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The reaction of Al and H2O is a promising method for the renewable production of H2 (an environmentally friendly fuel whose combustion produces only water), because it does not directly include fossil fuels conversion. This reaction was studied at extreme pH values as low as 1 and as high as 13.5 with HCl, H2SO4, and NaOH, and at low hydrothermal temperatures of 40-100 °C. Factors such as pH, temperature, and solution medium influenced H2 production, which was considerably greater at higher temperatures and more extreme pH (acidic or alkaline). Alkaline conditions consistently favored more rapid H2 production than acidic conditions. Under the most extreme conditions, the activation energy was ∼60 kJ mol−1 for both acidic and alkaline reactions. A model predicting H2 production in acidic reactions was derived from the reaction mechanism and kinetics. The model yielded a good fit to on-site measurements at the Tamagawa and Zao hot springs in northeast Japan. This study would aid the development of industrial H2 production systems using natural acidic hot springs or alkaline industrial wastewater.

Hydrogen is gaining attention as an energy source, but its production through fossil-fuel use is not environmentally friendly. A more sustainable source could be the hydrothermal reaction involving aluminum and water reaction, which owns technical issues on aluminum passivation and material sources for the upscale application. This study analyzes the aluminum-water hydrothermal reaction at laboratory and field scales and includes an environmental assessment of H2 fuel production involving hot-spring water with extremely low pH (~1) and boiling temperature (~373 K). Acidic hot-spring alternates water sources, and its unique feature activates aluminum surface by attacking oxide layer, hence enables H2 generation. Aluminum waste sources include dross and cutting chips, which could replace primary aluminum metal. The highest H2 yield could be obtained of about ~55 mmol H2 gAl−1 for the chip (almost reached theoretical yield) and a smaller amount of ~20 mmol H2 gAl−1 for dross. The environmental assessment comprises carbon dioxide emissions and energy consumption from the overall H2 fuel system resulting in a reduced environmental impact. The proposed hydrogen production method encourages hydrogen energy development from the local scale. In addition, the use of aluminum waste materials is a new and useful waste management strategy than direct disposal, and hot-springs use advances its direct utilization.

Spectroscopic characteristics of critical phenomena of multicomponent geofluids and seawater were observed by using autoclave with transparent windows (visible-type autoclave). First, pure H2O fluids were observed by spectroscopic measurements at 500–800nm under high temperature and pressure conditions. The intensity of light transmitted decreased significantly as the critical point of H2O fluid was approached, and the local minimum intensity of transmitted light corresponded to the critical temperature and pressure of all fluids tested. The experimentally determined critical temperature and pressure of H2O were similar to the results of previous work. Critical temperatures and pressures of multicomponent geofluids and seawaters were determined. Spectroscopic measurement could provide information of molecular behaviours of aqueous fluid involving several kinds of electrolytes.

Serpentinization occurs via interactions between mantle peridotite and water that commonly passes through the crust. Given that such a fluid has a high silica activity compared with mantle peridotite, it is thought that serpentinization and silica metasomatism occur simultaneously at the crust–mantle boundary. In this study, we conducted hydrothermal experiments in the olivine (Ol)–quartz (Qtz)–H 2 O system at 250 °C and vapor-saturated pressure under highly alkaline conditions (NaOH aq , pH = 13.8 at 25 °C) to clarify the mechanism of silica metasomatism at the crust–mantle boundary. Composite powders consisting of a Qtz layer and an Ol layer were set in tube-in-tube vessels. After the experiments, the extents of serpentinization and metasomatic reactions were evaluated as a function of distance from the Ol–Qtz boundary. The mineralogy of the reaction products in the Ol-hosted region changed with increasing distance from the Ol–Qtz boundary, from smectite + serpentine (Smc zone) to serpentine + brucite + magnetite (Brc zone). Olivine hydration proceeded in both zones, but the total H 2 O content in the products was greater in the Brc zone than in the Smc zone. Mass balance calculations revealed that olivine hydration occurred without any supply of silica in the brucite zone. In contrast, the Smc zone was formed by silica metasomatism via competitive hydration and dehydration reactions. In the Smc zone, smectite formed via the simultaneous progress of olivine hydration and serpentine dehydration, and around the boundary of the Smc and Brc zones, serpentine formation occurred by olivine hydration and brucite dehydration. The relative extent of hydration and dehydration reactions controlled the along-tube variation in the rate of H 2 O production/consumption and the rate of volume increase. Our findings suggest that the competitive progress of serpentinization and silica metasomatic reactions would cause fluctuations in pore fluid pressure, possibly affecting the mechanical behavior of the crust–mantle boundary.

