At present, two of the most significant challenges common to developed countries are taking steps to address climate change and translating into communities that use considerable amounts of renewable energy for power.
One propitious technology for achieving these involves the use of hydrogen (H
2) as a source of renewable energy. Despite the fact that hydrogen is a basic candidate for clean secondary energy, huge amounts of H 2 must be transformed into liquid form, which is a challenging procedure, for easier storage and transportation. Of the probable forms of liquid H 2, ammonia (NH 3) is a propitious carrier since it has a high density of H 2, can be easily liquefied, and can be synthesized on a large scale.
CuOx/3A2S selectively produces N2 and H2O from NH3 through a two-step reaction. (Image credit: Dr Satoshi Hinokuma)
Moreover, recently, NH
3 has been gaining attention as a carbon-free substitutive fuel. NH 3 is a combustible gas that can be largely applied in industrial furnaces and thermal power generation as a substitute for light oil and gasoline. However, it is hard to ignite (due to its high ignition temperature) and produces hazardous nitrogen oxides (NO x) at the time of combustion.
The focus of scientists from the
International Research Organization for Advanced Science and Technology (IROAST) in Kumamoto University, Japan, was on a “catalytic combustion method” to solve the NH 3 fuel challenges. This technique adds substances that suppress or promote chemical reactions at the time of fuel combustion.
In the recent past, the researchers were successful in creating an innovative catalyst that suppresses the production of NO
x and enhances NH 3 combustibility. The innovative catalyst (CuO x/3A 2S) is a mullite-type crystal structure 3Al 2O 3·2SiO 2 (3A 2S) carrying copper oxide (CuO x). When this catalyst was used to burn NH 3, scientists discovered that it remained highly active in the selective synthesis of N 2, implying that it suppressed the formation of NO x, and the catalyst did not change itself even at higher temperatures. Furthermore, they were successful in their in situ (Operando) observations during the CuO x/3A 2S reaction and refined the NH 3 catalytic combustion reaction mechanism.
Due to the fact that 3A
2S is a commercially available material and CuO x can be synthesized with the help of a technique largely used in industry (wet impregnation technique), this innovative catalyst is inexpensive and easy to produce. The use of this catalyst enables the disintegration of NH 3 into H 2 with the heat from (low ignition temperature) NH 3 fuel combustion, and the purification of NH 3 by means of oxidation.
Our catalyst appears to be a step in the right direction to fight anthropogenic climate change since it does not emit greenhouse gasses like CO 2 and should improve the sophistication of renewable energy within our society. We are planning to conduct further research and development under more practical conditions in the future.
Dr. Satoshi Hinokuma of IROAST, Study Leader
This study was published online on March 26, 2018
, in the Journal of Catalysis.