Nanoparticles of tungsten as low-cost monometallic catalyst for selective hydrogenation of 3-hexyne

Low-cost tungsten monometallic catalysts containing variable amounts of metal (4.5, 7.1 and 8.5%W) were prepared by impregnating alumina with ammonium metatungstate as an inexpensive precursor. The catalysts were characterized using ICP, XPS, XRD, TPR and hydrogen chemisorption. These techniques revealed mainly WO3-Al2O3 (W6+) species on the surface. The effects of the content of W nanoparticles and reaction temperature on activity and selectivity for the partial hydrogenation of 3-hexyne, a non-terminal alkyne, were assessed under moderate conditions of temperature and pressure. The monometallic catalysts prepared were found to be active and stereoselective for the production of (Z )-3-hexene, had the following order: 7.1WN/A > 8.5 WN/A ≥ 4.5 WN/A. Additionally, the performance of the synthesized xWN/A catalysts exhibited high sensitivity to temperature variation. In all cases, the maximum 3-hexyne total conversion and selectivity was achieved at 323 K. The performance of the catalysts was considered to be a consequence of two phenomena: a) the electronic effects, related to the high charge of W (+6), causing an intensive dipole moment in the hydrogen molecule (van der Waals forces) and leading to heterolytic bond rupture; the H+ and H- species generated approach a 3-hexyne adsorbate molecule and cause heterolytic rupture of the C≡C bond into C- = C+; and b) steric effects related to the high concentration of WO3 on 8.5WN/A that block the Al2O3 support. Catalyst deactivation was detected, starting at about 50 min of reaction time. Electrodeficient W6+ species are responsible for the formation of green oil at the surface level, blocking pores and active sites of the catalyst, particularly at low reaction temperatures (293 and 303 K). The resulting best catalyst, 7.1WN/A, has low fabrication cost and high selectivity for (Z )-3-hexene (94%) at 323 K. This selectivity is comparable to that of the classical and more expensive industrial Lindlar catalyst (5 wt% Pd). The alumina supported tungsten catalysts are low-cost potential replacements for the Lindlar industrial catalyst. These catalysts could also be used for preparing bimetallic W-Pd catalysts for selective hydrogenation of terminal and non-terminal alkynes.

Berlin, Germany, 1748 (Image 3 of 4) (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Plan de la ville de Berlin : levé et dessiné par ordre et privilege privatif du Roy sous la direction du Marchall Comte de Schmettau, par Hildner approuvé par l'Academie Royale de Science â Berlin ; gravé sous la direction de G.F. Schmidt Graveur du Roy. It was published by l'Academie Royale de Science â Berlin in 1748. Scale [ca. 1:6,500]. Covers Berlin, Germany. This layer is image 3 of 4 total images of the four sheet source map, representing the northwest portion of the map. Map in French and German.The image inside the map neatline is georeferenced to the surface of the earth and fit to the Deutsches Hauptdreiecksnetz (DHDN) 3-degree Gauss-Kruger Zone 4 coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, drainage, built-up areas and selected buildings, fortification, parks, cemeteries, ground cover, and more. Relief shown by hachures. Includes also view and inset engravings: Prospect du Stadt Berlin von Süden gegen Norden -- 1. Prospect des grossen Platzes von Opera Hausse 2. der Cathol. Kirche St. Hedwig 3. und einer Seite des Marggraff Henrich. Pallais -- Prospect der Neuen Schloss u Dohm Kirche -- Prospect des Neuen Königl. Printz Heinrich. Pallais den Opern Hausse gegen über.This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of originators, ground condition dates, scales, and map purposes.

Foraminiferal oxygen and carbon isotopic measurements from 5 sites of southern Atlantic and Pacific

