Synthesis of Highly Efficient CaO-Based, Self-Stabilizing CO₂ Sorbents via Structure-Reforming of Steel Slag

Abstract

Capturing anthropogenic CO2 in a cost-effective and highly efficient manner is one of the most challenging issues faced by scientists today. Herein, we report a novel structure-reforming approach to convert steel slag, a cheap, abundant, and nontoxic calcium-rich industrial waste, as the only feedstock into superior CaO-based, self-stabilizing CO2 sorbents. The CO2 capture capacity of all the steel slag-derived sorbents was improved more than 10-fold compared to the raw slag, with the maximum uptake of CO2 achieving at 0.50 gCO2 gsorbent(-1). Additionally, the initial steel slag-derived sorbent could retain 0.25 gCO2 gsorbent(-1), that is, a decay rate of only 12% over 30 carbonation-calcination cycles, the excellent self-stabilizing property allowed it to significantly outperform conventional CaO, and match with most of the existing synthetic CaO-based sorbents. A synergistic effect that facilitated CO2 capture by CaO-based sorbents was clearly recognized when Mg and Al, the most common elements in steel slag, coexisted with CaO in the forms of MgO and Al2O3, respectively. During the calcium looping process, MgO served as a well spacer to increase the porosity of sorbents together with Al2O3 serving as a durable stabilizer to coresist the sintering of CaCO3 grains at high temperatures.

Natural Calcium‐Based Sorbents Doped with Sea Salt for Cyclic CO2 Capture

“…Qin et al and Luo et al produced pelleted sorbents through extruded mixtures of calcium precursor and cements, and found better CO 2 capture during long‐term cycles; Sun et al further proposed biomass‐based pore‐forming technology to improve the pore structure of the extruded pellets, and to enhance their CO 2 absorption. Some researchers incorporated inert materials, such as, MgO , Ca 12 Al 14 O 33 , TiO 2 , CaZrO 3 , La 2 O 3 , Nd 2 O 3 , Ca 2 MnO 4 , and so on , , to improve the long‐term stability of sorbents. Yang et al and Gupta et al prepared high‐surface‐area precipitated calcium carbonate by using a wet precipitation process.…”

Use of steel slag for CO2 capture under realistic calcium-looping conditions

“…Expectedly, only CaO derived from the calcium-based compounds in the steel slag suffers carbonation under the CaL conditions applied, whereas the rest of the compounds remain inert, as shown in previous studies. 51,52 Fig. 1b illustrates the particle size distribution of the steel slag powder used in the experiments, with a volume weighed mean diameter of 106 mm.…”

Solid‐Waste‐Derived Carbon Dioxide‐Capturing Materials

“…[223][224][225][226][227] First, they studied the carbonation conversion performance of steel slag in simulated flue gas. [223][224][225][226][227] First, they studied the carbonation conversion performance of steel slag in simulated flue gas.…”

“…The resultant CO 2 sorbents achieved am aximum uptake CO 2 capacity of 11.3 mmol g À1 ,w hich was 10 times larger than that of the raw slag. [224] Moreover,s teel-slagderived Fe-functionalized CO 2 sorbents were used in the auto-thermalC O 2 sorptionp rocess. As shown in Figure 14 a, sorbents synthesized from steel slag showed ag reater recycling stability and reactivity than that of conventional CaO.…”