Facile Synthesis of Effcient and Selective Ruthenium Olefin Metathesis Catalysts with Sulfonate and Phosphate Ligands

A series of novel, air-stable ruthenium NHC catalysts with sulfonate and phosphate anions have been prepared easily in one pot at high yields using commercially available precursors. The catalysts were found to be effective for ring-opening metathesis polymerization, ring-closing metathesis, and cross-metathesis. The catalysts showed higher cis-selectivity in olefin cross-metathesis reactions as compared to earlier known ruthenium-based olefin metathesis catalysts, with allylbenzene and cis-1,4-diacetoxybutene as substrates

Solvent effects on Grubbs’ pre-catalyst initiation rates

Initiation rates for Grubbs and Grubbs-Hoveyda second generation pre-catalysts have been measured accurately in a range of solvents. Solvatochromic fitting reveals different dependencies on key solvent parameters for the two pre-catalysts, consistent with different mechanisms by which the Grubbs and Grubbs-Hoveyda pre-catalysts initiate

The use of niobia in oxidation catalysis

This paper summarises the background to work carried out at the University of Twente on the use of niobia as a catalyst for the oxidative dehydrogenation of propane to propylene and discusses the development of promoted niobia catalysts for this reaction. Results are also presented which illustrate the use of niobia in catalysts for other reactions such as the oxidative coupling of methane, the oxidative dehydrogenation of ethane and the oxidative dehydrogenation of methanol. It appears that niobia and niobia-modified catalysts, when used in high-temperature oxidation processes, can exhibit relatively high selectivities compared with more conventional catalysts

Angling policy and property rights in France : an economic approach

Diffusion du document : INRA Unité d'Economie et Sociologie rurales 4 Allée Adolphe Bobierre CS 61103 35011 Rennes cedex (FRA)Ronald Coase has shown that well-defined property rights and the absence of transaction costs ensure that bargaining can lead to efficient environment allocation. In France, as in most developed countries, fishing rights are well-defined and belong to land-owners. However in many cases these rights are traditionally given for free to anglers associations (AAPPMA). AAPPMA are the basic institutions in charge of angling management in France. In a first part we describe how private fishing rights are institutionally turned into public goods. This is the basis of the French democratic angling rule : fishing "everywhere, for everyons and at low cost".In a second part we analyze the economic drawbacks of foregone property rights. Two main external effects arise from the public nature of recreational fishing in France. First we deal with externalities between anglers, known as the "tragedy of the comrnons". Then we describe the extemal effects between land owners (mostly farmers) and anglers. This leads to pollution and loss of environmental services

Identification of single-site gold catalysis in acetylene hydrochlorination

There remains considerable debate over the active form of gold under operating conditions of a recently validated gold catalyst for acetylene hydrochlorination. We have performed an in situ x-ray absorption fine structure study of gold/carbon (Au/C) catalysts under acetylene hydrochlorination reaction conditions and show that highly active catalysts comprise single-site cationic Au entities whose activity correlates with the ratio of Au(I):Au(III) present. We demonstrate that these Au/C catalysts are supported analogs of single-site homogeneous Au catalysts and propose a mechanism, supported by computational modeling, based on a redox couple of Au(I)-Au(III) species. View Full Tex

Hydrogen production by methanol steam reforming on NiSn/MgO-Al 2O3 catalysts: The role of MgO addition

The effect of the magnesia loading on the surface structure and catalytic properties of NiSn/MgO-Al2O3 catalysts for hydrogen production by methanol steam reforming has been investigated. The catalysts have been obtained by impregnation of γ-Al2O3 by the incipient wetness method, with variation of the MgO content. X-ray diffraction (XRD), BET surface area and H2-temperature programmed reduction (TPR) have been used to characterise the prepared catalysts. From this, it has been concluded that the incorporation of MgO results in the formation of MgAl 2O4 spinel, which modifies the acid-base properties of the catalysts. The formation of Ni-Sn alloys after the reductive pre-treatment has also been evidenced. The influence of the temperature of reaction and of the MgO loading on the hydrogen production by reforming of methanol has been established. Moreover, tests of catalytic stability have been carried out for more than 20 h. The carbonaceous deposits have been examined by temperature-programmed oxidation (TPO). The analysis of the catalysts after reaction has confirmed the low level of carbon formation on these catalysts. In no case, carbon nanotubes have been detected on the solids.Junta de Andalucía TEP106Ministerio de Ciencia e Innovación ENE2009-14522-C05-0

Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers

Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed

Electro-oxidation of Ethanol on Carbon Supported PtSn and PtSnNi Catalysts

Even though platinum is known as an active electro-catalyst for ethanol oxidation at low temperatures (< 100 oC), choosing the electrode material for ethanol electro-oxidation is a crucial issue. It is due to its property which easily poisoned by a strong adsorbed species such as CO. PtSn-based electro-catalysts have been identified as better catalysts for ethanol electro-oxidation. The third material is supposed to improved binary catalysts performance. This work presents a study of the ethanol electro-oxidation on carbon supported Pt-Sn and Pt-Sn-Ni catalysts. These catalysts were prepared by alcohol reduction. Nano-particles with diameters between 2.5-5.0 nm were obtained. The peak of (220) crystalline face centred cubic (fcc) Pt phase for PtSn and PtSnNi alloys was repositioned due to the presence of Sn and/or Ni in the alloy. Furthermore, the modification of Pt with Sn and SnNi improved ethanol and CO electro-oxidation. Copyright © 2016 BCREC GROUP. All rights reserved Received: 10th November 2015; Revised: 1st February 2016; Accepted: 1st February 2016 How to Cite: Hidayati, N., Scott, K. (2016). Electro-oxidation of Ethanol on Carbon Supported PtSn and PtSnNi Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1): 10-20. (doi:10.9767/bcrec.11.1.394.10-20) Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.394.10-2