Jung Min Sohn

Steam reforming of biomass gasification tar using benzene as a model compound over various Ni supported metal oxide catalysts

The steam reforming of benzene as a model compound of biomass gasification tar was carried out over various Ni/metal oxide catalysts. The effects of the support, temperature, Ni-precursor, Ni loading and reaction time were examined, and their catalytic performance was compared with that of a commercial Ni catalyst. Among the Ni/metal oxide catalysts used, 15 wt% Ni/CeO(2)(75%)-ZrO(2)(25%) showed the highest catalytic performance owing to its greater redox characteristics and increased surface area, irrespective of the reaction temperature. The catalytic activity of 15 wt% Ni/CeO(2)(75%)-ZrO(2)(25%) was higher than that of the commercial Ni catalyst. Moreover, the catalyst activity was retained due to its excellent resistance to coke deposition even after 5h. The Ni-precursor played a critical role in the catalytic activity. With the exception of nickel nitrate, all the Ni-precursors (chloride and sulfate) caused deactivation of the catalyst.

Influence of operation variables on fast pyrolysis of Miscanthus sinensis var. purpurascens.

Fast pyrolysis of Miscanthus was investigated in a bench-scale fluidized bed reactor for production of bio-oil. Process conditions were varied for temperature (350-550 degrees C), particle size (0.3-1.3mm), feed rate and gas flow rate. Pyrolysis temperature was the most influential parameter upon the yield and properties of bio-oil. The highest bio-oil yield of 69.2wt.% was observed at a temperature of 450 degrees C which corresponded to the end of the thermal composition of hemicellulose and cellulose. In the bio-oil, the water content was 34.5wt.%, and the main compounds in the organic fraction were phenolics and oxygenates. With increasing temperature, the amount of oxygenates in the bio-oil decreased gradually while that of water and aromatics increased rapidly. The bio-oil yield was not significantly affected by particle sizes or feed rates. The use of product gases as a fluidizing medium aided in increasing bio-oil yield.

Catalytic pyrolysis of waste rice husk over mesoporous materials

Catalytic fast pyrolysis of waste rice husk was carried out using pyrolysis-gas chromatography/mass spectrometry [Py-GC/MS]. Meso-MFI zeolite [Meso-MFI] was used as the catalyst. In addition, a 0.5-wt.% platinum [Pt] was ion-exchanged into Meso-MFI to examine the effect of Pt addition. Using a catalytic upgrading method, the activities of the catalysts were evaluated in terms of product composition and deoxygenation. The structure and acid site characteristics of the catalysts were analyzed by Brunauer-Emmett-Teller surface area measurement and NH3 temperature-programmed desorption analysis. Catalytic upgrading reduced the amount of oxygenates in the product vapor due to the cracking reaction of the catalysts. Levoglucosan, a polymeric oxygenate species, was completely decomposed without being detected. While the amount of heavy phenols was reduced by catalytic upgrading, the amount of light phenols was increased because of the catalytic cracking of heavy phenols into light phenols and aromatics. The amount of aromatics increased remarkably as a result of catalytic upgrading, which is attributed to the strong Brönsted acid sites and the shape selectivity of the Meso-MFI catalyst. The addition of Pt made the Meso-MFI catalyst even more active in deoxygenation and in the production of aromatics.

Bio-oil upgrading over Ga modified zeolites in a bubbling fluidized bed reactor

Abstract Catalytic upgrading of bio-oil was carried out over Ga modified ZSM-5 for the pyrolysis of sawdust in a bubbling fluidized bed reactor. Effect of gas velocity (U o /U mf ) on the yield of pyrolysis products was investigated. The maximum yield of oil products was found to be about 60% at the U o /U mf of 4.0. The yield of gas was increased as catalyst added. HZSM-5 shows the larger gas yield than Ga/HZSM- 5. When bio-oil was upgraded with HZSM-5 or Ga/HZSM-5, the amount of aromatics in product increased. Product yields over Ga/HZSM-5 shows higher amount of aromatic components such as benzene, toluene, xylene (BTX) than HZSM-5.

