhat inhibited due to competitive effects. MW-assisted regeneration of exhausted MAC was effective, as their adsorptive properties and chemical surface features (according to X-Ray photoelectron spectroscopy) remained unchanged. Overall, the produced waste-based magnetic carbon composites simultaneously combine high adsorptive efficiency, easy retrievability and successful regeneration/reutilization.

This work aimed at the microwave-assisted production of activated carbon (AC) from primary paper mill sludge (PS) for the adsorption of antibiotics from water. Production conditions, namely pyrolysis temperature, pyrolysis time and activating agent (KOH):PS ratio, were optimized as a function of product yield, specific surface area (SBET), total organic carbon (TOC) content and adsorptive removal percentage of two target antibiotics (amoxicillin (AMX) and sulfamethoxazole (SMX)). Under the optimized conditions (pyrolysis at 800 °C during 20 min and a KOH:PS ratio of 1:5), a microporous AC (MW800-20-1:5, with SBET = 1196 m2 g-1, TOC = 56.2% and removal of AMX and SMX = 85% and 72%, respectively) was produced and selected for further kinetic and equilibrium adsorption studies. The obtained results were properly described by the Elovich reaction-based kinetic model and the Langmuir equilibrium isotherm, with maximum adsorption capacities of 204 ± 5 mg g-1 and 217 ± 8 mg g-1 for AMX and SMX, respectively. Considering the satisfactory comparison of these results with the performance of commercial and alternative AC produced by conventional pyrolysis, this work demonstrated the feasibility of the microwave-assisted production of environmentally and energetically sustainable waste-based AC to be applied in the efficient removal of antibiotics from water.

Woody biomass pellets' demand for primary energy production is increasing. To guarantee sustainable and cost-efficient pellet production the diversification of biomass feedstock is mandatory. In this work it is proposed to re-use the solid biochar obtained from pyrolysis of eucalyptus (PEc) at 700 °C as an additive to produce enhanced pine sawdust (PIN) pellets. The process required the addition of glycerol as a lubricant in a percentage of 1 and 2 wt% per 5 and 10 wt% of pyrolyzed eucalyptus in the blend, respectively. Small additions of PEc enhanced PIN pellets’ grindability and water-resistance, providing products with remarkable values of durability (up to 99%), net calorific value (up to 20 MJ/kg), energy density (up to 13.3 GJ/m3), and particle density (up to 1.24 g/cm3). N, S, chlorine, and heavy metals contents were also analyzed. The proposed pellets fulfill the A1/A2 and the I1/I2 quality classes for domestic and industrial wood pellets, respectively. A preliminary economic evaluation indicated that pellets made up from a mixture of 90% PIN and 10% PEc are competitive compared to raw PIN pellets, with expected savings in the costs of production, energy, transport, and construction of a storage site of 4, 13, 10 and 7%, respectively.

Energy generation from non-hazardous waste streams, which are unfeasible to be reused or recycled, can help overcome some of the problems related to fossil fuel depletion, global increase in energy demand and waste generation management under restricted landfilling. One of the main drawbacks of waste-to-energy strategies is the poor combustion properties of waste, which densification could help to circumvent. This work studies the co-pelletization of refused derived fuel (RDF) and pine sawdust (PIN) in a continuous pilot pellet mill that resembles industrial pelletization. The effect of RDF contents up to 90 wt% on a set of parameters has been assessed: pelletization energy consumption, physical properties (durability, particle and bulk densities), net calorific value and energy density of the obtained pellets. In addition, slagging, fouling and corrosion, phenomena associated with combustion, were estimated from the ash composition. Results showed that obtaining pellets with a low RDF loading (2–9 wt%) was feasible. They accomplished ISO 17225-2 solid biofuels standard for industrial use, and presented low deposition and corrosion risks. On the other hand, pellets with 30–90 wt% RDF were also manufactured and complied with the UNE-EN 15359:2012 solid recovered-fuel standard for energy recovery in incineration and co-incineration plants. All the produced pellets presented durability and net calorific value above 96.9% and 10.7 MJ/kg, respectively. Energy density higher than 10.6 GJ/m3 was obtained for pellet formulations with RDF content up to 50 wt%. It was demonstrated that the blends of RDF and PIN can provide high-quality pellets with a high load of waste material, under the same operational conditions required for PIN pelletization. It is a versatile process that can be tailored to different product requirements depending on the end-use. It promotes energy recovery and generates value out of a waste fraction with no relevant use, adding economic and environment

