Papers by Keyword: Methanol Decomposition

Abstract: The catalytic activity of Ni-Al (Ni25Al) nanoparticles fabricated by thermal plasma evaporation was examined for methanol decomposition and CO oxidation. The nanoparticles exhibited high activity for both reactions. Characterization of the nanoparticles revealed that the fabricated nanoparticles were mainly comprised of Ni and Ni₃Al phases. During CO oxidation, the Ni phase was oxidized to NiO, while the Ni₃Al phase remained unchanged. The NiO phase is supposed to serve as the active sites for CO oxidation. In contrast, during methanol decomposition, no obvious oxidation was observed for both Ni and Ni₃Al phases. The Ni and Ni₃Al phases are supposed to contribute to the high activity for methanol decomposition.

Abstract: The effect of acid and alkali leaching on catalytic activity of an atomized Ni₃Al powder for methanol decomposition was investigated. It was found that a two-step process, an acid leaching followed by an alkali leaching, was most effective for improving the activity. The optimal conditions of acid and alkali leaching were examined. The effect of the acid and alkali leaching was attributed to the formation of fine Ni species and a porous surface structure.

Abstract: The objective of this study is to investigate the catalytic properties of intermetallic Ni₃Fe foil. We fabricated Ni₃Fe foil of 30 µm in thickness by a metallurgical process, and examined the catalytic activity of the Ni₃Fe foil for methanol decomposition from 513 to 973 K. The Ni₃Fe foil showed activity for methanol decomposition above 623 K. The activity increased with the increase of reaction temperature. Surface analysis revealed that a surface structure of fine Ni-Fe particles dispersed on carbon nanofibers was formed on the foil during the reaction. The activity is attributed to the formation of this fine structure.

Abstract: The catalytic properties of the cold-rolled foils of intermetallic compound TiNi were studied for hydrogen production from methanol in a temperature range of 513-793 K. The catalytic activity for methanol decomposition increased with a reaction temperature, especially above 673 K. The SEM and EDS analyses revealed the formation of numerous Ni-enriched particles dispersed in the layer of carbon fibers during the reaction. The catalytic activity of TiNi foils is attributed to those Ni-enriched particles.

Abstract: This paper presents the characteristic features of the catalytic properties of the cold-rolled Ni₃Al foils for methanol decomposition which were developed in our group. Methanol was effectively decomposed into H₂ and CO over the foils above 713 K. The production rates of H₂ and CO increased with an increase of time during the initial period of reaction, indicating that the Ni₃Al foils were spontaneously activated under the reaction conditions. Surface analyses revealed that fine Ni particles dispersed on carbon nanofibers formed on the foils during the reaction. The high catalytic performance of the foils can be attributed to the spontaneous formation of this nanostructure during the reaction.

Abstract: In order to pursue high catalytic performance of Ni-Al intermetallic compounds for hydrogen production, we synthesized Ni-Al intermetallic nanoparticles from Ni-Al alloy ingots by vacuum arc plasma evaporation technique for the first time. The characterization of the synthesized nanoparticles was carried out using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy. The catalytic properties of the Ni-Al nanoparticles for methanol decomposition were evaluated. It is found that the nanoparticles had a large surface area above 70 m2/g, and showed very high catalytic activity for methanol decomposition.

Abstract: Intermetallic Ni3Al–based alloys (doped with zirconium and boron) represent a group of advanced materials with potential outstanding physical and chemical properties (such as high catalytic activity and structural stability in corrosive environments) that make them a considerable candidate for many high-tech applications. In this paper, the catalytic activity of fully dense Ni3Al-based thin foils (as thin as 50 m) possessing structures with micrometer or nanometer grain sizes is discussed. The examined material, without any additional catalytic coating, was successfully produced from as-cast coarse-grained sheets by heavy cold rolling and recrystallisation with an appropriately chosen set of parameters. The examination focuses on methanol and methanol/water mixture decomposition into H2 and CO at temperatures up to 530OC in a quartz reactor. Except for these products, a small amount (below 1%) of CO2 and dimethyl ether was observed. The catalyzed reaction began effectively at about 400OC, with a methanol conversion of about 90% or higher.

Abstract: Ni3Al has attractive high temperature properties, such as high strength and good oxidation/corrosion resistance, and is possible to be used for high temperature chemical processing and manufacture. Until now, the catalytic properties of Ni3Al were rarely investigated since the leaching of aluminum from Ni3Al is difficult to obtain a porous Raney-Ni compared to NiAl3 and Ni2Al3. In the present work, the catalytic properties of Ni3Al were examined for hydrogen production reactions from methanol. It was found that alkali-leached Ni3Al showed high activity for methanol decomposition (CH3OH→ 2H2+CO). Furthermore, Ni3Al catalysts suppress the formation of methane, i.e. they show higher selectivity for the methanol decomposition reaction than Ni catalyst. These results indicate a possibility for Ni3Al used as a catalyst for hydrogen production reaction.