National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Nanjing, 211111, China.
Center for Taihu Basin, Institute of Water Science and Technology, Hohai University, Nanjing, 211111, China.
Environ Sci Pollut Res Int. 2024 Apr;31(18):27318-27328. doi: 10.1007/s11356-024-32752-w. Epub 2024 Mar 20.
The presence of HCl and SO gas imposes limitations on syngas utilization obtained from household waste in a wide range of applications. The hydrotalcite-like compounds (HTLs) have been proved that could remove HCl efficiency. However, the research on impact of synthesis conditions of HTLs and SO on HCl removal was limited. In this study, a range of Ca-Mg-Al mixed oxide sorbents was synthesized by calcining HTLs, with variations in crystallization temperature, solution pH, and the Ca/Mg molar ratio. These sorbents were examined for their effectiveness in removing HCl at medium-high temperatures under diverse conditions. The adsorption performance of selected sorbents for the removal of HCl, SO, and HCl-SO mixed gas at temperature of 350 °C, 450 °C, and 550 °C, respectively, was evaluated using thermogravimetric analysis (TGA). It was observed that the HTL synthesis parameters significantly influenced the HCl adsorption capacity of Ca-Mg-Al mixed oxides. Notably, HTLs synthesized at 60 °C, a solution pH of 10-11, and a Ca/Mg ratio of 4 exhibited superior crystallinity and optimal adsorption characteristics. For individual HCl and SO removal, temperature had a minor effect on HCl adsorption but significantly impacted SO adsorption rates. At temperatures above 550 °C, SO removal efficiency substantially decreased. When exposed to a mixed gas, the Ca-Mg-Al mixed oxides could efficiently remove both HCl and SO at temperatures below 550 °C, with HCl dominating the adsorption process at higher temperatures. This dual-action capability is attributed to several mechanisms through which HTL sorbents interacted with HCl, including pore filling, ion exchange, and cation exchange. Initially, HCl absorbed onto specific sites created by water and CO removal due to the surface's polarity. Subsequently, HCl reacted with CaCO and CaO formed during HTL decomposition.
HCl 和 SO 气体的存在限制了家庭废物中合成气在广泛应用中的利用。水滑石类化合物（HTLs）已被证明可以有效地去除 HCl。然而，关于 HTLs 和 SO 对 HCl 去除的合成条件的影响的研究有限。在这项研究中，通过煅烧水滑石合成了一系列 Ca-Mg-Al 混合氧化物吸附剂，结晶温度、溶液 pH 值和 Ca/Mg 摩尔比有所不同。这些吸附剂在不同条件下中高温下去除 HCl 的效果进行了研究。通过热重分析（TGA）评估了选定的吸附剂在 350°C、450°C 和 550°C 下分别去除 HCl、SO 和 HCl-SO 混合气体的吸附性能。结果表明，HTL 合成参数对 Ca-Mg-Al 混合氧化物的 HCl 吸附容量有显著影响。值得注意的是，在 60°C、溶液 pH 值为 10-11 和 Ca/Mg 比为 4 条件下合成的 HTLs 表现出较高的结晶度和最佳的吸附特性。对于单独去除 HCl 和 SO，温度对 HCl 吸附的影响较小，但对 SO 吸附速率有显著影响。当温度高于 550°C 时，SO 的去除效率大大降低。当暴露在混合气体中时，Ca-Mg-Al 混合氧化物可以在低于 550°C 的温度下有效地去除 HCl 和 SO，HCl 在较高温度下主导吸附过程。这种双重作用能力归因于 HTL 吸附剂与 HCl 相互作用的几种机制，包括孔填充、离子交换和阳离子交换。最初，HCl 吸附在由于表面极性而由水和 CO 去除形成的特定位置上。随后，HCl 与 HTL 分解过程中形成的 CaCO 和 CaO 反应。
