• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.485-489
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• 2012

We investigated vanadium (V) loading effects on selective catalytic reduction (SCR) activity and $SO_2$ resistance using commercial SCR catalysts applied on a power plant and incinerator with different amounts of V loading. These catalysts were characterized using XRD, Raman, ICP, BET analysis and found to contain $TiO_2$ (anatase) supported $V_2O_5$ added $WO_3$ and $SiO_2$. The SCR activity of the catalysts increased by increasing either the $V_2O_5$ or the $WO_3$ loading amounts; the SCR activity of the catalysts added $WO_3$ is higher than that of $WO_3$-free catalysts. As the V loading amount in the catalyst increased, the $SO_2$ durability decreased. The $V_2O_5$ supported $TiO_2$ catalyst added $WO_3$ and $SiO_2$ inhibits the deactivation process by $SO_2$. The $SO_2$ resistance of catalysts added $SiO_2$ is higher than that of catalysts added $WO_3$.

• Carbon letters
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• v.25
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• pp.33-42
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• 2018

Activated carbon (AC) was modified by ammonium persulphate or nitric acid, respectively. AC and the modified materials were used as catalyst supports. The oxygen groups were introduced in the supports during the modifications. All the supports were characterized by $N_2$-physisorption, Raman, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analysis. Methanol synthesis catalysts were prepared through wet impregnation of copper nitrate and zinc nitrate on the supports followed by thermal decomposition. These catalysts were measured by the means of $N_2$-physisorption, X-ray diffraction, XPS, temperature programmed reduction and TEM tests. The catalytic performances of the prepared catalysts were compared with a commercial catalyst (CZA) in this work. The results showed that the methanol production rate of AC-CZ ($23mmol-CH_3OH/(g-Cu{\cdot}h)$) was higher, on Cu loading basis, than that of CZA ($9mmol-CH_3OH/(g-Cu{\cdot}h)$). We also found that the modification methods produced strong metal-support interactions leading to poor catalytic performance. AC without any modification can prompt the catalytic performance of the resulted catalyst.

• Journal of Korean Society for Atmospheric Environment
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• v.6 no.1
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• pp.31-42
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• 1990

In order to suggest an efficient catalyst systems for NOx reduction of flue gases from industrial boilers, $TiO_2$ supported $WO_3-V_2O_5, V_2O_5$ and $WS_2$ catalysts were tested for the performances of NOx reduction at high reactin temperature range (250-500$^\circ$C) using a simulated flue gas system. It was found that while the proposed $WO_3/TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalysts showed a significant high NOx reduction efficiency at about 350-400$^\circ$C, the conventional commercial catalyst of $V_2O_5/TiO_2$ showed a significant drop in NOx reduction efficiency due to the excessive $NH_3$ oxidation. From the measurement of surface acidities of those catalysts, it was found that the acidity are well correlated with the activities of NOx reduction. The reason of high activity of $WO_3$ series catalysts at high reaction temperature seems due to the low value of surface excess oxygen compared with that of $V_2O_5/TiO_2$ seems equivalent to the acid site of that catalyst.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.10-15
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• 2010

Intensive works have been carried out to develop more efficient solid catalysts for biodiesel production from various feedstocks including refined oils and waste fats. Among many catalysts, metal oxides and ion exchange resins are the most intensively studied ones. With regard to metal oxide catalysts, major research activities have focused on the identification of the active compounds and their immobilizing methods on the supports. As metal oxide catalysts have strong thermal stability, they may be used in simultaneous transesterification and esterification of waste fats. However, ion exchange resin catalysts were mainly applied in the esterification of the free fatty acids in waste fats because of their lower thermal stability. For both solid catalysts, further works are needed to make them to be used in commercial process. Especially fast deactivation of the solid catalyst would be the most challenging problem.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.303-313
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• 2007

Various commercial catalysts used in chemical related applications have been disposed as an industrial waste when the catalytic activity of catalysts is not good enough to achieve an optimum yield. In addition, the amount of disposed three way catalysts (TWC) has been continuously increased. Considering the physicochemical, environmental, and economical characteristics, the deactivated spent catalysts can be treated in several alternative ways such as regeneration, recycling, and disposal. In view of the environmental and economical matters, the spent catalyst should be regenerated and used for the various purposes, although its activity is not as good as a fresh catalyst. On the other hand, spent catalysts containing noble and metal oxides can be applicable for the catalytic oxidation of volatile organic compounds (VOCs) by applying the proper treatment method. Therefore in this review the quantity of the spent catalysts and the available regeneration methods for the spent catalysts are briefly summarized and especially the proper regeneration method for applying the catalytic oxidation of VOCs and its results are introduced.

