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Two-dimensional hydrogen boride (HB) sheets were recently demonstrated to act as a solid acid catalyst in their hydrogen-deficient state. However, both the active sites and the mechanism of the catalytic process require further elucidation. In this study, we analyzed the conversion of ethanol adsorbed on HB sheets under vacuum during heating using in situ Fourier transform infrared (FT-IR) absorption spectroscopy with isotope labelling. Up to 450 K, the FT-IR peak associated with the OH group of the adsorbed ethanol molecule disappeared from the spectrum, which was attributed to a dehydration reaction with a hydrogen atom from the HB sheet, resulting in the formation of an ethyl species. At temperatures above 440 K, the number of BD bonds markedly increased in CD3CH2OH, compared to CH3CD2OH; the temperature dependence of the formation rate of BD bonds was similar to that of the dehydration reaction rate of ethanol on HB sheets under steady-state conditions. The rate-determining step of the dehydration of ethanol on HB was thus ascribed to the dehydrogenation of the methyl group of the ethyl species on the HB sheets, followed by the immediate desorption of ethylene. These results show that the catalytic ethanol dehydration process on HB involves the hydrogen atoms of the HB sheets. The obtained mechanistic insights are expected to promote the practical application of HB sheets as catalysts.

Squalene structurally resembles petroleum resources, and is efficiently produced by Aurantiochytrium mangrovei, a microalga, and could be used effectively as an alternative oil resource. An efficient heterogeneous catalyst system for the epoxidation of squalene was developed, comprising the heterogeneous catalyst [N(C6H13)4]3[PW4O8(O2)8] for the successful epoxidation of squalene with H2O2 in t-BuOH. The addition of the tetraalkylammonium salt [N(C6H13)4]Cl, and H2O2 as the oxidant allowed quantitative epoxidation of squalene.

Radon and thoron exhalation rates from the ground surface were estimated in three islands of Okinawa Prefecture, a subtropical region of Japan. In situ measurements of the exhalation rates were conducted at a total of 88 points using an accumulation technique with a ZnS(Ag) scintillation detector. The radon and thoron exhalation rates were calculated to be 1-137 (arithmetic mean: 21) mBq m(-2) s(-1) and 32-6244 (1801) mBq m(-2) s(-1), respectively. In the surface soil samples collected at 53 measurement points, (238)U and (232)Th series concentrations were estimated to be 17.9-254.0 (64.0) Bq kg(-1) dry and 17.8-136.1 (58.8) Bq kg(-1) dry, respectively. The maximum rates and concentrations were observed in the dark red soil area. Recent studies strongly suggest that the base material of the soils may be the eolian dust derived from the southeastern part of China, a high background radiation area. The eolian dust is, therefore, considered to be an enhancer for the radon and thoron exhalations in Okinawa.

The morphology and NO reactivity of Rh deposited on a thin Al2O3 film were studied by means of x-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and noncontact atomic force microscopy. The NO dissociation activity of the Rh deposited on the Al2O3 surface was higher than that of Rh(111). The NO dissociation kinetics and the NO and CO adsorption properties of the Rh/Al2O3 surface indicated that the surface structure of the supported Rh mainly consisted of a (100) face. The supported Rh existed as small particles on the step sites of the Al2O3 surface. Thus, the authors believe that the low-coordinated step sites of Al2O3 played a role in formation of the (100) surface structure.

The effect of Zn in copper catalysts on the activities for both CO2 and CO hydrogenations has been examined using a physical mixture of Cu/SiO2+ZnO/SiO2 and a Zn-containing Cu/SiO2 catalyst or (Zn)Cu/SiO2. Reduction of the physical mixture with H2 at 573–723 K results in an increase in the yield of methanol produced by the CO2 hydrogenation, while no such a promotion was observed for the CO hydrogenation, indicating that the active site is different for the CO2 and CO hydrogenations. However, the methanol yield by CO hydrogenation is significantly increased by the oxidation treatment of the (Zn)Cu/SiO2 catalyst. Thus it is concluded that the Cu–Zn site is active for the CO2 hydrogenation as previously reported, while the Cu–O–Zn site is active for the CO hydrogenation.

