Abstract:

Microporous-mesoporous hybrid Ti-MCM-41(H) was successfully synthesized by the nano-cluster assembling method. Gold nano-particles were prepared by the deposition-precipitation method. The samples were characterized by powder X-ray diffraction (XRD), nitrogen isothermal adsorption-desorption, Fourier transforminfrared (FT-IR) spectroscopy, diffuse reflectance UV-Vis (DR UV-Vis) spectroscopy, transmission electron microscopy (TEM) and inductively coupled plasma emission spectrometry (ICP-AES). The catalytic performance of the gold nano-particles was evaluated by the direct gas phase epoxidation of propylene using hydrogen and oxygen. Results revealed that the Ti-MCM-41(H) had a typical mesoporous MCM-41 structure. The results also suggested that isolated Ti(IV) was introduced into the siliceous framework of the support material. Superior catalytic performance was obtained with the gold catalyst supported on Ti-MCM-41(H) in which the Ti/Si molar ratio was 1%. Propylene conversion reached 5.4% at the initial 30 min with 74.2% propylene oxide (PO) selectivity and produced rate 73.1 g·h-1·kg-1. The conversion and PO selectivity were 4.9%and 67.3%after running 330 min on streamat 423 K.

Key words: Propylene epoxidation, Microporous-mesoporous hybrid zeolite, Nano-gold catalyst, Propylene oxide