Effects of different silica intermediate layers for hydrogen diffusion enhancement of palladium membranes applied to porous stainless steel support

Porous stainless steel (SUS) supports were modified with double intermediate layers, silicalite-1 and γ-alumina, to enhance the hydrogen diffusion of a thin palladium membrane. One of layers, silicalite-1, was prepared using the hydrothermal synthetic method on porous SUS supports. The differences in expansion/contraction behaviors caused by different thermal coefficients of expansion between silicalite-1 and the SUS resulted in a lowering of the durability of the membrane. Intermediates layers of mesoporous MCM-48 powders or commercial spherical non-porous silica particles were then applied to porous SUS supports via aspiration, γ-alumina was introduced by dip-coating, and the Pd membrane was subjected to electro-less plating. H2 permeance of the Pd membrane (membrane thickness: 11 μm) containing spherical silica particles was around 10 × 10−6 mol·m−2·s−1·Pa−1 at 600 °C, which was higher than that of the Pd membrane (membrane thickness: 7 μm) containing MCM-48. The durability of the Pd membrane containing spherical silica particles was higher than that of the version containing MCM-48 powders. These results suggest that commercial spherical non-porous silica particles will uniformly occupy the pores of the SUS tubes and enhance the H2 permeance and durability of the Pd membrane

CATALYTIC ACTIVITY AND COKING RESISTANCE ON HYDROXYAPATITE FOR THE OXIDATIVE DEHYDROGENATION OF ISOBUTANE

Hydroxyapatite (HAp) samples were prepared from precursor solutions with different Ca/P molar ratios. The HAp samples were utilized as catalysts for the oxidative dehydrogenation (ODH) of isobutane. Also, the HAp samples were characterized by N2 and H2O adsorption-desorption measurements, X-ray diffraction, inductively coupled plasma optical emission spectrometry, thermogravimetry-differential thermal analyses, and temperature-programmed oxidation (TPO). The Ca/P molar ratio of the precursor solution had a major influence on the catalytic activity and coking resistance ability. The HAp catalyst prepared from the stoichiometric precursor solution [HAp (1.67)] showed the highest isobutene yield. Furthermore, the white color of HAp (1.67) remained unchanged during the ODH of isobutene, indicating the absence of coke on the surface of HAp (1.67) after the reaction and its higher coking resistance ability. The results of the TPO measurements showed that the HAp (1.67) catalyst possesses the strongest oxidation ability which is likely related to its higher coking resistance ability

Hydrogen Permeability of Palladium Membrane for Steam-Reforming of Bio-Ethanol

A Palladium membrane was prepared by electro-less plating method on porous stainless steel. The catalytic hydrogen production by steam-reforming of biomass-derived ethanol (bio-ethanol) using a Pd membrane was analyzed by comparing it with those for the reaction using reagent ethanol (the reference sample). And the hydrogen permeability of the palladium membrane was investigated using the same palladium membrane (H2/He selectivity = 249, at ΔP = 0.10 MPa, 873 K). As a result, for bio-ethanol, deposited carbon had a negative influence on the hydrogen-permeability of the palladium membrane and hydrogen purity. The sulfur content in the bio-ethanol may have promoted carbon deposition. By using a palladium membrane, it was confirmed that H2 yield (%) was increased. It can be attributed that methane was converted from ethanol and produced more hydrogen by steam reforming, due to the in situ removal of hydrogen from the reaction location

IR SPECTROSCOPIC ANALYSIS OF THERMAL BEHAVIOR OF ADSORBED WATER ON Y-TYPE ZEOLITE

In this study, we measured the IR spectra of water adsorbed at a differential temperature under constant pressure. Our purpose is to present a simple estimation method for the recycled temperature condition of water adsorbents. For a NaY zeolite, the IR integrated intensity of the bending vibration band of adsorbed water was increased with a decrease of temperature. The IR spectra were measured from 230℃ to 30℃ for several ion-exchanged Y-type zeolites. On the other hand, the adsorption isotherms of water on these zeolites were measured at 30℃. The result of this work is that the best correlation between the IR integrated intensity and the amount of adsorbed water was found for some of the zeolites. We concluded that the obtained correlation equation could easily estimate the amount of water desorbed between arbitrary temperatures

Conversion of Normal Ly-1-Positive B-Lineage Cells into Ly-1-Positive Macrophages in Long-Term Bone Marrow Cultures