The atomic structure of a MnO-deposited Rh(100) surface was studied using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). The STM image of MnO/Rh(100) at a Mn coverage of 0.80 showed two hexagonal domains rotated by 90° with respect to each other. One of the unit vectors for these hexagonal domains had the same direction as the unit vector of the Rh(100) substrate, suggesting that these hexagonal domains grow in the [011] or [011] direction of Rh(100). An averaged spacing of 3.1 A was obtained by the STM for the nearest-neighbor atoms of the hexagonal layer. The LEED pattern supported the presence of two hexagonal domains rotated by 90° by 12 extra spots in addition to the spots of the Rh(100) substrate. A lattice constant of 3.1 A for the hexagonal domain measured by LEED coincided with that measured by STM. The hexagonal layer was found to be stable at 800 K. Although the Mn/Rh(100) surface showed no hexagonal LEED pattern or hexagonal STM image, the oxidation of the Mn/...

The kinetics of formate synthesis from CO2 and H2 and from formate decomposition on Cu/SiO2 were studied by temperature-programmed decomposition experiments and compared with those reported for Cu(111), Cu(110), and Cu(100) surfaces under similar reaction conditions. The initial rate of the formate synthesis from 380 Torr CO2/380 Torr H2 at 323–353 K over the Cu/SiO2 catalyst was in good agreement with those on Cu(111) and Cu(110). At 353 K, for example, the initial rate was measured to be 5.3×10−4 molecules site−1 s−1. The apparent activation energy was determined to be 58.8 kJ mol−1, which was also comparable with those obtained for Cu(111) (54.6–56.6 kJ mol−1), Cu(110) (59.8 kJ mol−1), and Cu(100) (55.6 kJ mol−1). The decomposition rate of formate was first-order in formate coverage, and the rate constant was 1.13×10−4 s−1 at 384 K. The activation energy and the pre-exponential factor were determined to be 115.7 kJ mol−1 and 5.38×1011 s−1, respectively, in good agreement with those obtained for Cu(111), 107.9–112.8 kJ mol−1 and (1.87–4.02)×1011 s−1, rather than those for Cu(110) (145.2 kJ mol−1 and 1.22×1016 s−1) and Cu(100) (130–155.0 kJ mol−1). The promotional effect of H2 upon the decomposition of formate was observed on the Cu/SiO2 catalyst as observed for Cu(111) but not for Cu(110). The decomposition rate of formate on Cu/SiO2 was promoted by a factor of 6 at an H2 pressure of 457 Torr. These kinetic results clearly indicate that the surface of Cu particles supported on SiO2 comprises Cu(111) planes. Equilibrium formate coverage on Cu/SiO2 during the hydrogenation of CO2 was well reproduced by the calculated coverage based on the kinetics of the formate synthesis and the formate decomposition. However, the equilibrium formate coverage on Cu/SiO2 was greater than that measured for Cu(111) under the same reaction conditions because the hydrogen-promoting decomposition rate on Cu/SiO2 is less than that on Cu(111). This is explained by a decrease in hydrogen coverage on Cu surfaces of the Cu/SiO2 catalyst caused by the spillover of hydrogen atoms from Cu onto the SiO2 surface. Thus, the effect of SiO2 was observed in the hydrogen-promoting decomposition kinetics on Cu.

The adsorption structure of formate species on Cu(111), prepared by two different methods, was studied using ultrahigh vacuum scanning tunneling microscopy (UHV-STM), that is, the synthesis by the hydrogenation of CO2 at atmospheric pressure and the adsorption of formic acid on an oxygen-precovered Cu(111). Linear chains of formate molecules were imaged by the hydrogenation of CO2 by STM at low formate coverage with the distance to the nearest neighbor of the formate species estimated to be 5.0 ± 0.2 A, twice that of the nearest Cu−Cu neighbor. The adsorption phase of formate thus grows linearly at the initial stage by an anisotropic attractive interaction between the formate species. The ordered structure of the formate species changed in the order of p(2 × 4), c(2 × 8), (7 × 7), p(2 × 3), (5 × 5), and c(2 × 4) with increasing formate coverage, indicating that various ordered structures appeared corresponding to the small change in the formate coverage. All the formate structures, except for (7 × 7) and ...

