88 research outputs found

    The Catalytic Conversion of 1,2-Propandiol to Propanal on FSM-16 Molded by Wet-Treatment and Pressurization

    Get PDF
    The catalytic conversion of 1,2-propandiol to propanal is examined using FSM-16 particles (0.85-1.70 mm) molded by wet-treatment and pressurization. When FSM-16 was molded with 0.6 g of pressurization and supplied to the catalytic conversion of 1,2-propandiol at 673 K, this system resulted in a 94.8% conversion of 1,2-propandiol and 90.5% selectivity to propanal at 0.25 h on-stream, which was the maximum amount of activity. However, at 4.50 h on-stream, the activity decreased extremely to deactivation 19.9% conversion of 1,2-propandiol and 84.7% selectivity to propanal. In contrast, when FSM-16 molded with wet-treatment (0.15 g) was used for the conversion at 573 K, activity was greatly increased and stable 98.6% conversion of 1,2-propandiol and 56.2% selectivity to propanal at 0.25 h on-stream followed by 91.9% and 52.5%, respectively, at 4.50 h on-stream. The hexagonal structure of FSM-16 was suggested to have contributed to the suitable conversion of 1,2-propandiol to propanal

    Acidic Properties of Various Silica Catalysts Doped with Chromium for the Oxidative Dehydrogenation of Isobutane to Isobutene

    Get PDF
    Although previous researchers have found that FSM-16 (#16 Folded Sheet Mesoporous material) doped with chromium and related Cr-doped silica catalysts has shown great activity for the oxidative dehydrogenation of isobutane to isobutene, information on the nature of these catalysts is insufficient. For this study, three types of Cr-doped silica catalysts were prepared by applying the template ion exchange method. CrOx/FSM-16 and CrOx/SiO2 were used as references. These catalysts were used for oxidative dehydrogenation, which was then characterized via various techniques. The most active catalyst was Cr-doped silica, which did not have the hexagonal structure that is characteristic of mesoporous FSM-16. Various characterizations showed that the catalytic activity of the Cr-species, stemmed from a weak acidic nature and a redox nature that originated from the combination of silicate and a Cr cation, as opposed to the hexagonal structure and strong acidic nature of FSM-16

    Effects of Acidic Properties of FSM-16 on the Catalytic Conversion of 1,2-Propandiol in the Presence and Absence of Hydrogen

    Get PDF
    We have earlier showed how the catalytic conversion of 1,2-propandiol to propanal using FSM-16 (#16 folded sheets of mesoporous materials) when molded by wet treatment proceeded more favorably than when using FSM-16 molded by pressurization, while no comparison using other typical acidic catalysts and no examination of the acidic properties of FSM-16 was carried out. In the present study, the conversion using FSM-16 molded by wet treatment and pressurization was compared with that obtained by using typical acidic catalysts such as SiW12O40/SiO2 and MCM-41 (#41 of Mobil Composition of Matter) together with amorphous SiO2. Among these catalysts, FSM-16 molded by wet treatment showed the most suitable catalytic activity. In order to examine the effect of the molding procedure for FSM-16 on its structural and acidic properties, FSM-16 molded by both methods was examined using NH3-TPD, in situ FT-IR using NH3 as a probe molecule, and Hammett indicators together with XRD and TEM. According to Zaitsev's rule, the present conversion should afford acetone rather than propanal, which indicates that it would proceed via hydro cracking. Therefore, the conversion of 1,2-propandiol using FSM-16 was also examined in the presence and absence of hydrogen. Furthermore, hydration reactions of 1- and 2-propanol when using FMS-16 were examined. Based on the results obtained from this investigation, it was concluded that the conversion using a more acidic FSM-16 molded by wet treatment proceeded through dehydration rather than through hydro cracking

    The Oxidative Esterification of Propionaldehyde to Methyl Propionate in the Liquid-Phase Using a Heterogeneous Palladium Catalyst

