Archive for the ‘Homogeneous catalysis’ Category

8th International Symposium on Carbon for Catalysis, CarboCat–VIII

The Carbon Group of the Portuguese Chemical Society (C@SPQ) cordially invites you to attend the 8th International Symposium on Carbon for Catalysis, CarboCat–VIII, that will take place in Porto, Portugal, on June 26 – 29, 2018.

Following the previous CarboCat meetings held in Lausanne (2004), Saint-Petersburg (2006), Berlin (2008), Dalian (2010), Brixen (2012), Trondheim (2014) and Strasbourg (2016), CarboCat-VIII will be devoted to new developments and fundamental advances on carbon materials (conventional and nanostructured carbons) for catalytic applications.

Catalysis Science & Technology together with Energy & Environmental Science, Materials Horizons and Journal of Materials Chemistry A are delighted to be supporting the event.

Register now!

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FineCat 2017: Great symposium at Royal Palace

Jointly organized by Italy’s Research Council and Palermo’s University, the 6th edition of the “FineCat – Symposium on heterogeneous catalysis for fine chemicals” was held in Sicily’s Royal Palace in Palermo on April 5th.

Gideon Grader at FineCat017 (Palermo, 5 April 2017)The scientific works (watch the video) were opened by Professor Gideon Grader, a Professor of chemical engineering at Haifa’s Technion where he leads the University’s energy program.

In an inspirational lecture Professor Grader discussed the mechanisms discovered by his group to create the unique mesoporous core-shell architecture of nanostructured materials with multifunctional, specific properties – an highly desirable finding which facilitates new possibilities and applications in all fields of catalysis due to the combination of high surface to volume ratio and low mass transfer resistance to and from the catalytic sites.

Heidelberg University’s organic chemistry Professor A. Stephen K. Hashmi, gave a fascinating lecture on new aspects of gold catalysis applied to the synthesis of a variety of functional products. Professor Hashmi described the latest findings concerning the new synthetic methods to access both gold(I) and gold(III) catalytic species, the identification of highly reactive catalysts, and the development of gold-catalyzed reactions including additions to allenes and alkenes, benzannulations, cycloisomerization, rearrangement as well as oxidation and reduction reactions.

Already used for the production of bulk chemicals, gold catalysis is poised to be introduced in the production of the basic ingredients of a wide variety of valued added products ranging from pharmaceuticals through liquid crystals and organic light emitting diodes (OLED) for computer, TV and mobile phone screens.

Raed Abu-REziq at FineCat017 (Palermo, 5 April 2017)Professor Raed Abu-Reziq, of the Hebrew University of Jerusalem, Israel, presented the results of his team concerning the development of new nanostructured materials, nano- and microreactors as platforms for heterogeneous catalysis. He showed how advanced sol-gel processing nanochemistry can be used to encapsulate, for example, ionic liquids and convert them from liquid to solid state.

Catalytic microreactors, he explained, have a potential to bridge between homogeneous and heterogeneous catalysis by the microencapsulation of catalyst dissolved or dispersed in non-volatile phase such as a ionic liquid.

Francesco Parrino, a post-doctoral researcher in the Schiavello-Grillone research group of Palermo’s University, presented the new results obtained in photocatalytic bromine synthesis. An eco-friendly and economic process capable to replace current industrial production via oxidation of bromide ions using gaseous chlorine is highly desirable, he explained opening his presentation.

Giuseppe Bagnato, a PhD student at Heriot-Watt University, United Kingdom, presented posters in the field of catalytic membrane reactor technology which he is now working to integrate in biorefinery.

His poster entitled “Hydrogenation of Bio-Oil: A Thermodynamic Study ” was awarded the best poster presentation prize – an online subscription to Catalysis Science & Technology, the RSC flagship catalysis journal with which the organisers of FineCat have partnered since the first edition of the Symposium in 2012.

Giuseppe was presented with a certificate signed by the journal’s Executive Editor, Dr Anna Simpson.

A full report of the conference proceedings can be found here.

The 7th edition of FineCat will be held in Sicily on 8th April 2018.

