Mesoporous planar TS-1 supported molybdenum catalyst for green epoxidation of olefins: Synthesis, characterization and catalytic properties

Abstract

Catalytic epoxidation limitations of conventional ellipsoid titanosilicate-1 (TS-1) remains owing to the narrow microporous channels and low efficiency of the Ti species. Herein, two-dimensional planer TS-1 zeolite (TS-1-P) was synthesized by adding crystal growth regulator in the hydrothermal synthesis process, and then TS-1-P supported molybdenum (Mo/TS-1-P) and mesoporous Mo/TS-1-P (Mo/MTS-1-P) were prepared and applied in epoxidation of olefins. The TS-1-P and the modified TS-1-P catalysts show a similar MFI framework and grain morphology but the different pore structure and coordination environment of Ti or Mo species. Especially, the Mo/MTS-1-P possesses many mesoporous pore and highly dispersed Mo species, which can improve the coordination environment of Ti species and weaken the Ti-O bond, the results are beneficial for the framework Ti species to combine more easily with H₂O₂ to C=C band of the olefin molecules. Therefore, compared with TS-1-P, Mo/MTS-1-P exhibits the highest conversion of ACH (91.78 %) and 1-hexene (47.44 %) in the epoxidation of ACH and 1-hexene, respectively, the selectivity of epoxidized products simultaneous is above 96.42 % and 94.04 %, respectively. Moreover, the deactivation behavior of carbon deposit on the catalyst surface and regeneration method were also proposed. The successful preparation of Mo/MTS-1-P not only results in an efficient catalyst for epoxidation process but also provides a possible approach for surface and pore structure modification of TS-1 zeolite.