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Ring-hydrogenation of 4-propylphenol (4-PP) to 4-propylcyclohexanone, cis- and trans-4-propylcyclohexanols proceeded over graphite-supported palladium catalysts (Pd/G) in aqueous ethanol solution a...

Solvolysis of benzyl phenyl ether (BPE), which is a model compound of lignin ether linkage, was studied in an aqueous ethanol solution, which can be obtained from bioethanol, under high-pressure...

Synthesis of platinum nanoparticles intercalated between layers of commercially available graphite powder samples possessing surface area values ranging from 20 to 750 m2 g-1 was attempted by the insertion of platinum chloride between the layers followed by hydrogen reduction. Platinum nanosheets with 1-4 nm thickness and 5-300 nm width and hexagonal holes were obtained for the graphite powder with 20 m2 g-1 independent of the platinum loadings (5, 10, and 15 wt%). Platinum nanosheets with the similar size (1-4 nm thickness and 5-300 nm width) and hexagonal holes were formed for graphite powder with 120 and 300 m2 g-1 with only 15 wt% platinum loading, but not for 5 and 10 wt% platinum loadings. Interestingly, for the graphite powder with higher surface area of 500 and 750 m2 g-1, platinum nanosheets were not formed. Platinum nanosheets intercalated between graphite samples were evaluated for cinnamaldehyde hydrogenation in supercritical carbon dioxide solvent. High cinnamyl alcohol selectivity was obtained for the platinum nanosheets intercalated between graphite layers having surface area of 20 m2 g-1; however, hydrocinnamaldehyde selectivity was high for the platinum nanosheets intercalated between graphite samples having surface area of 120 m2 g-1.

Spherical palladium nanoparticles between graphite layers were prepared by the intercalation of palladium chloride followed by its reduction between graphite layers. The palladium particles interca...

The ring hydrogenation of 4-propylphenol in aqueous ethanol solution was studied over graphite- and activated carbon-supported palladium catalysts (Pd/G and Pd/C) with 0.1–5 wt % of palladium loadi...

The effect of molecular structure on the traction properties of polyglycol oils was investigated using a traction tester, and in-situ observation of the oil film was performed with a micro-Fourier transform infrared spectrometer under elastohydrodynamic lubrication conditions. The sample oils used were polypropylene glycol (PPG) diol, PPG triol, PPG dimethyl ether, PPG diester, PPG diamine, PPG triamine, and poly-α-olefin. The traction coefficient and oil film thickness of the sample oils were sensitive to the functional group at the terminal of the molecule. The sample oil containing polar functional group is larger in oil film thickness and traction coefficient than non-polar hydrocarbon oil, poly-α-olefin. These results suggest that the hydrogen bonding of functional groups was strengthened by high pressure in the Hertzian contact region. Moreover, the effect of water in the sample oils on the traction behavior was discussed. Water was dissolved into the sample oils from the atmosphere during the lubrication test, and it is implied that water in PPG diamine affect the traction coefficient.

Alcoholysis of benzyl phenyl ether to various aromatic compounds was studied in high-temperature aqueous methanol solution under high-pressure carbon dioxide conditions. The products formed included benzyl methyl ether, benzyl alcohol, phenol and toluene. As high as 70.7 ± 0.2% yield of monocyclic aromatic hydrocarbon with 16.1 ± 0.3% yield of benzyl methyl ether was obtained by treating benzyl phenyl ether with an aqueous solution with 0.2 molar fraction of methanol, under 17.7 MPa carbon dioxide for 1 h at 573 K.

In situ observation of lubricant films formed with greases was carried out at EHL conditions with a micro-FTIR. Three urea compounds were used as a thickener and 12 mass percent of the thickener was added in PAO, respectively. From the IR spectra, CH and NH stretching vibration peaks were observed from urea greases. The film thickness and the concentration of thickener were estimated from the absorbance of CH and the ratio of absorbance of NH and CH. Two-dimensional distribution of the thickness and the concentration around Hertzian contact was obtained at the resolution of 50 μm. The thickener of urea grease was concentrated on ball and disk surfaces. It was found that the concentrate on thickener at Hertzian contact region was dependent on thickener itself. Time dependence of the thickness and the concentration at Hertzian contact were obtained at the resolution of 45 s under shearing conditions. The film thickness of urea greases at Hertzian contact was greatly decreased by shearing and the film thickness and the concentration were recovered when the condition was changed to rolling. This behavior was supposed with detachment and growth of the adhered film of the thickener. Lubricating characteristics of urea greases were discussed based on the concentration of thickener at Hertzian contact.

