Intrinsic effect of crystalline phases in TiO2 on the Fischer-Tropsch synthesis over well-defined and uniform pore-structure Fe/TiO2/SiO2 catalysts

摘要

A series of well-defined and uniform pore-structure (WDUPS) TiO2/SiO2 supports with various percentages of rutile TiO2 was developed. Then Fe was introduced into the as-prepared WDUPS supports by incipient wetness impregnation to obtain WDUPS Fe/TiO2/SiO2 catalysts for the Fischer-Tropsch (FT) synthesis. Due to a similar surface OH density in the supports and the same pore structure and Fe loading, the catalytic performance of WDUPS catalysts dominated by percentages of rutile TiO2. Based on the catalytic performance for FT synthesis and the characterization of the H-2 temperature-programmed reduction (H-2-TPR) and the X-ray photoelectron spectroscopy (XPS), the results suggested that rutile TiO2 acted as a structure promoter in titania-supported iron catalysts and led to an increase in the catalytic activity during FT synthesis. The C5+ selectivity had an increase as the percentage of the rutile phase increased, which was also probably because of rutile TiO2 as a structure promoter for enhancing chain growth.