Catalysis Science & Technology Blog

Simple and inexpensive method for highly efficient biodiesel production

Tien Nguyen, Guest Web-writer — Thu, 13 Jun 2013 13:49:11 +0000

According to the USDA foreign agriculture service, the European Union consumed 13.8 billion litres of biodiesel in 2012. The increasing demand for biodiesel stems from its lower greenhouse gas emissions, estimated to be 57% lower than emissions from burning petroleum diesel. To become competitive with fossil fuels, alternative energy sources must achieve low production costs starting from abundant feedstocks.

In this Advance Article, Yang and co-workers reports the transesterification of several oils to biodiesel (primarily fatty acid methyl ester, FAME), obtaining >97% yields using 3 wt% calcined porous calcite or dolomite catalysts. Prepared through simple thermal decomposition of cheap Mg/Ca carbonate minerals and stearic acid mixtures, these heterogeneous catalysts possess high special surface areas (SSAs) increasing the sites accessible for reactivity.

The researchers found that the catalysts could be regenerated by treatment with stearic acid, and re-used with no appreciable loss in activity. The authors propose that this process could be well-suited for industrial application as it is inexpensive and environmentally benign.

Read the full article here:

A facile, low-cost route for the preparation of calcined porous calcite and dolomite and their application as heterogeneous catalysts in biodiesel production

Rui Wang. Hu Li, Fei Chang, Jiafeng Luo, Milford A. Hanna, Daoyang Tan, Deyu Hu, Yuping Zhang, Baoan Song, and Song Yang

Catal. Sci. Technol., 2013, DOI:10.1039/C3CY00129F

Tien Nguyen is a web contributor working towards her PhD in David Nicewicz’s research group at the University of North Carolina at Chapel Hill, USA. Her current area of research focuses on anti-Markovnikov hydroamination of alkenes using photoredox catalysis.

Here comes the sun – visible light promoted MOF catalysts

Fiona McKenzie, Deputy Editor — Wed, 29 May 2013 08:04:01 +0000

Posted on behalf of Tien Nguyen

Tien Nguyen is working towards her PhD in David Nicewicz’s research group at the University of North Carolina at Chapel Hill, USA. Her current area of research focuses on anti-Markovnikov hydroamination of alkenes using photoredox catalysis.

To satisfy the energy demands of an ever-increasing population, it is critical to develop renewable energy sources. Photocatalytic hydrogen production from water stands out among the alternatives as this process yields a clean energy source and relies on visible light, which has exciting implications for harnessing the power of the sun.

In this article, Matsuoka and co-workers report efficient hydrogen production employing a Pt-deposited amino-functionalized Ti metal organic framework catalyst (Pt/Ti-MOF-NH₂) in aqueous triethanolamine (TEOA) and visible light. The organic linker serves to absorb the light and donate electrons to the titanium-oxo cluster with TEOA present as a sacrificial electron donor. An optimal loading of 1.5 wt% was found for the Pt cocatalyst, which is proposed to trap the photogenerated electrons and suppress unproductive electron-hole recombination.

The authors also successfully extended this system to the reduction of nitrobenzene, providing an environmentally benign alternative to existing methods. They found that the photocatalyst could be reused at least three times with no appreciable loss in activity. These findings hold promise for the development of highly efficient photocatalysts promoted by naturally abundant sunlight.

Read the full article here:

Efficient hydrogen production and photocatalytic reduction of nitrobenzene over a visible-light-responsive metal–organic framework photocatalyst
Takashi Toyao, Masakazu Saito, Yu Horiuchi, Katsunori Mochizuki, Masatoshi Iwata, Hideyuki Higashimura and Masaya Matsuoka

Catal. Sci. Technol., 2013, DOI: 10.1039/c3cy00211j

Foam, fleece and honeycomb supports for platinum nanoparticles

Sara Coles, Guest Web-Writer — Tue, 21 May 2013 08:21:56 +0000

Sara Coles is a guest web-writer for Catalysis Science & Technology. She
currently works for Johnson Matthey in Royston, UK.

Foam, fleece and honeycomb have one unexpected thing in common: they are all physical structures that can be made into supports for industrial platinum catalysts.

Patrick Sonström and colleagues in Germany have studied the deposition of colloidally preformed nanoparticles of platinum deposited with or without a washcoat onto low surface area codierite honeycombs, alumina foam and nickel fleece.

