Role of Recrystallization in Alkaline Treatment on the Catalytic Activity of 1-Butene Epoxidation

Two alkylol amines, which were ethanolamine (EOA) and triethanolamine (TEOA), were used to posttreat nanosized titanium silicalite-1 (TS-1) to improve its catalytic activity for 1-butene epoxidation. Comparative studies were conducted to clarify the influences of the EOA and TEOA concentrations on the physicochemical properties through detailed characterization. EOA treatment can dissolve the framework Si, [SiO₄], on the external surface of TS-1, generating some macropores. TEOA serves as structure-directing agent to form MFI topology other than the dissolution of [SiO₄], and promotes the recrystallization of [SiO₄], forming new TS-1 particles over the external surface. The two treatments can both improve the catalytic activity of 1-butene epoxidation, but the samples treated with TEOA exhibit better catalytic stability. This can be attributed to the characteristic recrystallization of [SiO₄] in the case of TEOA treatment, stabilizing the structure of TS-1 and maintaining more framework Ti and intercrystal space.