Environmentally friendly rockets

May 27, 2011

(PhysOrg.com) -- Many rockets, satellites, and spacecraft are driven by hydrazine, sometimes with an oxidizing agent like nitric acid or dinitrogen tetroxide. When filling tanks with these highly toxic substances, technicians must wear full protective clothing—and a failed launch can lead to significant environmental damage. Researchers are thus looking for alternatives that are more environmentally friendly and less toxic, but just as powerful—requirements that are hard to meet in a single material.

Stefan Schneider and his co-workers at the Air Force Laboratory (Edwards Air Force Base, USA) have now introduced a new approach in the journal Angewandte Chemie: special hydrogen-rich ionic liquids that self-ignite in the presence of peroxide.

Despite the potential danger, hydrazine is used as a rocket fuel because it delivers high performance, can be stored for a relatively long time, and spontaneously ignites upon contact with an or a suitable catalyst. The oxidizing agents used as fuels are also dangerous. Dinitrogen tetroxide is less corrosive than nitric acid, but it is toxic and highly volatile. Hydrogen peroxide is a promising alternative because it is less corrosive and leads to much less toxic gas at room temperature. Its decomposition produces only water and oxygen.

As an alternative to hydrazine as a fuel component, Schneider and his co-workers propose an ionic liquid. Ionic liquids are compounds that consist of ions, namely positive and negatively charged particles, like a salt. However, they are not crystalline; they remain “molten” as a liquid at room temperature. Ionic liquids essentially do not vaporize, which prevents the formation of toxic vapors. It has previously not been possible to produce an ionic liquid that is flammable when partnered with hydrogen peroxide.

Schneider and his team have now overcome this barrier. The positively charged ion of their ionic liquid is a phosphorus atom bound to four hydrocarbon chains. At the core, however, lies the negatively charged ion made from one aluminum, four boron, and sixteen hydrogen atoms. The hydrogen-rich composition raises the power of the fuel component. “This aluminum borohydride ion can be viewed as a densified form of hydrogen stabilized by metal atoms. In fact, for a given tank size, liquids with this ion contain even more hydrogen than pure liquid hydrogen, without the difficult cooling requirements,” according to Schneider.

In order to test the ignitibility, the researchers applied drops of the novel ionic liquid onto various oxidizing agents. Upon contact with hydrogen peroxide, ignition was nearly instant; with fuming nitric acid it exploded. Says Schneider: “It is thus interesting as a potential component for greener high-performance fuels.”

Explore further: Recycling industrial waste water: Scientists discover a new method of producing hydrogen

More information: Stefan Schneider, Green Bipropellants: Hydrogen-Rich Ionic Liquids that Are Hypergolic with Hydrogen Peroxide, Angewandte Chemie International Edition, dx.doi.org/10.1002/anie.201101752

Related Stories

Scientists demonstrate novel ionic liquid batteries

Apr 15, 2011

(PhysOrg.com) -- Scientists at the NRL Materials Science and Technology Division are providing solid evidence that there is a new route towards developing novel, lightweight energy storage devices. By moving ...

The Future in Two Words: Ionic Liquids

Nov 13, 2009

(PhysOrg.com) -- Ionic liquids are molecular solutions that have a wide range of potential applications, including next-generation solar cells, hydrogen fuel cells and lithium batteries.

Data Effort Improves Flow Toward 'Greener' Chemistry

Apr 21, 2005

Jeopardy answer: Death Valley and "ionic liquids." Correct question: Where does a little bit of water make a whole lot of difference? Scientists at the National Institute of Standards and Technology (NIST) rep ...

Ionic Liquid's Makeup Measurably Non-Uniform at the Nanoscale

Nov 10, 2009

(PhysOrg.com) -- Researchers at Texas Tech University, Queen's University in Belfast, Ireland, the University of Rome and the National Research Council in Italy recently made a discovery about the non-uniform chemical compositions ...

Scientists develope new agents to battle MRSA

Mar 25, 2009

Experts from Queen's University Belfast have developed new agents to fight MRSA and other hospital-acquired infections that are resistant to antibiotics. The fluids are a class of ionic liquids that not only kill colonies ...

Recommended for you

A greener source of polyester—cork trees

Apr 16, 2014

On the scale of earth-friendly materials, you'd be hard pressed to find two that are farther apart than polyester (not at all) and cork (very). In an unexpected twist, however, scientists are figuring out ...

A beautiful, peculiar molecule

Apr 16, 2014

"Carbon is peculiar," said Nobel laureate Sir Harold Kroto. "More peculiar than you think." He was speaking to a standing-room-only audience that filled the Raytheon Amphitheater on Monday afternoon for the ...

Metals go from strength to strength

Apr 15, 2014

To the human hand, metal feels hard, but at the nanoscale it is surprisingly malleable. Push a lump of metal with brute force through a right-angle mould or die, and while it might look much the same to the ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

that_guy
5 / 5 (1) May 27, 2011
I want to know how this compares with standard rocket fuel. Is it more powerful, less powerful, or about the same?

With little or no vapor pressure, and liquid at room temperature, there's a lot of cooling equipment/insulation/venting equipment/etc that you won't need - essentially the difference between a $3000 hydrogen tank and a $100 gas tank.

The potential of this kind of rocket fuel goes far beyond environmental concerns.

More news stories

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

Leeches help save woman's ear after pit bull mauling

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...