Vikrant Kumar, Kim Ki-Hyun, Dong Fan, Heynderickx Philippe M, Boukhvalov Danil W
Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 04763, Republic of Korea.
Department of Civil and Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 04763, Republic of Korea.
J Hazard Mater. 2022 Jul 15;434:128857. doi: 10.1016/j.jhazmat.2022.128857. Epub 2022 Apr 8.
Under dark/low temperature (DLT) conditions, the oxidative removal of gaseous formaldehyde (FA) was studied using eggshell waste supported silver (Ag)-manganese dioxide (MnO) bimetallic catalysts. To assess the synergistic effects between the two different metals, 0.03%-Ag-(0.5-5%)-MnO/Eggshell catalysts were prepared and employed for DLT-oxidation of FA. The steady-state FA oxidation reaction rate (mmol g h), when measured using 100 ppm FA at 80 °C (gas hourly space velocity (GHSV) of 5308 h), varied as follows: Ag-1.5%-MnO/Eggshell-R (9.4) > Ag-3%-MnO/Eggshell-R (8.1) > Ag-1.5%-MnO/Eggshell (7.5) > Ag-5%-MnO/Eggshell-R (7.2) > Ag-1.5%-MnO/CaCO-R (6.8) > MnO-R (6) > Ag-0.5%-MnO/Eggshell-R (3.2) > Ag/Eggshell-R (2.6). (Here, 'R' denotes hydrogen-based thermochemical reduction pretreatment.) The temperature required for 90% FA conversion (T) at the same GHSV exhibited a contrary ordering: Ag/Eggshell-R (175 °C) > Ag-0.5%-MnO/Eggshell-R (123 °C) > Ag-5%-MnO/Eggshell-R (113 °C) > MnO-R (99 °C) > Ag-1.5%-MnO/Eggshell (96 °C) > Ag-3%-MnO/Eggshell-R (93 °C) > Ag-1.5%-MnO/Eggshell-R (77 °C). The eggshell catalyst outperformed the ones made of commercial calcium carbonate due to the presence of defects in the former. The MnO co-catalyst enhances the catalytic activities through the capture and activation of atmospheric oxygen (O) with rapid catalytic regeneration. Also, MnO favorably captures the hydrogen of the adsorbed FA molecules to make the oxidation pathway thermodynamically more favorable.
在黑暗/低温（DLT）条件下，使用蛋壳负载银（Ag）-二氧化锰（MnO）双金属催化剂研究了气态甲醛（FA）的氧化去除。为了评估两种不同金属之间的协同效应，制备了0.03%-Ag-(0.5-5%)-MnO/蛋壳催化剂，并将其用于FA的DLT氧化。当在80℃（气体时空速度（GHSV）为5308 h⁻¹）下使用100 ppm FA进行测量时，稳态FA氧化反应速率（mmol g⁻¹ h⁻¹）变化如下：Ag-1.5%-MnO/蛋壳-R（9.4）> Ag-3%-MnO/蛋壳-R（8.1）> Ag-1.5%-MnO/蛋壳（7.5）> Ag-5%-MnO/蛋壳-R（7.2）> Ag-1.5%-MnO/CaCO₃-R（6.8）> MnO-R（6）> Ag-0.5%-MnO/蛋壳-R（3.2）> Ag/蛋壳-R（2.6）。（此处，“R”表示基于氢的热化学还原预处理。）在相同GHSV下90% FA转化所需的温度（T）呈现相反的顺序：Ag/蛋壳-R（175℃）> Ag-0.5%-MnO/蛋壳-R（123℃）> Ag-5%-MnO/蛋壳-R（113℃）> MnO-R（99℃）> Ag-1.5%-MnO/蛋壳（96℃）> Ag-3%-MnO/蛋壳-R（93℃）> Ag-1.5%-MnO/蛋壳-R（77℃）。由于蛋壳催化剂存在缺陷，其性能优于由商业碳酸钙制成的催化剂。MnO助催化剂通过捕获和活化大气中的氧气（O₂）以及快速的催化再生来提高催化活性。此外，MnO有利于捕获吸附的FA分子中的氢，使氧化途径在热力学上更有利。
