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Kai Sundmacher - One of the best experts on this subject based on the ideXlab platform.
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steam reforming of glycerol the experimental activity of la1 xcexnio3 Catalyst in comparison to the thermodynamic reaction equilibrium
Applied Catalysis B-environmental, 2009Co-Authors: Kai Sundmacher, Vladimir Galvita, Liisa Rihkostruckmann, Heike LorenzAbstract:Abstract The steam reforming of glycerol (1,2,3-propantriol) was investigated with non-substituted and partially Ce substituted La 1− x Ce x NiO 3 mixed oxides where x = 0, 0.1, 0.3 or 0.7, and the activities were compared with Pt metal Catalysts. The Catalysts were characterised by temperature-programmed reduction (TPR), X-ray powder diffraction (XRD), BET Surface Area and carbon content. The Ni was easily reduced in the La 0.3 Ce 0.7 NiO 3 structure. The experimental results were compared with the thermodynamic equilibrium concentrations, which were calculated for the system with non-stochiometric method. The La 0.3 Ce 0.7 NiO 3 Catalyst was highly active in the glycerol steam reforming with conversions approaching to the equilibrium at temperatures between 500 and 700 °C. The formation of carbonaceous deposits on the La 0.3 Ce 0.7 NiO 3 was smallest among all the investigated La 1− x Ce x NiO 3 Catalysts. Unchanged Catalyst Surface Area (BET) during operation and low carbon deposition after reaction confirm the efficient operation and high stability of the non-noble, inexpensive Catalyst of La 0.3 Ce 0.7 NiO 3 .
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A method for rough estimation of the Catalyst Surface Area in a fuel cell
Journal of Applied Electrochemistry, 2008Co-Authors: Tanja Vidaković, Mihai Christov, Kai SundmacherAbstract:A method for a rough estimation of the Catalyst Surface Area in a fuel cell is developed. It is based on the deconvolution of experimental CO oxidation data by use of a mathematical model. The kinetic parameters of the model are determined by fitting the experimental curves. The experimental data are collected at different sweep rates (2–100 mV s−1) and at different temperatures (room −60.0 °C). The model can predict the sweep rate dependence of the CO oxidation onset potential, the peak current, the peak potential and the peak broadness. The model is further used for the prediction of the baseline in the presence of CO and for calculation of the CO charge consumed up to half peak potential. It is obtained that the latter value is constant at different sweep rates and that the baseline deviates from linearity already at low sweep rates (2 mV s−1), but not very significantly (2.0% in comparison to 8.8% at 100 mV s−1, based on calculated CO charge). It is suggested that lower sweep rates should be used for experimental Surface Area determination.
Marwan Houalla - One of the best experts on this subject based on the ideXlab platform.
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Influence of W loading on the environment of Si in WO3/ZrO2-SiO2 Catalysts
Applied Catalysis A : General, 2010Co-Authors: Sebastien Lecarpentier, Jacob Gestel, Karine Thomas, Jean-pierre Gilson, Marwan HouallaAbstract:Tungstated zirconias consist typically of WOx species deposited on zirconia support. Additives like Si can be added to stabilize the Catalyst Surface Area. The aim of this work is to identify the location of the Si (Surface or bulk) as a function of W addition. Zirconia doped with 1.2 wt% Si remained purely tetragonal and exhibited a high specific Surface Area (150 m(2)/g) following calcination at 1023 K. Infrared quantification of the silanol band at 3745 cm(-1) indicated that Si is essentially present at the Surface. The Si-29 NMR chemical shift of the zirconia is characteristic of isolated silicium. This result is corroborated with infrared by the absence of the structural band ascribed to Si-C-Si vibrations. NMR and infrared results indicated that W addition brings about a progressive evolution of the Si environment towards that of silica-like species. These results can be tentatively explained by a ligand enhanced dissolution of the support on W deposition. Si leached from the Surface will then aggregate, forming small SiO2-like domains on the zirconia. (c) 2009 Elsevier B.V. All rights reserved.
Keiichi Tomishige - One of the best experts on this subject based on the ideXlab platform.