• Carbon letters
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• v.11 no.1
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• pp.38-40
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• 2010

Carbon supported electrocatalysts are commonly used as electrode materials for polymer electrolyte membrane fuel cells(PEMFCs). These kinds of electrocatalysts provide large surface area and sufficient electrical conductivity. The support of typical PEM fuel cell catalysts has been a traditional conductive type of carbon black. However, even though the carbon particles conduct electrons, there is still significant portion of Pt that is isolated from the external circuit and the PEM, resulting in a low Pt utilization. Herein, new types of carbon materials to effectively utilize the Pt catalyst are being evaluated. Carbon nanofiber/activated carbon fiber (CNF/ACF) composite with multifunctional surfaces were prepared through catalytic growth of CNFs on ACFs. Nickel nitrate was used as a precursor of the catalyst to synthesize carbon nanofibers(CNFs). CNFs were synthesized by pyrolysising $CH_4$ using catalysts dispersed in acetone and ACF(activated carbon fiber). The as-prepared samples were characterized with transmission electron microscopy(TEM), scanning electron microscopy(SEM). In TEM image, carbon nanofibers were synthesized on the ACF to form a three-dimensional network. Pt/CNF/ACF was employed as a catalyst for PEMFC. As the ratio of prepared catalyst to commercial catalyst was changed from 0 to 50%, the performance of the mixture of 30 wt% of Pt/CNF/ACF and 70wt% of Pt/C commercial catalyst showed better perfromance than that of 100% commercial catalyst. The unique structure of CNF can supply the significant site for the stabilization of Pt particles. CNF/ACF is expected to be promising support to improve the performance in PEMFC.

• Journal of the Korean Chemical Society
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• v.46 no.1
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• pp.64-68
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• 2002

Photocatalytic treatment of aqueous cyanide was studied using both commercial and home-made $TiO_2$'s as catalysts. Among the catalysts, $TiO_2$ made from $Ti(OC_3H_7)_4$ as a precursor showed the highest activity for the degradation of cyanide exceeding a commercial catalyst of Degussa P25. The difference in activities of the catalysts was mainly related to the surface properties of the catalysts such as the ratio of acidic to basic hydroxyl groups. For the catalyst which showed the highest activity, partially reduced $TiO_2$ showed better activity than calcined one.

• Clean Technology
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• v.21 no.2
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• pp.117-123
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• 2015

This inquiry was conducted to develop DeNOx catalyst for LNT. In order to develop appropriate catalysts, four catalysts, which do not use PGM (Platinum Group Metal), were carefully selected : Al/Co/Mn, Al/Co/Ni/Mn, Al/Co/Mn/Ca, Al/Co/Ni mixed metal oxides during preliminary experiments. Also, XRD, EDS, SEM, BET and TPD tests were carried as well to evaluate both physicochemical properties of such four catalysts. As a result of the experiment, four catalysts were composed of spinel-shaped crystals and had more than enough pore volume and size to have oxidation-reduction reaction of NOx gases. Additionally, through TPD test, all four types of catalysts were proved to possibly have an oxidation-reduction acid site and NO oxidation activities similar to commercial catalysts. Based on the results above, if we have further change in the composition components and active ingredients according to the catalysts that were chosen in this investigation, then we are more welcomed to expect to have an enhanced DeNox catalyst for LNT.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.151-156
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• 2010

In this paper, we characterized bimetallic Pt-Ru/C alloy catalysts having four different compositions and compared the catalytic activities of the prepared alloys for CO oxidation. ICP-AES, EDS, XRD, TEM, and XAS were used to investigate the composition, degree of alloying, particle size, and electronic structure of the prepared Pt-Ru/C catalysts. Those results indicated the synthesis of the alloy catalysts with intended composition and uniform size. The electrochemical study of the characterized alloys showed higher catalytic activity for CO oxidation than that of the commercial Pt/C (E-TEK, Inc., 20 wt %) catalyst. Especially, it was shown that the alloy catalyst with Ru composition of 50 atomic % gave the highest catalytic activity for CO oxidation.

• Journal of Environmental Science International
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• v.15 no.3
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• pp.221-227
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• 2006

Oxidative TCE decomposition over $TiO_2$-supported single and complex metal oxide catalysts has been conducted using a continuous flow type fixed-bed reactor system. Different types of commercial $TiO_2$ were used for obtaining the supported catalysts via an incipient wetness technique. Among a variety of titanias and metal oxides used, a DT51D $TiO_2\;and\;CrO_x$ would be the respective promising support and active ingredient for the oxidative TCE decomposition. The $TiO_2-based\;CrO_x$ catalyst gave a significant dependence of the catalytic activity in TCE oxidation reaction on the metal loadings. The use of high $CrO_x$ contents for preparing $CrO_x/TiO_2$ catalysts might produce $Cr_2O_3$ crystallites on the surface of $TiO_2$, thereby decreasing catalytic performance in the oxidative decomposition at low reaction temperatures. Supported $CrO_x$-based bimetallic oxide systems offered a very useful approach to lower the $CrO_x$ amounts without any loss in their catalytic activity for the catalytic TCE oxidation and to minimize the formation of Cl-containing organic products in the course of the catalytic reaction.