氟化MCM-41催化性能的研究

用XRD考察不同含氟量的氟化MCM-41的结构变化,氟含量在5%以下时,无明显晶形变化,5%以上时出现新的物相(AlF2OH和AlF3);含氟达10%时,MCM-41晶形被破坏,新相生成和晶形破坏均不利于催化性能的改善。用FT-IR考察其吸附吡啶行为,表明MCM-41经氟化后,改变了表面酸性,随氟含量的增加,L酸位吸附峰减弱,B酸位吸附峰先增强后减弱,在氟含量为3%时为极大。以甲苯烷基化作为选择性研究的探针反应,考察了氟改性MCM-41对甲苯和异丙醇烷基化反应的催化性能,结果表明,氟含量为3%时有优良的活性和选择性,最佳的反应条件为:WHSV=0.85h-1,反应温度473K。

Studied on Catalytic Properties of F/MCM-41

Fluorinated MCM-41 (F/MCM-41) of various fluorine content was prepared and characterized by XRD and FT-IR. XRD patterns show that fluorine content is less than 5%, the phase of samples was unchanged. However, the phase of MCM-41 was broke with 10% of fluorine content, and grew up new phases (AlF2OH and AlF3). IR spectra of Pyridine adsorbed have been used to measure the acidities of F/MCM-41. It has been found that the acidities of F/MCM-41 was changed. When the fluorine content increases, Lewis acid sites decreases. Bronsted acid sites presents a maximum with 3% of fluorine content. Selectivity was studied by alkylation of toluene for the probe. Catalytic properties of F/MCM-41 for the alkylation of toluene with isopropanol were investigated. F/MCM-41 shows a high papa-isopropyltoluene selectivity when 3% of fluorine content. Reactive temperature 473 K and WHSV=0.85 h-1 were optimum.