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Archive for the ‘Hot Articles’ Category

Cleaner diesel engines – not just a pipe dream!

11 Apr 2013

Selective catalytic reduction (SCR) to date presents the most promising deNO_x technology for diesel engines. Removal of NO_x from diesel exhaust is problematic due to the wide temperature range (373–923 K) at which diesel engines operate. This is due to inefficient conversion at low temperature (below 423 K) with the commonly used ionic exchanged zeolites or low selectivity to N₂ with supported MnO_x catalysts.

In this HOT article, Tanaka et al. found that the temperature had a significant effect on the photocatalytic reactions in the gas phase over a TiO₂ photocatalyst with a maximum conversion of 84% (at GHSV 100,000 h^-1 and 433 K). The amount of NH₃ at high temperature was found to be key to a high NO conversion. The results provide evidence of the potential practicality of the use of photo-SCR for diesel engines.

Effects of reaction temperature on photocatalytic activity

Read more about these developments in photocatalysis by downloading the article now:

Effects of reaction temperature on the photocatalytic activity of photo-SCR of NO with NH₃ over a TiO₂ photocatalyst
Akira Yamamoto, Yuto Mizuno, Kentaro Teramura, Tetsuya Shishido and Tsunehiro Tanaka
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00022B

This article is part of a themed issue on photocatalysis that is due to be published later this year.

You may also be interested in a perspective recently published by the same author on the subject:

A unique photo-activation mechanism by “in situ doping” for photo-assisted selective NO reduction with ammonia over TiO₂ and photooxidation of alcohols over Nb₂O₅
Tetsuya Shishido, Kentaro Teramura and Tsunehiro Tanaka
Catal. Sci. Technol., 2011, 1, 541-551
DOI: 10.1039/C1CY00104C, Perspective

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Improving photocatalytic properties of titanium oxide with a new doping method

03 Apr 2013

TiO₂ nanotubes demonstrate photocatalytic properties that make them useful in applications such as decomposition of organic pollutants. These nanotubes are commonly grown in an anodization process that takes place in an electrolytic bath, with dopants, which are used to modify the catalytic properties of the nanotubes, added at a later stage.

In this paper, Hahn and co-workers have demonstrated a new growth method in which the desired dopants are dissolved in the electrolyte solution. The nanotubes grown from this solution incorporate the dopants, and no further treatment is required. A test of the photocatalytic properties of the nanotubes also confirms that it behaves very similar to nanotubes grown by conventional methods. This fast and convenient way of manufacturing doped TiO₂ nanotubes opens the route to many potential future applications.

Find out more by reading the full article:

Photocatalytic properties of in situ doped TiO₂-nanotubes grown by rapid breakdown anodization
Robert Hahn, Martin Stark, Manuela Sonja Killian and Patrik Schmuki
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00021D

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Metal oxide films as water oxidation catalysts

02 Apr 2013

Since hydrogen represents an alternative energy source to carbon-based fuel, there is a need to be able to split water using water oxidation catalysts (WOC) preferably by renewable energy sources such as sunlight. In this HOT article, the Spiccia group present a facile preparation of NiO_x films for use as WOC. These WOC films, deposited from macrocyclic Ni complexes in alkaline solution, were significantly more catalytically active at higher pH (12.9), therefore widening the range of conditions over which they can be deposited. Enhanced catalytic activity was also observed in visible light, indicating the films are electrochromic.

To learn more about these catalytic metal oxide films download the full paper now:

Anodic deposition of NiO_x water oxidation catalysts from macrocyclic nickel(II) complexes
Archana Singh, Shery L. Y. Chang, Rosalie K. Hocking, Udo Bach and Leone Spiccia
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00017F

This article is part of a themed issue on photocatalysis that is due to be published later this year.

You may also be interested in:
Highly active nickel oxide water oxidation catalysts deposited from molecular complexes
Archana Singh, Shery L. Y. Chang, Rosalie K. Hocking, Udo Bach and Leone Spiccia
Energy Environ. Sci., 2013, 6, 579-586
DOI: 10.1039/C2EE23862D

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Alkene hydration breaks the rules

22 Mar 2013

Alkene hydration (the addition of water to a carbon double bond) is an important industrial process for the direct synthesis of alcohols, widely used as chemical intermediates for resins, agricultural chemicals, surfactants, etc. In an extension of their previous work which involved selective aromatic ring hydroxylation by water with a platinum-loaded titanium oxide photocatalyst, the Yoshida Group, applied this photocatalytic system to alkene hydration.

