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Safety of Ammonia As Hydrogen and Energy Carriers
Presentation

Safety of Ammonia As Hydrogen and Energy Carriers

Yoshitsugu Kojima

Ammonia (NH3) is liquefied at 1 MPa and 25 °C, and has a highest volumetric hydrogen density of 10.7 kg H2 /100L. It has a high gravimetric hydrogen density of 17.8 wt%. The heat of formation of NH3 is about 1/10 of combustion heat of hydrogen. NH3 has advantages as a hydrogen carrier for fuel cell vehicles and an energy carrier for power plants. In this research, the purpose is to figure out regulations for safety of NH3 in the world, and survey NH3 accident. We also characterize water as a NH3 absorbent. Regulations for flammability and health hazard are…

Presentation

Proton-Based Solid Acid for Ammonia Removal

Masakuni YamaguchiTomoyuki IchikawaHikaru MiyaokaKeita NakajimaTengfei ZhangHiroki MiyaokaYoshitsugu Kojima

Large amount of water is a NH3 absorbent in the plant facilities for emergency. NH3 and NH4+ coexist in ammonia water. For example, potential of hydrogen (pH) is 11 in 2500 ppm ammonia water and the ratio of NH3 and NH4+ are 98% and 2%, respectively. The aqueous solution releases NH3 due to the high equilibrium vapor pressure, resulting in increase of the negative effects on the environment. Therefore, in order to reduce ammonia released to the atmosphere, sulfuric acid is added in the aqueous solution. In this case, ammonium sulfate is formed and dissolves in the water. Therefore complicated…

Ammonia As a Hydrogen Carrier for PEM Fuel Cells
Presentation

Ammonia As a Hydrogen Carrier for PEM Fuel Cells

Yoshitsugu Kojima

Ammonia (NH3) is easily liquefied by compression at 1 MPa and 25°C, and has highest volumetric hydrogen density of 10.7 kg H2 /100L. It has high gravimetric hydrogen density of 17.8 wt%. The heat of formation of NH3 is about 1/10 of combustion heat of hydrogen. NH3 has advantages as a hydrogen carrier for fuel cell vehicles (FCVs). ISO 14687-2:2012 specifies the quality characteristics of hydrogen fuel. The maximum concentration of NH3 and N2 for the FCVs is 0.1ppm and 100 ppm, respectively. The minimum H2 purity is 99.97%. We need component technologies to produce high-purity hydrogen from ammonia, together…

Ammonia Storage Materials Using Metal Halides and Borohydrides
Presentation

Ammonia Storage Materials Using Metal Halides and Borohydrides

Yoshitsugu Kojima

Ammonia (NH3) is easily liquefied by compression at 1 MPa and 25 °C, and has a highest volumetric hydrogen density of 10.7 kg H2 /100L in hydrogen carriers. The volumetric hydrogen density is above 1.5 times of liquid hydrogen at 0.1 MPa and -253 °C. The vapor pressure of liquid NH3 is similar to propane. Moreover it has a high gravimetric hydrogen density of 17.8 mass%. NH3 is burnable substance and has a side as an energy carrier which is different from other hydrogen carriers. The heat of formation of NH3 is 30.6 kJ/molH2. The value is about 1/10 of…

Liquid Ammonia for Hydrogen Storage
Presentation

Liquid Ammonia for Hydrogen Storage

Yoshitsugu Kojima

Hydrogen storage and transportation technology is essentially necessary to realize hydrogen economy. Hydrogen can be stored in many different forms, as compressed or liquefied hydrogen in tanks, or as hydrogen carriers: a hydrogen-absorbing alloy, metal hydrides with light elements, organic hydrides and carbon-based hydrogen storage materials. Among them, solid-state hydrides with light elements such as MgH2, Mg(BH4)2 and NH3BH3 possess high hydrogen capacity, 7-20 mass%, However, the practical volumetric H2 density is below 8 kgH2/100L because the packing ratio is down to 50%. Ammonia is easily liquefied by compression at 1 MPa and 25°C, and has a high volumetric hydrogen…

A Green Ammonia Economy
Presentation

A Green Ammonia Economy

Yoshitsugu Kojima

Ammonia has a high volumetric hydrogen density of 107.3 kg H2 per cubic meter, because it is easily liquefied by compression below 0.86 MPa at 20° C. The vapor pressure of liquefied ammonia is similar to propane. Moreover it has a high gravimetric hydrogen density of 17.8 mass% compared with the solid state hydrogen storage materials. It is noteworthy that ammonia can be synthesized from hydrogen in large scale manufacturing by Haber–Bosch process at 400-600° C and 20-40 MPa. Therefore, liquid ammonia is one of the most promising methods for storing and transporting hydrogen. CO2 free hydrogen (ammonia) will be…