The kinetics of both the formate synthesis of hydrogenation of CO2 and the formate decomposition has been studied on clean Cu(111) and Cu(110) surfaces using in situ infrared reflection absorption spectroscopy. It has been found that the formate synthesis does not depend on the surface structure of copper between Cu(111) and Cu(110). The activation energies for the initial formation rate of formate species on Cu(111) and Cu(110) have been determined to be 56.6±4.8 and 59.8±4.1 kJ mol−1, respectively. On the other hand, the activation energy and the pre-exponential factor for the formate decomposition on Cu(111) are widely different from those on Cu(110), indicating that the decomposition of the formate species depends on the Cu surface structure. The position of the neighboring Cu atom is considered to be important for the kinetics of the decomposition since the transition state of the formate decomposition may pass through by the OCO plane vibration toward the surface.

Formate species synthesized by the hydrogenation of CO 2 over clean Cu(111) and Zn-deposited Cu(111) surfaces at atmospheric pressure were studied by in-situ infrared reflection absorption spectroscopy (IRAS). The symmetric OCO stretching (v s (OCO)) peak of a bidentate formate species on clean copper was observed at ∼ 1330 cm -1 on both surfaces during the reaction. The initial formation rate of formate species on the clean Cu(111) surface at 353 K and 760 Torr was estimated to be 8.2 x 10 -4 (molecules site -1 s - 1 ). which agreed with results previously obtained by XPS. In contrast, peaks at 1350 and 1585 cm -1 were observed during the hydrogenation of CO 2 only on the Zn-deposited Cu(111) surface. The peak at 1585 cm -1 agreed with the frequency of the asymmetric OCO stretching (v a (OCO)) of bridging bidentate formate species, thus indicating that an inclined formate species was adsorbed on two different atoms of the Cu-Zn site previously proposed as the active site of methanol synthesis.

The catalytic activity of Zn vapor-deposited Cu(100) and Cu(110) surfaces for methanol synthesis by the hydrogenation of CO2 and the reverse water-gas shift reaction were studied using an XPS apparatus combined with a high-pressure flow reactor (18 atm). At a reaction temperature of 523 K, no promotional effect of Zn was observed for the methanol synthesis on both Zn/Cu(100) and Zn/Cu(110). The results were quite different from those for Zn/Cu(111), on which a significant promotion of methanol synthesis activity appeared to be due to the deposition of Zn, indicating that the promotional effect of Zn was sensitive to the surface structure of Cu. However, hysteresis was observed in the catalytic activity for methanol synthesis over the Zn/Cu(110) surface upon heating above 543 K in the reaction mixture. The activity became twice that measured before heating, which was close to the methanol synthesis activity of Zn/Cu(111) at the same Zn coverage. On the other hand, no such hysteresis was observed for the reverse water-gas shift reaction on Zn/Cu(110), indicating that the active site for methanol synthesis was not identical to that for the reverse water-gas shift reaction. In the post-reaction surface analysis, formate species was detected on both Zn/Cu(100) and Zn/Cu(110), whose coverage increased with increasing Zn coverage at 0

The role of Zn in the promotion of methanol synthesis over Cu surfaces was studied by elucidating effects of Zn on both synthesis and decomposition of formate species using XPS. The initial formation rate of formate over Zn-free Cu(111) was measured to be 7.6 X 10 -4 molecules site -1 s -1 at P H2 = P co2 = 380 Torr and 353 K. The rate of formate synthesis over Zn-deposited Cu(111) was the same as that on Zn-free Cu(111), indicating that formate species were synthesized on copper surfaces and Zn had no promotional effect on the formate synthesis. On the other hand, the surface formate species on Zn-deposited Cu(111) decomposed at a temperature higher than that on Zn-free Cu(111) by ∼ 50 K, suggesting that Zn deposited on Cu(111) created special sites stabilizing formate species. These results suggested that the role of Zn on methanol synthesis by the hydrogenation of CO 2 is to stabilize the formate intermediate, and to promote a hydrogenation process of formate species.