The stratigraphy and paleoceanography of the late Miocene and early Pliocene have been examined at six sites in the South Atlantic and southwest Pacific oceans: Deep Sea Drilling Project (DSDP) sites 284, 516A, 519, 588, and 590 and two piston cores from Chain cruise 115. A consistent stratigraphy was developed among sites using graphic correlation, which resulted in age models for all sites that are tied to the revised paleomagnetic time scale of Berggren et al. (1985). Applying these chronologies, we assessed latitudinal and interocean contrasts in the stratigraphic ranges of late Miocene-early Pliocene planktonic foraminiferal and nanno - fossil datums. Salient stratigraphic results include (1) The last appearance datum (LAD) of Globoquadrina dehiscens is a late Miocene (approx. 6.4 Ma) event in the subtropics and is not useful for the placement of the Miocene/Pliocene (M/P) boundary in this biogeographic province. (2) The first appearance datum (FAD) of Globorotalia crassaformis occurred at 5.1 Ma in the South Atlantic near the M/P boundary, suggesting that Gr. crassaformis may have first evolved in the South Atlantic and later migrated to other regions. (3) In the southwest Pacific, the FADs of Gr. margaritae (5.97 Ma), Gr. puncticulata (5.09 Ma), and Gr. crassaformis (4.87 Ma) are significantly time transgressive between temperate and warm subtropical regions. Time lags of 1.0 m.y. were required for these species to adapt to physical and/or biotic conditions peripheral to their endemic biogeographic provinces. (4) Between the subtropics of the South Atlantic and southwest Pacific, many planktonic foraminiferal datums (FAD of Dentogloboquadrina altispira, Gr. cibaoensis, Gr. conomiozea, Gr. margaritae, and Gq. dehiscens and LAD of Gr. cibaoensis) markedly depart from the correlation suggested by magnetostratigraphy, indicating that these datum levels are unreliable for correlation between these ocean basins. (5) In contrast, available calcareous nannofossil datum levels fall on or near the paleomagnetic correlation line, indicating synchroneity of events within the subtropics. (6) Biostratigraphic, magnetic, and 87Sr/86Sr correlation between sites 588 and 519 and the M/P neostratotype at Capo Rossello, Sicily, suggests that the base of the Zanclean stratotype occurs at 5.1-5.0 Ma in the lower reversed subchron of the Gilbert, about 2-3 * 10**5 years above the Gilbert/Chron 5 boundary. Oxygen isotopic results from DSDP sites 284, 519, and CH115 piston cores confirm a prolonged benthic d18O increase in the latest Miocene between 5.6 and 5.0 Ma, as originally proposed by Shackleton and Kennett (1975). At DSDP site 588, the benthic d18O record in the latest Miocene is marked by high-frequency fluctuations with amplitude variations of 0.5per mill, and a long-period wavelength component of 400,000 years. Maximum d18O values, however, occurred during the late Miocene (Kapitean Stage) between 5.5 and 5.1 Ma. The late Miocene d18O changes resulted from mid- and high-latitude cooling and pulses of ice sheet expansion and contraction. Glacial events were most intense during the latest Miocene (Kapitean Stage), and occurred at 5.50-5.35 Ma and at 5.10 Ma. Glacial events are estimated to have lowered sea level by 40 to 60 m and contributed to the isolation and desiccation of the Mediterranean Basin during the late Messinian. Interglacial conditions prevailed at 5.2 Ma and between 5.0 and 4.1 Ma in the early Pliocene. The beginning of the Pliocene was marked by changes in many proxy climatic indicators at all sites, suggesting a prolonged interval of warm, interglacial conditions between 5.0 and 4.1 Ma during the earliest Pliocene.

(Table 4) Chemistry of iron-rich basalts from ODP Hole 106-648B

Analysis numbers 344-370, SAMF 12.5-12.7; 442-369, SAMF 12.7-12.9; 422-77, SAMF 12.9-13.1; 95-156, SAMF 13.1-13.3; 272-82, SAMF 13.3-13.5; 285-33, SAMF 13.5-13.7. Analyses are listed in depth order within each SAMF division.

Paleointensity of various DSDP sites (Table 3)

The existing database for paleointensity estimates of the ancient geomagnetic field contains more than 1500 data points collected through decades of effort. Despite the huge amount of work put into obtaining these data, there remains a strong bias in the age and global distribution of the data toward very young results from a few locations. Also, few of the data meet strict criteria for reliability and most are of unknown quality. In order to improve the age and spatial distribution of the paleointensity database, we have carried out paleointensity experiments on submarine basaltic glasses from a number of DSDP sites. Of particular interest are the sites that provide paleointensity data spanning the time period 0.3-5 Ma, a time of relatively few high quality published data points. Our new data are concordant with contemporaneous data from the published literature that meet minimum acceptance criteria, and the combined data set yields an average dipole moment of 5.49 +/- 2.36*10**22 Am**2. This average value is comparable to the average paleofield for the period 5-160 Ma (4.2 +/- 2.3*10**22 Am**2) (Juarez et al., 1998, doi:10.1038/29746) and is substantially less than the value of approximately 8*10**22 Am**2 often quoted for the last 5 Myr (e.g. McFadden and McElhinny (1982) J. Geomagn. Geoelectr. 34, 163-189; Goguitchaichvili et al., 1999, doi:10.1016/S0012-821X(99)00010-2).