Silica activity is one of the key factors in controlling reaction paths of serpentinization. We conducted hydrothermal experiments in the olivine (Ol)–orthopyroxene (Opx)–H 2 O system at 250 °C and at a vapor-saturated pressure of 3.98 MPa to explore the role of silica diffusion in aqueous fluids during serpentinization. Olivine (Fo 91 ), orthopyroxene (En 91 ), or their composite powders (with Ol/Opx/Ol zones) were set in tube-in-tube vessels, and solution chemistry and the extent of serpentinization were analyzed in detail. In the Ol–H 2 O experiments, the product changed from serpentine + magnetite to serpentine + brucite + magnetite, accompanied by a Si-drop in the solutions. Serpentinization proceeded uniformly throughout the reaction tube, indicating that the supply of water was not the rate-determining process. In the Opx–H 2 O experiments, orthopyroxenes were dissolved along the cleavages, and the amount of newly formed serpentine was very small. The silica activity of the solutions in the Opx–H 2 O experiments was 1–3 orders higher than in the Ol–H 2 O experiments. In the Ol–Opx–H 2 O experiments, serpentinization proceeded in both the Ol and Opx zones. In the Opx zone, the extent of serpentinization was constant, whereas in the Ol zone, serpentinization was most extensive along the boundary between the Ol and Opx zones, and it decreased gradually away from the boundary. Serpentinization in the Ol–Opx–H 2 O experiments was modeled simply by coupled processes involving silica diffusion and two serpentinization reactions: a silica-consuming reaction after olivine and a silica-releasing reaction after orthopyroxene. The spatial pattern of the extent of serpentinization was controlled by the diffusion coefficient of silica in aqueous solution, D SiO2,aq , and the apparent reaction rate constants k ′ Ol in the olivine zone, and k ′ Opx in the orthopyroxene zone. Assuming D SiO2,aq = 2.0 × 10 −4 cm 2 /s, the observed variation in the extent of serpentinization after a run of 1512 h is best fitted by simulation with k ′ Ol = 4.4 × 10 −4 and k ′ Opx = 3.2 × 10 −5 s −1 , indicating a reaction rate constant ∼14 times higher in the Ol zone than in the Opx zone. Our experimental results represent an analogue of serpentinization in natural hydrothermal systems with a high porosity, and we suggest that the spatial variation of serpentine as a function of the distance from a source of silica could be a useful indicator of the relative magnitudes of reaction, mass transport, fluid flow as well as temperature during hydrothermal alteration of oceanic lithosphere.

Silica activity plays an important role in controlling reaction paths and rates of serpentinization in the oceanic lithosphere. In this study, we conducted hydrothermal experiments on serpentinization in the olivine (Ol)- orthopyroxene (Opx)-H2O system at 250 °C and vapor-saturated pressure (3.98 MPa). We used a tube-in-tube vessel with powders of Ol/Opx/Ol zones, and the extents of serpentinization and solution chemistry were analyzed in detail. The run time was up to 1512 hours. The silica activity of the solutions decreased with time from 0.144 to 0.005 mmol/kg, whereas the Mg concentration and pH were nearly constant. The experimental products were serpentine (mainly lizardite) ± magnetite, and neither talc nor brucite was found. The extent of serpentinization, measured by thermogravimetry and SEM-images, revealed that serpentinization was most extensive along the boundary between the Ol and Opx zones, and decreased gradually away from the boundary. This extent of serpentinization pattern is explained by the coupled processes of silica diffusion and surface reactions in both zones (silica-consuming reaction in the Ol zone and silica- releasing reaction in the Opx zone).

Hydrogen production from water with S2− as a reductant under hydrothermal conditions is an effective new method, in which S2− is oxidized into S2O32−, SO32− and SO42−. However, the reactor wall had great effect on hydrogen production as large amount hydrogen is produced with Hastelloy C-22 reactor while almost no hydrogen generated in SUS 316 reactor. Therefore, the influence of main components of Hastelloy C-22 reactor (Co/W/Ni) and SUS 316 reactor (Fe) on hydrogen production with H2S as the reductant was investigated. The results showed that Fe had negative effect, whereas W, Co and Ni had significant positive effect on improving hydrogen production. These results provided a possible explanation for no hydrogen generated with SUS 316 reactor，and some suggestions for improving hydrogen production. The highest hydrogen production of 199 mL (2 times than the control) was obtained with 4.00 mmol Co, 4.00 mmol W, and 1.00 mmol Ni.