In this work, we study physical and mechanical properties of oxide films formed on AZ91D magnesium alloy by plasma anodization at different temperatures. It is found that the higher the electrolyte temperature, the lower is the breakdown voltage of oxide layer. This is probably because films formed at higher temperatures are thinner and denser. Moreover, electrolyte temperature plays an important role in the physical properties of the films. As the electrolyte temperature increases from 20 to 50℃, the hardness of the oxide layer increases. Friction test against steel balls indicates that wear scars become narrower for films formed at higher temperatures because the films are harder, as indicated by the Vickers hardness. The thinner and denser nature of the oxide film formed at 50°C is also advantageous for heat transfer when film is used as a heat sink. Laser flash test results show very fast heat transfer for AZ91D with plasma anodized oxide layer formed at higher temperatures.

Disk-shaped metal particles having 1–3 nm thickness and 1–14 nm diameter were prepared by the reduction of iridium chloride intercalated between graphite layers. These iridium nanodisks between gra...

Insertion of sheet-type platinum particles (platinum nanosheets) between graphite layers was achieved by a thermal treatment of a mixture of platinum chloride (IV) and graphite powder (natural graphite or artificial graphite) under 0.3 MPa of chlorine at 723 K, followed by the treatment under 40 kPa of hydrogen pressure. Similar platinum nanosheets, which were 1-3 nm in thickness and 100-500 nm in width and had a number of hexagonal holes and edges with 120° angle, were formed between the layers of both natural graphite or artificial graphite; however, their location in the graphite layers depended on the type of graphite used. A number of platinum nanosheets were observed in the edge region of natural graphite particles which have flat surface. On the other hand, a number of platinum nanosheets were found inside and away from the edge of the artificial graphite particles especially in the vicinity of the cracks. Both the platinum nanosheet-containing artificial and natural graphite samples showed high selectivity to cinnamyl alcohol in cinnamaldehyde hydrogenation under supercritical carbon dioxide conditions, while spherical platinum particles, which were located on the surface of natural and artificial graphite, showed lower selectivity.

Synthesis of benzyl methyl ether from benzyl alcohol and methanol in high-temperature carbonic water was studied in a batch reactor. Benzyl methyl ether formation was not observed by reacting benzyl alcohol with only methanol under supercritical conditions at 573 K. On the other hand, benzyl methyl ether was formed by the treatment of benzyl alcohol in an aqueous methanol solution at 573 K. 12% of benzyl methyl ether yield was obtained in aqueous methanol solution (methanol to water molar ratio of 0.025 mol/0.11 mol) at 573 K in 60 min and the yield enhanced to 33% by the addition of 18 MPa of carbon dioxide to the aqueous solution. As the etherification is an acid catalyzed reaction, the protons derived from the dissociation of water molecules could be responsible for the etherification of benzyl alcohol in an aqueous methanol solution at 573 K. The enhancement of benzyl methyl ether yield by the addition of carbon dioxide in aqueous methanol solution is caused by the increase of the number of protons derived from carbonic acid, which is formed in high-temperature liquid water under high-pressured carbon dioxide.

Abundant labdatriene derivatives, named amberene [15,19,20-trinor-5,7,9-labdatriene (or 1,6-dimethyl-5-isopentyltetralin) (1)] and 1-methylamberene [15,20-dinor-5,7,9-labdatriene (or 1,1,6-trimethyl-5-isopentyltetralin) (2)] were isolated from the methanol extract of Kuji amber by HPLC. The structures were elucidated by spectral analyses including EIMS, 1D and 2D NMR and some previous assignments corrected.

Cinnamaldehyde hydrogenation behaviors of platinum nanosheets intercalated between graphite layers (Pt-GIC) were studied and compared with those of platinum particles on graphite surface (Pt/Gmix) ...

Furfural was directly obtained from bamboo powder in water–toluene biphasic solvents at 443 K over a chabazite-type (CHA) zeolite prepared with an interzeolite conversion method from a faujasite-type zeolite. The CHA zeolite was effective for the hydrolysis of hemicellulose fraction in ball-milled bamboo powder to xylose and selective dehydration of xylose to furfural.

Platinum chloride (IV) was intercalated between graphite layers with third stage structure by the treatment of a mixture of platinum chloride and graphite powder under 0.3 MPa of chlorine at 723 K....

Graphite-supported platinum catalysts (Pt/G) were highly active for the hydrogenolysis of benzofuran to o-ethylphenol in aqueous ethanol solution at 523 K without using any external hydrogen gas. The hydrogenolysis activities and selectivity to o-ethylphenol in ethanol solution over Pt/G were higher than those with a conventional method using externally supplied hydrogen gas. Both water and ethanol were indispensable for the hydrogenolysis in aqueous ethanol solution at 523 K.

