Browsing by Author "Karthik, Mani"

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Bifunctional mesoporous Cu-Al-MCM-41 materials for the simultaneous catalytic abatement of NO(x) and VOCs
(2009-01-01)
Karthik, Mani
;
Lin, Liang-Yi
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
This study explored the possibility of using waste organic solvent as the source of volatile organic compound (VOC) and it served as a reducing agent of selective catalytic reduction (SCR) deNO(x) process, in which the VOC itself can be catalytically oxidized on the mesoporous Cu and/or Al substituted MCM-41 catalysts. The synthesized Cu-Al-MCM-41 catalysts were extensively characterized by powder low-angle X-ray diffraction (XRD), N(2) adsorption-desorption measurements, transmission electron microscopy (TEM), UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS), (27)Al magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR), electron paramagnetic resonance spectroscopy (EPR) and inductively coupled plasma-mass spectrometer (ICP-MS) analysis. The XRD, TEM and N2 adsorption-desorption studies clearly demonstrated the presence of a well ordered long range hexagonal array with uniform mesostructures. The Cu-Al-MCM-41 materials showed a better long-term-stability than that of copper ion-exchanged H-ZSM-5 (Cu-ZSM-5) zeolite. The Cu-Al-MCM-41 material was found to be an efficient catalyst than that of Cu-MCM-41 without aluminum for the simultaneous catalytic abatement of NO(x) and VOCs, which was attributed to the presence of well dispersed and isolated Cu(2+) ions on the Cu-Al-MCM-41 catalyst as observed by UV-Vis DRS and EPR spectroscopic studies. And the presence of aluminum (Al(3+) ions) within the framework of Cu-Al-MCM-41 stabilized the isolated Cu(2+) ions thus it led to higher and stabilized activity in terms of NO(x) reduction. (C) 2008 Elsevier Inc. All rights reserved.
Bifunctional mesoporous Cu-Al-MCM-41 materials for the simultaneous catalytic abatement of NOx and VOCs
(2009-01-01)
Karthik, Mani
;
Lin, Liang-Yi
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
This study explored the possibility of using waste organic solvent as the source of volatile organic compound (VOC) and it served as a reducing agent of selective catalytic reduction (SCR) deNO(x) process, in which the VOC itself can be catalytically oxidized on the mesoporous Cu and/or Al substituted MCM-41 catalysts. The synthesized Cu-Al-MCM-41 catalysts were extensively characterized by powder low-angle X-ray diffraction (XRD), N-2 adsorption-desorption measurements, transmission electron microscopy (TEM), UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS), Al-27 magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR), electron paramagnetic resonance spectroscopy (EPR) and inductively coupled plasma-mass spectrometer (ICP-MS) analysis. The XRD, TEM and N2 adsorption-desorption studies clearly demonstrated the presence of a well ordered long range hexagonal array with uniform mesostructures. The Cu-Al-MCM-41 materials showed a better long-term-stability than that of copper ion-exchanged H-ZSM-5 (Cu-ZSM-5) zeolite. The Cu-Al-MCM-41 material was found to be an efficient catalyst than that of Cu-MCM-41 without aluminum for the simultaneous catalytic abatement of NOx and VOCs, which was attributed to the presence of well dispersed and isolated Cu2+ ions on the Cu-Al-MCM-41 catalyst as observed by UV-Vis DRS and EPR spectroscopic studies. And the presence of aluminum (Al3+ ions) within the framework of Cu-Al-MCM-41 stabilized the isolated Cu2+ ions thus it led to higher and stabilized activity in terms of NOx reduction. (C) 2008 Elsevier Inc. All rights reserved.
