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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

The oxidative dehydrogenation (ODH) of but-1-ene was carried out using the lattice oxygen in ferrite catalysts in the temperature range of 200–300 °C with a fixed-bed flow reactor at atmospheric pressure. Various ferrite catalysts, such as NiFe2O4/AC-500, ZnFe2O4/AC-500, CoFe2O4/AC-500, and CuFe2O4/AC-500, -400, -300, -280, were prepared in the presence of activated carbon in the calcination temperature range of 280–500 °C. When but-1-ene-TPR was measured using various ferrite catalysts, CuFe2O4/AC-500 progressed the ODH of but-1-ene at 200–300 °C. Among the catalysts, CuFe2O4/AC-500 showed the highest Buta-1,3-diene (BD) yield, at 270 °C. XRD and XPS analyses of the catalyst after the ODH suggested that the lattice oxygen in Cu-O bonded to the tetrahedral site (Cu2+ T) of the ferrite structure was used for the ODH. In addition, the used catalyst was recovered by re-oxidation with molecular O2. Moreover, CuFe2O4/AC-280, which calcined at 280 °C, had the highest specific surface area and improved the BD yield with an increase in contact area with but-1-ene. In the repeated ODH (reaction and regeneration cycle), CuFe2O4/AC-500 and -280 catalysts maintained BD yields of 7.5% and 11.3%, respectively. BD production is thought to be related to the amount of Cu2+ T.

DOI： 10.1016/j.apcata.2017.02.004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN PETROLEUM INST  

Isolated VOx, species incorporated in an SiO2-framework were synthesized by alkoxy-exchange reactions between Si(OEt)(4), V(Ot-Bu)(3)O, and polyethylene glycol (PEG). Similar alkoxy-exchange rates between alkoxides of vanadium and silicon with PEG were necessary to obtain isolated VOx species in the SiO2-framework. Gel was formed during the exchange reaction occurring with heating from 50 to 160 degrees C, liberating ethanol and t-butanol, and the obtained gel was calcined in air at 600 degrees C. The calcined samples were characterized by N-2 adsorption, XRD, Raman, FT-IR, H-2-TPR, and NMR techniques. Adsorption-desorption isotherms of N2 of the obtained samples exhibited H-4-type hysteresis patterns, indicating the presence of narrow neck pores. In addition, the presence of micropores was confirmed. The samples had high surface areas of approximately 1000 m(2)/g, and isolated VO43- species were present in the SiO2-framework. Oxidative dehydrogenation of ethylbenzene was performed as a test reaction, using CO2 as a mild oxidant. The reaction proceeded on the isolated VO43- species in the silica framework with high ethylbenzene conversion and high selectivity for styrene.

DOI： 10.1627/jpi.58.153

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN PETROLEUM INST  

Fischer-Tropsch synthesis (FTS) using a Co-Mn/oxidized diamond (O-Dia) catalyst was compared among a fixed bed reactor (FBR), a trickle bed reactor (TBR), and a slurry phase reactor (SPR). For TBR and SPR, hexadecane was employed as a solvent. Regardless of the reactor, the addition of 10 mol% of Mn to Co/O-Dia catalyst greatly increased CO conversion without changing selectivity to C-5 + liquid products. The highest initial CO conversion was obtained with FBR. However, with an increase in the time on stream, CO conversion decreased, due mainly to the accumulation of high molecular weight hydrocarbons (wax) on the catalyst bed. Although with TBR the initial CO conversion was 5 % lower than that with FBR, at a feed rate of the solvent from 3 to 12 mL/(g-catalyst h), CO conversion did not decrease during a prolonged run. SPR maintained the initial CO conversion for 24 h on stream, but the CO conversion was half of that with TBR. From these findings, we propose that TBR is the most appropriate reactor type for FTS.

DOI： 10.1627/jpi.57.109

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

To obtain a higher concentration of isolated VOx species, VOx species incorporated into an SiO2-frame were first synthesized by the alkoxy-exchange reaction between metal alkoxides and polyethyleneglycol. After the calcination of the synthesized samples, they were characterized by N-2 adsorption and Raman spectroscopy. The catalysts have mesopores and very high surface areas up to ca. 1000 m(2)/g, which can be controlled by the degree of polymerization of polyethyleneglycol.
Oxidative dehydrogenation of propane using lattice oxygen of VOx incorporated into an SiO2-frame was carried out with a fix-bed flow reactor at 450 degrees C under atmospheric pressure. The catalytic activity of VOx incorporated into SiO2 was compared with that of VOx loaded onto SiO2 with similar VOx loadings. VOx incorporated into SiO2 showed higher selectivity to propylene than VOx loaded onto SiO2. The higher propylene selectivity could be ascribed to isolated VO43- species in the silica framework. (C) 2012 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.cattod.2012.04.042

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Steam reforming of glycerin on Ni-loaded catalyst was performed using a ZrO2-based support material. The addition of CaO to ZrO2 improved the catalyst performance, and NiO/CaO-ZrO2 afforded glycerin conversion of 88.9% with an H-2 yield of 75.3% at 600 A degrees C. Carbon formation decreased from 4.2 to 2.0% with CaO-added catalyst. Solid solution was formed with the addition of CaO to ZrO2, and it exhibited basic characteristics. Further reduction of carbon formation during the reforming reaction was achieved by using a quaternary complex oxide catalyst NiO-CeO2/CaO-ZrO2, where glycerin conversion of 96.1% and a H-2 yield of 83.7% were achieved with carbon formation of 0.7% at 600 A degrees C.

DOI： 10.1007/s10562-011-0587-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The oxidative dehydrogenation of propane (ODHP) over NiO-Bi2O3-ZrO2 catalyst was carried out with a fixed-bed flow reactor at 400 degrees C under atmospheric pressure. NiO-Bi2O3-ZrO2 prepared by the co-precipitation method afforded moderate propane conversion of 18.6% and propylene selectivity of 56.1% at 400 degrees C. From XPS analyses of the used catalysts, NiO/ZrO2 prepared by the impregnation method exhibited reduced metallic Ni species after the ODHP for 1 h. On the other hand, NiO-ZrO2 and NiO-Bi2O3-ZrO2 prepared by the co-precipitation method exhibited predominantly NiO and Ni2O3 together with a minor amount of metallic Ni. From TPR and TPO, it was suggested that propylene was formed by the reaction with adsorbed oxygen species on NiOx, in contrast, metallic Ni promoted complete oxidation of propane to decrease propylene selectivity. Thus, to maintain Ni species in the oxidized state was crucial for the high selectivity to propylene. The additive effect of Bi2O3 is ascribed to have kept NiO in the solid solution less reducible state. In addition, once metallic Ni was formed, it could easily be oxidized to NiO or Ni2O3.

DOI： 10.1007/s10562-010-0461-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Verlag  

In order to develop the effective utilization of biomass, the gasification behavior (changes in gasification rates against conversion) of various chars prepared from biomass at 1,000°C was studied. The gasification rate of char with CO2 measured at 900°C by a thermogravimetric balance was affected by the content of indigenous mineral matter such as calcium and potassium. The gasification behavior of chars were classified into following three groups: (1) the gasification rate reached a maximum in the higher conversion region, (2) the gasification rate profile showed two peaks around char conversion of 0. 2 and 0. 6 or higher, (3) the gasification rate profile fitted the random pore model. An increase in the gasification rate in a higher char conversion region was attributed to the promotion effect of the potassium catalyst. The number of active centers in the char was obtained by the O2 uptake at 200°C using pulse technique. The number of active sites was increased by potassium and calcium in biomass and the amount of O2 uptake well correlated the char gasification rate. © 2011 Springer-Verlag.

DOI： 10.1007/s13399-011-0006-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Oxidative dehydrogenation of propane using lattice oxygen of vanadium oxide was carried out with a fix-bed flow reactor at 450 degrees C under atmospheric pressure. Vanadium oxide loaded on SiO(2) from V(t-BuO)(3)O afforded a high propylene selectivity of 88.3% with a propane conversion of 26.5% based on the lattice oxygen of vanadium oxide. The catalyst prepared with V(t-BuO)(3)O exhibited higher propane conversion and propylene selectivity than that prepared with NH(4)VO(3). Raman, XPS, and XRD analyses revealed that isolated VO(4)(3-) species seem to be active sites in the ODHP. For the dehydrogenation of propane, the lattice oxygen of the isolated VO(4)(3-) species was used to give propylene and H(2)O. The isolated VO(4)(3-) species was reduced to the isolated V(3+) species and was regenerated by oxidation with oxygen. The activity was maintained for at least 10 repeated cycles, suggesting that VO(x)/SiO(2) would be a promising catalyst for ODHP.

