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From garbage to fuel — zeolite catalyst concept Zeolite Catalyst. Source: TUM Fotostelle.

Making fuel from waste is often considered economically unviable due to high temperatures and too much energy being required. However, 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 being the reaction takes place in very confined spaces inside zeolite crystals.


ver more electricity is

faster than without the zeolite catalysts.

as the one that causes wax to stick to a

produced decentrally us-

“We thought about how we could apply

tabletop and that allows geckos to walk on

ing wind, hydro and solar

these biological functions to organic chemis-

ceilings,” replied Lercher. “The more contact

power plants. “It thus

try,” explained Lercher. “While searching for

points there are between two surfaces, the

makes sense to decentral-

suitable catalysts that accelerate the reac-

larger the adhesion. In our experiments, the

ise chemical production,

tion, we stumbled upon zeolites — crystals

organic molecules, which are in an aqueous

as well,” thinks Prof. Johannes Lercher, who

with small cavities in which the reactions

solution, are literally attracted to the pores

heads the Chair of Technical Chemistry II at

take place under cramped conditions com-

in the zeolites.”

TU Munich. “Theoretically, any municipality

parable to those in enzyme pockets.”

could produce its own fuel or fertiliser.”

Thus, the hydronium ions within the cavi-

Lercher’s team compared the reactions of

ties have a significantly greater likelihood of

To date, this has not been possible be-

carbon compounds with acids in a beaker

bumping into a reaction partner than those

cause chemical processes require a great

to the same reactions in zeolites. The

outside. The result is an acid catalysed

deal of energy — more than local renew-

result: in the crystal cavities, where the

chemical reaction that takes place faster

able energy sources can provide. “We thus

reacting molecules, for example alcohols,

and with lower energy input.

aimed at finding new processes to lay the

meet upon the hydronium ions of the acids,

When they come into contact with hy-

foundations for the distributed production

reactions run up to 100 times faster and at

dronium ions, organic molecules such as

of chemicals, which can be powered us-

temperatures just over 100°C.

alcohols lose oxygen. This makes the process

ing renewable energy sources,” explained

“Our experiments demonstrate that

the chemist, who is also director of the

zeolites as catalysts are similarly effective

suitable to converting bio-oil obtained from

American Institute for Integrated Catalysis

as enzymes: both significantly reduce the

It will take some time, of course, before

at Pacific Northwest National Laboratory.

energy levels required by the reactions,”

the new process can be deployed in the field.

organic waste into fuel.

His team has now fulfilled one prerequi-

reported Lercher. “The smaller the cavity,

“We are still working on the fundamentals,”

site for a turnaround in chemical production.

the larger the catalytic effect. We achieved

emphasised Lercher. “We hope to use these

In the laboratory, the scientists demonstrated

the best results with diameters far below

to create the conditions required for new,

that the temperature required for splitting

one nanometre.”

decentral chemical production processes

carbon-oxygen bonds in acidic aqueous

But why do tight spaces foster the

solution can be drastically reduced using

reactivity of molecules? “The force that

Technical University of Munich (TUM)

zeolite crystals. The process also ran much

improves the reaction path is the same

24 Sustainability Matters - Aug/Sep 2017

that no longer require large-scale facilities.”

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Sustainability Matters Aug/Sep 2017  

Sustainability Matters is a bi-monthly magazine showcasing the latest products, technology and sustainable solutions for industry, governmen...

Sustainability Matters Aug/Sep 2017  

Sustainability Matters is a bi-monthly magazine showcasing the latest products, technology and sustainable solutions for industry, governmen...