Nano CaO grain characteristics and growth model under calcination

This paper addresses the grain characteristics and growth model of nano CaO under high-temperature calcination conditions. Nano CaO samples derived from nano CaCO3 were prepared with a chamber calciner under different calcination times (10–480 min) and temperatures (750–900 °C) to study the nano CaO grain growth. X-ray diffractometer and the Scherrer formula were used to test and calculate the grain size of nano CaO. The microstructure and sorption performances of nano CaO were observed by a nitrogen adsorption/desorption apparatus and a thermogravimetric analysis. The results showed that the grain size of CaO grew faster as the calcination temperature increased. A growth asymptote was approached by prolonging the consecutive calcination time. A grain growth model for nano CaO was built according to solid phase sintering theory for the following conditions: 10–120 min isothermal calcination at 750–900 °C. The activation energy for nano CaO grain growth was calculated as 120 kJ/mol. In addition, the relation of grain growth, structural properties and CO2 adsorption performance of nano CaO are discussed.

► The size growth of nano CaO grain tested by XRD both for one cycle and multiple cylces.
► The growth model of nano CaO was derived as a function of calcination temperature and time.
► Specific surface area was explained by the combining the effects of the grain growth and the pore size distribution.
► The reactive sorption capacity of CaO was consistent with the specific surface area.