Development of regenerative dye impregnated mesoporous silica materials for assessing exposure to ammonia
(2012)
Chang, Yu-Chang
;
Bai, Hsunling
;
Chiang, Hsueh-Shih
;
Karthik, Mani
;
Li, Shou-Nan
The mesostructured materials MCM-41 and SBA-15 were studied as possible supports of bromocresol green (BG) dye impregnation for the ammonia gas detection because of their large surface area, high regenerative property, and high thermal stability. X-ray diffraction, transmission electron microscopy, scanning electron microscope, and N-2 adsorption analysis were used to characterize the prepared materials. These materials could sense ammonia via visible color change from yellowish-orange to blue color. The color change process of the nanostructured materials was fully reversible during 10 cyclic tests. The results indicated that the ammonia absorption responses of the two nanostructured materials were both very sensitive, and high linear correlation and high precision were achieved. As the gaseous ammonia concentrations were 50 and 5 ppmv, the response times for the SBA-15/BG were only 1 and 5 min, respectively. Moreover, the BG dye-impregnated SBA-15 was less affected by the variation in the relative humidity. It also had faster response for the detection of NH3, as well as lower manufacturing price as compared to that of the dye-impregnated MCM-41. Such feature enables SBA-15/BG to be a very promising material for the detection of ammonia gas. Implications: The detector tube is a convenient ambient ammonia detection device. However, almost all the commercial detector tubes can be used once only, which not only increases the purchase cost but also produces lots of waste. In this study, we developed two sensing materials that are sensitive for repeated usage. The two mesoporous silica-based materials, MCM-41 and SBA-15, are impregnated by an organic dye of bromocresol green to induce color change behavior that can be easily observed by the naked eye, and it is concluded that dye-impregnated SBA-15/BG is a very promising material for the detection of ammonia gas.
Modification of CaO by Organic Alumina Precursor for Enhancing Cyclic Capture of CO(2) Greenhouse Gas
(2009-06-01)
Chen, Yi-Tsen
;
Karthik, Mani
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
The modification of CaO sorbent with organic alumina precursor to enhance the sorption capacity during cyclic capture is demonstrated in this study. The results indicate that during the 10 min sorption time for each cycle, the CO(2) sorption capacity of original CaO sorbent is significantly decreased from 0.27 to 0.19 and 0.12 g CO(2)/g sorbent after 5 and 60 cycles, respectively. On the other hand, the organic alumina modified CaO has a fresh capacity of 0.22 g CO(2)/g sorbent, it increases to 0.24 g CO(2)/g sorbent after 5 cycles, and then decreases to around 0.15 g CO(2)/g sorbent after 60 cycles. When increasing the sorption time to 60 min at the 66th cycle, the sorption capacity of original CaO is 0.2, whereas it is 0.26 g CO(2)/g sorbent for organic alumina modified CaO. The results demonstrate that by adding only 5% by weight of Ca(12)Al(14)O(33) species into the CaO sorbent, the CO(2) sorption capacity can be enhanced up to similar to 27% by weight.
Modification of CaO by Organic Alumina Precursor for Enhancing Cyclic Capture of CO2 Greenhouse Gas
(2009-06-01)
Chen, Yi-Tsen
;
Karthik, Mani
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
The modification of CaO sorbent with organic alumina precursor to enhance the sorption capacity during cyclic capture is demonstrated in this study. The results indicate that during the 10 min sorption time for each cycle, the CO2 sorption capacity of original CaO sorbent is significantly decreased from 0.27 to 0.19 and 0.12 g CO2/g sorbent after 5 and 60 cycles, respectively. On the other hand, the organic alumina modified CaO has a fresh capacity of 0.22 g CO2/g sorbent, it increases to 0.24 g CO2/g sorbent after 5 cycles, and then decreases to around 0.15 g CO2/g sorbent after 60 cycles. When increasing the sorption time to 60 min at the 66th cycle, the sorption capacity of original CaO is 0.2, whereas it is 0.26 g CO2/g sorbent for organic alumina modified CaO. The results demonstrate that by adding only 5% by weight of Ca12Al14O33 species into the CaO sorbent, the CO2 sorption capacity can be enhanced up to similar to 27% by weight.
