Nav: Home

Bio-fuel from waste

June 28, 2017

Fuel from waste? It is possible. But hitherto, converting organic waste to fuel has not been economically viable. Excessively high temperatures and too much energy are required. Using a novel catalyst concept, researchers at the Technical University of Munich (TUM) have now managed to significantly reduce the temperature and energy requirements of a key step in the chemical process. The trick: The reaction takes place in very confined spaces inside zeolite crystals.

Ever more electricity is produced decentrally using wind, hydro and solar power plants. "It thus makes sense to decentralize chemical production, as well," thinks Prof. Johannes Lercher, who heads the Chair of Technical Chemistry II at TU Munich. "Theoretically, any municipality could produce its own fuel or fertilizer."

To date, this has not been possible because chemical processes require a great deal of energy - more than local renewable energy sources can provide. "We thus aimed at findinding new processes to lay the foundations for the distributed production of chemicals, which can be powered using renewable energy sources," explains the chemist, who is also Director of the American Institute for Integrated Catalysis at Pacific Northwest National Laboratory.

His team has now fulfilled one prerequisite for a turnaround in chemical production: In the laboratory, the scientists demonstrated that the temperature required for splitting carbon-oxygen bonds in acidic aqueous solution can be drastically reduced using zeolite crystals. The process also ran much faster than without the zeolite catalysts.

Nature as a model

Nature provided the reference for the development of the new process. In biological systems, enzymes with small pockets in their surface accelerate chemical processes.

"We thought about how we could apply theses biological functions to organic chemistry," explains Lercher. "While searching for suitable catalysts that accelerate the reaction, we stumbled upon zeolites - crystals with small cavities in which the reactions take place under cramped conditions comparable to those in enzyme pockets."

Cornered hydronium ions

But, do cramped quarters really increase the reactivity? To answer this question, Lercher's team compared the reactions of carbon compounds with acids in a beaker to the same reactions in zeolites. The result: In the crystal cavities, where the reacting molecules, for example alcohols, meet upon the hydronium ions of the acids, reactions run up to 100 times faster and at temperatures just over 100 °C.

"Our experiments demonstrate that zeolites as catalysts are similarly effective as enzymes: Both significantly reduce the energy levels required by the reactions," reports Lercher. "The smaller the cavity, the larger the catalytic effect. We achieved the best results with diameters far below one nanometer."

Geckos, wax and zeolites

But why do tight spaces foster the reactivity of molecules? "The force that improves the reaction path is the same as the one that causes wax to stick to a tabletop and that allows geckos to walk on ceilings," replies Lercher. "The more contact points there are between two surfaces, the larger the adhesion. In our experiments, the organic molecules, which are in an aqueous solution, are literally attracted to the pores in the zeolites."

Thus, the hydronium ions within the cavities have a significantly greater likelihood of bumping into a reaction partner than those outside. The result is an acid catalyzed chemical reaction that takes place faster and with lower energy input.

From garbage to fuel

When they come into contact with hydronium ions, organic molecules such as alcohols lose oxygen. This makes the process suitable to converting bio-oil obtained from organic waste into fuel.

It will take some time, of course, before the new process can be deployed in the field. "We are still working on the fundamentals," emphasizes Lercher. "We hope to use these to create the conditions required for new, decentral chemical production processes that no longer require large-scale facilities."
-end-
The work was developed in a cooperation of the Chair for Technical Chemistry II and the Catalysis Research Institute at the Technical University of Munich with the Pacific Northwest National Laboratory (PNNL). They were funded by the U.S. Department of Energy (DOE). Some of the NMR experiments were performed at the PNNL's Environmental Molecular Science Laboratory (EMSL). PNNL's National Energy Research Scientific Computing Center (NERSC) provided simulation time.

Publications:

Enhancing the catalytic activity of hydronium ions through constrained environments
Y. Liu, A. Vjunov, H. Shi, S. Eckstein, D. M. Camaioni, D. Mei, E. Barath, J. A. Lercher
Nat. Comm., 8, 14113 (2017) - DOI: 10.1038/ncomms14113

Tailoring nanoscopic confines to maximize catalytic activity of hydronium ions
H. Shi, S. Eckstein, A. Vjunov, D.M. Camaioni, J.A. Lercher
Nat. Comm., 8, 14113 (2017) - DOI: 10.1038/ncomms15442

Technical University of Munich (TUM)

Related Molecules Articles:

Discovery of periodic tables for molecules
Scientists at Tokyo Institute of Technology (Tokyo Tech) develop tables similar to the periodic table of elements but for molecules.
New method for imaging biological molecules
Researchers at Karolinska Institutet in Sweden have, together with colleagues from Aalto University in Finland, developed a new method for creating images of molecules in cells or tissue samples.
How two water molecules dance together
Researchers have gained new insights into how water molecules interact.
Hand-knitted molecules
Molecules are usually formed in reaction vessels or laboratory flasks.
How molecules teeter in a laser field
When molecules interact with the oscillating field of a laser, an instantaneous, time-dependent dipole is induced.
Data storage using individual molecules
Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled.
Small molecules come into focus
Many biologically important small molecules, like hormones and amino acids, are too small to be measured by conventional detection methods.
We now know how RNA molecules are organized in cells
With their new finding, Canadian scientists urge revision of decades-old dogma on protein synthesis
A new way to create molecules for drug development
Chemists at The Ohio State University have developed a new and improved way to generate molecules that can enable the design of new types of synthetic drugs.
How ions gather water molecules around them
Charged particles in aqueous solutions are always surrounded by a shell of water molecules.
More Molecules News and Molecules Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.