Development of novel absorbents for CO2 capture from blast furnace gas

In order to establish energy-saving technology for CO₂ capture from blast furnace gas, novel absorbents were developed in the laboratory and evaluated at a 1 t_CO2/d test plant. At first, CO₂ absorption and desorption behaviors of single-component amine solvents for simulated blast furnace gas (CO₂/N₂ = 20%/80%) were investigated through a screening test using a small scrubbing bottle. These amine solvents were additionally analyzed using nuclear magnetic resonance (¹³C NMR) spectroscopy and reaction calorimetry. The results of the laboratory experiments showed that there was a trade-off between absorption rate and enthalpy of absorption but some absorbents had unique features. For example, 2-isopropylaminoethanol (IPAE) had high absorption rate and small enthalpy of absorption. Then, new IPAE-based amine solvents (RITE solvents: RITE-A and RITE-B) were formulated and evaluated at the 1 t_CO2/d test plant. CO₂ regeneration energies of the RITE solvents were 3.3 and 3.1 GJ/t_CO2, respectively. With certain process conditions and plant specifications optimized, RITE-B was estimated to have the potential to achieve 2.5 GJ/t_CO2.     

Possible change in Asian dust source suggested by atmospheric anthropogenic radionuclides during the 2000s

Decades-long monitoring of anthropogenic radionuclides in the atmospheric deposition in Tsukuba, Japan suggests not only the substantial impacts of the Asian dust (Kosa) on the deposition but also the possible change of the Kosa source region, especially during springs of the 2000s. In order to know more about such change, 4 single wet deposition events occurred in the spring of 2007 were scrutinized. The largest anthropogenic radionuclides wet deposition was supplied by the April 2–4 event. It brought several tens % of the monthly depositions (April 2007) of the dust (residue) mass (4.5 g m^?2) and anthropogenic radionulides (⁹⁰Sr: 16, ¹³⁷Cs: 97 and Pu: 3 mBq m^?2). None of the events observed fulfilled both criteria of the specific activities and ⁹⁰Sr/¹³⁷Cs activity ratio to the Tsukuba soil; they did not exhibit local soil dust signature. The Kosa events in fact have extensive impacts on the atmospheric environment over Japan in spring season. Considering the elevated specific activities as well as greater ¹³⁷Cs/⁹⁰Sr activity ratio in the deposited dust, it is hypothesized that the dust source areas in Asian continent would be shifting from the arid zone to the desert-steppe zone suffering from desertification during the 2000s. This type of the Kosa may be called as the ‘new-regime Kosa’. Chemical observation in the far downwind region of the Kosa dust could allow us to know possible shift in the source regions.