• Journal of Energy Engineering
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• v.20 no.4
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• pp.298-302
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• 2011

In this study, Catalytic reforming with vapor and biomass gasification was simultaneously performed in a same fixed bed reactor at $600-800^{\circ}C$. Light gases were produced from reformation of the tar (fuel gases) in biomass gasification by using limonite and dolomite, as catalysts. Hydrogen and carbon dioxide are main components in light gases. Hydrogen yields increased with temperature increasing in the range of $650-800^{\circ}C$, because the water shift reaction was promoted by catalyst. The yield of hydrogen gas was increased about 160% under catalyst with the mixture of limonite and dolomite comparing to limonite only.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1997.10a
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• pp.54-58
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• 1997

• Clean Technology
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• v.18 no.4
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• pp.426-431
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• 2012

Carbon-rich coal can be utilized as a fuel for direct carbon fuel cell (DCFC). However, left-behind ash after the electrochemical oxidation may hinder the electrochemical reactions. In this study, we produced ash-free coal (AFC) by thermal extraction and then tested it as a fuel for DCFC. DCFC was built based on solid oxide electrolyte and the electrochemical performance of AFC mixed with $K_2CO_3$ was compared with AFC only. Significantly enhanced power density was found by catalytic steam gasification of AFC. However, an increase of the power density by catalytic pyrolysis was negligible. This result indicated that a catalyst activated the steam gasification reactions, producing much more $H_2$ and thus increasing the power density, compared to AFC only. Results of a quantitative analysis showed much improved kinetics in AFC with $K_2CO_3$ in agreement with DCFC results. A secondary phase of potassium on yttria-stabilized zirconia (YSZ) surface was observed after the cell operation. This probably caused poor long-term behavior of AFC with $K_2CO_3$. A thin YSZ (30 ${\mu}m$ thick) was found to be higher in the power density than 0.9 mm of YSZ.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.653-662
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• 2015

In general, the coal gasification has to be operated under high temperature ($1300{\sim}1400^{\circ}C$) and pressure (30~40 bar). However, to keep this conditions, it needs unnecessary and excessive energy. In this work, to reduce the temperature of process, alkali catalysts such as $K_2CO_3$ and $Na_2CO_3$ were added into Cyprus coal. We investigated the kinetic of Cyprus char-$CO_2$ gasification. To determine the gasification conditions, the coal (with and without catalysts) gasified with fixed variables (catalyst loading, catalytic effects of $Na_2CO_3$ and $K_2CO_3$, temperatures) by using TGA. When catalysts are added by physical mixing method into Cyprus coal the reaction rate of coal added 7 wt% $Na_2CO_3$ is faster than raw coal for Cyprus char-$CO_2$ gasification. The activation energy of coal added 7 wt% $Na_2CO_3$ was calculated as 63 kJ/mol which was lower than raw char. It indicates that $Na_2CO_3$ can improve the reactivity of char-$CO_2$ gasification.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.355-356
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• 2014

Catalytic steam reforming of tar produced from biomass gasification was conducted using several Ni-based catalysts. K and Mn were used as a promoter over $Ni/Ru/Al_2O_3$ catalyst. The pellet and monolith type catalysts were prepared and applied to lab and bench-scale biomass gasification system. The $Ni/Ru-K/Al_2O_3$ catalyst shown higher performance than $Ni/Ru-Mn/Al_2O_3$ catalyst at low temperature range.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.33-36
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• 2014

Gasification of biomass produces syngas containing CO, $H_2$ and/or $CH_4$, which can then be converted into energy or value-added fuels. One of key issues for efficient gasification is to minimize tar concentration in the syngas for use in a final conversion device such as gas engine. This study investigated the decomposition of primary tar by catalytic cracking using char as catalyst, of which the feature can be integrated into a fixed bed gasifier design. The pyrolysis vapor containing tar from pyrolysis of wood at $500^{\circ}C$ was passed through a reactor filled with or without char at $800^{\circ}C$ for a residence time of 1, 3 or 5 sec. Then, the condensable vapor (water and tar) and gases were analyzed for the yields and elemental composition. Four types of char particles with different microscopic surface area and pore size distribution: wood, paddy straw, palm kernel shell and activated carbon. The results were analyzed for the mass and carbon yields of tar and the composition of product gases to conclude the effects of char types and residence time.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.247-250
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• 2008