Platinum nanosheets between graphite layers were prepared by a thermal treatment of the mixture of platinum chloride (IV) and graphite powder under 0.3 MPa of chlorine at 723 K for 7 days, followed by the reduction under 40 kPa of hydrogen at 573 K for 1 h. Two-dimensional platinum metal nanosheets of 1-3 nm thickness and of 100-200 nm width were intercalated between graphite layers (Pt-GIC). The platinum nanosheets had a number of hexagonal holes and edges with angle of 120°. Liquid phase hydrogenation of cinnamaldehyde (CAL) was studied over Pt-GIC which was compared with that over platinum metal particles supported on graphite layers (Pt/Gmix). The conversion of cinnamaldehyde over Pt-GIC was lower than that over Pt/Gmix; however, the selectivity to cinnamyl alcohol (COL) was higher than that over Pt/Gmix. For similar CAL conversion of around 25% (in 60 min over Pt-GIC and 15 min over Pt/Gmix), the COL selectivities over 5 and 10 wt% Pt-GIC (56 and 54%) were higher than those over 5 and 10 wt% Pt/Gmix (33 and 19%).

The aromatic hydrogenation of 4-propylphenol to 4-propylcyclohexanone, cis- and trans-4-propylcyclohexanols proceeded over a charcoal-supported palladium catalyst (Pd/C) in water–ethanol cosolvent ...

The correlation between molecular interaction and traction properties was investigated using a traction tester and in situ observation of elastohydrodynamic lubrication film with a micro-Fourier transform infrared spectrometer. The sample oils used were polypropylene glycols (PPGs) with the end-group of alcohol or ether and a synthetic hydrocarbon oil, poly-α-olefin. From the traction tests, it was found that the traction coefficient of PPG was sensitive to the end-group. PPG with alcohol as the end-group showed a higher traction coefficient than that with the ether group. In situ observation with a micro-Fourier transform infrared was performed in order to investigate the molecular interaction of the lubricant oil. It was found that the hydrogen bonding of hydroxyl groups in PPG was strengthened by high pressure in the Hertzian contact region. These results suggest that the rheological properties in the elastohydrodynamic lubrication contact region were affected by the strengthened hydrogen bonding. Copyright © 2014 John Wiley & Sons, Ltd.

Intramolecular dehydration of erythritol to 1,4-anhydroerythritol proceeded in liquid water at 573 K. The initial formation rate and final yield of 1,4-anhydroerythritol were 0.50 mmol h−1 and 71%, respectively. Addition of carbon dioxide up to the pressure of 17.7 and 24.8 MPa to water solvent at 573 K, the initial product formation rates dramatically increased to 1.45 and 2.10 mmol h−1, respectively; however, the final yields were almost the same as 73 and 71%, respectively. These results showed that the protons derived from carbonic acid catalyzed the intramolecular dehydration and the concentration of proton increased with an increase in the carbon dioxide pressure introduced.

In this work, we have investigated the infrared spectra of polar lubricant in order to explore the molecular interaction under high pressure and temperature conditions using diamond anvil cell. Polypropylene glycol and oleic acid were used as base oil and additive, respectively. Stretching vibration mode of polar functional groups, such as νO–H and νC═O, was found to be sensitive to pressure and temperature. The peak positions of the vibration mode were shifted clearly to lower wavenumber as pressure increases, and temperature increase induced a slight shift to higher wavenumber. These results indicate that hydrogen bonding between lubricant molecules of base oil and additive was influenced by pressure and temperature. And furthermore, the dependency of the peak shift was discontinuous and affected mainly by pressure. These results imply a structural change on the basis of the molecular interaction of the lubricating molecules at elastohydrodynamic lubrication contacts. Copyright © 2013 John Wiley & Sons, Ltd.

The tribological properties of room temperature ionic liquids containing tetraalkylphosphonium cations were evaluated on the basis of the chemical structure of their salts. The tribochemistry of these ionic liquids was discussed on the basis of the results of tribo-tests and surface analyses. The tribological properties of the tetraalkylphosphonium salts examined in this work were observed to be better than those of 1,3-alkylimidazolium salts. The structure of the alkyl group in the phosphonium cation also has a slight effect on the tribological properties of the salts. During a friction test carried out under low-load conditions, the phosphonium cation was oxidized to phosphate to form a boundary film. This film inhibited the reaction of the bis(trifluoromethanesulfonyl)amide anion that yielded metal fluoride on the rubbed surfaces. The combination of the phosphonium cation with a phosphate anion or thiophosphate anion resulted in a better lubricant than 1,3-alkylimidazolium bis(trifluoromethanesulfonyl)amide. The reactions of the phosphate anion and thiophosphate anion yielded a phosphate boundary film that exhibited better tribological properties than those of the fluoride boundary film.