The Effect on the Steam Gasification Reaction of Low-Rank Coal Mixed with Waste Catalysts

We have investigated the kinetics and activity of waste catalysts for steam-lignite gasification. Waste catalysts I, II, III and reference were used and physical mixed with a coal. The gasification experiments were carried out with the low rank coal loaded with 1 wt% and 5 wt% catalyst at the temperature range from 700 to using thermobalance reactor. It was observed that the carbon conversion reached almost 100% regardless of the kinds of catalysts at . The shortest time to reach the designated conversion was obtained for 1 wt% waste catalyst II and 5 wt% at . The gasification reaction rate constant increased with increasing the temperature. Highest rate constant was obtained with at . The lowest activation energy was 69.42 kJ/mol for 5 wt% waste catalyst II. The waste catalyst had an influence on the reduction of activation energy.

Water gas shift reaction in a catalytic bubbling fluidized bed reactor

The water gas shift reaction in a catalytic bubbling fluidized bed reactor was investigated by using simulated syngas (40% H2, 40% CO and 20% CO2) for the pre-combustion CO2 capture and hydrogen production application. A commercial low temperature shift (LTS) catalyst with particle sizes of 200-300 μm was used to investigate the promotion effect by exchanging the fixed bed reaction with the fluidized bed reactor. The effects of the reactor temperature (180-400 °C), space velocity (800-4,800 cm3/h·g), and steam/CO ratio (1.0-2.5) on the CO conversion and syngas composition were determined, and the highest CO conversion was 86.8% at 300 °C with the LTS catalyst at a space velocity of 800 cm3/h·g and steam/CO ratio of 2.5. The experiments exhibited an improvement in activity and a conversion reached that given by equilibrium at temperatures over 300 °C. Also, the performance was much improved than that when a fixed bed system was used.

The Study on of Hydrogen Production Performance by Model Biomass-supercritical Water Gasification with Various Catalysts

>> 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 °C and above 26.3 MPa for 30 min. The effects of catalysts such as alkali metal salt (K2CO3 and Na2CO3) and transition metal salts (Ni(NO3)2, Fe(NO3)3 and Mn(NO3)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 H2 production compared with no catalyst. The significant decrease of H2 production compared with no catalyst was observed with Na2CO3 and Fe(NO3)3 for glycine and lignin. respectively. The highest H2 production, 1.24 mmol was obtained for glycerol-SCWG with Mn(NO3)2. Conclusively, the addition of Mn(NO3)2 enhanced all model biomass gasification efficiency and increased the hydrogen production promoting the supercritical water reaction.

The Study on the Catalytic Performance and Characterization of La0.9Sr0.1Cr0.7B0.3O3±δ (B=Mn, Ni, Fe, Ru) for High Temperature Water-gas Shift Reaction with Simuated Coal-derived Syngas

Abstract >> In this study, La 0.9 Sr 0.1 Cr 0.7 M 0.3 O 3±δ (M=Mn, Ru, Fe, Ni) were prepared by sol-gel method and water gas shift reaction with simulated coal–derived syngas between 400~650℃ was conducted to evaluate the catalyticactivity of prepared catalysts. Physico-chemical properties were characterized by XRD, BET, SEM-EDS and TPR.The formation of perovskite crystallite, LaCrO 3 was confirmed and the highest surface area was measured withLa 0.9 Sr 0.1 Cr 0.7 Mn 0.3 O 3±δ . Equilibrium conversion of CO above 550℃ was achieved except La 0.9 Sr 0.1 Cr 0.7 Fe 0.3 O 3±δ . and methanation reaction was carried out as side reaction of water gas shift reaction with La 0.9 Sr 0.1 Cr 0.7 Ni 0.3 O 3±δ and La 0.9 Sr 0.1 Cr 0.7 Ru 0.3 O 3±δ . Conclusively, La 0.9 Sr 0.1 Cr 0.7 Mn 0.3 O 3±δ was the most suitable catalyst of water gas shift reaction above 500℃ for CO conversion and hydrogen production. Key words : Water-gas shift reation(수성가스전환반응), CO conversion(CO 전환율), hydrogen(수소), perovskite(페로브스카이트)