Journal: Bioresource TechnologyAuthors: Kwangsuk Yoon, Taewoo Lee, Hoyeon Cha, Joohyung Lee, Jegeon Lee, Hocheol SongAbstract:Despite the growing interest in biomass as a carbon–neutral resource, technical challenges have limited its comprehensive utilization. Pyrolysis has emerged as a promising method for reducing the carbon footprint by more effectively valorizing carbon in biomass. This study investigated the use of carbon dioxide (CO2) in the pyrolysis of pine cone (PC), a lignocellulosic biomass. Thermogravimetric analysis confirmed that lignin was the primary component of the PC. Characterization and quantification of the three pyrolytic products (syngas, biocrude, and biochar) revealed that CO2 enhanced CO production and the surface area of the biochar, thereby improving its CO2 adsorption capacity. Additional heat and a Ni catalyst further amplified CO2′s functionality. The sustainability of the proposed pyrolysis system was evaluated by calculating energy requirements of the pyrolysis processes and the net CO2 emissions. Catalytic pyrolysis under CO2 was the most effective, achieving a reduction of 3.34 g of CO2 per gram of PC.Keywords: Waste valorization; Lignocellulose; Pyrolysis; CO2 utilization; Syngas productionDOI: https://doi.org/10.1016/j.biortech.2024.131765

Journal: Industrial Crops and ProductsAuthors: Dohee Kwon, Dongho Choi, Jee Young Kim, Hocheol Song, Jaewon Lee, Eilhann E KwonAbstract:The non-catalytic conversion of non-edible biomass into biodiesel (BD) is the subject of this investigation. Conventional oil extraction from biomass often results in economic and technical inefficiencies. This study suggests a non-catalytic transesterification reaction to directly convert castor seeds into BD in order to overcome these problems. Base-catalysed transesterification of extracted castor seed oil had a BD yield of 84.43 wt% (reaction time: 24 h at 60 ˚C). In contrast, non-catalytic transesterification of castor seed oil produced a BD yield of 93.79 wt%, which completed the reaction in 1 min at 390 ˚C. Thus, using the non-catalytic transesterification approach, we were able to empirically verify the greater conversion efficiency of BD. Additionally, the direct non-catalytic conversion of castor seed to BD achieved a yield of 105.81 wt%, suggesting that substantial oil loss occurs during the extraction process. These findings suggest that the traditional method of converting BD, which involves oil extraction and base-catalysed transesterification, is less efficient and less financially advantageous than directly converting castor seeds into BD.Keywords: Biodiesel; Fatty acid methyl esters (FAMEs); Non-catalytic transesterification; lipid; Castor seedDOI: https://doi.org/10.1016/j.indcrop.2024.119811

Journal: Journal of Analytical and Applied PyrolysisAuthors: Eunji Kim, Kwangsuk Yoon, Gihoon Kwon, Naeun Kim, Gyeongnam Park, Young Jae Jeon, Eilhann E Kwon, Hocheol SongAbstract:The extensive use of fossil fuels and chemicals has resulted in substantial emissions of anthropogenic carbon dioxide (CO2), which in turn have triggered global warming. As a proactive response, converting waste into energy and chemicals is a paramount importance. To maximize carbon utilization, implementing a thermo-chemical process for waste valorization is a promising approach owing to its high tolerance for the intrinsic heterogeneity of waste materials. Thus, the development of thermo-chemical processes that exhibit high productivity and selectivity for valorized products should be prioritized. In this study, we focused on the pyrolysis of paper packaging waste (PPW) as a case study to address these challenges. To enhance the production of syngas and furfural, PPW was pretreated with ferrous sulfate (FeSO4) before undergoing pyrolysis. Slow and fast pyrolysis were conducted to characterize the production of syngas and bio-oil, respectively. The pretreatment of PPW with FeSO4 increases syngas production, attributed to the catalytic properties of iron (Fe). Bio-oil derived from FeSO4-treated PPW contained more homogenized chemicals compared with that from untreated PPW. Furfural selectivity reached 51.1 % when PPW pretreated with FeSO4 (10 wt% of Fe relative to PPW) was pyrolyzed at 600 ˚C. Additionally, biochar produced from FeSO4-treated PPW exhibited a porous carbon structure with a high surface area (123.8 m​2 g-1) and was rich in minerals, such as Fe and calcium (Ca). This biochar catalytically enhanced the reaction kinetics of thermally induced transesterification of soybean oil, resulting in a biodiesel yield of 88.7 % at 350 ˚C. The findings of this study offer a practical approach to establishing a sustainable and carbon-neutral platform for the conversion of lignocellulosic biomass into value-added products.Keywords: Waste valorization; Chemical recycling; Pyrolysis; Biodiesel; Paper packaging wastesDOI: https://doi.org/10.1016/j.jaap.2024.106844