(Table 3) Relative depth and age, CaCO3, d18O, d13C and Sr/Ca analysis from ODP Leg 130, 154 and 138

Interpretations of calcite strontium/calcium records in terms of ocean history and calcite diagenesis require distinguishing the effects on deep-sea calcite sediments of changes in ocean chemistry, of different mixes of calcite-depositing organisms as sediment contributors through time and space, and of the loss of Sr during diagenetic calcite recrystallization. In this paper Sr/Ca and d18O values of bulk calcium carbonate sediments are used to estimate the relative extent of calcite recrystallization in samples from four time points (core tops, 5.6, 9.4, and 37.1 Ma) at eight Ocean Drilling Program sites in the equatorial Atlantic (Ceara Rise) and equatorial Pacific (Ontong Java Plateau and two eastern equatorial Pacific sites). The possibility that site-to-site differences in calcite Sr/Ca at a given time point originated from temporal variations in ocean chemistry was eliminated by careful age control of samples for each time point, with sample ages differing by less than the oceanic residence times of Sr and Ca. The Sr/Ca and d18O values of 5.6- and 9.4-Ma samples from the less-carbonate-rich eastern equatorial Pacific sites and Ceara Rise Site 929 appear to be less diagenetically altered than the Sr/Ca and d18O values of contemporaneous samples from the more carbonate-rich sites. It is evident from these data that both Sr/Ca and d18O in bulk calcite have been diagenetically altered in some samples 5.6 Ma and older. These data indicate that noncarbonate sedimentary components, like clay and biogenic silica, have partially suppressed recrystallization at the lower carbonate sites. Sr/Ca data from the less altered, carbonate-poor sites indicate higher oceanic Sr/Ca relative to today at 5.6 and 9.4 Ma.

Engineering studies, pt. 1-5 ...

pt. 1. American stone arches.--pt. 2. Roman stone arches.--pt. 3. English stone arches.--pt. 4. French stone arches.--pt. 5. German and Austrian stone arches.

Tracts on political economy : viz. 1. Britain independent of commerce; 2. Agriculture the source of wealth; 3. The objections against the corn bill refuted; 4. Speech on the East India trade ; with prefatory remarks on the causes and cure of our present distresses, as originating from neglect of principles laid down in these works /

The tracts collected under the above title have individual title-pages. No. 1, 7th ed., 1808; no. 2, 1808; no. 3, 5th ed., 1815; no. 4, speech delivered 1812, no imprint date.

Minutes of the Supreme Executive Council of Pennsylvania, from its organization to the termination of the Revolution. [Mar. 4, 1777 - Dec. 20, 1790]

This set is indexed in the "General index to the Colonial records, in 16 volumes, and to the Pennsylvania archives, in 12 volumes ... by Samuel Hazard." Philadelphia, 1860.

Operator's manual : truck, lift, fork, gasoline, 4,000 lbs capacity, towmotor models 462SG4024-100 (solid tire) ... Army model MHE-191 ... FSN 3930-781-3856 ... 3930-073-9222.

"September 1964."

5-ton, 6x6, M39 series trucks (multifuel) : model, chassis, M40A2C ... NSN without winch, 2320-00-969-4114 ... NSN with winch, 2320-00-965-0321 ....

Includes index.

Public Lands Management Improvement Act of 1997 : hearings before the Subcommittee on Forests and Public Land Management of the Committee on Energy and Natural Resources, United States Senate, One Hundred Fifth Congress, first session, on S. 1253, to provide to the federal land management agencies the authority and capability to manage effectively the federal lands in accordance with the principles of multiple use and sustained yield, and for other purposes, October 30, 1997, December 15, 1997, February 3, 1998.

"April 23,1998, April 30, 1998, May 5, 1998, June 4, 1998, June 17, 1998"--Pt. 2.

