A low cost catalyst could allow the US Navy to use seawater as feedstock for fuel.
US Researchers from academia and industry have demonstrated that a potassium-promoted molybdenum carbide catalyst can efficiently and reliably use seawater as a feedstock for fuel. This process could allow the US Navy to eliminate the need for traditional refuelling operations.
The catalyst, which has been demonstrated to convert carbon dioxide to carbon monoxide, a critical step in turning seawater into fuel, was developed by the Porosoff research group at the University of Rochester, along with researchers at the Naval Research Laboratory, the University of Pittsburgh and OxEon Energy.
Publishing their work in the journal Energy & Environmental Science, Marc Porosoff, assistant Professor in the Department of Chemical Engineering at Rochester University said ‘This is the first demonstration that this type of molybdenum catalyst can be used on an industrial scale.’
During 2014 a Naval Research Laboratory team announced that it had used a catalytic converter to extract carbon dioxide and hydrogen from seawater; converting the gases into liquid hydrocarbons at a 92% efficiency rate. Since that time the focus has been on increasing the efficiency of the process and scaling up to produce sufficient quantities of fuel.
Currently it is very difficult to take carbon dioxide extracted from seawater and convert it directly into liquid hydrocarbon. For this reason it is necessary to convert the carbon dioxide into carbon monoxide using the reverse water-gas shift reaction (RWGS). The carbon monoxide can then be converted into liquid hydrocarbons via Fischer-Tropsch synthesis.
The research team explains that typically catalysts for RWGS require expensive precious metals that deactivate rapidly under reaction conditions. However, the potassium-modified molybdenum carbide catalyst is made from low-cost components and didn’t show any signs of deactivation during the continuous operation of the 10-day pilot-scale study. Potassium lowers the energy barrier associated with the RWGS reaction.
The research team will also investigate if the potassium-promoted molybdenum carbide catalyst might also be useful for capturing and converting carbon dioxide from power plants. The study will focus on testing the catalyst’s stability when exposed to common contaminants found in flue gas such as mercury, sulphur, cadmium and chlorine.