DOI： 10.1039/c1cy00115a

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Language：Japanese   Publisher：The Japan Petroleum Institute  

DOI： 10.11523/sekiyu.2011f.0.157.0

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Language：Japanese   Publisher：The Japan Petroleum Institute  

DOI： 10.11523/sekiyu.2011f.0.158.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN PETROLEUM INST  

The oxidative dehydrogenation of ethane (ODHE) over POn/NiO/ZrO2 (High Surface area Zirconia HSZ) catalyst was carried out with a fix-bed flow reactor at 450 degrees C under atmospheric pressure The ODHE without dilution of reactants with inert gas resulted in ethane conversion of 32 1%, with a high ethene selectivily of 64 2% and an ethene yield of 20 6% In addition, the catalytic activity did not decrease for at least 12 h In XPS analysis Ni species of NiO/HSZ catalyst after the reaction exhibited partly reduced metallic NI In contrast in POn/NiO/HSZ Ni species exhibited mostly the NiO form after the reaction It was found to be important for high ethane conversion and ethene selectivity the Ni species not to be reduced to metallic NI during the ODHE mac lion The addition of a small amount of POn to NiO/HSZ catalyst significantly contributed to the resistance to the facile reduction of NiO

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Selective oxidation of alcohols to carbonyl compounds with molecular oxygen was carried out over ruthenium supported on a CaO-ZrO2 solid solution prepared by the co-precipitation method. In the oxidation of benzyl alcohol, the Ru/CaO-ZrO2 catalyst gave benzaldehyde in a yield higher than 98% at 90 degrees C, and the turnover frequency reached 224 h(-1). The Ru/CaO-ZrO2 catalyst also exhibited high catalytic activities and selectivities to carbonyl compounds in the oxidation of aromatic ring-substituted benzylic, allylic, and aliphatic alcohols. Moreover, this catalyst exhibited high activities in the oxidation of alcohols at a low temperature (40 degrees C). The catalytic activity and oxidation state of ruthenium depended on the Ca/Zr molar ratio of the support, and the highest catalytic activity was obtained with Ca/Zr = 0.125. DRIFT and XPS analyses revealed that Run+-OH (n=3, 4) on the surface of CaO-ZrO2 were likely the active species in the oxidation of alcohols. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2010.03.018

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The mechanism for the dehydrogenation of ethylbenzene over V, Cr, and Fe oxides loaded oil activated carbon, powdered diamond, Al(2)O(3), and MgO was studied in the presence of CO(2). Vanadium oxide-loaded catalysts provided higher Styrene yields Wider CO(2) than Ar flow. The transient response method was carried out to understand the reaction behaviors of lattice oxygen of various metal oxides on the support. The results showed that lattice oxygen of vanadium oxide (V=O) was consumed in the dehydrogenation reaction and that reduced vanadium oxide was reoxidized with CO(2). A similar redox cycle was observed oil iron oxide-loaded activated carbon catalyst. Spectroscopic characterization revealed that vanadium oxide and iron oxide on the Support were reduced to a low valence state during the dehydrogenation reaction, and the CO(2) could oxidize the reduced Metal Oxides. In contrast. chromium(III) oxide Was not reduced during dehydrogenation Front these findings, the redox cycle over vanadium oxide- and iron oxide-loaded catalysts was concluded to be all important factor in promoting the catalytic activity with CO(2).

DOI： 10.1021/jp906166u

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

To produce nitrogen-free synthesis gas or hydrogen by the partial oxidation of methane using air as ail oxidant, NiO-Cr2O3-MgO complex oxide was proposed as ail effective one. Lattice oxygen of NiO in the complex oxide was effectively transferred to CH4 to give H-2 and CO in the ratio of 2-3:1 at 700 degrees C. NiO was reduced to metallic Ni during the Course of the reaction with CH4, and the reduced Ni was successfully oxidized to NiO with air at 700 degrees C. Repeated cycles of the reaction and oxidation were carried out without any loss of activity. The role of Cr2O3 seemed to weaken the Ni-O bond in NiO-MgO complex oxide, in which NiO is less reducible with CH4 at 700 degrees C. In addition, the surface oxidation state of Ni was increased to Ni3+ with Cr2O3.

DOI： 10.1021/ie9013474

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Oxidation of alcohols (benzyl alcohol, 1-phenylethanol and cinnamyl alcohol) using oxidized diamond (O-Dia)supported Pd catalyst was studied. The O-Dia supported catalyst exhibited a high catalytic activity among the support materials of Pd-loaded catalysts in the oxidation of benzyl alcohol at 85 C, showing TOFs of 850 h(-1). The addition of small amount of CeO2 to O-Dia supports further improved catalytic activity in the oxidation of 1-phenylethanol with molecular oxygen. The promotion effect of CeO2 was the suppression of acidic properties of the Pd/O-Dia, leading to dehydration and hydrogenolysis reactions of 1-phenylethanol. In addition, the Pd/CeO2/O-Dia catalyst showed a higher catalytic activity in the oxidation of various alcohols than that of Pd/O-Dia. Moreover, the basic metal oxide-promoted catalysts exhibited high catalytic activity in the dehydrogenation of 1-phenylethanol without molecular oxygen at 120 degrees C. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2009.02.039

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Language：Japanese   Publisher：The Japan Petroleum Institute  

DOI： 10.11523/sekiyu.2009f.0.58.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The gas-solid reaction between methane and the lattice oxygen of Ni, Co, and Fe-oxides loaded on various support materials produced a synthesis gas (hydrogen and carbon monoxide) at 600-800 degrees C. Metal oxides were reduced to metals or lower valence oxides, and they were re-oxidized to oxides by introducing air after the reaction. Thus, production of hydrogen or synthesis gas free from nitrogen can be achieved alternatively without using pure oxygen. As a metal oxide, Fe(2)O(3) and Rh(2)O(3)-loaded on Y(2)O(3) exhibited the highest H(2) selectivity of 60.1% with a moderate CH(4) conversion of 54% and a high lattice oxygen utilization of 84% at 800 degrees C. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cattod.2008.05.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：VSP BV  

Hydrogenation reactions of alkenes (cyclohexene, ethyl acrylate, styrene and 1,5-cyclo-octadiene) and aromatic compounds (o-, m- and p-xylene) were carried out in order to examine the activity of palladium-loaded surface-oxidized diamond (Pd/O-Dia) catalyst in liquid-phase hydrogenation. The catalytic performance was compared to commercial palladium-loaded activated carbon (Pd/C) catalyst. The catalyst activities were evaluated by conversions of reactants and H-2 uptake rates in the early stage of the reaction. In all the hydrogenation reactions of alkenes and aromatic compounds, the activity of Pd/O-Dia was almost the same as or slightly higher than that of Pd/C. Dispersion of Pd metal was measured by a CO-pulsed adsorption technique and TEM observations of the catalysts. Pd dispersions were on the same order of magnitude according to the CO-pulsed adsorption technique, although the Pd/C catalyst had a higher surface area (718 m(2)/g) than that of Pd/O-Dia (23 m(2)/g). The Pd particle sizes on O-Dia measured by TEM observation were slightly smaller than those on the activated carbon. Such highly dispersed Pd particles on O-Dia would contribute to higher activity for the hydrogenation reaction of alkenes and aromatic compounds.

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Language：Japanese   Publisher：The Japan Petroleum Institute  

DOI： 10.11523/sekiyu.2008.0.26.0

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Language：Japanese   Publisher：The Japan Petroleum Institute  

DOI： 10.11523/sekiyu.2008.0.27.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The inner wall of a narrow-bore aluminum tube was successfully oxidized to give a thin alumina wall by electrolysis. A Cu-Zn-loaded alumina-wall tube reactor afforded high performance in the steam reforming of CH3OH to supply H-2.

DOI： 10.1246/cl.2007.1342

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Language：Japanese   Publisher：The Japan Petroleum Institute  

DOI： 10.11523/sekiyu.2007f.0.187.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The oxidative dehydrogenation of ethane over NiO-loaded MgO with high surface area was carried out using a fixed-bed flow reactor at 600 degrees C under atmospheric pressure.
At 600 degrees C, the oxidative dehydrogenation of ethane (C2H6/O-2 = 1) without dilution with an inert gas resulted in C2H6 conversion of 68.8% and a high C2H4 selectivity of 52.8%, which corresponds to a C2H4 yield of 36.3%. In addition, the catalytic activity did not decrease for at least 10 h. X-ray photoelectron spectra of the catalysts after the reaction exhibited that the initial valence state of Ni2+ (NiO) was maintained during the oxidative dehydrogenation of ethane. However, when NiO-Ioaded MgO was reduced with H-2 prior to the reaction, C2H4 selectivity decreased to nearly zero and high CO and H-2 selectivities were observed with the C2H6 conversion of 50 %, indicating that partial oxidation of C2H6 proceeded. Therefore, it seems important to keep Ni species as an oxide phase on the support, and for this purpose, use of the high surface area of MgO is essential. (c) 2006 Elsevier B.V All rights reserved.

