含钛高炉渣合成多孔沸石分子筛及CO2吸附性能研究

Synthesis of porous zeolite molecular sieve using titanium-bearing blast furnace slag and its CO2 adsorption performance

摘要:

以钒钛磁铁精矿冶炼过程产生的含钛高炉渣为原料,经“酸处理-碱熔-水热晶化”步骤合成多孔沸石分子筛吸附剂。系统考察了偏铝酸钠添加量对多孔沸石分子筛结构的影响；采用动态吸附法评价了不同条件下所合成样品的CO₂吸附性能,并利用动力学模型进行数据拟合分析了其吸附行为。XRD、SEM、FTIR等表征结果证实,随着偏铝酸钠添加量的增加,水热晶化产物依次完成了由“无定形—初步结晶—FAU型—LTA型”沸石分子筛的结构转变。CO₂吸附实验结果显示,合成的Z-4样品经350 °C活化后,在25 °C条件下吸附效果最佳,其CO₂穿透和饱和吸附量分别可达2.16 mmol?g_-1^和3.39 mmol?g^_-1；且CO₂吸附行为符合拟二级动力学模型,吸附过程由物理和化学吸附共同主导,吸附速率可达4.709 mmol?g^_-1?s^_-1；经5次循环吸附/再生后,其CO₂饱和吸附量基本保持不变,展现出良好的循环稳定性。

Abstract:

Using titanium-containing blast furnace slag produced during the smelting process of vanadium titanium magnetite concentrate as raw material, porous zeolite molecular sieve adsorbent was synthesized by the step of "acid treatment-alkali melting-hydrothermal crystallization". The effect of sodium metaaluminate addition on the structure type of porous zeolite was investigated. Dynamic adsorption method was used to evaluate the CO₂ adsorption performance of the as-synthesized samples under different conditions, and the adsorption behavior was analyzed by data fitting with different kinetic models. The results of XRD、SEM、FTIR characterizations showed that the hydrothermal crystallization product in turn completed the transformation from “amorphous-preliminary crystallization-FAU type-LTA type” zeolite molecular sieve structure with the increase of sodium metaaluminate addition. The results of CO₂ adsorption experiments showed that the Z-4 sample activated at 350 °C exhibited excellent adsorption performance at adsorption temperature of 25 °C, with the CO₂ breakthrough and saturation adsorption capacities reaching 2.16 mmol?g_-1 ^{and 3.39 mmol?g}_-1^, respectively. The CO₂ adsorption behavior conformed to the pseudo-second-order kinetic model, and the adsorption was mainly physical and chemical adsorption, and the adsorption rate could reach 4.709 mmol?g_-1^?s_-1. After 5 regeneration cycles, the saturation adsorption capacity remained basically unchanged, showing a good cyclic stability.