    Get PDF
    The optimization of the oxidative esterification of propionaldehyde to methyl propionate using a supported palladium catalyst in methanol under heavy-metal-free and pressurized-oxygen conditions, which we recently reported in a previous paper, were carried out together with a study of the reaction route, the nature of the catalytic active sites, and the effect of the support. In our previous paper, we reported significantly improved activity for oxidative esterification using commercially available 5%Pd/Al2O3 at 1.5 MPa of O2 gas and 333 K and emphasized that the doping of 5%Pd/Al2O3 with lead was not needed for the reaction system, but we could not improve the activity that was reported when using 5%Pd/γ-Al2O3 doped with 5% Pb (a 93.2% conversion of propionaldehyde, 76.8% selectivity for methyl propionate and a 71.6% yield of methyl propionate) at 0.3 MPa of O2 gas and 353 K, as reported by another laboratory. In the present study, however, we exceeded those values and obtained a 98.3% conversion of propionaldehyde, 75.3% selectivity for methyl propionate and a 74.0% yield of methyl propionate using 5%Pd/γ-Al2O3 undoped with Pb at 1.5 MPa of O2 gas and 333 K. It should be noted that, in the preparation of the present 5%Pd/γ-Al2O3, Pd was doped onto Al2O3 that had been previously treated with aqueous NaOH. Another active alumina support,η-Al2O3, prepared from boehmite, afforded activity that was substantially lower than that of γ-Al2O3 and depended on the calcination temperature of boehmite to η-Al2O3. When using various concentrations of CH3OH in the aqueous reaction solution, the oxidative esterification proceeded through the formation of propionic acid. To determine why the Al2O3 support afforded better activity than the active carbon support, Pd/Al2O3 and Pd/C catalysts were examined by XAFS (X-ray absorption fine structure). XAFS revealed that Pd on Al2O3 shows a better redox nature than Pd on C, which resulted in activity on Pd/Al2O3 that was better than that on Pd/C

    第2節 日本・ベトナム出土のベトナム焼締陶器の放射化分析(第6章 ベトナム陶磁器の理化学的分析)(III ベトナム陶磁器の理化学的分析)(ベトナムの日本町 : ホイアンの考古学調査)

    Get PDF
    Chemical studies on the Vietnamese pottery sherds from Vietnam and Japan were carried out to know their provenance, kilns for making them, through the trace element contents by instrumental neutron activation analysis. The Vietnamese pottery sherds used are 14 samples collected on the surface of four old kiln sites (My Xuyen and Phuoc tich, Hue ; Phuoc Ly, Quang tri ; and My Cuong, QuangBinh) and 7 samples excavated at three archaeological sites (Thanh Ha, Hue ; and Dinh Campho and Thanh Chiem, Hoi An) in the central Vietnam and also 13 samples excavated at four archaeological sites in different places in Japan (Nagasaki, Sakai, Kyoto City and Heiankyo, Kyoto). Contents of 12 trace elements such as Rb, Cs, La, Ce, Sm, Eu, Lu, Th, Hf, Co, Sc and Cr, and two major elements Na and Fe in the Vietnamese pottery sherds were analyzed by instrumental neutron activation analysis. These samples (ca.30~50mg) were irradiated for 24 hours intermittently at Rikkyo University Research Reactor, TRIGA Mark n. The activated samples were measured by gamma-ray spectrometry using a high resolution Ge (Li) detector coupled with a 4096 channel analyzer. As a result of the cluster analysis of the element contents of the pottery sherds, probably 13 samples including four Vietnam and nine from Japan, were identified as those from the kilns of My Xuyen, Phuoc tich and Phuoc Ly. It is interesting there are no samples identified to My Xuyen kiln site, supposed to be the late seventeenth century. It agreed with the fact all of the samples from Japan were estimated earlier than that time. Also five samples from both countries have no adequate sources, so it suggests some of undiscovered kiln sites still remain in the central part of Vietnam

