Industrial Solid Waste Derived SiO₂ As Support For Synthesizing Amine Functional Adsorbents Used For CO₂ Capture And Its Mechanism

In China,the production of fly ash,coal gangue,iron blast furnace slag,SiCl₄,and other silicic industrial solid waste are huge,howerver,the comprehensive utilization rate is still low,this not only causes serious environmental pollution,but also leads to the waste of resources.To develop high-end resource recovery of silicic industrial solid waste is conformation to the policies of our country,and is an important way for realizing the reduction of silicic industrial solid waste.This study attempted to utilize silicic industrial solid waste based SiO₂ as support for preparing amine functional CO₂ adsorbents and used for CO₂ capture from simulated flue gas,through a series of research,we mainly obtained the following research results:Amorphous silica is a good support for amine functional adsorbents sysnthesis,the pores locating in the pore size ranging from 2 nm to 40 nm in amorphous silica play a key role in amine functional adsorbents preparation process;utilizing wet impregnation method to prepare amine functional adsorbents,the loading amount of polyethyleneimine?PEI?,adsorption temperature,CO₂ partial pressure,and molecular structure and weight of PEI all influence the adsorption performance of amine functional adsorbents;under a loading amount of 60 wt.%of branched polyethyleneimine?BPEI?with 1200 Da could obtained adsorption capacity of 180 mg g^-11 or 114 mg g^-1 at 105^oC and 100%CO₂ or 15%CO₂,respectively,meanwhile the BPEI of 1200 Da could provide a good themal stability for amine functional adsorbents,therefore the BPEI of 1200 Da is a desirable choice for preparing amine functional adsorbents.The inactivation of amine functional adsorbents could be devided into physical inactivation and chemical inactication,chemical inactivation derived frome the formation of urea linkages betweem amine functional adsorbents and CO₂;physical inactivation dereived from the loss of organic amine molecules and the formed urea linkages inhibite the interaction of remained amine sites with CO₂;temperature obviously influences the chemical dynamics of urea linkages formation,and at 95^oC,115^oC,and 121^oC,the formation rate of urea linkages would obviously increase,and 121^oC is a key temperature for urea formation;furthermore,temperature also influences the structure of urea linkages.Water vapor in flue gas could inhibite the formation of urea linkages,but also could potentially increase the leaching of PEI molecules;10%O₂ could obviously oxidate the BPEI,but has no oxidation effect on linear polyethyleneimine?LPEI?;200 ppm NO has no influence on amine functional adsorbents;however,200 ppm NO₂ would seriously degradate amine functional adsorbents,but when the NO₂ concentration decreases to 10ppm,the degradation effects would obviously decrease;200 ppm SO₂ has serious degradation effects on amine functional adsorbents,and even if the concentration of SO₂decreases to 10 ppm,it also has obvious degradation effects on amine functional adsorbents,thus inhibiting the degradation effects of SO₂ on amine functional adsorbents would be a key scientififc problem for promting the practical industrial application of amine functional adsorbents.