 

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15th National Youth Catalysis Conference – China

Catalysis Science & Technology is proud to announce that it awarded poster prizes at the 15th National Youth Catalysis Conference, “Multidisciplinary and multi-scale catalytic science and technology”, in China. The conference was held on 19th July 2015, at the University of Science and Technology of China (USTC), in Hefei. Plenary lectures were given by Professor Qingbai Xu (Tsinghua University), Professor Ye Wang (Xiamen University), Professor Wenjie Shen (Dalian Insitute of Chemical Physics, CAS), Professor Jiaguo Yu (Wuhan University of Technology) and Professor Baoning Zong (SINOPEC research institute of petroleum processing). Professors Wang, Shen and Yu are pictured below (left-right), together with the prize winners, Professor Weixin Huang (USTC, the local Chair) and Catalysis Science & Technology Associate Editor, Professor Ding Ma (Peking University).

The Winners:

Di Xin (Dalian University of Technolgy)

Ding Liangbing (University of Science and Technology of China)

Song Xiaojing   (Jilin University)

Han Lupeng (East China Normal University)

Su Xiaojuan (Ningxia University)

Chen Lang (Hunan University)

Su Diefeng (Zhejing University)

Wei Mingming (Dalian Institute of Chemical Physics, CAS)

Wang Dandan   (Xiamen University)

Gu Jing (Nanjing University)

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Nature leads the way: A Biomimetic Tricopper complex as a catalyst for selective oxidation of smaller alkanes

2014 has arrived and with it a new batches of Hot Articles, one of which from January deserves special attention. Professor Sunny Chan‘s group at Academia Sinica,  Taiwan have achieved the distinction of being the first group to devise a molecular catalyst for the selective oxidation of methane to methanol. This reaction faces a formidable challenge in the form of inertness of the methane C–H bond which makes O-atom insertion into the molecule almost impossible in ambient conditions.  Even if this problem is solved, the product, methanol, is highly susceptible to over-oxidation leading to formation of other undesired products. For of these reasons, most of the researchers have failed to scale this gargantuan mountain of difficulties.

Time and again when scientists have found it difficult to get answers to tough and challenging problems they have turned to nature for inspiration. In this case, the solution lay in a particular class of enzymes called methane monoxygenases (MMO) found in the methanotrophic bacteria. These MMOs have metallic clusters at their centres, which catalyse this difficult reaction with ease. In order to emulate these catalytic centres, the researchers developed some biomimetic models containing tricopper clusters, one of which, [CuICuICuI(7-N-Etppz)][ClO4], successfully mediated the selective oxidation of methane without any over-oxidation. This tricopper complex, when activated by dioxygen (O2), harnesses a “singlet oxene”, the strongest oxidant that could be used for a facile O-atom insertion across the C-H bond.

Biomimetic Tricopper complex as a catalyst for selective oxidation of methane to methanol

The catalyst also gave selectivity in the cases of ethane and propane, but not with higher alkanes. The reason being is the design of the tricopper catalyst, which has a small hydrophobic binding pocket at the base and forms a transient complex with the alkane and carries out the oxene transfer to oxidize the substrate. This pocket is not big enough to accommodate the product methanol (as well as the other small alcohols), so it releases the product as soon as it is formed. This removes over-oxidation from the equation, giving profound selectivity in cases of smaller alkanes. The authors have further studied the catalytic cycles and analysed the factors affecting the catalytic turnovers and efficiency.

This work presents a move towards a more efficient flow system which, in the future, would help in increasing the yields of the products. One issue with the current system is the solubility of the catalyst in solvents which can dissolve CH4 gas which may be put to rest by some modification in the design of the catalyst, leaving brighter prospects for the future.

To find out more about this nature-inspired discovery, read the full article now for more details.

Developing an efficient catalyst for controlled oxidation of small alkanes under ambient conditions
Penumaka Nagababu, Steve S.-F. Yu, Suman Maji, Ravirala Ramu and Sunney I. Chan
Catal. Sci. Technol., 2014, DOI: 10.1039/C3CY00884C


Shreesha Bhat, Web Writer Shreesha Bhat is a M.S.(Pharm.) in Medicinal Chemistry from National Institute  of  Pharmaceutical Education and Research,  India. He has recently joined the research group of  Dr. Pallavi Sharma as a PhD student at the  University of Lincoln, UK. His project involves  the design and synthesis of Helicase-primase inhibitors for Herpes Simplex virus and development of useful synthetic methodologies.

