Download or read book Titania supported Vanadia Catalysts for the Selective Oxidation of Omikron xylene to Phthalic Anhydride written by Marc G. Nobbenhuis and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Titania supported Vanadia Catalysts for the Selective Oxidation of O xylene to Phthalic Anhydride written by Marc Gerard Nobbenhuis and published by . This book was released on 1993 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book N Pentane and 1 Pentene Selective Oxidation Over Molybdena and Vanadia Catalysts Supported on Sol Gel Titania Silica Mixed Oxides written by Rama Venkatachalam and published by . This book was released on 2000 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopic Studies of Titania Supported Vanadia Catalysts written by Andrew M. Ward and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Catalytic Oxidation of 1 2 Dichlorobenzene Over Vanadium Oxide Supported on Titania written by Chul-Hoon Cho and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Understanding the Effect of Modifying Elements in Supported Vanadia Bilayered Catalysts for Methanol Oxidation to Formaldehyde written by William Collins Vining and published by . This book was released on 2011 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of heterogeneous catalysis has long been interested in understanding the role of site structure on reactivity and selectivity for the rational design of catalysts. Vanadia is of particular interest because of its potential to be highly active and selective for a variety of reactions, such as oxidative dehydrogenation of alkanes to alkenes, or the oxidation of n-butane to maleic anhydride. When supported, vanadia can exist in several environments depending on its surface coverage. At the lowest loadings, below 2 V/nm2, the vanadium exists predominantly in well dispersed, tetrahedral structures with 3 V-O-support bonds and 1 V=O bond. At higher loadings, above 2 V/nm2, V-O-V bonds form on the surface, and at loadings above 7 V/nm2, the vanadia begins to form 3 dimensional domains of V2O5. Methanol oxidation rates over catalysts with varying vanadia loadings have shown no significant effect of the V surface density on the formaldehyde formation rate. However, significant differences in the formaldehyde production rates are observed for different supports. Changing the support from silica to titania or zirconia, will result in increases in the production of formaldehyde from methanol by over an order of magnitude for similar vanadia surface coverages. These differences in rate are observed even though the reaction mechanism is believed to be the same regardless of the support. The mechanism is thought to proceed as follows. First methanol dissociatively adsorbs across a V-O-support bond, producing V-OCH3 and M-OH (M = Si, Ti, Zr, Ce) in a quasi-equilibrated step. Next a surface oxygen abstracts hydrogen from the methoxy group in the rate determining step, and formaldehyde desorbs. The final steps are fast and involve the production of H2O from neighboring hydroxyls and the reoxidation of the catalyst by gas-phase oxygen. When vanadia is supported on bulk TiO2, ZrO2, or CeO2, the support surface area is relatively small (2̃00 m2/g at its highest), and the bulk support causes side reactions which make it difficult to understand the role of the vanadia. Furthermore, by using a bulk support, only the vanadia surface coverage can be varied, such that the effect of different V structures can be elucidated, but not that of V-O-M bonds. Therefore, high surface area silica with a variable coverage of two-dimensional TiO2, ZrO2, and CeO2 layers are used to support isolated vanadate structures to vary the quantity of vanadia bound to the modifying layer. These bilayered catalysts can be used to determine the effect of the V-O-support bonds on the formaldehyde production rate. Three mesoporous silica supports, MCM-48 (1550 m2/g), MCM-41 (1353 m2/g), and SBA-15 (700 m2/g) were used as the high surface area silica. Ti was grafted to the MCM-48 surface using Ti(OiPr)4 and a maximum surface coverage of 2.8 Ti/nm2 was obtained after 3 graftings. The grafting of zirconium was performed using Zr-2-methyl-2-butoxide on MCM-41, and a maximum loading of 2.1 Zr/nm2 was achieved after 3 graftings. The final modifying element, cerium, was grafted onto SBA-15 using Ce(OtBu)4 for a maximum surface coverage of 0.9 Ce nm-2. After treating the MOx/SiO2 (M = Ti, Zr, Ce) samples in air to remove any organic ligands, OV(OiPr)3 was grafted onto the MOx/SiO2 (M = Ti, Zr, Ce) support to achieve the desired V surface coverage of approx. 