Partial Oxidation of Methane to Synthesis Gas over Oxidized Diamond Supported Catalysts—Catalytic Behavior of Nickel and Cobalt Species—

Nishimoto, Hiroaki; Ikenaga, Naoki; Nakagawa, Kiyoharu; Konishi, Toru; Suzuki, Toshimitsu

doi:10.1627/jpi.48.290

Cited by 9 publications

(1 citation statement)

References 26 publications

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“…This result indicates that the reduction to metallic Co is not perfect. Complete reduction of Co3O4 on O-Dia could be achieved at a higher temperature of above 600 , as seen in the TPR profile 30) .…”

Section: Effect Of Reaction Conditions On Fts Withmentioning

confidence: 77%

Fischer-Tropsch Synthesis over Cobalt-loaded Oxidized Diamond Catalyst—Effect of Addition of Mn on Catalyst Performance—

哲

励

孝典

et al. 2012

J. Jpn. Petrol. Inst.

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-1 ・g-cat -1 were obtained. On O-Dia Mn-co-loaded catalyst precursor CoOx could easily be reduced under moderate H2 pretreatment conditions to give well-dispersed metallic Co particles ranging from 3 to 11 nm in diameter (average size 7.1 nm). In contrast, without Mn, the particle size distribution of Co was broad, ranging from 4 to 30 nm (average 14.9 nm) at a Co loading of 5 wt%. The role of Mn is to prevent sintering of Co during H2 reduction. KeywordsFischer-Tropsch synthesis, Powdered diamond support, Oxidized diamond support, Cobalt catalyst, Manganese have proposed the use of oxygen-treated powdered diamond (450 in air; we call this oxidized diamond and further denote as O-Dia), and several reactions using metal oxide or metal-loaded O-Dia catalysts have been reported 15)～18). A characteristic feature of the O-Dia support is a weak interaction between loaded metal oxide or metal and the surface of the O-Dia support. This weakness is simply due to the small number of functional groups on the O-Dia surface and no complex oxide formation between loaded metal oxide and the O-Dia surface. A preliminary study of Co/O-Dia catalysts for FTS has been reported 19) , with the finding that the reducibility of cobalt oxide on O-Dia support is much higher than that from the same precursor salt loaded on SiO2 having moderate or high surface area. In addition, the Co particle sizes of Co on O-Dia are small, considering the smaller surface area of O-Dia. Several research papers have described the effects of the addition of Ru and/or Re 20) ～22) , or Mn and/or Re 9), 23) to Co/SiO2 catalysts on the performance of FTS. In general, the effect of an additive has been believed to improve the dispersion of Co on the support material. As described previously 19) , Co species on O-Dia are well-dispersed on the smaller surface area of the O-Dia support.The objective of the present study is to increase dispersion of Co on O-Dia. We have examined the effect of various additives on the performance of Co/O-Dia catalyst, and found that Mn co-loaded Co/O-Dia catalyst improved catalytic activity. Detailed studies on Co _ Mn/O-Dia catalyst in the FTS are described together with catalyst characterization by transmission electron microscope (TEM), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and X-ray diffracrion (XRD) techniques. Experimental 1. Catalyst PreparationCommercial powdered diamond (General Electric Co., S.A. 24 m 2 /g, less than 0.5 μm in diameter) was used. Diamond powder was oxidized at 450 for 5 h in air. For comparison, SiO2 (Fuso Chemical Co., Ltd., S . A . 12 m 2 / g ) w a s u s e d . M e t a l s a l t s w e r e Co(CH3COO)2 ・4H2O (99.0 %, Wako Pure Chemical Industries, Ltd.) and Mn(CH3COO)2 ・4H2O (99.0 %, Nacalai Tesque, Inc.). The catalysts were prepared by impregnating an aqueous solution of metal salts onto the support and letting them stand overnight. Excess water was removed by using a rotary evaporator. Metal salt-loaded catalysts were calcined at 400 for 3 h in air. Catalyst Te...

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Section: Effect Of Reaction Conditions On Fts Withmentioning

confidence: 77%