金属掺杂TiO2催化剂制备及催化合成N-甲基氧化吗啉

Preparation of metal-doped TiO2 catalysts and their applications in synthesis of N-methylmorpholine-N-oxide

摘要:

以H2Ti3O7纳米线为前驱体，通过简单的离子交换和高温焙烧两步制备了具有不同金属掺杂的yM/TiO2催化剂（M=Fe, Co, Ni，y=0.25%，0.75%，1.25%，1.75%，2.25%）。通过XRD、SEM、TEM、XPS对催化剂进行了表征，结果显示掺杂的金属元素均匀分散到制备的TiO2纳米线基体表面，yM/TiO2催化剂形貌为纳米线/纳米棒，金属离子的掺入造成TiO2晶体结构中局部晶格扭曲导致催化剂表面形成较多的氧空位，提升了催化活性。考察了yM/TiO2催化剂在以H2O2为氧化剂催化氧化N-甲基吗啉（NMM）合成N-甲基氧化吗啉（NMMO）反应中的催化性能，结果表明，当掺杂的金属Fe含量为1.75%时，催化剂表面缺陷氧含量高达16.86%，催化性能最佳，在反应温度为35 ℃、反应3 h后NMMO产率达到97.5%。

Abstract:

Using H2Ti3O7 nanowires as precursors, yM/TiO2 catalysts（M=Fe, Co, Ni, y = 0.25%, 0.75%, 1.25%, 1.75%, 2.25%）with different metal-doped were prepared by simple ion exchange and high temperature calcination. yM/TiO2 catalysts were characterized by XRD, SEM, TEM and XPS. The results showed that the doped metal elements were evenly dispersed on the surface of the prepared TiO2 nanowire matrix. The morphology of yM/TiO2 catalysts were nanowire/nanorod. The incorporation of metal ions caused the distortion of local lattice in the TiO2 Crystal structure, resulting in the formation of more oxygen vacancies on the catalyst surface and improved the catalytic activity. The catalytic performance of yM/TiO2 in the synthesis of N-methylmorpholine (NMM) to N-methylmorpholine-N-oxide (NMMO) with H2O2 as oxidant was investigated. The results showed that when the doped metal Fe content was 1.75%, the surface defect oxygen content of the catalyst was as high as 16.86%, and the catalytic performance was the best. The yield of NMMO reached 97.5% after reaction at 35 ℃ for 3 h.