A different method of creating ammonia was discovered by researchers from the University of Utah. The new method uses enzymes derived from nature, which generate ammonia at room temperature, as well as a small electrical current.
The research documenting this new technique was published Feb. 3 in the journal Angewandte Chemie International Edition.
New Process Of Ammonia Production
Almost a century ago, the Nobel Prize in Chemistry was awarded to Fritz Haber, the German chemist who managed to create ammonia from hydrogen and nitrogen gas. Back then, the method — which is still employed today — revolutionized agriculture. However, this process is very costly, as producing ammonia through this technique accounts for approximately 1 percent of the worldwide energy.
The researchers have only managed to produce a small quantity of ammonia so far. However, this new technique could significantly reduce the energy needed to produce ammonia, which is a substance used globally as a fertilizer in agriculture.
Ammonia is made of one atom of nitrogen and three atoms of hydrogen. Because of the very strong bond holding two nitrogen atoms together, researchers have to find a way of breaking it, either by reducing the nitrogen or by adding protons and electrons.
"Enzymatic fuel cells (EFCs) are devices that utilize redox enzymes as bioelectrocatalysts at anodic and cathodic electrode surfaces. Such devices can operate at room temperature, ambient pressure, and near-neutral pH, all of which are highly desirable for alternative NH3production," noted the research.
For the gaseous nitrogen to be transformed to ammonia, a fixation process is necessary, and it can be carried out through multiple methods. One of these processes involves an enzyme named nitrogenases. Nitrogenases are the only enzymes we know to turn nitrogen into ammonia. However, they are rarely subjected to scientific research, as nitrogenases can only be manipulated in an environment lacking oxygen, and they are also commercially unavailable.
The researchers created a fuel cell system that cloned the fixation of nitrogen through hydrogenase and nitrogenase. The hydrogenase was obtained by one of the researchers' collaborators from the Instituto de Catalisis y Petroleoquimica, Spain. The enzyme facilitated the process of stripping the electrons from the hydrogen gas, allowing them to be employed in the reaction of reducing nitrogen.
"In vivo, turnover occurs when reduced Fe protein (presumably reduced by a flavodoxin) binds to the MoFe protein, and ATP-hydrolysis-coupled electron transfer (ET) of a single electron between the two proteins takes place according to the balanced Equation," also noted the research.
The cell is made of two distinct compartments, which are interconnected through carbon paper electrodes. In the first cell, the hydrogen gas is oxidized by the electrons and hydrogenase, while in the second one, the electrons are put together with nitrogen through nitrogenase to produce ammonia.
Because the electrons move via a circuit, their movement creates current, and it produces a small quantity of power through the reaction.
Overcoming Challenges
Further research will have to be carried out before the researchers' process will be fit to be applied on an industrial level. One of the challenges of future approaches will have to address nitrogenase and its sensitivity, while another is in regard to ATP, a chemically expensive source of energy that contributes to the nitrogen fixation.
