• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.328-334
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• 2007

Chemical heat pump system of 2-propanol/acetone/hydrogen is most suitable to the recovery of waste heat of power plant. various types of 5 wt% Pt-alumina catalysts were prepared for 2-propanol dehydrogenation using sol-gel method. The characteristics and the dehydrogenation reaction rate of each catalyst were investigated. Pt-alumina xerogel catalyst has excellent reaction rate and good durability in comparison with the existing alumina supported Pt catalysts. Pt-alumina aerogel catalyst had the highest reaction rate in all prepared catalysts, but sufficient aging time was necessary to maintain its reaction rate. A potential advantage of the aerogel catalyst is the fact that the high temperature heat treatment is not required. Without heat treatment or with low temperature heat treatment, the Pt-alumina aerogel catalyst has excellent reaction rate as well as durability and this gives us the economic advantage. Alumina xerogel supported Pt catalyst prepared by incipient wetness method showed good reaction rate, and had good mechanical strength. Blank alumina xerogel prepared by sol-gel method can be used for the support of metal catalysts.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.577-585
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• 2014

Nanorod and particle shape $CeO_2$ were synthesized via hydrothermal process and precipitation method, respectively, and used as supports of Pt catalyst for water gas shift (WGS) reaction. Three different durations (12, 48, and 96h) for hydrothermal process were applied for the preparation of nanorod type $CeO_2$. 1.0 wt% of Pt was loaded on the prepared supports with incipient wetness method prior to the catalytic activity tests that were carried out at a GHSV of $95,541h^{-1}$, and a temperature range of 200 to $360^{\circ}C$. Varying duration of hydrothermal process led to the difference in physical characteristics of $CeO_2$ nanorods, such as aspect ratio, BET surface area, pore diameter, and pore volume. Consequently, the catalytic activities of Pt/$CeO_2$ nanorods were affected by the physical characteristics of the supports and appeared to be in the order of Pt/$CeO_2$(12) > Pt/$CeO_2$(48) > Pt/$CeO_2$(96). The comparison of the catalytic activities and results of the analysis (XPS, XRD, SEM, BET and TPR) for the supports revealed that the activity of the catalysts depends on chemical states of the Pt and the support materials in the temperature range that is lower than $280^{\circ}C$. However, the activity is rather dependent on the physical characteristic of the supports because the increased gas velocity limits the mass transfer of reactants in micropores of the supports.

• Clean Technology
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• v.17 no.2
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• pp.166-174
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• 2011

The xAl-yCe oxide catalysts with different mol ratios of Al/(Al+Ce) were prepared by a co-precipitation method and Pt supported on xAl-yCe oxide catalysts were synthesized by an incipient wetness impregnation method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $H_2$/CO-temperature programmed reduction ($H_2$/CO-TPR) to correlate with catalytic activities in co oxidation. Among the catalysts studied here, Pt/1Al-9Ce oxide catalyst showed the highest activity in dry and wet reaction conditions and the catalytic activity showed a typical volcano-shape curve with respect to Al/(Al+Ce) mol ratio. When the presence of 5% water vapor in the feed, the temperature of $T_{50%}$ was shifted ca. $30^{\circ}C$ to lower temperature region than that in dry condition. From CO-TPR, the desorption peak of $CO_2$ on Pt/1Al-9Ce oxide catalyst showed the highest value and well correlated the catalytic performance. It indicates that the Pt/1Al-9Ce oxide catalyst has a large amount of active sites which can be adsorbed by co and easy to supplies the needed oxygen. In addition, the amount of pentacoordinated $Al^{3+}$ sites obtained through $^{27}Al$ NMR analysis is well correlated the catalytic performance.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.251-260
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• 2011

