Two composites will be obtained from sugarcane biomass; CO2 takes the place of phosgene gas

Producing plastic and other polymeric materials that are not derived from petroleum is the goal of the project Integrating the chemicals CO2 and ethanol to prepare bio-based polyurethanes, performed within the scope of the Research Centre for Innovation in Greenhouse Gases (RCGI), which is funded by the São Paulo Research Support Foundation (FAPESP) in a partnership with Shell. The study is being carried out by researchers at the São Carlos Chemical Institute of the University of São Paulo (IQSC-USP). “Brazil is a huge producer of ethanol. One of our ideas is to make use of sugarcane bagasse, which is practically always thrown away and used as fuel for heating the boilers, to create organic molecule from which a sustainable plastic will be derived,” says Antonio Carlos Bender Burtoloso, Professor at IQSC-USP and Project Coordinator.

The researchers are focusing on polyurethanes, which are versatile polymeric materials heavily used by industries and found in foams, glues, high-performance adhesives, and skateboard wheels, for example. “The chemical constitution of polyurethanes is simple. Generally speaking, it results from the combination of only two monomers, which we call smaller molecules: in this case, an isocyanate and a polyol. These monomers are like pieces of a puzzle. In polymerization reactions, they come together and form long and ramified molecules. These, then, form plastic or another polymeric material,” the researcher explains.

According to Burtoloso, isocyanate is a composite commonly used in polymerization reactions. In this case, the industrial preparation of this composite is usual done from a combination of amines and phosgene gas. “Despite being a cheap option and performing very well in this situation, phosgene gas is an extremely toxic product and that is harmful to our health and the environment,” he says. At the present time, the project team is investigating ways of substituting phosgene gas with carbon dioxide (CO2) in the chemical structure of isocyanate. “Besides not being toxic, this alternative helps reduce the concentration of carbon dioxide in the atmosphere, which is one of the biggest villains of the greenhouse effect, by transforming CO2 into a product that could be used by industries.”

Other research groups in Brazil and around the world have been studying ways to make this substitution. “The results are promising, but each team has its own approach, which differs in the reagents and reaction methods used throughout the research,” says Burtoloso. Throughout the project, the group has prepared, for example a specific type of amine. “This amine that we synthesized is produced from sugarcane biomass, instead of petroleum, as is the case of the amines generally used by industries,” Burtoloso adds.

RCGI researchers are also looking at polyol, which is another key element in the chemical structure of polyurethanes. “Practically all of the polyols used industrially in preparing polyurethanes are derived from petroleum, but we intend to prepare them from sugarcane bagasse,” he explains. “The cellulose found in bagasse is a sugar polymer that breaks down and is the origin of several substances, above all levulinic acid, after an acid bath. Levulinic acid can be transformed into another molecule, valerolactone. From this, we will make a whole series of polyols that totally come from biomass. Our team has already constructed some of them in a very efficient manner.”

The project is an offshoot of another study done between 2018 and 2021, at the IQSC-USP, also under the direction of Burtoloso. “At that time, we were able to produce a plastic with polyol totally taken from sugarcane bagasse, but the isocyanate was derived from petroleum. Now we want to produce other polyols, as well as isocyanate, all from biomass. Not to mention the idea of substituting phosgene gas with CO2. It’s a stiff challenge.”

Burtoloso reminds that despite the good results obtained so far, there is a long road ahead to obtaining the industrial production of this type of plastic, and it goes beyond the walls of the university. “It is a process that takes time and involves numerous stages. To start with, the prototype of the plastic developed in the laboratory must be evaluated by an engineer or a materials chemist, who will check on such factors as product durability and flexibility,” he points out. Furthermore, the plastic prototype must also go through a cost assessment to check on the product’s competitiveness on the market. Another point to be checked is the viability of large-scale production of the invention.

The challenge does not intimidate Burtoloso, who is a specialist in organic synthesis with post-Doctoral studies at the Scripps Research Institute, located in California (U.S.). “Our work in organic synthesis is to build molecules. This is an area of chemistry that demands a lot of creativity on the part of professionals.” According to him, organic synthesis is constantly used in medicinal chemistry, for example. “More than 80% of the medications we use are synthetic. Generally speaking, these drugs are made from molecules inspired by natural substances, but that were modified so as to strengthen their effects. A specialist in organic synthesis can both improve something that already exist and create something totally new. The sky is the limit.”


About the RCGI – The Research Centre for Innovation in Greenhouse Gases (RCGI) is an Engineering Research Centre created in 2015, with funding by FAPESP and Shell. The research of the RCGI is focused on innovations that make it possible for Brazil to achieve the commitments assumed in the Paris Agreement, within the scope of the Nationally Determined Contributions (NDC). The full 19 research projects are anchored within five programs: Nature-Based Solutions (NBS); Carbon Capture and Utilization (CCU); Bioenergy with Carbon Capture and Storage (BECCS); Greenhouse Gases (GHG); and Advocacy. The Centre currently has about 400 researchers. Learn more here.




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