Strontium and Nd isotopic compositions and trace element abundances were determined for Cretaceous to late Cenozoic igneous rocks from the Japan Sea side of Southwest Japan in order to investigate the effect of the opening of the Japan Sea on igneous activity. The 87Sr/86Sr ratios for both high and low silica rocks decrease with decreasing age since the middle Miocene, when the opening occurred. Similarly, 143Nd/144Nd values for these rocks increase with decreasing age, and are negatively correlated with 87Sr/86Sr ratios. A two-component mixing process can best account for these isotopic and chemical characteristics. One end-member is likely the subcontinental lithospheric mantle (SCLM) and its derivative mafic to intermediate materials which had ɛNd values of around +3. The other endmember consists of mafic to intermediate rocks with low ɛNd values (e.g., −8), probably located in the lower crust. The mantle upwelling associated with the opening of the Japan Sea did not supply typical MORB or MORB-source materials to the crust, but did provide the heat that caused the melting of lithospheric mantle and lower crust.

The synthesis of formate species on Cu(111) surfaces by hydrogenation of CO2 at atmospheric pressure was studied by x-ray photoelectron spectroscopy and scanning tunnel microscope (STM). The initial formation rate of formate was measured to be 2.1×10−4 molecules site−1 s−1 at PH2=PCO2=380 Torr and 333 K. The saturation coverage of formate species was estimated to be ΘHCOO=0.24, where Θ=1 corresponded to the number of Cu surface atoms. No promotional effect of Zn on the formation of formate species over a Cu(111) surface was observed, indicating that the promotional effect of Zn previously observed for methanol synthesis on Cu(111), is not ascribed to promotion in the formate formation, but is ascribed to promotion in a hydrogenation process of formate species. STM images were obtained for individual formate species synthesized on a clean Cu(111) surface by hydrogenation of CO2 at PH2=PCO2=380 Torr and 333 K for 20 min. Formate species arranged in a hexagonal structure with a distance of 6.6±0.2 A were att...

The effect of ZnO/SiO2 in a physical mixture of Cu/SiO2 and ZnO/SiO2 on methanol synthesis from CO2 and H2 was studied to clarify the role of ZnO in Cu/ZnO-based catalysts. An active Cu/SiO2 was prepared by the following procedure: the Cu/SiO2 and ZnO/SiO2 catalysts with a different SiO2 particle size were mixed and reduced with H2 at 523-723 K, and the Cu/SiO2 was then separated from the mixture using a sieve. The methanol synthesis activity of the Cu/SiO2 catalyst increased with the reduction temperature and was in fairly good agreement with that previously obtained for the physical mixture of Cu/SiO2 and ZnO/SiO2. These results indicated that the active site for methanol synthesis was created on the Cu/SiO2 upon reduction of the physical mixture with H2. It was also found that ZnO itself had no promotional effect on the methanol synthesis activity except for the role of ZnO to create the active site. The active site created on the Cu/SiO2 catalyst was found not to promote the formation of formate from CO2 and H2 on the Cu surface based on in situ FT-IR measurements. A special formate species unstable at 523 K with an OCO asymmetric peak at ~1585 cm-1 was considered to be adsorbed on the active site.

The synthesis of methanol by the hydrogenation of CO2 over Zn‐deposited and Zn‐free single‐crystal copper surfaces has been studied using an x‐ray photoelectron spectroscopy apparatus combined with a high‐pressure flow reactor (18 atm). The order of plane for the catalytic activity was (110)≳(311)≳(100)≳(111) for Zn‐free copper surfaces. The Zn‐deposited Cu(111) (ΘZn=0.19) was 13 fold more active than the Zn‐free Cu(111). The activation energy for the methanol synthesis (73–84 kJ/mol) was close to each other regardless of the surface structure or the presence of Zn. It was shown that the Zn deposited on Cu(111) acted as a promoter for the methanol synthesis, while the Zn on Cu(110) and Cu(100) had no such a promotional effect. On the postreaction surfaces of Zn‐deposited and Zn‐free copper samples, a small amount of formate species was always detected which was more stable than that on clean Cu surfaces. This formate species’s coverage was proportional to the activity for methanol formation.