High temperature-pressure cell for micro-IR and Raman spectroscopy have been developed to investigate molecular structure of water under sub- and supercritical conditions. The maximum temperature and pressure of the cell were 400 °C and 50 MPa, and artificial yellow diamond was installed as a transparent window of the cell. In case of micro-IR spectroscopic measurement, incident beam was illuminated to the high temperature-pressure cell using the Cassegrainian mirror, and reflected light was analyzed by FTIR system. In case of micro-Raman spectroscopic measurement, an incident laser beam (Nd:YAG laser: 532 nm) was irradiated into the cell through standard optical lens. As a result of infrared spectroscopic measurements of water, the broad peak around 3360 cm-1 of infrared spectra, attributed to OH stretching vibration mode of water molecular, was observed at room temperature and pressure. The peak position shifted to higher wavenumber with increasing temperature and shifted to lower wavenumber with increasing pressure. Continuous shift of the OH stretching vibration mode of water molecule was detected by using newly designed high temperature-pressure cell. The peak position and behavior of peak shift of interfacial water were affected by substrate. In case of interfacial water on artificial quartz, the peak position shifted to higher wavenumber with increasing temperature, however no obvious change was observed with as a function of pressure. It was possible to measure IR and Raman spectra under supercritical condition by using high temperature-pressure cell, and characteristics of molecular structure of interfacial water revealed by IR spectra was changed by environmental conditions such as temperature, pressure and substrate.

Li-bearing tosudite has a regularly interstratified structure consisting of chlorite and smectite layers. Hydrothermal treatment of unground and ground Li-tosudite was carried out under 150°C to 250°C in a distilled water and various concentrations of NaOH solutions, and the reacted products were examined by XRD, ethylene gricol treatment and methylene blue absorption capacity.The final reacted products obtained from the both of unground and ground Li-tosudite were mainly analcime, and swelled Li-tosudite was also formed as a by-product. The formation temperature of analcime using ground Li-tosudite was low compared with that using unground Li-tosudite, and its temperature was also related to concentration of NaOH solution. The analcime formation temperature become low with increasing NaOH concentration in the both cases of unground and ground Li-tosudite.Heterogeneous substitution of interlayer cation (Na+) was considered to be occurred on the basis of different features of XRD profile after ethylene gricol treatment and under various relative humidity states.The interlayer structure of Li-tosudite was altered into complex interlayer structure of swelled Li-tosudite, and analcime was readily obtained as a final product from the unground Li-tosudite compared with the ground Li-tosudite. These facts suggest that the reacted products of hydrothermal treatment reflect an original crystal structure of the starting material.

There have been several reports that photodesorption due to synchroton radiation from OFC copper chambers with machined surfaces is far lower than in stainless steel or aluminum alloy chambers. However, it is difficult to process machined surfaces for the inner surfaces of beam chambers. A surface treatment using broaching has been developed to cut the inner surface of the chamber. Tests of the photodesorption caused by synchrotron radiation in a small, broached, cylindrical cross-section chamber with a length of 30 cm have been reported. To adapt the broaching method to long chambers, prototype copper vacuum chambers with lengths of 1.8 m and 2 m have been fabricated. A chamber consists of a beam channel, a cooling channel, and a NEG pump channel. The beam channel, which has a hexagonal cross section, is broached. An ultimate pressure of 1 × 10 −8 Pa was obtained after bakeout at 200 °C for 24 h and NEG activation.

A new method for surface treatment of copper vacuum chamber has been developed to easily obtain lower photodesorption coefficients due to synchrotron radiation at low cost. An oxygen‐free high‐conductivity (OFHC) copper test chamber is extruded and degreased, then the inner surface is cut by broaching. The length of the test chamber is 300 mm and the outer diameter is 65 mm. For comparison, three OFHC copper test chambers are manufactured with different surface treatments. These treatments are (1) acid cleaning (pickling in a mixed solution of HNO3 and H2SO4, followed by passivation in a chromic acid with H2SO4), (2) broaching with oil, and (3) oil‐free broaching. These test chambers were exposed to synchrotron radiation with 4 keV critical energy from BL21 beamline at the Photon Factory 2.5 GeV storage ring at KEK. The photodesorption coefficients (N2 or CO equivalent) for the chamber treated with oil‐free broaching and for the chamber treated with acid cleaning are almost the same. However the decreasin...

