The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
Eilhann E Kwon - One of the best experts on this subject based on the ideXlab platform.
-
one step fabrication of carbon supported cobalt pentlandite co9s8 via the thermolysis of lignin and co3o4
Journal of CO 2 Utilization, 2018Co-Authors: Gihoon Kwon, Eilhann E Kwon, Dongwan Cho, Daniel C W Tsang, Hocheol SongAbstract:Abstract This work proposed a new method for one step fabrication of carbon supported (biochar) Co9S8 composite via the Thermo-Chemical Process of cobalt oxide (Co3O4) and lignin under CO2 atmosphere. A series of pyrolysis were conducted in N2 and CO2 environment, and their thermal degradation behaviors were characterized. The thermogravimetric analysis tests revealed that CO2 did not affect physical aspects of the thermal degradation. However, the influence of CO2 on chemical aspects governing the thermal degradation mechanisms was apparent. As an example of it, carbon supported (biochar) Co9S8 composite was only generated in CO2 environment. The surface morphology and structural matrix of biochar generated from CO2 environment was characterized using various spectroscopic instruments, which confirmed the formation of Co9S8. The formation of Co9S8 was highly affected by the pyrolytic parameters such as temperature and duration for isothermal run. Furthermore, use of CO2 as the reaction medium provided an effective way for modifying pore structure of biochar. More importantly, the formation of highly porous structure and Co9S8 in the presence of CO2 imparted strong catalytic capability. The reaction kinetics of p-nitrophenol (PNP) reduction using CO2-700 °C and CO2-760 °C biochar was 9 × 10−3 and 18 × 10−3 s−1, respectively, of which performance was superior to other catalytic materials in the literature. Lastly, the successive PNP reduction tests revealed the invulnerable catalytic capability up to 10 PNP reduction cycles. Thus, all experimental findings in this study suggests that Co9S8 could be synthesize from the waste materials and CO2. Moreover, Co9S8 could be employed as an effective catalyst in the environmental applications.
-
use of carbon dioxide as a reaction medium in the thermo chemical Process for the enhanced generation of syngas and tuning adsorption ability of biochar
Energy Conversion and Management, 2016Co-Authors: Eilhann E Kwon, Hocheol SongAbstract:Abstract This study mechanistically investigated the influences of CO 2 on syngas (H 2 and CO) production during Thermo-Chemical conversion of red seaweed, and further explored the possible utility of the produced biochar as a medium for adsorption of inorganic/organic contaminants in aqueous phase. In order to elucidate the key roles of CO 2 in the Thermo-Chemical Process, the composition analysis of syngas and the qualitative analysis of pyrolytic oil were conducted and compared with those in pyrolysis in N 2 condition. Pyrolysis of red seaweed in the presence of CO 2 led to the enhanced generation of syngas at the entire experimental temperatures. For example, the ratio of CO to H 2 in the presence of CO 2 at 620 °C was enhanced by ∼400%, as compared to the case in N 2 . This enhanced generation of syngas resulted in significant pyrolytic oil reduction by ∼70% at 620 °C via the unknown reactions between VOCs and CO 2 . In addition, biochar generated in the CO 2 environment exhibited comparatively higher surface area (61 m 2 g −1 ) and more porous structure. The morphological modification induced by CO 2 provided the favorable condition for removal of methylene blue from the aqueous phase. Thus, this study experimentally demonstrated that exploiting CO 2 as a reaction medium would provide an attractive option for the enhanced generation of syngas and the tuned adsorption capability of biochar.
-
enhanced thermal cracking of vocs evolved from the thermal degradation of lignin using co2
Energy, 2016Co-Authors: Jieun Kim, Kihyun Kim, Eilhann E KwonAbstract:This work offers a mechanistic investigation of the thermal degradation of lignin in the recovery of energy from biomass waste (i.e., lignin). Particularly, this work describes the influence of CO2 in the pyrolysis Process since pyrolysis Process has been known as an intermediate step for gasification. This work experimentally justifies the effectiveness of the influence of CO2 in pyrolysis of lignin at temperatures higher than ∼550 °C. Our GC/TOF-MS analysis of pyrolytic oil obtained at temperature lower than ∼500 °C indicated the thermal degradation of lignin via the thermal bond dissociation of phenolic compounds from the macromolecule of lignin: these phenolic compounds identified in the N2 and CO2 environment were nearly identical. The unknown reaction induced by CO2 at temperatures higher than ∼550 °C simultaneously and independently occurred with dehydrogenation of VOCs (volatile organic carbons), which significantly enhanced the generation of CO via providing the additional source of C and O. Thus, this work shows that the ratio of CO to H2 was significantly enhanced in the presence of CO2, the enhancement of which reached up to ∼1000% at 650 °C as compared to the case in N2. In order to enhance the identified influence of CO2, the porous material (i.e., activated alumina) was used in pyrolysis of lignin. Our experimental work shows that employing the porous material was indeed effective to enhance the generation of syngas. This observation indirectly implied not only that employing porous materials could enhance the generation of pyrolytic gases, but also that the reaction rate induced by CO2 would be very fast. In summary, this study experimentally justifies the fact that exploiting CO2 as reaction medium enhances not only the thermal efficiency of the Thermo-Chemical Process, but also the sustainability of biomass-derived fuel via achieving the virtuous circle of carbon.