Dispersion-type lubricants formulated with calcium carbonate were experimentally studied to achieve improved hot-rolling characteristics of stainless steel. Two types of lubricants; over-based calcium sulfonate dispersed in oil (fluid type; FT) and calcium carbonate dispersed in grease (semi fluid type; ST) were prepared. ST containing larger particles of calcium carbonate exhibited a better lubricity in rolling of steel than FT. Although the particle size of calcium carbonate powder is about 1 μm, the dispersed state was stable in ST. Following the rolling tests, the surfaces of tribo-films were analyzed using XPS and TOF-SIMS. A lubrication model with calcium carbonate particles was proposed based on the surface analysis.

In the present work, the stabilisation of hydrogen bonding of polypropylene glycol at elastohydrodynamic lubrication (EHL) contact was investigated by in situ observation with a micro-Fourier transform infrared spectrometer, and the effect of hydrostatic pressure on infrared (IR) spectra was confirmed using a diamond anvil cell. Polypropylene glycols with different molecular weights were used as sample oils. Polypropylene glycol molecules interact with themselves by hydrogen bonding with their hydroxyl groups. Stability of the hydrogen bonding is observed by IR peak shift of the O–H stretching mode (3400–3700 cm−1). In the case of the dynamic condition under EHL, the C–H stretching mode shifted to a higher wavenumber, whereas the O–H stretching mode shifted to a lower wavenumber at the Hertzian contact region. This result means that the hydrogen bonding of polypropylene glycol was stabilised under high pressure, and the stabilisation of hydrogen bonding by pressure was dependent on the molecular weight of polypropylene glycol. Copyright © 2010 John Wiley & Sons, Ltd.

Tribochemistry of metal nitride coatings in the presence of alcohol was investigated by using a stable isotopic tracer. The tribological properties were evaluated by a ball-on-disk type tribo-tester with steel ball and metal nitride coated disk under reciprocating motion. It was found that the friction coefficient of CrN was approximately 60% lower than that of TiN. On the other hand, TiN afforded lower wear than CrN. Considerable amount of deposit was observed on TiN. The rubbed surfaces were chemically analyzed by means of time-of-flight secondary ion mass spectroscopy (TOF-SIMS). In order to eliminate the undesirable fragment ions originated from organic contaminations in TOF-SIMS analysis, pentadeuterioethanol was used as an isotopic tracer. It was found that CrN reacted with alcohol to provide chromium ethoxide as boundary film. On the other hand, transferred Fe ion from the ball was the major contents on rubbed surfaces of TiN coatings.

The molecular interaction of oleic acid in different base oils at Elastohydrodynamic lubrication (EHL) contact was investigated by means of in-situ observation with micro-Fourier Transform Infrared Spectrometer (FTIR). Moreover, the effect of hydrostatic pressure was confirmed using a diamond-anvil cell (DAC). Poly-α-olefin (PAO) with non-polar, and Polypropylene glycol and Polybutylene glycol (PPG and PBG) which have ether group were used as base oil. When PAO was used, oleic acid interacts with itself to form a dimer. On the other hand, oleic acid interacts with PPG and PBG and exists mainly as a monomeric moelcule. The IR peak of C = O stretching mode of oleic acid dimmer was shifted to lower wavenumber at EHL contact region. The peak shift was not obvious in the case of the monomer. This result means that the hydrogen bonding of the dimer was stabilized under high pressure, but the hydrogen bonding of monomer was not. Copyright © 2010 John Wiley & Sons, Ltd.

A nascent surface has high activity to catalyze the decomposition of lubricants under boundary lubrication conditions. The effects of sulfur-containing, nitrogen-containing, phosphorus-containing additives and phosphate-containing ionic liquid were investigated on the decomposition of synthetic hydrocarbon oil (multialkylated cyclopentane, MAC). The decomposition processes of the lubricants on the nascent surface of bearing steel AISI 52100 were investigated using a ball-on-disk friction tester in a vacuum chamber with a quadrupole mass spectrometer. Three parameters related to the decomposition process were observed: the induction period for the decomposition, the desorption rate of gaseous products, and the critical load for the activation of the decomposition. The order of efficiency of additives in extending the induction period was: sulfur-containing additive (S)

The role of di-tert-dodecyl disulfide as an additive in the decomposition process of hydrocarbon oil on the nascent surface of bearing steel 52100 was investigated by a ball-on-disk friction tester in a vacuum chamber with a quadrupole mass spectrometer (Q-MS). After the formation of a nascent surface, hydrogen and gaseous hydrocarbons desorbed as tribochemical reaction products. The desorption rate of gaseous hydrocarbons decreased significantly when the additive was introduced. The additive prolonged the induction period of the decomposition. XPS and ToF-SIMS analysis revealed that additive molecules and lubricant molecules competitively chemisorbed on the nascent surface and reaction occurred by the formation of iron sulfide, which poisoned the catalytic activity of active sites leading to deactivation. As a result, decomposition of hydrocarbon oil decreased significantly.