Microalgae serve as efficient biological platforms for CO2 capture, and their catalytic pyrolysis offers a sustainable route to convert renewable carbon into a hydrocarbon-rich bio-oil precursor, with catalysts playing a key role in upgrading pyrolysis vapors and improving fuel quality. Layered materials, a promising class of solid acid catalysts, are expected to enhance the deoxygenation of bio-oil, facilitating its conversion into hydrocarbon-rich bio-oil precursors. In this context, the innovative contribution of this work lies in exploring the potential of four catalysts, Ni-Al layered double hydroxide (NALH), aluminum-containing layered magadiite (ALMG), titanium-containing layered magadiite (TIMG), and potassium hexaniobate (KHEX), on the pyrolysis vapors of Chlorella sp. microalgae. Experiments were conducted in an analytical pyrolyzer (Py-GC/MS) at 500 °C using a 5:1 catalyst-to-biomass ratio. The pyrolysis of Chlorella sp. microalgae primarily yielded oxygen-containing compounds (40.1%). Catalytic Py-GC/MS analysis revealed that layered materials are effective for converting microalgae into renewable hydrocarbons and for reducing the content of oxygenated compounds in upgraded condensable volatile products. Among the catalysts, TIMG exhibited the highest selectivity for aromatic hydrocarbons (2.2-fold increase) and the highest hydrocarbon recovery (73.2%). However, when the focus shifted to maximizing the degree of deoxygenation (88.4%) and selectivity for C5-C12 hydrocarbons (87.6%), NALH proved to be the most effective catalyst. The results demonstrate that layered materials are promising catalysts for converting microalgae into hydrocarbon-rich bio-oil, offering a sustainable, renewable alternative to petroleum-derived fuels and supporting bioeconomy development.

A crescente demanda por fontes energéticas sustentáveis tem impulsionado o desenvolvimento de tecnologias voltadas à transição para uma economia de baixo carbono. Nesse contexto, o biogás destaca-se como uma alternativa estratégica por integrar produção de energia, gestão de resíduos e mitigação de emissões de gases de efeito estufa. Este estudo tem como objetivo analisar as tendências científicas e tecnológicas relacionadas ao biogás no contexto da transição energética, por meio de uma abordagem bibliométrica. A pesquisa foi realizada com base em dados extraídos da base Scopus, utilizando como palavras-chave biogas, renewable energy, CH4, CO2 e anaerobic digestion, sem delimitação temporal, resultando em um conjunto de 220 artigos científicos. Os dados foram tratados e analisados com o auxílio do software VOSviewer, permitindo a construção de mapa de coocorrência e a identificação de padrões na produção científica. Os resultados indicam crescimento significativo das publicações a partir de 2004, com destaque para Estados Unidos e China como principais polos de pesquisa, além da presença do Brasil. A análise evidenciou a formação de clusters temáticos relacionados à digestão anaeróbia, sustentabilidade ambiental, gestão de resíduos e energias renováveis, demonstrando o caráter interdisciplinar do biogás. Conclui-se que o biogás apresenta elevado potencial para contribuir com a transição energética, especialmente em países com ampla disponibilidade de biomassa residual. No Brasil, a expansão do biogás exige investimentos em infraestrutura, inovação e políticas públicas, sendo a análise bibliométrica essencial para orientar planejamento e desenvolvimento científico-tecnológico.

The production of alternative fuels to replace fossil-derived products constitutes a significant research topic, given the need for sustainable solutions that support energy transition and decarbonization of the transport sector. In this context, this pioneering study investigates the co-pyrolysis of Agave sisalana (sisal) bagasse with two types of multilayer plastic waste: polyethylene film with an aluminum barrier (PFA) and polyethylene film with an ethylene-vinyl alcohol barrier (PFE). The experiments were conducted in a micro-pyrolyzer coupled with gas chromatography and mass spectrometry (Py-GC/MS), using a simplex centroid mixture design to optimize compositions and principal component analysis (PCA) to interpret the data. While the isolated pyrolysis of sisal bagasse resulted in 58.78 % oxygenated compounds, co-pyrolysis with 50 % PFA provided a maximum yield of 91.39 % aliphatic hydrocarbons, representing a 2.97-fold increase compared to the pyrolysis of the isolated residue. PFA demonstrated a superior synergistic effect to PFE when combined with sisal bagasse. The results indicate that this combination can produce hydrocarbon-rich pyrolytic oil, significantly contributing to sustainable waste management and advancing the "waste-to-energy" concept by converting residual materials into alternative transportation fuels.