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Doubts put to rest: On a Quest for the real intermediates in Iron based Water Oxidation at low pH

It gives an absolute delight to the grey matter to imagine power generated from simple tap water. Power which could be supplied to our home and cars and thus put an end to the incessant use of fossil fuels. Yes friends, after the Bronze and Iron age, now it’s time for the Hydrogen age. The term “Hydrogen Economy” is gaining momentum and has the potential to do for the energy revolution what the computer and the Internet have done for the information revolution.

Among the various methods available for hydrogen production, water-splitting is one of the most promising approaches. Earlier, water oxidation catalysis have been performed efficiently with expensive, toxic and earth-scarce transition metals, but 3d metal-based catalysts are much less established. Fillol and Costas in their Nature Chemistry paper explored the use of environmentally benign and easily available iron coordination complexes for water oxidation with evident success. Their observation suggested that the iron complexes, when combined with Ce(IV) gets decomposed to iron oxides, which are, in fact, the main active catalysts for the water oxidation.

Substantial work by Tai-Chu Lau and group indicated that the actual catalysts for water oxidation are different at low and high pH values. It has been confirmed through various studies that at high pH, Fe2O3 is indeed the active metal catalyst, but researchers are still mystified as to what would be the intermediate at low pH. It has been speculated that the water oxidation at low pH goes through a molecular oxo-Fe active intermediate, as no evidence for Fe oxide formation has been obtained till date. The reason for this was given by Fillol and Costas, who proved that Fe (III) does not oxidize water in acidic conditions nor does it convert to Fe oxide. Another possibility that has been looming in the minds of the scientists is that FeO42- ions being strong oxidants can oxidize water in acidic conditions. But, scientists have shown that Ce(IV) is not capable of oxidizing Fe(III) to  FeO42. So, It has been a matter of debate as to which is the real catalyst for low pH water oxidation: Is it FeO42- indeed? Or an oxo-Fe intermediate?

Water oxidation by iron complexes in presence of Ce(IV)

In this communication, a group of Iranian scientists have tried to answer this question and included it in their quest for a more effective iron-based water oxidation catalyst. Their work has substantial basis in the work done by Fillol and Costas whose one observation was the inability of Fe(III) oxohydroxo 2µ-(O,OH) diferric dimer to catalyze water oxidation. So, a question was posed by Mohammad Mahdi Najafpour and group if an Fe(III) complex with only one bridge (oxo {O} or hydroxo {OH}) can be a water oxidizing catalyst? And if FeO42- has any role in the whole process?

To answer the above two important questions, they synthesized an Fe(III) oxo diferric dimer with tris(2-pyridylmethyl)amine (tpa) ligand with only one µ-O bridge, and tested the dimer for water oxidation in presence of  Ce(IV), and found it to be 6 times more active (measured in terms of TOF)  than the monomer reported by Fillol, Costas and workers. This provided a new insight into the mechanism, suggesting that a monomer might be just a precursor to the active catalyst which might be a di- or a multinuclear iron compound. The experiments prove that even if Fe ions convert to FeO42- in the presence Ce(IV), FeO42- cannot oxidize water catalytically, thus putting an end to the long lasting debate of FeO42- being an intermediate in these reactions.

Read more at:

A dinuclear iron complex with a single oxo bridge as an efficient water-oxidizing catalyst in the presence of cerium (IV) ammonium nitrate: New findings and current controversies
Mohammad Mahdi Najafpour, Atefeh Nemati Moghaddam, Davood Jafarian Sedigh and Malgorzata Holynska
Catal. Sci. Technol.,2013, Accepted Manuscript
DOI:
10.1039/C3CY00644A


Shreesha Bhat, Web Writer Shreesha Bhat is a M.S.(Pharm.) in Medicinal Chemistry from National Institute  of  Pharmaceutical Education and Research,  India. He has recently joined the research group of Dr. Pallavi Sharma as a PhD student at the  University of Lincoln, UK. His area of interests  include  chemical  synthesis of biologically important molecules  and developing newer methods for organic synthesis using novel catalysts.

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Tannins help in biphasic catalysis

There are pros and cons to both homogeneous and heterogeneous catalytic strategies. One way to get the best of both worlds is to use aqueous-organic biphasic catalysis. This approach hasn’t been widely utilised so far due to interfacial resistance between the phases which causes a low catalytic activity.

Researchers in China have overcome this by using tannins from Black Wattle (an acacia tree species). The tannins “amphiphilicly” stabilise catalytic palladium nanoparticles enabling them to catalyse reactions in the organic phase whilst remaining in the aqueous phase for subsequent re-use, without loss of activity.