    CNVs in Three Psychiatric Disorders

    Get PDF
    BACKGROUND: We aimed to determine the similarities and differences in the roles of genic and regulatory copy number variations (CNVs) in bipolar disorder (BD), schizophrenia (SCZ), and autism spectrum disorder (ASD). METHODS: Based on high-resolution CNV data from 8708 Japanese samples, we performed to our knowledge the largest cross-disorder analysis of genic and regulatory CNVs in BD, SCZ, and ASD. RESULTS: In genic CNVs, we found an increased burden of smaller (500 kb) exonic CNVs in SCZ/ASD. Pathogenic CNVs linked to neurodevelopmental disorders were significantly associated with the risk for each disorder, but BD and SCZ/ASD differed in terms of the effect size (smaller in BD) and subtype distribution of CNVs linked to neurodevelopmental disorders. We identified 3 synaptic genes (DLG2, PCDH15, and ASTN2) as risk factors for BD. Whereas gene set analysis showed that BD-associated pathways were restricted to chromatin biology, SCZ and ASD involved more extensive and similar pathways. Nevertheless, a correlation analysis of gene set results indicated weak but significant pathway similarities between BD and SCZ or ASD (r = 0.25–0.31). In SCZ and ASD, but not BD, CNVs were significantly enriched in enhancers and promoters in brain tissue. CONCLUSIONS: BD and SCZ/ASD differ in terms of CNV burden, characteristics of CNVs linked to neurodevelopmental disorders, and regulatory CNVs. On the other hand, they have shared molecular mechanisms, including chromatin biology. The BD risk genes identified here could provide insight into the pathogenesis of BD

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

    Get PDF
    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    The Constrained Maximal Expression Level Owing to Haploidy Shapes Gene Content on the Mammalian X Chromosome.

    Get PDF
    X chromosomes are unusual in many regards, not least of which is their nonrandom gene content. The causes of this bias are commonly discussed in the context of sexual antagonism and the avoidance of activity in the male germline. Here, we examine the notion that, at least in some taxa, functionally biased gene content may more profoundly be shaped by limits imposed on gene expression owing to haploid expression of the X chromosome. Notably, if the X, as in primates, is transcribed at rates comparable to the ancestral rate (per promoter) prior to the X chromosome formation, then the X is not a tolerable environment for genes with very high maximal net levels of expression, owing to transcriptional traffic jams. We test this hypothesis using The Encyclopedia of DNA Elements (ENCODE) and data from the Functional Annotation of the Mammalian Genome (FANTOM5) project. As predicted, the maximal expression of human X-linked genes is much lower than that of genes on autosomes: on average, maximal expression is three times lower on the X chromosome than on autosomes. Similarly, autosome-to-X retroposition events are associated with lower maximal expression of retrogenes on the X than seen for X-to-autosome retrogenes on autosomes. Also as expected, X-linked genes have a lesser degree of increase in gene expression than autosomal ones (compared to the human/Chimpanzee common ancestor) if highly expressed, but not if lowly expressed. The traffic jam model also explains the known lower breadth of expression for genes on the X (and the Z of birds), as genes with broad expression are, on average, those with high maximal expression. As then further predicted, highly expressed tissue-specific genes are also rare on the X and broadly expressed genes on the X tend to be lowly expressed, both indicating that the trend is shaped by the maximal expression level not the breadth of expression per se. Importantly, a limit to the maximal expression level explains biased tissue of expression profiles of X-linked genes. Tissues whose tissue-specific genes are very highly expressed (e.g., secretory tissues, tissues abundant in structural proteins) are also tissues in which gene expression is relatively rare on the X chromosome. These trends cannot be fully accounted for in terms of alternative models of biased expression. In conclusion, the notion that it is hard for genes on the Therian X to be highly expressed, owing to transcriptional traffic jams, provides a simple yet robustly supported rationale of many peculiar features of X's gene content, gene expression, and evolution
    corecore