• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1119-1126
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• 2007

Hydrogen gas and carbon nanotubes along with nanocarbon were produced from commercial natural gas using fixed bed catalyst reactor system. The maximum amount of carbon (491 g/g of catalyst) formation was achieved on 25% Ni, 3% Cu supported catalyst without formation of CO/CO2. Pure carbon nanotubes with length of 308 nm having balloon and horn type shapes were also formed at 673 K. Three sets of catalysts were prepared by varying the concentration of Ni in the first set, Cu concentration in the second set and doping with K in the third set to investigate the effect on stabilization of the catalyst and production of carbon nanotubes and hydrogen by copper and potassium doping. Particle size analysis revealed that most of the catalyst particles are in the range of 20-35 nm. All the catalysts were characterized using powder XRD, SEM/EDX, TPR, CHN, BET and CO-chemisorption. These studies indicate that surface geometry is modified electronically with the formation of different Ni, Cu and K phases, consequently, increasing the surface reactivity of the catalyst and in turn the Carbon nanotubes/H2 production. The addition of Cu and K enhances the catalyst dispersion with the increase in Ni loadings and maximum dispersion is achieved on 25% Ni: 3% Cu/Al catalyst. Clearly, the effect of particle size coupled with specific surface geometry on the production of hydrogen gas and carbon nanotubes prevails. Addition of K increases the catalyst stability with decrease in carbon formation, due to its interaction with Cu and Ni, masking Ni and Ni:Cu active sites.

• Clean Technology
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• v.27 no.1
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• pp.69-78
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• 2021

Vegetable oils, such as palm oil and cashew nut shell liquid (CNSL), are used as major raw materials for bio-diesel in transportation and bio-heavy oil in power generation in South Korea. However, due to the high unsaturation degree caused by hydrocarbon double bonds and a high content of oxygen originating from the presence of carboxylic acid, the range of applications as fuel oil is limited. In this study, hydrotreating to saturate unsaturated hydrocarbons and remove oxygen in mixed bio-oil containing 1/1 v/v% palm oil and CNSL on monometallic catalysts (Ni and Cu) and bimetallic catalysts (Ni-Zn, Ni-Fe, Ni-Cu Ni-Co, Ni-Pd, and Ni-Pt) was perform under mild conditions (T = 250 ~ 400 ℃, P = 5 ~ 80 bar and LHSV = 1 h-1). The addition of noble metals and transition metals to Ni showed synergistic effects to improve both hydrogenation (HYD) and hydrodeoxygenation (HDO) activities. The most promising catalyst was Ni-Cu/��-Al2O3, and in the wide range of the Ni/Cu atomic ratio of 9/1~1/4, the conversion for HYD and HDO reactions of the catalysts were 90-93% and 95-99%, respectively. The tendency to exhibit almost constant reaction activity in these catalysts of different Ni/Cu atomic ratios implies a typical structure-insensitive reaction. The refined bio-oil produced by hydrotreating (HDY and HDO) had significantly lower iodine value, acid value, and kinetic viscosity than the raw bio-oil and the higher heating value (HHV) was increased by about 10%.

• Journal of Energy Engineering
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• v.8 no.2
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• pp.256-264
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• 1999

The performance of the Pt-B/cordierite catalysts (2 wt%) Pt, 70 wt% Alumina, 28 wt%) Ceria and Zirconia, B: base metal) loaded with 6∼12 wt% Mn, Cu, V, Co, Cr and Ba, respectively was studied for partial oxidation of methane reaction and compared with that of Ni loaded catalyst. As a results, it was found that Ba, Co, Cr as well as Ni loaded catalysts showed higher activity for methane partial oxidation of methane than the Mn, Cu and V loaded catalyst. But it was known that catalysts having good activity for methane showed the good activity for coke formation, too. A XRD analysis of the catalyst before and after the reaction using 5 wt% Ni/Al$_2$O$_3$) showed that there were three Ni phases. In these results, it was found that methane oxidation reaction occulted at the front of the catalyst bed consisted of NiAl$_2$O$_4$and NiO and reforming reaction occurred at the rear part of the catalyst bed consisted of reduced Ni.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.1
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• pp.64-73
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• 2007