Their technique allows higher platinum loadings to be applied without the disadvantages of agglomeration and adhesion, meaning that higher catalytic activities can be achieved on low surface area substrates.

This could have potential to expand the use of monolithically supported platinum catalysts beyond their automotive niche and into wider industrial use for reactions such as methanol steam reforming, oxidative dehydrogenation of propane and liquid phase hydrogenations. The advantages of monolithic catalysts over their classic pellet bed alternatives include lower pressure drops and improved mass transfer.

To find out more about this work read the article in Catalysis Science & Technology:

Foam, fleece and honeycomb: catalytically active coatings from colloidally prepared nanoparticles
Patrick Sonström, Birte Halbach, Sonia Tambou Djakpou, Beate Ritz, Kirsten Ahrenstorf, Georg Grathwohl, Horst Weller and Marcus Bäumer

Catal. Sci. Technol., 2011, 1, 830–838, DOI: 10.1039/c1cy00077b

This one is “just right” – Nanoparticle size effects in CO methanation

Fiona McKenzie, Deputy Editor — Tue, 14 May 2013 12:14:27 +0000

Posted on behalf of Tien Nguyen, web-writer for Catalysis Science & Technology

On May 8^th 2013, the NOAA’s (National Oceanic & Atmospheric Administration) Mauna Loa observatory recorded a daily mean concentration of CO₂in excess of 400 ppm, a record high since mankind’s appearance on the planet. As carbon dioxide levels continue to increase at an alarming rate, many laboratories are engaging in alternative energy research to mitigate this problem.

One such solution involves the methanation reaction, which converts syngas (CO + H₂) to synthetic natural gas (CH₄). This reaction is highly sought after given that energy from burning natural gas releases approximately 30-45% less carbon dioxide than fossil fuels.

In this article, researchers evaluated a series of α-Al₂O₃-supported Ni catalysts of various Ni particle size (5-10, 10-20 and 20-35 nm) for their catalytic efficiency in the methanation reaction. At high temperatures (300-600 °C), ambient pressure and high WHSV (weight hourly space velocity of 240,000 mL/g/h), Ni particles sized 10-20 nm exhibited the highest CO conversion, CH₄ yield and turnover frequency, as well as the lowest carbon deposition.

They hypothesized that the smaller Ni particles exhibit more carbon deposition because they have more exposed step edges, which are more susceptible to such formations. They also proposed that Ni particles that are too large may lead to the undesirable growth of carbon nanofibers. Having identified the optimal Ni particle size, the next advancement for the CO methanation reaction lies in improving the stability of these catalysts.

Read the article here:

Effect of nickel nanoparticle size in Ni/α-Al₂O₃ on CO methanation reaction for the production of synthetic natural gas
Jiajian Gao, Chunmiao Jia, Meiju Zhang, Fangna Gu, Guangwen Xua and Fabing Su

Cracking activity of Y zeolites depends on their Bronsted acidity

Wendy Mak, Development Editor — Wed, 08 May 2013 13:52:51 +0000

Alkane cracking is an important industrial process, and zeolites are commonly used as catalysts in the reaction. There have been many studies into the reaction, and the variation in the catalytic activity between different zeolites is often explained by the differences in the heat of alkane adsorption on the zeolite, which is determined by the pore size.

In this paper, the authors proposed that the zeolite acid strength (the BrØnsted acidity), rather than heat of alkane adsorption on the zeolite is the main factor in determining the cracking activity. They supported this view with a series of experiments and computational studies on ultra-stable Y zeolites. These include measurements of how the activation energy of cracking varies with the acidity of the zeolite, and a density functional theory calculation of the reaction. The good agreement between the model and experimental results suggests that the proposed mechanism is correct.

Find out more from their paper:

Dependence of cracking activity on the Brønsted acidity of Y zeolite: DFT study and experimental confirmation
Miki Niwa, Katsuki Suzuki, Nami Morishita, German Sastre, Kazu Okumura and Naonobu Katada
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00195D, Paper

Improving catalytic performance of (L)-proline with chiral additives

Wendy Mak, Development Editor — Wed, 08 May 2013 12:34:23 +0000

(L)-proline is a common organocatalyst used in synthetic reactions to produce chiral molecules as it is cheap and readily available. However, it is not very efficient, and there has been much interest in optimising its performance. One method is the modification of (L)-proline through a redesign and resynthesis, which can be quite complex. An easier alternative is to find additives that can improve the reaction in terms of yield and selectivity.