0.7 V/nm2. The resulting catalysts contain amorphous two-dimensional layers of TiO2, ZrO2, or CeO2 with V existing in a pseudo-tetrahedral structure on the surface. As the surface density of the modifying element layer increases, the quantity of vanadia bound to TiO2, ZrO2, or CeO2 increases. For the VOx/ZrO2/SiO2 catalysts, the fraction of vanadia bound to the zirconia layer was able to be quantified and determined to be 35% of all V for a Zr surface density of 2.8 Zr nm-2. Even for small quantities of modifying elements (0.2 M nm-2), the apparent rate constant for formaldehyde production on VOx/MO2/SiO2 (M = Ti, Zr, Ce) is an order of magnitude higher than for VOx/SiO2 catalysts at the same V surface density. Regardless of the modifying element used, the increase in apparent rate constant is comparable for all catalysts. As the modifying element surface density is increased, the apparent rate constant also increases, which is a result of an increasing fraction of V bound to the MOx layer. Each of these bilayered catalysts can be described using a two-site model of VOx/SiO2 and VOx/MO2 (M = Ti, Zr, Ce) with the latter being responsible for the increased apparent rate constant. This higher activity for the VOx/MO2 site is due to a lower apparent activation energy. For VOx/SiO2, the apparent activation energy is 23 kcal mol-1, but is approximately 17 kcal mol-1 for VOx/MO2 sites. The apparent activation energy can be expressed as the sum of the heat of methanol adsorption and the activation energy for H-abstraction. My results indicate that the lower apparent activation energy observed for the bilayered catalysts is a result of a decrease in the activation energy for H-abstraction. This lower energy pathway occurs because the MOx layer can abstract H from surface methoxy groups. For VOx/SiO2, however, the vanadyl oxygen abstracts H in a higher energy step.
Download or read book A Model Catalyst Investigation of Mass selected Vanadium and Vanadium Oxide Clusters Deposited on a Titanium Dioxide 110 1x1 Surface written by Scott P. Price and published by . This book was released on 2011 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vanadium oxide particles supported on titania are known to catalyze a number of reactions, including the selective oxidation of methanol to formaldehyde. Although the catalytic activity of this system has been widely studied, several questions related to the exact compositions and structures of the active species remain unanswered. In an effort to gain a deeper fundamental understanding of these catalysts, we utilize a unique apparatus which allows us to deposit mass-selected Vx and VxOy clusters on single-crystal rutile TiO2(110)-(1x1) in ultra high vacuum.
Download or read book A Surface Science Approach to Understanding Supported Vandia Catalysts written by Gordon Sek-Yin Wong and published by . This book was released on 2003 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Model Vanadium phosphorous oxygen Catalysts for the Selective Oxidation of C4 Hydrocarbons to Maleic Anhydride written by Thomas Patrick Moser and published by . This book was released on 1986 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Anagram Solver written by Bloomsbury Publishing and published by Bloomsbury Publishing. This book was released on 2009-01-01 with total page 719 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anagram Solver is the essential guide to cracking all types of quiz and crossword featuring anagrams. Containing over 200,000 words and phrases, Anagram Solver includes plural noun forms, palindromes, idioms, first names and all parts of speech. Anagrams are grouped by the number of letters they contain with the letters set out in alphabetical order so that once the letters of an anagram are arranged alphabetically, finding the solution is as easy as locating the word in a dictionary.