The increasing frequency of extreme weather events has reduced hydropower reliability, increasing dependence on thermoelectric generation and associated CO2 emissions. Chemical Looping (CL) is a promising low-carbon alternative, enabling efficient energy production with inherent CO2 capture, but its performance depends on robust oxygen carriers (OCs). Despite Brazil holding one of the world's largest manganese reserves, their potential as OCs for CL applications remains largely unexplored. The current study is pioneering in proposing the identification of geographical location of Brazilian mines containing manganese ores with favorable physicochemical properties for application as OC for energy conversion processes with inherent CO2 capture aligning mineral availability with regions of high relevance for geological CO2 storage and proximity to emission hubs. This study evaluates the performance of five manganese-based OC from Para (MnHV, MnHB), Ceara (MnHL, MnLL), and Bahia (MnLB). Their reactivity was evaluated in a thermobalance performing redox cycles under methane and hydrogen atmospheres to assess their oxygen transport capacity, redox kinetics, and phase stability. MnHB showed the highest methane reactivity (RI = 1.89%/min) and high oxygen transport capacity (ROC = 3.99%), MnHL achieved the highest ROC (4.38%) and hydrogen reactivity (RI = 10.10%/min), and MnHV exhibited balanced overall performance, with all samples meeting industrial crushing strength requirements. These results identify Para and Ceara as promising regions for Mn-based oxygen carriers, which are of/close to high relevance areas for geological CO2 storage, supporting the deployment of CL-based BECCS and low-carbon energy systems in Brazil aligned with SDGs 7, 9, and 12.

A crescente demanda por fontes energéticas de baixo carbono tem impulsionado a valorização de resíduos lignocelulósicos como alternativas sustentáveis aos combustíveis fósseis. Nesse contexto, este estudo avaliou o potencial energético das cascas de Mimosa caesalpiniifolia (sabiá), uma espécie nativa da Caatinga, visando sua aplicação como biocombustível sólido. A biomassa foi caracterizada por meio de análises imediata, elementar e composicional, além da determinação de parâmetros energéticos e estimativas de emissões atmosféricas. Os resultados evidenciaram baixo teor de umidade (9,51%) e de cinzas (4,5%), elevado teor de materiais voláteis (74,6%) e teor adequado de carbono fixo, indicando comportamento favorável em processos de conversão termoquímica. O poder calorífico superior (17,7 MJ/kg) e a elevada densidade bioenergética (7,08 GJ/m3) confirmam a competitividade energética do material em relação a outras biomassas lignocelulósicas. Do ponto de vista ambiental, a biomassa apresentou reduções expressivas nas emissões de CO e SO2 em comparação ao carvão fóssil, além de potencial de neutralidade de carbono ao longo do ciclo de vida. Os indicadores de equivalência energética e de retenção de CO2 reforçam sua viabilidade como substituto parcial de combustíveis fósseis. Assim, os resultados demonstram que o aproveitamento energético das cascas de sabiá representa uma alternativa promissora para a diversificação da matriz energética e o fortalecimento da bioeconomia no semiárido brasileiro.

A transição energética global e a busca pela desfossilização do setor de transportes têm impulsionado o desenvolvimento de biocombustíveis avançados a partir de fontes renováveis. O presente estudo avalia o potencial do óleo da semente de Pachira aquatica Aubl., popularmente conhecida como Munguba, como matéria-prima para a produção de hidrocarbonetos renováveis e bioaditivos. A biomassa em questão destaca-se por seu rápido crescimento e por não competir diretamente com a segurança alimentar, sendo composta predominantemente por ácidos graxos, com destaque para o ácido palmítico (44,93% a 60,92%). A metodologia empregada baseia-se na pirólise catalítica (Py-GC/MS) utilizando a zeólita HZSM-5 como catalisador. Diferente da pirólise convencional, que gera um bio-óleo de elevada acidez e viscosidade, o processo catalítico promove reações de desoxigenação (descarboxilação, descarbonilação e desidratação) e o craqueamento de vapores. O uso da zeólita HZSM-5 demonstra eficácia na seletividade para a produção de hidrocarbonetos aromáticos e moléculas de menor peso molecular, resultando em produtos com propriedades semelhantes aos combustíveis fósseis convencionais ("drop-in"). Os resultados indicam que a pirólise flash catalítica do óleo de Munguba representa uma rota tecnológica sustentável e eficiente para a conversão de passivos ambientais em produtos de alto valor agregado, contribuindo para a redução da emissão de gases de efeito estufa e para a diversificação da matriz energética brasileira.