We obtained eight different cell lines in the long-term bone marrow culture system that showed a germ-line configuration of the joining (J) region segments of the Ig heavy-chain (IgH) genes. Their surface markers were CD45R+, Ly-1+, Lyb-2+, cIgM-, sIgM-, Ia-, Thy-1-, Mac-1-, and IL-2R (Tac)+. Use of very young mice and the presence of IL-5 were important for preferential promotion of the survival of B-lineage lymphocytes bearing the Ly-1 markers. When we treated two of them (J8 and J10) with 5-azacytidine for 24 h followed by co-culture with stromal cells and IL-.5, they became Ly-1+, sIgM+ B cells, and Ly-1+, Mac-1+ macrophagelike cells, respectively. After other early lymphoid lines (J1, J8, and J13) were maintained by co-culture with ST2 and IL-5 for more than a year, they showed a heterogeneous DNA rearrangement profile of the J region segment of the IgH gene, although only J13 rearranged the κ-light chain gene. Northern blot analysis revealed that these cell lines expressed Cμ-mRNA, and λ5-mRNA, consistent with normal pre-B cells. Intriguingly, J1, J8, and J13 expressed c-fms mRNA constitutively. When J13 cells were co-cultured with ST2 and GM-CSF in place of ST2 and IL-5, they acquired Mac-1 expression and retained Ly-1 expression. They were morphologically macrophages, nonspecific-esterase-positive, and showed phagocytosis of latex beads. These results support evidence for a close relationship between the myeloid and Ly-1+ B-cell pathways of differentiation, and indicate that our IL- 5-dependent clones are multipotential intermediates in differentiation from pro-B cells to B cells and macrophages

High thermal-stability ceria synthesized via thermal-hydrolysis route and methane-combustion performance

Enhancement of the thermal stability of a catalyst is an efficient way to improve the catalytic activity of a catalytic reaction performed at high temperature. In this study, cerium oxide (ceria, CeO2) with a high thermal stability was synthesized by controlling the agglomeration of the primary particles via the thermal hydrolysis of ceric nitrate, accompanied by testing for the catalytic combustion of methane (CH4). The specific surface area of this material after calcination at 1,173K for 5 h was 50m2/g, which was much higher than that of the two reference materials (ceria made via precipitation of cerous nitrate using aqueous ammonia at 4.1m2/g, and the Japan reference catalyst JRC-CEO-1 at 1.4m2/g). The ceria made via thermal hydrolysis showed high crystallinity and a much higher pore volume, which resulted in excellent thermal resistance. For O2 conversion in ceria, catalyzed CH4 combustion at 923 K, the ceria created in this study demonstrated higher activity than that for either reference. The high CH4 combustion performance was due to the high specific surface area and to a superior oxygen storage capacity (OSC) even after a combustion test

Modifying SBA-15 with Binary Elements of Chromium and Molybdenum for Improved Catalytic Performance in the Oxidative Dehydrogenation of Isobutane to Isobutene

In the oxidative dehydrogenation of isobutane to isobutene, selectivity and stability were improved by introducing chromium and molybdenum into SBA-15. The direct synthesis method (DM) was used to introduce these binary elements into SBA-15. Use of the DM resulted in a higher specific surface area of the catalyst and a greater dispersion of chromium and molybdenum species compared with a corresponding binary catalyst prepared using the incipient wetness impregnation method (IM). Selectivity to isobutene was improved, along with a decrease in the selectivities to CO and CO2 with the introduction of greater amounts of molybdenum, which suggests that molybdenum must suppress the tendency of isobutene to over-oxidate to either CO or CO2. The molybdenum species must be in close proximity to the chromium species, which results in the formation of an active Cr-O-Mo site

アタラシイ フチャク ヨクセイ ヒョウメン ショリ オ ホドコシタ コウ ヒョウメン エノ フンタイ ノ フチャク キョドウ ノ カイセキ

In this paper, we examined the relationship between surface roughness and particle adhesion behavior by a proposed experiment. Five kinds of SiO2 spherical powders (0.2μm-2.0μm) and stainless steel plates with seven kinds of surface roughness were used for the investigation. The adhesion ratios of SiO2 powders to polished stainless steel plates were measured. The adhesion ratios depend on the surface roughness and the particle diameters. The adhered particles on the steel plate were observed by SEM in order to examine the adhesion mechanism of SiO2 particle on the polished stainless plate substrate. As the result, 0.4-1.0 μm particles were easy to adhere independent of surface roughness and nominal powder diameter. The result indicates that adhesion behavior of powder depends on the adhesion force of 0.4-1.0 μm particles that are changed by the surface roughness of the steel plate