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High temperature desulfurization over nano-scale high surface area ceria for application in SOFC
Navadol Laosiripojana,Rajesh Shivanahalli Kempegowda,Suttichai Assabumrungrat 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.2
In the present work, suitable absorbent material for high temperature desulfurization was investigated in order to apply internally in solid oxide fuel cells (SOFC). It was found that nano-scale high surface area CeO2 has useful desulfurization activity and enables efficient removal of H2S from feed gas between 500 to 850 oC. In this range of temperature, compared to the conventional low surface area CeO2, 80-85% of H2S was removed by nano-scale high surface area CeO2, whereas only 30-32% of H2S was removed by conventional low surface area CeO2. According to the XRD studies, the product formed after desulfurization over nano-scale high surface area CeO2 was Ce2O2S. EDS mapping also suggested the uniform distribution of sulfur on the surface of CeO2. Regeneration experiments were then conducted by temperature programmed oxidation (TPO) experiment. Ce2O2S can be recovered to CeO2 after exposure in the oxidation condition at temperature above 600 oC. It should be noted that SO2 is the product from this regeneration process. According to the SEM/EDS and XRD measurements, all Ce2O2S forming is converted to CeO2 after oxidative regeneration. As the final step, a deactivation model considering the concentration and temperature dependencies on the desulfurization activity of CeO2 was applied and the experimental results were fitted in this model for later application in the SOFC model
Isosynthesis via CO hydrogenation over SO4–ZrO2 catalysts
Watcharapong Khaodee,Nicha Tangchupong,Bunjerd Jongsomjit,Navadol Laosiripojana,Piyasan Praserthdam,Suttichai Assabumrungrat 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.3
Catalytic performances of sulfated zirconia catalysts with various contents of sulfur (from 0.1 to 0.75%)on isosynthesis were studied. It was firstly found that undoped-zirconia synthesized from zirconyl nitrate provided higher activity towards isosynthesis reaction (106 mmol kg-cat1 s1) compared to that synthesized from zirconyl chloride (84.9 mmol kg-cat1 s1). Nevertheless, the selectivity of isobutene in hydrocarbons was relatively lower. It was then observed that the catalytic reactivity and selectivity significantly improved by sulfur loading. The most suitable sulfur loading content seems to be at 0.1%,which gave the highest reaction rate and selectivity of isobutene. By applying several characterization techniques, i.e. BET, XRD, NH3- and CO2-TPD and SEM, it was revealed that the high reaction rate and selectivity towards isosynthesis reaction of sulfated zirconia catalysts are related to the acid–base properties, Zr3+ quantity and phase composition. 2010 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
Pornlada Daorattanachai,Supawadee Namuangruk,Nawin Viriya-empikul,Navadol Laosiripojana,Kajornsak Faungnawakij 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.6
The conversion of glucose, fructose, and cellulose to 5-hydroxymethylfurfural (HMF) was studied under hot compressed water. The effect of acid (H3PO4) and base (NaOH) catalysts was examined by combining experimental and theoretical studies. The experimental results showed that formation of HMF from fructose is more facile than that from glucose and cellulose. The density functional calculations explained the effect of catalysts on reaction mechanism and energy profile of glucose transformation. The ring-opening of b-glucose is predicted as the rate-limiting step in non-catalytic system, while the tautomerization or the hydride-shift is the rate-limiting step in the basic and acidic conditions, respectively.
Chatchai Veranitisagul,Nattamon Koonsaeng,Apirat Laobuthee,Navadol Laosiripojana 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.3
The ceria (CeO2) and gadolinia doped ceria (GDC; Ce1-xGdxO2-d with x = 0.10, 0.15, and 0.20) catalysts were successfully prepared via metal complex decomposition method at 900 8C for 2 h. The synthesized CeO2and GDC were found to have useful activity to convert ethane to syngas via the steam reforming reaction at the temperature range of 800–900 8C. The catalytic activity was improved with increasing Gd doping amount from 0 to 0.1 and 0.15; nevertheless, at higher Gd doping content (0.2), the improvement becomes less pronounced. Among all catalysts, Ce0.85Gd0.15O2-d showed the best steam reforming activity;furthermore, the amount of carbon formation over this catalyst was relatively low. These enhancements are mainly due to the high specific surface area and the good oxygen storage capacity (OSC) of the material. During the steam reforming process, the gas–solid reactions between the gaseous components presented in the system (C2H6, C2H4, and CH4) and the lattice oxygen (Ox) on the surface CeO2 or GDC occurs. The reactions of hydrocarbons adsorbed on the surface with Ox (CnHm + Ox! nCO + m/2(H2) + Ox-n) can prevent the formation of carbon species from hydrocarbons decomposition reaction (CnHm, nC + m/2H2). Moreover, the formation of carbon via Boudouard reaction (2CO , CO2 + C) is also reduced by the gas–solid reaction of CO with the lattice oxygen (CO + Ox, CO2 + Ox-1).
Investigation of CO2 adsorption by bagasse-based activated carbon
Anusorn Boonpoke,Amnat Chidthaisong,Siriluk Chiarakorn,Navadol Laosiripojana,Sirintornthep Towprayoon 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.1
Bagasse-based activated carbon (BAC) and amine-modified BAC were prepared and investigated for CO2adsorption capacity. Modifying BAC with amines resulted in a decrease of surface area, but the decreasing magnitude varied depending on type and loading rate of amines. At room temperature, the unmodified BAC was able to adsorb more CO2 than the amine-modified BAC. This ability was related to the higher surface area of unmodified than that of the modified BAC. When temperature increased, CO2 adsorption capacity of all absorbents was decreased. However,above 323 K and a concentration of CO2 lower than 30% v/v, the BAC modified with PEI at 5 and 25 wt% showed higher adsorption capacity. Among all adsorbents under 15% CO2 and 348 K, BAC-PEI25 showed the highest adsorption capacity (0.20 mmol/g).