Bismuth-based inorganic perovskites, such as Cs3Bi2I9, offer a non-toxic alternative for solar applications but suffer from poor environmental stability. This study reports the development of a poly(methyl methacrylate-butyl acrylate-methacrylic acid) [P(MMA-BA-MAA)] protective overlayer. Optimized via free-radical solution polymerization with semicontinuous initiator addition, the formulation achieved a 99% conversion rate. FTIR analysis confirmed successful copolymerization through the identification of characteristic vibrational bands, while DSC and UV-Vis revealed a glass transition temperature (T-g) of 43 degrees C and an insulator bandgap of 4.35 eV, respectively. Gravimetric tests showed zero water absorption after 24-h immersion. Notably, both synthesis and encapsulation were performed under high-humidity ambient conditions (similar to 70% RH) without controlled atmospheres. Stability monitoring demonstrated that encapsulated Cs3Bi2I9 films retained their UV-Vis spectral features (shoulders at 422 and 480 nm) for 75 days under sunlight and humidity exposure. SEM characterization corroborated these results by revealing the preservation of the perovskite's hexagonal crystalline morphology after 60 days of stress, whereas non-encapsulated samples degraded completely. Furthermore, the protective layer ensured structural integrity during 3-min direct water submersion. These findings provide a robust, low-cost strategy for the stabilization of lead-free perovskite solar cells.

A crescente contaminação dos recursos hídricos por atividades antropogênicas, especialmente pela presença de metais pesados em efluentes industriais, tem impulsionado o desenvolvimento de tecnologias sustentáveis. Neste estudo, avaliou-se o potencial da casca da castanha de caju (Anacardium occidentale L.), resíduo abundante no Nordeste brasileiro, como bioadsorvente para remoção de íons Cu²? em soluções aquosas. O material foi submetido a tratamentos químicos (NaOH, ácido cítrico e peróxido de hidrogênio) e térmico, visando melhorar suas propriedades adsortivas. Os resultados mostraram que o tratamento com NaOH foi o mais eficiente, com remoção próxima de 100%, enquanto o material calcinado apresentou eficiência intermediária (~75%). Os demais tratamentos não apresentaram ganhos significativos em relação ao material in natura. A otimização foi realizada por planejamento fatorial 3², avaliando a influência da concentração de NaOH e do tempo de contato. Ambos os fatores foram significativos (p<0,05), sendo a concentração o mais relevante. O modelo apresentou excelente ajuste (R² ˜ 0,9943) e foi validado pela ANOVA. A superfície de resposta indicou melhores resultados para concentrações acima de 0,06 mol/L e tempos superiores a 5 h. Além disso, menores concentrações de NaOH mantiveram alta eficiência, reduzindo custos e consumo de água. O estudo evidencia o potencial desse resíduo como alternativa sustentável para remoção de metais pesados.