Hydration of alkenes followed the anti-Markovnikov rule

The Pt–TiO₂ photocatalyst efficiently promoted anti-Markovnikov hydration of various alkenes with high selectivity. A possible reaction mechanism is also discussed in detail based on experiment and molecular orbital calculations. The results should prove useful for designing novel photocatalysts for selective organic transformations.

Read more about these developments in photocatalytic research by downloading the full article now:

Anti-Markovnikov hydration of alkenes over platinum-loaded titanium oxide photocatalyst
Hayato Yuzawa, Shoko Yoneyama, Akihito Yamamoto, Masanori Aoki, Kazuko Otake, Hideaki Itoh and Hisao Yoshida
Catal. Sci. Technol., 2013, DOI: 10.1039/C3CY00019B

This article is part of a themed issue on photocatalysis that is due to be published later this year.

Also, check out the previous paper which sparked this research:

Photocatalytic hydroxylation of aromatic ring by using water as an oxidant
Hisao Yoshida, Hayato Yuzawa, Masanori Aoki, Kazuko Otake, Hideaki Itoh and Tadashi Hattori
Chem. Commun., 2008, 4634-4636
DOI: 10.1039/B811555A

And the latest work by this group:

Heterogeneous palladium catalyst hybridised with titanium oxide photocatalyst for direct C–C bond formation between aromatic ring and acetonitrile
Hisao Yoshida, Yuki Fujimura, Hayato Yuzawa, Jun Kumagai and Tomoko Yoshida
Chem. Commun., 2013, Accepted Manuscript
DOI: 10.1039/C3CC41068D

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Improving conversion efficiency with Ga in solar cells

08 Mar 2013

Shigeru Ikeda and colleagues from Osaka University, Japan, have evidenced the ease and effectiveness of using spray pyrolysis to make CuInS₂-based solar cells in this HOT Catalysis Science & Technology paper. The effect of Ga-doping on structural properties related to photovoltaic and photoelectrochemical properties were investigated. Download the manuscript today to find out more…

Fabrication of CuInS₂ and Cu(In,Ga)S₂ thin films by a facile spray pyrolysis and their photovoltaic and photoelectrochemical properties
Shigeru Ikeda, Midori Nonogaki, Wilman Septina, Gunawan Gunawan, Takashi Harada and Michio Matsumura
Catal. Sci. Technol., 2013
DOI: 10.1039/C3CY00020F

This article is part of a themed issue on photocatalysis that is due to be published later this year.

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Industrial-scale enzyme catalysis a step closer

20 Feb 2013

Many biocatalysts require expensive co-factors when they are used in the production of industrially relevant compounds, but a team of UK chemists has replaced one such co-factor – nicotinamide adenine dinucleotide phosphate (NADPH) – with a smaller, more practical molecule: methyl viologen.

The production of cyclohexanone has been successfully catalysed using this method, combining methyl viologen with a biocatalyst enzyme in an electrochemical microfluidic set-up.

The work, published in Catalysis Science & Technology, represents the first time such enzyme-catalysed chemistry has been carried out without a co-factor, and presents a practical and economic route to its use in large-scale synthesis.

Read the article…

Electro-enzymatic viologen-mediated substrate reduction using pentaerythritol tetranitrate reductase and a parallel, segmented fluid flow system
Karl Fisher, Stephan Mohr, David Mansell, Nicholas J. Goddard, Peter R. Fielden and Nigel S. Scrutton

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Catalysts losing their nobility

13 Feb 2013

The emission of volatile organic compounds (VOCs) has has been a HOT topic in recent years due to their notorious implication in ozone layer depletion and the formation of ground level ozone. A specific type of VOC, Polycyclic Aromatic Hydrocarbons (PAHs) are also known to be carcinogenic. Catalytic oxidation has been utilised as one of the most effective ways to remove unwanted contaminants such as these, however, this usually involves expensive noble metals. In a move towards alternative materials such as metal-oxides, highly-active CeO₂ has recently been applied to reactions such as the above, CO oxidation and soot combustion – however, their widespread uptake by industry has been restricted by their poor thermal stability.

