Jia He, Du Tao, Fang Xin, Gong He, Qiu Ziyang, Li Yingnan, Wang Yisong
State Environmental Protection Key Laboratory of Eco-Industry, School of Metallurgy, Northeastern University, Shenyang 110819, China.
ACS Omega. 2021 Jan 28;6(5):3961-3972. doi: 10.1021/acsomega.0c05842. eCollection 2021 Feb 9.
In this paper, a green synthesis method for ZSM-5 zeolite is explored to reduce the synthesis cost, environmental hazard, and reaction temperatures. For the ZSM-5 samples prepared at low temperatures, the influence of factors such as the hydrothermal temperature, crystallization time, and the number of seeds is systematically investigated. The adsorption isotherm of CO is used for fitting analysis of adsorption models and determination of the adsorption selectivity. The results show that the best one among the three samples presents the highest CO adsorption capacity of 2.39 mmol/g at 273 K and 15 bar. It is prepared with a hydrothermal temperature of 393 K, crystallization time of 7 days, and a seed crystal of 1 wt %. The dual-site Langmuir model can well describe the experimental data, indicating that double adsorption sites rather than the simple single-layer adsorption are dominant in samples. As the pressure increases, the adsorption capacity calculated by the model is much lower than the actual value with a deviation index of 12.5%. At a pressure of 1 bar, the optimal selectivity is attained with sample L-20, viz., CO/N of 34.3 and CO/O of 70.2. The green synthesis method reported in this research can be used to successfully prepare ZSM-5 zeolite, and it shows excellent CO adsorption performance. In addition, the use of low-cost raw materials and template-free synthesis methods will facilitate the large-scale application of green synthesis processes in the future.
本文探索了一种用于合成ZSM-5沸石的绿色方法，以降低合成成本、环境危害和反应温度。对于在低温下制备的ZSM-5样品，系统研究了水热温度、结晶时间和晶种数量等因素的影响。采用CO吸附等温线对吸附模型进行拟合分析并确定吸附选择性。结果表明，三个样品中性能最佳的样品在273 K和15 bar下的CO吸附容量最高，为2.39 mmol/g。它是在水热温度393 K、结晶时间7天和1 wt%晶种的条件下制备的。双位点朗缪尔模型能够很好地描述实验数据，表明样品中起主导作用的是双吸附位点而非简单的单层吸附。随着压力增加，模型计算的吸附容量远低于实际值，偏差指数为12.5%。在1 bar压力下，样品L-20的选择性最佳，即CO/N为34.3，CO/O为70.2。本研究报道的绿色合成方法可成功制备ZSM-5沸石，且其表现出优异的CO吸附性能。此外，使用低成本原料和无模板合成方法将有助于未来绿色合成工艺的大规模应用。
