Researchers are studying equipment capable of capturing CO2 from gases arising from the combustion of sugarcane biomass

A group of researchers from the University of São Paulo (USP) and the Federal University of Ceará (UFC) is investigating whether it is possible, through adsorption systems, to capture carbon dioxide (CO2) from gases from the combustion of sugarcane biomass. of sugar. “The adsorption process is already used for other purposes in national and international industry, such as, for example, to clean an air stream contaminated by ammonia or purify natural gas. However, it is a process that has not yet been applied to capture CO2 from the biomass that generates ethanol. This is one of the new features of our research”, explains chemical engineer Marcelo Martins Seckler, professor at the Polytechnic School of the University of São Paulo (Poli-USP) and project coordinator. Optimization of temperature modulation adsorption systems -- Temperature Swing Adsorption (TSA) -- for capture of CO2.

The project is developed within the scope of the Research Center for Greenhouse Gas Innovation (RCGI), a research center financed by the São Paulo Research Foundation (Fapesp) and Shell. “Currently, the separation process most used by the industry is absorption. In this case, the gas passes through a liquid, which then captures the CO2. However, this process consumes a lot of energy”, says Seckler, who worked for more than two decades at the Institute for Technological Research (IPT) and was also a professor at the Technical University of Delft, in the Netherlands. “On the other hand, the adsorption process, which we use in our research, is more economical in energy terms. This is because it replaces the liquid with a highly porous solid material. To give you an idea, one gram of this particle can house around a thousand square meters of pores. Thanks to this characteristic, the material has a great capacity to attract carbon dioxide, making the CO2 capture process faster and more effective.”

Small and large scale -- The project is being carried out on two fronts. In one of them, researchers from the UFC's Chemical Engineering department, led by professor Diana Cristina Silva de Azevêdo, study the adsorption process experimentally on a small scale. “It is a group specialized in this type of operation, with excellent laboratory infrastructure. They will carry out experiments to understand how gases from biomass behave during adsorption”, reports Seckler. “The reason is simple: we want to understand how we can efficiently separate CO2 in the presence of impurities typical of this type of gas.”

On another front, researchers from USP will study the feasibility of applying the proposal on a large scale, as in the case of a sugar cane factory, for example. “It’s a process that involves many steps”, points out Seckler. As there is no industrial equipment built for this purpose yet, the team will simulate the entire process on a computer. “We need to think, for example, about the construction details of the equipment to avoid problems such as poor distribution of gas and solid material. This is because when these two elements are not distributed evenly inside the equipment, they cannot interact in an ideal way, which, consequently, harms the separation process.”

Topological optimization -- To optimize equipment performance, the project will use topological optimization, a technique created in the 1980s in the United States by Danish mathematician Martin Philip Bendsoe and Japanese mechanical engineer Noboru Kikuchi. It is a computational tool used in the design of high-performance structures, which seeks to find the most appropriate distribution of materials within a specific space. “It is a technique that was born and applied in the field of mechanical engineering, but its use has been expanding over time”, says mechatronic engineer Emílio Carlos Neli Silva, professor at Poli-USP and vice-coordinator of the project. “At RCGI, we use topological optimization in the area of ​​fluids and chemistry and, in the case of this particular project, we adopted the model in fluidized bed systems, which is a novelty in the world”, continues Silva.

The researcher is one of the pioneers of topological optimization in Brazil, an area in which he has worked since the 1990s, when he returned from his doctorate at the University of Michigan (USA), under the guidance of Kikuchi, now president of the study center at the automaker Toyota. According to Silva, to further determine the accuracy of the equipment, the team is also considering using artificial intelligence during the process. “Fluidized bed systems are extremely complex chemical reactions. The human brain cannot manage alone, without the help of machines, all the expertise necessary to design a device with the aim of our project, which is to improve the adsorption of CO2. It is an operation that demands high sensitivity: if we change a small detail related to temperature, for example, we can improve or worsen the process”, says the specialist.

Finally, researchers based in São Paulo and Fortaleza will link experimental and modeling studies to develop design methods for the industry. “The knowledge generated in this project will allow, for example, to offer subsidies to companies interested in building equipment capable of capturing CO2 from gases from the combustion of sugarcane biomass. In the near future, this equipment could be installed in industries in the sugar and alcohol sector and contribute to the production of green ethanol, without CO2 emissions”, predicts Seckler.