Journal: Chemical Engineering JournalAuthors: Naeun Kim, Gihoon Kwon, Kwangsuk Yoon, Eunji Kim, Gyeongnam Park, Young Jae Jeon, Hocheol SongAbstract:Surplus carbon, in the form of carbon dioxide (CO2), has aggravated global warming over several past decades. To divert the current energy mix that relies heavily on fossil fuels, researchers have realised waste materials as alternative energy. Such attempts could reduce CO2 emissions and potentially contribute to establishing a circular economy. This study investigated the transformation of cattle manure (CM) into value-added products (syngas and furfural) via a thermochemical pathway. The CM was treated with FeCl3 prior to pyrolysis to enhance the conversion selectivity toward syngas and furfural. Slow-pyrolysis was conducted to determine the mechanisms of syngas production, and fast-pyrolysis was undertaken to optimize bio-oil production. Thermogravimetric analysis revealed that Fe impregnation facilitated the thermal degradation of CM, resulting in enhanced syngas formation. The oil product obtained from the Fe-impregnated CM exhibited notable enrichment in furfural and a much simpler chemical composition than that of the untreated CM. Furthermore, the produced biochar catalytically expedited the kinetics of the transesterification reaction of canola oil. The overall results of this study offer a practical means of converting livestock manure into useful resources, thereby contributing to the realisation of a circular economy.Keywords: Circular economy, Manure upcycling, Thermochemical conversion, Furfural, BiodieselDOI: https://doi.org/10.1016/j.cej.2024.155839

Journal: ChemosphereAuthors: Kwangsuk Yoon, Gihoon Kwon, Eunji Kim, Heuiyun Lee, Dong-Jun Lee, Hocheol SongAbstract:This study investigated the thermochemical conversion of cattle manure (CM) to propose a sustainable platform for its valorization, and explored the applicability of CM-derived biochar (CMB) as an environmental medium for the adsorptive removal of sulfamethoxazole (SMZ). CM pyrolysis was conducted under two atmospheric conditions (N2 and CO2), and the pyrogenic products were quantified and characterized. Real-time syngas monitoring revealed that CO2 enhanced CO generation from the CM, leading to the formation of a highly porous carbon structure in the produced biochar (CMBCO2). The adsorptive removal of SMZ by CMBCO2 was highly dependent on the pH conditions. The adsorption kinetics of SMZ onto CMBCO2 reached equilibrium within 540 min, following a pseudo-second-order model. The SMZ adsorption isotherms fit the Langmuir-Freundlich model, highlighting the importance of chemisorption in the adsorption process. X-ray photoelectron spectroscopy revealed that SMZ was adsorbed by non-electrostatic mechanisms, including hydrogen bonding, Lewis acid-base interactions, surface complexation, and π–π electron-donor acceptor interactions. This study presents an exemplary strategy for converting livestock waste into valuable resources, enabling the harvesting of energy resources and the production of treatment media for environmental remediation.Keywords: Livestock manure; Waste valorization; Pyrolysis; Adsorption; Antibiotic; SulfamethoxazoleDOI: https://doi.org/10.1016/j.chemosphere.2024.143493