The main goal of this work was to produce an easily recoverable waste-based magnetic activated carbon (MAC) for an efficient removal of the antiepileptic pharmaceutical carbamazepine (CBZ) from wastewater. For this purpose, the synthesis procedure was optimized and a material (MAC4) providing immediate recuperation from solution, remarkable adsorptive performance and relevant properties (specific surface area of 551 m g and saturation magnetization of 39.84 emu g) was selected for further CBZ kinetic and equilibrium adsorption studies. MAC4 presented fast CBZ adsorption rates and short equilibrium times (< 30–45 min) in both ultrapure water and wastewater. Equilibrium studies showed that MAC4 attained maximum adsorption capacities (q) of 68 ± 4 mg g in ultrapure water and 60 ± 3 mg g in wastewater, suggesting no significant interference of the aqueous matrix in the adsorption process. Overall, this work provides evidence of potential application of a waste-based MAC in the tertiary treatment of wastewaters. [Figure not available: see fulltext.].

H2 production from biogas (60%CH4 + 40%CO2) by sorption enhanced steam reforming (SESR) was thermodynamically and experimentally studied in a fluidized bed reactor. Biogas is an interesting renewable biomass resource for hydrogen production due to its sustainable nature. SESR combines the catalytic reforming reaction of biogas with simultaneous CO2 removal in a single step. A Pd/Ni–Co hydrotalcite-like material (HT) was used as catalyst and dolomite as CO2 sorbent. The effects of temperature (550–800 °C), steam/CH4 molar ratio (2–6) and gas hourly space velocity (GHSV) (492–3937 mL CH4 gcat−1 h−1) on the process performance were evaluated. CO2 in biogas was effectively removed by the sorbent from the gas phase at 550–700 °C, without influencing the reforming process. H2 yield increased with temperature from 550 to 650 °C, but H2 concentration decreased at temperatures higher than 600 °C, requiring a tradeoff between both parameters to select an optimum operating temperature. H2 purity of 98.4 vol% was obtained at 550–600 °C and H2 yield of 92.7% was reached at 650 °C. Higher steam/CH4 ratios enhance the process, whereas higher space velocities decrease H2 yield. Results demonstrate that high-purity high-yield biohydrogen can be produced by the SESR of a renewable biomass resource as biogas.

Biogas is a valuable source of renewable energy produced from biodegradable organic materials via anaerobic digestion. The production of H2 by sorption enhanced steam reforming (SESR) of biogas has been studied thermodynamic and experimentally. A Pd/Ni–Co catalyst and dolomite as CO2 sorbent were used. The effect of biogas composition (CH4/CO2 vol.%) on the process was evaluated at 600 and 650 °C in a fluidized bed reactor using biogas CO2 concentrations of 5–50 vol.%. During conventional biogas steam reforming (SR), high CH4 partial pressures in the feed favor the process, producing high H2 concentrations. During biogas SESR, CO2 was effectively removed from the gas phase by the sorbent for all the biogas compositions, and it did not alter the process compared to pure methane. Steam methane reforming (SMR) and water-gas shift (WGS), together with carbonation, were the main reactions occurring during biogas SESR. Dry (or CO2) methane reforming did not occur under the conditions studied due to the relatively low temperature and the presence of steam. High H2 purity (98.4 vol.%) and H2 yield (91%) were experimentally obtained, pointing out the biogas SESR as a promising technology for the efficient production of high-purity, high-yield hydrogen from a renewable source.