The hydrogenation of CO2over a Zn-deposited polycrystalline Cu surface was performed at 523 K and 18 atm using a high-pressure reactor combined with an XPS–AES apparatus. It was clearly shown that ZnOxspecies formed on the Cu surface during the reaction directly promoted the methanol formation activity, indicating the creation of active sites except for Cu0. At optimum Zn coverage (ΘZn = 0.17) the Zn-deposited Cu surface was sixfold more active than the Zn-free Cu surface for methanol formation. The turnover frequencies (TOF) increased with Zn coverage below ΘZn = 0.17 and decreased above ΘZn = 0.17. The TOF and the activation energy for methanol formation over the Zn-deposited Cu were in fairly good agreement with those for the Cu/ZnO powder catalysts. Thus, the Zn-deposited Cu surface can be regarded as a model of Cu/ZnO catalysts. The postreaction surface analysis by XPS, after evacuation of the reaction mixture at 523 K, showed the formation of ZnOxspecies with a Zn/O ratio of about unity at any Zn coverage. Formate species was observed on the postreaction Cu surface in the presence of the ZnOxspecies. The amount of the formate species increased with ΘZnbelow ΘZn = 0.2 and then slightly decreased at ΘZn > 0.2.

Abundances of REEs and other trace elements were determined for granitic rocks and their mineral separates from the Sanin, Sanyo, and Ryoke belts in the Inner Zone of southwest Japan. Among those data obtained, the Fe and Co partition coefficients between plagioclase and biotite were found to be specially important. The partition coefficients for Fe are negatively correlated with those for Co, and values for the magnetite-series granites from Sanin belt are clearly separated from those for the ilmenite-series granites of Ryoke belt. The Sanyo belt samples, which include both types of granites, fall within the range of the Ryoke ilmenite-series granites. The variation of Fe and Co partition coefficients can be interpreted by the difference in redox states, crystal chemistry of these minerals, and kinetic disequilibrium effect. The Sanyo belt data suggest that the ilmenite-series granites were converted from a magma with magnetite-series affinity during later solidification stages. Moreover, the Eu2+/Eu3+ ratios in minerals were calculated by the Philpotts' method in which the equivalence of Eu2+ and Sr2+ partitioning is assumed. The Eu2+/Eu3+ ratio in plagioclase from the Sanyo and Ryoke belt granites seems to be correlated with the whole-rock Fe2+/Fe3+, though the Sanin belt granites tend to show high plagioclase Eu2+/Eu3+ ratios probably due to a disequilibration caused by rapid solidification. Furthermore, effect of redox states on the size of the Eu anomaly in plagioclase/melt partition coefficient was examined from the plagioclase Eu2+/Eu3+ data of the granites.

The hydrogenation of CO2 over Zn-deposited Cu(111) and Cu(110) surfaces was performed at 523 K and 18 atm using a high pressure flow reactor combined with XPS apparatus. It was shown that the ZnO x species formed on Cu(111) during reaction directly promoted the methanol synthesis. However, no such promotional effect of the Zn was observed for methanol formation on Cu(110). Thus, Zn on Cu(111) acts as a promoter, while Zn on Cu(110) acts as a poison. The activation energy and the turnover frequency are in fairly good agreement with those obtained for Cu/ZnO powder catalysts.

