Synthesis and Low-Temperature CO2 Capture Properties of a Novel Mg-Zr Solid Sorbent

Mesoporous Mg-Zr solid solutions with different nominal Mg/Zr atomic ratios (0, 0.25, 0.5, 0.75, 1) were synthesized by a coprecipitation method, and the performance of CO2 adsorption/desorption was studied in a fixed-bed reactor under different conditions. In the synthesis process, Mg2+ was introduced successfully into the ZrO2 lattice and formed a maximum number of new Mg-O-Zr basic sites at Mg/Zr = 0.5. The CO2-temperature-programmed desorption (TPD) results showed the basic strength of the basic sites was Zr-O-Zr < Mg-O-Zr < Mg-O-Mg and the relatively weak basic strength of Mg-O-Zr was a benefit for regeneration of the sorbent. In the process of adsorption, high surface area (269 m(2)/g) and pore volume (0.63 m(3)/g) as well as appropriate basic sites of Mg-O-Zr made the Mg-Zr solid sorbent increase CO2 adsorption capacity by more than 5 times compared to pure MgO. The CO2 adsorption capacity of the sorbent increased in the presence of water vapor. Typically, the CO2 capacity of Mg-Zr solid sorbent had a maximum CO2 capture of 1.28 mmol/g at 30 degrees C without water vapor and 1.56 mmol/g sorbent under 10 vol % moist conditions at 60 degrees C, respectively. Results of a reutilization test suggested that the sorbent was stable for cyclic adsorption.