• Applied Chemistry for Engineering
• /
• v.1 no.2
• /
• pp.240-248
• /
• 1990

The catalytic activity and selectivity of metal loaded H-mordenite for transalkylation of $C_9$ aromatics were studied in a continuous flow fixed bed reactor under high pressure. Nickel loaded H-mordenite(T-Ni) catalyst showed high activity and slow decay of activity. Molybdenum and nickel loaded H-mordenite(T-NiMo) catalyst also showed high activity and suppressed coking of hydrocarbons. The selectivity of xylene for T-Ni and T-NiMo catalysts decreased with temperature, but that for T catalyst(commercial grade) monotonically increased with temperature within the experimental range. The performance of T-Ni and T-NiMo catalysts was better than that of T catalyst in terms of initial activity and its decay. The addition of Mo improved slightly stability of T-Ni catalyst.

• Applied Chemistry for Engineering
• /
• v.4 no.2
• /
• pp.308-317
• /
• 1993

The study is related to the synthesis of acrylic acid by selective oxidation of acrolein on Mo-V-W multicomponent mixed oxide catalysts. Mo-V-W-O(WVM), Mo-V-O/Mo-W-O(VM/WM), Mo-W-O/Mo-V-O(WM/VM) and mechanical mixtures of Mo-V-O and Mo-W-O(M-VM+WM) were prepared and characterized by BET, XRD, SEM and EPMA. Catalytic activity of these catalysts was tested in a continuous fixed bed reactor. In WVM catalysts small amount of tungsten added to VM increased surface area and selectivity of acrylic acid, but excess amount of tungsten decreased reaction rate of acrolein and selectivity. VM/WM catalysts, VM supported on WM, showed higher activity and selectivity than WM/VM catalysts where WM is supported on VM. Phase cooperation between WM and VM was observed in mechanical mixture of WM and VM and they showed higher yield than WM or VM.

• Applied Chemistry for Engineering
• /
• v.5 no.2
• /
• pp.295-304
• /
• 1994

$Mo-V-O/SnO_2$(VM/Sn) and $SnO_2/Mo-V-O$(Sn/VM) catalysts have been prepared and characterized by XRD, BET, SEM and TPD of ammonia. The catalytic reaction of acrolein oxidation with these catalysts, in a continuous-flow fixed-bed reactor, showed that they had higher conversion of acrolein and higher yield of acrylic acid than those of Mo-V-O itself. The origin of the observed synergy studied by TPD, TPR and TPO is explained by the cooperation of $SnO_2$ and Mo-V-O at their interfaces where electrons flow from Mo-V-O phase to $SnO_2$ and $SnO_2$ produces spill-over oxygens, which, by being transported onto the surface of Mo-V-O, reoxidize the partially reduced active sites.

• Applied Chemistry for Engineering
• /
• v.19 no.5
• /
• pp.512-518
• /
• 2008

The present work studied the selective catalytic reduction (SCR) of NO to $N_2$ by $NH_3$ over $V/TiO_2$ focusing on NOx control for the stationary sources. The SCR process depends mainly on the catalyst performance. The reaction characteristics of SCR with $V/TiO_2$ catalysts were closely examined at low and high temperature. In addition, adsorption and desorption characteristics of the reactants on the catalyst surface were investigated with ammonia. Seven different $TiO_2$ supports containing the same loading of vanadia were packed in a fixed bed reactor respectively. The interaction between $TiO_2$ and vanadia would form various non-stoichiometric vanadium oxides, and showed different reaction activities. There were optimum calcination temperatures for each samples, indicating different reactivity. It was finally found from the $NH_3-TPD$ test that the SCR activity was nothing to do with $NH_3$ adsorption amount.

• Clean Technology
• /
• v.5 no.2
• /
• pp.63-68
• /
• 1999

The activities of Ni(20wt%)/$La_2O_3$, Ni(20wt%)/${\gamma}-Al_2O_3$, and Ni(20wt%)/$SiO_2$ catalyst for $CO_2$ reforming of $CH_4$ were investigated in a fixed bed flow reactor under atmospheric condition. Catalyst characterization using XRD, TEM, SEM, BET analysis were also conducted. The catalytic activity of Ni(20wt%)/$La_2O_3$ catalyst has relatively superior to that of Ni(20wt%)/${\gamma}-Al_2O_3$ and Ni(20wt%)/$SiO_2$ catalyst. The good activity of Ni(20wt%)/$La_2O_3$ catalyst seems to depend on reduced $Ni^{\circ}$ phases of NiO($\rightarrow$ Ni + O), $LaNiO_3$($\rightarrow$ $Ni+La_2O_3$), Ni crystalline phases, and decoration of Ni phases by lanthanum species is also an important factor. Ni(20wt%)/${\gamma}-Al_2O_3$ and Ni(20wt%)/$SiO_2$ catalyst due to surface acidity resulted in the deposition of wisker type and encapsulate carbon on the surface of catalyst, but Ni(20wt%)/$La_2O_3$ catalyst did not show carbon on the surface of catalyst up to 8.5hr reaction.

