Method allows to obtain simpler, safer and cheaper acetone – 04/09/2023 – Science

An essential input in the chemical industry, acetone is used in the manufacture of a wide variety of products, such as adhesives, antibiotics, electronic components, solvents and removers, printing inks and vitamins, among others. Its production process, however, is elaborate and dangerous.

To simplify it, make it safer and reduce costs, a group of researchers from Brazil and Germany developed an unprecedented method, which uses only light and a cheap chemical compound: iron chloride (FeCl3).

The results of the research, funded by FAPESP, were published in the journal ACS Catalysis.

Known as Hock or cumene, the standard process for manufacturing acetone involves several steps: first, propane – a petroleum by-product – is transformed into propylene, an extremely flammable gas that reacts with benzene and then with oxygen at high temperatures. temperatures and pressures to give rise to acetone. These reactions also generate a compound called phenol – which has a lower demand and generates a cost to be transformed into substances of greater value.

The alternative method, proposed by scientists from the Federal University of São Carlos (UFSCar), Federal University of Minas Gerais (UFMG) and the Max Planck Institute of Colloids and Interfaces (Germany), is based on the oxidation of propane using iron chloride as a catalyst homogeneous in the presence of light (photocatalytic reaction).

“We discovered that, when irradiated with certain wavelengths, iron chloride generates the chlorine radical, which is extremely oxidizing and activates the CH bond, that is, it breaks the bond between carbon and hydrogen, giving rise to a radical which, in the presence of oxygen, leads to the formation of acetone”, explains Ivo Freitas Teixeira, professor at the Department of Chemistry at UFSCar and coordinator of the study.

“We carried out a very important reaction in an absolutely different way and using very simple elements.”

Proof that the reaction was actually driven by chlorine radicals generated by photolysis of the Fe-Cl bond was done through mechanistic studies, including mass spectrometry analyzes (which allow identifying the components of a mixture based on the molecular weight of each element).

Among the advantages of the new process are the fact that it is direct (there is no production of propylene in intermediate stages) and safer, as it does not involve oxygen reactions at high pressures and temperatures, nor flammable and dangerous intermediates. In addition, it reduces energy expenditure and cost, as it has fewer steps and takes place at an ambient temperature of 25 °C.

Although the experiments used an LED-type light source, the idea is that, in the future, it can be replaced by sunlight, making the method even more sustainable.

Patent filing and next steps

With the patent already deposited at the National Institute of Industrial Property (INPI), the idea now is to seek partnerships with companies to finance the scaling up of the new process to a commercial level.

“This method can become absolutely disruptive for the production of acetone in the chemical industry, making the process safer and more sustainable and enabling a route for the production of acetone only, which would reduce costs and bring competitiveness”, says Teixeira.

According to the researcher, the main challenge in this case is due to the fact that, in the petrochemical industry, processes take place on a large scale and currently there is no commercial photocatalytic method.

The research project also continues to evolve in two directions: while testing the new method with other substances, such as methane, the researchers are now also thinking of ways to scale the process and adapt it to the industry so that it achieve higher production and utilization.

The article Direct Synthesis of Acetone by Aerobic Propane Oxidation Promoted by Photoactive Iron(III) Chloride under Mild Conditions can be read here.