DOI： 10.1016/j.molcata.2006.06.058

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A possibility of antimony oxide as a catalyst for the selective oxidation of methane with oxygen to formaldehyde was investigated. The activity measurement was carried out at an atmospheric pressure and at 873 K, where the homogeneous gas-phase reaction was negligible. Oxidized diamond (O-Dia)-supported antimony oxide catalyst produced 1.3 mmol h(-1) g-cat(-1) of formaldehyde with a formaldehyde selectivity of 23%. On the other hand, SiO2 supported antimony oxide catalyst exhibited negligible catalytic activity. XRD and UV-vis analyses revealed that alpha-Sb2O4 was formed on the oxidized diamond while Sb6O13 was formed on SiO2. Selective oxidation of methane to formaldehyde seemed to proceed on alpha-Sb2O4 with moderate activity and selectivity to formaldehyde, via a redox cycle of alpha-Sb2O4 and Sb2O4-x. On the other hand, Sb6O13 on SiO2 was stable under the reaction conditions and the selective oxidation occurred only slightly. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2006.01.043

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Systematic and quantitative approaches for carbon nanofiber (CNF) synthesis with catalytic chemical vapor deposition (CCVD) method were performed. Ni, Co and Fe metals were impregnated from aqueous solutions of respective acetate onto spherical SiO2. The catalyst was reduced at a temperature range from 500 to 700 degrees C just before the reaction, and CH4, C2H6 or C2H4 was decomposed at 400 to 650 degrees C. On Co and Ni loaded catalyst the amount of CNF increased with an increase in the reaction temperature and showed maxima, irrespective of hydrocarbon sources. However, at a reaction temperature of 600 or 700 degrees C, on Co and Ni no CNF was obtained. Dispersion of Co metals on SiO2 was greatly affected by H-2 reduction temperature. At the higher reduction temperature, the amount of CNFs decreased on CO/SiO2 and CNF formation behavior was significantly affected by the hydrocarbon source, but on Ni/SiO2 the effects of reduction temperatures were not significant on the amounts of CNF. With all the hydrocarbon sources, the amounts of CNFs obtained at optimal conditions were as follows: Ni > Co >> Fe. TEM observation of the catalysts and CNFs grown under different conditions clarified CNF growth process, for the iron group metal loaded on SiO2. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.diamond.2005.11.025

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Language：English   Publisher：SPRINGER  

DOI： 10.1007/s10853-005-1810-5

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Language：English   Publisher：SPRINGER  

DOI： 10.1007/s10853-005-1810-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN PETROLEUM INST  

Characterization of nickel and cobalt catalysts supported on oxidized diamond (O-dia) in the partial oxidation of methane to synthesis gas was carried out by X-ray photoelectron spectroscopy (XPS) and the transient response pulse technique. Carbon deposition occurred on nickel/O-dia, but not on cobalt/O-dia catalyst at 873 K throughout prolonged reaction. XPS analyses observed partially reduced nickel oxides on nickel/O-dia catalyst after reaction with methane/oxygen (5/1) at 873 K. Co(0), partially reduced cobalt oxide, and Co(M) oxide phases were found on cobalt/O-dia catalyst after reaction at 873 K. Transient response methane/oxygen (2/1) pulse studies found a large amount of hydrogen production occurred immediately at 873 K over the nickel/O-dia catalyst. However, a very small amount of hydrogen production was seen over the cobalt/O-dia catalyst, indicating that nickel and cobalt species supported on O-dia exhibited different behavior. Transient response of the catalyst bed temperature found that endothermic reaction occurred on the nickel/O-dia catalyst at 873 K, but exothermic reaction proceeded on the cobalt/O-dia catalyst. These results suggest that methane decomposition to hydrogen is the primary reaction path over nickel/O-dia catalyst, whereas complete oxidation is the primary reaction followed by steam and carbon dioxide reforming to produce synthesis gas over the cobalt/O-dia catalyst.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ef050121q

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A new approach to synthesizing carbon nanotubes (CNTs) on the powdered diamond by catalytic chemical vapor deposition (CVD) was proposed. The catalyst was prepared by impregnating an aqueous solution of Ni(NO3)(2) or an acetone solution of Pd(CH3COO)(2) onto surface-oxidized fine powdered diamond (Ni/O-Dia, Pd/O-Dia). CNTs were obtained on the diamond by the decomposition of CH4 or C2H6 over Ni/O-Dia or Pd/O-Dia at 400-800 degrees C. CNTs on Ni/O-Dia from CH4 showed comparably straight structure to that from C2H6. CNTs on Pd/O-Dia from C2H6 at 800 degrees C exhibited uniform, thick (80-130 nm), and morphologically straight structure, which were consisted of a large numbers of thin filamentous carbons. (c) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.diamond.204.10.024

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Calcium ferrite (CaFe2O4) absorbents of hydrogen sulfide (H2S) for hot-gas cleaning were prepared in the presence of Yallourn coal (YL). Calcium and iron nitrates in aqueous solution were impregnated onto YL, which was then dried at 70degreesC in vacuo and calcined at various temperatures in air. The performance of the absorbent was evaluated using a fixed-bed flow-type reactor that was equipped with a quadrupole mass spectrometer. The surface area of the YL char-loaded CaFe2O4 (CaFe2O4/YL) was ca. 25 m(2)/g, and its value was the same order of magnitude as those of unloaded ferrites that had been prepared by a coprecipitation method. The morphological structures of CaFe2O4/YL showed a rough surface with a macroporous structure; however, the surface of unloaded ferrites prepared by the dry process and the coprecipitation method was smooth and flat. When the absorption behaviors of CaFe2O4/YL for H2S were measured at 500degreesC, the absorption capacity of H2S with CaFe2O4/YL exhibited almost 100% of the stoichiometric amount of loaded metal species and could efficiently remove 4000 ppm of H2S to a level of < 1 ppm under a space velocity of 2800 h(-1).

DOI： 10.1021/ef049907z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Oxidized diamond (O-dia) acted as an excellent support material for the partial oxidation of methane to synthesis gas. The O-dia gave the best performance among the support materials of Ni- and Co-loaded catalysts for the partial oxidation of methane at a low temperature. A nickel (3 wt.%)/O-dia catalyst afforded a high CH4 conversion of 26.5% at a CH4 to O-2 ratio of 5 to give nearly a 1 to 2 ratio of CO and H-2 with selectivities of 70% at 873 K. Cobalt (3 wt.%)/O-dia catalyst exhibited a slightly lower catalytic activity than that of Ni (3 wt.%)/O-dia catalyst, where CH4 conversion was 23.0%. No change in the support was observed in the oxidation atmosphere at a high temperature. Carbon deposition of the catalyst surface in the reaction of CH4 was examined by thermogravimetric analyses. Carbon deposition occurred on the nickel (3 wt.%)/O-dia catalyst at below 923 K, and above this temperature no carbon deposition was seen. However, on the cobalt-loaded catalyst no carbon deposition was observed at any reaction temperature. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcata.2003.12.029

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

In order to develop an efficient absorbent of H,S in coal gasification, zinc ferrite (ZnFe2O4) was prepared in the presence of carbon materials such as activated carbon (AC), activated carbon fiber (ACF), and Yallourn coal (YL). The absorption behavior of absorbents for H2S was examined using a fixed-bed flow type reactor equipped with a quadrupole mass spectrometer. Carbon material-supported ZnFe2O4 exhibited larger desulfurization capacity for H2S than unsupported ferrites. They could efficiently remove H2S from 4000 ppm levels in a simulated coal gasification gas to less than I ppm at 500 degreesC. The absorption capacity of H2S with ZnFe2O4/AC, ZnFe2O4/ACF, and ZnFe2O4/YL exhibited nearly 100% of stoichiometric amount of loaded metal species. They could be regenerated by an air oxidation in O-2-Ar (50 vol%) at 450 degreesC for 30 min. The regenerated ferrite can be used for repeated absorption of H2S with a very slight decrease in the absorption capacity. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.fuel.2003.08.019