Methanol synthesis by the hydrogenation of CO2 over Zn-deposited polycrystalline Cu was studied using surface science techniques. The Zn sub-monolayer was oxidized by the reaction mixture during the reaction at 523 K, leading to the formation of ZnO species. The kinetic results definitely showed that the ZnO species on the Cu surface promoted the catalytic activity of methanol formation, where the activity of Cu increased by a factor of 6 at the Zn coverage of 0.17. A volcano-shaped curve was obtained for the correlation between the Zn coverage and the catalytic activity, which was very similar to the correlation curve between the oxygen coverage and the specific activity for methanol formation previously obtained for the Cu powder catalysts. The role of ZnO in Cu/ZnO based catalysts was ascribed to the stabilization of Cu+ species by the ZnO moieties on the Cu surface.

The behaviour of the rare-earth elements (REE), Sc and Ba during rhyolite-hydrothermal water interactions has been investigated experimentally. Both leaching and sorption experiments were performed using various solutions (i.e., pure water, dilute HCl solution, the solution doped with REE, Sc and Ba). Most runs were at 250°C and 1 kbar. The mobility of these elements in our hydrothermal reactions was found to be dependent on the concentration of HCl (or pH) in the solution. In near-neutral solutions, REE showed considerable mobility but no relative fractionation, whereas fractionation did occur between REE and Sc. In dilute HCl solution REE behaviour is quite complex: in sorption experiments, REE remained in 2 N HCl solution, whereas in 0.1–0.6 N HCl solutions REE were readily incorporated into the solid. In contrast, Ba showed strong affinity for the dilute HCl solution. A large fractionation between light and heavy REE was observed in an intermediate case between high and low HCl concentrations. The mechanisms of these trace-element behaviours are not clearly understood, but ion exchange properties of a thin surface layer may be important.

The synthesis of methanol by the hydrogenation of C02 over Zn-deposited and Zn-free copper surfaces has been studied using an XPS apparatus combined with a high-pressure flow reactor (18 atm). It was shown that the Zn deposited on Cu(111) and poly-Cu acted as a promoter for methanol synthesis, while the Zn on Cu(110) and Cu(100) had no such a promotional effect. The turnover frequency (TOF) for Zn/Cu(111) linearly increased with Zn coverage below ΘZn=0.19, and then decreased above ΘZn=0.20. The optimum TOF obtained at ΘZn=0.19 was thirteen-fold lager than TOF for the Zn-free Cu(111) surface. On the other hand, no promotional effect of Zn was observed for the reverse water-gas shift reaction on all the surfaces. The results indicate the formation of special sites for methanol synthesis on Zn/Cu(111). The Zn-deposited Cu(111) can be regarded as a model of Cu/ZnO catalysts because the TOF and the activation energy for methanol formation over the Zn-deposited 0(111) were in fairly good agreement with those for the Cu/ZnO powder catalysts. The post-reaction surface analysis by XPS showed the formation of formate species (HCOOa). The formate coverage was proportional to the activity for methanol formation below ΘZn=0.20, suggesting that the hydrogenation of the formate species is the rate-determing step of methanol formation. The formate species was stabilized by Zn species on Cu(111) in the absence of ZnO species. STM results on the Zn-deposited Cu(111) suggested the formation of a Cu-Zn surface alloy. The presence of special sites for methanol synthesis was also indicated in the results of powder catalysts.

A pre-irradiation group separation method has been developed for the neutron activation analysis of rare earth elements (REE) and Ba in silicate rocks. REE and Ba were quantitatively separated from other elements by cation exchange column method. The chemical yield of each separation was monitored with Pr added to the sample powder before decomposition. The accuracy and precision were tested by repeated analyses of JB-1 and one analysis of BCR-1. In addition, it was found that REE distribution in a granitic rock powder was inhomogeneous and therefore special care must be taken for the sampling of granitic rock powders.

A 3.3 l liquid hydrogen and deuterium target cell of diameter 140 mm and length 230 mm constructed from 0.2 mm-thick stainless-steel sheet was used for an experiment on the annihilation of antiprotons at rest in the KEK 12 GeV Proton Synchrotron. The target cell was mounted deep inside the detector system, and the whole target system was designed for safety in case of breakage of the target cell, because the detector was contained in an enclosed room. The liquid level in the cell could be monitored well with carbon resistors distributed on its outer surface.