Preparation and CO2 adsorption performance of a phosphine-containing porous organic polymer supported magnesium oxide
MgO adsorbent has been widely used in the field of CO2 adsorption due to its advantages of low cost,wide source and low regen-erative energy consumption,but its adsorption performance is limited by its low surface ratio.In this paper,a phosphine-containing porous organic polymer POL-PPH3 with high surface area and hierarchical pore structure was used as a carrier,and POL-PPH3-loaded MgO ad-sorbent(MgO/POL-PPH3)was prepared by impregnation-calcination and ultrasonic calcinations to obtain the MgO adsorbent(MgO/POL-PPH3)for CO2 capture.Effects of preparation conditions such as preparation method,calcination temperature and calcination time on the CO2 adsorption performance on MgO/POL-PPH3 adsorbents were investigated.It is found that the impregnation calcination method is superior to the ultrasonic calcination method,and the CO2 adsorption capacity on the MgO/POL-PPH3 samples gradually decreases with the increase of calcination temperature and calcination time.The optimum CO2 adsorption capacity of 0.55 mmol/g on MgO/POL-PPH3-300-1 adsorbent is obtained when the impregnation calcination method is used with a calcination temperature of 300 ℃ and a calcination time of 1 h.In the simulated flue gas with a composition of 12％CO2 and the rest of nitrogen,the CO2adsorption capacity of 0.02 mmol/g on the MgO/POL-PPH3-300-1 adsorbent is obtained.Under the conditions of adsorption at 200 ℃ for 60 min and desorption at 370 ℃ for 15 min,the CO2 adsorption capacity of this adsorbent remains unchanged after five times of stable recycling.The structure-property re-lationship of CO2 adsorption on MgO/POL-PPH3 adsorbent was elucidated by combining N2 physical adsorption,thermogravimetric,FT-IR,XRD,SEM-EDX and other characterization methods.Kinetic modelling analysis of the CO2 adsorption behaviours on the three adsor-bents obtained at different calcination temperatures by impregnation calcination method is dominated by physical adsorption,whereas those of the three adsorbents obtained at different calcination times,including the MgO/POL-PPH3-300-1 adsorbent,are dominated by chem-ical adsorption.The high specific surface area and hierarchical pore structure are conducive to the exposure of more active sites and the transport and diffusion of CO2,which in turn increases the CO2 adsorption capacity of the MgO/POL-PPH3 adsorbent,and the high dis-persion of MgO on the support is also benificial to the enhancement of the contact with CO2 to accelerate the CO2 adsorption rate.
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