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The possibility of CO2 as an alternative oxidant for the direct conversion of CH4 to formaldehyde was investigated. The activity of the catalyst was measured at an atmospheric pressure and temperatures at which the homogeneous gas-phase reactions were negligible. Among various metal oxides loaded on SiO2 catalysts, only vanadium oxide produced the desired product. V2O5/SiO2 and V2O5/oxidized diamond catalysts, the most effective catalysts for formaldehyde synthesis, afforded about 500 mumol h(-1) g-cat(-1) and 300 mumol h(-1) g-cat(-1) of formaldehyde at 973 K, respectively. When the reaction of CH4 was carried out in Ar atmosphere, both of the V2O5/SiO2 and V2O5/oxidized diamond catalysts lost the catalytic activity as soon as the lattice oxygen of vanadium oxide was consumed. However, the activity recovered by switching the atmosphere from Ar to CO2. These results strongly suggest that CO2 acts as an oxidant for selective oxidation of CH4 to formaldehyde via the lattice oxygen of vanadium oxide. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.molcata.2003.09.026

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We have developed a novel method of producing acetaldehyde directly from ethane using carbon dioxide. The selective oxidation of C2H6 using CO2 as an oxidant was studied over various metal oxide-loaded catalysts. Among metal oxides, vanadium oxide afforded the highest activity toward CH3CHO when it was loaded on the oxidized diamond. With a V2O5 loading level of 3 wt % on oxidized diamond, 140 mumol/h.g of catalyst of CH3CHO was obtained at 923 K with C2H6 and CO2 (1:1 mixed gas) in SV of 18 000 mL/h.g of catalyst. C2H4 and HCHO were obtained as byproducts. In the absence of CO2, no aldehydes were obtained, indicating that oxygen was supplied from CO2 through the vanadium oxide surface.

DOI： 10.1021/jp0354797

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

High yields of hydrogen and carbon nanomaterials can be obtained by the decomposition of methane using oxidized diamond-supported Ni and Pd catalysts at 873 K. This is the first report to show that oxidized diamond can serve as an active support material. The simultaneous synthesis of carbon nanomaterials and hydrogen is especially interesting. Oxidized diamond is proposed as a novel catalytic means for the synthesis of hydrogen and carbon nanomaterials, and it is suggested that oxidized diamond may catalyze unique reactions of importance in nanomaterial synthesis.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Carbon dioxide is an effective oxidant for the conversion of alkanes to chemical feedstocks. Oxidized diamond is useful as a novel catalytic support material. Oxidized diamond provided catalytic sites for the activation of alkanes under CO2 atmosphere. The present findings also suggest that the surface-properties of oxidized diamond may facilitate unique catalytic reactions, such as alkanes conversion in the presence of CO2.

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Oxidized diamond demonstrated excellent support for the dehydrogenation of light alkanes to alkenes in the presence of CO2. Oxidized diamond-supported Cr2O3 and V2O5 catalysts exhibited comparatively higher catalytic activities in the dehydrogenation of lower alkanes in the presence of CO2. In the dehydrogenation of propane, the oxidized diamond-supported Cr2O3 and V2O5 catalysts in the presence of CO2 afforded nearly twofold higher activities than that in the absence of CO2. The activity of the oxidized diamond-supported V2O5 catalyst in the dehydrogenation of propane increased with increasing reaction temperatures. Furthermore, in the dehydrogenation of n-butane and iso-butane, a promoting effect of CO2 on butane conversion and butenes yields was observed over the oxidized diannond-supported Cr2O3 and V2O5 catalysts, though the promotion effect was small.
UV-Vis analyses of the fresh and the reacted catalysts in the presence and absence of CO2 revealed that CO2 kept the surface V2O5 and Cr2O3 in a state of oxidation slightly higher than that in the absence of CO2. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0920-5861(03)00268-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

We performed partial oxidation, steam reforming, and CO2 reforming of CH4 to Synthesis gas, using oxidized-diamond-supported group VIII metal catalysts, to investigate the properties of oxidized diamond as a support material and to avoid carbon deposition on a metal-loaded catalyst. Nickel (5 wt %)/oxidized diamond afforded the highest CH4 conversion of 24% (CH4/O-2 = 5), giving CO and H-2 at 873 K for the partial oxidation of CH4. No carbon deposition was observed with a supported oxidized-diamond catalyst (5 wt % nickel loading level) in the partial oxidation of CH4 at > 923 K. In the steam reforming of CH4, ruthenium (5 wt %)/oxidized diamond afforded a CH4 conversion of 63% (CH4/H2O = 0.33), giving CO and H-2 at 873 K. Nickel, palladium, ruthenium, and rhodium (5 wt %)/oxidized diamond showed high catalytic activities for CO2 reforming of CH4 (CH4/CO2 = 1) at 873 K.

DOI： 10.1021/ef0300040

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Oxidized diamond played a significant role as an efficient support for a Cr2O3-loaded catalyst during the dehydrogenation Of C2H6 to C2H4 in the presence of carbon dioxide at 923 K, giving a 22.5% C2H4 yield with a 87.7% C2H4 selectivity. The activity of the oxidized diamond-supported Cr2O3 catalyst in the presence of CO2 was about 3 times higher than that in the absence Of CO2. The activity of the oxidized diamond-supported Cr2O3 catalyst increased with increasing CO2 Partial pressures. XPS analyses of the fresh and the reacted catalysts in the presence and absence Of CO2 revealed that CO2 maintained the surface Cr2O3 at a higher-oxidation state than the reaction in the absence Of CO2. On the other hand, bulk of Cr2O3 was not reduced in either atmosphere.

DOI： 10.1021/jp022173b

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN PETROLEUM INST  

In order to discuss the possibility of steam reforming of kerosene to produce hydrogen for the on-site fuel cell co-generation system, steam reforming of dodecane, as a model compound of kerosene, was carried out in the presence or absence of oxygen at 773-1073 K using a fixed bed flow reactor. The catalytic performance of Ru, Rh, and Ir-loaded catalysts was compared.
In the steam reforming of dodecane, Rh/La2O3 and Ru/La2O3 afforded higher dodecane conversions and hydrogen yields than those with Ir/La2O3. Dodecane conversion, however, increased with the addition of a small amount of oxygen together with steam over Ir/La2O3 catalyst, and the conversion of dodecane reached those obtained over Rh and Ru/La2O3 catalysts. Basic support La2O3 exhibited the best performance for the steam reforming in the presence of oxygen using Ir catalyst among the supports tested.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The liquefaction of low-density polyethylene was studied in several solvents with or without sulfur as an additive. With the addition of molecular sulfur in the liquefaction of polyethylene in 1-methylnaphthalene, the conversion increased from 77.8% to 100%, and the oil yield increased from 62.4% to 78.7% at 673 K, as compared to the conversion and yield results of the run in the absence of sulfur. The molecular weight distributions of the oil fraction, obtained in the presence of sulfur, shifted to the lower molecular weight side as compared to that obtained without sulfur. At an elevated temperature, molecular sulfur would generate sulfur radical, which abstracts hydrogen from polyethylene to initiate the chain reactions involved in the degradation of polyethylene. The promoting effect of sulfur on the degradation of polyethylene was affected by the chemical structure of the solvent. The promoting effect of sulfur was significant in aromatic and non-hydrogen donating compounds such as 1-metliylnaphtlialene, naphthalene, and toluene. However, in tetralin no promoting effect of sulfur was observed because the sulfur radical would abstract hydrogen from the solvent and polyethylene competitively.

DOI： 10.1021/ef020081f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

An efficient absorbent of hydrogen sulfide for hot gas cleaning was developed. In order to increase the efficiency of the absorbent, activated carbon-supported ferrite was prepared and the absorption behavior of the absorbent was examined using a fixed-bed reactor and a thermogravimetric balance.
Activated carbon-supported ferrites could be prepared at a much lower calcination temperature (400degreesC) than the typical preparation temperature of ca. 1000degreesC for a dry process, These ferrites have high surface areas up to 663 m(2)/g. Breakthrough behavior was obtained with a fixed-bed flow reactor, with almost complete absorption of hydrogen sulfide from 5000 ppm to nearly zero level being achieved at an absorption temperature of 400degreesC. The results obtained with a thermogravimetric balance indicated that the initial hydrogen sulfide absorption rate of the activated carbon-supported ferrite was about ten times higher than that of the ferrite prepared by the dry process. (C) 2002 Elsevier Science Ltd. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

The dehydrogenation of ethylbenzene over a vanadium oxide-loaded MgO catalyst was investigated using carbon dioxide. The styrene yield in the presence of carbon dioxide was 2.5 times higher than that in the absence of carbon dioxide (argon atmosphere) at 823 K, indicating that carbon dioxide markedly promoted the dehydrogenation of ethylbenzene. At 873 K, the same catalyst afforded the highest styrene yield, 73.8% with a selectivity of 90.1%, in the presence of carbon dioxide. In order to elucidate the role of carbon dioxide in this reaction, characterization of the catalyst was carried out via methods such as temperature-programmed reduction, temperature-programmed reaction with carbon dioxide, and UV-visible, FT-IR, and XRD spectroscopies. Carbon dioxide behaved as an oxidant for the vanadium species, and the surface vanadium species were kept in a high oxidation state with carbon dioxide during the dehydrogenation reaction. Active phases of vanadium in the dehydrogenation reaction were believed to be V5+ species in V2O5 or Mg3V2O8 on highly dispersed MgO. The reduced species, V4+ and V3+, were less reactive sites for the dehydrogenation. (C) 2002 Elsevier Science (USA).