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a comparison of rh ceo2 sio2 Catalysts with steam reforming Catalysts dolomite and inert materials as bed materials in low throughput fluidized bed gasification systems
Biomass & Bioenergy, 2004Co-Authors: Mohammad Asadullah, Tomohisa Miyazawa, Kimio Kunimori, Shuntarou Koyama, Keiichi TomishigeAbstract:Abstract The gasification of cedar wood in the presence of Rh/CeO2/SiO2 has been conducted in the laboratory scale fluidized bed reactor using air as a gasifying agent at low temperatures (823– 973 K ) in order to produce high-quality fuel gas for gas turbine for power generation. The performance of the Rh/CeO2/SiO2 Catalyst has been compared with conventional Catalysts such as commercial steam reforming Catalyst G-91, dolomite and nonCatalyst systems by measurements of the cold gas efficiency, tar concentration, carbon conversion to gas and gas composition. The tar concentration was completely negligible in the Rh/CeO2/SiO2-catalyzed product gas whereas it was about 30, 113, and 139 g / m 3 in G-91, dolomite and noncatalyzed product gas, respectively. Since the carbon conversion to useful gas such as CO, H2, and CH4 are much higher on Rh/CeO2/SiO2 Catalyst than others at 873 K , the cold gas efficiency is much higher (71%) in this case than others. The hydrogen content in the product gas is much higher (>24 vol %) than the specified level (>10 vol %) for efficient combustion in the gas turbine engine. The char and coke formation is also very low on Rh/CeO2/SiO2 Catalyst than on the conventional Catalysts. Although the Catalyst Surface Area was slightly decreased after using the same Catalyst in at least 20 experiments, the deactivation problem was not severe.
Shuang Liu - One of the best experts on this subject based on the ideXlab platform.
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soot oxidation over ceo2 and ag ceo2 factors determining the Catalyst activity and stability during reaction
Journal of Catalysis, 2016Co-Authors: Shuang Liu, Wei Liu, Wenming Chen, Rui Ran, Duan WengAbstract:Abstract Three model ceria Catalysts, which are monocrystalline CeO2 nanocubes, polycrystalline CeO2 nanoparticles, and polycrystalline CeO2 spindles, were synthesized and analyzed with isothermal soot oxidation, H2-TPR, and Raman spectroscopy. The results suggest that the initial activity of the Catalyst is determined by the number of Catalyst–soot contact points rather than the Catalyst Surface Area, while the Catalyst stability is closely related to the concentration of Surface oxygen vacancies. Excessive Surface oxygen vacancies may inhibit the regeneration of highly active O2− and lead to Catalyst deactivation during reaction. After impregnation with Ag, O− can be readily regenerated and transformed to O2−, resulting in a 10-fold increase in soot oxidation activity over Ag/CeO2. Among these Catalysts, Ag supported on nanocubic CeO2 exhibits good availability of O2− and therefore high catalytic activity and stability, and is thus considered a promising Catalyst for application in gasoline particulate filters.
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Textural–structural properties and soot oxidation activity of MnOx-CeO2 mixed oxides
Catalysis Communications, 2011Co-Authors: Shuang Liu, Duan Weng, Fan LinAbstract:Abstract A series of MnOx-CeO2 mixed oxides were prepared using a sol-gel method followed by calcinations at various temperatures. The soot oxidation activities were measured in different NO concentrations under loose contact conditions. A quasi-parabolic curve is observed for the apparent dependency of activity on the Catalyst Surface Area. As the Surface Area is below 8 m2/g, the soot oxidation is limited by the availability of NO2 due to the separation and sintering of the mixed oxides. The rate-determining step turns to be NO2 reaction with soot for the high-Surface-Area Catalysts.
Toshiaki Taniike - One of the best experts on this subject based on the ideXlab platform.
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MgO/MgCl2/TiCl4 Core–Shell Catalyst for Establishing Structure–Performance Relationship in Ziegler–Natta Olefin Polymerization
Topics in Catalysis, 2014Co-Authors: Patchanee Chammingkwan, Vu Quoc Thang, Minoru Terano, Toshiaki TaniikeAbstract:Recently we successfully established the first structure-performance relationships between the Catalyst Surface Area and propylene polymerization activity using novel MgO/MgC_l2/TiCl_4 core-shell Catalysts with non-porous and non-fragmentable features. In the present paper, we have addressed the physical and chemical natures of these novel model Catalysts in comparison with typical Ziegler-Natta Catalysts, by means of comprehensive characterization and analyses. It was clarified that the MgO/MgCl_2/TiCl_4 core-shell Catalysts offer an ideal and powerful tool to address relationships between the support architectures and polymerization performance, which had been long un-clarified
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Structure–performance relationship in Ziegler–Natta olefin polymerization with novel core–shell MgO/MgCl2/TiCl4 Catalysts
Catalysis Communications, 2012Co-Authors: Toshiaki Taniike, Patchanee Chammingkwan, Minoru TeranoAbstract:The impact of support architectures on the olefin polymerization performance of heterogeneous Ziegler–Natta Catalysts has been scarcely understood due to the complexity of pore system and the fragmentation-induced structural changes during polymerization. In this communication, a series of novel core–shell MgO/MgCl2/TiCl4 Catalysts were synthesized by utilizing poreless single-crystal MgO nanoparticles as a non-fragmentable core material. Employing these Catalysts, we have successfully established a structure–performance relationship (SPR) that the propylene polymerization activity is perfectly proportional to the Catalyst Surface Area for the first time. On the other hand, polymer properties were found to be decided by active site natures independently of the Surface Area.