Catalysis Science & Technology Blog

Epoxides are used in the production of a wide range of compounds including resins, perfumes and polyethers among many others. The commercial synthesis of epoxides uses olefins, either through the chlorohydrin process or the hydroperoxide process. This Hot Article from Professor Bert Weckhuysen et al. details a mechanistic study on cyclohexene epoxidation with cyclohexyl hydroperoxide, the team performed the reaction over titanium grafted mesoporous silica.

Two competing reactions appear to occur, one producing the epoxide and the other yielding
cyclohexanone. As all articles are free to access in Catalysis Science & Technology for the duration of 2012 you can download this article now to see the proposed mechanistic pathways.

Mechanistic insights in the olefin epoxidation with cyclohexyl hydroperoxide
Bart P. C. Hereijgers, Rudy F. Parton and Bert M. Weckhuysen
Catal. Sci. Technol., 2012, Advance Article
DOI: 10.1039/C2CY00455K, Paper

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Catalytic hydrogen transfer (CTH) reactions have been around for a while and provide an alternative to traditional hydrogenation, where H₂ gas is applied under high pressure. Hydrogen donors include alcohols or formate salts while acceptors are unsaturated organic compounds, ketones, olefins and nitroaromatics among others. Ruthenium complexes are some of the most active homogeneous catalysts for CTH and a wide range have been developed over the last 40 years.

This Hot Article from Judith Toubiana and Yoel Sasson (The Hebrew University of Jerusalem) details their investigation into the mechanism of CTH between alcohols and ketones using RuCl₂(PPh₃)₃, the pair have made a remarkable discovery regarding the actual active species in the reaction……and it isn’t the ruthenium complex.

As all Catalysis Science & Technology articles are free to access for the duration of 2012 you can download the paper now to find out what has been discovered and how.

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The true catalyst in hydrogen transfer reactions with alcohol donors in the presence of RuCl2(PPh3)3 is ruthenium(0) nanoparticles
Judith Toubiana and Yoel Sasson
Catal. Sci. Technol., 2012, Advance Article
DOI: 10.1039/C2CY00514J, Paper

As well as eutrophication, excess nitrates in water can also cause serious side-effects in humans including increased rates of cancer and blue-baby disease. Legislation dictates the amount of nitrate that agricultural waste water can contain, specifically 50, 0.1 and 0.5 ppm for NO₃, NO₂ and NH₄⁺, respectively. The need to treat water to remove nitrates is an important challenge for catalysis.

This Hot Article from Jacinto Sa and Noelia Barrabe et al. investigates nitrate reduction using the bimetallic catalysts Pt–Cu and Pd–Cu. The team were able to use in situ high-energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy (XAS) to study the oxidation state of copper, which is in a redox cycle with hydrogen and the unwanted nitrates.

As all articles in Catalysis Science & Technology are free to access for the duration of 2012, you can look at the teams results in more detail by downloading their hot article.

The oxidation state of copper in bimetallic (Pt–Cu, Pd–Cu) catalysts during water denitration
Jacinto Sá, Noelia Barrabés, Evgeny Kleymenov, Chen Lin, Karin Föttinger, Olga V. Safonova, Jakub Szlachetko, Jeroen A. van Bokhoven, Maarten Nachtegaal, Atsushi Urakawa, Gastón A. Crespo and Günther Rupprechter
Catal. Sci. Technol., 2012, Advance Article
DOI: 10.1039/C2CY00461E

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One of the obstacles in using H₂ as an energy source is generating H₂ gas and while the photocatalysis of water has been widely studied, catalysts which operate under visible light have been rather under-utilised.

Su Su Khine Ma, Kazuhiko Maeda and Kazunari Domen have developed a ZrO₂-modified tantalum oxynitride photocatalyst which operates at wavelengths > 420 nm and in their Hot article discuss a range of preparations using different Zr precursors under different conditions. All articles in Catalysis Science & Technology are free to access for the duration of 2012 so you can see full details of their investigation and the factors that affect H₂ evolution by downloading their full paper.

Modification of TaON with ZrO2 to improve photocatalytic hydrogen evolution activity under visible light: influence of preparation conditions on activity
Su Su Khine Ma, Kazuhiko Maeda and Kazunari Domen
Catal. Sci. Technol., 2012, Advance Article
DOI: 10.1039/C2CY00499B

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