Supported Al–Ti bimetallic catalysts for 1-decene oligomerization: Activity, stability and deactivation mechanism

• CBAC support enables higher initial activity while γ-Al2O3 provides better stability.
• Thermal treatment reduces initial activity but improves stability.
• A linear relationship between PAO yield and chlorine content of catalyst was found.
• Deactivation of catalyst is due to deposition of oligomers and loss of active species.

A variety of supported bimetallic catalysts were prepared through immobilization of AlCl3 and TiCl4 on different porous materials and used for the oligomerization of 1-decene in a fixed-bed reactor. The supported catalysts were characterized by various techniques including X-ray photoelectron spectroscopy (XPS), 27Al MAS NMR, N2 adsorption, adsorbed pyridine infrared (Py-IR), thermogravimetry and differential scanning calorimetry (TG–DSC), energy-dispersive spectrometry (EDS), and content measurement of active species. Their catalytic activity was examined and the underlying deactivation mechanism was explored. The initial catalytic activity was observed to be a linear function of the chlorine content of the supported catalyst. A catalyst using a coal-derived activated carbon support has the highest loading and exhibits the highest yield of polyalphaolefin (PAO), while a γ-Al2O3-supported catalyst gives higher stability. In addition, thermal treatment of the γ-Al2O3-supported catalyst results in reduced initial activity but enhanced stability. Both the loss of active species and the blockage and coverage of the pore structure by oligomers account for the deactivation of the supported catalyst.

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