Download or read book Antifascisms written by David Ward and published by Fairleigh Dickinson Univ Press. This book was released on 1996 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an in-depth analysis of three of the most crucial years in twentieth-century Italian history, the years 1943-46. After more than two decades of a Fascist regime and a disastrous war experience during which Italy changed sides, these years saw the laying of the political and cultural foundations for what has since become known as Italy's First Republic. Drawing on texts from the literature, film, journalism, and political debate of the period, Antifascisms offers a thorough survey of the personalities and positions that informed the decisions taken in this crucial phase of modern Italian history.
Download or read book Type Typo written by and published by Omair Nazir. This book was released on with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Alphaherpesviruses written by Sandra Knowles Weller and published by Caister Academic Press Limited. This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alphaherpesviruses are a fascinating group of DNA viruses that includes important human pathogens such as herpes simplex virus type 1 (HSV-1), HSV-2, and varicella-zoster virus (VZV): the causative agents of cold sores, genital ulcerous disease, and chickenpox/shingles, respectively. A key attribute of these viruses is their ability to establish lifelong latent infection in the peripheral nervous system of the host. Such persistence requires subversion of the host's immune system and intrinsic antiviral defense mechanisms. Understanding the mechanisms of the immune evasion and what triggers viral reactivation is a major challenge for today's researchers. This has prompted enormous research efforts into understanding the molecular and cellular biology of these viruses. This up-to-date and comprehensive volume aims to distill the most important research in this area providing a timely overview of the field. Topics covered include: transcriptional regulation, DNA replication, translational control, virus entry and capsid assembly, the role of microRNAs in infection and oncolytic vectors for cancer therapy. In addition there is coverage of virus-host interactions, including apoptosis, subversion of host protein quality control and DNA damage response pathways, autophagy, establishment and reactivation from latency, interferon responses, immunity and vaccine development. Essential reading for everyone working with alphaherpesviruses and of interest to all virologists working on latent infections.
Download or read book Sisters Super Creeps and Slushy Gushy Love Songs written by Karen McCombie and published by . This book was released on 2011 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ally knows her super-efficient big sis Linn finds their chaotic family a bit ... exasperating. But when Linn falls for Q, the tearaway lead singer in a local band, all her sensible ways go out of the window. Everyone else can see that Q's a creep, but does Ally have the courage to burst Linn's heart-shaped bubble?
Download or read book Crossword Solver written by Anne Stibbs and published by Bloomsbury Pub Limited. This book was released on 2000 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: An aid to solving crosswords. It contains over 100,000 potential solutions, including plurals, comparative and superlative adjectives, and inflections of verbs. The list extends to first names, place names and technical terms, euphemisms and compound expressions, as well as abbreviations.
Download or read book The Boob Book written by and published by Chronicle Books. This book was released on 2020-01-07 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Featuring 30 types of breasts, The Boob Book is an illustrated celebration of womanhood and the boobs that come with it. Scattered throughout are boob miscellany: a boob personality flow chart, boob facts, boob self-care tips, a roundup of bras, types of nipples, a boob doodle, and illustrated ways we show off the goods. This joyful book features breasts of all colors and sizes—from "The Handful" to "The Mom-To-Be" to "The Small but Mighty"—showing women that every boob type is weird, beautiful, and natural. • An illustrated love letter to a girl's breast friend • Filled with fun and interactive boob-related miscellany, like a boob personality test (are you a "Chillaxer" or a "Handful"?), boob facts, and breast self-care tips • Light, celebratory, and a little cheeky—but ultimately sincere Let's hear it for our bosom buddies. Our mammary mamas. Our breasts-in-arms. From small and mighty to large and in charge to long, short, hairy, bumpy, or any boobs in between, this book uplifts them all. • A perfect book for women of all generations—from friends to mothers and daughters—or anyone who wants to send some extra support and love to their ladies • Ideal for anyone who needs a boob-size boost • Great for those who enjoyed Feminist Activity Book by Gemma Correll, Celebrating You: (And the Beautiful Person You Are) by M. H. Clark, and Gross Anatomy: Dispatches from the Front (and Back) by Mara Altman