-
pseudo catalytic transformation of volatile fatty acids into fatty acid methyl esters
Bioresource Technology, 2016Co-Authors: Jongmin Jung, Eilhann E KwonAbstract:Abstract Instead of anaerobic digestion of biodegradable wastes for producing methane, this work introduced the transformation of acidogenesis products (VFAs) into fatty acid methyl esters (FAMEs) to validate the feasible production of short-chained fatty alcohols via hydrogenation of FAMEs. In particular, among VFAs, this work mainly described the mechanistic explanations for transforming butyric acid into butyric acid methyl ester as a case study. Unlike the conventional esterification Process (conversion efficiency of ∼94%), the newly introduced esterification under the presence of porous materials via the Thermo-Chemical Process reached up to ∼99.5%. Furthermore, the newly introduced esterification via the Thermo-Chemical pathway in this work showed extremely high tolerance of impurities: the conversion efficiency under the presence of impurities reached up to ∼99 ± 0.3%; thus, the inhibition behaviors attributed from the impurities used for the experimental work were negligible.
-
carbon dioxide assisted sustainability enhancement of pyrolysis of waste biomass a case study with spent coffee ground
Bioresource Technology, 2015Co-Authors: Dongwan Cho, Seongheon Cho, Hocheol Song, Eilhann E KwonAbstract:This work mainly presents the influence of CO2 as a reaction medium in the Thermo-Chemical Process (pyrolysis) of waste biomass. Our experimental work mechanistically validated two key roles of CO2 in pyrolysis of biomass. For example, CO2 expedited the thermal cracking of volatile organic compounds (VOCs) evolved from the thermal degradation of spent coffee ground (SCG) and reacted with VOCs. This enhanced thermal cracking behavior and reaction triggered by CO2 directly led to the enhanced generation of CO (∼3000%) in the presence of CO2. As a result, this identified influence of CO2 also directly led to the substantial decrease (∼40–60%) of the condensable hydrocarbons (tar). Finally, the morphologic change of biochar was distinctive in the presence of CO2. Therefore, a series of the adsorption experiments with dye were conducted to preliminary explore the physico-chemical properties of biochar induced by CO2.
Hocheol Song - One of the best experts on this subject based on the ideXlab platform.
-
one step fabrication of carbon supported cobalt pentlandite co9s8 via the thermolysis of lignin and co3o4
Journal of CO 2 Utilization, 2018Co-Authors: Gihoon Kwon, Eilhann E Kwon, Dongwan Cho, Daniel C W Tsang, Hocheol SongAbstract:Abstract This work proposed a new method for one step fabrication of carbon supported (biochar) Co9S8 composite via the Thermo-Chemical Process of cobalt oxide (Co3O4) and lignin under CO2 atmosphere. A series of pyrolysis were conducted in N2 and CO2 environment, and their thermal degradation behaviors were characterized. The thermogravimetric analysis tests revealed that CO2 did not affect physical aspects of the thermal degradation. However, the influence of CO2 on chemical aspects governing the thermal degradation mechanisms was apparent. As an example of it, carbon supported (biochar) Co9S8 composite was only generated in CO2 environment. The surface morphology and structural matrix of biochar generated from CO2 environment was characterized using various spectroscopic instruments, which confirmed the formation of Co9S8. The formation of Co9S8 was highly affected by the pyrolytic parameters such as temperature and duration for isothermal run. Furthermore, use of CO2 as the reaction medium provided an effective way for modifying pore structure of biochar. More importantly, the formation of highly porous structure and Co9S8 in the presence of CO2 imparted strong catalytic capability. The reaction kinetics of p-nitrophenol (PNP) reduction using CO2-700 °C and CO2-760 °C biochar was 9 × 10−3 and 18 × 10−3 s−1, respectively, of which performance was superior to other catalytic materials in the literature. Lastly, the successive PNP reduction tests revealed the invulnerable catalytic capability up to 10 PNP reduction cycles. Thus, all experimental findings in this study suggests that Co9S8 could be synthesize from the waste materials and CO2. Moreover, Co9S8 could be employed as an effective catalyst in the environmental applications.
-
use of carbon dioxide as a reaction medium in the thermo chemical Process for the enhanced generation of syngas and tuning adsorption ability of biochar
Energy Conversion and Management, 2016Co-Authors: Eilhann E Kwon, Hocheol SongAbstract:Abstract This study mechanistically investigated the influences of CO 2 on syngas (H 2 and CO) production during Thermo-Chemical conversion of red seaweed, and further explored the possible utility of the produced biochar as a medium for adsorption of inorganic/organic contaminants in aqueous phase. In order to elucidate the key roles of CO 2 in the Thermo-Chemical Process, the composition analysis of syngas and the qualitative analysis of pyrolytic oil were conducted and compared with those in pyrolysis in N 2 condition. Pyrolysis of red seaweed in the presence of CO 2 led to the enhanced generation of syngas at the entire experimental temperatures. For example, the ratio of CO to H 2 in the presence of CO 2 at 620 °C was enhanced by ∼400%, as compared to the case in N 2 . This enhanced generation of syngas resulted in significant pyrolytic oil reduction by ∼70% at 620 °C via the unknown reactions between VOCs and CO 2 . In addition, biochar generated in the CO 2 environment exhibited comparatively higher surface area (61 m 2 g −1 ) and more porous structure. The morphological modification induced by CO 2 provided the favorable condition for removal of methylene blue from the aqueous phase. Thus, this study experimentally demonstrated that exploiting CO 2 as a reaction medium would provide an attractive option for the enhanced generation of syngas and the tuned adsorption capability of biochar.