The present study introduces an innovative and cost-effective approach for producing hydrocarbon-rich biofuels from fast-growing microalgae (Chlorella sp.) by upgrading pyrolysis vapors using low-cost catalysts derived from naturally occurring minerals and industrial wastes. Seven candidate materials were evaluated: three industrial wastes, cement kiln dust (CKD), granite and marble polishing waste (GPW), and kaolin processing waste (KPW); two clay minerals, attapulgite (APG) and palygorskite (PGK); and two naturally occurring zeolites, heulandite (HLD) and clinoptilolite (CPL). Catalysts were characterized and tested in a pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) setup to assess their activity and selectivity. Catalytic upgrading significantly improved bio-oil quality compared to non-catalytic pyrolysis, increasing hydrocarbon content by at least 1.5-fold and reducing oxygenated compounds by over 2-fold. CKD and GPW were the most active catalysts, promoting decarbonylation, decarboxylation, and aromatization reactions to generate deoxygenated bio-oil precursors. CKD showed superior selectivity toward aromatic hydrocarbons, achieving a 2.5-fold increase, while GPW favored aliphatic hydrocarbons, with a 1.9-fold enhancement. Overall, the catalysts demonstrated high selectivity for monoaromatics over polyaromatics and produced hydrocarbons predominantly in the gasoline range (C5-C12). Considering both catalytic performance and economic feasibility, GPW, APG, and CPL emerged as the most promising materials for large-scale applications. The findings highlight a viable pathway to produce drop-in biofuels from microalgae-derived pyrolysis vapors, providing deoxygenated, hydrocarbon-rich intermediates suitable for the transportation sector. This approach addresses key challenges in biofuel production by combining low-cost, abundant materials with efficient upgrading strategies, thereby contributing to the transition toward low-carbon energy systems.

The use of renewable fuels, as biomass, in the chemical looping combustion process becomes an attractive solution to bioenergy technology with CO2 capture (BECCS). In this work, a manganese ore from Brazil (MnT1000) was evaluated as an oxygen carrier to promote the conversion of a pine residue biomass by the in-situ Gasification-Chemical Looping Combustion (iG-CLC) technology in a 0.5 kWth continuous experimental unit installed at ICB-CSIC. The main parameters studied were the influence of fuel reactor temperature, air excess, and oxygen-to-biomass ratio on the performance of the MnT1000 evaluating CO2 capture efficiency and total oxygen demand. Under all experimental conditions, CO2 composition was higher than 84% at the fuel reactor outlet gas on a dry N2-free basis. The unburned gases such as CH4, CO and H2 were present in low concentration, attributed to the high reactivity that MnT1000 has with H2, CO and CH4. In general, higher temperatures, higher oxygen excess ratio and lower oxygen-to-biomass ratio reduced the total oxygen demand, with no great influence on CO2 capture efficiency. Most of the experiments showed capture efficiency above 90%, and a total oxygen demand in between 5.9 and 13.7% for the experimental conditions studied with low specific solid inventories (760 - 833 kg MW- 1). The amount of tar quantified in this study was low, corresponding to a total of 1.32 g Nm- 3, composed mainly of naphthalene and phenanthrene. In all experimental conditions, MnT1000 showed promising behavior, its reactivity remained high and constant throughout whole operation and no agglomeration problems were observed.

Non-edible vegetable oils remain underexplored for energy applications, and their use as precursors for drop-in biofuels aligns with the goals of producing clean and sustainable energy from renewable resources without competing with human food supplies. In this context, the innovative aspect and objective of this study lie in investigating, for the first time, the effects of catalyst bed temperature (300-500 degrees C) and oil/HZSM-5 ratio (3:1, 1:1, and 1:2) on the thermochemical conversion of Pachira aquatica Aubl. (PA) oil via catalytic flash pyrolysis. A full factorial design (32) with gas chromatography, Principal Component Analysis (PCA) and Response Surface Analysis (RSA) was used to understand the influence of operational parameters on hydrocarbon formation. The first two principal components explained 88.42 % of the data variance, revealing a strong relationship between the experimental variables and product selectivity. Moderate catalytic temperatures (300-400 degrees C) and low biomass/catalyst ratios favored producing alkane, alkene and compounds in the range of gasoline, diesel and kerosene. Catalytic pyrolysis of PA oil over HZSM-5 resulted in up to 91.16 % of diesel-grade hydrocarbons and 18.63 % of BTEX aromatic compounds, demonstrating its potential as a renewable energy source. The presence of HZSM-5 was decisive for deoxygenating and selectively forming non-oxygenated and aromatic hydrocarbons of industrial interest, such as xylene. The results demonstrate the technical feasibility of catalytic flash pyrolysis of PA oil, contributing with new data and strategies for efficiently converting this biomass into advanced biofuels, in line with the Sustainable Development Goals related to renewable and affordable energy.

