Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Catalysis: Blueprint for a break-up

05.07.2012
Computer simulations reveal how rhodium catalysts with ‘stepped’ surface structures break ethanol molecules into hydrogen atoms and why they are so efficient
Hydrogen gas (H2) is an ideal energy carrier for fuel cells, but finding sustainable ways to produce large quantities of hydrogen continues to be a technological challenge. Jia Zhang at the A*STAR Institute of High Performance Computing and co-workers have now used sophisticated calculations to uncover a critical chemical mechanism that may make catalytic transformation of safe, renewable liquid ethanol into hydrogen fuel easier than ever before.

Currently, steam reforming is the popular method for producing hydrogen gas from ethanol. In this technique, ethanol is injected into a hot, steam-filled chamber containing a catalyst such as rhodium. The catalyst promotes the dissociation of ethanol molecules into smaller molecules, such as carbon monoxide and H2. Although chemists have had good success in using steam reforming to ‘crack’ ethanol, they have had difficulties in improving the efficiency of the catalyst because of the many diverse and complex chemical reactions at play in the system.

According to Zhang, catalysts need to selectively crack the carbon–carbon bonds of surface-adsorbed ethanol to be viable for steam reforming. Recent experimental efforts have shown that ‘stepped’ catalyst surfaces — tiny staircase-like defects present in a normally flat rhodium surface — are unusually active at both carbon-hydrogen and carbon–carbon bond cleaving. One problem, however, is that the actual mechanism of ethanol decomposition on stepped surfaces is still unclear.

The research team overcame this challenge by using high-powered computer simulations to work out which ethanol decomposition pathways are most probable on a particular stepped rhodium surface known as rhodium (211). Exhaustive calculations using density functional theory (DFT) methods revealed that there were two ways of breaking ethanol down into H2, and both shared a common intermediate species with the chemical formula CH3COH.

Crucially, the team found that this CH3COH intermediate exists only on stepped rhodium surfaces. While flat catalyst surfaces fracture ethanol through an oxametallacycle intermediate, the step-type defects preferentially absorb the alcohol and then activate the decomposition cycle by sequentially removing hydrogen atoms from the intermediate. The researchers note that the surface-sensitivity of ethanol steam reforming is an important finding because step-defects are extremely common on state-of-the-art nanoscale rhodium catalysts.

“Steam reforming is a very complicated chemical process, and our current DFT study on ethanol decomposition mechanism is just the tip of the iceberg — many factors such as temperature, concentration, substrate influence, and water effects can influence the results,” says Zhang. “However, this work is an important first step for establishing theoretical rules to guide development of new, high-performance catalyst materials.”

The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing

References:

Zhang, J. et al. Density functional theory studies of ethanol decomposition on Rh(211). Journal of Physical Chemistry C 115, 22429–22437 (2011)

A*STAR Research | Research asia research news
Further information:
http://www.research.a-star.edu.sg
http://www.researchsea.com

More articles from Information Technology:

nachricht Powerful IT security for the car of the future – research alliance develops new approaches
25.05.2018 | Universität Ulm

nachricht Supercomputing the emergence of material behavior
18.05.2018 | University of Texas at Austin, Texas Advanced Computing Center

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>