Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Research reveals mechanism for direct synthesis of hydrogen peroxide

21.01.2016

From the polyurethane that makes our car seats to the paper made from bleached wood pulp, chlorine can be found in a variety of large-scale manufacturing processes. But while chlorine is good at activating the strong bonds of molecules, which allows manufacturers to synthesize the products we use on a daily basis, it can be an insidious chemical, sometimes escaping into the environment as hazardous byproducts such as chloroform and dioxin.

As a result, scientists and companies have been exploring a more environmentally benign alternative to chlorine--hydrogen peroxide, or H2O2. But it is an expensive reactant. Hydrogen peroxide is typically made in big, centralized facilities and requires significant energy for separation, concentration, and transportation.


Instead of reacting together on the surface of the catalyst (the palladium cluster), the hydrogen atoms dissociate into their components -- protons and electrons. The protons enter the surrounding solution of water and methanol, while the electrons flow through the palladium itself into oxygen molecules.

Credit: American Chemical Society

A handful of large-scale facilities around the globe have begun to produce H2O2 using the current process, but at the same facilities as the polyurethane precursors, which results in significant cost and energy savings and reduces environmental impact.

Ideally smaller-scale factories would also be able to make hydrogen peroxide on site, but this would require a completely different set of chemistry, direct synthesis of H2O2 from hydrogen and oxygen gas, which has long been poorly understood according to researchers at the University of Illinois at Urbana-Champaign.

New research from David Flaherty, assistant professor of chemical and biomolecular engineering, and graduate student Neil Wilson reveals the mechanism for the direct synthesis of H2O2 on palladium cluster catalysts, and paves the way to design improved catalysts to produce H2O2 to use in place of harmful chlorine, regardless of the scale of the production facility. The research appears as the cover story for the Jan. 20, 2016 issue of the Journal of the American Chemical Society.

The commonly accepted mechanism for direct synthesis of H2O2 essentially states that hydrogen and oxygen atoms bind adjacent to one another on the catalyst surface and then react, Wilson said. To better understand what was going on, he spent over a year building a reactor, fine-tuning experimental procedures, then collecting and analyzing reaction rate data.

"What people thought was happening is after the hydrogen atoms broke apart and they're adsorbed onto the palladium surface, that they just reacted with the oxygen on the surface. But that's not really consistent with what we saw," said Wilson, a fourth-year graduate student in Flaherty's lab and first author of the article, "Mechanism for the Direct Synthesis of H2O2 on Pd Clusters: Heterolytic Reaction Pathways at the Liquid-Solid Interface."

Featured on the journal's cover is an image that depicts their findings: Instead of reacting together on the surface of the catalyst (the palladium cluster), the hydrogen atoms dissociate into their components--protons and electrons. The protons enter the surrounding solution of water and methanol, while the electrons flow through the palladium itself into oxygen molecules.

"When oxygen comes down onto the surface, it can react with pairs of protons and electrons to form hydrogen peroxide," Wilson said.

"The reason this is critical," Flaherty said, "is because it gives us guidance for how to make the next generation of these materials. This is all motivated by trying to make hydrogen peroxide more cheaply so it can be manufactured more easily, so we can use it in place of chlorine. But we didn't know how to go about making a catalyst that was better than what we have now."

Researchers will now have a better sense of what is happening at the catalyst surface and an appreciation for the role of proton and electron transfer processes in this chemistry. It was not recognized that the oxygen on the surface reacted with liquid phase species, and that the formation of H2O2 by direct synthesis is, therefore, strongly influenced by the solution itself. However, the formation of water (the undesired side reaction) is mostly influenced by properties of the catalyst surface.

"Now that we understand what's happening on the surface, we can start pushing towards rational catalyst design," Wilson said. The research group is now looking into another catalyst, gold-palladium, which has been shown in previous work to be very selective towards H2O2. "People still don't entirely know why gold-palladium is so selective," Wilson added, but it seems that this new mechanistic insight will help to explain the selectivity of these materials.

Several students in Flaherty's lab are currently exploring different ways of "coupling this chemistry directly with reactions that use hydrogen peroxide for green oxidations within very short length scales," that is, micrometers away, Flaherty said. "If we can put these H2O2 formation catalysts very close to something which performs the oxidation reaction, we can avoid the entire problem or concentrating and transporting hydrogen peroxide."

David Flaherty | EurekAlert!

More articles from Materials Sciences:

nachricht Pressure tuned magnetism paves the way for novel electronic devices
18.12.2018 | Bar-Ilan University

nachricht Researchers observe charge-stripe crystal phase in an insulating cuprate
18.12.2018 | Boston College

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data storage using individual molecules

Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.

Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Pressure tuned magnetism paves the way for novel electronic devices

18.12.2018 | Materials Sciences

New type of low-energy nanolaser that shines in all directions

18.12.2018 | Physics and Astronomy

NASA research reveals Saturn is losing its rings at 'worst-case-scenario' rate

18.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>