The catalytic activity of transition metals (Cu, Co, Mn, Fe and Ni) supported on ${\gamma}-Al_2O_3$ for the oxidation of toluene was investigated in the microreactor of fixed-bed type. The catalytic activity of transition metals for the oxidation of toluene turned out to be increasing in the order of Ni$Cu/{\gamma}-Al_2O_3$ catalysts for the oxidation of toluene increased with the increasing loadings of copper, reached the maximum activity at 5% loadings of copper, and decreased with higher loadings of copper in the catalysts. The activity of $Cu/{\gamma}-Al_2O_3$ catalysts for the oxidation of toluene decreased with the increasing calcination temperatures. This might result from the decreasing surface area of catalysts due to the sintering of copper oxide as well as ${\gamma}-Al_2O_3$ supports. The 5wt% $Cu/{\gamma}-Al_2O_3$ catalysts calcined at $400^{\circ}C$ for 4 hrs in the air showed the highest activity for the oxidation of toluene. Mutual inhibition was observed for the binary mixture of toluene and xylene. The activity of the easy-to-oxidize toluene was greatly decreased while the difficult-to-oxidize xylene was slightly decreased in the binary mixture of toluene and xylene. It might suggest that the inhibition of toluene and xylene in the binary mixture resulted from the competitive adsorption for the adsorbed oxygen on the catalytic surface.

• Clean Technology
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• v.13 no.4
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• pp.287-292
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• 2007

[ $M/Al_2O_3$ ] (M = Mn, Fe, Co, Ni, Cu) catalysts supported on commercial alumina ($Al_2O_3$) were prepared by an impregnation method, and were applied to the hydrogen production by auto-thermal reforming of ethanol. It was revealed that each catalyst retained its own metallic phase and product distribution strongly depended on the identity of active metal. Among the catalysts prepared, $Ni/Al_2O_3$ and $Co/Al_2O_3$ showed the best catalytic performance in the auto-thermal reforming of ethanol. However, the reaction mechanisms over these two catalysts were different. Ni/Al_2O_3 catalyst showed 100% ethanol conversion at $500^{\circ}C$, but it exhibited a rapid decrease in hydrogen selectivity. Although $Co/Al_2O_3$ catalyst showed an excellent performance in hydrogen selectivity, on the other hand, no significant improvement in hydrogen yield was observed due to the low ethanol conversion over the catalyst.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.451-454
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• 2006

WGS reaction over Mo2C and ceria based catalysts was investigated to develop an alternative commercial Cu-Zn/Al2O3 catalyst for fuel processor and hydrogen station. The Mo2C catalysts were prepared by a temperature programmed method and the various metal supported cerium oxide catalysts were prepared by an Impregnation method. The catalysts were characterized by the N2 physisorption, Co chemisorption, XRD, TEM and TPR. It was found that Mo2C and 0.2wt% Pt-40wt%, Ni/CeO2 catalysts had higher activity and stability than the Cu-Zn/Al203 above $260^{\circ}C$. Moreover, CO conversion of more than 85% was observed at $280{\sim}300^{\circ}C$. But all catalysts were deactivated during the thermal cycling runs. The results suggest that these catalysts are an attractive candidate for the alternative Cu-Zn/Al2O3 catalyst for fuel processor and hydrogen station applications.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.651-656
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• 2005

Toluene, which is emitted from textile process, is considered as an important hazardous air pollutant. In this study, the catalytic activity of transition metal oxides(Cu, Mn, V, Cr, Co, Ni, Ce, Sn, Fe, Sr, Cs, Mo, La, W, Zn)/${\gamma}-Al_2O_3$ catalysts was investigated to carry out the complete oxidation of toluene. The metal catalysts were characterized by XRD-ray diffraction), FE-SEM(Field Emission Scanning Electron Micrograph), BET(Brunauer Emmett Teller) method and TPR(Temperature Programmed Reduction). Among the catalysts, Cu/${\gamma}-Al_2O_3$ was highly promising catalyst for the oxidation of toluene. From the BET results, it seems that the catalytic activity is not correlated to the specific surface area. XRD results indicated that most of catalysts exist as amorphous phase. From the FE-SEM results, it was observed that copper on ${\gamma}-Al_2O_3$ surface was well dispersed among catalysts. The catalytic activity for the toluene oxidation could be explained with that metal oxide catalyst was dispersed well over supports and was attributed to reduction activity in surface of catalysts.

