• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.8-14
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• 2015

In this study, the model biomass was used for hydrogen production by supercritical water gasification (SCWG). Model biomasses were glycerol, glycine, lignin and cellulose. The feed concentration was set to 1 wt%. Experiments were conducted in a reactor at $440^{\circ}C$ and above 26.3 MPa for 30 min. The effects of catalysts such as alkali metal salt ($K_2CO_3$ and $Na_2CO_3$) and transition metal salts ($Ni(NO_3)_2$, $Fe(NO_3)_3$ and $Mn(NO_3)_2$) on the gasification were systematically investigated. No tar or coke was observed in all experiments. The results showed that the gasification efficiency increased with various catalysts. For the cellulose and glycerol, all catalysts were effective for the promoted $H_2$ production compared with no catalyst. The significant decrease of $H_2$ production compared with no catalyst was observed with $Na_2CO_3$ and $Fe(NO_3)_3$ for glycine and lignin. respectively. The highest H2 production, 1.24 mmol was obtained for glycerol-SCWG with $Mn(NO_3)_2$. Conclusively, the addition of $Mn(NO_3)_2$ enhanced all model biomass gasification efficiency and increased the hydrogen production promoting the supercritical water reaction.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.10
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• pp.704-710
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• 2014

Biomass is considered an alternative energy which can solve an greenhouse gas problem like $CO_2$ which is a major contributor to global warming. The biomass can be converted to various energy sources through thermochemical conversion. In this study, a continuous gasifier was engineered for a wood biomass gasification. The biomass was used a waste wood. The experiments of $CO_2$ gasification were achieved as the gasification temperature, moisture content and input $CO_2$ concentration. The results showed that the yield of producer gas increased with an increasing the gasification temperature. The amount of the light tar increased due to the decomposition of gravimetric tar by the thermal cracking, and the char was confirmed pore development through the SEM analysis. The CO concentration was increased with an increased input $CO_2$ concentration from Boudouard reaction. Through the parametric screening studies, the hydrogen and carbon monoxide concentration were 32.91% and 48.33% at the optimal conditions of this test rig.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.286-290
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• 2011

Syngas was produced out of pellet refuse derived fuel (RDF) produced from an RDF production facility of W city, Korea. A two-stage gasification system was developed to use the RDF char as an auxiliary heat source for gasification reaction. The composition and heating value of syngas as well as the heating value of residual product (char) were measured at a different residence time to investigate the optimal operating condition of the two-stage gasification system for syngas production. The optimal char residence time to minimize the energy cost due to an external heat source supply was also deduced.

• Clean Technology
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• v.20 no.3
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• pp.218-225
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• 2014

Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. In this work, the gasification behavior of ash-free coal (AFC) was compared with that of the parent raw coal. In order to modify the gasification conditions, the raw coal gasified with fixed variables (water supply, space velocity, temperature, catalysts) in a fixed bed reactor. When catalysts are added by physical mixing method with coal, $K_2CO_3$ was the most effective additives for steam gasification of coal. However, the activity of ash-free coal (AFC) was much less reactive than raw coal due to high temperature extraction in a 1-methylnaphthalene under 30bar at $370^{\circ}C$ for 1 h, almost removed oxygen functional groups, and increased carbonization. The addition of $K_2CO_3$ in AFC achieved higher conversion rate at low temperature ($700^{\circ}C$). At that time, the molar ratio of gases ($H_2/CO$ and $CO_2/CO$) was increased because of water-gas shift reaction (WGSR) by addition of catalysts. This shows that catalytic steam gasification of AFCs is achievable for economic improvement of gasification process at mild temperature.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.107-107
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• 2010

Hydrogen is an alternative fuel for the future energy which can reduce pollutants and greenhouse gases. Synthesis gas have played an important role of synthesizing the valuable chemical compound, for example methanol, DME and GTL chemicals. Renewable biomass feedstocks can be potentially used for fuels and chemical production. Current thermal processing techniques such as fast pyrolysis, slow pyrolysis, and gasification tend to generate products with a large slate of compounds. Lignocellulose feedstocks such as forest residues are promising for the production of bio-oil and synthesis gas. Pyrolysis and gasification was investigated using thermogravimetric analyzer (TGA) and bubbling fluidized bed gasification reactor to utilize forest woody biomass. Most of the materials decomposed between $320^{\circ}C$ and $380^{\circ}C$ at heating rates of $5{\sim}20^{\circ}C/min$ in thermogravimetric analysis. Bubbling fluidized bed reactor were use to study gasification characteristics, and the effects of reaction temperature, residence time and feedstocks on gas yields and selectivities were investigated. With increasing temperature from $750^{\circ}C$ to $850^{\circ}C$, the yield of char decreased, whereas the yield of gas increased. The gaseous products consisted of mostly CO, CO2, H2 and a small fraction of C1-C4 hydrocarbons.

• Clean Technology
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• v.19 no.3
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• pp.333-341
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• 2013

This paper presents results on $CO_2$ gasification of 17 raw coals containing a wide range of volatile matter (21-57 wt%). The gasification is performed using a TGA under $CO_2$ and also under $N_2$ atmosphere. An amount of weight loss with increasing temperature is proportional to that of volatile matter in a coal under $N_2$ atmosphere. Reactivity of $CO_2$ gasification also increases with a content of volatile matter. However, the correlation is a little scattered. Oxygenated functional groups in a coal are generally reactive and therefore, an increase in O/C ratio leads to enhanced reactivity. However, $CO_2$ reactivity is affected by neither H/C ratio nor a content of ashes that possibly activate the gasification reaction. These findings are also applicable to steam coal gasification and the reactivity series are confirmed in the test at a fixed bed reactor.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.466-473
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• 2016

In this study, the experiments on optimal CO gas synthesis were conducted using low grade coal-$CO_2$ catalyst gasification reaction. The characteristics of generated CO gas were investigated using the chemical activation method of KOH, $K_2CO_3$, $Na_2CO_3$ catalysts with Kideco and Shewha coal. The preparation process has been optimized through the analysis of experimental variables such as ratio between activating chemical agents and coal, the flow rate of gas and reaction temperature during $CO_2$ conversion reaction. The produced CO gas was analysed by Gas Chromatography (GC). The 98.6% $CO_2$ conversion for Kideco coal mixed with 20 wt% $Na_2CO_3$ and 98.9% $CO_2$ conversion for Shenhua coal mixed with 20 wt% KOH were obtained at the conditions of $T=950^{\circ}C$ and $CO_2$ flow rate of 100 cc/min. Also, the low grade coal-$CO_2$ catalytic gasification reaction showed the CO selectivities(97.8 and 98.8 %) at the same feed ratio and reaction conditions.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.259-262
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• 2014

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.371-376
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• 2008

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.4
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• pp.340-346
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• 2013

Study on clean and efficient utilization technology for low rank coal with high moisture content is actively ongoing due to limited reserves of petroleum and of high grade coal and serious climate change caused by fossil fuel usage. In the present study, supercritical water gasification of low rank coal was performed. With increasing reaction temperature, content of combustible gases such as $H_2$ and $CH_4$ in the syngas increased while the $CO_2$ content decreased. As the reaction pressure increased from 210 to 300 bar, the $CO_2$ content in the syngas increased while the hydrocarbon gas content decreased. The $H_2$ and $CH_4$ content in the syngas increased slightly with pressure. With the addition of Pd, Pt, and Ru catalysts, it was possible to improve the production of $H_2$. Moreover, the increase of active metal content in the catalyst increased the $H_2$ productivity. The Ru catalyst shows the best performance for increasing the $H_2$ content in the syngas, while decreasing the $CO_2$ content.