DOI： 10.1006/jcat.2002.3593

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC/PLENUM PUBL  

Oxidized diamond-supported Ni catalysts gave the best performance among the oxidized diamond-supported various metal catalysts for the decomposition of methanol to synthesis gas. Ni (5 wt%)/oxidized diamond afforded 82.5% conversion of methanol to give a CO to H-2 ratio of 1.7 at 573 K.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC  

The role of CO2 in the dehydrogenation of ethane over Ga2O3-loaded catalysts was examined. Ga2O3/TiO2 catalyst was found to be the most effective for the dehydrogenation of ethane to ethene in the presence of CO2 at 923 K. The activity of the Ga2O3/TiO2 catalyst in the presence Of CO2 increased with increases in the partial pressure of CO2. To maintain high catalytic activity, cofeeding of CO2 and steam was effective in the case of the Ga2O3/TiO2 catalyst. Over the Ga2O3/TiO2 catalyst, the presence of CO2 markedly promoted the dehydrogenation of ethane as compared with the absence of CO2. Using a pulsed reaction technique, the use of CO2 in the dehydrogenation of ethane was found to reduce carbon deposition over the catalyst and to assist in the rapid desorption of the product (ethene) from the catalyst's surface. (C) 2001 Academic Press.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Oxidized diamond gave the best performance among the support materials of Ni loaded catalysts for the partial oxidation of methane. Ni(5 wt%)/oxidized diamond afforded 20% conversion of methane (CH4/O-2 = 5) to give CO and H-2 ratio of 2.0 at 873 K. Ni(5 wt%)/oxidized diamond also showed high catalytic activity for the CO2 reforming of methane.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

To prevent the plugging of a catalyst bed in a fixed bed-catalyzed coal liquefaction process. ruthenium loaded on an alumina plate catalyst is proposed. Coal slurry could pass through wide channels between plate type catalysts without leaving residue or ash. The alumina plate was prepared by anodic oxidation of an aluminum plate, and then the ruthenium was loaded onto the alumina plate from aqueous ruthenium (III) chloride solution. In the liquefaction of Tanito Harum coal with only the alumina plate in the absence of ruthenium, coal conversion of 49.4 wt% and oil yield of 29.7 wt% were obtained. The coal conversion and oil yield increased with the loading of ruthenium onto the alumina plate, and they reached maxima (conversion: 86.5 wt%, oil yield: 40.3 wt%) when 0.6 mmol of ruthenium was loaded. The ruthenium loaded on an alumina plate exhibited higher activity for coal liquefaction than ruthenium (Ru = 0.6 mmol, 5 wt%) loaded on alumina powder (conversion: 69.7 wt%, oil yield: 36.9 wt%). (C) 2001 Elsevier Science Ltd. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Co-liquefaction of micro algae (Chlorella, Spirulina, and Littorale) with coal (Australian Yallourn brown coal and Illinois No. 6 coal) was carried out under pressurized Hz in l-methylnaphthalene at 350-400 degreesC for 60 min with various catalysts. Co-liquefaction of Chlorella with Yallourn coal was successfully achieved with excess sulfur to iron (S/Fe = 4), where sufficient amount of Fe1-xS, which is believed to be the active species in the coal liquefaction, was produced. The conversion and the yield of the hexane-soluble fraction were close to the values calculated from the additivity of the product yields of the respective home-reactions. In the reaction with a one-to-one mixture of Chlorella and Yallourn coal, 99.8% of conversion and 65.5% of hexane-soluble fraction were obtained at 400 degreesC with Fe(CO)(5) at S/Fe = 4. When Littorale and Spirulina were used as micro algae, a similar tendency was observed with the iron catalyst. On the other hand, in the coliquefaction with Illinois No. 6 coal, which is known to contain a large amount of sulfur in the form of catalytically active pyrite, the oil yield in the co-liquefaction was close to the additivity of the respective reaction with Fe(CO)(5)-S, even at S/Fe = 2. Ru-3(CO)(12) was also effective for the. co-liquefaction of micro algae with coal.

DOI： 10.1021/ef000129u

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Mechanisms of partial oxidation of methane to synthesis gas were studied using a pulsed reaction technique and temperature jump measurement. Catalyst bed temperatures were directly measured by introducing 1 and 3 ml pulses of a mixture of CH4 and O-2 (2/1). With Ir, Pt and Ni/TiO2 catalysts, a sudden temperature increase at the front edge of the catalyst bed was observed upon introduction of the pulse. The synthesis gas production basically proceeded via two-step paths consisting of highly exothermic complete methane oxidation to give H2O and CO2 followed by the endothermic reforming of methane with H2O and CO2. In contrast, with the Rh and Pd/TiO2 catalysts, the temperature at the front edge of the catalyst bed decreased upon introduction of the CH4/O-2 (2/1) pulse and a small increase in the temperature at the rear end was observed, Initially, the endothermic decomposition of CH4 to H-2 and deposited carbon or CHx probably took place at the front edge of the catalyst bed, after which the deposited carbon or generated CHx species would be oxidized into COx. When the Ru/TiO2 catalyst was used, a temperature increase at the front edge of the catalyst bed was observed upon introduction of the 3 mi pulse of CH4/O-2, In contrast, the temperature drop at the front edge of the catalyst bed was observed for a 1 ml pulse of CH4/O-2. These results seemed to exhibit two possibilities for a synthesis gas formation route over the Ru/TiO2 catalyst, The reaction pathway of the partial oxidation of methane with group VIII metal-loaded catalysts depended strongly upon the metal species and reaction conditions. (C) 2001 Elsevier Science B.V. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC/PLENUM PUBL  

Alkylation of benzene with ethane was carried out using various zeolite catalysts at temperature ranges of 400-550 degreesC. Loading of platinum onto zeolite greatly enhanced the yield of ethylbenzene. Among the zeolites tested, H-ZSM5 and H-MCM22 showed catalytic activities. By contrast, mordenite did not yield ethylbenzene. Moderate acid strength distribution is the key factor of zeolite catalysts. Optimum catalyst and conditions for this reaction are as follows. The platinum-loaded H-ZSM5 catalyst containing 6.8 wt% Pt, at a reaction temperature of 500 degreesC, afforded ethylbenzene and styrene formation rates of 14.2 and 0.8 mmol h(-1) g-cat(-1), respectively (benzene-based yields 7.3 and 0.4%). In the alkylation of benzene with ethane over platinum-loaded H-ZSM5. ethene was initially formed from ethane over the metallic platinum. Then the alkylation proceeded over the acid sites of H-ZSM5.