Na 1 Nachlass Max Horkheimer, 802 - "Dialektik der Aufklärung" von Max Horkheimer und Theodor W. Adorno (p. XI 6.3 - XI 6.42)

3. Aus der "Dialektik der Aufklärung"; Kapitel: "Juliette oder Aufklärung und Moral". Typoskript mit dem Titel "Aufklärung und Rigorismus", mit handschriftlichen Korrekturen, 52 Blatt (2 Exemplare); 4. Aus der "Dialektik der Aufklärung"; Kapitel: "Kulturindustrie". Typoskript mit dem Titel "Das Schema der Massenkultur":; 4a) Typoskript mit handschriftlichen Korrekturen, 67 Blatt; 4b) Typoskript mit eigenen Korrekturen, 106 Blatt; 5. - 110. Gedruckte und ungedruckte Aufzeichnungen und Entwürfe zur "Dialektik der Aufklärung: Sammlungen A, B, C, D, die teilweise identisch sind; 5. - 42. Sammlung A: "Aphorismen"; 5. "Zum Problem der Bedürfnisse". Typoskript, 5 Blatt; 6. "Mensch und Tier". Typoskript mit eigenen Korrekturen, 12 Blatt; 7. "Propaganda". Typoskript, 2 Blatt; 8. "Straftheorie". Typoskript mit eigenen Korrekturen, 3 Blatt; 9. "Dichtung und Moral". Typoskript mit eigenen Korrekturen, 5 Blatt; 10. "Zur Genese der Dummheit". Typoskript, 3 Blatt; 11. "Interesse am Körper". Typoskript mit eigenen Korrekturen, 6 Blatt; 12. "Philosophie und Arbeitsteilung". Typoskript, 3 Blatt; 13. "Widersprüche". Typoskript, 4 Blatt; 14. "Geschichte der amerikanischen Arbeiterschaft". Typoskript, 1 Blatt; 15. "Feind". Typoskript, 2 Blatt; 16. "Gezeichnet". Typoskript mit eigenen Korrekturen, 2 Blatt; 17. "Erkenntnis und Sprache". Typoskript, 1 Blatt; 18. "Unmöglichkeit der Dichtung". Typoskript, 1 Blatt; 19. "Erbsünde und Kopula". Typoskript, 2 Blatt; 20. "Die Einseitigkeit der Negativität". Typoskript, 2 Blatt [= "Für Voltaire" in der "Dialektik der Aufklärung"]; 21. "Klassifikation". Typoskript mit eigenen Ergänzungen, 1 Blatt; 22. "Jüdischer Charakter". Typoskript mit eigenen Korrekturen, 1 Blatt; 23. "Lawine". Typoskript mit eigenen Korrekturen, 2 Blatt; 24. "Solidarität". Typoskript mit eigenen Korrekturen, 2 Blatt; 25. "Bewußtsein". Typoskript, 1 Blatt; 26. "Gegen Bescheidwissen". Typoskript, 1 Blatt; 27. "Der Gedanke". Typoskript, 1 Blatt; 28. "Quand-même". Typoskript, 2 Blatt; 29. "Leeres Erschrecken". Typoskript mit eigenen Korrekturen, 2 Blatt; 30. "Haupt- und Nebensatz". Typoskript, 3 Blatt; 31. "Verwandlung der Idee in Herrschaft". Typoskript mit eigenen Korrekturen, 5 Blatt; 32. "Isolierung durch Verkehr". Typoskript, 1 Blatt; 33. "Kampf und Gewaltlosigkeit". Typoskript, 6 Blatt; 34. "Zwei Welten". Typoskript, 2 Blatt; 35. "Zur Theorie der Gespenster". Typoskript, 1 Blatt; 36. "Notiz" [= "Umschlag der idealistischen Dialektik"]. Typoskript, 1 Blatt; 37. "Massengesellschaft". Typoskript, 1 Blatt; 38. "Tierpsychologie". Typoskript, 1 Blatt; 39. "Denkmale der Humanität". Typoskript mit eigenen Korrekturen, 1 Blatt; 40. "Physiognomik". Typoskript mit eigenen Korrekturen, 1 Blatt; 41. "Die Rackets und der Geist". Typoskript mit eigenen Korrekturen, 7 Blatt; 42. "Altmodisches Problem". Typoskript mit eigenen Korrekturen, 2 Blatt;