$TiO_2$- and $SiO_2$-supported $Co_3O_4$, Pt and $Co_3O_4$-Pt catalysts have been studied for CO and $C_3H_8$ oxidations at temperatures less than $250^{\circ}C$ which is a lower limit of light-off temperatures to oxidize them during emission test cycles of gasoline-fueled automotives with TWCs (three-way catalytic converters) consisting mainly of Pt, Pd and Rh. All the catalysts after appropriate activation such as calcination at $350^{\circ}C$ and reduction at $400^{\circ}C$ exhibited significant dependence on both their preparation techniques and supports upon CO oxidation at chosen temperatures. A Pt/$TiO_2$ catalyst prepared by using an ion-exchange method (IE) has much better activity for such CO oxidation because of smaller Pt nanoparticles, compared to a supported Pt obtained via an incipient wetness (IW). Supported $Co_3O_4$-only catalysts are very active for CO oxidation even at $100^{\circ}C$, but the use of $TiO_2$ as a support and the IW technique give the best performances. These effects on supports and preparation methods were indicated for $Co_3O_4$-Pt catalysts. Based on activity profiles of CO oxidation at $100^{\circ}C$ over a physical mixture of supported Pt and $Co_3O_4$ after activation under different conditions, and typical light-off temperatures of CO and unburned hydrocarbons in common TWCs as tested for $C_3H_8$ oxidation at $250^{\circ}C$ with a Pt-exchanged $SiO_2$ catalyst, this study may offer an useful approach to substitute $Co_3O_4$ for a part of platinum group metals, particularly Pt, thereby lowering the usage of the precious metals.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.433-437
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• 2013

Electrical discharge plasma created in a multi-channel porous ceramic membrane-supported catalyst was applied to the decomposition of a volatile organic compound (VOC). For the purpose of improving the oxidation capability, the ceramic membrane used as a low-pressure drop catalyst support was loaded with zinc oxide photocatalyst by the incipient wetness impregnation method. Alternating current-driven discharge plasma was created inside the porous ceramic membrane to produce reactive species such as radicals, ozone, ions and excited molecules available for the decomposition of VOC. As the voltage supplied to the reactor increased, the plasma discharge gradually propagated in the radial direction, creating an uniform plasma in the entire ceramic membrane above a certain voltage. Ethylene was used as a model VOC. The ethylene decomposition efficiency was examined with experimental variables such as the specific energy density, inlet ethylene concentration and zinc oxide loading. When compared at the identical energy density, the decomposition efficiency obtained with the zinc oxide-loaded ceramic membrane was substantially higher than that of the bare membrane case. Both nitrogen and oxygen played an important role in initiating the decomposition of ethylene. The rate of the decomposition is governed by the quantity of reactive species generated by the plasma, and a strong dependence of the decomposition efficiency on the initial concentration was observed.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.121-129
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• 2017

Pd based catalysts were prepared by impregnating palladium precursor using incipient wetness method on $TiO_2$, $Al_2O_3$, $ZrO_2$, and $SiO_2$ and were applied for the selective oxidation of $H_2$ in the presence of CO. Their physicochemical properties were studied by X-ray diffraction (XRD), $N_2$-sorption, temperature programmed desorption of CO (CO-TPD) and (CO+$H_2O$)-TPD, temperature programmed reduction of CO (CO-TPR) and XPS a. The results of CO- and (CO+$H_2O$)-TPD showed the correlation between peak temperature of TPD and catalytic activities for $H_2$ and CO conversion. The $Pd/ZrO_2$ catalyst exhibited the highest conversion of $H_2$. The addition of $H_2O$ vapor promotes the conversion of $H_2$ and CO by inducing easy desorption of CO and $H_2$ in the competitive adsorption of $H_2O$, CO and $H_2$.