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The reactivity of carbon species formed from methane decomposition over supported noble metal catalysts was examined. In the Ru-loaded case, the rate of formation of CHx species in the decomposition of CH4 and the amount of CHx species over Ru are independent of the type of support. However, the carbon species on Ru/La2O3 seems to be more uniform and reactive than that on Ru/Al2O3. After the decomposition of CH4 over Ru-loaded catalysts was carried out at 700 degrees C, a temperature-programmed reaction with D-2 was carried out. CD4 was the major product on all the supports, and only slight amounts of CH3D, CH2D2, and CHD3 were detected over La2O3, ZrO2, and Y2O3 supports. The reactivity of CHx species on Ru strongly depends on the supports. The reactivity of CHx species on Ru and Rh loaded on La2O3 can be divided into two categories, These categories are not based on the differences in the number of x in CHx species. On Ru, x in the CHx species is equal to nearly 0, with a very small portion having x = 2. On the other hand, x is almost exclusively 0 on Rh. It seems that Rh leads to a higher rate of decomposition for methane than does Ru. (C) 2000 Academic Press.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The coliquefaction of Yallourn coal (YL) with polyethylene (PE) was carried out at 400 or 425 degrees C under pressurized H-2 in 1-methylnaphthalene or tetralin. In the coliquefaction without a catalyst, the conversion and the oil yield increased by 11-12% as compared to that of expected value from the additive values of respective runs. We considered that free radicals produced from YL coal were stabilized by the hydrogen abstraction from PE during the coliquefaction, and as a result beta-scission of PE markedly proceeded. The addition of a large amount of Fe(CO)(5)-S catalyst (Fe = 1.0 mmol, 2.79 wt %, S/Fe = 2) increased the conversion and the hexane soluble oil yield in the homoliquefaction of YL coal or PE, except for the conversion of PE in the reaction with TL. However, this catalyst did not promote the conversion and the hexane-soluble oil yield in the coliquefaction of YL coal with PE. When the amount of the iron catalyst was decreased to 0.4 mmol (1.12 wt %) against the same amount of coal and PE, the conversion and the oil yield in the coliquefaction run increased as compared to the reaction without or with the large amount of catalyst (Fe = 1.0 mmol). Since the excess amount of the catalyst rapidly provided hydrogen from the gas phase to YL coal-derived free radicals, hydrogen transfer from PE to YL coal decreased greatly.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Dehydrogenation of ethylbenzene to styrene under excess carbon dioxide flow was carried out over activated carbon-supported metal oxide catalysts (Cr, Mn, Co, Ni, Mo, Ru, La, and Ce) at 823 K and W/F = 35 g of catalyst.h/mol. The highest yield of styrene (about 40%) with selectivity of above 80% was obtained using activated carbon-support-ed chromium oxide (Cr/AC) and cerium oxide (Ce/AC) catalysts. The initial activities of the Cr/AC and Ce/AC catalysts were comparable to that of an iron-loaded activated carbon catalyst reported previously. Only chromium(III) oxide and cerium(IV) oxide were detected by X-ray diffraction before and after reactions at higher loading levels, and these species might have been active forms. However, a reduced chromium oxide species was detected by X-ray photoelectron spectroscopy after reaction under argon. In addition to the produced styrene, equivalent amounts of carbon monoxide and water were formed. These results suggest that the dehydrogenation of ethylbenzene to styrene proceeds via two reaction paths. One is the simple dehydrogenation and an oxidation reaction of hydrogen formed with carbon dioxide. The other is the oxidative dehydrogenation of ethylbenzene through the redox cycle of chromium(III) oxide.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Carbon dioxide could oxidize the reduced vanadium oxide species on MgO and keep vanadium species at a high oxidation state, during the dehydrogenation of ethylbenzene to styrene under carbon dioxide, giving a markedly high yield and selectivity of styrene.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Dehydrogenation of ethylbenzene over supported vanadium catalysts was carried out at 723-923 K, W/F of 35-105 g-cat h/mol in a carbon dioxide atmosphere (carbon dioxide/ethylbenzene of 50-70 mmol/mmol) and in an argon atmosphere. The catalyst, 1.0 mmol of vanadium loaded on 1 g of activated carbon, afforded the highest ethylbenzene conversion of 67.1%, a styrene yield of 54.2% and a styrene selectivity of 80.8% at 550 K with a W/F of 70 g-cat h/mol of ethylbenzene in carbon dioxide. Ethylbenzene conversion and styrene yield in the presence of carbon dioxide were 14.0% higher than those in argon. During the course of the reaction, carbon dioxide was reduced to the corresponding amount of carbon monoxide against the styrene yield. As a result, the same amount of water was produced. (C) 2000 Elsevier Science B.V. All rights reserved.

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In order to understand the transformation mechanisms of iron-sulfur catalyst systems to pyrrhotite, the iron catalysts (gamma-FeOOH, alpha-FeOOH, Fe(CO)(5) and Fe-3(CO)(12)) and sulfur compounds (S and H2S) were heat-treated at 150-420 degrees C with or without an activated carbon, and then subjected to XRD and XPS analyses. Pyrrhotite (Fe1-xS) was the major phase above 200 degrees C in the XRD profiles of all iron-sulfur catalyst systems. However, the formation of pyrite (FeS2) from gamma-FeOOH and gamma-FeOOH on the catalyst surface was observed at 150-325 degrees C by XPS analyses. This result seems to indicate that active species (Fe1-xS) would be transformed through FeS2 as an intermediate, but iron carbonyl complexes were directly transformed into pyrrhotite without the formation of FeS2. (C) 2000 Elsevier Science Ltd. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BALTZER SCI PUBL BV  

Dehydrogenation of isopropylbenzene to alpha-methylstyrene was carried out using various supported metal oxide catalysts in the presence of carbon dioxide. An activated carbon-supported vanadium oxide catalyst afforded a high activity in carbon dioxide atmosphere: the alpha-methylstyrene yield in carbon dioxide atmosphere was two times greater than that in an argon atmosphere at 723 K. In order to investigate the role of carbon dioxide in this reaction, we carried out temperature-programmed reduction (TPR) studies using both fresh and used catalysts. The TPR profiles clearly indicate that carbon dioxide could keep the surface of vanadium oxide at a high oxidation state.

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Ga2O3 and Ga2O3/TiO2 catalysts were found to be effective agents for the dehydrogenation of ethane to ethene in the presence of carbon dioxide at 650 C-degrees. The activity of the Ga2O3 and Ga2O3/TiO2 catalysts in the presence of CO2 was 2-4 times higher than that without CO2. Ethene yields reached ca. 20-25% and selectivity was ca. 70-90% at 650 C-degrees in the 17% ethane and 83% CO2 feed at an SV of 9,000 ml/(g-cat h). The presence of CO2 markedly promoted dehydrogenation of ethane over Ga2O3 and Ga2O3/TiO2 catalysts. Furthermore, the promoting effect of CO2 on the aromatization of ethane and ethene over a Ga2O3+H/ZSM-5 catalyst was also observed above 650 C-degrees. Aromatics yields were higher than those without CO2.

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Mechanisms of partial oxidation of methane were studied using a pulsed reaction technique and temperature jump measurement. Catalyst bed temperatures were directly measured by introducing a pulse of a mixture of methane and oxygen (2/1), With Ir/TiO2 catalyst, a sudden temperature increase at the front edge of the catalyst bed was observed upon introduction of the pulse, but the temperature of the rear end of the catalyst bed increased only slightly. The synthesis gas production basically proceeded via a two-step path consisting of highly exothermic methane complete oxidation to give H2O and CO2, followed by the endothermic reforming of methane with H2O and CO2 over Ir/TiO2 catalyst. However, with Rh/TiO2 and Rh/Al2O3 catalysts, the temperature at the front edge of the catalyst bed decreased upon introduction of the CH4/O-2 (2/1) pulse, and a small increase in the temperature at the rear end was observed. At first, endothermic decomposition of CH4 to H-2 and deposited carbon or CHx probably took place at the front edge of the catalyst bed and then deposited carbon or generated CHx species would be oxidized into COx. However, on Rh/SiO2, synthesis gas was produced via a two-step path similar to the case of Ir/TiO2 catalyst. The reaction pathway of partial oxidation of methane with Rh-loaded catalysts depended strongly on the support materials. (C) 1999 Academic Press.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

A pulsed reaction technique was applied to discuss the effect of support on the activities and mechanisms in the CO2 reforming of methane over Ru catalyst. The reaction was carried out using a fixed bed reactor equipped with an on-line mass spectrometer. Four supports: La2O3, Y2O3 and ZrO2 which showed high activity and Al2O3, commonly used one in the reforming reaction, were compared when loaded with Ru.
After feeding CO2 at 600 degrees C, we introduced a pulse of CH4 over Ru/La2O3 catalyst under Ar steady flow. We observed the response of CO which was generated from the reaction with CHx on the ruthenium and the Ru-O-x formed during CO2 treatment or during the reaction of Ru-CHx with adsorbed CO2 onto the La2O3. Over Ru/Al2O3 catalyst, however, very small response of CO was observed. A pulse of (CO2)-C-13 was introduced under CH4 steady flow over Ru/La2O3, Ru/Y2O3 and Ru/ZrO2 catalysts. Symmetrical (CO)-C-13 responses were observed, but a small response of (CO)-C-12 from (CHx)-C-12 continued to evolve after generation of (CO)-C-13 from (CO2)-C-13 ceased.
The following reaction cycle is believed to occur in the CO2 reforming of methane on active supports: A part of metallic ruthenium reacted with CH4 to give Ru-CHx; simultaneously ruthenium metal could be oxidized with CO2 to give Ru-O-x and CO; and then, oxygen transfer from Ru-O-x to Ru-CHx took place to give CO and metallic ruthenium.
Distinct temperature increases in the catalyst bed for La2O3, Y2O3 and ZrO2 supports were observed with the introduction of CO2 pulses under Ar flow. On the other hand, a very small increase in the temperature of the catalyst bed was observed on Al2O3 These results indicate that CO2 reforming of CH4 with ruthenium loaded catalysts was strongly assisted by the activation of CO2 adsorbed on the basic sites. (C) 1999 Elsevier Science B.V. All rights reserved.

