Yoshinobu Takegami

Chemical structure of tar-sand bitumens by 13C and 1H n.m.r. spectroscopic methods

Abstract 1 H and 13 C n.m.r. spectra of Athabasca, Cold Lake and Orinoco tar-sand bitumens, their columnchromatographed fractions, their vacuum distillates, their vacuum residues and the columnchromatographed fractions of the vacuum residues were determined to investigate the average molecular structures of these materials. The most probable average structural parameters were calculated without making any assumptions, and average structural models for the Athabasca series are proposed. Compared with corresponding petroleum fractions, tar-sand bitumens contain shorter, paraffinic straight-chains and are abundant in alicyclic carbon atoms. This trend is more marked in the saturate fractions or vacuum distillates. The vacuum residues of tar-sand bitumens contain relatively longer, paraffinic straight-chains than the original bitumens.

Structural investigation on column-chromatographed vacuum residues of various petroleum crudes by 13C nuclear magnetic resonance spectroscopy

Proton and carbon-13 nuclear magnetic resonance spectroscopy of various vacuum residues and their fractionated samples were carried out to investigate average molecular structures. The structural parameters derived from carbon distribution agreed with those derived from p.m.r. within experimental error. In the aliphatic region of the c.m.r. spectra, characteristic peaks assignable to (CH2)n − n ≧ 6 (29.7 ppm) and CH3CH2CH2CH2 (14.1 ppm) etc. can be observed. The relative intensities of these peaks suggest that the methylene chain contained in vacuum residues is much longer ((CH2)n − n ≧ 12) than has been considered previously. Using the information about the aliphatic region of the c.m.r. spectrum and the structural parameters, an average structural model was deduced.

Coal liquefaction using iron complexes as catalysts

Hydroliquefaction of Japanese Miike and Taiheiyo coals was carried out using various iron complexes as catalysts in tetralin at 375–445 °C. Iron pentacarbonyl (Fe(CO)5) showed the highest catalytic activity, increasing coal conversion by about 10% at 425 °C under an initial hydrogen pressure of 5 MPa. Amounts of hydrogen transferred to coal increased from 1.4–2.3 wt% of daf coal in the absence of the catalyst to 2.5–4.2 wt% of daf coal in the presence of Fe(CO)5 at 425 °C.

Alcohol synthesis from syngas on ruthenium-based composite catalysts

Abstract Hydrogenation of carbon monoxide on Ru-Mo-Na and related catalysts has been studied at 255°C under 86 kg cm −2 . A series of straight chain primary alcohols together with hydrocarbons were formed on these catalysts. A Ru-Fe-Na/A1 2 0 3 catalyst had a considerable activity for the formation of higher alcohols; however, it gave a low alcohol selectivity. Both catalysts of Ru-Mo-Na/active carbon and Ru-Mo-La/A1 2 0 3 showed a high activity for alcohol synthesis; however, more than 70% of the producted alcohols was methanol. The Ru-Mo-Na/A1 2 0 3 catalyst prepared from RuC1 3 as the ruthenium source was preferrable to the ouher catalysts, because it showed an appreciable activity for alcohol synthesis and had a good selectivity for higher alcohols.

Low temperature catalytic graphitization of hard carbon

Abstract Artificial resins producing non-graphitizing carbons such as divinyl benzene polymer and condensates of furfuryl alcohol or furfural, were heat treated at temperatures between 1400 and 2300°C with an addition of various kinds of metallic compounds. Using X-ray diffraction it was found that carbons thus obtained were highly graphitized. The catalytic graphitization starts at temperatures between 1400 and 1500°C and is accompanied by an appearance and disappearance of several unidentified diffraction peaks, which may originate from some kind of intermediate complexes of carbon and metals.

Direct alcohol synthesis from syngas on Ru−Mo−Na/Al2O3 catalysts: effects of physical properties of alumina supports

Abstract Direct synthesis of alcohols from syngas on Ru Mo Na/Al 2 O 3 catalysts was investigated at 255°C under 86 kg cm −2 . Relationships between properties of the alumina support, CO adsorption ability of the catalyst, and its alcohol synthesis activity are discussed. For the support with a large BET surface area, the dispersion of supported Ru was proportional to the cubic root of the BET surface area of the support. Specific activity for alcohol synthesis increased with decreasing dispersion. The highest alcohol synthesis activity (437 g/l.h) was achieved by the catalyst supported on the alumina obtained by calcination of bayerite at 900°C.

Enhancement of oxygen transmission in the oxidation of active carbon by the composite catalyst

Abstract Low-temperature oxidation of active carbon in the temperature range 200–500 °C on a series of composite catalysts was studied. The oxidation state of the catalyst metal during the reaction was determined at various temperatures by a dynamic adsorption method. The three-component catalyst, Co as the main component of the catalyst combined with small amounts of La 2 O 3 and Pt, exerted a synergistic effect on the oxidation activity. The oxidation activities were more enhanced at more reduced states of the catalyst during the reaction. When Pt particles were dispersed close to but separate from Co + La 2 O 3 particles, the three-component catalyst accelerated the oxygen uptake and also the oxygen transfer to the carbon. A two-step oxygen transmission mechanism, interpreting the acceleration of oxygen transmission to the active carbon through the Pt and then Co + La 2 O 3 , is proposed.

Control of pore structures of γ-alumina by the calcination of boehmite prepared from gibbsite under specific conditions

Abstract Hydrothermal treatment of gibbsite to boehmite and subsequent calcination to form alumina have been investigated. The aqueous solution of 0.5 – 1.0 M concentration alkali metal salts, such as NaNO3, KNO3 and LiNO3,accelerated boehmite formation and the gibbsite conversion to boehmite could be controlled with good reproducibility. The resulting boehmite had a good thermal resistance and γ-alumina with a BET surface area of ~100 m2 g−1 could be obtained by calcination, even at moderate temperatures of 500 – 700°C.

Complete oxidation of active carbon at low temperatures by composite catalysts

Abstract The reaction between oxygen and active carbon was studied at 500°C. Various composite catalysts having an iron-group metal as the main component were supported on active carbon. The synergistic effect of the oxidation activity was widely observed in the composite metal-metal oxide catalyst/carbon system. Several active carbons were studied in this catalyzed oxidation and the oxidation rate decreased with decreasing surface area of carbon materials. The rate-determining step of this reaction was considered to be the surface-diffusion rate of oxygen. Enhancement of oxygen transmission by active composite catalysts resulted in promotion of the reaction.

The reducive amination of phthalaldehyde by tetracarbonylhydridoferrate : Synthesis of 2-arylisoindoles

Abstract Phthalaldehyde reacted with primary amines in the presence of tetracarbonylhydridoferrate under mild conditions to give 2-substituted isoindoles and/or isoindolines in good to excellent yields. Aliphatic amines gave selectively the isoindolines but aromatic amines had a great tendency to the isoindoles. 2-(2-Tolyl)-, 2-(4-tolyl)-, 2-(4-methoxyphenyl)-, 2-(3-chlorophenyl)-, 2-(4-chlorophenyl)- and 2-(3,4-dichlorophenyl)-isoindole were prepared by this method.