High thermal stability of ceria-based mixed oxide catalysts supported on zirconia for toluene combustion

Chen et al. have developed a simple, inexpensive and effective solution to the thermal stability problem, by loading mixed CeO₂-based oxides on ZrO₂. The catalytic combustion of toluene was studied and the ZrO₂ carrier was shown to not only to stabilise the surface active structure of the catalyst but also to improve its efficiency by enhancing O₂ mobility.

Read more about the potential of these catalysts by downloading the full article for FREE at:

High thermal stability of ceria-based mixed oxide catalysts supported on ZrO₂ for toluene combustion
Han-Feng Lu, Ying Zhou, Wen-Feng Han, Hai-Feng Huang and Yin-Fei Chen
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY20754D

You may also be interested in a related article:

High activity mesoporous copper doped cerium oxide catalysts for the total oxidation of polyaromatic hydrocarbon pollutants
Asunción Aranda, Elvira Aylón, Benjamín Solsona, Ramón Murillo, Ana María Mastral, David R. Sellick, Said Agouram, Tomás García and Stuart H. Taylor
Chem. Commun., 2012, 48, 4704–4706
DOI: 10.1039/C2CC31206A

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Nano gold boosts the Ullmann reaction

07 Feb 2013

Researchers from the Indian Institute of Chemical Technology have extended the repertoire of C-C bond forming reactions catalysed by gold nanoparticles to include that of the Ullmann reaction.

The Ullmann reaction is an old favourite for synthesising biaryls – it proceeds by coupling together two aryl halides using a transition metal catalyst (traditionally copper).

The heterogeneous catalytic system employed by the authors makes use of gold nanoparticles stabilised on commercially-available nanocrystalline magnesium oxide.

Read more about this work by downloading the article now:

Ullmann coupling of aryl iodides catalyzed by gold nanoparticles stabilized on nanocrystalline magnesium oxide
Keya Layek, H. Maheswaran and M. Lakshmi Kantam

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Copper NHCs in catalysis

21 Jan 2013

The first N-heterocyclic carbene-ligated coppper complex was made in the 90’s and no more than a decade later, their potential as catalysts was uncovered. As the number of Cu NHC complexes continues to grow, so does the number of catalytic possibilities.

In their Catalysis Science & Technology Mini Review, Researchers, Egbert, Cazin and Nolan from the University of St Andrews have outlined the reactions which benefit from this neat little complex; from hydrosilylations to allylic substitutions and click chemistry.

Download the article now…

Copper N-heterocyclic carbene complexes in catalysis
Jonathan D. Egbert, Catherine S. J. Cazin and Steven P. Nolan

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Nanoreactors for efficient oxidation

20 Dec 2012

Burri and co-workers describe the synthesis and application of new efficient mesoporous PdO/SBA-15 catalysts in this HOT article.

Oxidation of cyclohexene to cyclohexanone

The catalysts were reported to have a conversion and selectivity near 100% for the oxidation of cyclohexene to cyclohexenone. This high efficiency was attributed to the close contact with the reactive PdO nanoparticles as the reactants pass through the nanopores of the catalysts which thus may be considered as nanoreactors.

You can read more for FREE about these efficient oxidation nanoreactors at:

Highly efficient and expeditious PdO/SBA-15 catalysts for allylic oxidation of cyclohexene to cyclohexenone
Saidulu Ganji, Padma Bukya, Venkateswarlu Vakati, Kamaraju Seetha Rama Rao and David Raju Burri
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C2CY20627G, Communication

You may also be interested in other catalysis articles by the same author:

A magnetically recoverable γ-Fe₂O₃ nanocatalyst for the synthesis of 2-phenylquinazolines under solvent-free conditions
Narani Anand, Kannapu Hari Prasad Reddy, Tirumalasetty Satyanarayana, Kamaraju Seetha Rama Rao and David Raju Burri
Catal. Sci. Technol., 2012, 2, 570-574
DOI: 10.1039/C1CY00341K, Paper

Highly active Cu/MgO catalysts for selective dehydrogenation of benzyl alcohol into benzaldehyde using neither O₂ nor H₂ acceptor
Ravi Kumar Marella, Chinna Krishna Prasad Neeli, Seetha Rama Rao Kamaraju and David Raju Burri
Catal. Sci. Technol., 2012, 2, 1833-1838
DOI: 10.1039/C2CY20222K, Communication

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