Journal: Biotechnology AdvancesAuthors: Jung-Hun Kim, Minyoung Kim, Gyeongnam Park, Eunji Kim, Hocheol Song, Sungyup Jung, Young-Kwon Park, Yiu Fai Tsang, Jechan Lee, Eilhann E KwonAbstract:​In response to address the climate crisis, there has been a growing focus on substituting conventional refinery-derived products with those derived from biorefineries. The utilization of lipids as primary materials or intermediates for the synthesis of chemicals and fuels, which are integral to the existing chemical and petrochemical industries, is a key step in this transition. This review provides a comprehensive overview of the production of sustainable chemicals (acids and alcohols), biopolymers, and fuels (including gasoline, kerosene, biodiesel, and heavy fuel oil) from lipids derived from terrestrial and algal biomass. The production of chemicals from lipids involves diverse methods, including polymerization, epoxidation, and separation/purification. Additionally, the transformation of lipids into biofuels can be achieved through processes such as catalytic cracking, hydroprocessing, and transesterification. This review also suggests future research directions that further advance the lipid valorization processes, including enhancement of catalyst durability at harsh conditions, development of deoxygenation process with low H2 consumption, investigation of precise separation of target compounds, increase in lipid accumulation in algal biomass, and development of methods that utilize residues and byproducts generated during lipid extraction and conversion.Keywords: Sustainability; Carbon neutrality; Circular economy; Biorefinery; BiochemicalDOI: https://doi.org/10.1016/j.biotechadv.2024.108418

Journal: International Journal of Energy ResearchAuthors: Sangyoon Lee, Minyoung Kim, Jee Young Kim, Hocheol Song, In-Hyun Nam, Eilhann E. KwonAbstract:Synthetic textiles such as polyesters are essential for daily life. However, large-scale production generates large amounts of waste. This study introduces a new approach for valorising polyester textile waste (PTW) by transforming it into a catalyst for biodiesel production via pyrolysis. Specifically, a metal/carbon composite (PTW + steel slag [SS] composite—PSC) with enhanced catalytic properties was prepared by pyrolysing PTW with SS. The alkaline metals in SS facilitate the carbonisation of PTW via decarboxylation, resulting in a PSC rich in carbon, iron, and alkaline compounds. This composite featured mesopores that were larger than the micropores (MPs) typically found in PTW char. The use of porous material (silica) in thermally induced transesterification has been proven to be an efficient method for biodiesel production, achieving a yield of 97.20 wt.% in 1 min (faster than the 93.82 wt.% yields in 60 min observed from conventional alkali-catalysed transesterification). However, the high reaction temperature (≥ 360°C) poses economic/technical challenges. To overcome this, PSC has been employed as a catalyst in thermally induced transesterification, leveraging its mesoporous structure and high alkaline content, particularly calcium oxide. The PSC achieved a biodiesel yield of 98.10 wt.% at a markedly lower reaction temperature of 120°C within 1 min. This performance was not attainable using silica or PTW char under similar conversion conditions. These findings highlight the potential of PSC produced through the pyrolysis of PTW and SS as effective catalysts for biodiesel production. This process is a promising strategy for converting waste into valuable resources and mitigating the environmental impacts associated with polyester waste.DOI: https://doi.org/10.1155/2024/1925113​

Journal: Catalysis Science & TechnologyAuthors: Mohammed Sifat, Michal Luchowski, Amol Pophali, Wenhui Jiang, Yunfan Lu, Byeongseok Kim, Gihan Kwon, Kwangsuk Yoon, Jihun Kim, Kwangjin An, Sang Eun Shim, Hocheol Song, Tae Jin KimAbstract:Although cerium oxide (CeO2) is widely used as a catalyst support, its limited defect sites and surface oxygen vacancy/mobility should be improved. The incorporation of zirconium (Zr) in the cerium (Ce) lattice is shown to increase the number of oxygen vacancies and improve catalytic activity. Using a fixed surface density (SD) of copper (∼2.3 Cu atoms per nm2) as a surface species, the role of the support (CeyZr1−yO2 (y = 1.0, 0.9, 0.6, 0.5, and 0.0)) and defect site effects in the CO oxidation reaction was investigated. Spectroscopic (e.g., Raman, XRD, XPS) and microscopic (e.g., SEM-EDX, HR-TEM) characterization techniques were applied to evaluate the defect sites, crystallite size, lattice parameters, chemical composition, oxidation states of elements and microstructure of the catalysts. The CO oxidation reaction with varied CO:O2 ratios (1:5, 1:1, and 1:0.5 (stoichiometric)) was used as a model reaction to describe the relationship between the structure and the catalytic performance of each catalyst. Based on the characterization results of CeyZr1−yO2 materials, the addition of Zr causes physical and chemical changes to the overall material. The inclusion of Zr into the structure of CeO2 decreased the overall lattice parameter of the catalyst and increased the number of defect sites. The prepared catalysts were able to reach complete CO conversion (∼100%) at low temperature conditions (<200 °C), each showing varied reaction activity. The difference in CO oxidation activity was then analyzed and related to the structure, wherein Cu loading, surface oxygen vacancies, reduction–oxidation ability, CuOx–support interaction and oxygen mobility in the catalyst were the crucial descriptors.DOI: https://doi.org/10.1039/D4CY01012D

