Aeronautics and Astronautics Unit

Muroran, Japan

Aeronautics and Astronautics Unit

Muroran, Japan
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Kanda Y.,Applied Chemistry Research Unit | Temma C.,Muroran Institute of Technology | Sawada A.,Muroran Institute of Technology | Sugioka M.,Aeronautics and Astronautics Unit | Uemichi Y.,Applied Chemistry Research Unit
Applied Catalysis A: General | Year: 2014

Effects of reduction temperature and phosphorus loading on rhodium phosphide (Rh2P) formation and on the catalytic activity of Rh-xP catalysts for hydrodesulfurization (HDS) were investigated to prepare highly active HDS catalysts. Analysis of the Rh-xP catalysts showed that a suitable P loading for HDS activity is 1.5 wt% - four times greater than that of an Rh catalyst. Temperature-programmed reduction and X-ray diffraction analyses of the Rh-xP catalysts showed that Rh2P is readily formed in catalysts with higher P loading. In contrast, the results of transmission electron microscopy observation and CO adsorption experiments indicated that the Rh2P particle size increased with increasing P content. Thus, the high HDS activity of the Rh-1.5P catalyst was explained by the formation of small Rh2P at a relatively low reduction temperature (550°C). © 2014 Elsevier B.V. All rights reserved.


Kanda Y.,Applied Chemistry Research Unit | Nakata K.,Muroran Institute of Technology | Temma C.,Muroran Institute of Technology | Sugioka M.,Aeronautics and Astronautics Unit | Uemichi Y.,Applied Chemistry Research Unit
Journal of the Japan Petroleum Institute | Year: 2012

The effects of the support on active site formation and hydrodesulfurization (HDS) activity of Rh2P catalyst were examined, using metal oxides (MO x), such as SiO 2, TiO 2, Al 2O 3, MgO and ZrO 2, as the support. Rh2P was formed on MO x support after reduction of supported rhodium and phosphorus (Rh-P) catalysts. However, differences in the formation temperatures of Rh2P were observed by changing the MO x support. Furthermore, the HDS activities of the supported Rh-P catalysts strongly changed with higher reduction temperature. The order of HDS activities of Rh-P/MO x catalysts reduced at optimal temperatures was SiO 2 ~ TiO 2 ~ Al 2O 3 MgO ZrO 2. The TOF of Rh-P/MO x catalysts was enhanced by increasing the reduction temperature to form Rh2P. The order of TOF of supported Rh2P catalysts was TiO 2 ZrO 2 Al 2O 3 SiO 2 MgO, and this order disagreed with that of thiophene conversion. The high TOF of Rh-P/TiO 2 catalyst may be explained by formation of partially sulfided TiO 2 in the HDS reaction. The low TOF of Rh-P/MgO catalyst was attributed to the basicity of the support with low sulfur tolerance.


Kanda Y.,Applied Chemistry Research Unit | Araki T.,Muroran Institute of Technology | Sugioka M.,Aeronautics and Astronautics Unit | Uemichi Y.,Applied Chemistry Research Unit
Journal of the Japan Petroleum Institute | Year: 2013

Catalytic properties of ruthenium phosphide (Ru2P) supported on silica for hydrodenitrogenation (HDN) of pyrrole were compared with those of Ru/SiO2 catalyst to clarify the effect of phosphidation. At higher W/F (652 g h mol-1), pyrrole conversion over Ru/SiO2 catalyst remarkably decreased with increasing reduction temperature. In contrast, pyrrole conversion over P-added Ru (Ru-P/SiO2) catalyst at the same W/F was enhanced with increasing reduction temperature due to Ru 2P formation. This activity was higher than that of sulfided NiMoP/Al2O3 catalyst but lower than that of Ru/SiO 2 catalyst at the same W/F. At lower W/F (130-391 g h mol -1), Ru-P/SiO2 catalyst showed higher activity and stability for pyrrole HDN than Ru/SiO2 catalyst. The cracking products (almost all CH4) were formed over Ru/SiO2 catalysts and butanes were formed over Ru-P/SiO2 catalysts. The results of CO adsorption and TEM images revealed that the particle size of Ru-P/SiO2 catalyst was smaller than that of Ru/ SiO2 catalyst. The TOF of Ru-P/SiO2 catalyst increased with reduction temperature, and this TOF was lower than that of Ru/SiO2 catalyst. After HDN reaction, the peak of particle size distribution for Ru/SiO 2 catalyst shifted to larger diameter, whereas that of Ru-P/SiO 2 catalyst remained the same. Therefore, the stable activity of Ru-P/SiO2 catalyst can be explained by excess phosphorus species acting to stabilize Ru2P particles.


Kanda Y.,Applied Chemistry Research Unit | Ichiki T.,Muroran Institute of Technology | Kayaoka S.,Muroran Institute of Technology | Sawada A.,Muroran Institute of Technology | And 2 more authors.
Chemistry Letters | Year: 2013

The effect of precursors on the active phase formation and hydrodesulfurization activities of noble metal phosphide catalysts was examined. The maximum activities of PdP and RhP catalysts prepared from acetylacetonato (acac) complex were observed at lower reduction temperatures than those for catalysts prepared from chlorides (Cl). The PdP catalyst prepared from acac also showed higher activity than that obtained from Cl. However, this trend was not observed in the RhP catalyst. The characterization results revealed that the higher activity of the PdP catalyst prepared from the acac is due to the highly dispersed Pd4.8P. © 2013 The Chemical Society of Japan.

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