Analysis of Lignin Aromatic Structure in Wood Fractions Based on IR Spectroscopy

In our previous studies, a method of quantitative analysis of lignin structure by IR spectroscopy with direct use of wood meal was developed which can be apply to a wide range of wood species. Lignin structure deposition in different fractions in the same wood sample also has characteristic diversity and differences. In this study, quantitative analysis of lignin structure by IR spectroscopy was used to determine whether it can be applied to different fractions in the same wood sample. Finely milled beech wood was fractionated by stepwise extraction using aqueous dioxane and followed by subsequent dimethyl sulfoxide (DMSO)/LiCl solvents with increasing LiCl concentrations. The results showed that fractions of the peak area ratio of log(1595/1509) fit a linear relationship with different wood species very well. Therefore, log(1595/1509) could be used not only with different wood species but also with different fractions from the same wood. For 1509/1460, log(1275/1220), 1130/1030 and 835/(835+815), different fractions deviated from the original relationship obtained from different wood species.     

Synthesis of polysiloxane-modified silica hybrid particles by a high temperature water technology

Polysiloxane-modified silica hybrid particles were synthesized by hydrolysis and subsequent polycondensation of phenyltrimethoxysilane in the presence of colloidal silica at above 220 °C. The process variables include pH of the colloid, [silica]/[phenyltrimethoxysilane] molar ratio, reaction temperature, and reaction time. The products were characterized by solvent extraction, TGA, GPC, TEM, and ²⁹Si NMR. The degree of surface modification (DOM) ranged between 5 and 35 wt.% by tuning the process variables when a neutral colloid was used. On the other hand, the DOM proved to be strongly dependent on temperature and becomes essentially zero when the synthesis was conducted with an acidic colloid at temperatures as high as 350 °C. TEM analysis suggested that each silica particle was surface modified resulting in minimal aggregation of the particles. The hybridization mechanism was studied by the DOM and the molecular weight of ungrafted polysiloxane.     

External mass transfer in silica monolithic stationary phases

A detailed analysis of a procedure of measurement of the external mass transfer coefficients (k_f) in RPLC systems is provided. Application is described for a system consisting of a C₁₈-silica monolithic column and a methanol/water eluent (70/30, v/v). The k_f values of butylbenzene at 298 K were derived from peak profiles recorded in pulse response experiments by subtracting the contributions of the kinetic processes, i.e., axial molecular diffusion, eddy diffusion, pore and surface diffusion, from the band variance. This approach provided the Sherwood number (Sh) for a range of Reynolds number (Re) between 0.002 and 0.005 and a Schmidt number (Sc) equal to 2.7×10³. The experimental values of k_f were compared with those estimated from literature correlations, giving a relative error of ca. 11% when Pfeffer equation was used for estimating k_f. The exponents obtained for Re and Sc in Sh were 0.43 and 0.39, values comparable with those found in literature correlations, i.e., 0.33. The k_f values estimated using the reference correlations are of the same order of magnitude as the experimental k_f values. The acquisition of more experimental data is needed for deriving an improved correlation affording more accurate estimates of k_f in stationary phases of cylindrical shape, like silica monoliths.     

Energy-Efficient Low Rank Coal Drying Based on Enhanced Vapor Recompression Technology

Vapor recompression is considered a highly energy-efficient technology to recover the heat involved in a process. Unfortunately, in conventional vapor recompression technology, not all of the heat can be recovered effectively. In this study, an enhanced vapor recompression technology enabling more effective heat recovery is proposed, and its ability to dry low rank coal (LRC) is evaluated. We consider the factors of exergy recovery and heat coupling. In addition to conventional vapor recompression, enhanced vapor recompression technology used to dry LRC can recover effectively the sensible heat of dried solid LRC through water recirculation. Moreover, we show that there is an optimum amount of recirculated water for each initial and target moisture content. A temperature–enthalpy diagram reveals that the proposed enhanced vapor recompression technology shows effective heat coupling for each type of heat, which results in less exergy loss so that a marked reduction in energy consumption can be achieved.     