Biofuel production has made significant progress recently, driven by the increasing demand for energy and the availability of abundant and renewable feedstocks in Brazil. Pachira aquatica Aubl. (PA) seeds are presented as a sustainable alternative for of producing thermally stable oil, which was evaluated in this study to generate renewable hydrocarbon precursors for biofuels via flash pyrolysis. PA oil was extracted by mechanical pressing and characterized to determine its fatty acid profile, followed by catalytic and non-catalytic flash pyrolysis using the HZSM-5 catalyst to produce value-added compounds. Fatty acid analysis revealed a predominance of saturated acids, such as palmitic acid (68.55 %), along with unsaturated acids such as oleic (6.58 %) and linoleic (6.13 %). The oil exhibited thermal stability up to 250 degrees C. Non-catalytic pyrolysis produced aliphatic hydrocarbons (C7-C16), mainly in the diesel, gasoline, and kerosene range. At 300 degrees C in a catalytic bed, hydrocarbons in the range of C5-C15 with a drop-in jet fuel profile and aromatic compounds were predominant. At 500 degrees C, hydrocarbons in the range of C4-C13 with increased aromatic bioproducts (BTEX) were observed. These results demonstrate the significant potential of PA seed oil to produce advanced drop-in biofuels and aromatic bioproducts for the chemical industry. Based on the results obtained, future perspectives include obtaining the products, evaluating the economic feasibility of large-scale PA cultivation to increase oil productivity, as well as expanding its applications to new bioproducts.

The increasing accumulation of industrial solid waste poses serious environmental and economic challenges, demanding sustainable strategies for its reuse. In this study, retorted oil shale (RS), in its pure form and impregnated with Fe or Cr, was valorized as a precursor for sustainable ceramic surface coatings. The pigments were synthesized via a wet impregnation method and thoroughly characterized by TG, XRF, XRD, SEM-EDS, FTIR, UV-Vis spectroscopy, and colorimetric analysis. The materials exhibited excellent thermal stability, high luminosity, and tunable chromatic properties (ranging from light brown to red and gray), modulated by the metal species and calcination temperature. When incorporated into ceramic glazes and fired at 1100 degrees C, the pigments maintained their structural integrity and optical performance, demonstrating strong interfacial compatibility with the coating matrix. This technically simple and cost-effective approach supports circular economy principles by converting oil shale waste into high-value, functional coating materials. Overall, this study provides fundamental insights into the microstructural and optical behavior of RS-derived coatings, contributing to the advancement of sustainable ceramic surface technologies.

Finding a suitable oxygen carrier that is both cost-effective and highly reactive across multiple cycles in chemical looping processes remains a challenge. Consequently, this research focuses on the assessment of Fe-, Mn-, and Nibased ores and mine residues as low-cost and sustainable oxygen carriers. Chemical composition, crushing strength, and attrition rate were determined. Their reactivity was evaluated in a thermobalance with CH4, H2, and CO, followed by assessment in a batch fluidized bed reactor with the same gases. All materials exhibited good mechanical properties at the outset, except MinMnT, which lacked the required mechanical strength and was subjected to thermal treatment. MinFeC, MinFeF, and MinMnT1000 demonstrated effective oxygen transport capacity and high reactivity both in thermobalance and FBR, with no agglomeration and a lifetime ranging between 3000 and 10,500 h. Given the outstanding performance of MinMnT1000 with CO and H2, it is considered an excellent candidate for further evaluation in iG-CLC with biomass.

Following a circular economy strategy, recovering value-added hydrocarbons from plastic residues through catalytic pyrolysis is an innovative and promising approach for both resource conservation and refuse valorization. The main objective of the current work is to investigate the impact of tungsten trioxide (WO3) supported on rice husk ash (RHA) as a new, low-cost catalyst on the flash pyrolysis of aluminum foil-laminated plastic residue. The catalyst performance was investigated using a micro-furnace temperature-programmable pyrolyzer interfaced with gas chromatographic separation and mass spectrometry detection. The energy-related attributes of aluminum foil-laminated plastic residue have confirmed its potential as raw material for pyrolytic oil production, owing to its high energy content (31.76 MJ kg(-1) ), volatile matter content (82.5 wt%), moderate ash content (17.5 wt%), negligible fixed carbon content (below 0.01 wt%), and predominant mass loss below 500 degrees C. The catalytic test results demonstrated that the concentration of alkanes increased by 2.5-fold and cyclic aliphatic compounds by 1.9-fold when utilizing the WO3/RHA catalyst compared to non-catalytic pyrolysis. From the hydrocarbon distributions, success was achieved by the WO3/RHA catalyst in the cracking of heavy hydrocarbons (above C12) into valuable light hydrocarbons (C5-C12). The results permit us to conclude that utilizing the WO3/RHA catalyst enhances the yield of alkanes and cyclic aliphatic compounds within the C5-C12 range in the condensable volatile products, which are valuable gasoline-range hydrocarbons. Utilizing the proposed catalyst offers a potentially low-cost way to convert plastic waste into gasoline-range transportation fuel, enabling the achievement of a circular economy for plastic residues through catalytic pyrolysis, unlike traditional treatment methods.

