Calcium precursor from stirring processes at room temperature for controllable preparation of nano-structure CaO sorbents for high-temperature CO2 adsorption

Abstract

Nano-structure CaO crystals with an average size of 480 nm × 255 nm (length and width) were prepared by simply roasting CaCO3 precursors at 900 °C for 2 h. The CaCO3 precursors with a pure vaterite crystalline phase were readily synthesized by a room temperature stirring method using Ca(NO3)2 and CO2 storage material (CO2SM). The CO2SM played an important role in providing CO32− source and structure controlling. The effects of CO2SM dosage, Ca2+ concentration, and stirring time on the crystallization of CaCO3 precursors were investigated. In addition, the CO2SM was successfully regenerated by simply exposing the filtrate from the preparation process to CO2 for further preparing CaCO3 precursor. The as-obtained CaO crystals exhibited a strong CO2 adsorption capacity up to 17.18 mmol g-1 under 0.1 MPa at 700 °C.