Creation of Innovative Technologies to Control Carbon Dioxide Emissions
  Development of Carbon-Neutral Energy Cycle by Highly Selective Catalysis
Our Goal

 We propose a new type of energy cycle without CO2 exhaust, that is, a Carbon neutral energy cycle (CN cycle) and have been investigating development of the CN cycle as a theme in the research area “Creation of Innovative Technologies to Control Carbon Dioxide Emissions”, JST-CREST since October 2010. With a mind to practical applications,three limitations are imposed on a CN cycle: (1) no CO2 emissions, (2) utilization of liquid fuels and (3) minimizing the use of precious metal catalysts. Possible
candidates for a CN cycle are the conversions of ethylene glycol (EG) to oxalic acid, ethanol to acetic acid, and ammonia to dinitrogen (or nitrate). In these systems, fuels are converted into carboxylic acids or dinitrogen (or nitrate), resulting in no CO2 emissions. As shown in Fig. 1, in the EG to oxalic acid cycle, we expect to produce ~80 % of the energy generated in complete combustion of ethylene glycol to CO2, which will satisfy the demands of current applications. Creation of highly selective oxidation catalysts, therefore, is the most important issue for realization of the CN cycle. Currently only precious metals can be applied to fuel cells constructed with acidic electrolytes, which is one of the reasons impeding the utilization of fuel cells in commercial applications. On the other hand, base metal catalysts can be applied as electrocatalysts in alkaline-type fuel cells. In anticipation of practical use in the near future, an alkaline-type fuel cell is adapted for the CN cycle. In our CREST project, base metal catalysts are being explored in combination with DFT calculations and detailed structural analysis using synchrotron radiation. Further, the fuels can be regenerated by reduction of the carboxylic acids or dinitrogen (or nitrate) with hydrogen produced from water using waste heat or sunlight, meaning less fossil fuels are consumed. We will produce novel nanometer-sized materials, which exhibit novel functionality, contributing to highly efficient and selective catalysis. The final goal of our research is the materialization of on-board energy systems without CO2 exhaust.