Effect of the reduction condition on the catalytic activity for steam reforming process using Ni doped LaAlO 3 nano-particles

Amongst the issues associated with the commercialization of biomass gasification, the presence of tars has been one of the most difficult aspects to address. Tars are an impurity generated from the gasifier and upon their condensation cause problems in downstream equipment including plugging, blockages, corrosion, and major catalyst deactivation. These problems lead to losses of efficiency as well as potential maintenance issues resulting from damaged processing units. Therefore, the removal of tars is necessary in order for the effective operation of a biomass gasification facility for the production of high-value fuel gas. The catalytic activity of montmorillonite and montmorillonite-supported nickel as tar removal catalysts will be investigated in this study. Ni-montmorillonite catalyst was prepared, characterized, and tested in a laboratory-scale reactor for its efficiency in reforming tars using naphthalene as a tar model compound. Efficacy of montmorillonite-supported nickel catalyst was tested as a function of nickel content, reaction temperature, steam-to-carbon ratio, and naphthalene loading. The results demonstrate that montmorillonite is catalytically active in removing naphthalene. Ni-montmorillonite had high activity towards naphthalene removal via steam reforming, with removal efficiencies greater than 99%. The activation energy was calculated for Ni-montmorillonite assuming first-order kinetics and was found to be 84.5 kJ/mole in accordance with the literature. Long-term activity tests were also conducted and showed that the catalyst was active with naphthalene removal efficiencies greater than 95% maintained over a 97-h test period. A little loss of activity was observed with a removal decrease from 97% to 95%. To investigate the decrease in catalytic activity, characterization of fresh and used catalyst samples was performed using thermogravimetric analysis, transmission electron microscopy, X-ray diffraction, and surface area analysis. The loss in activity was attributed to a decrease in catalyst surface area caused by nickel sintering and coke formation.

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Effects of Supports on Hydrogen Adsorption on Pt Clusters

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.139.41 ◽

2008 ◽

Vol 139 ◽

pp. 41-46 ◽

Cited By ~ 5

Author(s):

K. Okazaki-Maeda ◽

Y. Morikawa ◽

Shingo Tanaka ◽

Masanori Kohyama

Keyword(s):

Catalytic Activity ◽

First Principles ◽

Carbon Materials ◽

Hydrogen Adsorption ◽

Nano Particles ◽

High Dispersion ◽

Graphene Sheets ◽

First Principles Calculations ◽

Small Clusters ◽

Atom Absorption

Pt nano-particles are supported on carbon materials at the electrode catalysts of protonexchange menbrane fuel cells. Pt nano-particles are desirable to be strongly adsorbed on carbon materials for high dispersion, although strong Pt-C interactions may affect the catalytic activity of small clusters. Thus we have examined H-atom absorption on Pt clusters supported or unsupported on graphene sheets, using first-principles calculations. For Pt-atom/graphene systems, a H atom is more weakly adsorbed than for a free Pt atom, and the H-Pt interaction becomes weaker if the interaction between a Pt atom and graphene becomes stronger. For the Ptn-cluster/graphene systems (n=2-4), the H-Pt interactions are also substantially changed from those for free Pt clusters. In the Pt clusters on graphene, the Pt-Pt distances are substantially changed associated with the electronicstructure changes by the Pt-C interactions. These structural and electronic changes in the Pt clusters as well as the presence of graphene itself seem to cause the changes in the absorption energies and preferential sites of H-atom absorption.

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Catalytic Activity of Oxidation-Reduction Pre-Treated Ni3Al for Methane Steam Reforming

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.89-91.645 ◽

2010 ◽

Vol 89-91 ◽

pp. 645-650 ◽

Cited By ~ 2

Author(s):

Ya Xu ◽

Dong Hyun Chun ◽

Jun Hyuk Jang ◽

Masahiko Demura ◽

Dang Moon Wee ◽

...

Keyword(s):

Catalytic Activity ◽

Steam Reforming ◽

Active Surface ◽

Methane Steam Reforming ◽

Reduction Treatment ◽

Highly Active ◽

Methane Steam ◽

Oxidation Reduction ◽

Pre Treatment ◽

Oxidation In Air

The catalytic activity of oxidation-reduction pre-treated Ni3Al powder for methane steam reforming was examined. The oxidation-reduction pre-treatment consisted of two steps: oxidation in air at various temperatures from 973 to 1373 K, and then followed by reduction in H2 at 873 K. It was found that the oxidation-reduction treatments significantly reduced the onset temperature of activity, i.e., improved the activity of Ni3Al powder at low temperatures. The characterization of Ni3Al surface showed that an outer surface layer of fine NiO particles were formed on the surface of Ni3Al after oxidation. These NiO particles were reduced to metallic Ni by the subsequent reduction treatment, resulting in the high activity for methane steam reforming. These results indicate that the Ni3Al can form highly active surface structure with oxidation-reduction treatment, having excellent heat resistance.

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Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

Advances in Materials Science and Engineering ◽

10.1155/2017/5828067 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Worawat Wattanathana ◽

Suttipong Wannapaiboon ◽

Chatchai Veranitisagul ◽

Navadol Laosiripojana ◽

Nattamon Koonsaeng ◽

...

Keyword(s):

Catalytic Activity ◽

Metal Complex ◽

Steam Reforming ◽

Organic Ligand ◽

Methane Steam Reforming ◽

Microwave Assisted ◽

Methane Steam ◽

Bet Specific Surface Area ◽

Ceria Catalysts

Palladium-impregnated ceria materials were successfully prepared via an integrated procedure between a metal complex decomposition method and a microwave-assisted wetness impregnation. Firstly, ceria (CeO2) powders were synthesized by thermal decomposition of cerium(III) complexes prepared by using cerium(III) nitrate or cerium(III) chloride as a metal source to form a metal complex precursor with triethanolamine or benzoxazine dimer as an organic ligand. Palladium(II) nitrate was consequently introduced to the preformed ceria materials using wetness impregnation while applying microwave irradiation to assist dispersion of the dopant. The palladium-impregnated ceria materials were obtained by calcination under reduced atmosphere of 10% H2 in He stream at 700°C for 2 h. Characterization of the palladium-impregnated ceria materials reveals the influences of the metal complex precursors on the properties of the obtained materials. Interestingly, the palladium-impregnated ceria prepared from the cerium(III)-benzoxazine dimer complex revealed significantly higher BET specific surface area and higher content of the more active Pdδ+ (δ > 2) species than the materials prepared from cerium(III)-triethanolamine complexes. Consequently, it exhibited the most efficient catalytic activity in the methane steam reforming reaction. By optimization of the metal complex precursors, characteristics of the obtained palladium-impregnated ceria catalysts can be modified and hence influence the catalytic activity.

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