Nanoscale Tungsten Carbide is Expected to be the Protagonist of the Rocket Catalyst

At 12:50 on November 21st, our new generation launch vehicle, long march six, was successfully launched at the Taiyuan satellite launch center. This is the first commercial launching mission of the long march six launch vehicle following the successful first flight in 2015. The launch was carried out in an arrow and Samsung way, successfully sending three "Jilin One" video satellites to the intended orbit.

Long march six uses liquid oxygen kerosene engine, which is non-toxic, pollution-free and green. Liquid oxygen kerosene is a typical hydrocarbon rocket propellant. In rocket propellants, whether it is liquid oxygen or liquid hydrogen or hydrazine, they can not be separated from a kind of important material, the catalyst, which is a kind of high performance, low cost, and the most promising catalyst material to replace platinum metal.

Engines for automobiles, planes and ships need not only fuel but also oxygen. And the launch vehicle to overcome the gravity of the flight to space, lift faster than the aircraft much faster than the aircraft, fuel efficiency must be very high, and have to work in super high altitude and outer space, the oxygen in the atmosphere is far from enough, so the rocket in addition to fuel, but also with oxidizing agent and catalyst.

Liquid oxygen kerosene is a typical hydrocarbon rocket propellant. It is also the main rocket fuel in recent years in China. Compared with liquid hydrogen fuel, the disadvantage of LOX kerosene is that it is relatively low in specific impulse and regenerative cooling capacity, and easy to accumulate carbon and coke. However, the combination of liquid oxygen / hydrocarbon propellant has many advantages, such as wide source, low cost, high combination density, high specific impact performance, non-toxic environmental protection and good storage resistance. It is understood that the use of liquid oxygen kerosene is 15 - 20% more than liquid hydrogen, which can greatly reduce the carrying of fuel, reduce the weight and volume of the rocket; and kerosene The price is low, which can save about 10000000 yuan per launch; kerosene and liquid oxygen are not toxic; combustion also produces only water and carbon dioxide, unlike the previous rocket engines that produce toxic pollution.

All the time, the spaceflight catalyst has been used as a platinum metal catalyst, the expensive price of platinum metals is not to be said much, and platinum metals will produce toxic substances during the catalytic process. However, the development of nanotechnology has opened up a new field of application for many materials. Tungsten carbide is one of the best. The presence of carbon in nano tungsten carbide has changed the electronic properties of tungsten surface, making it similar to platinum. Moreover, nano tungsten carbide will not produce toxic by-products.

It is found that the catalytic activity of tungsten carbide is mainly reflected in the catalytic activity of the carbon chain fracture reaction. The conversion rate of the catalytic active reactant increases with the increase of the reaction temperature. When oxygen is introduced, the catalytic activity of tungsten carbide decreases, but the selectivity to the reactant isomerization is introduced with the introduction of oxygen. At the same time, isomerization is the main reaction, which shows that tungsten carbide has a good catalytic effect on the liquid oxygen kerosene. Its surface composition has a direct effect on its catalytic activity and selectivity, and it needs to be doped with other elements to strengthen the effect. In short, tungsten carbide acts as the most active transition metal carbide and has Pt like characteristics in the catalytic isomerization of hydrocarbons.

The success of the first flight of the long march six launch vehicle marks a great breakthrough in the key technology of our country in the field of non-toxic and pollution-free launch vehicle, which is of great significance for improving our country's carrier rocket type spectrum and improving the ability to enter the space. In the future, China's space moon landing program is likely to use liquid oxygen kerosene propellants. And we also found that with the progress of science and technology, space applications are stepping into common business development step by step, air "taxi", space travel, nuclear fuel manned rocket, and lunar base, and human beings are turning scientific fantasy into possibility step by step. As for the application of tungsten, not only the catalyst, but also many excellent properties of tungsten will make it an indispensable material in the field of aerospace technology.

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