Ultrafast synthesis of TS-1 without extraframework titanium species in a continuous flow system

Abstract

When preparing porous crystalline materials, low energy utilization and long crystallization times (∼48 h) as well as the instability of the products makes it difficult for traditional hydrothermal technology using batch reactors to meet the ever increasing environmental requirements of the chemical industry. However, rapid crystallization can be realized when using a continuous flow system such as a tubular reactor due to large heat transfer coefficient. Herein, we demonstrate the rapid continuous hydrothermal synthesis of nanoparticles of TS-1 with a tubular reactor. The particles have MFI structures and a very narrow size distribution of 100–150 nm after an 8 min synthetic step in tubes with an inner diameter of 2 mm and an external diameter of 3 mm. The results show that a faster nucleation rate improved the proportion of titanium entering into the silicon skeleton, with almost all Ti species existing in the tetrahedral coordination state at a grain size of 42 nm. This simple and intrinsically safe route allows good quality control and high productivity with very little equipment, and allows for easy scale-up. This first case of fast synthesis of TS-1 may provide some valuable references for the development of green synthesis of much more crystalline materials.