Variations of topographic and current images with bias voltages were examined utilizing the current imaging tunneling spectroscopy (CITS) and dual‐polarity tunneling imaging (DPTI) techniques. While the CITS and DPTI images of the Si(111)‐(7×7) reconstructed structure at the specimen voltage of +2 V and the DPTI image at −2 V are reliably reproducible exhibiting bright Si adatoms and dark corner holes, the CITS current image at −2 V often showed reversed contrast grey‐scale images with bright corner holes. The observed reversed image is explained as the result of the difference in the effective tunneling barrier and the surface state density of the tip apex and specimen, and also as the effect of the atomic arrangement and composition and profile of the tip apex.

Si(111) surfaces heated at 1300 °C show many steps and terraces exhibiting the (√3×√3) R 30°, c(4×2), (5×5), (7×7), and (9×9) reconstructed structures. A detailed study of the surface corrugation indicates that the observed maximum depth of the corner hole is 2.4 A and the trace of a scanning tip is close to the profile of the [111]‐oriented W tip with a single atom at the apex and the most desirable cone angle of ∼120°. Occasionally, anomalous, ordered structures appeared and were explained as the result of the scanning with two apex atoms 4.5 A apart, the distance between the nearest surface atoms of the W(111) plane.

In order to investigate effects of molecular behavior of water at interface on the rock surface, high temperature‐pressure cell (up to 400 °C and 50 MPa) was developed to measure infrared and Raman, which was attached with optical microscopy, therefore, in situ and microscopic measurements were enable at high temperature and pressure conditions. Infrared properties of thin film water and interfacial water at rock surface were measured. As a result of infrared spectroscopic measurements of thin film water, the broad peak at ca. 3360 cm−1 of infrared spectra, attributed to OH stretching mode of water molecular, was observed at room temperature and pressure. Continuous shift of the OH vibration mode was obtained from room to hydrothermal conditions. These results indicate that changes of molecular structure of the water were detected by using newly designed high temperature‐pressure cell. Compared with the result of infrared properties of thin film water, infrared properties of interfacial water at rock surface exhibit different trend: the peak position shifted to higher wavenumber with increasing temperature and did not shift with pressure. Molecular structure of interfacial water on the rock and rock‐forming mineral at elevated temperatures and pressures were not only changes due to physical conditions such as temperature and pressure but also interaction between interfacial water and solid rock materials.

1,4-Cyclohexadiene was hydrogenated selectively to cyclohexene with a nickel catalyst generated from bis(acetylacetonato)nickel(II), triethyldialuminium trichloride, and triphenylphosphine at 40 °C under an atmospheric pressure of hydrogen. The hydrogenation of eleven kinds of alkyl-substituted 1,4-cyclohexadienes gave the corresponding cyclohexenes in good yields by the nickel catalyst. The structural factors of the alkyl substituent on the diolefin are shown to affect the hydrogenation rate. The homogeneous nickel catalyst system, in which a nickel hydride complex NiH(PPh3)(AlCl4) is supposed to be an active species, was effective for the selective hydrogenation of the diolefin to the olefin. A plausible pathway involving π-allylnickel complexes for the hydrogenation is proposed.

Spectroscopic measurements in the range from 350 nm to 1050 nm for pure H 2 O and CO 2 fluids at high temperatures and pressures were carried out to observe critical phenomena using an optical cell autoclave. The intensity of transmitted light though the fluid became drastically lower around the critical point in both cases of H 2 O. The minimum intensity of transmitted light corresponded to the critical temperature and pressure of each fluid. The supercritical region beyond the critical point for water has been inferred to be a homogeneous state, which does not correspond to either a true liquid phase or a true vapor phase. Results of supercritical-state dissolution experiments using granite and quartz show that this fluid can be subdivided into two apparent phases comprising a ‘liquid-like’ region and a ‘vapor-like’ region. Spectroscopic measurements are powerful tool to identify bulk molecular behavior of fluids at sub-and supercritical states.