Activity of oxygen reduction reaction on small amount of amorphous CeOx promoted Pt cathode for fuel cell application

Pt on ceria (CeO_x) particles supported on carbon black (CB) were synthesized using the combined process of hot precipitation and impregnation methods. During 30 cycles of cyclic voltammetry pre-treatment in the potential ranging from −0.2 to 1.3 V (V vs. Ag/AgCl), it was observed that a small amount of CeO_x, which consisted of the interface region between Pt and CeO_x, remained on Pt particles. Other free CeO_x particles were dissolved into H₂SO₄ aqueous solution. To develop the Pt-CeO_x/CB catalyst, the surface chemical states, the net chemical composition, morphology and electrochemical behavior in H₂SO₄ aqueous solution were characterized. Our microanalysis and electrochemical analysis indicate that the active CeO₂ with high specific surface area provides the continuous amorphous cerium oxide (Ce³⁺, Ce⁴⁺) layer with pores on the surface of Pt particles. It is concluded that the amorphous cerium oxide layer on Pt inhibits the oxidation of Pt surface and contributes to enhancement of the activity on Pt cathode. The single cell performance was also improved using the Pt-CeO_x/CB cathode. Based on all data, it is expected that the design based on characterization of the interface between Pt and small amount of amorphous cerium oxide layer could help in preparation of more active Pt catalyst.     

Benchmarking of activation reaction distribution in an intermediate energy neutron field

Neutron-induced reaction rate depth profiles inside concrete shield irradiated by intermediate energy neutron were calculated using a Monte-Carlo code and compared with an experiment. An irradiation field of intermediate neutron produced in the forward direction from a thick (stopping length) target bombarded by 400 MeV nucleon(-1) carbon ions was arranged at the heavy ion medical accelerator in Chiba. Ordinary concrete shield of 90 cm thickness was installed 50 cm downstream the iron target. Activation detectors of aluminum, gold and gold covered with cadmium were inserted at various depths. Irradiated samples were extracted after exposure and gamma-ray spectrometry was performed for each sample. Comparison of experimental and calculated shows good agreement for both low- and high-energy neutron-induced reaction except for (27)Al(n,X)(24)Na reaction at the surface.     

Study on paper-structured catalyst for direct internal reforming SOFC fueled by the mixture of CH4 and CO2

Inorganic fiber network including YSZ fiber which acts as catalyst support was created by the simple paper-making process, and novel Ni-loaded paper-structured catalysts (PSCs) with excellent catalytic activity for the dry reforming of methane were designed and developed. The PSCs exhibited high fuel conversion comparable to the conventional powdered catalysts with less than one-tenth catalyst weights. The significant advantages of the PSCs are their high mechanical flexibility and material workability. So far, a functionally-graded catalytic reaction field which leads to uniform temperature distribution during biogas reforming resulting in stable operation of planar SOFC was successfully developed by the PSC array based on the kinetic simulation model built in this research.     

On-Paper Synthesis of Nickel Nanoparticles and Catalytic Propane Steam Reforming for Efficient Hydrogen Production

Nickel nanoparticles (NiNPs) were successfully synthesized in situ on a microstructured paper matrix composed of inorganic fibers as the main framework and zinc oxide (ZnO) whiskers as a preferential support for NiNPs. The paper-like inorganic fiber/ZnO whisker composites were prepared using a high-speed and low-cost papermaking technique, and then simply immersed in an aqueous solution of Ni(NO₃)₂. After reduction in hydrogen flow, NiNPs with a fine size about 20 nm in diameter were selectively formed on the ZnO whiskers in the paper composites. As-prepared NiNPs@ZnO paper is much like an ordinary paper product, being flexible, lightweight, and easy to handle. The NiNPs@ZnO paper composites exhibited excellent catalytic performance in the steam reforming of propane, and produced hydrogen more efficiently than commercial pellet-type nickel catalysts. These results are possibly attributed both to highly active NiNPs synthesized in situ and to the uniform flow of reactants inside a microporous paper structure.