The use of bio-waste for the production of bio-based adsorbents not only has intrinsic benefits to the environment but is also a route for its valorization. Based on the concept of a circular economy, this book chapter aims to provide an overview of present trends and future potential in the conversion of bio-waste into bio-based adsorbents with particular emphasis on its application to carbon dioxide capture. Bio-based adsorbents have recently gained considerable attention as benign and cost-effective materials for CO2 capture applications. These adsorbents can be produced from cheap and widely available biomass feedstocks and bio-wastes from different industries (e.g., dairy manure, forestry, and agricultural). As a result, a carbon-rich material of hydrophobic nature is obtained, which is activated to gain high porosity development, and it requires mild regeneration conditions. However, large-scale deployment of bio-based adsorption processes remains challenging.

El biogás es un recurso biomásico sostenible debido a su naturaleza renovable que puede ser utilizado para la producción de biometano, como sustituto del metano de origen fósil, y de hidrógeno. El hidrógeno se considera uno de los futuros vectores energéticos más limpios si se genera a partir de fuentes renovables.

Pellets for industrial use were produced from blends of pine sawdust (PIN) and alternative residual biomasses in a pilot-scale pelletizer. The effect of the pelletization temperature (T = 50–80 °C) and biomass moisture content (MC = 14–20%) on pine sawdust pellet quality was studied by using response surface methodology (RSM). Pelletization performance was evaluated on the basis of the durability, bulk density, moisture content, lower heating value (LHV), energy density, diameter, length and density of the pellets. From the RSM analysis, a maximum durability value of 99.4% was obtained at T = 80 °C and MC = 16.6%. Under these conditions, all the parameters showed values within the required range of industrial pellet qualities, i.e., a bulk density of 616 kg/m3, a pellet moisture content of 7.6%, a lower heating value (as received) of 18 MJ/kg, a diameter of 6.2 mm and a length of 23.4 mm. Blends of pine sawdust with eleven unconventional biomass samples were then pelletized under the optimum conditions to obtain pellets for industrial use according to the categories of quality defined by ISO 17225-2. Blends of pine sawdust with almond shells (AS) and olive stones (OS) contents of up to 30 wt%, as well as with pine cone leafs (PCL) contents of up to 15 wt%, produced I1 pellets. Blends of pine sawdust with coffee dregs (CD), coffee husks (CH) and grape pomace (GP) proportions of up to 10 wt%, as well as with hazelnut shells (HS), miscanthus (MIS), pine kernel shells (PKS) and switchgrass (SG) contents of up to 15 wt%, and also with a PCL content of between 15 and 30 wt%, generated I3 class pellets. Classification was not possible for cocoa shells (CS) mixed with pine sawdust due to the low bulk density of the pellets. Energy consumption resulting from the pelletization of the blends was evaluated with values ranging from 0.09 to 0.33 kWh/kg, while the pelletization of pine sawdust required 0.18 kWh/kg. The addition of alternative biomass feedstocks to pine sawdust may

Multivariate analysis was used to study the influence of the biomass characteristics on the gasification process. Ten lignocellulosic biomass samples (almond shells –AS–, chestnut sawdust –CHE–, torrefied chestnut sawdust –CHET–, cocoa shells –CS–, grape pomace –GP–, olive stones –OS–, pine cone leafs –PCL–, pine sawdust –PIN–, torrefied pine sawdust –PINT–, and pine kernel shells –PKS–) were gasified in a bubbling fluidized bed gasifier under an air-steam atmosphere. Statistical analysis was applied to the variables that described the results of the gasification process, i.e., gas concentration, gas production (moles), calorific value of the product gas, energy density, and cold gas efficiency, together with the main biomass properties, such as those derived from the elemental and proximate analyses, the higher heating value (HHV), the particle density, and the elemental composition of the ashes. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were applied to the data of biomass properties and gasification parameters in order to elucidate which feedstock features had a more determinant influence on the gasification process. Both HCA and PCA revealed a clear separation of the biomass samples into two main groups on the basis of the gasification results. The results indicated that PKS, PCL, PINT, OS and PIN biomasses were characterized by high production of combustible gases, such as CO and CH4, high conversion and cold gas efficiency during gasification. This indicated that the most important biomass properties for promoting the gas production, calorific value of the product gas, gasification conversion and energy efficiency were the C and H contents and the HHV of the biomass. However, biomasses CS and GP were mainly characterized by high H2 concentration and H2/CO molar ratio in the gas product, which was mainly related to the higher H/O ratio and K2O ash content of the biomass. The H2 concentration in the product gas was negatively rela