In this paper, the authors synthesised and investigated the effects of a chiral additive, enantiopure substituted imidazoles, on the (L)-proline-catalyzed aldol reaction. They found that it has greatly improved the selectivity of the reaction and the reaction rate. Addition studies of the reaction mechanism suggests that the supramolecular complex formed by the imidazole and (L)-proline helps to improve the efficiency of the catalyst. Further work on different co-catalysts can open up many more reactions in which (L)-proline can be used as an effective catalyst.

Read the paper and find out more.

Chemoenzymatic synthesis of optically active 2-(2′- or 4′-substituted-1H-imidazol-1-yl)cycloalkanols: chiral additives for (L)-proline
Raul Porcar, Nicolás Ríos-Lombardía, Eduardo Busto, Vicente Gotor-Fernández, Vicente Gotor, Eduardo Garcia-Verdugo, M. Isabel Burguete and Santiago V. Luis
Catal. Sci. Technol., 2013, Advance Article
DOI: 10.1039/C3CY00107E, Paper

Highly cited 2012 articles

Wendy Mak, Development Editor — Thu, 02 May 2013 12:46:08 +0000

The following is ten of the most cited articles published in Catalysis Science and Technology in 2012. Read what has been making an impact in the world of catalysis.

Graphene-based materials for catalysis
Bruno F. Machado and Philippe Serp
Catal. Sci. Technol., 2012, 2, 54-75
DOI: 10.1039/C1CY00361E

Recent advances in organocatalytic asymmetric Michael reactions
Yong Zhang and Wei Wang
Catal. Sci. Technol., 2012, 2, 42-53
DOI: 10.1039/C1CY00334H

Organocatalytic enantioselective methodologies using Morita–Baylis–Hillman carbonates and acetates
Ramon Rios
Catal. Sci. Technol., 2012, 2, 267-278
DOI: 10.1039/C1CY00387A

Ag nanoparticles decorated polyaniline nanofibers: synthesis, characterization, and applications toward catalytic reduction of 4-nitrophenol and electrochemical detection of H₂O₂ and glucose
Guohui Chang, Yonglan Luo, Wenbo Lu, Xiaoyun Qin, Abdullah M. Asiri, Abdulrahman O. Al-Youbi and Xuping Sun
Catal. Sci. Technol., 2012, 2, 800-806
DOI: 10.1039/C2CY00454B

Conversion of lignocellulose into renewable chemicals by heterogeneous catalysis
Hirokazu Kobayashi, Hidetoshi Ohta and Atsushi Fukuoka
Catal. Sci. Technol., 2012, 2, 869-883
DOI: 10.1039/C2CY00500J

Asymmetric catalysis using iron complexes – ‘Ruthenium Lite’?
Muftah Darwish and Martin Wills
Catal. Sci. Technol., 2012, 2, 243-255
DOI: 10.1039/C1CY00390A

Iron(III) metal–organic frameworks as solid Lewis acids for the isomerization of α-pinene oxide
Amarajothi Dhakshinamoorthy, Mercedes Alvaro, Hubert Chevreau, Patricia Horcajada, Thomas Devic, Christian Serre and Hermenegildo Garcia
Catal. Sci. Technol., 2012, 2, 324-330
DOI: 10.1039/C2CY00376G

Aerobic oxidation of 5-hydroxylmethylfurfural with homogeneous and nanoparticulate catalysts
Basudeb Saha, Saikat Dutta and Mahdi M. Abu-Omar
Catal. Sci. Technol., 2012, 2, 79-81
DOI: 10.1039/C1CY00321F

Speciation of Pd(OAc)₂ in ligandless Suzuki–Miyaura reactions
Luis A. Adrio, Bao N. Nguyen, Gemma Guilera, Andrew G. Livingston and King Kuok (Mimi) Hii
Catal. Sci. Technol., 2012,2, 316-323
DOI: 10.1039/C1CY00241D

Metal–organic frameworks for catalysis: the Knoevenagel reaction using zeolite imidazolate framework ZIF-9 as an efficient heterogeneous catalyst
Lien T. L. Nguyen, Ky K. A. Le, Hien X. Truong and Nam T. S. Phan
Catal. Sci. Technol., 2012,2, 521-528
DOI: 10.1039/C1CY00386K