With the climate crisis, the demand for new sustainable fuels to diversify the global energy matrix has intensified. In this context, the co-pyrolysis of biomass/plastic mixtures has emerged as a promising alternative. Therefore, this article proposes a bibliometric analysis, whose novelty lies in identifying thematic patterns, major advances, and challenges faced in the field during the period from 2020 to 2025. Data were extracted from the Scopus and Web of Science platforms, classified according to the PRISMA 2020 methodology as strongly related, weakly related, and unrelated, and analyzed using the VOSviewer and Bibliometrix software tools. From the initial 889 documents (Scopus: 281; WoS: 608), 337 were selected, indicating the scientific leadership of China and India, with a predominance of laboratory-scale studies (TRL 2–3). The recurring use of thermogravimetric analyzers and analytical systems, along with a growing interest in microwave-assisted pyrolysis, was identified. In the catalytic field, HZSM-5 zeolite stands out. Regarding feedstocks, biomass, such as wood and sawdust, prevails, typically combined with widely available polymers, including polyethylene, polystyrene, and polypropylene. The analysis revealed five priority research fronts: (i) scaling up to pilot plants; (ii) low-cost catalysts; (iii) microwave-specific reactors; (iv) diversification of feedstocks, including hard-to-recycle plastics; and (v) strengthening international collaboration networks. These advancements are crucial to establishing co-pyrolysis as a strategic technology within the circular economy and energy transition, directly contributing to the achievement of the Sustainable Development Goals (SDGs 7, 11, 12, and 13).

Developing biofuels with characteristics similar to current fossil fuels and compatibility with existing petroleum infrastructure (drop-in biofuels) is gaining prominence, aligning with global efforts towards carbon-neutral economies and decarbonization of the transportation sector. The originality of the current study involves two directions: first, the use of Chlorella sp. microalgae, cultivated under simulated post-combustion gas, as a raw material for producing drop-in biofuel precursors; and second, an investigation of the catalytic activity of hierarchical zeolites in the deoxygenation and denitrogenation of volatile pyrolysis products, enhancing hydrocarbon content. To accomplish this, a micro-furnace-type temperature-programmable pyrolyzer coupled with chromatographic separation and mass spectrometry detection (Py-GC/MS) was utilized to assess the upgrading effectiveness of distinct zeolites (faujasite-type, MFI-type, and mordenite-type) on volatile pyrolysis products. All tested zeolites effectively reduced oxygenated and nitrogenated compounds in the volatile pyrolysis products, enhancing their suitability for producing renewable fuel. This supports sustainable development goals by promoting affordable, clean energy and climate action. HMor yielded the highest hydrocarbon content (98.5%), followed by HZSM-5 (97.6%) and HY (85.5%). Catalytic upgrading significantly increased the concentration of aromatic hydrocarbons (at least 66.3%), with MFI-type zeolites showing the highest selectivity for valuable BETX compounds (benzene, ethylbenzene, toluene, xylene). Hydrocarbons in the gasoline range, with up to 91.7%, predominantly align with the needs of the transportation fuel market. The principal component analysis illustrates that using MFI-type zeolites promoted the lowest selectivity for PAHs, constituting precursors for coke formation, which is advantageous for ensuring a longer catalyst lifespan. Our results are promising and encourage the conversion of microalgal biomass into renewable fuel additives for formulating drop-in biofuels, as hydrocarbon-rich volatile pyrolysis products could be directly integrated into existing biorefineries. Thus, microalgal biomass cultivated using flue gas as the carbon source can be viewed as a versatile and promising resource for producing renewable fuel additives, contributing to developing a sustainable, low-carbon future.