​Journal: Catalysis Science & Technology​Authors: Kyung-Min Lee, Byeongseok Kim, Juwon Lee, Gihan Kwon, Kwangsuk Yoon, Hocheol Song, Kyung Hoon Min, Sang Eun Shim, Sungwon Hwang, Taejin KimAbstract:Multiwalled boron nitride nanotube (BNNT), as a catalyst support, has become one of the promising materials due to its high oxidation resistance and thermal stability. In this work, ruthenium (Ru) supported on BNNT catalysts with different metal loadings and treatment conditions was investigated for CO oxidation as a model reaction. To understand the physicochemical properties of the prepared samples, a suite of techniques, including FTIR, UV-Raman, SEM, TEM, and XPS, was utilized. The results showed that the RuOx species were located on both the interior and the exterior surfaces of the BNNT, and an increase in metal loading led to increased active sites. 1 wt% RuOx/BNNT (oxidized) exhibited better catalytic activity than 1 wt% Ru/BNNT (reduced), indicating that treatment conditions significantly affect the catalytic properties. Reaction conditions, such as GHSV and the O2/CO ratio, were varied to further investigate the external mass transfer limitations and reaction mechanism of the 1 wt% RuOx/BNNT catalyst. The peculiar tubular morphology of the BNNT resulted in negligible external mass transfer limitation, and the catalyst might primarily follow the Eley–Rideal (ER) mechanism over the Langmuir–Hinshelwood (LH) mechanism.DOI: https://doi.org/10.1039/D4CY00945B

​Journal: Journal of Analytical and Applied Pyrolysis​Authors: Gihoon Kwon, Dong-Wan Cho, Kwangsuk Yoon, Eunji Kim, Jaewon Lee, Hocheol SongAbstract:The continuous growth of the global population and industries has led to the mass generation of plastic and industrial waste, posing significant environmental challenges due to their incompatibility with conventional waste management practices. This study investigates the thermochemical conversion of plastic (nylon-6) and industrial waste (red mud) into value-added products, presenting a waste-to-resource conversion strategy. Nylon-6 and red mud were co-pyrolyzed, resulting in a metal-carbon composite characterized as porous N-doped graphitic carbon with embedded Fe0 particles. Application of the composite to an amaranth solution demonstrated its ability to activate persulfate, facilitating amaranth oxidation at a rate (kobs = 1.78 min−1) significantly higher than other Fe-based catalysts. Quenching experiments verified the generation of OH· and SO4·- radicals during activation, with the latter playing a dominant role in amaranth degradation. The composite exhibited robust reusability, maintaining an amaranth removal efficiency of >80 % after five reaction cycles. Additionally, red mud significantly enhanced syngas (H2 and CO) generation from nylon-6, suggesting a catalytic effect. In conclusion, the proposed thermochemical approach offers a viable method for converting waste materials into valuable products, including environmental catalysts and gas fuels. Keywords: N-doped graphic carbon; Co-pyrolysis; Red mud; Plastic valorization; Persulfate activationDOI: https://doi.org/10.1016/j.jaap.2024.106619