A Green Cocktail for the Industrial Synthesis of Lactic acid

Fiona McKenzie, Deputy Editor — Tue, 30 Apr 2013 08:28:22 +0000

Posted on behalf of Shreesha Bhat

Lactic acid is a versatile chemical having wide applications in food, cosmetics and chemical industry. They are generally prepared by acid catalyzed reactions of hexoses and trioses, and one such triose i.e. glycerol has been found to be produced in surplus amounts as byproducts in production of biodiesel. Glycerol offers great potential to be used as a renewable feedstock for the production of various value-added products like lactic acid.

So far, base catalysts have not been explored for this purpose, except for the hydrothermal conversion of glycerol to lactic acid using alkali metal catalysts like NaOH/KOH. This method presents several drawbacks for the industrial synthesis like harsh reaction conditions (excess temperature, excess amount of strong base, etc.) and cost-intensive isolation of soluble alkali metal lactates (excess catalysts) which is highly uneconomical. As a solution to this problem, scientists at Graz University of Technology, Austria have come up with a “green” method for the industrial synthesis of lactic acid by mixing a cocktail of dihydroxyacetone and calcium hydroxide.

The sparingly soluble calcium hydroxide facilitates the easy removal of excess catalyst by simple mechanical filtration making this a highly economical and industrial friendly method. Another component of the cocktail Dihydroxyacetone- is easily obtained by the microbial oxidation of glycerol in high yields, thus reducing the glycerol burden in the biodiesel industry.

The present paper discusses the catalytic effects of various earth metal hydroxides like barium hydroxide, calcium hydroxide and magnesium hydroxide on the lactic acid formation from dihydroxyacetone. The screening studies indicate that calcium hydroxide is highly selective towards formation of lactic acid owing to its chelation properties. The intriguing mechanism of lactic acid formation by alkali earth metal catalysis was investigated by the means of mechanistic and kinetic studies which suggested two major pathways for lactate synthesis. It was found that the temperature differences play an important role in the preference of the reaction to proceed via either pathway. Various other studies like the effect of concentration of catalyst, feed concentration, temperature variations provide a detailed insight into the synthesis of lactic acid from dihydroxyacetone.

The extensive studies done by the Austrian scientists, has not only provided a potential solution to the enigmatic problem of industrial synthesis of lactic acid, but has also provided a way to recycle the surplus glycerol into a high value product like lactic acid.

To know how the green cocktail made its way to become an industrially feasible method for the synthesis of lactic acid, read the article:

Synthesis of lactic acid from dihydroxyacetone: use of alkaline earth-metal hydroxides
Susanne Lux and Matthäus Siebenhofer
Catal. Sci. Technol., 2013, DOI: 10.1039/c3cy20859a

Platinum ‘peanuts’ to make better fuel cells

Sara Coles, Guest Web-Writer — Mon, 22 Apr 2013 08:47:23 +0000

Sara Coles is a guest web-writer for Catalysis Science & Technology. She currently works for Johnson Matthey in Royston, UK.

Shape controlled synthesis of catalytically active metal nanostructures is an important field of scientific research for both industry and academia. The arrangement of atoms on the particle surface is believed to play a critical role in the adsorption and desorption of substrates and products – which in turn affects the activity and selectivity of the catalyst. The chance to fine-tune these properties is too good to miss.

With this aim in mind, Sourov Ghosh and colleague, working in India, have experimented with different ways to shape platinum nanoparticles. Their report in Catalysis Science & Technology explains how they made and characterised ‘peanut-like’ and ‘dendrimer-like’ platinum nanoparticles to compare their performance in the hydrogenation of unsaturated alcohols and, supported on carbon nanotubes, in the oxygen reduction reaction (ORR).

The peanut-like particles showed significantly higher specific activity towards the ORR than the aggregated dendrimer-like particles or conventional quasispherical platinum nanoparticles. This makes them a promising choice for the fuel cell cathode due to their ability to promote faster electron transfer kinetics.

Read more about this work in the full paper.

Shape-controlled synthesis of Pt nanostructures and evaluation of catalytic and electrocatalytic performance
Sourov Ghosh and C. Retna Raj
Catal. Sci. Technol., 2013, 3, 1078, DOI: 10.1039/c2cy20652h