Hydrogen is currently mainly obtained by steam reforming (SR) of natural gas, consuming a high amount of energy to produce H2 with low purity and yield. To overcome these issues, Sorption Enhanced Steam Reforming (SESR) is emerging as a novel process that combines SR with in situ CO2 capture to produce high-purity and high-yield H2. In this work, biogas is proposed as a renewable feedstock in SESR, and the process has been simulated in Aspen Plus to perform an energy analysis. Air is used as the regeneration agent and biogas as a fuel in the sorbent regeneration unit (REG) for sorbent recovery, allowing cyclic operation. The flue gas heat recovery system is modeled using CO2 as the energy source for steam production and H2 as the energy source for air preheating. High H2 yield (96.07%) and purity (95.40 vol.%) were obtained from biogas SESR regardless of biogas composition. The Potential Net Efficiency of biogas SESR, including sorbent regeneration, was in the range of 69.98%-76.77% depending on biogas composition.

Using non-hazardous wastes as an energy source presents a series of advantages that help facing fossil fuel depletion, global increase in energy demand, and continuous growth of wastes generation. If wastes are from biomass origin, they also permit reducing greenhouse gas emissions. Some drawbacks already identified when using wastes as an energy source are the poor physical and energy properties, besides their heterogeneity. These issues can be solved by densification. This work focused on the co-pelletization of pine sawdust and biomass-based wastes. Results indicate that an adequate balance of raw pine sawdust with low-cost wastes of different origins provides pellets with physical and energy properties that accomplish international standards that regulate fuels for wide-range uses, from domestic to industrial heating. Besides, the estimated costs indicate that the proposed formulations are cost-competitive when compared to raw pine sawdust pellets.

Clean energy technologies will play a decisive role in power generation and energy mix short-term scenarios to mitigate the environmental problems derived from increasing global energy consumption. In this context, green hydrogen will foreseeably become a clean and environmentally friendly energy carrier for sustainable development. Biogas is a valuable source of renewable energy and a secondary energy carrier produced from biodegradable organic materials via anaerobic digestion. It is mainly composed of CH4 (35-75 vol.%) and CO2 (15-55 vol.%). The present work proposes utilizing biogas for green hydrogen production by the sorption enhanced steam reforming (SESR) process. SESR has recently emerged as a novel promising method to improve hydrogen production efficiency. It combines, in a single unit, hydrogen production and carbon dioxide separation by a solid CO2 acceptor. The objective of the present work is to prove the feasibility of the SESR of biogas to produce high-purity and highyield hydrogen. To this aim, a comprehensive assessment of the process was carried out by evaluating the effect of the operating conditions on biogas SESR to optimize hydrogen production

In view of a simple after-use separation, the potentiality of producing magnetic activated carbon (MAC) by intercalation of ferromagnetic metal oxide nanoparticles in the framework of a powder activated carbon (PAC) produced from primary paper sludge was explored in this work. The synthesis conditions to produce cost effective and efficient MACs for the adsorptive removal of pharmaceuticals (amoxicillin, carbamazepine, and diclofenac) from aqueous media were evaluated. For this purpose, a fractional factorial design (FFD) was applied to assess the effect of the most significant variables (Fe3+ to Fe2+ salts ratio, PAC to iron salts ratio, temperature, and pH), on the following responses concerning the resulting MACs: Specific surface area (SBET), saturation magnetization (Ms), and adsorption percentage of amoxicillin, carbamazepine, and diclofenac. The statistical analysis revealed that the PAC to iron salts mass ratio was the main factor affecting the considered responses. A quadratic linear regression model A = f(SBET, Ms) was adjusted to the FFD data, allowing to differentiate four of the eighteen MACs produced. These MACs were distinguished by being easily recovered from aqueous phase using a permanent magnet (Ms of 22–27 emu g−1), and their high SBET (741–795 m2 g−1) were responsible for individual adsorption percentages ranging between 61% and 84% using small MAC doses (35 mg L−1).