Ordered mesoporous silica particles and Si-MCM-41 for the adsorption of acetone: A comparative study
(2009-01-12)
Hung, Chinte
;
Bai, Hsunling
;
Karthik, Mani
;
環境工程研究所
;
Institute of Environmental Engineering
This study compares the surface properties and the acetone adsorption potentials of mesoporous silica particles (MSPs) and Si-MCM-41. The Si-MCM-41 and MSPs are synthesized, respectively by hydrothermal method and evaporation-induced self-assembly (EISA) method. The results show that the surface area and pore diameter of MSPs are similar to those of Si-MCM-41. But the synthesis of Si-MCM-41 frequently requires longer time and tedious procedure as compared to that of MSPs. The bulk density of MSPs is 3.0-5.0 times higher than that of Si-MCM-41. The mass-based acetone adsorption capacities of these two materials are almost similar. This implies that MSPs have a higher volume-based acetone adsorption capacity than Si-MCM-41 so that less space is required for volatile organic compounds (VOCs) adsorption using MSPs as the adsorbent. The pressure drops of both powder and pellet forms of MSPs are also smaller than those of Si-MCM-41 for adsorbing the same amount of acetone. In addition, as compared to commercial H-ZSM-5 zeolite, both MSPs and Si-MCM-41 reveal better performances on the regeneration ability. As a result, both MSPs and Si-MCM-41 show high adsorption/desorption potential but the MSPs are better as novel adsorbents in terms of overall engineering consideration. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.
Selective catalytic reduction of NO using acetone solvent vapors as the reducing agent over Cu2+ and/or Al3+ ions substituted MCM-41 catalysts
(2014-01-01)
Karthik, Mani
;
Bai, Hsunling
;
環境工程研究所
;
Institute of Environmental Engineering
Selective catalytic reduction (SCR) of nitrogen monoxide (NO) using acetone solvent vapors as the reducing agent over mesoporous Cu-MCM-41, Al-MCM-41, Cu-Al-MCM-41 and CuO supported metal oxides such as CuO/Al2O3 and CuO/SiO2 was investigated in this study. The synthesized materials were characterized by using powder low-angle X-ray diffraction (XRD), N-2 adsorption-desorption measurements, Al-27 magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR), electron paramagnetic resonance spectroscopy (EPR) and inductively coupled plasma-mass spectrometer (ICP-MS) analysis. The presence of isolated Cu2+ ions and tetrahedrally coordinated Al3+ ions within the framework of Cu-Al-MCM-41 catalyst played a vital role in this deNOx reaction as confirmed by EPR and (27)AlMAS-NMR spectroscopic studies, respectively. Among the various catalysts studied, bifunctional Cu-Al-MCM-41 was found to be the most effective catalyst for achieving maximum deNOx activity at lower temperatures of around 250-350 degrees C. Besides, Cu-Al-MCM-41 catalyst also showed higher acetone oxidation than those of Cu-MCM-41, CuO/Al2O3 and CuO/SiO2 catalysts in the entire temperature range. For higher temperature of above 400 degrees C, it was found that Cu-MCM-41 catalyst shows highest activity for the NO reduction but it shows less acetone incineration activity as compared to that of Cu-Al-MCM-41 catalyst. The study of simultaneous removal of NO and acetone solvent vapors using Cu-Al-MCM-41 and Cu-MCM-41 catalysts reveals the potential of using waste organic solvents from industry as the reducing agent of deNOx (SCR) process. (C) 2013 Elsevier B.V. All rights reserved.
Titanium Dioxide/Zeolite Catalytic Adsorbent for the Removal of NO and Acetone Vapors
(2009-10-01)
Jan, Yan-Huei
;
Lin, Liang-Yi
;
Karthik, Mani
;
Bai, Hsunling
;
環境工程研究所
This study delineates a simple and versatile approach for the removal of nitrogen monoxide (NO) and volatile organic vapors over composites of titanium dioxide (TiO(2)) catalyst/zeolite adsorbent under ultraviolet (UV) irradiation at ambient temperature. The catalytic adsorbents with different TiO(2)/H-ZSM-S zeolite ratios were prepared by a simple insipient wetness impregnation method. It was found that a 60%/40% weight ratio of TiO(2)/H-ZSM-5 composite is most effective and can achieve over 90% efficiency for the removal of NO and acetone vapors. This composite also showed a better long-term activity than that of bulk TiO(2) photocatalyst or zeolite adsorbent. The experimental results revealed that photocatalytic decomposition of NO was dramatically enhanced in the presence of acetone. NO also promoted the acetone oxidation under humid conditions. Furthermore, the co-existence of acetone and NO in the gaseous stream could reduce acid accumulation on the surface of the catalyst as confirmed by Fourier-transform infrared spectroscopy. Thus, the TiO(2)/zeolite catalytic adsorbent could have a high potential for the removal of multiple air pollutants in the indoor air environment.