钛硅分子筛的改性对环己烷氧化反应的影响

使用不同改性液H_2SO_4-H_2O_2、(NH_4)_2CO_3-H_2O_2、(NH_4)HF_2-H_2O_2和(NH_4)_2CO_3+(NH_4)HF_2-H_2O_2混合溶液对中空钛硅分子筛进行改性。采用XRD、UV-Vis和拉曼光谱进行表征分析,考察改性前后钛硅分子筛在环己烷氧化反应的催化性能。结果表明,改性过程没有破坏钛硅分子筛的MFI拓扑结构,但提高了钛硅分子筛相对结晶度,并脱除了部分锐钛矿相TiO_2;与未改性钛硅分子筛相比,环己醇和环己酮选择性及H_2O_2有效利用率明显提高,以改性液(NH_4)_2CO_3+(NH_4)HF_2-H_2O_2改性钛硅分子筛效果最佳,醇酮选择性提高12.78个百分点,H_2O_2有效利用率提高17.33个百分点;(NH_4)_2CO_3+(NH_4)HF_2-H_2O_2混合溶液改性钛硅分子筛显著降低H_2O_2用量,在己内酰胺生产过程中有很好的应用前景。

Effect of titanium silicalite modification on cyclohexane oxidation

Hollow titanium silicalite(HTS) was modified by different solutions ofH₂SO₄-H₂O₂、(NH₄)₂CO₃-H₂O₂,(NH₄)HF₂-H₂O₂ andNH₄)₂CO₃+(NH₄)HF₂-H₂O₂.The modified HTS samples were characterized by XRD,UV-Vis and Raman.The catalytic performance of HTS before and after modification for cyclohexane selective oxidation were investigated.The results showed that the modification of HTS did not destroy its topological structure of MFI,improved the relative crystallinity of HTS,and partial anatase TiO₂ was removed.Compared with the HTS,the selectivity to cyclohexanol and cyclohexanone,and the utilization rate ofH₂O₂ over modified HTS were improved obviously.HTS modified by the solution of(NH₄)₂CO₃+(NH₄)HF₂-H₂O₂ for cyclohexane selective oxidation exhibited optimal catalytic performance,and the selectivity to cyclohexanol and cyclohexanone was increased by 12.78 percentage point,the utilization rate ofH₂O₂ was improved by 17.33 percentage point;HTS modified by the solution of(NH₄)₂CO₃+(NH₄)HF₂-H₂O₂ remarkably decreased HH₂O₂ dosage,which had good application prospect in the process of caprolactam production.