• Clean Technology
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• v.18 no.2
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• pp.162-169
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• 2012

Pt-Sn/${\theta}-Al_2O_3$ catalyst for n-butane dehydrogenation reaction was prepared by incipient wetness method. To confirm the physicochemical properties of Pt-Sn/${\theta}-Al_2O_3$ catalyst, the characterization was performed using X-ray diffraction (XRD), $N_2$ sorption analysis, temperature programmed desorption of $NH_3$ ($NH_3$-TPD), temperature programmed reduction of $H_2$ ($H_2$-TPR) techniques. Also, the catalytic activities of Pt-Sn/${\theta}-Al_2O_3$ for n-butane dehydrogenation was tested as a function of pretreatment temperature, pretreatment time, reaction temperature, and the partial pressure of n-butane and hydrogen. The sum of selectivities to n-butenes consisting of 1-butene, cis-2-butene, and trans-2-butene was almost constant 95% in the range of conversion of n-butane 5-55%. The activation energy calculated from Arrhenius equation was $82.4kJ\;mol^{-1}$ and the reaction orders of n-butane and hydrogen from Power's law were 0.70 and -0.20, respectively.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.714-722
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• 2019

Catalysts were prepared by using incipient wetness impregnation method with 17 wt% Ni on a support ($SiO_2-Y_2O_3$, $Al_2O_3$, $SiO_2-ZrO_2$, $SiO_2$, $TiO_2$, MgO) and the catalytic activity in the reductive amination of ethanol with ammonia in the presence of hydrogen was compared and evaluated. The catalysts used before and after the reaction were characterized using X-ray diffraction, nitrogen adsorption, ethanol-temperature programmed desorption (EtOH-TPD), isopropanol-temperature programmed desorption (IPA-TPD), and hydrogen chemisorption etc. In the case of preparing $ZrO_2$ and $Y_2O_3$ supports, the small amount of Si dissolution from the Pyrex reactor surface provoked the formation of mixed oxides $SiO_2-ZrO_2$ and $SiO_2-Y_2O_3$. Among the catalysts used, $Ni/SiO_2-Y_2O_3$ catalyst showed the best activity, and this good activity was closely related to the highest nickel dispersion, and low desorption temperature in EtOH-TPD and IPA-TPD. The low catalytic activity on Ni/MgO catalysts showed low activity due to the formation of NiO-MgO solid-solutions. In the case of $Ni/TiO_2$, the reactivity was low due to the low nickel metal phase due to strong metal-support interaction. In the case of using a support as $SiO_2-Y_2O_3$, $Al_2O_3$, $SiO_2-ZrO_2$, and $SiO_2$, the selectivities of ethylamines and acetonitrile were not significantly different at similar ethanol conversion.

• Clean Technology
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• v.28 no.4
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• pp.269-277
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• 2022

With the recent development of the biological enzymatic reaction industry, lactic acid (LA) can be mass-produced from biomass sources. In particular, a catalytic process that converts LA into acrylic acid (AA) is receiving much attention because AA is used widely in the petrochemical industry as a monomer for superabsorbent polymers (SAP) and as an adhesive for displays. In the LA conversion process, NaY zeolites have been previously shown to be a high-activity catalyst, which improves AA selectivity and long-term stability. However, NaY zeolites suffer from fast deactivation due to severe coking. Therefore, the aim of this study is to modify the acid-base properties of the NaY zeolite to address this shortcoming. First, base promoters, Ca ions, were introduced to the NaY zeolites to tune their acidity and basicity via ion exchange (IE) and incipient wetness impregnation (IWI). The IWI method showed superior catalyst selectivity and stability compared to the IE method, maintaining a high AA yield of approximately 40% during the 16 h reaction. Based on the NH₃- and CO₂-TPD results, the calcium salts that impregnated into the NaY zeolites were proposed to exit as an oxide form mainly at the exterior surface of NaY and act as additional base sites to promote the dehydration of LA to AA. The NaY zeolites were further treated with KOH before calcium impregnation to reduce the total acidity and improve the dispersion of calcium through the mesopores formed by KOH-induced desilication. However, this KOH treatment did not lead to enhanced AA selectivity. Finally, calcium loading was increased from 1wt% to 5wt% to maximize the amount of base sites. The increased basicity improved the AA selectivity substantially to 65% at 100% conversion while maintaining high activity during a 24 h reaction. Our results suggest that controlling the basicity of the catalyst is key to obtaining high AA selectivity and high catalyst stability.