The design of a pressure swing adsorption (PSA) system requires the development of a complex model that can describe the dynamics of adsorption in a fixed-bed, which means a labor intensive and time consuming work, especially when several adsorbents are going to be compared. Therefore, it would be very useful to establish a simple procedure to quickly assess the performance during the early stages of PSA systems design. The aim of this work is to develop a simplistic approach that drives the decision-making process on the adsorbent in a shorter time. A combined experimental and numerical study of CO2/CH4 adsorption is presented. Thus, three commercial activated carbons are compared in their performance to separate CO2 from biogas under PSA conditions by means of equilibrium adsorption data. A straightaway model, developed to approach PSA systems in a very simple way, where the only input is equilibrium of adsorption data, has been adopted. The Adsorption Figure of Merit (AFM), CO2 purity and CO2 recovery were selected as performance indicators and they have pointed out one of the activated carbons, MC27, as the most promising adsorbent candidate to separate CO2/CH4 by means of PSA. A sensitivity analysis of the process performance as a function of the bed dimensions has been addressed using the developed short-cut model.

he present study investigates the air-steam gasification of ten commercial and alternative lignocellulosic biomass fuels (pine sawdust, chestnut sawdust, torrefied pine sawdust, torrefied chestnut sawdust, almond shells, cocoa shells, grape pomace, olive stones, pine kernel shells and pine cone leafs) in order to evaluate the product gas composition and the process performance in a bubbling fluidized bed gasifier with focus on the different biomass properties. Accordingly, an effort to correlate the biomass characteristics with the gasification results has been done. Pine kernel shell (PKS) was used to test the effect of the gasification temperature (700, 800 and 900 °C), steam to air ratio in the gasifying agent (S/A = 10/90, 25/75, 50/50 and 70/30) and stoichiometric ratio (SR = 0.13 and 0.25) on the product gas composition, combustible gas (H2 + CO + CH4) production, H2/CO ratio, heating value, energy yield and cold gas efficiency of the obtained gas. Results showed that higher temperature and S/A ratio favored H2 production and gasification performance. A higher value of SR slightly affected the gas composition, but led to a higher process efficiency as a consequence of a higher biomass conversion into gaseous combustible products. All the biomass samples of different origin and characteristics were then gasified at the best experimental conditions found (900 °C, S/A = 70/30, SR = 0.25). Gasification of all the biomasses was feasible and H2 and combustible gas concentrations of 30–39 vol% and 59–78 vol% (inert gas-free basis), respectively, were obtained for the biomasses studied, with energy yields of 8–18 MJ/kgbiomass. Torrefied biomass showed similar combustible gas production than the corresponding raw biomass under the conditions studied, but it gave slightly higher H2 production and efficiency results. Possible correlations of the gasification performance parameters with biomass properties were also analyzed. The results showed positive effects of biomass

Twelve commercial and unconventional biomass fuels were evaluated in steam gasification; these include samples of hard (wood, almond, olive and pine kernel wastes) and soft (miscanthus, switchgrass, coffee, cocoa and grape wastes) biomass. Gasification tests at 700–1000 °C of biomass chars obtained from a bubbling fluidized bed reactor were performed in a TG analyzer. Steam gasification kinetics were extensively analyzed: an index of key parameters for the twelve biomasses and the correlation to biomass ash composition were developed. The random pore model (RPM) described the experimental reactivity best, with activation energies of 59–196 kJ mol−1. The study of their reactivities provided a ranking of fast-, medium- and slow-kinetics fuels. The influence of alkaline and alkaline-earth metals (AAEM) on reactivity revealed that K, Na and Mg had a positive effect while Si, P and Ca had a negative influence.