Air, Water and Electricity: Scientists at MIT have improved the anthraquinone process.
Hydrogen peroxide (peroxide) is a drug used to disinfect wounds and surfaces, as well as a bleaching agent. In its composition, peroxide differs from water by an additional oxygen molecule, having the chemical formula H2O2. The discoverer, chemist Louis Jacques Thénard, obtained it two centuries ago using the reaction of barium and nitric acid. Later, it was mined by electrolysis and subsequent hydrolysis of sulfuric acid.
Today it is synthesized in the framework of the anthraquinone process - the oxidation of hydrogen with oxygen in the presence of a catalyst, an alkyl anthrahydroquinone molecule. Pros - there is a lot of peroxide at the outlet, cons - it is very inconvenient if the substances necessary for production need to be delivered to geographically remote places.
For example, hydrogen for this process is usually obtained from methane, an explosive gas. And the reaction product itself is explosive: it is impossible to transport peroxide in pure form or slightly diluted (more than 35% peroxide). In addition, toxic metals such as mercury or lead are often used to speed up the process in the reactor. This increases the potential harm of the anthraquinone process to the environment.
The authors of the work, published in Joule, proposed a method that will help to sustainably obtain hydrogen peroxide in any settlement, community or enterprise remote from the mainland. To do this, they modified the anthraquinone process: instead of obtaining hydrogen from methane, scientists proposed to extract H2 by electrolysis (decomposition under the influence of an electric current) of water. The hydrogen obtained by this method is then fed in the usual way into a flow reactor, where it forms peroxide in an oxygen-saturated atmosphere.
“It's an amazing process in its own way, because you take a lot of ingredients - water, air, electricity - that you can get right on the spot and use them to produce an important chemical that you can then use to actually clean up the environment,” says one of the authors of the work Yogesh Surendranath. The experimental setup assembled by scientists has already demonstrated good performance with minimal energy consumption.
The authors of the work note that the anthraquinone process can be modified. The most promising is the change in the concentration of the catalyst in the flow reactors or the selection of another, more economical catalyst.
Earlier, scientists from the University of Cambridge proposed using artificial photosynthesis to produce synthesis gas (a mixture of oxygen and hydrogen), and specialists from Stanford have developed a gel to prevent forest fires.