• Journal of the Korean Applied Science and Technology
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• v.33 no.2
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• pp.401-410
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• 2016

The $Pt-Sn/Al_2O_3$ catalysts mixed with metal oxides for propane dehydrogenation were studied. $Cu-Mn/{\gamma}-Al_2O_3$, $Ni-Mn/{\gamma}-Al_2O_3$, $Cu/{\alpha}-Al_2O_3$ was prepared and mixed with $Pt-Sn/Al_2O_3$ to measure the activity for propane dehydrogenation. As standard sample, $Pt-Sn/Al_2O_3$ catalyst mixed with glassbead was adopted. In the case of catalytic activity test after non-reductive pretreatment of catalyst and metal oxide, $Pt-Sn/Al_2O_3$ mixed with $Cu-Mn/{\gamma}-Al_2O_3$ showed higher conversion of 15% and similar selectivity at $576.5^{\circ}C$, compared to conversion of 8% in standard sample. In the case of catalytic activity test after reductive pretreatment of catalyst and metal oxde, $Cu/{\alpha}-Al_2O_3$ showed higer yield than standard sample. But, increase of yield of most of samples after reductive pretreatment was not significant, so it was found that lattice oxygen of $Cu-Mn/{\gamma}-Al_2O_3$ is effective to propane dehydrogenation.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.363-368
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• 2006

This study selected the optimal catalyst for the process of producing $C_9$-alcohol by hydrogenating $C_9$-aldehyde, and carried out an experiment in order to establish the operating condition for maximizing the yield of $C_9$-alcohol. The BET surface area and the specific area of copper were most excellent in $CuO/ZnO/Al_2O_3$ (60:30:10 wt％) catalyst produced using acetate as a precursor of copper and $Na_2CO_3$ as a precipitant, and the catalyst also showed the highest performance in $C_9$-aldehyde hydrogenation. Using a trickle bed reactor loaded with optimized catalyst, we attained 94.1 wt％ yield of $C_9$-alcohol under the condition of $175^{\circ}C$, 800 psi and $WHSV=3hr^{-1}$. According to the result of comparing with other catalysts used in the hydrogenation of aldehyde, the catalyst showed similar performance to that of Ni/kieselghur and higher than that of $Cu-Ni-Cr-Na/Al_2O_3$ and $Ni-Mo/Al_2O_3$. According to the result of examining the stability of the catalyst through a long-term catalysis test, the yield of $C_9$-alcohol decreased slowly after around 72 hours due to the increasing production of high boiling-point byproducts.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.3
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• pp.249-255
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• 1999

We sdudied effect of additives on catalytic activity in thermal catalytic de-NOx process which was composed of thermal reduction, catalytic reduction and catalytic oxidation stage. Pd-Pt/${\gamma}$-$Al_2O_3$ catalysts with the addition of transition metals(Co, Cu, Fe, Ni, W, Zn, Zr) and rare earth metals(Ce, Sr) were prepared by the conventional washcoating method. Those catalysts were characterized by CO pulse chemisorption, ICP, $N_2$ adsorption, SEM and XRD. The effect of catalyst additives on NOx removal for diesel emission was studied in thermal catalytic de-NOx process at reduction temperature(350~50$0^{\circ}C$), space velocity(5,000~20,000 $hr^{-1}$) and the engine load(0~120kW). The concentraton of CO, $CO_2$, NO and $NO_2$ in the exhaust gas increased with the engine load. On the other hand the concentration of $O_2$ decreased. The de-NOx activityof all prepared catalysts increased with respect to high CO and low $O_2$ level in the thermal reduction stage of the process. Insertion of Ce to Pt-Pd/${\gamma}$-$Al_2O_3$ catalyst showed the best activity of all the catalysts under these experimental conditions. De-NOx catalysts are effective to remove CO in addition to NOx in the catalytic reduction stage.