论文部分内容阅读
用三甲基氯硅烷、二甲基二氯硅烷、甲基三氯硅烷、四氯化硅与甲基碘改性高硅MCM-41中孔分子筛.XRD,~(29)Si MAS NMR,~(13)C CP MAS NMR,以及N_2、水与环己烷吸附的表征,显示改性不同程度地改变了分子筛的表面组成与结构,减小孔径,增加孔壁厚度,因而影响吸附行为,减小吸附容量.硅烷化减少了MCM-41的表面硅羟基含量,增加其疏水性.用CH_3I改性使孔径减小1.4nm,而硅羟基含量并未显著减少.硅烷化以及用CH_3I改性可提高MCM-41分子筛的热稳定性.SiCl_4的改性作用相对不明显.样品的水及环己烷吸附容量与其表面硅羟基含量呈现不同的线性关系,揭示高硅MCM-41分子筛表面吸附中心的本性.
MCM-41 mesoporous molecular sieves modified with trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, silicon tetrachloride and methyl iodide.XRD, ~ (29) Si MAS NMR, ~ (13) C CP MAS NMR, and the characterization of N 2, water and cyclohexane adsorption showed that the modification changed the surface composition and structure of molecular sieve to some extent, decreased the pore size and increased the pore wall thickness, thus affecting the adsorption behavior Silanization reduced the content of silanol groups on the surface of MCM-41 and increased its hydrophobicity.The pore size was reduced by 1.4nm with the modification of CH_3I, but the silanol content did not decrease significantly.Silanization and modification with CH_3I Improve the thermal stability of MCM-41 molecular sieve .SiCl_4 modification is relatively insignificant .Samples of water and cyclohexane adsorption capacity and its surface silanol content showed a different linear relationship, revealing high silica MCM-41 zeolite adsorption center nature.