Read the full article here:

Using plant tannin as natural amphiphilic stabilizer to construct aqueous-organic biphasic system for highly active and selective hydrogenation of quinoline
Hui Mao, Jun Ma, Yang Liao, Shilin Zhao and Xuepin Liao
Catal. Sci. Technol., 2013, DOI:10.1039/C3CY00108C

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Copper NHCs in catalysis

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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Olefin epoxidation – which catalyst to choose?

Simone Hauser, Mirza Cokoja and Fritz Kühn explore recent developments in homogeneous epoxidation catalysts in this hot Catalysis Science & Technology Perspective.  They look at the different catalysts used for different olefins as well as thinking about the context in which the catalysts would be used.

The manuscript is currently free so download it now, it might help you decide which catalyst to use….

Epoxidation of olefins with homogeneous catalysts – quo vadis?
Simone A. Hauser, Mirza Cokoja and Fritz E. Kühn
Catal. Sci. Technol., 2013
DOI: 10.1039/C2CY20595E

The epoxidation of olefins catalyzed by molecular transition metal compounds is a research field, which has been extensively studied over the past forty years.

Other Catalysis Science & Technology articles by the same author are:

Xylyltrioxorhenium – the first arylrhenium(VII) oxide applicable as an olefin epoxidation catalyst

Stefan Huber, Mirza Cokoja, Markus Drees, János Mínk and Fritz E. Kühn
Catal. Sci. Technol., 2013
DOI: 10.1039/C2CY20371E, Paper

PtO2 as a “self-dosing” hydrosilylation catalyst
Sophie Putzien, Eckhart Louis, Oskar Nuyken and Fritz E. Kühn
Catal. Sci. Technol., 2012, 2, 725-729
DOI: 10.1039/C2CY00367H

Methyltrioxorhenium-catalysed oxidation of pseudocumene in the presence of amphiphiles for the synthesis of vitamin E
Mónica Carril, Philipp Altmann, Werner Bonrath, Thomas Netscher, Jan Schütz and Fritz E. Kühn
Catal. Sci. Technol., 2012, 2, 722-724
DOI: 10.1039/C1CY00313E

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Hydroformylation for the higher alkenes

Hydroformylation (or the oxo process) is an important industrial procedure which combines alkenes with carbon monoxide and hydrogen to produce aldehydes, which are easily hydrogenated to alcohols and then plasticizers or detergents. Hydroformylation is used to produce around 9 million tons of aldehyde per year world-wide and is one of the largest industrial applications of homogeneous catalysis.

Alternative approaches for the aqueous–organic biphasic hydroformylation of higher alkenes

Catalyst recycling is highly desirable to reduce costs and was effectively implemented for short chain alkenes with the development of the aqueous biphasic Ruhrchemie/Rhone-Poulenc (RCH/RP) process, however due to mass-transfer limitations the application of this process is constrained to the short chain hydrocarbons. This Hot Perspective by Lorenz Obrecht, Paul C. J. Kamer and Wouter Laan details some of the alternative approaches which have been developed for the aqueous–organic biphasic hydroformylation for higher alkenes.

Alternative approaches for the aqueous–organic biphasic hydroformylation of higher alkenes
Lorenz Obrecht, Paul C. J. Kamer and Wouter Laan
Catal. Sci. Technol., 2013, Advance Article

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Catalysis in industry themed issue now online

This month’s Catalysis Science & Technology issue is the devoted to Homogeneous and Heterogeneous Catalysis in Industry.

The themed issue which is guest edited by Professors Hans de Vries (DSM and University of Groningen) and David Jackson (University of Glasgow) comprises a selection of articles that illustrate the research necessary for moving a reaction off the lab bench and into the industrial plant. Unsurprisingly, catalytic research is often key to this journey.

Catalysis in industry front coverSelect the links below to read the Editorial and review articles. The full issue can be accessed here.

Editorial
Homogeneous and Heterogeneous Catalysis in Industry; Johannes G. de Vries and S. David Jackson

Perspective
First-principles kinetic modeling in heterogeneous catalysis: an industrial perspective on best-practice, gaps and needs; Maarten K. Sabbe, Marie-Françoise Reyniers and Karsten Reuter

Mini Review
Advances in conversion of hemicellulosic biomass to furfural and upgrading to biofuels; Saikat Dutta, Sudipta De, Basudeb Saha and Md. Imteyaz Alam

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