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Partial oxidation of methane to synthesis gas was carried out using supported iridium-nickel bimetallic catalysts, in order to reduce loading levels of iridium and nickel, and to avoid carbon deposition on nickel-based catalysts by adding iridium. The performance of supported iridium-nickel bimetallic catalysts in synthesis gas formation depended strongly upon the support materials. La2O3 gave the best performance among the support materials tested. Ir(0.25 wt%)-Ni(0.5 wt%)/La2O3 afforded 36% conversion of methane (CH4/O-2=5) to give CO and H-2 with the selectivities of above 90% at 800 degrees C, and those at 600 degrees C were 25.3% conversion of methane and CO and H-2 selectivities of about 80%, respectively. Reduced monometallic Ir(0.25 wt%)/La2O3 and Ni(0.5 wt%)/La2O3 catalysts did not produce synthesis gas at 600 degrees C. A higher conversion of methane was obtained by synergistic effects. The product concentrations of CO, H-2, and CO2, and CH4 conversion were maintained in high values, even increasing the space velocity of feed gas over Ir-Ni/La2O3 catalyst, indicating that rapid reaction takes place. As a by-product, a small amount of carbon deposition was observed, but carbon formation decreased with increasing the space velocity. On the other hand, with reduced monometallic Ni(10 wt%)/La2O3 catalyst, yield of synthesis gas and carbon decreased with increasing the space velocity. (C) 1999 Elsevier Science B.V. All rights reserved.

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Ethylbenzene was prepared from benzene and ethane, using platinum-loaded H-ZSM5 catalyst at 500 degrees C, giving the ethylbenzene and styrene space lime yields of 14.2 and 0.8 mmol h(-1) g(-1) of catalyst, respectively (benzene-based yields 6.9 and 0.4%).

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SHANXI SCIENCE & TECHNOLOGY PRESS  

Co-liquefaction of Yallourn coal (YL) with polyethylene (PE) was carried out in two stages at 250 - 425 degrees C under pressurized hydrogen with or without Fe(CO)(5)-S in 1-methylnaphthalene.
The product distribution (conversion : 73.0 %, preasphaltene : 3.8 %, asphaltene : 4.0 %, oil : 54.3 %, and gas : 11.0 %) was obtained in the two stage co-liquefaction without a catalyst at 350 degrees C for 30 min and at 425 degrees C for 30 min. As compared to single stage co-liquefaction at 425 degrees C for 60 min, the oil yield increased and the gas yield decreased. In the co-liquefaction with Fe(CO)(5)-S in two stages, the conversion (89.0 %) and the oil yield (59.8 %) were higher than those obtained in the co-liquefaction without the catalyst and in the single stage co-liquefaction with the catalyst.
These results seemed to show that the oil fraction produced from PE at 350 degrees C acted as a good solvent for the coal liquefaction at 425 degrees C with or even without the catalyst.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Gallium oxide is found to be an effective catalyst for the dehydrogenation of ethane to ethene in the presence of carbon dioxide at 650 degrees C, giving 18.6% ethene yield with a selectivity of 94.5%.

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Dehydrogenation of isobutane to isobutene was successufully carried out on iron loaded activated carbon catalyst at 873 K. Isobutane conversion of 48%, the yield of 40% and selctivity 80% were obtained with 0.3 mmol iron loaded on Ig of activated carbon, at 873 K with W/F of 25 g-cat-h/mol of isobutane. Cofeeding of carbon dioxide promoted dehydrogenation as compared to feeding bulk isobutane or isobutane and argon mixture. Hydrogen produced by dehydrogenation was transformed into water in the presence of carbon dioxide, and carbon dioxide was reduced to carbon monoxide. A redox cycle of Fe3O4 and metallic iron is suggested for the catalytic cycle in carbon dioxide by analyzing XRD and XPS. Carbon deposition was reduced under a carbon dioxide stream as compared with the reaction under argon atmosphere. (C) 1998 Elsevier Science B.V.

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In order to discuss the hydrogen transfer process in coal liquefaction with a catalyst in the presence of a donor solvent, hydroliquefaction of Yallourn, Wyoming, Illinois No.6, and Mi-ike coals and cracking of benzyl phenyl ether (BPE) were carried out in tetralin or tetralin/naphthalene mixed solvent under a hydrogen atmosphere with highly dispersed catalyst precursors such as Fe(CO)5-S, Mo(CO)6-S, and Ru3(CO)12. In the absence of the catalyst, more than 70 % of hydrogen was transferred from tetralin, as determined by the formation of naphthalene.In the presence of Mo(CO)6-S and Ru3(CO)12, however, the amount of hydrogen transferred from tetralin decreased to 15 - 40 % of the total hydrogen and that from gas phase increased to 60 - 85 % of the hydrogen required to stabilize coal fragment radicals even with an excess amount of tetralin.When the reaction was carried out in the tetralin/naphthalene mixed solvent, little hydrogenation of naphthaleneoccurred even with the active catalyst.This strongly supports the assertion that a decrease in the amount of naphthalene in the catalyzed liquefaction of coal in tetralin with a catalyst can be ascribed to the direct hydrogen transfer from molecular hydrogen to coal fragment radicals.In the presence of coal or benzyl phenyl ether, little or no hydrogenation of naphthalene occurred.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BALTZER SCI PUBL BV  

A partial oxidation of methane was carried our using iridium catalysts supported on several metal oxides. The productivity of the synthesis gas from methane was strongly affected by the choice of support oxides for the catalysts. The synthesis gas production proceeded basically via a two-step reaction consisting of methane combustion to give H2O and CO2, followed by the reforming of methane from CO2 and steam. Although the combustion and the reforming of methane from steam did not depend upon the catalyst support, a large variation in the catalytic activity fbr the reforming of methane from CO2 was observed over Ir catalysts with different supports. The support activity order in the reforming of methane from CO2 with iridium catalysts was as follows: TiO2 greater than or equal to ZrO2 greater than or equal to Y2O3 > La2O3 > MgO greater than or equal to Al2O3 > SiO2. The same order was observed in the synthesis gas production from the partial oxidation of methane.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Liquefaction of Spirulina, a high-protein microalga, afforded > 90 wt% of THF-soluble products and 60 wt% of hexane-soluble fractions, in the temperature range 300-425 degrees C under hydrogen in various organic solvents with highly dispersed catalysts. The oil yield increased from 52.3 to 66.9 wt% With Fe(CO)(5)-S catalyst at 350 degrees C for 60 min in tetralin under 5.0 MPa of hydrogen. Hydrogen activated by the dispersed catalyst contributed to an increase in oil yield. Liquefaction in water as solvent gave a higher oil yield of 783 wt% at 350 degrees C even under nitrogen. Liquefaction in toluene gave oil fractions of high carbon content and lower oxygen content, with a heating value of 32-33 MJ kg(-1). On the contrary, oil fractions obtained in water had a lower carbon content and higher oxygen content, with a lower heating value of 26 MJ kg(-1). The presence of moderate amount of water is considered to be effective for the production of oil of high heating value in high yield. FT-i.r. spectroscopy and gel permeation chromatograph, showed that production of oil fractions proceeded via thermal decomposition of polypeptides and hydrolysis by water produced during liquefaction in organic solvents. (C) 1997 Elsevier Science Ltd.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Reactions of 1,2-(1,1'-)dinaphthylethane (DNE) and 1,2-diphenylethane (DPE) in a hydrogen donor solvent in the absence or in the presence of highly dispersed catalysts such as Mo(CO)(6)-S and Ru(acac)(3) were carried out at 658 or 698 K under a hydrogen atmosphere in order to investigate quantitative hydrogen transfer process in the cracking of C-C bond in coal. Dinaphthylethane mainly produced 1-methylnaphthalene, and diphenylethane afforded benzene, toluene, and ethylbenzene as the major low molecular weight products. In addition, hydrogenation of DNE and DPE occurred. In the absence of a catalyst, more than 70 mol % of hydrogen was transferred from the hydrogen donor solvent. In the presence of Mo and Ru catalyst, the hydrogen required for stabilizing free radicals and hydrogenating aromatic rings was predominantly derived from gas phase without or with a small amount of the solvent. However, the amount of hydrogen transferred from gas phase considerably decreased and the amounts of hydrogenated products and decomposed products of DNE and DPE lowered with increasing concentration of the hydrogen donor solvent even with the dispersed Mo or Ru catalyst. The hydrogen donor solvent retarded the catalyzed cracking of DNE and DPE because of competitive adsorption of the model compound and the hydrogen donor solvent on the catalyst surface.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Petroleum Institute  

Reforming of heptane with CO2, using Ni and Ru catalysts was carried out. Ruthenium, supported on La2O3 exhibited high catalytic activity at 600°C in the CO2 reforming of heptane, but the activity decreased rapidly. Deactivation of the catalyst during reaction was reduced by adding LiOH(Li/Ru=3) to the catalyst, which eliminated carbon deposition. Ratio of CO/H2 was greater than that expected from the stoichiometric reaction of CO2 and C7H16. This is considered to be caused by the reverse water gas shift reaction, giving CO by reducing CO2 with H2 produced. To maintain higher catalytic activity, the formation of La2O2CO3 seems to be essential.

