A review on titanosilicate-1 (TS-1) catalysts: Research progress of regulating titanium species

Titanosilicate-1 (TS-1) has attracted extensive attention of researchers due to its unique shape-selective catalytic oxidation performance and excellent hydrothermal stability. However, the diffusion restriction and acid site restriction inside the molecular sieve will hinder the further industrial application of TS-1. Therefore, some modifications are needed to eliminate the influence of these two limitations. At present, although the methods of weakening or even eliminating diffusion restrictions are very mature, there is still some room for exploration due to the complex internal environment of TS-1 and the specific reaction mechanism. This paper comprehensively discussed the influence of the optimization of synthesis conditions on improving the content of framework Ti species and inhibiting the formation of non-framework Ti species. The methods for regulating the distribution, the electronic environment and the coordination states of Ti species were summarized, and the specific methods for eliminating non-framework Ti species after treatment were compared and analyzed.