• Clean Technology
• /
• v.13 no.4
• /
• pp.266-273
• /
• 2007

The adsorption properties of the activated carbon-based adsorbents were studied to remove COS emitted from $SO_2$ catalytic reduction process on the integrated gasification combined cycle (IGCC) system in this work. Transition metal supported catalysts and mixed metal oxide catalysts were used for the $SO_2$ catalytic reduction. The mechanism of COS produced from the $SO_2$ reduction and the COS concentration s according to the reaction temperature were investigated. In this study, an activated carbon and a modified activated carbon doped with KOH were used to remove the very low concentration of COS effectively. The adsorption rate and the breakthrough time of COS were measured by a thermo gravity analyzer (TGA, Cahn Balance) and a fixed bed flow reactor equipped with GC-pulsed flammable photometric detector (PFPD), respectively. It was confirmed that the COS breakthrough time of the activated carbon doped with KOH was longer than that of an activated carbon. In conclusion, the modified-activated carbon having a high surface area showed a high adsorption rate of COS produced from the $SO_2$ reduction.

• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.5
• /
• pp.359-366
• /
• 2013

This work is investigated for the catalytic decomposition of hydrogen iodide (HI). Platinum was used as active material by loading on $ZrO_2-SiO_2$ mixed oxide in HI decomposition reaction. To obtain high and stable conversion of hydrogen iodide in severe condition, it was required to improve catalytic activity. For this reason, a method increasing dispersion of platinum was proposed in this study. In order to get high dispersion of platinum, zirconia was incorporated in silica by sol-gel synthesis. Incorporating zirconia influence increasing platinum dispersion and BET surface area as well as decreasing deactivation of catalysts. It should be able to stably product hydrogen for a long time because of inhibitive deactivation. HI decomposition reaction was carried out under the condition of $450^{\circ}C$ and 1 atm in a fixed bed reactor. Catalysts analysis methods such as $N_2$ adsorption/desorption analysis, X-ray diffraction, X-ray fluorescence, ICP-AES and CO gas chemisorption were used to measurement of their physico-chemical properties.

• Korean Chemical Engineering Research
• /
• v.51 no.4
• /
• pp.418-425
• /
• 2013

The catalytic conversion of ethanol to aromatic compounds ETA was studied over ZSM-5 heterogeneous catalysts. The effect of reaction temperature, weight hourly space velocity (WHSV), and addition of water and methanol, which are the potential impurities of bio-ethanol, on the catalytic performance was investigated in a fixed bed reactor. Commercial ZSM-5 catalysts having different Si/$Al_2$ ratios of 23 to 280 and modified ZSM-5 catalysts by addition of metal (Zn, La, Cu, and Ga) were used for the activity and stability tests in ETA reaction. The catalysts were characterized with ammonia temperature programmed desorption ($NH_3$-TPD) and nitrogen adsorption-desorption techniques. The results of catalytic performance revealed that the optimal Si/$Al_2$ ratio of ZSM-5 is about 50~80 and the selectivity to aromatic compounds decreases in the order of Zn/La > Zn > La > Cu > Ga for the modified ZSM-5 catalysts. Among these catalysts from the ETA reaction, Zn-La/ZSM-5 showed the best catalytic performance for the ETA reaction. The selectivity to aromatic compounds was 72% initially and 56% after 30 h over the catalysts at reaction temperature of $437^{\circ}C$ and WHSV of $0.8h^{-1}$.

• Applied Chemistry for Engineering
• /
• v.20 no.4
• /
• pp.407-410
• /
• 2009

18~19 wt% $KMnO_4$/$SiO_2-Al_2O_3$ with Si/Al = 1/5 and 1/10, and 20 wt% $KMnO_4$/$Al_2O_3$ were prepared by solvent evaporation method. Catalytic activity of ethylene abatement over those samples were evaluated and compared under the conditions of GHSV $1125h^{-1}$, ethylene gas (ethylene 0.2%, air 99.8%, relative humidity 50%) at 30, 40, 60 and $120^{\circ}C$ using a fixed-bed reactor. $KMnO_4$/$SiO_2-Al_2O_3$ was showed better performance than $KMnO_4$/$Al_2O_3$ by 170~210% at 30, $40^{\circ}C$, and by 60% at 60, $150^{\circ}C$, respectively.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.4
• /
• pp.723-732
• /
• 2020

The spent RHDS (Residue HydroDeSulfurization) catalyst is deactivated mainly by deposition of various contaminants such as coke, sulfur and vanadium on the surface of catalyst. To eliminate those contaminants, the following remanufacturing process was conducted. The first, heavy oil on the surface of the spent RHDS catalyst was removed by kerosene and dehydrated. The second, the high temperature incineration was carried out to eliminate coke and sulfur components deposited on the surface of spent RHDS catalyst. The third, the excessive quantity of Vanadium deposited on the surface of catalyst was removed by leaching process as follows: ultrasonic agitation was carried out at 50℃, for 10 seconds with 0.5% and 1% oxalic acid solution. The purpose of this process is to find out regenerated RHDS catalyst can be used as SCR catalyst for NOx reduction by controlling the vanadium residual content of the regenerated RHDS catalyst through leaching process. The composition of regenerated RHDS catalyst was analyzed by XRF and the NOx reduction efficiency was also measured by continuous catalytic fixed bed reactor. As the result, regenerated catalyst, with 0.5% oxalic acid, ultrasonic agitation in 10 seconds, showed the most stable NOx reduction efficiency. Also, in comparison with commercial SCR catalyst, the NOx reduction performance of regenerated catalyst was similar to that of commercial SCR catalyst at the temperature 375℃ and higher whereas was lower than commercial SCR catalyst at the temperature range between 200~250℃. Therefore, it was confirmed that the regenerated catalyst as powder form wash coated on the surface of metal corrugated substrate can be used for commercial SCR catalyst.