DOI： 10.1627/jpi1958.40.179

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Language：Japanese   Publisher：The Japan Institute of Energy  

DOI： 10.20550/jietaikaiyoushi.6.0_239

CiNii Books

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置換フェノール類の水素化脱酸素反応(HDO)を市販のNi-Mo/Al2O3触媒およびCo-Mo/Al2O3触媒を用いて流通式反応装置で検討した。Ni-Mo/Al2O3触媒での主生成物は芳香環水素化の後に脱酸素されることによって得られる置換シクロヘキサン類であったが、Co-Mo/Al2O3触媒での主生成物は芳香環からの直接脱酸素によるベンゼン類であった。3,4または5位にメチル置換されたフェノール類の反応性はメチル基の電子供与性効果によりOH基と触媒表面とのより強い相互作用が生じるため置換基が存在しないフェノールの反応性より増大する傾向が認められたが、メチル基の電子供与性による促進効果はCo-Mo/Al2O3触媒の方がNi-Mo/Al2O3触媒より顕著に認められた。 2,6位にメチル置換されたフェノール類の反応性は置換基の立体障害により触媒への吸着が阻害され、著しく低下した。この傾向もまた、Co-Mo/Al2O3触媒の方がNi-Mo/Al2O3触媒より明確に現れ、Ni-Mo/Al2O3触媒では芳香環の水素化後に脱水反応により脱酸素反応が起こるため、2,6位の置換基の影響を受けにくかったものと考えると、両触媒の作用機構の差異が説明される。

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Carbon dioxide gasification of various iron-loaded carbon species such as Yallourn coal char, carbon black, and activated carbon were investigated. Catalytic effect of iron was pronouncedly observed when less reactive carbons such as carbon black or activated carbon was gasified at 800 degrees C. Cyclic gasification in which a gasification agent and a product CO were fed alternately was carried out in order to enhance activities of iron catalyst. When appropriate intervals in the feeding of CO2 and CO was selected (CO2 75 s and CO 120 s), gasification rate increased considerably, even with the shorter effective gasification time. Moreover, instantaneous gasification of iron-loaded carbons occurred, if the iron-loaded carbons were treated with CO at 780 to 800 degrees C for 120 s before introducing CO2. Such phenomenon is called rapid gasification and is only observed when highly dispersed alpha-iron (elucidated by EXAFS) was produced on the carbon surface. The most significant rapid gasification was observed and about 70% of original carbon was gasified within 4 min at 800 degrees C, when 1.8 mmol of iron was loaded on 1 g of carbon black (surface area 101 m(2)/g).

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE PUBL B V  

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科研費特定領域研究

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An attempt to use carbon dioxide as a diluent and oxidant in the dehydrogenation of ethylbenzene to styrene was carried out over an activated carbon-supported iron catalyst (Fe 17 wt.-%) at 773-973 K, CO2/ethylbenzene = 50-70 mol/mol and W/F = 30-120 g h/mol. An addition of 20-30 mol-% lithium nitrate to iron resulted in a significant increase in the catalytic activity. The highest yield of styrene (40-45%) with more than 90% selectivity was obtained at a ratio of lithium to iron of 0.1-0.2 (mol/mol). In addition to styrene, carbon monoxide and water were formed as products. This indicated that the reaction proceeds via an oxidative dehydrogenation mechanism. Added lithium nitrate was converted into lithium ferrite during the treatment of an iron-lithium co-loaded activated carbon catalyst under carbon dioxide at 973 K. Lithium ferrite thus formed would be an active center of the reaction.

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Language：Japanese   Publisher：The Japan Institute of Energy  

DOI： 10.20550/jietaikaiyoushi.4.0_21

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In order to enhance dispersion of catalyst for coal hydroliquefaction, an iron-loaded Blind Canyon coal (Fe-BC(K)) was prepared by reducing iron ion with potassium borohydride (KBH4) in the presence of Blind Canyon coal. Hydroliquefaction of Blind Canyon coal (low pyrite content in coal) was carried out with an iron-loaded coal as catalyst in l-methylnaphthalene at 420 degrees C for 60 min under a hydrogen atmosphere (5.0 MPa cold). Iron-loaded coal Fe-BC(K) showed the highest coal conversion and oil yield amounting to 92.0 and 43.9%, respectively, among the catalysts employed in this study. Dispersed iron species on Fe-BC(K) was assigned as alpha-Fe by the X-ray diffraction analysis. Iron dispersed coal, Fe-BC(K) afforded higher coal conversion and oil yield than metallic iron powder prepared by the same method in the absence of coal. The catalytic activity could only be enhanced when the reduction of iron ion was performed in the presence of coal to give highly dispersed iron species. This was proved by X-ray diffraction analyses of line broadening. Effects of catalyst level of iron and reaction time on the product distribution, on the amount of hydrogen transferred, and on the composition of the solvent were examined.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In order to discuss quantitative hydrogen-transfer process, cracking of benzyl phenyl ether (BPE) and dibenzyl ether (DBE) in tetralin using highly dispersed catalyst precursors such, as Fe(CO)5, MO(CO)6, and Ru(acac)3 was carried out at 648 K under a hydrogen atmosphere. Identified products from cracking of BPE were benzene, toluene, phenol, diphenylmethane, 1,2-diphenylethane, isomeric (hydroxyphenyl)phenylmethanes, benzyltetralins, and benzylnaphthalenes, and identified products from DBE were benzaldehyde and benzyl alcohol in addition to the above substances except phenol. The required amount of hydrogen to stabilize free radicals from BPE was in good agreedment with the amount of hydrogen transferred from tetralin and gas phase. In the absence of a catalyst, more than 90 mol % of hydrogen was transferred from tetralin. In the presence of Mo(CO)6-S, the amount of hydrogen transferred from tetralin decreased to around 15 mol % of hydrogen and the amount of hydrogen transferred from the gas phase increased to around 85 mol % of hydrogen required for stabilizing free radicals. Similar observation was obtained in the reaction with DBE without or with added catalysts. In the reaction of BPE or DBE in tetralin, hydrogenation of naphthalene to tetralin did not occur or occurred slightly even with active catalysts. The direct hydrogen transfer from molecular hydrogen to radicals occurred in the cracking of BPE and DBE with active catalysts such as dispersed Ru or Mo.

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Language：Japanese   Publisher：触媒学会  

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Language：English   Publisher：CHEMICAL SOC JAPAN  

We found that oxidized diamond played a significant role to improve catalyst performance of Cr2O3 catalyst during the dehydrogenation of C2H6 to C2H4 in the presence of CO2.

DOI： 10.1246/cl.2000.1100

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Language：English   Publisher：ELSEVIER SCIENCE BV  

Partial oxidation of methane to synthesis gas was carried out using supported iridium catalysts. The performance of supported iridium catalysts in synthesis gas formation depended strongly on the support materials. Ir(5 wt%)/TiO2 afforded 25% conversion of methane (CH4/O-2=5) to give CO and H-2 With the selectivity of above 80% at 600 degrees C. Ir/TiO2 catalyst gave a CO-to-H-2 ratio of 2.0, as expected from the stoichiometric reaction. No carbon deposition was observed with the supported TiO2, and a constant activity was exhibited for at least 15 h, The synthesis gas yield with Ir/TiO2 catalyst was the same as supported Ph catalyst, which is reported to be the best catalyst for this reaction. The active species of Ir/TiO2 catalyst was found to be metallic iridium by XPS analyses. (C) 1998 Elsevier Science B.V.

DOI： 10.1016/S0926-860X(98)00020-9

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Language：English   Publisher：BALTZER SCI PUBL BV  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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