柠檬酸改性ZSM-5分子筛的制备及VOCs吸附性能研究

Preparation of Citric Acid Modified ZSM-5 Molecular Sieve and Study on Its VOC Adsorption Performance

随着工业发展,挥发性有机化合物(VOCs)对环境的影响日益严重。分子筛在吸附VOCs方面表现优异,但在高湿度条件下,水蒸气与VOCs竞争吸附会降低吸附效果。为获得在高湿度下仍具有优异吸附性能的分子筛,使用柠檬酸对ZSM-5进行改性。研究表明:柠檬酸浓度影响改性分子筛的硅铝比和介孔参数,改性后的分子筛疏水性提高,当柠檬酸的浓度为3mol/L时,改性分子筛的比表面积最大,为484m^(2)/g,是初始比表面积的2.3倍。以挥发性有机化合物正己烷作为VOCs代表探针,与原始ZSM-5分子筛相比,在高湿度(85%)下,改性后分子筛饱和吸附量提升了1.4倍。循环测试表明,分子筛具有较好的循环稳定性。本研究为高湿度环境下VOCs的处理提供了参考。

With the development of industry,volatile organic compounds(VOCs)have a severe impact on the environment.Molecular sieves have a good adsorption effect on VOCs.However,under the conditions of high humidity,water vapor and VOCs cause adsorption competition,reducing the adsorption of VOCs.In order to obtain a molecular sieve with excellent adsorption performance under high humidity,a series of modified molecular sieves were prepared using citric acid to modify ZSM-5 in this paper.The effect of citric acid concentration on the silicon-to-aluminum ratio and mesoporous parameter properties of the modified molecular sieve was studied.The results showed that the hydrophobicity of the modified molecular sieve was improved.When the concentration of citric acid was 3 mol/L,the specific surface area of the modified molecular sieve was the largest at 484 m^(2)/g,which was 2.3 times the initial specific surface area.The volatile organic compound n-hexane was selected as a representative VOCs probe.Compared with the original ZSM-5 molecular sieve,the saturated adsorption capacity after modification increased by 1.4 times under high humidity(85%).Cyclic tests showed that molecular sieves had good cycle stability,which promoted the application and development of VOCs treatment materials under high humidity.