-
carbon dioxide assisted sustainability enhancement of pyrolysis of waste biomass a case study with spent coffee ground
Bioresource Technology, 2015Co-Authors: Dongwan Cho, Seongheon Cho, Hocheol Song, Eilhann E KwonAbstract:This work mainly presents the influence of CO2 as a reaction medium in the Thermo-Chemical Process (pyrolysis) of waste biomass. Our experimental work mechanistically validated two key roles of CO2 in pyrolysis of biomass. For example, CO2 expedited the thermal cracking of volatile organic compounds (VOCs) evolved from the thermal degradation of spent coffee ground (SCG) and reacted with VOCs. This enhanced thermal cracking behavior and reaction triggered by CO2 directly led to the enhanced generation of CO (∼3000%) in the presence of CO2. As a result, this identified influence of CO2 also directly led to the substantial decrease (∼40–60%) of the condensable hydrocarbons (tar). Finally, the morphologic change of biochar was distinctive in the presence of CO2. Therefore, a series of the adsorption experiments with dye were conducted to preliminary explore the physico-chemical properties of biochar induced by CO2.
Helmut Rechberger - One of the best experts on this subject based on the ideXlab platform.
-
comparative goal oriented assessment of conventional and alternative sewage sludge treatment options
Waste Management, 2010Co-Authors: Jakob Lederer, Helmut RechbergerAbstract:Phosphorous (P) is a limited and non-substitutable resource. Sewage sludge contains significant amounts of P and is therefore a widely applied fertilizer. Due to its organic and inorganic contaminants, sewage sludge is also combusted in industrial facilities as well as in waste incinerators. This study compares five common methods and one novel alternative based on a Thermo-Chemical Process to treat and dispose of sewage sludge with regard to environmental impact, resource recovery, and materials dissipation. The comparison is based on material flow analysis, energy balances, selected LCA impact analysis, and statistical entropy analysis. This work shows that the novel technology combines both advantages of the established practices: organic and inorganic pollutants are either destroyed or removed from the P containing material, and the P returned to the soil exhibits high plant-availability. The novel method also has low emissions. The additional energy requirements should be reduced. However, with regards to sewage sludge P recovery is more important than energy recovery.
Mustafa Balat - One of the best experts on this subject based on the ideXlab platform.
-
main routes for the thermo conversion of biomass into fuels and chemicals part 2 gasification systems
Energy Conversion and Management, 2009Co-Authors: Mustafa Balat, Elif Kirtay, Havva BalatAbstract:Abstract Gasification as a Thermo-Chemical Process is defined and limited to combustion and pyrolysis. The gasification of biomass is a thermal treatment, which results in a high production of gaseous products and small quantities of char and ash. The solid phase usually presents a carbon content higher than 76%, which makes it possible to use it directly for industrial purposes. The gaseous products can be burned to generate heat or electricity, or they can potentially be used in the synthesis of liquid transportation fuels, H 2 , or chemicals. On the other hand, the liquid phase can be used as fuel in boilers, gas turbines or diesel engines, both for heat or electric power generation. However, the main purpose of biomass gasification is the production of low- or medium heating value gas which can be used as fuel gas in an internal combustion engine for power production. In addition to limiting applications and often compounding environmental problems, these technologies are an inefficient source of usable energy.
Jakob Lederer - One of the best experts on this subject based on the ideXlab platform.
-
comparative goal oriented assessment of conventional and alternative sewage sludge treatment options
Waste Management, 2010Co-Authors: Jakob Lederer, Helmut RechbergerAbstract:Phosphorous (P) is a limited and non-substitutable resource. Sewage sludge contains significant amounts of P and is therefore a widely applied fertilizer. Due to its organic and inorganic contaminants, sewage sludge is also combusted in industrial facilities as well as in waste incinerators. This study compares five common methods and one novel alternative based on a Thermo-Chemical Process to treat and dispose of sewage sludge with regard to environmental impact, resource recovery, and materials dissipation. The comparison is based on material flow analysis, energy balances, selected LCA impact analysis, and statistical entropy analysis. This work shows that the novel technology combines both advantages of the established practices: organic and inorganic pollutants are either destroyed or removed from the P containing material, and the P returned to the soil exhibits high plant-availability. The novel method also has low emissions. The additional energy requirements should be reduced. However, with regards to sewage sludge P recovery is more important than energy recovery.