How does chemical produce electricity



20.03.2017 14:26

Electricity as a raw material: Green energy for sustainable chemistry

Dipl.-Chem. Iris Kumpmann Public Relations Department
Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT

The energy transition and the resulting low-CO2 electricity offer the opportunity to set up electricity-controlled production. Ten Fraunhofer institutes develop and optimize processes that use this electricity to produce important basic chemicals. At HANNOVER MESSE 2017 (April 24 to 28, Hall 2, Stand C22), Fraunhofer UMSICHT is presenting the Fraunhofer lead project “Electricity as a Raw Material”.

The stainless steel cylinder is in a solid metal frame, various hoses lead into it. With a diameter of 20 cm, it looks quite massive. However, its internal volume is surprisingly small - no larger than a beverage can. There is a reason for this: the cylinder has extremely thick steel walls that can withstand a pressure of 150 bar, 150 times atmospheric pressure.

The prototype is at Fraunhofer UMSICHT in Oberhausen. It is supposed to produce alcohols such as ethanol from CO2 and water - important basic chemicals for industry. However, the process is not driven by fossil-based process heat, but by green electricity generated from renewable sources.

Produce chemicals in a climate-friendly way

The high pressure process is part of the Fraunhofer lead project "Electricity as a raw material". "When you talk about the energy transition, you first think of electromobility," says project coordinator Dr. Hartmut Pflaum. But it is just as important to reduce industrial CO2 emissions. In order to manufacture chemicals, for example, high temperatures are often required. The production is correspondingly energy-intensive, accompanied by high CO2 emissions. In their lead project, the Fraunhofer researchers are working on processes with which chemicals can be produced in a climate-friendly manner in the future - using green electricity.

Around 30 percent of our electricity is already generated from renewable sources. However, production fluctuates: In sunshine and strong winds, wind turbines and solar cells sometimes supply more electricity than is acutely needed in the grid. "Electricity-based production processes can help to make intelligent use of supply and thus price fluctuations in the electricity grid and to partially replace fossil-fueled processes in the long term," explains Dr. Plum.

Two processes

This is made possible by electrochemistry. As part of the Fraunhofer lead project “Electricity as a Raw Material”, the experts are devoting themselves to the development of two different processes: On the one hand, they want to produce hydrogen peroxide (H2O2) - a disinfectant and bleaching agent - simply and reliably using electricity. On the other hand, they are trying to generate valuable basic chemicals from electricity and CO2 - ethene and various alcohols.

Hydrogen Peroxide Production On Demand

Hydrogen peroxide is considered an environmentally friendly bleaching agent; it is used on a large scale in papermaking to bleach the pulp. So far, the industry has produced the agent using the anthraquinone process. However, this not only requires organic solvents, but also a lot of energy. That is why the Fraunhofer researchers are working on an alternative that works with electricity. The principle: Similar to a battery, the reactor contains a minus and a plus pole. If you apply electricity, protons are formed that can react with oxygen. If the optimum current and voltage values ​​can be set and the correct catalyst used, hydrogen peroxide is produced. The challenge is to create conditions in which the hydrogen peroxide remains stable in a solution for a longer period of time.

Specifically, the researchers are developing two variants: In the first, they are working on a reactor in which a membrane separates the two poles. The decisive factor is to find a catalyst for the negative pole that initiates the reaction of hydrogen and oxygen to form hydrogen peroxide as effectively as possible. The second method is based on a diamond electrode. It is already being used for wastewater disinfection. The experts are trying to modify it so that it can also produce hydrogen peroxide.

Both variants work, but the concentration of hydrogen peroxide still has to be increased. "At the end of the day, we should find out which of the two processes works better," explains Dr. Plum. “Our aim is to bring both methods close to being ready for practical use.” The vision: On the premises of a pulp manufacturer, electrochemical reactors - possibly using electricity from a neighboring wind farm - always produce as much bleach as the paper manufacturer needs: hydrogen peroxide production On demand.

Convert CO2 electrochemically into products

The other branch of the lead project is much more fundamentally oriented. Here the experts want to try to make important electricity and CO2
To produce basic chemicals that are conventionally obtained from petroleum
become. While there is an abundance of CO2, it is inert and reluctant to form compounds. "In order for it to react chemically, we have to activate it," explains Dr. Plum. "As part of our lead project, we are developing three prototypes that convert CO2 electrochemically into products."

• Ethene is a key pre-product for the manufacture of the standard plastic polyethylene. The Fraunhofer experts are developing a reactor based on a gas diffusion electrode. In it, CO2 comes into contact with an electrolyte. Ethene is produced at the electrode with the help of a catalyst.

• Short-chain alcohols such as ethanol and propanol serve as standard reaction partners in organic chemistry, but can also be used as fuel. With a new type of high-pressure reactor, the scientists are working on chemically activating compressed CO2 and allowing it to react with hydrogen to form alcohol molecules.

• Long-chain alcohols act as plasticizers, surfactants and fuel additives, among other things. In order to generate them in a climate-friendly way, the researchers are developing a two-stage process: First, they use high-temperature electrolysis to generate a synthesis gas consisting of carbon monoxide and hydrogen from water and CO2. This gas is then linked to form long alcohol molecules in a Fischer-Tropsch synthesis.

"If we succeed in showing the feasibility of these processes, they will be attractive alternatives for the chemical industry," says Dr. Plum. Then the new, climate-friendly methods could be developed into pilot systems together with industry.

HANNOVER MESSE 2017

Fraunhofer UMSICHT will be represented at HANNOVER MESSE from April 24 to 28, 2017, at the joint Fraunhofer-Gesellschaft booth (Hall 2, Booth C22). The following exhibits are on display:

• Co-electrolysis stack
High-temperature stable stack made of ceramic solid oxide cells for power-to-gas processes and vice versa.

• Model of a high-pressure electrical synthesis apparatus
A replica of a high-pressure cell with integrated electrodes is exhibited in a plexiglass-like structure made of plexiglass. The cylinder-shaped structure has a diameter of approx. 80 cm.

• Membrane pattern
Membrane pattern of an inexpensive, proton-conducting membrane with a low fluorine content based on alternative polymer classes
(Size 7 cm x 7 cm) for the electrochemical H2O2 synthesis.

• Simulation, multi-criteria optimization, decision support: application of electrosynthesis
Interactive software for the visualization and analysis of multivariate data sets as well as for decision support.

Fraunhofer lead project

With its lead projects, the Fraunhofer-Gesellschaft sets strategic priorities in order to quickly convert scientific ideas into marketable products and concrete solutions for industry. The participating Fraunhofer institutes contribute their skills and involve industrial partners at an early stage. Ten institutes have joined forces in the lead project “Electricity as a Raw Material”: UMSICHT (lead), IAP, ICT, IGB, IKTS, ISC, IST, ITWM, IVV and WKI. The project started on August 1, 2015 and is expected to be completed on July 31, 2018.


Additional Information:

http://s.fhg.de/ikD Further information on the Fraunhofer lead project "Electricity as a Raw Material"


Features of this press release:
Journalists, scientists
Chemistry, energy
supraregional
Research / knowledge transfer, research projects
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