Biomass gasification is a promising technology for producing a fuel gas which is useful for power generation systems. In biomass gasification processes, tar formation often causes some problems such as pipeline plugging. Thus, proper tar treatment is necessary. So far, nickel (Ni)-based catalysts have been intensively studied for the catalytic tar removal. However, the deactivation of Ni-based catalysts takes place because of coke deposition and sintering of Ni metal particles. To overcome these problems, we have been using ruthenium (Ru)-based catalyst for tar removal. It is reported by Okada et al., that a Ru/$Al_2O_3$ catalyst is very effective for preventing the carbon deposition during the steam reforming of hydrocarbons. Also, this catalyst is more active than the Ni-based catalyst at a low steam to carbon ratio (S/C). Benzene was used for the tar model compound because it is the main constituent of biomass tar and also because it represents a stable aromatic structure apparent in tar formed in biomass gasification processes. The steam reforming process transforms hydrocarbons into gaseous mixtures constituted of carbon dioxide ($CO_2$), carbon monoxide (CO), methane ($CH_4$) and hydrogen ($H_2$).

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.544-552
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• 2014

In this study, We have investigated the kinetics on the char-$CO_2$ gasification reaction. Thermogravimetric analysis (TGA) experiments were carried out for char-$CO_2$ catalytic gasification of an Indonesian Roto lignite. $Na_2CO_3$, $K_2CO_3$, $CaCO_3$ and dolomite were selected as catalyst which was physical mixed with coal. The char-$CO_2$ gasification reaction showed rapid an increase of carbon conversion rate at 60 vol% $CO_2$ and 7 wt% $Na_2CO_3$ mixed with coal. At the isothermal conditions range from $750^{\circ}C$ to $900^{\circ}C$, the carbon conversion rates increased as the temperature increased. Three kinetic models for gas-solid reaction including the shrinking core model (SCM), volumetric reaction model (VRM) and modified volumetric reaction model (MVRM) were applied to the experimental data against the measured kinetic data. The gasification kinetics were suitably described by the MVRM model for the Roto lignite. The activation energies for each char mixed with $Na_2CO_3$ and $K_2CO_3$ were found a 67.03~77.09 kJ/mol and 53.14~67.99 kJ/mol.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.209-213
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• 2008

The fixed bed gasification reactor with 1 m hight and 10.2 cm diameter was utilized for the hydrogen production from biomass wastes. Lauan sawdust was used for non-catalytic and catalytic gasification reaction as a sample in the fixed bed reactor. The fixed bed temperature and catalyst are the major variables affecting the process operation. Thus, the effect of fixed bed temperature and the catalysts on gas composition were studied at the temperature range from $400^{\circ}C$ to $700^{\circ}C$. The yield of hydrogen was increased at higher temperature in the fixed bed reaction. Fractions of hydrogen, carbon monoxide and methane gas in the product gas increased when sodium carbonate ($Na_2CO_3$) and potassium carbonate ($K_2CO_3$) catalysts were used. Furthermore, sodium carbonate catalyst was more effective to obtain higher hydrogen yield compared to potassium carbonate catalyst.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.533-536
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• 2009

The gasification technology is a very flexible and versatile technology to produce a wide variety products such as electricity, steam, hydrogen, Fisher-Tropsch(FT) diesels, Dimethyl Ether(DME), methanol and SNG(Synthetic Natural Gas) with near-zero pollutant emissions. Gasification converts coal and other low-grade feedstocks such as biomass, wastes, residual oil, petroleum coke, etc. to a very clean and usable syngas. Syngas is produced from gasifier including CO, $H_2$, $CO_2$, $N_2$, particulates and smaller quantities of $CH_4$, $NH_3$, $H_2S$, COS and etc. After removing pollutants, syngas can be variously used in energy and environment fields. The pilot-scale coal gasification system has been operated since 1994 at Ajou University in Suwon, Korea. The pilot-scale gasification facility consists of the coal gasifier, the hot gas filtering system, and the acid gas removal (AGR) system. The acid gas such as $H_2S$ and COS is removed in the AGR system before generating electricity by gas engine and producing chemicals like Di-methyl Ether(DME) in the catalytic reactor. The designed operation temperature and pressure of the $H_2S$ removal system are below $50^{\circ}C$ and 8 kg/$cm^2$. The iron chelate solution is used as an absorbent. $H_2S$ is removed below 0.1 ppm in the H2S removal system.