Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production

and Perspectives Sophie Carenco,†,‡,§,∥,⊥ David Portehault,*,†,‡,§ Ced́ric Boissier̀e,†,‡,§ Nicolas Meźailles, and Cleḿent Sanchez*,†,‡,§ †Chimie de la Matier̀e Condenseé de Paris, UPMC Univ Paris 06, UMR 7574, Colleg̀e de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France ‡Chimie de la Matier̀e Condenseé de Paris, CNRS, UMR 77574, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Chimie de la Matier̀e Condenseé de Paris, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Laboratory Heteroelements and Coordination, Chemistry Department, Ecole Polytechnique, CNRS-UMR 7653, Palaiseau, France

Nanoscaled metal borides and phosphides: recent developments and perspectives

Novel catalysts for advanced hydroprocessing: transition metal phosphides

Hydrogen evolution by means of electrocatalytic water-splitting is pivotal for efficient and economical production of hydrogen, which relies on the development of inexpensive, highly active catalysts. In addition to sulfides, the search for non-noble metal catalysts has been mainly directed at phosphides due to the superb activity of phosphides for hydrogen evolution reaction (HER) and their low-cost considering the abundance of the non-noble constituents of phosphides. Here, recent research focusing on phosphides is summarized based on their synthetic methodology. A comparative study of the catalytic activity of different phosphides towards HER is then conducted. The catalytic activity is evaluated by overpotentials at fixed current density, Tafel slope, turnover frequency, and the Gibbs free energy of hydrogen adsorption. Based on the methods discussed, perspectives for the various methods of phosphides synthesis are given, and the origins of the high activity and the role of phosphorus on the improved activity towards HER are discussed.

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A Review of Phosphide-Based Materials for Electrocatalytic Hydrogen Evolution

The gas phase hydrodeoxygenation (HDO) of guaiacol, as a model compound for pyrolysis oil, was tested on a series of novel hydroprocessing catalysts – transition metal phosphides which included Ni2P/SiO2, Fe2P/SiO2, MoP/SiO2, Co2P/SiO2 and WP/SiO2. The turnover frequency based on active sites titrated by the chemisorption of CO followed the order: Ni2P > Co2P > Fe2P, WP, MoP. The major products from hydrodeoxygenation of guaiacol for the most active phosphides were benzene and phenol, with a small amount of methoxybenzene formed. Kinetic studies revealed the formation of reaction intermediates such as catechol and cresol at short contact times. A commercial catalyst 5% Pd/Al2O3 was more active than the metal phosphides at lower contact time but produced only catechol. A commercial CoMoS/Al2O3 deactivated quickly and showed little activity for the HDO of guaiacol at these conditions. Thus, transition metal phosphides are promising materials for catalytic HDO of biofuels.

Hydrodeoxygenation of guaiacol as model compound for pyrolysis oil on transition metal phosphide hydroprocessing catalysts

Ozone decomposition was investigated under reaction conditions by using Raman spectroscopy on a supported manganese oxide catalyst. An adsorbed species with a Raman signal at 884 cm-1 was observed during reaction, and was identified as a peroxide species by a combination of in situ Raman spectroscopy and 18O isotopic substitution measurements. The observed isotope shift ν(18O)/ν(16O) value of this adsorbed species was 0.946, in excellent agreement with the ratio calculated for a peroxide species (0.943) by using a harmonic oscillator model. Ab initio molecular orbital calculations confirmed this assignment, using Mn(OH)4(O2)+ as a model compound for the adsorbed species. The reaction mechanism of ozone decomposition was elucidated with carefully designed experiments, including isotopic substitution. The reaction sequence involved dissociative adsorption of ozone to form an oxygen molecule and an atomic oxygen species, reaction of the atomic species with gaseous ozone to form an adsorbed peroxide species a...

Mechanism of Ozone Decomposition on a Manganese Oxide Catalyst. 1. In Situ Raman Spectroscopy and Ab Initio Molecular Orbital Calculations

Synthesis and Activity of a New Catalyst for Hydroprocessing: Tungsten Phosphide

A single phase molybdenum phosphide, MoP, with a moderate surface area was prepared using temperature programmed reduction of an amorphous phosphate precursor and the so-prepared sample was found to be a good catalyst for hydrodenitrogenation.

Molybdenum Phosphide: A Novel Catalyst for Hydrodenitrogenation

This paper presents a general methodology to determine reaction mechanisms using in situ measurement of concentration and reaction rate of intermediates. The criteria for testing the validity of a reaction sequence are discussed. An example is given for a heterogeneous catalytic reaction, the decomposition of ozone on manganese oxide.

Absolute determination of reaction mechanisms by in situ measurements of reaction intermediates

Publisher Summary Ethanol was found to react with ozone at lower temperatures than with oxygen and also with lower activation energy. This is in agreement with the stronger oxidizing ability of ozone compared to oxygen. In situ laser Raman spectroscopic studies showed the existence of adsorbed ethoxide species on the catalyst surface under reaction conditions; however, at a much lower concentration than when oxygen alone was used as the oxidant. Ozone was generally found to be effective at enhancing the conversion of VOCs, especially at low temperatures. The kinetics of complete oxidation of benzene by ozone on MnO 2 was investigated. It was concluded that the rate determining step for benzene oxidation by ozone was ozone decomposition. The oxidation of lower aliphatic alcohols by ozone over silica and alumina has been studied. It was also found that the main products of the oxidation reactions were acetaldehyde and carbon dioxide from ethanol, propionaldehyde and carbon dioxide from n -propanol, and acetone from isopropanol. Alumina and silica supported MnO 2 catalysts were prepared by incipient wetness impregnation of supports, using manganese acetate, as the precursor and were calcined in air at 773 K for 3 h prior to use. The crystal phases of MnO 2 in the catalysts were identified, using X-ray diffraction (XRD), and their surface areas were determined by N 2 physisorption, using the Brunauer, Emmett, and Teller (BET) method.

Wei Li

Papers

Mechanism of Ozone Decomposition on a Manganese Oxide Catalyst. 1. In Situ Raman Spectroscopy and Ab Initio Molecular Orbital Calculations

Synthesis and Activity of a New Catalyst for Hydroprocessing: Tungsten Phosphide

Molybdenum Phosphide: A Novel Catalyst for Hydrodenitrogenation

Absolute determination of reaction mechanisms by in situ measurements of reaction intermediates

Ethanol oxidation using ozone over supported maganese oxide catalysts: An in situ laser raman study