Cellulose Fibers Against Climate Change

November 3, 2021

Protecting the global climate is a major undertaking for both industry and society. It will not be possible to achieve climate goals simply by limiting global emissions, saving carbon dioxide (CO2). This is because there will continue to be unavoidable CO2 emissions which, however, will have to be offset. The solutions to this unfortunate situation can be measured as reforestation, carbon sequestration in the soil or even the active capture of CO2 from the air. In one process, special filters are used to remove CO2 from the atmosphere. As part of a research project, the DITF is developing textile materials to separate CO2 from the air.

CO2 can thus be fixed in the long term and thus permanently removed from the climate cycle. Or it can be used as a feedstock for the production of CO2 neutral hydrocarbons.

Although several companies are already competing internationally to find the best technology to extract CO2 from the air in large quantities and profitably, economic aspects continue to hinder the really big progress: The small proportion of CO2 in the atmosphere (0.04% ) requires huge amounts of air to be pumped through the filters to filter out a significant proportion of CO2. In turn, the removal of the carbon dioxide absorbed by the filters requires large amounts of thermal energy. Economical operation is not possible under current conditions. Therefore, in the future development of the separation of CO2 from air, it will be necessary to take several turns of the screw to increase the technological efficiency of the process and minimize energy consumption.

Self-sufficient air filter for CO2 separation

A joint research project of the Baden-Württemberg Solar and Hydrogen Research Center, Denkendorf DITF, Heidelberg Institute for Energy and Environmental Research and Sindelfingen Mercedes-Benz AG aims to capture CO2 from the air improved and highly efficient using tissue-bound amines. The process will be applied in a demonstrator that can work autonomously: the consumption of resources will be based exclusively on renewable electricity and waste heat, covered by solar energy or heat pumps. The special design of the air filter will allow the continuous operation of the plant, unlike the already established processes. This improves scalability on an industrial scale.

Within this four-year joint research project, the DITF brings its many years of experience in the development of cellulose-based fiber materials. They will be used as filter media in the demonstrator. Based on the results of a previous research project, in which a screening of the possible processes for the removal of CO2 from the air and the absorbent materials used for this had already been carried out, cellulose fiber materials were chosen for the current investigation project.

Optimized cellulose fibers from Denkendorf

Under the direction of Dr. Frank Hermanutz, the fibers for the filters are spun at the Biopolymer Materials Competence Center and chemically modified to couple amines to their surface. To this end, new spinning processes are being developed and optimized in the DITF pilot plants. The amines ensure the temporary binding of CO2 to the filter material. The advantage of using cellulose fibers lies in the open and air-permeable structure of fiber-based materials. Not only do they allow a large air flow, but they also have a large specific surface area, which is advantageous for binding the largest possible volumes of CO2.

A completely new process engineering concept is pursued in the filter design: A static filter is not used, as is often the case, which has to be fired after the amino groups have been fully charged with CO2. Instead, the filtration process is integrated into a continuous running process that allows for continuous, energy-saving operation. If the system is connected to existing air currents, such as building air conditioning systems or exhaust air, it is not necessary to use energy-intensive fans.

The filter is designed as a special belt apparatus in which cellulose fibers are transformed into endless ribbons in the form of nonwovens. These belts, like a conveyor belt, travel on rollers through the incoming air stream and bind the CO2 there. The tapes are then heated in three temperature zones in a spatially separated desorption area. There, the water and CO2 are separated from the amino groups.

The continuous process made possible by circulating nonwoven tapes saves costs and controls the process with little maintenance. In addition to CO2 extraction, separate water extraction will also represent a synergistic effect of great value: Since the plant is already designed for energy self-sufficient operation, in principle it is possible to operate it in areas with poor infrastructure and water scarcity. The collection of water can therefore represent a not inconsiderable added value. The design as a tape drive makes it easy to expand the process to very high performance classes, since this requires above all an increase in the length of the tape that is easy to implement.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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